1 /* 2 * QEMU System Emulator block driver 3 * 4 * Copyright (c) 2003 Fabrice Bellard 5 * Copyright (c) 2020 Virtuozzo International GmbH. 6 * 7 * Permission is hereby granted, free of charge, to any person obtaining a copy 8 * of this software and associated documentation files (the "Software"), to deal 9 * in the Software without restriction, including without limitation the rights 10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 11 * copies of the Software, and to permit persons to whom the Software is 12 * furnished to do so, subject to the following conditions: 13 * 14 * The above copyright notice and this permission notice shall be included in 15 * all copies or substantial portions of the Software. 16 * 17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 23 * THE SOFTWARE. 24 */ 25 26 #include "qemu/osdep.h" 27 #include "block/trace.h" 28 #include "block/block_int.h" 29 #include "block/blockjob.h" 30 #include "block/dirty-bitmap.h" 31 #include "block/fuse.h" 32 #include "block/nbd.h" 33 #include "block/qdict.h" 34 #include "qemu/error-report.h" 35 #include "block/module_block.h" 36 #include "qemu/main-loop.h" 37 #include "qemu/module.h" 38 #include "qapi/error.h" 39 #include "qapi/qmp/qdict.h" 40 #include "qapi/qmp/qjson.h" 41 #include "qapi/qmp/qnull.h" 42 #include "qapi/qmp/qstring.h" 43 #include "qapi/qobject-output-visitor.h" 44 #include "qapi/qapi-visit-block-core.h" 45 #include "sysemu/block-backend.h" 46 #include "qemu/notify.h" 47 #include "qemu/option.h" 48 #include "qemu/coroutine.h" 49 #include "block/qapi.h" 50 #include "qemu/timer.h" 51 #include "qemu/cutils.h" 52 #include "qemu/id.h" 53 #include "qemu/range.h" 54 #include "qemu/rcu.h" 55 #include "block/coroutines.h" 56 57 #ifdef CONFIG_BSD 58 #include <sys/ioctl.h> 59 #include <sys/queue.h> 60 #if defined(HAVE_SYS_DISK_H) 61 #include <sys/disk.h> 62 #endif 63 #endif 64 65 #ifdef _WIN32 66 #include <windows.h> 67 #endif 68 69 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */ 70 71 /* Protected by BQL */ 72 static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states = 73 QTAILQ_HEAD_INITIALIZER(graph_bdrv_states); 74 75 /* Protected by BQL */ 76 static QTAILQ_HEAD(, BlockDriverState) all_bdrv_states = 77 QTAILQ_HEAD_INITIALIZER(all_bdrv_states); 78 79 /* Protected by BQL */ 80 static QLIST_HEAD(, BlockDriver) bdrv_drivers = 81 QLIST_HEAD_INITIALIZER(bdrv_drivers); 82 83 static BlockDriverState *bdrv_open_inherit(const char *filename, 84 const char *reference, 85 QDict *options, int flags, 86 BlockDriverState *parent, 87 const BdrvChildClass *child_class, 88 BdrvChildRole child_role, 89 Error **errp); 90 91 static bool bdrv_recurse_has_child(BlockDriverState *bs, 92 BlockDriverState *child); 93 94 static void GRAPH_WRLOCK 95 bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs); 96 97 static void GRAPH_WRLOCK 98 bdrv_remove_child(BdrvChild *child, Transaction *tran); 99 100 static int bdrv_reopen_prepare(BDRVReopenState *reopen_state, 101 BlockReopenQueue *queue, 102 Transaction *change_child_tran, Error **errp); 103 static void bdrv_reopen_commit(BDRVReopenState *reopen_state); 104 static void bdrv_reopen_abort(BDRVReopenState *reopen_state); 105 106 static bool bdrv_backing_overridden(BlockDriverState *bs); 107 108 static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx, 109 GHashTable *visited, Transaction *tran, 110 Error **errp); 111 112 /* If non-zero, use only whitelisted block drivers */ 113 static int use_bdrv_whitelist; 114 115 #ifdef _WIN32 116 static int is_windows_drive_prefix(const char *filename) 117 { 118 return (((filename[0] >= 'a' && filename[0] <= 'z') || 119 (filename[0] >= 'A' && filename[0] <= 'Z')) && 120 filename[1] == ':'); 121 } 122 123 int is_windows_drive(const char *filename) 124 { 125 if (is_windows_drive_prefix(filename) && 126 filename[2] == '\0') 127 return 1; 128 if (strstart(filename, "\\\\.\\", NULL) || 129 strstart(filename, "//./", NULL)) 130 return 1; 131 return 0; 132 } 133 #endif 134 135 size_t bdrv_opt_mem_align(BlockDriverState *bs) 136 { 137 if (!bs || !bs->drv) { 138 /* page size or 4k (hdd sector size) should be on the safe side */ 139 return MAX(4096, qemu_real_host_page_size()); 140 } 141 IO_CODE(); 142 143 return bs->bl.opt_mem_alignment; 144 } 145 146 size_t bdrv_min_mem_align(BlockDriverState *bs) 147 { 148 if (!bs || !bs->drv) { 149 /* page size or 4k (hdd sector size) should be on the safe side */ 150 return MAX(4096, qemu_real_host_page_size()); 151 } 152 IO_CODE(); 153 154 return bs->bl.min_mem_alignment; 155 } 156 157 /* check if the path starts with "<protocol>:" */ 158 int path_has_protocol(const char *path) 159 { 160 const char *p; 161 162 #ifdef _WIN32 163 if (is_windows_drive(path) || 164 is_windows_drive_prefix(path)) { 165 return 0; 166 } 167 p = path + strcspn(path, ":/\\"); 168 #else 169 p = path + strcspn(path, ":/"); 170 #endif 171 172 return *p == ':'; 173 } 174 175 int path_is_absolute(const char *path) 176 { 177 #ifdef _WIN32 178 /* specific case for names like: "\\.\d:" */ 179 if (is_windows_drive(path) || is_windows_drive_prefix(path)) { 180 return 1; 181 } 182 return (*path == '/' || *path == '\\'); 183 #else 184 return (*path == '/'); 185 #endif 186 } 187 188 /* if filename is absolute, just return its duplicate. Otherwise, build a 189 path to it by considering it is relative to base_path. URL are 190 supported. */ 191 char *path_combine(const char *base_path, const char *filename) 192 { 193 const char *protocol_stripped = NULL; 194 const char *p, *p1; 195 char *result; 196 int len; 197 198 if (path_is_absolute(filename)) { 199 return g_strdup(filename); 200 } 201 202 if (path_has_protocol(base_path)) { 203 protocol_stripped = strchr(base_path, ':'); 204 if (protocol_stripped) { 205 protocol_stripped++; 206 } 207 } 208 p = protocol_stripped ?: base_path; 209 210 p1 = strrchr(base_path, '/'); 211 #ifdef _WIN32 212 { 213 const char *p2; 214 p2 = strrchr(base_path, '\\'); 215 if (!p1 || p2 > p1) { 216 p1 = p2; 217 } 218 } 219 #endif 220 if (p1) { 221 p1++; 222 } else { 223 p1 = base_path; 224 } 225 if (p1 > p) { 226 p = p1; 227 } 228 len = p - base_path; 229 230 result = g_malloc(len + strlen(filename) + 1); 231 memcpy(result, base_path, len); 232 strcpy(result + len, filename); 233 234 return result; 235 } 236 237 /* 238 * Helper function for bdrv_parse_filename() implementations to remove optional 239 * protocol prefixes (especially "file:") from a filename and for putting the 240 * stripped filename into the options QDict if there is such a prefix. 241 */ 242 void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix, 243 QDict *options) 244 { 245 if (strstart(filename, prefix, &filename)) { 246 /* Stripping the explicit protocol prefix may result in a protocol 247 * prefix being (wrongly) detected (if the filename contains a colon) */ 248 if (path_has_protocol(filename)) { 249 GString *fat_filename; 250 251 /* This means there is some colon before the first slash; therefore, 252 * this cannot be an absolute path */ 253 assert(!path_is_absolute(filename)); 254 255 /* And we can thus fix the protocol detection issue by prefixing it 256 * by "./" */ 257 fat_filename = g_string_new("./"); 258 g_string_append(fat_filename, filename); 259 260 assert(!path_has_protocol(fat_filename->str)); 261 262 qdict_put(options, "filename", 263 qstring_from_gstring(fat_filename)); 264 } else { 265 /* If no protocol prefix was detected, we can use the shortened 266 * filename as-is */ 267 qdict_put_str(options, "filename", filename); 268 } 269 } 270 } 271 272 273 /* Returns whether the image file is opened as read-only. Note that this can 274 * return false and writing to the image file is still not possible because the 275 * image is inactivated. */ 276 bool bdrv_is_read_only(BlockDriverState *bs) 277 { 278 IO_CODE(); 279 return !(bs->open_flags & BDRV_O_RDWR); 280 } 281 282 static int GRAPH_RDLOCK 283 bdrv_can_set_read_only(BlockDriverState *bs, bool read_only, 284 bool ignore_allow_rdw, Error **errp) 285 { 286 IO_CODE(); 287 288 /* Do not set read_only if copy_on_read is enabled */ 289 if (bs->copy_on_read && read_only) { 290 error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled", 291 bdrv_get_device_or_node_name(bs)); 292 return -EINVAL; 293 } 294 295 /* Do not clear read_only if it is prohibited */ 296 if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) && 297 !ignore_allow_rdw) 298 { 299 error_setg(errp, "Node '%s' is read only", 300 bdrv_get_device_or_node_name(bs)); 301 return -EPERM; 302 } 303 304 return 0; 305 } 306 307 /* 308 * Called by a driver that can only provide a read-only image. 309 * 310 * Returns 0 if the node is already read-only or it could switch the node to 311 * read-only because BDRV_O_AUTO_RDONLY is set. 312 * 313 * Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set 314 * or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg 315 * is not NULL, it is used as the error message for the Error object. 316 */ 317 int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg, 318 Error **errp) 319 { 320 int ret = 0; 321 IO_CODE(); 322 323 if (!(bs->open_flags & BDRV_O_RDWR)) { 324 return 0; 325 } 326 if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) { 327 goto fail; 328 } 329 330 ret = bdrv_can_set_read_only(bs, true, false, NULL); 331 if (ret < 0) { 332 goto fail; 333 } 334 335 bs->open_flags &= ~BDRV_O_RDWR; 336 337 return 0; 338 339 fail: 340 error_setg(errp, "%s", errmsg ?: "Image is read-only"); 341 return -EACCES; 342 } 343 344 /* 345 * If @backing is empty, this function returns NULL without setting 346 * @errp. In all other cases, NULL will only be returned with @errp 347 * set. 348 * 349 * Therefore, a return value of NULL without @errp set means that 350 * there is no backing file; if @errp is set, there is one but its 351 * absolute filename cannot be generated. 352 */ 353 char *bdrv_get_full_backing_filename_from_filename(const char *backed, 354 const char *backing, 355 Error **errp) 356 { 357 if (backing[0] == '\0') { 358 return NULL; 359 } else if (path_has_protocol(backing) || path_is_absolute(backing)) { 360 return g_strdup(backing); 361 } else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) { 362 error_setg(errp, "Cannot use relative backing file names for '%s'", 363 backed); 364 return NULL; 365 } else { 366 return path_combine(backed, backing); 367 } 368 } 369 370 /* 371 * If @filename is empty or NULL, this function returns NULL without 372 * setting @errp. In all other cases, NULL will only be returned with 373 * @errp set. 374 */ 375 static char * GRAPH_RDLOCK 376 bdrv_make_absolute_filename(BlockDriverState *relative_to, 377 const char *filename, Error **errp) 378 { 379 char *dir, *full_name; 380 381 if (!filename || filename[0] == '\0') { 382 return NULL; 383 } else if (path_has_protocol(filename) || path_is_absolute(filename)) { 384 return g_strdup(filename); 385 } 386 387 dir = bdrv_dirname(relative_to, errp); 388 if (!dir) { 389 return NULL; 390 } 391 392 full_name = g_strconcat(dir, filename, NULL); 393 g_free(dir); 394 return full_name; 395 } 396 397 char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp) 398 { 399 GLOBAL_STATE_CODE(); 400 return bdrv_make_absolute_filename(bs, bs->backing_file, errp); 401 } 402 403 void bdrv_register(BlockDriver *bdrv) 404 { 405 assert(bdrv->format_name); 406 GLOBAL_STATE_CODE(); 407 QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list); 408 } 409 410 BlockDriverState *bdrv_new(void) 411 { 412 BlockDriverState *bs; 413 int i; 414 415 GLOBAL_STATE_CODE(); 416 417 bs = g_new0(BlockDriverState, 1); 418 QLIST_INIT(&bs->dirty_bitmaps); 419 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 420 QLIST_INIT(&bs->op_blockers[i]); 421 } 422 qemu_mutex_init(&bs->reqs_lock); 423 qemu_mutex_init(&bs->dirty_bitmap_mutex); 424 bs->refcnt = 1; 425 bs->aio_context = qemu_get_aio_context(); 426 427 qemu_co_queue_init(&bs->flush_queue); 428 429 qemu_co_mutex_init(&bs->bsc_modify_lock); 430 bs->block_status_cache = g_new0(BdrvBlockStatusCache, 1); 431 432 for (i = 0; i < bdrv_drain_all_count; i++) { 433 bdrv_drained_begin(bs); 434 } 435 436 QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list); 437 438 return bs; 439 } 440 441 static BlockDriver *bdrv_do_find_format(const char *format_name) 442 { 443 BlockDriver *drv1; 444 GLOBAL_STATE_CODE(); 445 446 QLIST_FOREACH(drv1, &bdrv_drivers, list) { 447 if (!strcmp(drv1->format_name, format_name)) { 448 return drv1; 449 } 450 } 451 452 return NULL; 453 } 454 455 BlockDriver *bdrv_find_format(const char *format_name) 456 { 457 BlockDriver *drv1; 458 int i; 459 460 GLOBAL_STATE_CODE(); 461 462 drv1 = bdrv_do_find_format(format_name); 463 if (drv1) { 464 return drv1; 465 } 466 467 /* The driver isn't registered, maybe we need to load a module */ 468 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) { 469 if (!strcmp(block_driver_modules[i].format_name, format_name)) { 470 Error *local_err = NULL; 471 int rv = block_module_load(block_driver_modules[i].library_name, 472 &local_err); 473 if (rv > 0) { 474 return bdrv_do_find_format(format_name); 475 } else if (rv < 0) { 476 error_report_err(local_err); 477 } 478 break; 479 } 480 } 481 return NULL; 482 } 483 484 static int bdrv_format_is_whitelisted(const char *format_name, bool read_only) 485 { 486 static const char *whitelist_rw[] = { 487 CONFIG_BDRV_RW_WHITELIST 488 NULL 489 }; 490 static const char *whitelist_ro[] = { 491 CONFIG_BDRV_RO_WHITELIST 492 NULL 493 }; 494 const char **p; 495 496 if (!whitelist_rw[0] && !whitelist_ro[0]) { 497 return 1; /* no whitelist, anything goes */ 498 } 499 500 for (p = whitelist_rw; *p; p++) { 501 if (!strcmp(format_name, *p)) { 502 return 1; 503 } 504 } 505 if (read_only) { 506 for (p = whitelist_ro; *p; p++) { 507 if (!strcmp(format_name, *p)) { 508 return 1; 509 } 510 } 511 } 512 return 0; 513 } 514 515 int bdrv_is_whitelisted(BlockDriver *drv, bool read_only) 516 { 517 GLOBAL_STATE_CODE(); 518 return bdrv_format_is_whitelisted(drv->format_name, read_only); 519 } 520 521 bool bdrv_uses_whitelist(void) 522 { 523 return use_bdrv_whitelist; 524 } 525 526 typedef struct CreateCo { 527 BlockDriver *drv; 528 char *filename; 529 QemuOpts *opts; 530 int ret; 531 Error *err; 532 } CreateCo; 533 534 int coroutine_fn bdrv_co_create(BlockDriver *drv, const char *filename, 535 QemuOpts *opts, Error **errp) 536 { 537 int ret; 538 GLOBAL_STATE_CODE(); 539 ERRP_GUARD(); 540 541 if (!drv->bdrv_co_create_opts) { 542 error_setg(errp, "Driver '%s' does not support image creation", 543 drv->format_name); 544 return -ENOTSUP; 545 } 546 547 ret = drv->bdrv_co_create_opts(drv, filename, opts, errp); 548 if (ret < 0 && !*errp) { 549 error_setg_errno(errp, -ret, "Could not create image"); 550 } 551 552 return ret; 553 } 554 555 /** 556 * Helper function for bdrv_create_file_fallback(): Resize @blk to at 557 * least the given @minimum_size. 558 * 559 * On success, return @blk's actual length. 560 * Otherwise, return -errno. 561 */ 562 static int64_t coroutine_fn GRAPH_UNLOCKED 563 create_file_fallback_truncate(BlockBackend *blk, int64_t minimum_size, 564 Error **errp) 565 { 566 Error *local_err = NULL; 567 int64_t size; 568 int ret; 569 570 GLOBAL_STATE_CODE(); 571 572 ret = blk_co_truncate(blk, minimum_size, false, PREALLOC_MODE_OFF, 0, 573 &local_err); 574 if (ret < 0 && ret != -ENOTSUP) { 575 error_propagate(errp, local_err); 576 return ret; 577 } 578 579 size = blk_co_getlength(blk); 580 if (size < 0) { 581 error_free(local_err); 582 error_setg_errno(errp, -size, 583 "Failed to inquire the new image file's length"); 584 return size; 585 } 586 587 if (size < minimum_size) { 588 /* Need to grow the image, but we failed to do that */ 589 error_propagate(errp, local_err); 590 return -ENOTSUP; 591 } 592 593 error_free(local_err); 594 local_err = NULL; 595 596 return size; 597 } 598 599 /** 600 * Helper function for bdrv_create_file_fallback(): Zero the first 601 * sector to remove any potentially pre-existing image header. 602 */ 603 static int coroutine_fn 604 create_file_fallback_zero_first_sector(BlockBackend *blk, 605 int64_t current_size, 606 Error **errp) 607 { 608 int64_t bytes_to_clear; 609 int ret; 610 611 GLOBAL_STATE_CODE(); 612 613 bytes_to_clear = MIN(current_size, BDRV_SECTOR_SIZE); 614 if (bytes_to_clear) { 615 ret = blk_co_pwrite_zeroes(blk, 0, bytes_to_clear, BDRV_REQ_MAY_UNMAP); 616 if (ret < 0) { 617 error_setg_errno(errp, -ret, 618 "Failed to clear the new image's first sector"); 619 return ret; 620 } 621 } 622 623 return 0; 624 } 625 626 /** 627 * Simple implementation of bdrv_co_create_opts for protocol drivers 628 * which only support creation via opening a file 629 * (usually existing raw storage device) 630 */ 631 int coroutine_fn bdrv_co_create_opts_simple(BlockDriver *drv, 632 const char *filename, 633 QemuOpts *opts, 634 Error **errp) 635 { 636 BlockBackend *blk; 637 QDict *options; 638 int64_t size = 0; 639 char *buf = NULL; 640 PreallocMode prealloc; 641 Error *local_err = NULL; 642 int ret; 643 644 GLOBAL_STATE_CODE(); 645 646 size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0); 647 buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC); 648 prealloc = qapi_enum_parse(&PreallocMode_lookup, buf, 649 PREALLOC_MODE_OFF, &local_err); 650 g_free(buf); 651 if (local_err) { 652 error_propagate(errp, local_err); 653 return -EINVAL; 654 } 655 656 if (prealloc != PREALLOC_MODE_OFF) { 657 error_setg(errp, "Unsupported preallocation mode '%s'", 658 PreallocMode_str(prealloc)); 659 return -ENOTSUP; 660 } 661 662 options = qdict_new(); 663 qdict_put_str(options, "driver", drv->format_name); 664 665 blk = blk_co_new_open(filename, NULL, options, 666 BDRV_O_RDWR | BDRV_O_RESIZE, errp); 667 if (!blk) { 668 error_prepend(errp, "Protocol driver '%s' does not support creating " 669 "new images, so an existing image must be selected as " 670 "the target; however, opening the given target as an " 671 "existing image failed: ", 672 drv->format_name); 673 return -EINVAL; 674 } 675 676 size = create_file_fallback_truncate(blk, size, errp); 677 if (size < 0) { 678 ret = size; 679 goto out; 680 } 681 682 ret = create_file_fallback_zero_first_sector(blk, size, errp); 683 if (ret < 0) { 684 goto out; 685 } 686 687 ret = 0; 688 out: 689 blk_co_unref(blk); 690 return ret; 691 } 692 693 int coroutine_fn bdrv_co_create_file(const char *filename, QemuOpts *opts, 694 Error **errp) 695 { 696 QemuOpts *protocol_opts; 697 BlockDriver *drv; 698 QDict *qdict; 699 int ret; 700 701 GLOBAL_STATE_CODE(); 702 703 drv = bdrv_find_protocol(filename, true, errp); 704 if (drv == NULL) { 705 return -ENOENT; 706 } 707 708 if (!drv->create_opts) { 709 error_setg(errp, "Driver '%s' does not support image creation", 710 drv->format_name); 711 return -ENOTSUP; 712 } 713 714 /* 715 * 'opts' contains a QemuOptsList with a combination of format and protocol 716 * default values. 717 * 718 * The format properly removes its options, but the default values remain 719 * in 'opts->list'. So if the protocol has options with the same name 720 * (e.g. rbd has 'cluster_size' as qcow2), it will see the default values 721 * of the format, since for overlapping options, the format wins. 722 * 723 * To avoid this issue, lets convert QemuOpts to QDict, in this way we take 724 * only the set options, and then convert it back to QemuOpts, using the 725 * create_opts of the protocol. So the new QemuOpts, will contain only the 726 * protocol defaults. 727 */ 728 qdict = qemu_opts_to_qdict(opts, NULL); 729 protocol_opts = qemu_opts_from_qdict(drv->create_opts, qdict, errp); 730 if (protocol_opts == NULL) { 731 ret = -EINVAL; 732 goto out; 733 } 734 735 ret = bdrv_co_create(drv, filename, protocol_opts, errp); 736 out: 737 qemu_opts_del(protocol_opts); 738 qobject_unref(qdict); 739 return ret; 740 } 741 742 int coroutine_fn bdrv_co_delete_file(BlockDriverState *bs, Error **errp) 743 { 744 Error *local_err = NULL; 745 int ret; 746 747 IO_CODE(); 748 assert(bs != NULL); 749 assert_bdrv_graph_readable(); 750 751 if (!bs->drv) { 752 error_setg(errp, "Block node '%s' is not opened", bs->filename); 753 return -ENOMEDIUM; 754 } 755 756 if (!bs->drv->bdrv_co_delete_file) { 757 error_setg(errp, "Driver '%s' does not support image deletion", 758 bs->drv->format_name); 759 return -ENOTSUP; 760 } 761 762 ret = bs->drv->bdrv_co_delete_file(bs, &local_err); 763 if (ret < 0) { 764 error_propagate(errp, local_err); 765 } 766 767 return ret; 768 } 769 770 void coroutine_fn bdrv_co_delete_file_noerr(BlockDriverState *bs) 771 { 772 Error *local_err = NULL; 773 int ret; 774 IO_CODE(); 775 776 if (!bs) { 777 return; 778 } 779 780 ret = bdrv_co_delete_file(bs, &local_err); 781 /* 782 * ENOTSUP will happen if the block driver doesn't support 783 * the 'bdrv_co_delete_file' interface. This is a predictable 784 * scenario and shouldn't be reported back to the user. 785 */ 786 if (ret == -ENOTSUP) { 787 error_free(local_err); 788 } else if (ret < 0) { 789 error_report_err(local_err); 790 } 791 } 792 793 /** 794 * Try to get @bs's logical and physical block size. 795 * On success, store them in @bsz struct and return 0. 796 * On failure return -errno. 797 * @bs must not be empty. 798 */ 799 int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz) 800 { 801 BlockDriver *drv = bs->drv; 802 BlockDriverState *filtered = bdrv_filter_bs(bs); 803 GLOBAL_STATE_CODE(); 804 805 if (drv && drv->bdrv_probe_blocksizes) { 806 return drv->bdrv_probe_blocksizes(bs, bsz); 807 } else if (filtered) { 808 return bdrv_probe_blocksizes(filtered, bsz); 809 } 810 811 return -ENOTSUP; 812 } 813 814 /** 815 * Try to get @bs's geometry (cyls, heads, sectors). 816 * On success, store them in @geo struct and return 0. 817 * On failure return -errno. 818 * @bs must not be empty. 819 */ 820 int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo) 821 { 822 BlockDriver *drv = bs->drv; 823 BlockDriverState *filtered; 824 825 GLOBAL_STATE_CODE(); 826 GRAPH_RDLOCK_GUARD_MAINLOOP(); 827 828 if (drv && drv->bdrv_probe_geometry) { 829 return drv->bdrv_probe_geometry(bs, geo); 830 } 831 832 filtered = bdrv_filter_bs(bs); 833 if (filtered) { 834 return bdrv_probe_geometry(filtered, geo); 835 } 836 837 return -ENOTSUP; 838 } 839 840 /* 841 * Create a uniquely-named empty temporary file. 842 * Return the actual file name used upon success, otherwise NULL. 843 * This string should be freed with g_free() when not needed any longer. 844 * 845 * Note: creating a temporary file for the caller to (re)open is 846 * inherently racy. Use g_file_open_tmp() instead whenever practical. 847 */ 848 char *create_tmp_file(Error **errp) 849 { 850 int fd; 851 const char *tmpdir; 852 g_autofree char *filename = NULL; 853 854 tmpdir = g_get_tmp_dir(); 855 #ifndef _WIN32 856 /* 857 * See commit 69bef79 ("block: use /var/tmp instead of /tmp for -snapshot") 858 * 859 * This function is used to create temporary disk images (like -snapshot), 860 * so the files can become very large. /tmp is often a tmpfs where as 861 * /var/tmp is usually on a disk, so more appropriate for disk images. 862 */ 863 if (!g_strcmp0(tmpdir, "/tmp")) { 864 tmpdir = "/var/tmp"; 865 } 866 #endif 867 868 filename = g_strdup_printf("%s/vl.XXXXXX", tmpdir); 869 fd = g_mkstemp(filename); 870 if (fd < 0) { 871 error_setg_errno(errp, errno, "Could not open temporary file '%s'", 872 filename); 873 return NULL; 874 } 875 close(fd); 876 877 return g_steal_pointer(&filename); 878 } 879 880 /* 881 * Detect host devices. By convention, /dev/cdrom[N] is always 882 * recognized as a host CDROM. 883 */ 884 static BlockDriver *find_hdev_driver(const char *filename) 885 { 886 int score_max = 0, score; 887 BlockDriver *drv = NULL, *d; 888 GLOBAL_STATE_CODE(); 889 890 QLIST_FOREACH(d, &bdrv_drivers, list) { 891 if (d->bdrv_probe_device) { 892 score = d->bdrv_probe_device(filename); 893 if (score > score_max) { 894 score_max = score; 895 drv = d; 896 } 897 } 898 } 899 900 return drv; 901 } 902 903 static BlockDriver *bdrv_do_find_protocol(const char *protocol) 904 { 905 BlockDriver *drv1; 906 GLOBAL_STATE_CODE(); 907 908 QLIST_FOREACH(drv1, &bdrv_drivers, list) { 909 if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) { 910 return drv1; 911 } 912 } 913 914 return NULL; 915 } 916 917 BlockDriver *bdrv_find_protocol(const char *filename, 918 bool allow_protocol_prefix, 919 Error **errp) 920 { 921 BlockDriver *drv1; 922 char protocol[128]; 923 int len; 924 const char *p; 925 int i; 926 927 GLOBAL_STATE_CODE(); 928 /* TODO Drivers without bdrv_file_open must be specified explicitly */ 929 930 /* 931 * XXX(hch): we really should not let host device detection 932 * override an explicit protocol specification, but moving this 933 * later breaks access to device names with colons in them. 934 * Thanks to the brain-dead persistent naming schemes on udev- 935 * based Linux systems those actually are quite common. 936 */ 937 drv1 = find_hdev_driver(filename); 938 if (drv1) { 939 return drv1; 940 } 941 942 if (!path_has_protocol(filename) || !allow_protocol_prefix) { 943 return &bdrv_file; 944 } 945 946 p = strchr(filename, ':'); 947 assert(p != NULL); 948 len = p - filename; 949 if (len > sizeof(protocol) - 1) 950 len = sizeof(protocol) - 1; 951 memcpy(protocol, filename, len); 952 protocol[len] = '\0'; 953 954 drv1 = bdrv_do_find_protocol(protocol); 955 if (drv1) { 956 return drv1; 957 } 958 959 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) { 960 if (block_driver_modules[i].protocol_name && 961 !strcmp(block_driver_modules[i].protocol_name, protocol)) { 962 int rv = block_module_load(block_driver_modules[i].library_name, errp); 963 if (rv > 0) { 964 drv1 = bdrv_do_find_protocol(protocol); 965 } else if (rv < 0) { 966 return NULL; 967 } 968 break; 969 } 970 } 971 972 if (!drv1) { 973 error_setg(errp, "Unknown protocol '%s'", protocol); 974 } 975 return drv1; 976 } 977 978 /* 979 * Guess image format by probing its contents. 980 * This is not a good idea when your image is raw (CVE-2008-2004), but 981 * we do it anyway for backward compatibility. 982 * 983 * @buf contains the image's first @buf_size bytes. 984 * @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE, 985 * but can be smaller if the image file is smaller) 986 * @filename is its filename. 987 * 988 * For all block drivers, call the bdrv_probe() method to get its 989 * probing score. 990 * Return the first block driver with the highest probing score. 991 */ 992 BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size, 993 const char *filename) 994 { 995 int score_max = 0, score; 996 BlockDriver *drv = NULL, *d; 997 IO_CODE(); 998 999 QLIST_FOREACH(d, &bdrv_drivers, list) { 1000 if (d->bdrv_probe) { 1001 score = d->bdrv_probe(buf, buf_size, filename); 1002 if (score > score_max) { 1003 score_max = score; 1004 drv = d; 1005 } 1006 } 1007 } 1008 1009 return drv; 1010 } 1011 1012 static int find_image_format(BlockBackend *file, const char *filename, 1013 BlockDriver **pdrv, Error **errp) 1014 { 1015 BlockDriver *drv; 1016 uint8_t buf[BLOCK_PROBE_BUF_SIZE]; 1017 int ret = 0; 1018 1019 GLOBAL_STATE_CODE(); 1020 1021 /* Return the raw BlockDriver * to scsi-generic devices or empty drives */ 1022 if (blk_is_sg(file) || !blk_is_inserted(file) || blk_getlength(file) == 0) { 1023 *pdrv = &bdrv_raw; 1024 return ret; 1025 } 1026 1027 ret = blk_pread(file, 0, sizeof(buf), buf, 0); 1028 if (ret < 0) { 1029 error_setg_errno(errp, -ret, "Could not read image for determining its " 1030 "format"); 1031 *pdrv = NULL; 1032 return ret; 1033 } 1034 1035 drv = bdrv_probe_all(buf, sizeof(buf), filename); 1036 if (!drv) { 1037 error_setg(errp, "Could not determine image format: No compatible " 1038 "driver found"); 1039 *pdrv = NULL; 1040 return -ENOENT; 1041 } 1042 1043 *pdrv = drv; 1044 return 0; 1045 } 1046 1047 /** 1048 * Set the current 'total_sectors' value 1049 * Return 0 on success, -errno on error. 1050 */ 1051 int coroutine_fn bdrv_co_refresh_total_sectors(BlockDriverState *bs, 1052 int64_t hint) 1053 { 1054 BlockDriver *drv = bs->drv; 1055 IO_CODE(); 1056 assert_bdrv_graph_readable(); 1057 1058 if (!drv) { 1059 return -ENOMEDIUM; 1060 } 1061 1062 /* Do not attempt drv->bdrv_co_getlength() on scsi-generic devices */ 1063 if (bdrv_is_sg(bs)) 1064 return 0; 1065 1066 /* query actual device if possible, otherwise just trust the hint */ 1067 if (drv->bdrv_co_getlength) { 1068 int64_t length = drv->bdrv_co_getlength(bs); 1069 if (length < 0) { 1070 return length; 1071 } 1072 hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE); 1073 } 1074 1075 bs->total_sectors = hint; 1076 1077 if (bs->total_sectors * BDRV_SECTOR_SIZE > BDRV_MAX_LENGTH) { 1078 return -EFBIG; 1079 } 1080 1081 return 0; 1082 } 1083 1084 /** 1085 * Combines a QDict of new block driver @options with any missing options taken 1086 * from @old_options, so that leaving out an option defaults to its old value. 1087 */ 1088 static void bdrv_join_options(BlockDriverState *bs, QDict *options, 1089 QDict *old_options) 1090 { 1091 GLOBAL_STATE_CODE(); 1092 if (bs->drv && bs->drv->bdrv_join_options) { 1093 bs->drv->bdrv_join_options(options, old_options); 1094 } else { 1095 qdict_join(options, old_options, false); 1096 } 1097 } 1098 1099 static BlockdevDetectZeroesOptions bdrv_parse_detect_zeroes(QemuOpts *opts, 1100 int open_flags, 1101 Error **errp) 1102 { 1103 Error *local_err = NULL; 1104 char *value = qemu_opt_get_del(opts, "detect-zeroes"); 1105 BlockdevDetectZeroesOptions detect_zeroes = 1106 qapi_enum_parse(&BlockdevDetectZeroesOptions_lookup, value, 1107 BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF, &local_err); 1108 GLOBAL_STATE_CODE(); 1109 g_free(value); 1110 if (local_err) { 1111 error_propagate(errp, local_err); 1112 return detect_zeroes; 1113 } 1114 1115 if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP && 1116 !(open_flags & BDRV_O_UNMAP)) 1117 { 1118 error_setg(errp, "setting detect-zeroes to unmap is not allowed " 1119 "without setting discard operation to unmap"); 1120 } 1121 1122 return detect_zeroes; 1123 } 1124 1125 /** 1126 * Set open flags for aio engine 1127 * 1128 * Return 0 on success, -1 if the engine specified is invalid 1129 */ 1130 int bdrv_parse_aio(const char *mode, int *flags) 1131 { 1132 if (!strcmp(mode, "threads")) { 1133 /* do nothing, default */ 1134 } else if (!strcmp(mode, "native")) { 1135 *flags |= BDRV_O_NATIVE_AIO; 1136 #ifdef CONFIG_LINUX_IO_URING 1137 } else if (!strcmp(mode, "io_uring")) { 1138 *flags |= BDRV_O_IO_URING; 1139 #endif 1140 } else { 1141 return -1; 1142 } 1143 1144 return 0; 1145 } 1146 1147 /** 1148 * Set open flags for a given discard mode 1149 * 1150 * Return 0 on success, -1 if the discard mode was invalid. 1151 */ 1152 int bdrv_parse_discard_flags(const char *mode, int *flags) 1153 { 1154 *flags &= ~BDRV_O_UNMAP; 1155 1156 if (!strcmp(mode, "off") || !strcmp(mode, "ignore")) { 1157 /* do nothing */ 1158 } else if (!strcmp(mode, "on") || !strcmp(mode, "unmap")) { 1159 *flags |= BDRV_O_UNMAP; 1160 } else { 1161 return -1; 1162 } 1163 1164 return 0; 1165 } 1166 1167 /** 1168 * Set open flags for a given cache mode 1169 * 1170 * Return 0 on success, -1 if the cache mode was invalid. 1171 */ 1172 int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough) 1173 { 1174 *flags &= ~BDRV_O_CACHE_MASK; 1175 1176 if (!strcmp(mode, "off") || !strcmp(mode, "none")) { 1177 *writethrough = false; 1178 *flags |= BDRV_O_NOCACHE; 1179 } else if (!strcmp(mode, "directsync")) { 1180 *writethrough = true; 1181 *flags |= BDRV_O_NOCACHE; 1182 } else if (!strcmp(mode, "writeback")) { 1183 *writethrough = false; 1184 } else if (!strcmp(mode, "unsafe")) { 1185 *writethrough = false; 1186 *flags |= BDRV_O_NO_FLUSH; 1187 } else if (!strcmp(mode, "writethrough")) { 1188 *writethrough = true; 1189 } else { 1190 return -1; 1191 } 1192 1193 return 0; 1194 } 1195 1196 static char *bdrv_child_get_parent_desc(BdrvChild *c) 1197 { 1198 BlockDriverState *parent = c->opaque; 1199 return g_strdup_printf("node '%s'", bdrv_get_node_name(parent)); 1200 } 1201 1202 static void GRAPH_RDLOCK bdrv_child_cb_drained_begin(BdrvChild *child) 1203 { 1204 BlockDriverState *bs = child->opaque; 1205 bdrv_do_drained_begin_quiesce(bs, NULL); 1206 } 1207 1208 static bool GRAPH_RDLOCK bdrv_child_cb_drained_poll(BdrvChild *child) 1209 { 1210 BlockDriverState *bs = child->opaque; 1211 return bdrv_drain_poll(bs, NULL, false); 1212 } 1213 1214 static void GRAPH_RDLOCK bdrv_child_cb_drained_end(BdrvChild *child) 1215 { 1216 BlockDriverState *bs = child->opaque; 1217 bdrv_drained_end(bs); 1218 } 1219 1220 static int bdrv_child_cb_inactivate(BdrvChild *child) 1221 { 1222 BlockDriverState *bs = child->opaque; 1223 GLOBAL_STATE_CODE(); 1224 assert(bs->open_flags & BDRV_O_INACTIVE); 1225 return 0; 1226 } 1227 1228 static bool bdrv_child_cb_change_aio_ctx(BdrvChild *child, AioContext *ctx, 1229 GHashTable *visited, Transaction *tran, 1230 Error **errp) 1231 { 1232 BlockDriverState *bs = child->opaque; 1233 return bdrv_change_aio_context(bs, ctx, visited, tran, errp); 1234 } 1235 1236 /* 1237 * Returns the options and flags that a temporary snapshot should get, based on 1238 * the originally requested flags (the originally requested image will have 1239 * flags like a backing file) 1240 */ 1241 static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options, 1242 int parent_flags, QDict *parent_options) 1243 { 1244 GLOBAL_STATE_CODE(); 1245 *child_flags = (parent_flags & ~BDRV_O_SNAPSHOT) | BDRV_O_TEMPORARY; 1246 1247 /* For temporary files, unconditional cache=unsafe is fine */ 1248 qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off"); 1249 qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on"); 1250 1251 /* Copy the read-only and discard options from the parent */ 1252 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY); 1253 qdict_copy_default(child_options, parent_options, BDRV_OPT_DISCARD); 1254 1255 /* aio=native doesn't work for cache.direct=off, so disable it for the 1256 * temporary snapshot */ 1257 *child_flags &= ~BDRV_O_NATIVE_AIO; 1258 } 1259 1260 static void GRAPH_WRLOCK bdrv_backing_attach(BdrvChild *c) 1261 { 1262 BlockDriverState *parent = c->opaque; 1263 BlockDriverState *backing_hd = c->bs; 1264 1265 GLOBAL_STATE_CODE(); 1266 assert(!parent->backing_blocker); 1267 error_setg(&parent->backing_blocker, 1268 "node is used as backing hd of '%s'", 1269 bdrv_get_device_or_node_name(parent)); 1270 1271 bdrv_refresh_filename(backing_hd); 1272 1273 parent->open_flags &= ~BDRV_O_NO_BACKING; 1274 1275 bdrv_op_block_all(backing_hd, parent->backing_blocker); 1276 /* Otherwise we won't be able to commit or stream */ 1277 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET, 1278 parent->backing_blocker); 1279 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM, 1280 parent->backing_blocker); 1281 /* 1282 * We do backup in 3 ways: 1283 * 1. drive backup 1284 * The target bs is new opened, and the source is top BDS 1285 * 2. blockdev backup 1286 * Both the source and the target are top BDSes. 1287 * 3. internal backup(used for block replication) 1288 * Both the source and the target are backing file 1289 * 1290 * In case 1 and 2, neither the source nor the target is the backing file. 1291 * In case 3, we will block the top BDS, so there is only one block job 1292 * for the top BDS and its backing chain. 1293 */ 1294 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE, 1295 parent->backing_blocker); 1296 bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET, 1297 parent->backing_blocker); 1298 } 1299 1300 static void bdrv_backing_detach(BdrvChild *c) 1301 { 1302 BlockDriverState *parent = c->opaque; 1303 1304 GLOBAL_STATE_CODE(); 1305 assert(parent->backing_blocker); 1306 bdrv_op_unblock_all(c->bs, parent->backing_blocker); 1307 error_free(parent->backing_blocker); 1308 parent->backing_blocker = NULL; 1309 } 1310 1311 static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base, 1312 const char *filename, Error **errp) 1313 { 1314 BlockDriverState *parent = c->opaque; 1315 bool read_only = bdrv_is_read_only(parent); 1316 int ret; 1317 GLOBAL_STATE_CODE(); 1318 1319 if (read_only) { 1320 ret = bdrv_reopen_set_read_only(parent, false, errp); 1321 if (ret < 0) { 1322 return ret; 1323 } 1324 } 1325 1326 ret = bdrv_change_backing_file(parent, filename, 1327 base->drv ? base->drv->format_name : "", 1328 false); 1329 if (ret < 0) { 1330 error_setg_errno(errp, -ret, "Could not update backing file link"); 1331 } 1332 1333 if (read_only) { 1334 bdrv_reopen_set_read_only(parent, true, NULL); 1335 } 1336 1337 return ret; 1338 } 1339 1340 /* 1341 * Returns the options and flags that a generic child of a BDS should 1342 * get, based on the given options and flags for the parent BDS. 1343 */ 1344 static void bdrv_inherited_options(BdrvChildRole role, bool parent_is_format, 1345 int *child_flags, QDict *child_options, 1346 int parent_flags, QDict *parent_options) 1347 { 1348 int flags = parent_flags; 1349 GLOBAL_STATE_CODE(); 1350 1351 /* 1352 * First, decide whether to set, clear, or leave BDRV_O_PROTOCOL. 1353 * Generally, the question to answer is: Should this child be 1354 * format-probed by default? 1355 */ 1356 1357 /* 1358 * Pure and non-filtered data children of non-format nodes should 1359 * be probed by default (even when the node itself has BDRV_O_PROTOCOL 1360 * set). This only affects a very limited set of drivers (namely 1361 * quorum and blkverify when this comment was written). 1362 * Force-clear BDRV_O_PROTOCOL then. 1363 */ 1364 if (!parent_is_format && 1365 (role & BDRV_CHILD_DATA) && 1366 !(role & (BDRV_CHILD_METADATA | BDRV_CHILD_FILTERED))) 1367 { 1368 flags &= ~BDRV_O_PROTOCOL; 1369 } 1370 1371 /* 1372 * All children of format nodes (except for COW children) and all 1373 * metadata children in general should never be format-probed. 1374 * Force-set BDRV_O_PROTOCOL then. 1375 */ 1376 if ((parent_is_format && !(role & BDRV_CHILD_COW)) || 1377 (role & BDRV_CHILD_METADATA)) 1378 { 1379 flags |= BDRV_O_PROTOCOL; 1380 } 1381 1382 /* 1383 * If the cache mode isn't explicitly set, inherit direct and no-flush from 1384 * the parent. 1385 */ 1386 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT); 1387 qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH); 1388 qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE); 1389 1390 if (role & BDRV_CHILD_COW) { 1391 /* backing files are opened read-only by default */ 1392 qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on"); 1393 qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off"); 1394 } else { 1395 /* Inherit the read-only option from the parent if it's not set */ 1396 qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY); 1397 qdict_copy_default(child_options, parent_options, 1398 BDRV_OPT_AUTO_READ_ONLY); 1399 } 1400 1401 /* 1402 * bdrv_co_pdiscard() respects unmap policy for the parent, so we 1403 * can default to enable it on lower layers regardless of the 1404 * parent option. 1405 */ 1406 qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap"); 1407 1408 /* Clear flags that only apply to the top layer */ 1409 flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ); 1410 1411 if (role & BDRV_CHILD_METADATA) { 1412 flags &= ~BDRV_O_NO_IO; 1413 } 1414 if (role & BDRV_CHILD_COW) { 1415 flags &= ~BDRV_O_TEMPORARY; 1416 } 1417 1418 *child_flags = flags; 1419 } 1420 1421 static void GRAPH_WRLOCK bdrv_child_cb_attach(BdrvChild *child) 1422 { 1423 BlockDriverState *bs = child->opaque; 1424 1425 assert_bdrv_graph_writable(); 1426 QLIST_INSERT_HEAD(&bs->children, child, next); 1427 if (bs->drv->is_filter || (child->role & BDRV_CHILD_FILTERED)) { 1428 /* 1429 * Here we handle filters and block/raw-format.c when it behave like 1430 * filter. They generally have a single PRIMARY child, which is also the 1431 * FILTERED child, and that they may have multiple more children, which 1432 * are neither PRIMARY nor FILTERED. And never we have a COW child here. 1433 * So bs->file will be the PRIMARY child, unless the PRIMARY child goes 1434 * into bs->backing on exceptional cases; and bs->backing will be 1435 * nothing else. 1436 */ 1437 assert(!(child->role & BDRV_CHILD_COW)); 1438 if (child->role & BDRV_CHILD_PRIMARY) { 1439 assert(child->role & BDRV_CHILD_FILTERED); 1440 assert(!bs->backing); 1441 assert(!bs->file); 1442 1443 if (bs->drv->filtered_child_is_backing) { 1444 bs->backing = child; 1445 } else { 1446 bs->file = child; 1447 } 1448 } else { 1449 assert(!(child->role & BDRV_CHILD_FILTERED)); 1450 } 1451 } else if (child->role & BDRV_CHILD_COW) { 1452 assert(bs->drv->supports_backing); 1453 assert(!(child->role & BDRV_CHILD_PRIMARY)); 1454 assert(!bs->backing); 1455 bs->backing = child; 1456 bdrv_backing_attach(child); 1457 } else if (child->role & BDRV_CHILD_PRIMARY) { 1458 assert(!bs->file); 1459 bs->file = child; 1460 } 1461 } 1462 1463 static void GRAPH_WRLOCK bdrv_child_cb_detach(BdrvChild *child) 1464 { 1465 BlockDriverState *bs = child->opaque; 1466 1467 if (child->role & BDRV_CHILD_COW) { 1468 bdrv_backing_detach(child); 1469 } 1470 1471 assert_bdrv_graph_writable(); 1472 QLIST_REMOVE(child, next); 1473 if (child == bs->backing) { 1474 assert(child != bs->file); 1475 bs->backing = NULL; 1476 } else if (child == bs->file) { 1477 bs->file = NULL; 1478 } 1479 } 1480 1481 static int bdrv_child_cb_update_filename(BdrvChild *c, BlockDriverState *base, 1482 const char *filename, Error **errp) 1483 { 1484 if (c->role & BDRV_CHILD_COW) { 1485 return bdrv_backing_update_filename(c, base, filename, errp); 1486 } 1487 return 0; 1488 } 1489 1490 AioContext *child_of_bds_get_parent_aio_context(BdrvChild *c) 1491 { 1492 BlockDriverState *bs = c->opaque; 1493 IO_CODE(); 1494 1495 return bdrv_get_aio_context(bs); 1496 } 1497 1498 const BdrvChildClass child_of_bds = { 1499 .parent_is_bds = true, 1500 .get_parent_desc = bdrv_child_get_parent_desc, 1501 .inherit_options = bdrv_inherited_options, 1502 .drained_begin = bdrv_child_cb_drained_begin, 1503 .drained_poll = bdrv_child_cb_drained_poll, 1504 .drained_end = bdrv_child_cb_drained_end, 1505 .attach = bdrv_child_cb_attach, 1506 .detach = bdrv_child_cb_detach, 1507 .inactivate = bdrv_child_cb_inactivate, 1508 .change_aio_ctx = bdrv_child_cb_change_aio_ctx, 1509 .update_filename = bdrv_child_cb_update_filename, 1510 .get_parent_aio_context = child_of_bds_get_parent_aio_context, 1511 }; 1512 1513 AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c) 1514 { 1515 IO_CODE(); 1516 return c->klass->get_parent_aio_context(c); 1517 } 1518 1519 static int bdrv_open_flags(BlockDriverState *bs, int flags) 1520 { 1521 int open_flags = flags; 1522 GLOBAL_STATE_CODE(); 1523 1524 /* 1525 * Clear flags that are internal to the block layer before opening the 1526 * image. 1527 */ 1528 open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_PROTOCOL); 1529 1530 return open_flags; 1531 } 1532 1533 static void update_flags_from_options(int *flags, QemuOpts *opts) 1534 { 1535 GLOBAL_STATE_CODE(); 1536 1537 *flags &= ~(BDRV_O_CACHE_MASK | BDRV_O_RDWR | BDRV_O_AUTO_RDONLY); 1538 1539 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) { 1540 *flags |= BDRV_O_NO_FLUSH; 1541 } 1542 1543 if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_DIRECT, false)) { 1544 *flags |= BDRV_O_NOCACHE; 1545 } 1546 1547 if (!qemu_opt_get_bool_del(opts, BDRV_OPT_READ_ONLY, false)) { 1548 *flags |= BDRV_O_RDWR; 1549 } 1550 1551 if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) { 1552 *flags |= BDRV_O_AUTO_RDONLY; 1553 } 1554 } 1555 1556 static void update_options_from_flags(QDict *options, int flags) 1557 { 1558 GLOBAL_STATE_CODE(); 1559 if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) { 1560 qdict_put_bool(options, BDRV_OPT_CACHE_DIRECT, flags & BDRV_O_NOCACHE); 1561 } 1562 if (!qdict_haskey(options, BDRV_OPT_CACHE_NO_FLUSH)) { 1563 qdict_put_bool(options, BDRV_OPT_CACHE_NO_FLUSH, 1564 flags & BDRV_O_NO_FLUSH); 1565 } 1566 if (!qdict_haskey(options, BDRV_OPT_READ_ONLY)) { 1567 qdict_put_bool(options, BDRV_OPT_READ_ONLY, !(flags & BDRV_O_RDWR)); 1568 } 1569 if (!qdict_haskey(options, BDRV_OPT_AUTO_READ_ONLY)) { 1570 qdict_put_bool(options, BDRV_OPT_AUTO_READ_ONLY, 1571 flags & BDRV_O_AUTO_RDONLY); 1572 } 1573 } 1574 1575 static void bdrv_assign_node_name(BlockDriverState *bs, 1576 const char *node_name, 1577 Error **errp) 1578 { 1579 char *gen_node_name = NULL; 1580 GLOBAL_STATE_CODE(); 1581 1582 if (!node_name) { 1583 node_name = gen_node_name = id_generate(ID_BLOCK); 1584 } else if (!id_wellformed(node_name)) { 1585 /* 1586 * Check for empty string or invalid characters, but not if it is 1587 * generated (generated names use characters not available to the user) 1588 */ 1589 error_setg(errp, "Invalid node-name: '%s'", node_name); 1590 return; 1591 } 1592 1593 /* takes care of avoiding namespaces collisions */ 1594 if (blk_by_name(node_name)) { 1595 error_setg(errp, "node-name=%s is conflicting with a device id", 1596 node_name); 1597 goto out; 1598 } 1599 1600 /* takes care of avoiding duplicates node names */ 1601 if (bdrv_find_node(node_name)) { 1602 error_setg(errp, "Duplicate nodes with node-name='%s'", node_name); 1603 goto out; 1604 } 1605 1606 /* Make sure that the node name isn't truncated */ 1607 if (strlen(node_name) >= sizeof(bs->node_name)) { 1608 error_setg(errp, "Node name too long"); 1609 goto out; 1610 } 1611 1612 /* copy node name into the bs and insert it into the graph list */ 1613 pstrcpy(bs->node_name, sizeof(bs->node_name), node_name); 1614 QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs, node_list); 1615 out: 1616 g_free(gen_node_name); 1617 } 1618 1619 /* 1620 * The caller must always hold @bs AioContext lock, because this function calls 1621 * bdrv_refresh_total_sectors() which polls when called from non-coroutine 1622 * context. 1623 */ 1624 static int no_coroutine_fn GRAPH_UNLOCKED 1625 bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, const char *node_name, 1626 QDict *options, int open_flags, Error **errp) 1627 { 1628 AioContext *ctx; 1629 Error *local_err = NULL; 1630 int i, ret; 1631 GLOBAL_STATE_CODE(); 1632 1633 bdrv_assign_node_name(bs, node_name, &local_err); 1634 if (local_err) { 1635 error_propagate(errp, local_err); 1636 return -EINVAL; 1637 } 1638 1639 bs->drv = drv; 1640 bs->opaque = g_malloc0(drv->instance_size); 1641 1642 if (drv->bdrv_file_open) { 1643 assert(!drv->bdrv_needs_filename || bs->filename[0]); 1644 ret = drv->bdrv_file_open(bs, options, open_flags, &local_err); 1645 } else if (drv->bdrv_open) { 1646 ret = drv->bdrv_open(bs, options, open_flags, &local_err); 1647 } else { 1648 ret = 0; 1649 } 1650 1651 if (ret < 0) { 1652 if (local_err) { 1653 error_propagate(errp, local_err); 1654 } else if (bs->filename[0]) { 1655 error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename); 1656 } else { 1657 error_setg_errno(errp, -ret, "Could not open image"); 1658 } 1659 goto open_failed; 1660 } 1661 1662 assert(!(bs->supported_read_flags & ~BDRV_REQ_MASK)); 1663 assert(!(bs->supported_write_flags & ~BDRV_REQ_MASK)); 1664 1665 /* 1666 * Always allow the BDRV_REQ_REGISTERED_BUF optimization hint. This saves 1667 * drivers that pass read/write requests through to a child the trouble of 1668 * declaring support explicitly. 1669 * 1670 * Drivers must not propagate this flag accidentally when they initiate I/O 1671 * to a bounce buffer. That case should be rare though. 1672 */ 1673 bs->supported_read_flags |= BDRV_REQ_REGISTERED_BUF; 1674 bs->supported_write_flags |= BDRV_REQ_REGISTERED_BUF; 1675 1676 /* Get the context after .bdrv_open, it can change the context */ 1677 ctx = bdrv_get_aio_context(bs); 1678 aio_context_acquire(ctx); 1679 1680 ret = bdrv_refresh_total_sectors(bs, bs->total_sectors); 1681 if (ret < 0) { 1682 error_setg_errno(errp, -ret, "Could not refresh total sector count"); 1683 aio_context_release(ctx); 1684 return ret; 1685 } 1686 1687 bdrv_graph_rdlock_main_loop(); 1688 bdrv_refresh_limits(bs, NULL, &local_err); 1689 bdrv_graph_rdunlock_main_loop(); 1690 aio_context_release(ctx); 1691 1692 if (local_err) { 1693 error_propagate(errp, local_err); 1694 return -EINVAL; 1695 } 1696 1697 assert(bdrv_opt_mem_align(bs) != 0); 1698 assert(bdrv_min_mem_align(bs) != 0); 1699 assert(is_power_of_2(bs->bl.request_alignment)); 1700 1701 for (i = 0; i < bs->quiesce_counter; i++) { 1702 if (drv->bdrv_drain_begin) { 1703 drv->bdrv_drain_begin(bs); 1704 } 1705 } 1706 1707 return 0; 1708 open_failed: 1709 bs->drv = NULL; 1710 if (bs->file != NULL) { 1711 bdrv_graph_wrlock(NULL); 1712 bdrv_unref_child(bs, bs->file); 1713 bdrv_graph_wrunlock(); 1714 assert(!bs->file); 1715 } 1716 g_free(bs->opaque); 1717 bs->opaque = NULL; 1718 return ret; 1719 } 1720 1721 /* 1722 * Create and open a block node. 1723 * 1724 * @options is a QDict of options to pass to the block drivers, or NULL for an 1725 * empty set of options. The reference to the QDict belongs to the block layer 1726 * after the call (even on failure), so if the caller intends to reuse the 1727 * dictionary, it needs to use qobject_ref() before calling bdrv_open. 1728 */ 1729 BlockDriverState *bdrv_new_open_driver_opts(BlockDriver *drv, 1730 const char *node_name, 1731 QDict *options, int flags, 1732 Error **errp) 1733 { 1734 BlockDriverState *bs; 1735 int ret; 1736 1737 GLOBAL_STATE_CODE(); 1738 1739 bs = bdrv_new(); 1740 bs->open_flags = flags; 1741 bs->options = options ?: qdict_new(); 1742 bs->explicit_options = qdict_clone_shallow(bs->options); 1743 bs->opaque = NULL; 1744 1745 update_options_from_flags(bs->options, flags); 1746 1747 ret = bdrv_open_driver(bs, drv, node_name, bs->options, flags, errp); 1748 if (ret < 0) { 1749 qobject_unref(bs->explicit_options); 1750 bs->explicit_options = NULL; 1751 qobject_unref(bs->options); 1752 bs->options = NULL; 1753 bdrv_unref(bs); 1754 return NULL; 1755 } 1756 1757 return bs; 1758 } 1759 1760 /* Create and open a block node. */ 1761 BlockDriverState *bdrv_new_open_driver(BlockDriver *drv, const char *node_name, 1762 int flags, Error **errp) 1763 { 1764 GLOBAL_STATE_CODE(); 1765 return bdrv_new_open_driver_opts(drv, node_name, NULL, flags, errp); 1766 } 1767 1768 QemuOptsList bdrv_runtime_opts = { 1769 .name = "bdrv_common", 1770 .head = QTAILQ_HEAD_INITIALIZER(bdrv_runtime_opts.head), 1771 .desc = { 1772 { 1773 .name = "node-name", 1774 .type = QEMU_OPT_STRING, 1775 .help = "Node name of the block device node", 1776 }, 1777 { 1778 .name = "driver", 1779 .type = QEMU_OPT_STRING, 1780 .help = "Block driver to use for the node", 1781 }, 1782 { 1783 .name = BDRV_OPT_CACHE_DIRECT, 1784 .type = QEMU_OPT_BOOL, 1785 .help = "Bypass software writeback cache on the host", 1786 }, 1787 { 1788 .name = BDRV_OPT_CACHE_NO_FLUSH, 1789 .type = QEMU_OPT_BOOL, 1790 .help = "Ignore flush requests", 1791 }, 1792 { 1793 .name = BDRV_OPT_READ_ONLY, 1794 .type = QEMU_OPT_BOOL, 1795 .help = "Node is opened in read-only mode", 1796 }, 1797 { 1798 .name = BDRV_OPT_AUTO_READ_ONLY, 1799 .type = QEMU_OPT_BOOL, 1800 .help = "Node can become read-only if opening read-write fails", 1801 }, 1802 { 1803 .name = "detect-zeroes", 1804 .type = QEMU_OPT_STRING, 1805 .help = "try to optimize zero writes (off, on, unmap)", 1806 }, 1807 { 1808 .name = BDRV_OPT_DISCARD, 1809 .type = QEMU_OPT_STRING, 1810 .help = "discard operation (ignore/off, unmap/on)", 1811 }, 1812 { 1813 .name = BDRV_OPT_FORCE_SHARE, 1814 .type = QEMU_OPT_BOOL, 1815 .help = "always accept other writers (default: off)", 1816 }, 1817 { /* end of list */ } 1818 }, 1819 }; 1820 1821 QemuOptsList bdrv_create_opts_simple = { 1822 .name = "simple-create-opts", 1823 .head = QTAILQ_HEAD_INITIALIZER(bdrv_create_opts_simple.head), 1824 .desc = { 1825 { 1826 .name = BLOCK_OPT_SIZE, 1827 .type = QEMU_OPT_SIZE, 1828 .help = "Virtual disk size" 1829 }, 1830 { 1831 .name = BLOCK_OPT_PREALLOC, 1832 .type = QEMU_OPT_STRING, 1833 .help = "Preallocation mode (allowed values: off)" 1834 }, 1835 { /* end of list */ } 1836 } 1837 }; 1838 1839 /* 1840 * Common part for opening disk images and files 1841 * 1842 * Removes all processed options from *options. 1843 */ 1844 static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file, 1845 QDict *options, Error **errp) 1846 { 1847 int ret, open_flags; 1848 const char *filename; 1849 const char *driver_name = NULL; 1850 const char *node_name = NULL; 1851 const char *discard; 1852 QemuOpts *opts; 1853 BlockDriver *drv; 1854 Error *local_err = NULL; 1855 bool ro; 1856 1857 assert(bs->file == NULL); 1858 assert(options != NULL && bs->options != options); 1859 GLOBAL_STATE_CODE(); 1860 1861 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); 1862 if (!qemu_opts_absorb_qdict(opts, options, errp)) { 1863 ret = -EINVAL; 1864 goto fail_opts; 1865 } 1866 1867 update_flags_from_options(&bs->open_flags, opts); 1868 1869 driver_name = qemu_opt_get(opts, "driver"); 1870 drv = bdrv_find_format(driver_name); 1871 assert(drv != NULL); 1872 1873 bs->force_share = qemu_opt_get_bool(opts, BDRV_OPT_FORCE_SHARE, false); 1874 1875 if (bs->force_share && (bs->open_flags & BDRV_O_RDWR)) { 1876 error_setg(errp, 1877 BDRV_OPT_FORCE_SHARE 1878 "=on can only be used with read-only images"); 1879 ret = -EINVAL; 1880 goto fail_opts; 1881 } 1882 1883 if (file != NULL) { 1884 bdrv_graph_rdlock_main_loop(); 1885 bdrv_refresh_filename(blk_bs(file)); 1886 bdrv_graph_rdunlock_main_loop(); 1887 1888 filename = blk_bs(file)->filename; 1889 } else { 1890 /* 1891 * Caution: while qdict_get_try_str() is fine, getting 1892 * non-string types would require more care. When @options 1893 * come from -blockdev or blockdev_add, its members are typed 1894 * according to the QAPI schema, but when they come from 1895 * -drive, they're all QString. 1896 */ 1897 filename = qdict_get_try_str(options, "filename"); 1898 } 1899 1900 if (drv->bdrv_needs_filename && (!filename || !filename[0])) { 1901 error_setg(errp, "The '%s' block driver requires a file name", 1902 drv->format_name); 1903 ret = -EINVAL; 1904 goto fail_opts; 1905 } 1906 1907 trace_bdrv_open_common(bs, filename ?: "", bs->open_flags, 1908 drv->format_name); 1909 1910 ro = bdrv_is_read_only(bs); 1911 1912 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, ro)) { 1913 if (!ro && bdrv_is_whitelisted(drv, true)) { 1914 bdrv_graph_rdlock_main_loop(); 1915 ret = bdrv_apply_auto_read_only(bs, NULL, NULL); 1916 bdrv_graph_rdunlock_main_loop(); 1917 } else { 1918 ret = -ENOTSUP; 1919 } 1920 if (ret < 0) { 1921 error_setg(errp, 1922 !ro && bdrv_is_whitelisted(drv, true) 1923 ? "Driver '%s' can only be used for read-only devices" 1924 : "Driver '%s' is not whitelisted", 1925 drv->format_name); 1926 goto fail_opts; 1927 } 1928 } 1929 1930 /* bdrv_new() and bdrv_close() make it so */ 1931 assert(qatomic_read(&bs->copy_on_read) == 0); 1932 1933 if (bs->open_flags & BDRV_O_COPY_ON_READ) { 1934 if (!ro) { 1935 bdrv_enable_copy_on_read(bs); 1936 } else { 1937 error_setg(errp, "Can't use copy-on-read on read-only device"); 1938 ret = -EINVAL; 1939 goto fail_opts; 1940 } 1941 } 1942 1943 discard = qemu_opt_get(opts, BDRV_OPT_DISCARD); 1944 if (discard != NULL) { 1945 if (bdrv_parse_discard_flags(discard, &bs->open_flags) != 0) { 1946 error_setg(errp, "Invalid discard option"); 1947 ret = -EINVAL; 1948 goto fail_opts; 1949 } 1950 } 1951 1952 bs->detect_zeroes = 1953 bdrv_parse_detect_zeroes(opts, bs->open_flags, &local_err); 1954 if (local_err) { 1955 error_propagate(errp, local_err); 1956 ret = -EINVAL; 1957 goto fail_opts; 1958 } 1959 1960 if (filename != NULL) { 1961 pstrcpy(bs->filename, sizeof(bs->filename), filename); 1962 } else { 1963 bs->filename[0] = '\0'; 1964 } 1965 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->filename); 1966 1967 /* Open the image, either directly or using a protocol */ 1968 open_flags = bdrv_open_flags(bs, bs->open_flags); 1969 node_name = qemu_opt_get(opts, "node-name"); 1970 1971 assert(!drv->bdrv_file_open || file == NULL); 1972 ret = bdrv_open_driver(bs, drv, node_name, options, open_flags, errp); 1973 if (ret < 0) { 1974 goto fail_opts; 1975 } 1976 1977 qemu_opts_del(opts); 1978 return 0; 1979 1980 fail_opts: 1981 qemu_opts_del(opts); 1982 return ret; 1983 } 1984 1985 static QDict *parse_json_filename(const char *filename, Error **errp) 1986 { 1987 QObject *options_obj; 1988 QDict *options; 1989 int ret; 1990 GLOBAL_STATE_CODE(); 1991 1992 ret = strstart(filename, "json:", &filename); 1993 assert(ret); 1994 1995 options_obj = qobject_from_json(filename, errp); 1996 if (!options_obj) { 1997 error_prepend(errp, "Could not parse the JSON options: "); 1998 return NULL; 1999 } 2000 2001 options = qobject_to(QDict, options_obj); 2002 if (!options) { 2003 qobject_unref(options_obj); 2004 error_setg(errp, "Invalid JSON object given"); 2005 return NULL; 2006 } 2007 2008 qdict_flatten(options); 2009 2010 return options; 2011 } 2012 2013 static void parse_json_protocol(QDict *options, const char **pfilename, 2014 Error **errp) 2015 { 2016 QDict *json_options; 2017 Error *local_err = NULL; 2018 GLOBAL_STATE_CODE(); 2019 2020 /* Parse json: pseudo-protocol */ 2021 if (!*pfilename || !g_str_has_prefix(*pfilename, "json:")) { 2022 return; 2023 } 2024 2025 json_options = parse_json_filename(*pfilename, &local_err); 2026 if (local_err) { 2027 error_propagate(errp, local_err); 2028 return; 2029 } 2030 2031 /* Options given in the filename have lower priority than options 2032 * specified directly */ 2033 qdict_join(options, json_options, false); 2034 qobject_unref(json_options); 2035 *pfilename = NULL; 2036 } 2037 2038 /* 2039 * Fills in default options for opening images and converts the legacy 2040 * filename/flags pair to option QDict entries. 2041 * The BDRV_O_PROTOCOL flag in *flags will be set or cleared accordingly if a 2042 * block driver has been specified explicitly. 2043 */ 2044 static int bdrv_fill_options(QDict **options, const char *filename, 2045 int *flags, Error **errp) 2046 { 2047 const char *drvname; 2048 bool protocol = *flags & BDRV_O_PROTOCOL; 2049 bool parse_filename = false; 2050 BlockDriver *drv = NULL; 2051 Error *local_err = NULL; 2052 2053 GLOBAL_STATE_CODE(); 2054 2055 /* 2056 * Caution: while qdict_get_try_str() is fine, getting non-string 2057 * types would require more care. When @options come from 2058 * -blockdev or blockdev_add, its members are typed according to 2059 * the QAPI schema, but when they come from -drive, they're all 2060 * QString. 2061 */ 2062 drvname = qdict_get_try_str(*options, "driver"); 2063 if (drvname) { 2064 drv = bdrv_find_format(drvname); 2065 if (!drv) { 2066 error_setg(errp, "Unknown driver '%s'", drvname); 2067 return -ENOENT; 2068 } 2069 /* If the user has explicitly specified the driver, this choice should 2070 * override the BDRV_O_PROTOCOL flag */ 2071 protocol = drv->bdrv_file_open; 2072 } 2073 2074 if (protocol) { 2075 *flags |= BDRV_O_PROTOCOL; 2076 } else { 2077 *flags &= ~BDRV_O_PROTOCOL; 2078 } 2079 2080 /* Translate cache options from flags into options */ 2081 update_options_from_flags(*options, *flags); 2082 2083 /* Fetch the file name from the options QDict if necessary */ 2084 if (protocol && filename) { 2085 if (!qdict_haskey(*options, "filename")) { 2086 qdict_put_str(*options, "filename", filename); 2087 parse_filename = true; 2088 } else { 2089 error_setg(errp, "Can't specify 'file' and 'filename' options at " 2090 "the same time"); 2091 return -EINVAL; 2092 } 2093 } 2094 2095 /* Find the right block driver */ 2096 /* See cautionary note on accessing @options above */ 2097 filename = qdict_get_try_str(*options, "filename"); 2098 2099 if (!drvname && protocol) { 2100 if (filename) { 2101 drv = bdrv_find_protocol(filename, parse_filename, errp); 2102 if (!drv) { 2103 return -EINVAL; 2104 } 2105 2106 drvname = drv->format_name; 2107 qdict_put_str(*options, "driver", drvname); 2108 } else { 2109 error_setg(errp, "Must specify either driver or file"); 2110 return -EINVAL; 2111 } 2112 } 2113 2114 assert(drv || !protocol); 2115 2116 /* Driver-specific filename parsing */ 2117 if (drv && drv->bdrv_parse_filename && parse_filename) { 2118 drv->bdrv_parse_filename(filename, *options, &local_err); 2119 if (local_err) { 2120 error_propagate(errp, local_err); 2121 return -EINVAL; 2122 } 2123 2124 if (!drv->bdrv_needs_filename) { 2125 qdict_del(*options, "filename"); 2126 } 2127 } 2128 2129 return 0; 2130 } 2131 2132 typedef struct BlockReopenQueueEntry { 2133 bool prepared; 2134 BDRVReopenState state; 2135 QTAILQ_ENTRY(BlockReopenQueueEntry) entry; 2136 } BlockReopenQueueEntry; 2137 2138 /* 2139 * Return the flags that @bs will have after the reopens in @q have 2140 * successfully completed. If @q is NULL (or @bs is not contained in @q), 2141 * return the current flags. 2142 */ 2143 static int bdrv_reopen_get_flags(BlockReopenQueue *q, BlockDriverState *bs) 2144 { 2145 BlockReopenQueueEntry *entry; 2146 2147 if (q != NULL) { 2148 QTAILQ_FOREACH(entry, q, entry) { 2149 if (entry->state.bs == bs) { 2150 return entry->state.flags; 2151 } 2152 } 2153 } 2154 2155 return bs->open_flags; 2156 } 2157 2158 /* Returns whether the image file can be written to after the reopen queue @q 2159 * has been successfully applied, or right now if @q is NULL. */ 2160 static bool bdrv_is_writable_after_reopen(BlockDriverState *bs, 2161 BlockReopenQueue *q) 2162 { 2163 int flags = bdrv_reopen_get_flags(q, bs); 2164 2165 return (flags & (BDRV_O_RDWR | BDRV_O_INACTIVE)) == BDRV_O_RDWR; 2166 } 2167 2168 /* 2169 * Return whether the BDS can be written to. This is not necessarily 2170 * the same as !bdrv_is_read_only(bs), as inactivated images may not 2171 * be written to but do not count as read-only images. 2172 */ 2173 bool bdrv_is_writable(BlockDriverState *bs) 2174 { 2175 IO_CODE(); 2176 return bdrv_is_writable_after_reopen(bs, NULL); 2177 } 2178 2179 static char *bdrv_child_user_desc(BdrvChild *c) 2180 { 2181 GLOBAL_STATE_CODE(); 2182 return c->klass->get_parent_desc(c); 2183 } 2184 2185 /* 2186 * Check that @a allows everything that @b needs. @a and @b must reference same 2187 * child node. 2188 */ 2189 static bool bdrv_a_allow_b(BdrvChild *a, BdrvChild *b, Error **errp) 2190 { 2191 const char *child_bs_name; 2192 g_autofree char *a_user = NULL; 2193 g_autofree char *b_user = NULL; 2194 g_autofree char *perms = NULL; 2195 2196 assert(a->bs); 2197 assert(a->bs == b->bs); 2198 GLOBAL_STATE_CODE(); 2199 2200 if ((b->perm & a->shared_perm) == b->perm) { 2201 return true; 2202 } 2203 2204 child_bs_name = bdrv_get_node_name(b->bs); 2205 a_user = bdrv_child_user_desc(a); 2206 b_user = bdrv_child_user_desc(b); 2207 perms = bdrv_perm_names(b->perm & ~a->shared_perm); 2208 2209 error_setg(errp, "Permission conflict on node '%s': permissions '%s' are " 2210 "both required by %s (uses node '%s' as '%s' child) and " 2211 "unshared by %s (uses node '%s' as '%s' child).", 2212 child_bs_name, perms, 2213 b_user, child_bs_name, b->name, 2214 a_user, child_bs_name, a->name); 2215 2216 return false; 2217 } 2218 2219 static bool GRAPH_RDLOCK 2220 bdrv_parent_perms_conflict(BlockDriverState *bs, Error **errp) 2221 { 2222 BdrvChild *a, *b; 2223 GLOBAL_STATE_CODE(); 2224 2225 /* 2226 * During the loop we'll look at each pair twice. That's correct because 2227 * bdrv_a_allow_b() is asymmetric and we should check each pair in both 2228 * directions. 2229 */ 2230 QLIST_FOREACH(a, &bs->parents, next_parent) { 2231 QLIST_FOREACH(b, &bs->parents, next_parent) { 2232 if (a == b) { 2233 continue; 2234 } 2235 2236 if (!bdrv_a_allow_b(a, b, errp)) { 2237 return true; 2238 } 2239 } 2240 } 2241 2242 return false; 2243 } 2244 2245 static void GRAPH_RDLOCK 2246 bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs, 2247 BdrvChild *c, BdrvChildRole role, 2248 BlockReopenQueue *reopen_queue, 2249 uint64_t parent_perm, uint64_t parent_shared, 2250 uint64_t *nperm, uint64_t *nshared) 2251 { 2252 assert(bs->drv && bs->drv->bdrv_child_perm); 2253 GLOBAL_STATE_CODE(); 2254 bs->drv->bdrv_child_perm(bs, c, role, reopen_queue, 2255 parent_perm, parent_shared, 2256 nperm, nshared); 2257 /* TODO Take force_share from reopen_queue */ 2258 if (child_bs && child_bs->force_share) { 2259 *nshared = BLK_PERM_ALL; 2260 } 2261 } 2262 2263 /* 2264 * Adds the whole subtree of @bs (including @bs itself) to the @list (except for 2265 * nodes that are already in the @list, of course) so that final list is 2266 * topologically sorted. Return the result (GSList @list object is updated, so 2267 * don't use old reference after function call). 2268 * 2269 * On function start @list must be already topologically sorted and for any node 2270 * in the @list the whole subtree of the node must be in the @list as well. The 2271 * simplest way to satisfy this criteria: use only result of 2272 * bdrv_topological_dfs() or NULL as @list parameter. 2273 */ 2274 static GSList * GRAPH_RDLOCK 2275 bdrv_topological_dfs(GSList *list, GHashTable *found, BlockDriverState *bs) 2276 { 2277 BdrvChild *child; 2278 g_autoptr(GHashTable) local_found = NULL; 2279 2280 GLOBAL_STATE_CODE(); 2281 2282 if (!found) { 2283 assert(!list); 2284 found = local_found = g_hash_table_new(NULL, NULL); 2285 } 2286 2287 if (g_hash_table_contains(found, bs)) { 2288 return list; 2289 } 2290 g_hash_table_add(found, bs); 2291 2292 QLIST_FOREACH(child, &bs->children, next) { 2293 list = bdrv_topological_dfs(list, found, child->bs); 2294 } 2295 2296 return g_slist_prepend(list, bs); 2297 } 2298 2299 typedef struct BdrvChildSetPermState { 2300 BdrvChild *child; 2301 uint64_t old_perm; 2302 uint64_t old_shared_perm; 2303 } BdrvChildSetPermState; 2304 2305 static void bdrv_child_set_perm_abort(void *opaque) 2306 { 2307 BdrvChildSetPermState *s = opaque; 2308 2309 GLOBAL_STATE_CODE(); 2310 2311 s->child->perm = s->old_perm; 2312 s->child->shared_perm = s->old_shared_perm; 2313 } 2314 2315 static TransactionActionDrv bdrv_child_set_pem_drv = { 2316 .abort = bdrv_child_set_perm_abort, 2317 .clean = g_free, 2318 }; 2319 2320 static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm, 2321 uint64_t shared, Transaction *tran) 2322 { 2323 BdrvChildSetPermState *s = g_new(BdrvChildSetPermState, 1); 2324 GLOBAL_STATE_CODE(); 2325 2326 *s = (BdrvChildSetPermState) { 2327 .child = c, 2328 .old_perm = c->perm, 2329 .old_shared_perm = c->shared_perm, 2330 }; 2331 2332 c->perm = perm; 2333 c->shared_perm = shared; 2334 2335 tran_add(tran, &bdrv_child_set_pem_drv, s); 2336 } 2337 2338 static void GRAPH_RDLOCK bdrv_drv_set_perm_commit(void *opaque) 2339 { 2340 BlockDriverState *bs = opaque; 2341 uint64_t cumulative_perms, cumulative_shared_perms; 2342 GLOBAL_STATE_CODE(); 2343 2344 if (bs->drv->bdrv_set_perm) { 2345 bdrv_get_cumulative_perm(bs, &cumulative_perms, 2346 &cumulative_shared_perms); 2347 bs->drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms); 2348 } 2349 } 2350 2351 static void GRAPH_RDLOCK bdrv_drv_set_perm_abort(void *opaque) 2352 { 2353 BlockDriverState *bs = opaque; 2354 GLOBAL_STATE_CODE(); 2355 2356 if (bs->drv->bdrv_abort_perm_update) { 2357 bs->drv->bdrv_abort_perm_update(bs); 2358 } 2359 } 2360 2361 TransactionActionDrv bdrv_drv_set_perm_drv = { 2362 .abort = bdrv_drv_set_perm_abort, 2363 .commit = bdrv_drv_set_perm_commit, 2364 }; 2365 2366 /* 2367 * After calling this function, the transaction @tran may only be completed 2368 * while holding a reader lock for the graph. 2369 */ 2370 static int GRAPH_RDLOCK 2371 bdrv_drv_set_perm(BlockDriverState *bs, uint64_t perm, uint64_t shared_perm, 2372 Transaction *tran, Error **errp) 2373 { 2374 GLOBAL_STATE_CODE(); 2375 if (!bs->drv) { 2376 return 0; 2377 } 2378 2379 if (bs->drv->bdrv_check_perm) { 2380 int ret = bs->drv->bdrv_check_perm(bs, perm, shared_perm, errp); 2381 if (ret < 0) { 2382 return ret; 2383 } 2384 } 2385 2386 if (tran) { 2387 tran_add(tran, &bdrv_drv_set_perm_drv, bs); 2388 } 2389 2390 return 0; 2391 } 2392 2393 typedef struct BdrvReplaceChildState { 2394 BdrvChild *child; 2395 BlockDriverState *old_bs; 2396 } BdrvReplaceChildState; 2397 2398 static void GRAPH_WRLOCK bdrv_replace_child_commit(void *opaque) 2399 { 2400 BdrvReplaceChildState *s = opaque; 2401 GLOBAL_STATE_CODE(); 2402 2403 bdrv_schedule_unref(s->old_bs); 2404 } 2405 2406 static void GRAPH_WRLOCK bdrv_replace_child_abort(void *opaque) 2407 { 2408 BdrvReplaceChildState *s = opaque; 2409 BlockDriverState *new_bs = s->child->bs; 2410 2411 GLOBAL_STATE_CODE(); 2412 assert_bdrv_graph_writable(); 2413 2414 /* old_bs reference is transparently moved from @s to @s->child */ 2415 if (!s->child->bs) { 2416 /* 2417 * The parents were undrained when removing old_bs from the child. New 2418 * requests can't have been made, though, because the child was empty. 2419 * 2420 * TODO Make bdrv_replace_child_noperm() transactionable to avoid 2421 * undraining the parent in the first place. Once this is done, having 2422 * new_bs drained when calling bdrv_replace_child_tran() is not a 2423 * requirement any more. 2424 */ 2425 bdrv_parent_drained_begin_single(s->child); 2426 assert(!bdrv_parent_drained_poll_single(s->child)); 2427 } 2428 assert(s->child->quiesced_parent); 2429 bdrv_replace_child_noperm(s->child, s->old_bs); 2430 2431 bdrv_unref(new_bs); 2432 } 2433 2434 static TransactionActionDrv bdrv_replace_child_drv = { 2435 .commit = bdrv_replace_child_commit, 2436 .abort = bdrv_replace_child_abort, 2437 .clean = g_free, 2438 }; 2439 2440 /* 2441 * bdrv_replace_child_tran 2442 * 2443 * Note: real unref of old_bs is done only on commit. 2444 * 2445 * Both @child->bs and @new_bs (if non-NULL) must be drained. @new_bs must be 2446 * kept drained until the transaction is completed. 2447 * 2448 * After calling this function, the transaction @tran may only be completed 2449 * while holding a writer lock for the graph. 2450 * 2451 * The function doesn't update permissions, caller is responsible for this. 2452 */ 2453 static void GRAPH_WRLOCK 2454 bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs, 2455 Transaction *tran) 2456 { 2457 BdrvReplaceChildState *s = g_new(BdrvReplaceChildState, 1); 2458 2459 assert(child->quiesced_parent); 2460 assert(!new_bs || new_bs->quiesce_counter); 2461 2462 *s = (BdrvReplaceChildState) { 2463 .child = child, 2464 .old_bs = child->bs, 2465 }; 2466 tran_add(tran, &bdrv_replace_child_drv, s); 2467 2468 if (new_bs) { 2469 bdrv_ref(new_bs); 2470 } 2471 2472 bdrv_replace_child_noperm(child, new_bs); 2473 /* old_bs reference is transparently moved from @child to @s */ 2474 } 2475 2476 /* 2477 * Refresh permissions in @bs subtree. The function is intended to be called 2478 * after some graph modification that was done without permission update. 2479 * 2480 * After calling this function, the transaction @tran may only be completed 2481 * while holding a reader lock for the graph. 2482 */ 2483 static int GRAPH_RDLOCK 2484 bdrv_node_refresh_perm(BlockDriverState *bs, BlockReopenQueue *q, 2485 Transaction *tran, Error **errp) 2486 { 2487 BlockDriver *drv = bs->drv; 2488 BdrvChild *c; 2489 int ret; 2490 uint64_t cumulative_perms, cumulative_shared_perms; 2491 GLOBAL_STATE_CODE(); 2492 2493 bdrv_get_cumulative_perm(bs, &cumulative_perms, &cumulative_shared_perms); 2494 2495 /* Write permissions never work with read-only images */ 2496 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) && 2497 !bdrv_is_writable_after_reopen(bs, q)) 2498 { 2499 if (!bdrv_is_writable_after_reopen(bs, NULL)) { 2500 error_setg(errp, "Block node is read-only"); 2501 } else { 2502 error_setg(errp, "Read-only block node '%s' cannot support " 2503 "read-write users", bdrv_get_node_name(bs)); 2504 } 2505 2506 return -EPERM; 2507 } 2508 2509 /* 2510 * Unaligned requests will automatically be aligned to bl.request_alignment 2511 * and without RESIZE we can't extend requests to write to space beyond the 2512 * end of the image, so it's required that the image size is aligned. 2513 */ 2514 if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) && 2515 !(cumulative_perms & BLK_PERM_RESIZE)) 2516 { 2517 if ((bs->total_sectors * BDRV_SECTOR_SIZE) % bs->bl.request_alignment) { 2518 error_setg(errp, "Cannot get 'write' permission without 'resize': " 2519 "Image size is not a multiple of request " 2520 "alignment"); 2521 return -EPERM; 2522 } 2523 } 2524 2525 /* Check this node */ 2526 if (!drv) { 2527 return 0; 2528 } 2529 2530 ret = bdrv_drv_set_perm(bs, cumulative_perms, cumulative_shared_perms, tran, 2531 errp); 2532 if (ret < 0) { 2533 return ret; 2534 } 2535 2536 /* Drivers that never have children can omit .bdrv_child_perm() */ 2537 if (!drv->bdrv_child_perm) { 2538 assert(QLIST_EMPTY(&bs->children)); 2539 return 0; 2540 } 2541 2542 /* Check all children */ 2543 QLIST_FOREACH(c, &bs->children, next) { 2544 uint64_t cur_perm, cur_shared; 2545 2546 bdrv_child_perm(bs, c->bs, c, c->role, q, 2547 cumulative_perms, cumulative_shared_perms, 2548 &cur_perm, &cur_shared); 2549 bdrv_child_set_perm(c, cur_perm, cur_shared, tran); 2550 } 2551 2552 return 0; 2553 } 2554 2555 /* 2556 * @list is a product of bdrv_topological_dfs() (may be called several times) - 2557 * a topologically sorted subgraph. 2558 * 2559 * After calling this function, the transaction @tran may only be completed 2560 * while holding a reader lock for the graph. 2561 */ 2562 static int GRAPH_RDLOCK 2563 bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran, 2564 Error **errp) 2565 { 2566 int ret; 2567 BlockDriverState *bs; 2568 GLOBAL_STATE_CODE(); 2569 2570 for ( ; list; list = list->next) { 2571 bs = list->data; 2572 2573 if (bdrv_parent_perms_conflict(bs, errp)) { 2574 return -EINVAL; 2575 } 2576 2577 ret = bdrv_node_refresh_perm(bs, q, tran, errp); 2578 if (ret < 0) { 2579 return ret; 2580 } 2581 } 2582 2583 return 0; 2584 } 2585 2586 /* 2587 * @list is any list of nodes. List is completed by all subtrees and 2588 * topologically sorted. It's not a problem if some node occurs in the @list 2589 * several times. 2590 * 2591 * After calling this function, the transaction @tran may only be completed 2592 * while holding a reader lock for the graph. 2593 */ 2594 static int GRAPH_RDLOCK 2595 bdrv_list_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran, 2596 Error **errp) 2597 { 2598 g_autoptr(GHashTable) found = g_hash_table_new(NULL, NULL); 2599 g_autoptr(GSList) refresh_list = NULL; 2600 2601 for ( ; list; list = list->next) { 2602 refresh_list = bdrv_topological_dfs(refresh_list, found, list->data); 2603 } 2604 2605 return bdrv_do_refresh_perms(refresh_list, q, tran, errp); 2606 } 2607 2608 void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm, 2609 uint64_t *shared_perm) 2610 { 2611 BdrvChild *c; 2612 uint64_t cumulative_perms = 0; 2613 uint64_t cumulative_shared_perms = BLK_PERM_ALL; 2614 2615 GLOBAL_STATE_CODE(); 2616 2617 QLIST_FOREACH(c, &bs->parents, next_parent) { 2618 cumulative_perms |= c->perm; 2619 cumulative_shared_perms &= c->shared_perm; 2620 } 2621 2622 *perm = cumulative_perms; 2623 *shared_perm = cumulative_shared_perms; 2624 } 2625 2626 char *bdrv_perm_names(uint64_t perm) 2627 { 2628 struct perm_name { 2629 uint64_t perm; 2630 const char *name; 2631 } permissions[] = { 2632 { BLK_PERM_CONSISTENT_READ, "consistent read" }, 2633 { BLK_PERM_WRITE, "write" }, 2634 { BLK_PERM_WRITE_UNCHANGED, "write unchanged" }, 2635 { BLK_PERM_RESIZE, "resize" }, 2636 { 0, NULL } 2637 }; 2638 2639 GString *result = g_string_sized_new(30); 2640 struct perm_name *p; 2641 2642 for (p = permissions; p->name; p++) { 2643 if (perm & p->perm) { 2644 if (result->len > 0) { 2645 g_string_append(result, ", "); 2646 } 2647 g_string_append(result, p->name); 2648 } 2649 } 2650 2651 return g_string_free(result, FALSE); 2652 } 2653 2654 2655 /* 2656 * @tran is allowed to be NULL. In this case no rollback is possible. 2657 * 2658 * After calling this function, the transaction @tran may only be completed 2659 * while holding a reader lock for the graph. 2660 */ 2661 static int GRAPH_RDLOCK 2662 bdrv_refresh_perms(BlockDriverState *bs, Transaction *tran, Error **errp) 2663 { 2664 int ret; 2665 Transaction *local_tran = NULL; 2666 g_autoptr(GSList) list = bdrv_topological_dfs(NULL, NULL, bs); 2667 GLOBAL_STATE_CODE(); 2668 2669 if (!tran) { 2670 tran = local_tran = tran_new(); 2671 } 2672 2673 ret = bdrv_do_refresh_perms(list, NULL, tran, errp); 2674 2675 if (local_tran) { 2676 tran_finalize(local_tran, ret); 2677 } 2678 2679 return ret; 2680 } 2681 2682 int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared, 2683 Error **errp) 2684 { 2685 Error *local_err = NULL; 2686 Transaction *tran = tran_new(); 2687 int ret; 2688 2689 GLOBAL_STATE_CODE(); 2690 2691 bdrv_child_set_perm(c, perm, shared, tran); 2692 2693 ret = bdrv_refresh_perms(c->bs, tran, &local_err); 2694 2695 tran_finalize(tran, ret); 2696 2697 if (ret < 0) { 2698 if ((perm & ~c->perm) || (c->shared_perm & ~shared)) { 2699 /* tighten permissions */ 2700 error_propagate(errp, local_err); 2701 } else { 2702 /* 2703 * Our caller may intend to only loosen restrictions and 2704 * does not expect this function to fail. Errors are not 2705 * fatal in such a case, so we can just hide them from our 2706 * caller. 2707 */ 2708 error_free(local_err); 2709 ret = 0; 2710 } 2711 } 2712 2713 return ret; 2714 } 2715 2716 int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp) 2717 { 2718 uint64_t parent_perms, parent_shared; 2719 uint64_t perms, shared; 2720 2721 GLOBAL_STATE_CODE(); 2722 2723 bdrv_get_cumulative_perm(bs, &parent_perms, &parent_shared); 2724 bdrv_child_perm(bs, c->bs, c, c->role, NULL, 2725 parent_perms, parent_shared, &perms, &shared); 2726 2727 return bdrv_child_try_set_perm(c, perms, shared, errp); 2728 } 2729 2730 /* 2731 * Default implementation for .bdrv_child_perm() for block filters: 2732 * Forward CONSISTENT_READ, WRITE, WRITE_UNCHANGED, and RESIZE to the 2733 * filtered child. 2734 */ 2735 static void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c, 2736 BdrvChildRole role, 2737 BlockReopenQueue *reopen_queue, 2738 uint64_t perm, uint64_t shared, 2739 uint64_t *nperm, uint64_t *nshared) 2740 { 2741 GLOBAL_STATE_CODE(); 2742 *nperm = perm & DEFAULT_PERM_PASSTHROUGH; 2743 *nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED; 2744 } 2745 2746 static void bdrv_default_perms_for_cow(BlockDriverState *bs, BdrvChild *c, 2747 BdrvChildRole role, 2748 BlockReopenQueue *reopen_queue, 2749 uint64_t perm, uint64_t shared, 2750 uint64_t *nperm, uint64_t *nshared) 2751 { 2752 assert(role & BDRV_CHILD_COW); 2753 GLOBAL_STATE_CODE(); 2754 2755 /* 2756 * We want consistent read from backing files if the parent needs it. 2757 * No other operations are performed on backing files. 2758 */ 2759 perm &= BLK_PERM_CONSISTENT_READ; 2760 2761 /* 2762 * If the parent can deal with changing data, we're okay with a 2763 * writable and resizable backing file. 2764 * TODO Require !(perm & BLK_PERM_CONSISTENT_READ), too? 2765 */ 2766 if (shared & BLK_PERM_WRITE) { 2767 shared = BLK_PERM_WRITE | BLK_PERM_RESIZE; 2768 } else { 2769 shared = 0; 2770 } 2771 2772 shared |= BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED; 2773 2774 if (bs->open_flags & BDRV_O_INACTIVE) { 2775 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE; 2776 } 2777 2778 *nperm = perm; 2779 *nshared = shared; 2780 } 2781 2782 static void bdrv_default_perms_for_storage(BlockDriverState *bs, BdrvChild *c, 2783 BdrvChildRole role, 2784 BlockReopenQueue *reopen_queue, 2785 uint64_t perm, uint64_t shared, 2786 uint64_t *nperm, uint64_t *nshared) 2787 { 2788 int flags; 2789 2790 GLOBAL_STATE_CODE(); 2791 assert(role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)); 2792 2793 flags = bdrv_reopen_get_flags(reopen_queue, bs); 2794 2795 /* 2796 * Apart from the modifications below, the same permissions are 2797 * forwarded and left alone as for filters 2798 */ 2799 bdrv_filter_default_perms(bs, c, role, reopen_queue, 2800 perm, shared, &perm, &shared); 2801 2802 if (role & BDRV_CHILD_METADATA) { 2803 /* Format drivers may touch metadata even if the guest doesn't write */ 2804 if (bdrv_is_writable_after_reopen(bs, reopen_queue)) { 2805 perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE; 2806 } 2807 2808 /* 2809 * bs->file always needs to be consistent because of the 2810 * metadata. We can never allow other users to resize or write 2811 * to it. 2812 */ 2813 if (!(flags & BDRV_O_NO_IO)) { 2814 perm |= BLK_PERM_CONSISTENT_READ; 2815 } 2816 shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE); 2817 } 2818 2819 if (role & BDRV_CHILD_DATA) { 2820 /* 2821 * Technically, everything in this block is a subset of the 2822 * BDRV_CHILD_METADATA path taken above, and so this could 2823 * be an "else if" branch. However, that is not obvious, and 2824 * this function is not performance critical, therefore we let 2825 * this be an independent "if". 2826 */ 2827 2828 /* 2829 * We cannot allow other users to resize the file because the 2830 * format driver might have some assumptions about the size 2831 * (e.g. because it is stored in metadata, or because the file 2832 * is split into fixed-size data files). 2833 */ 2834 shared &= ~BLK_PERM_RESIZE; 2835 2836 /* 2837 * WRITE_UNCHANGED often cannot be performed as such on the 2838 * data file. For example, the qcow2 driver may still need to 2839 * write copied clusters on copy-on-read. 2840 */ 2841 if (perm & BLK_PERM_WRITE_UNCHANGED) { 2842 perm |= BLK_PERM_WRITE; 2843 } 2844 2845 /* 2846 * If the data file is written to, the format driver may 2847 * expect to be able to resize it by writing beyond the EOF. 2848 */ 2849 if (perm & BLK_PERM_WRITE) { 2850 perm |= BLK_PERM_RESIZE; 2851 } 2852 } 2853 2854 if (bs->open_flags & BDRV_O_INACTIVE) { 2855 shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE; 2856 } 2857 2858 *nperm = perm; 2859 *nshared = shared; 2860 } 2861 2862 void bdrv_default_perms(BlockDriverState *bs, BdrvChild *c, 2863 BdrvChildRole role, BlockReopenQueue *reopen_queue, 2864 uint64_t perm, uint64_t shared, 2865 uint64_t *nperm, uint64_t *nshared) 2866 { 2867 GLOBAL_STATE_CODE(); 2868 if (role & BDRV_CHILD_FILTERED) { 2869 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA | 2870 BDRV_CHILD_COW))); 2871 bdrv_filter_default_perms(bs, c, role, reopen_queue, 2872 perm, shared, nperm, nshared); 2873 } else if (role & BDRV_CHILD_COW) { 2874 assert(!(role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA))); 2875 bdrv_default_perms_for_cow(bs, c, role, reopen_queue, 2876 perm, shared, nperm, nshared); 2877 } else if (role & (BDRV_CHILD_METADATA | BDRV_CHILD_DATA)) { 2878 bdrv_default_perms_for_storage(bs, c, role, reopen_queue, 2879 perm, shared, nperm, nshared); 2880 } else { 2881 g_assert_not_reached(); 2882 } 2883 } 2884 2885 uint64_t bdrv_qapi_perm_to_blk_perm(BlockPermission qapi_perm) 2886 { 2887 static const uint64_t permissions[] = { 2888 [BLOCK_PERMISSION_CONSISTENT_READ] = BLK_PERM_CONSISTENT_READ, 2889 [BLOCK_PERMISSION_WRITE] = BLK_PERM_WRITE, 2890 [BLOCK_PERMISSION_WRITE_UNCHANGED] = BLK_PERM_WRITE_UNCHANGED, 2891 [BLOCK_PERMISSION_RESIZE] = BLK_PERM_RESIZE, 2892 }; 2893 2894 QEMU_BUILD_BUG_ON(ARRAY_SIZE(permissions) != BLOCK_PERMISSION__MAX); 2895 QEMU_BUILD_BUG_ON(1UL << ARRAY_SIZE(permissions) != BLK_PERM_ALL + 1); 2896 2897 assert(qapi_perm < BLOCK_PERMISSION__MAX); 2898 2899 return permissions[qapi_perm]; 2900 } 2901 2902 /* 2903 * Replaces the node that a BdrvChild points to without updating permissions. 2904 * 2905 * If @new_bs is non-NULL, the parent of @child must already be drained through 2906 * @child and the caller must hold the AioContext lock for @new_bs. 2907 */ 2908 static void GRAPH_WRLOCK 2909 bdrv_replace_child_noperm(BdrvChild *child, BlockDriverState *new_bs) 2910 { 2911 BlockDriverState *old_bs = child->bs; 2912 int new_bs_quiesce_counter; 2913 2914 assert(!child->frozen); 2915 2916 /* 2917 * If we want to change the BdrvChild to point to a drained node as its new 2918 * child->bs, we need to make sure that its new parent is drained, too. In 2919 * other words, either child->quiesce_parent must already be true or we must 2920 * be able to set it and keep the parent's quiesce_counter consistent with 2921 * that, but without polling or starting new requests (this function 2922 * guarantees that it doesn't poll, and starting new requests would be 2923 * against the invariants of drain sections). 2924 * 2925 * To keep things simple, we pick the first option (child->quiesce_parent 2926 * must already be true). We also generalise the rule a bit to make it 2927 * easier to verify in callers and more likely to be covered in test cases: 2928 * The parent must be quiesced through this child even if new_bs isn't 2929 * currently drained. 2930 * 2931 * The only exception is for callers that always pass new_bs == NULL. In 2932 * this case, we obviously never need to consider the case of a drained 2933 * new_bs, so we can keep the callers simpler by allowing them not to drain 2934 * the parent. 2935 */ 2936 assert(!new_bs || child->quiesced_parent); 2937 assert(old_bs != new_bs); 2938 GLOBAL_STATE_CODE(); 2939 2940 if (old_bs && new_bs) { 2941 assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs)); 2942 } 2943 2944 if (old_bs) { 2945 if (child->klass->detach) { 2946 child->klass->detach(child); 2947 } 2948 QLIST_REMOVE(child, next_parent); 2949 } 2950 2951 child->bs = new_bs; 2952 2953 if (new_bs) { 2954 QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent); 2955 if (child->klass->attach) { 2956 child->klass->attach(child); 2957 } 2958 } 2959 2960 /* 2961 * If the parent was drained through this BdrvChild previously, but new_bs 2962 * is not drained, allow requests to come in only after the new node has 2963 * been attached. 2964 */ 2965 new_bs_quiesce_counter = (new_bs ? new_bs->quiesce_counter : 0); 2966 if (!new_bs_quiesce_counter && child->quiesced_parent) { 2967 bdrv_parent_drained_end_single(child); 2968 } 2969 } 2970 2971 /** 2972 * Free the given @child. 2973 * 2974 * The child must be empty (i.e. `child->bs == NULL`) and it must be 2975 * unused (i.e. not in a children list). 2976 */ 2977 static void bdrv_child_free(BdrvChild *child) 2978 { 2979 assert(!child->bs); 2980 GLOBAL_STATE_CODE(); 2981 GRAPH_RDLOCK_GUARD_MAINLOOP(); 2982 2983 assert(!child->next.le_prev); /* not in children list */ 2984 2985 g_free(child->name); 2986 g_free(child); 2987 } 2988 2989 typedef struct BdrvAttachChildCommonState { 2990 BdrvChild *child; 2991 AioContext *old_parent_ctx; 2992 AioContext *old_child_ctx; 2993 } BdrvAttachChildCommonState; 2994 2995 static void GRAPH_WRLOCK bdrv_attach_child_common_abort(void *opaque) 2996 { 2997 BdrvAttachChildCommonState *s = opaque; 2998 BlockDriverState *bs = s->child->bs; 2999 3000 GLOBAL_STATE_CODE(); 3001 assert_bdrv_graph_writable(); 3002 3003 bdrv_replace_child_noperm(s->child, NULL); 3004 3005 if (bdrv_get_aio_context(bs) != s->old_child_ctx) { 3006 bdrv_try_change_aio_context(bs, s->old_child_ctx, NULL, &error_abort); 3007 } 3008 3009 if (bdrv_child_get_parent_aio_context(s->child) != s->old_parent_ctx) { 3010 Transaction *tran; 3011 GHashTable *visited; 3012 bool ret; 3013 3014 tran = tran_new(); 3015 3016 /* No need to visit `child`, because it has been detached already */ 3017 visited = g_hash_table_new(NULL, NULL); 3018 ret = s->child->klass->change_aio_ctx(s->child, s->old_parent_ctx, 3019 visited, tran, &error_abort); 3020 g_hash_table_destroy(visited); 3021 3022 /* transaction is supposed to always succeed */ 3023 assert(ret == true); 3024 tran_commit(tran); 3025 } 3026 3027 bdrv_schedule_unref(bs); 3028 bdrv_child_free(s->child); 3029 } 3030 3031 static TransactionActionDrv bdrv_attach_child_common_drv = { 3032 .abort = bdrv_attach_child_common_abort, 3033 .clean = g_free, 3034 }; 3035 3036 /* 3037 * Common part of attaching bdrv child to bs or to blk or to job 3038 * 3039 * Function doesn't update permissions, caller is responsible for this. 3040 * 3041 * After calling this function, the transaction @tran may only be completed 3042 * while holding a writer lock for the graph. 3043 * 3044 * Returns new created child. 3045 * 3046 * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and 3047 * @child_bs can move to a different AioContext in this function. Callers must 3048 * make sure that their AioContext locking is still correct after this. 3049 */ 3050 static BdrvChild * GRAPH_WRLOCK 3051 bdrv_attach_child_common(BlockDriverState *child_bs, 3052 const char *child_name, 3053 const BdrvChildClass *child_class, 3054 BdrvChildRole child_role, 3055 uint64_t perm, uint64_t shared_perm, 3056 void *opaque, 3057 Transaction *tran, Error **errp) 3058 { 3059 BdrvChild *new_child; 3060 AioContext *parent_ctx, *new_child_ctx; 3061 AioContext *child_ctx = bdrv_get_aio_context(child_bs); 3062 3063 assert(child_class->get_parent_desc); 3064 GLOBAL_STATE_CODE(); 3065 3066 new_child = g_new(BdrvChild, 1); 3067 *new_child = (BdrvChild) { 3068 .bs = NULL, 3069 .name = g_strdup(child_name), 3070 .klass = child_class, 3071 .role = child_role, 3072 .perm = perm, 3073 .shared_perm = shared_perm, 3074 .opaque = opaque, 3075 }; 3076 3077 /* 3078 * If the AioContexts don't match, first try to move the subtree of 3079 * child_bs into the AioContext of the new parent. If this doesn't work, 3080 * try moving the parent into the AioContext of child_bs instead. 3081 */ 3082 parent_ctx = bdrv_child_get_parent_aio_context(new_child); 3083 if (child_ctx != parent_ctx) { 3084 Error *local_err = NULL; 3085 int ret = bdrv_try_change_aio_context(child_bs, parent_ctx, NULL, 3086 &local_err); 3087 3088 if (ret < 0 && child_class->change_aio_ctx) { 3089 Transaction *aio_ctx_tran = tran_new(); 3090 GHashTable *visited = g_hash_table_new(NULL, NULL); 3091 bool ret_child; 3092 3093 g_hash_table_add(visited, new_child); 3094 ret_child = child_class->change_aio_ctx(new_child, child_ctx, 3095 visited, aio_ctx_tran, 3096 NULL); 3097 if (ret_child == true) { 3098 error_free(local_err); 3099 ret = 0; 3100 } 3101 tran_finalize(aio_ctx_tran, ret_child == true ? 0 : -1); 3102 g_hash_table_destroy(visited); 3103 } 3104 3105 if (ret < 0) { 3106 error_propagate(errp, local_err); 3107 bdrv_child_free(new_child); 3108 return NULL; 3109 } 3110 } 3111 3112 new_child_ctx = bdrv_get_aio_context(child_bs); 3113 if (new_child_ctx != child_ctx) { 3114 aio_context_release(child_ctx); 3115 aio_context_acquire(new_child_ctx); 3116 } 3117 3118 bdrv_ref(child_bs); 3119 /* 3120 * Let every new BdrvChild start with a drained parent. Inserting the child 3121 * in the graph with bdrv_replace_child_noperm() will undrain it if 3122 * @child_bs is not drained. 3123 * 3124 * The child was only just created and is not yet visible in global state 3125 * until bdrv_replace_child_noperm() inserts it into the graph, so nobody 3126 * could have sent requests and polling is not necessary. 3127 * 3128 * Note that this means that the parent isn't fully drained yet, we only 3129 * stop new requests from coming in. This is fine, we don't care about the 3130 * old requests here, they are not for this child. If another place enters a 3131 * drain section for the same parent, but wants it to be fully quiesced, it 3132 * will not run most of the the code in .drained_begin() again (which is not 3133 * a problem, we already did this), but it will still poll until the parent 3134 * is fully quiesced, so it will not be negatively affected either. 3135 */ 3136 bdrv_parent_drained_begin_single(new_child); 3137 bdrv_replace_child_noperm(new_child, child_bs); 3138 3139 BdrvAttachChildCommonState *s = g_new(BdrvAttachChildCommonState, 1); 3140 *s = (BdrvAttachChildCommonState) { 3141 .child = new_child, 3142 .old_parent_ctx = parent_ctx, 3143 .old_child_ctx = child_ctx, 3144 }; 3145 tran_add(tran, &bdrv_attach_child_common_drv, s); 3146 3147 if (new_child_ctx != child_ctx) { 3148 aio_context_release(new_child_ctx); 3149 aio_context_acquire(child_ctx); 3150 } 3151 3152 return new_child; 3153 } 3154 3155 /* 3156 * Function doesn't update permissions, caller is responsible for this. 3157 * 3158 * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and 3159 * @child_bs can move to a different AioContext in this function. Callers must 3160 * make sure that their AioContext locking is still correct after this. 3161 * 3162 * After calling this function, the transaction @tran may only be completed 3163 * while holding a writer lock for the graph. 3164 */ 3165 static BdrvChild * GRAPH_WRLOCK 3166 bdrv_attach_child_noperm(BlockDriverState *parent_bs, 3167 BlockDriverState *child_bs, 3168 const char *child_name, 3169 const BdrvChildClass *child_class, 3170 BdrvChildRole child_role, 3171 Transaction *tran, 3172 Error **errp) 3173 { 3174 uint64_t perm, shared_perm; 3175 3176 assert(parent_bs->drv); 3177 GLOBAL_STATE_CODE(); 3178 3179 if (bdrv_recurse_has_child(child_bs, parent_bs)) { 3180 error_setg(errp, "Making '%s' a %s child of '%s' would create a cycle", 3181 child_bs->node_name, child_name, parent_bs->node_name); 3182 return NULL; 3183 } 3184 3185 bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm); 3186 bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL, 3187 perm, shared_perm, &perm, &shared_perm); 3188 3189 return bdrv_attach_child_common(child_bs, child_name, child_class, 3190 child_role, perm, shared_perm, parent_bs, 3191 tran, errp); 3192 } 3193 3194 /* 3195 * This function steals the reference to child_bs from the caller. 3196 * That reference is later dropped by bdrv_root_unref_child(). 3197 * 3198 * On failure NULL is returned, errp is set and the reference to 3199 * child_bs is also dropped. 3200 * 3201 * The caller must hold the AioContext lock @child_bs, but not that of @ctx 3202 * (unless @child_bs is already in @ctx). 3203 */ 3204 BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs, 3205 const char *child_name, 3206 const BdrvChildClass *child_class, 3207 BdrvChildRole child_role, 3208 uint64_t perm, uint64_t shared_perm, 3209 void *opaque, Error **errp) 3210 { 3211 int ret; 3212 BdrvChild *child; 3213 Transaction *tran = tran_new(); 3214 3215 GLOBAL_STATE_CODE(); 3216 3217 child = bdrv_attach_child_common(child_bs, child_name, child_class, 3218 child_role, perm, shared_perm, opaque, 3219 tran, errp); 3220 if (!child) { 3221 ret = -EINVAL; 3222 goto out; 3223 } 3224 3225 ret = bdrv_refresh_perms(child_bs, tran, errp); 3226 3227 out: 3228 tran_finalize(tran, ret); 3229 3230 bdrv_schedule_unref(child_bs); 3231 3232 return ret < 0 ? NULL : child; 3233 } 3234 3235 /* 3236 * This function transfers the reference to child_bs from the caller 3237 * to parent_bs. That reference is later dropped by parent_bs on 3238 * bdrv_close() or if someone calls bdrv_unref_child(). 3239 * 3240 * On failure NULL is returned, errp is set and the reference to 3241 * child_bs is also dropped. 3242 * 3243 * If @parent_bs and @child_bs are in different AioContexts, the caller must 3244 * hold the AioContext lock for @child_bs, but not for @parent_bs. 3245 */ 3246 BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, 3247 BlockDriverState *child_bs, 3248 const char *child_name, 3249 const BdrvChildClass *child_class, 3250 BdrvChildRole child_role, 3251 Error **errp) 3252 { 3253 int ret; 3254 BdrvChild *child; 3255 Transaction *tran = tran_new(); 3256 3257 GLOBAL_STATE_CODE(); 3258 3259 child = bdrv_attach_child_noperm(parent_bs, child_bs, child_name, 3260 child_class, child_role, tran, errp); 3261 if (!child) { 3262 ret = -EINVAL; 3263 goto out; 3264 } 3265 3266 ret = bdrv_refresh_perms(parent_bs, tran, errp); 3267 if (ret < 0) { 3268 goto out; 3269 } 3270 3271 out: 3272 tran_finalize(tran, ret); 3273 3274 bdrv_schedule_unref(child_bs); 3275 3276 return ret < 0 ? NULL : child; 3277 } 3278 3279 /* Callers must ensure that child->frozen is false. */ 3280 void bdrv_root_unref_child(BdrvChild *child) 3281 { 3282 BlockDriverState *child_bs = child->bs; 3283 3284 GLOBAL_STATE_CODE(); 3285 bdrv_replace_child_noperm(child, NULL); 3286 bdrv_child_free(child); 3287 3288 if (child_bs) { 3289 /* 3290 * Update permissions for old node. We're just taking a parent away, so 3291 * we're loosening restrictions. Errors of permission update are not 3292 * fatal in this case, ignore them. 3293 */ 3294 bdrv_refresh_perms(child_bs, NULL, NULL); 3295 3296 /* 3297 * When the parent requiring a non-default AioContext is removed, the 3298 * node moves back to the main AioContext 3299 */ 3300 bdrv_try_change_aio_context(child_bs, qemu_get_aio_context(), NULL, 3301 NULL); 3302 } 3303 3304 bdrv_schedule_unref(child_bs); 3305 } 3306 3307 typedef struct BdrvSetInheritsFrom { 3308 BlockDriverState *bs; 3309 BlockDriverState *old_inherits_from; 3310 } BdrvSetInheritsFrom; 3311 3312 static void bdrv_set_inherits_from_abort(void *opaque) 3313 { 3314 BdrvSetInheritsFrom *s = opaque; 3315 3316 s->bs->inherits_from = s->old_inherits_from; 3317 } 3318 3319 static TransactionActionDrv bdrv_set_inherits_from_drv = { 3320 .abort = bdrv_set_inherits_from_abort, 3321 .clean = g_free, 3322 }; 3323 3324 /* @tran is allowed to be NULL. In this case no rollback is possible */ 3325 static void bdrv_set_inherits_from(BlockDriverState *bs, 3326 BlockDriverState *new_inherits_from, 3327 Transaction *tran) 3328 { 3329 if (tran) { 3330 BdrvSetInheritsFrom *s = g_new(BdrvSetInheritsFrom, 1); 3331 3332 *s = (BdrvSetInheritsFrom) { 3333 .bs = bs, 3334 .old_inherits_from = bs->inherits_from, 3335 }; 3336 3337 tran_add(tran, &bdrv_set_inherits_from_drv, s); 3338 } 3339 3340 bs->inherits_from = new_inherits_from; 3341 } 3342 3343 /** 3344 * Clear all inherits_from pointers from children and grandchildren of 3345 * @root that point to @root, where necessary. 3346 * @tran is allowed to be NULL. In this case no rollback is possible 3347 */ 3348 static void GRAPH_WRLOCK 3349 bdrv_unset_inherits_from(BlockDriverState *root, BdrvChild *child, 3350 Transaction *tran) 3351 { 3352 BdrvChild *c; 3353 3354 if (child->bs->inherits_from == root) { 3355 /* 3356 * Remove inherits_from only when the last reference between root and 3357 * child->bs goes away. 3358 */ 3359 QLIST_FOREACH(c, &root->children, next) { 3360 if (c != child && c->bs == child->bs) { 3361 break; 3362 } 3363 } 3364 if (c == NULL) { 3365 bdrv_set_inherits_from(child->bs, NULL, tran); 3366 } 3367 } 3368 3369 QLIST_FOREACH(c, &child->bs->children, next) { 3370 bdrv_unset_inherits_from(root, c, tran); 3371 } 3372 } 3373 3374 /* Callers must ensure that child->frozen is false. */ 3375 void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child) 3376 { 3377 GLOBAL_STATE_CODE(); 3378 if (child == NULL) { 3379 return; 3380 } 3381 3382 bdrv_unset_inherits_from(parent, child, NULL); 3383 bdrv_root_unref_child(child); 3384 } 3385 3386 3387 static void GRAPH_RDLOCK 3388 bdrv_parent_cb_change_media(BlockDriverState *bs, bool load) 3389 { 3390 BdrvChild *c; 3391 GLOBAL_STATE_CODE(); 3392 QLIST_FOREACH(c, &bs->parents, next_parent) { 3393 if (c->klass->change_media) { 3394 c->klass->change_media(c, load); 3395 } 3396 } 3397 } 3398 3399 /* Return true if you can reach parent going through child->inherits_from 3400 * recursively. If parent or child are NULL, return false */ 3401 static bool bdrv_inherits_from_recursive(BlockDriverState *child, 3402 BlockDriverState *parent) 3403 { 3404 while (child && child != parent) { 3405 child = child->inherits_from; 3406 } 3407 3408 return child != NULL; 3409 } 3410 3411 /* 3412 * Return the BdrvChildRole for @bs's backing child. bs->backing is 3413 * mostly used for COW backing children (role = COW), but also for 3414 * filtered children (role = FILTERED | PRIMARY). 3415 */ 3416 static BdrvChildRole bdrv_backing_role(BlockDriverState *bs) 3417 { 3418 if (bs->drv && bs->drv->is_filter) { 3419 return BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY; 3420 } else { 3421 return BDRV_CHILD_COW; 3422 } 3423 } 3424 3425 /* 3426 * Sets the bs->backing or bs->file link of a BDS. A new reference is created; 3427 * callers which don't need their own reference any more must call bdrv_unref(). 3428 * 3429 * If the respective child is already present (i.e. we're detaching a node), 3430 * that child node must be drained. 3431 * 3432 * Function doesn't update permissions, caller is responsible for this. 3433 * 3434 * The caller must hold the AioContext lock for @child_bs. Both @parent_bs and 3435 * @child_bs can move to a different AioContext in this function. Callers must 3436 * make sure that their AioContext locking is still correct after this. 3437 * 3438 * After calling this function, the transaction @tran may only be completed 3439 * while holding a writer lock for the graph. 3440 */ 3441 static int GRAPH_WRLOCK 3442 bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs, 3443 BlockDriverState *child_bs, 3444 bool is_backing, 3445 Transaction *tran, Error **errp) 3446 { 3447 bool update_inherits_from = 3448 bdrv_inherits_from_recursive(child_bs, parent_bs); 3449 BdrvChild *child = is_backing ? parent_bs->backing : parent_bs->file; 3450 BdrvChildRole role; 3451 3452 GLOBAL_STATE_CODE(); 3453 3454 if (!parent_bs->drv) { 3455 /* 3456 * Node without drv is an object without a class :/. TODO: finally fix 3457 * qcow2 driver to never clear bs->drv and implement format corruption 3458 * handling in other way. 3459 */ 3460 error_setg(errp, "Node corrupted"); 3461 return -EINVAL; 3462 } 3463 3464 if (child && child->frozen) { 3465 error_setg(errp, "Cannot change frozen '%s' link from '%s' to '%s'", 3466 child->name, parent_bs->node_name, child->bs->node_name); 3467 return -EPERM; 3468 } 3469 3470 if (is_backing && !parent_bs->drv->is_filter && 3471 !parent_bs->drv->supports_backing) 3472 { 3473 error_setg(errp, "Driver '%s' of node '%s' does not support backing " 3474 "files", parent_bs->drv->format_name, parent_bs->node_name); 3475 return -EINVAL; 3476 } 3477 3478 if (parent_bs->drv->is_filter) { 3479 role = BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY; 3480 } else if (is_backing) { 3481 role = BDRV_CHILD_COW; 3482 } else { 3483 /* 3484 * We only can use same role as it is in existing child. We don't have 3485 * infrastructure to determine role of file child in generic way 3486 */ 3487 if (!child) { 3488 error_setg(errp, "Cannot set file child to format node without " 3489 "file child"); 3490 return -EINVAL; 3491 } 3492 role = child->role; 3493 } 3494 3495 if (child) { 3496 assert(child->bs->quiesce_counter); 3497 bdrv_unset_inherits_from(parent_bs, child, tran); 3498 bdrv_remove_child(child, tran); 3499 } 3500 3501 if (!child_bs) { 3502 goto out; 3503 } 3504 3505 child = bdrv_attach_child_noperm(parent_bs, child_bs, 3506 is_backing ? "backing" : "file", 3507 &child_of_bds, role, 3508 tran, errp); 3509 if (!child) { 3510 return -EINVAL; 3511 } 3512 3513 3514 /* 3515 * If inherits_from pointed recursively to bs then let's update it to 3516 * point directly to bs (else it will become NULL). 3517 */ 3518 if (update_inherits_from) { 3519 bdrv_set_inherits_from(child_bs, parent_bs, tran); 3520 } 3521 3522 out: 3523 bdrv_refresh_limits(parent_bs, tran, NULL); 3524 3525 return 0; 3526 } 3527 3528 /* 3529 * The caller must hold the AioContext lock for @backing_hd. Both @bs and 3530 * @backing_hd can move to a different AioContext in this function. Callers must 3531 * make sure that their AioContext locking is still correct after this. 3532 * 3533 * If a backing child is already present (i.e. we're detaching a node), that 3534 * child node must be drained. 3535 * 3536 * After calling this function, the transaction @tran may only be completed 3537 * while holding a writer lock for the graph. 3538 */ 3539 static int GRAPH_WRLOCK 3540 bdrv_set_backing_noperm(BlockDriverState *bs, 3541 BlockDriverState *backing_hd, 3542 Transaction *tran, Error **errp) 3543 { 3544 GLOBAL_STATE_CODE(); 3545 return bdrv_set_file_or_backing_noperm(bs, backing_hd, true, tran, errp); 3546 } 3547 3548 int bdrv_set_backing_hd_drained(BlockDriverState *bs, 3549 BlockDriverState *backing_hd, 3550 Error **errp) 3551 { 3552 int ret; 3553 Transaction *tran = tran_new(); 3554 3555 GLOBAL_STATE_CODE(); 3556 assert(bs->quiesce_counter > 0); 3557 if (bs->backing) { 3558 assert(bs->backing->bs->quiesce_counter > 0); 3559 } 3560 bdrv_graph_wrlock(backing_hd); 3561 3562 ret = bdrv_set_backing_noperm(bs, backing_hd, tran, errp); 3563 if (ret < 0) { 3564 goto out; 3565 } 3566 3567 ret = bdrv_refresh_perms(bs, tran, errp); 3568 out: 3569 tran_finalize(tran, ret); 3570 bdrv_graph_wrunlock(); 3571 return ret; 3572 } 3573 3574 int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd, 3575 Error **errp) 3576 { 3577 BlockDriverState *drain_bs = bs->backing ? bs->backing->bs : bs; 3578 int ret; 3579 GLOBAL_STATE_CODE(); 3580 3581 bdrv_ref(drain_bs); 3582 bdrv_drained_begin(drain_bs); 3583 ret = bdrv_set_backing_hd_drained(bs, backing_hd, errp); 3584 bdrv_drained_end(drain_bs); 3585 bdrv_unref(drain_bs); 3586 3587 return ret; 3588 } 3589 3590 /* 3591 * Opens the backing file for a BlockDriverState if not yet open 3592 * 3593 * bdref_key specifies the key for the image's BlockdevRef in the options QDict. 3594 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict 3595 * itself, all options starting with "${bdref_key}." are considered part of the 3596 * BlockdevRef. 3597 * 3598 * The caller must hold the main AioContext lock. 3599 * 3600 * TODO Can this be unified with bdrv_open_image()? 3601 */ 3602 int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options, 3603 const char *bdref_key, Error **errp) 3604 { 3605 char *backing_filename = NULL; 3606 char *bdref_key_dot; 3607 const char *reference = NULL; 3608 int ret = 0; 3609 bool implicit_backing = false; 3610 BlockDriverState *backing_hd; 3611 AioContext *backing_hd_ctx; 3612 QDict *options; 3613 QDict *tmp_parent_options = NULL; 3614 Error *local_err = NULL; 3615 3616 GLOBAL_STATE_CODE(); 3617 3618 if (bs->backing != NULL) { 3619 goto free_exit; 3620 } 3621 3622 /* NULL means an empty set of options */ 3623 if (parent_options == NULL) { 3624 tmp_parent_options = qdict_new(); 3625 parent_options = tmp_parent_options; 3626 } 3627 3628 bs->open_flags &= ~BDRV_O_NO_BACKING; 3629 3630 bdref_key_dot = g_strdup_printf("%s.", bdref_key); 3631 qdict_extract_subqdict(parent_options, &options, bdref_key_dot); 3632 g_free(bdref_key_dot); 3633 3634 /* 3635 * Caution: while qdict_get_try_str() is fine, getting non-string 3636 * types would require more care. When @parent_options come from 3637 * -blockdev or blockdev_add, its members are typed according to 3638 * the QAPI schema, but when they come from -drive, they're all 3639 * QString. 3640 */ 3641 reference = qdict_get_try_str(parent_options, bdref_key); 3642 if (reference || qdict_haskey(options, "file.filename")) { 3643 /* keep backing_filename NULL */ 3644 } else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) { 3645 qobject_unref(options); 3646 goto free_exit; 3647 } else { 3648 if (qdict_size(options) == 0) { 3649 /* If the user specifies options that do not modify the 3650 * backing file's behavior, we might still consider it the 3651 * implicit backing file. But it's easier this way, and 3652 * just specifying some of the backing BDS's options is 3653 * only possible with -drive anyway (otherwise the QAPI 3654 * schema forces the user to specify everything). */ 3655 implicit_backing = !strcmp(bs->auto_backing_file, bs->backing_file); 3656 } 3657 3658 bdrv_graph_rdlock_main_loop(); 3659 backing_filename = bdrv_get_full_backing_filename(bs, &local_err); 3660 bdrv_graph_rdunlock_main_loop(); 3661 3662 if (local_err) { 3663 ret = -EINVAL; 3664 error_propagate(errp, local_err); 3665 qobject_unref(options); 3666 goto free_exit; 3667 } 3668 } 3669 3670 if (!bs->drv || !bs->drv->supports_backing) { 3671 ret = -EINVAL; 3672 error_setg(errp, "Driver doesn't support backing files"); 3673 qobject_unref(options); 3674 goto free_exit; 3675 } 3676 3677 if (!reference && 3678 bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) { 3679 qdict_put_str(options, "driver", bs->backing_format); 3680 } 3681 3682 backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs, 3683 &child_of_bds, bdrv_backing_role(bs), errp); 3684 if (!backing_hd) { 3685 bs->open_flags |= BDRV_O_NO_BACKING; 3686 error_prepend(errp, "Could not open backing file: "); 3687 ret = -EINVAL; 3688 goto free_exit; 3689 } 3690 3691 if (implicit_backing) { 3692 bdrv_graph_rdlock_main_loop(); 3693 bdrv_refresh_filename(backing_hd); 3694 bdrv_graph_rdunlock_main_loop(); 3695 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file), 3696 backing_hd->filename); 3697 } 3698 3699 /* Hook up the backing file link; drop our reference, bs owns the 3700 * backing_hd reference now */ 3701 backing_hd_ctx = bdrv_get_aio_context(backing_hd); 3702 aio_context_acquire(backing_hd_ctx); 3703 ret = bdrv_set_backing_hd(bs, backing_hd, errp); 3704 bdrv_unref(backing_hd); 3705 aio_context_release(backing_hd_ctx); 3706 3707 if (ret < 0) { 3708 goto free_exit; 3709 } 3710 3711 qdict_del(parent_options, bdref_key); 3712 3713 free_exit: 3714 g_free(backing_filename); 3715 qobject_unref(tmp_parent_options); 3716 return ret; 3717 } 3718 3719 static BlockDriverState * 3720 bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key, 3721 BlockDriverState *parent, const BdrvChildClass *child_class, 3722 BdrvChildRole child_role, bool allow_none, Error **errp) 3723 { 3724 BlockDriverState *bs = NULL; 3725 QDict *image_options; 3726 char *bdref_key_dot; 3727 const char *reference; 3728 3729 assert(child_class != NULL); 3730 3731 bdref_key_dot = g_strdup_printf("%s.", bdref_key); 3732 qdict_extract_subqdict(options, &image_options, bdref_key_dot); 3733 g_free(bdref_key_dot); 3734 3735 /* 3736 * Caution: while qdict_get_try_str() is fine, getting non-string 3737 * types would require more care. When @options come from 3738 * -blockdev or blockdev_add, its members are typed according to 3739 * the QAPI schema, but when they come from -drive, they're all 3740 * QString. 3741 */ 3742 reference = qdict_get_try_str(options, bdref_key); 3743 if (!filename && !reference && !qdict_size(image_options)) { 3744 if (!allow_none) { 3745 error_setg(errp, "A block device must be specified for \"%s\"", 3746 bdref_key); 3747 } 3748 qobject_unref(image_options); 3749 goto done; 3750 } 3751 3752 bs = bdrv_open_inherit(filename, reference, image_options, 0, 3753 parent, child_class, child_role, errp); 3754 if (!bs) { 3755 goto done; 3756 } 3757 3758 done: 3759 qdict_del(options, bdref_key); 3760 return bs; 3761 } 3762 3763 /* 3764 * Opens a disk image whose options are given as BlockdevRef in another block 3765 * device's options. 3766 * 3767 * If allow_none is true, no image will be opened if filename is false and no 3768 * BlockdevRef is given. NULL will be returned, but errp remains unset. 3769 * 3770 * bdrev_key specifies the key for the image's BlockdevRef in the options QDict. 3771 * That QDict has to be flattened; therefore, if the BlockdevRef is a QDict 3772 * itself, all options starting with "${bdref_key}." are considered part of the 3773 * BlockdevRef. 3774 * 3775 * The BlockdevRef will be removed from the options QDict. 3776 * 3777 * The caller must hold the lock of the main AioContext and no other AioContext. 3778 * @parent can move to a different AioContext in this function. Callers must 3779 * make sure that their AioContext locking is still correct after this. 3780 */ 3781 BdrvChild *bdrv_open_child(const char *filename, 3782 QDict *options, const char *bdref_key, 3783 BlockDriverState *parent, 3784 const BdrvChildClass *child_class, 3785 BdrvChildRole child_role, 3786 bool allow_none, Error **errp) 3787 { 3788 BlockDriverState *bs; 3789 BdrvChild *child; 3790 AioContext *ctx; 3791 3792 GLOBAL_STATE_CODE(); 3793 3794 bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_class, 3795 child_role, allow_none, errp); 3796 if (bs == NULL) { 3797 return NULL; 3798 } 3799 3800 bdrv_graph_wrlock(NULL); 3801 ctx = bdrv_get_aio_context(bs); 3802 aio_context_acquire(ctx); 3803 child = bdrv_attach_child(parent, bs, bdref_key, child_class, child_role, 3804 errp); 3805 aio_context_release(ctx); 3806 bdrv_graph_wrunlock(); 3807 3808 return child; 3809 } 3810 3811 /* 3812 * Wrapper on bdrv_open_child() for most popular case: open primary child of bs. 3813 * 3814 * The caller must hold the lock of the main AioContext and no other AioContext. 3815 * @parent can move to a different AioContext in this function. Callers must 3816 * make sure that their AioContext locking is still correct after this. 3817 */ 3818 int bdrv_open_file_child(const char *filename, 3819 QDict *options, const char *bdref_key, 3820 BlockDriverState *parent, Error **errp) 3821 { 3822 BdrvChildRole role; 3823 3824 /* commit_top and mirror_top don't use this function */ 3825 assert(!parent->drv->filtered_child_is_backing); 3826 role = parent->drv->is_filter ? 3827 (BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY) : BDRV_CHILD_IMAGE; 3828 3829 if (!bdrv_open_child(filename, options, bdref_key, parent, 3830 &child_of_bds, role, false, errp)) 3831 { 3832 return -EINVAL; 3833 } 3834 3835 return 0; 3836 } 3837 3838 /* 3839 * TODO Future callers may need to specify parent/child_class in order for 3840 * option inheritance to work. Existing callers use it for the root node. 3841 */ 3842 BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp) 3843 { 3844 BlockDriverState *bs = NULL; 3845 QObject *obj = NULL; 3846 QDict *qdict = NULL; 3847 const char *reference = NULL; 3848 Visitor *v = NULL; 3849 3850 GLOBAL_STATE_CODE(); 3851 3852 if (ref->type == QTYPE_QSTRING) { 3853 reference = ref->u.reference; 3854 } else { 3855 BlockdevOptions *options = &ref->u.definition; 3856 assert(ref->type == QTYPE_QDICT); 3857 3858 v = qobject_output_visitor_new(&obj); 3859 visit_type_BlockdevOptions(v, NULL, &options, &error_abort); 3860 visit_complete(v, &obj); 3861 3862 qdict = qobject_to(QDict, obj); 3863 qdict_flatten(qdict); 3864 3865 /* bdrv_open_inherit() defaults to the values in bdrv_flags (for 3866 * compatibility with other callers) rather than what we want as the 3867 * real defaults. Apply the defaults here instead. */ 3868 qdict_set_default_str(qdict, BDRV_OPT_CACHE_DIRECT, "off"); 3869 qdict_set_default_str(qdict, BDRV_OPT_CACHE_NO_FLUSH, "off"); 3870 qdict_set_default_str(qdict, BDRV_OPT_READ_ONLY, "off"); 3871 qdict_set_default_str(qdict, BDRV_OPT_AUTO_READ_ONLY, "off"); 3872 3873 } 3874 3875 bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, 0, errp); 3876 obj = NULL; 3877 qobject_unref(obj); 3878 visit_free(v); 3879 return bs; 3880 } 3881 3882 static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs, 3883 int flags, 3884 QDict *snapshot_options, 3885 Error **errp) 3886 { 3887 g_autofree char *tmp_filename = NULL; 3888 int64_t total_size; 3889 QemuOpts *opts = NULL; 3890 BlockDriverState *bs_snapshot = NULL; 3891 AioContext *ctx = bdrv_get_aio_context(bs); 3892 int ret; 3893 3894 GLOBAL_STATE_CODE(); 3895 3896 /* if snapshot, we create a temporary backing file and open it 3897 instead of opening 'filename' directly */ 3898 3899 /* Get the required size from the image */ 3900 aio_context_acquire(ctx); 3901 total_size = bdrv_getlength(bs); 3902 aio_context_release(ctx); 3903 3904 if (total_size < 0) { 3905 error_setg_errno(errp, -total_size, "Could not get image size"); 3906 goto out; 3907 } 3908 3909 /* Create the temporary image */ 3910 tmp_filename = create_tmp_file(errp); 3911 if (!tmp_filename) { 3912 goto out; 3913 } 3914 3915 opts = qemu_opts_create(bdrv_qcow2.create_opts, NULL, 0, 3916 &error_abort); 3917 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, total_size, &error_abort); 3918 ret = bdrv_create(&bdrv_qcow2, tmp_filename, opts, errp); 3919 qemu_opts_del(opts); 3920 if (ret < 0) { 3921 error_prepend(errp, "Could not create temporary overlay '%s': ", 3922 tmp_filename); 3923 goto out; 3924 } 3925 3926 /* Prepare options QDict for the temporary file */ 3927 qdict_put_str(snapshot_options, "file.driver", "file"); 3928 qdict_put_str(snapshot_options, "file.filename", tmp_filename); 3929 qdict_put_str(snapshot_options, "driver", "qcow2"); 3930 3931 bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp); 3932 snapshot_options = NULL; 3933 if (!bs_snapshot) { 3934 goto out; 3935 } 3936 3937 aio_context_acquire(ctx); 3938 ret = bdrv_append(bs_snapshot, bs, errp); 3939 aio_context_release(ctx); 3940 3941 if (ret < 0) { 3942 bs_snapshot = NULL; 3943 goto out; 3944 } 3945 3946 out: 3947 qobject_unref(snapshot_options); 3948 return bs_snapshot; 3949 } 3950 3951 /* 3952 * Opens a disk image (raw, qcow2, vmdk, ...) 3953 * 3954 * options is a QDict of options to pass to the block drivers, or NULL for an 3955 * empty set of options. The reference to the QDict belongs to the block layer 3956 * after the call (even on failure), so if the caller intends to reuse the 3957 * dictionary, it needs to use qobject_ref() before calling bdrv_open. 3958 * 3959 * If *pbs is NULL, a new BDS will be created with a pointer to it stored there. 3960 * If it is not NULL, the referenced BDS will be reused. 3961 * 3962 * The reference parameter may be used to specify an existing block device which 3963 * should be opened. If specified, neither options nor a filename may be given, 3964 * nor can an existing BDS be reused (that is, *pbs has to be NULL). 3965 * 3966 * The caller must always hold the main AioContext lock. 3967 */ 3968 static BlockDriverState * no_coroutine_fn 3969 bdrv_open_inherit(const char *filename, const char *reference, QDict *options, 3970 int flags, BlockDriverState *parent, 3971 const BdrvChildClass *child_class, BdrvChildRole child_role, 3972 Error **errp) 3973 { 3974 int ret; 3975 BlockBackend *file = NULL; 3976 BlockDriverState *bs; 3977 BlockDriver *drv = NULL; 3978 BdrvChild *child; 3979 const char *drvname; 3980 const char *backing; 3981 Error *local_err = NULL; 3982 QDict *snapshot_options = NULL; 3983 int snapshot_flags = 0; 3984 AioContext *ctx = qemu_get_aio_context(); 3985 3986 assert(!child_class || !flags); 3987 assert(!child_class == !parent); 3988 GLOBAL_STATE_CODE(); 3989 assert(!qemu_in_coroutine()); 3990 3991 /* TODO We'll eventually have to take a writer lock in this function */ 3992 GRAPH_RDLOCK_GUARD_MAINLOOP(); 3993 3994 if (reference) { 3995 bool options_non_empty = options ? qdict_size(options) : false; 3996 qobject_unref(options); 3997 3998 if (filename || options_non_empty) { 3999 error_setg(errp, "Cannot reference an existing block device with " 4000 "additional options or a new filename"); 4001 return NULL; 4002 } 4003 4004 bs = bdrv_lookup_bs(reference, reference, errp); 4005 if (!bs) { 4006 return NULL; 4007 } 4008 4009 bdrv_ref(bs); 4010 return bs; 4011 } 4012 4013 bs = bdrv_new(); 4014 4015 /* NULL means an empty set of options */ 4016 if (options == NULL) { 4017 options = qdict_new(); 4018 } 4019 4020 /* json: syntax counts as explicit options, as if in the QDict */ 4021 parse_json_protocol(options, &filename, &local_err); 4022 if (local_err) { 4023 goto fail; 4024 } 4025 4026 bs->explicit_options = qdict_clone_shallow(options); 4027 4028 if (child_class) { 4029 bool parent_is_format; 4030 4031 if (parent->drv) { 4032 parent_is_format = parent->drv->is_format; 4033 } else { 4034 /* 4035 * parent->drv is not set yet because this node is opened for 4036 * (potential) format probing. That means that @parent is going 4037 * to be a format node. 4038 */ 4039 parent_is_format = true; 4040 } 4041 4042 bs->inherits_from = parent; 4043 child_class->inherit_options(child_role, parent_is_format, 4044 &flags, options, 4045 parent->open_flags, parent->options); 4046 } 4047 4048 ret = bdrv_fill_options(&options, filename, &flags, &local_err); 4049 if (ret < 0) { 4050 goto fail; 4051 } 4052 4053 /* 4054 * Set the BDRV_O_RDWR and BDRV_O_ALLOW_RDWR flags. 4055 * Caution: getting a boolean member of @options requires care. 4056 * When @options come from -blockdev or blockdev_add, members are 4057 * typed according to the QAPI schema, but when they come from 4058 * -drive, they're all QString. 4059 */ 4060 if (g_strcmp0(qdict_get_try_str(options, BDRV_OPT_READ_ONLY), "on") && 4061 !qdict_get_try_bool(options, BDRV_OPT_READ_ONLY, false)) { 4062 flags |= (BDRV_O_RDWR | BDRV_O_ALLOW_RDWR); 4063 } else { 4064 flags &= ~BDRV_O_RDWR; 4065 } 4066 4067 if (flags & BDRV_O_SNAPSHOT) { 4068 snapshot_options = qdict_new(); 4069 bdrv_temp_snapshot_options(&snapshot_flags, snapshot_options, 4070 flags, options); 4071 /* Let bdrv_backing_options() override "read-only" */ 4072 qdict_del(options, BDRV_OPT_READ_ONLY); 4073 bdrv_inherited_options(BDRV_CHILD_COW, true, 4074 &flags, options, flags, options); 4075 } 4076 4077 bs->open_flags = flags; 4078 bs->options = options; 4079 options = qdict_clone_shallow(options); 4080 4081 /* Find the right image format driver */ 4082 /* See cautionary note on accessing @options above */ 4083 drvname = qdict_get_try_str(options, "driver"); 4084 if (drvname) { 4085 drv = bdrv_find_format(drvname); 4086 if (!drv) { 4087 error_setg(errp, "Unknown driver: '%s'", drvname); 4088 goto fail; 4089 } 4090 } 4091 4092 assert(drvname || !(flags & BDRV_O_PROTOCOL)); 4093 4094 /* See cautionary note on accessing @options above */ 4095 backing = qdict_get_try_str(options, "backing"); 4096 if (qobject_to(QNull, qdict_get(options, "backing")) != NULL || 4097 (backing && *backing == '\0')) 4098 { 4099 if (backing) { 4100 warn_report("Use of \"backing\": \"\" is deprecated; " 4101 "use \"backing\": null instead"); 4102 } 4103 flags |= BDRV_O_NO_BACKING; 4104 qdict_del(bs->explicit_options, "backing"); 4105 qdict_del(bs->options, "backing"); 4106 qdict_del(options, "backing"); 4107 } 4108 4109 /* Open image file without format layer. This BlockBackend is only used for 4110 * probing, the block drivers will do their own bdrv_open_child() for the 4111 * same BDS, which is why we put the node name back into options. */ 4112 if ((flags & BDRV_O_PROTOCOL) == 0) { 4113 BlockDriverState *file_bs; 4114 4115 file_bs = bdrv_open_child_bs(filename, options, "file", bs, 4116 &child_of_bds, BDRV_CHILD_IMAGE, 4117 true, &local_err); 4118 if (local_err) { 4119 goto fail; 4120 } 4121 if (file_bs != NULL) { 4122 /* Not requesting BLK_PERM_CONSISTENT_READ because we're only 4123 * looking at the header to guess the image format. This works even 4124 * in cases where a guest would not see a consistent state. */ 4125 ctx = bdrv_get_aio_context(file_bs); 4126 aio_context_acquire(ctx); 4127 file = blk_new(ctx, 0, BLK_PERM_ALL); 4128 blk_insert_bs(file, file_bs, &local_err); 4129 bdrv_unref(file_bs); 4130 aio_context_release(ctx); 4131 4132 if (local_err) { 4133 goto fail; 4134 } 4135 4136 qdict_put_str(options, "file", bdrv_get_node_name(file_bs)); 4137 } 4138 } 4139 4140 /* Image format probing */ 4141 bs->probed = !drv; 4142 if (!drv && file) { 4143 ret = find_image_format(file, filename, &drv, &local_err); 4144 if (ret < 0) { 4145 goto fail; 4146 } 4147 /* 4148 * This option update would logically belong in bdrv_fill_options(), 4149 * but we first need to open bs->file for the probing to work, while 4150 * opening bs->file already requires the (mostly) final set of options 4151 * so that cache mode etc. can be inherited. 4152 * 4153 * Adding the driver later is somewhat ugly, but it's not an option 4154 * that would ever be inherited, so it's correct. We just need to make 4155 * sure to update both bs->options (which has the full effective 4156 * options for bs) and options (which has file.* already removed). 4157 */ 4158 qdict_put_str(bs->options, "driver", drv->format_name); 4159 qdict_put_str(options, "driver", drv->format_name); 4160 } else if (!drv) { 4161 error_setg(errp, "Must specify either driver or file"); 4162 goto fail; 4163 } 4164 4165 /* BDRV_O_PROTOCOL must be set iff a protocol BDS is about to be created */ 4166 assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->bdrv_file_open); 4167 /* file must be NULL if a protocol BDS is about to be created 4168 * (the inverse results in an error message from bdrv_open_common()) */ 4169 assert(!(flags & BDRV_O_PROTOCOL) || !file); 4170 4171 /* Open the image */ 4172 ret = bdrv_open_common(bs, file, options, &local_err); 4173 if (ret < 0) { 4174 goto fail; 4175 } 4176 4177 /* The AioContext could have changed during bdrv_open_common() */ 4178 ctx = bdrv_get_aio_context(bs); 4179 4180 if (file) { 4181 aio_context_acquire(ctx); 4182 blk_unref(file); 4183 aio_context_release(ctx); 4184 file = NULL; 4185 } 4186 4187 /* If there is a backing file, use it */ 4188 if ((flags & BDRV_O_NO_BACKING) == 0) { 4189 ret = bdrv_open_backing_file(bs, options, "backing", &local_err); 4190 if (ret < 0) { 4191 goto close_and_fail; 4192 } 4193 } 4194 4195 /* Remove all children options and references 4196 * from bs->options and bs->explicit_options */ 4197 QLIST_FOREACH(child, &bs->children, next) { 4198 char *child_key_dot; 4199 child_key_dot = g_strdup_printf("%s.", child->name); 4200 qdict_extract_subqdict(bs->explicit_options, NULL, child_key_dot); 4201 qdict_extract_subqdict(bs->options, NULL, child_key_dot); 4202 qdict_del(bs->explicit_options, child->name); 4203 qdict_del(bs->options, child->name); 4204 g_free(child_key_dot); 4205 } 4206 4207 /* Check if any unknown options were used */ 4208 if (qdict_size(options) != 0) { 4209 const QDictEntry *entry = qdict_first(options); 4210 if (flags & BDRV_O_PROTOCOL) { 4211 error_setg(errp, "Block protocol '%s' doesn't support the option " 4212 "'%s'", drv->format_name, entry->key); 4213 } else { 4214 error_setg(errp, 4215 "Block format '%s' does not support the option '%s'", 4216 drv->format_name, entry->key); 4217 } 4218 4219 goto close_and_fail; 4220 } 4221 4222 bdrv_parent_cb_change_media(bs, true); 4223 4224 qobject_unref(options); 4225 options = NULL; 4226 4227 /* For snapshot=on, create a temporary qcow2 overlay. bs points to the 4228 * temporary snapshot afterwards. */ 4229 if (snapshot_flags) { 4230 BlockDriverState *snapshot_bs; 4231 snapshot_bs = bdrv_append_temp_snapshot(bs, snapshot_flags, 4232 snapshot_options, &local_err); 4233 snapshot_options = NULL; 4234 if (local_err) { 4235 goto close_and_fail; 4236 } 4237 /* We are not going to return bs but the overlay on top of it 4238 * (snapshot_bs); thus, we have to drop the strong reference to bs 4239 * (which we obtained by calling bdrv_new()). bs will not be deleted, 4240 * though, because the overlay still has a reference to it. */ 4241 aio_context_acquire(ctx); 4242 bdrv_unref(bs); 4243 aio_context_release(ctx); 4244 bs = snapshot_bs; 4245 } 4246 4247 return bs; 4248 4249 fail: 4250 aio_context_acquire(ctx); 4251 blk_unref(file); 4252 qobject_unref(snapshot_options); 4253 qobject_unref(bs->explicit_options); 4254 qobject_unref(bs->options); 4255 qobject_unref(options); 4256 bs->options = NULL; 4257 bs->explicit_options = NULL; 4258 bdrv_unref(bs); 4259 aio_context_release(ctx); 4260 error_propagate(errp, local_err); 4261 return NULL; 4262 4263 close_and_fail: 4264 aio_context_acquire(ctx); 4265 bdrv_unref(bs); 4266 aio_context_release(ctx); 4267 qobject_unref(snapshot_options); 4268 qobject_unref(options); 4269 error_propagate(errp, local_err); 4270 return NULL; 4271 } 4272 4273 /* The caller must always hold the main AioContext lock. */ 4274 BlockDriverState *bdrv_open(const char *filename, const char *reference, 4275 QDict *options, int flags, Error **errp) 4276 { 4277 GLOBAL_STATE_CODE(); 4278 4279 return bdrv_open_inherit(filename, reference, options, flags, NULL, 4280 NULL, 0, errp); 4281 } 4282 4283 /* Return true if the NULL-terminated @list contains @str */ 4284 static bool is_str_in_list(const char *str, const char *const *list) 4285 { 4286 if (str && list) { 4287 int i; 4288 for (i = 0; list[i] != NULL; i++) { 4289 if (!strcmp(str, list[i])) { 4290 return true; 4291 } 4292 } 4293 } 4294 return false; 4295 } 4296 4297 /* 4298 * Check that every option set in @bs->options is also set in 4299 * @new_opts. 4300 * 4301 * Options listed in the common_options list and in 4302 * @bs->drv->mutable_opts are skipped. 4303 * 4304 * Return 0 on success, otherwise return -EINVAL and set @errp. 4305 */ 4306 static int bdrv_reset_options_allowed(BlockDriverState *bs, 4307 const QDict *new_opts, Error **errp) 4308 { 4309 const QDictEntry *e; 4310 /* These options are common to all block drivers and are handled 4311 * in bdrv_reopen_prepare() so they can be left out of @new_opts */ 4312 const char *const common_options[] = { 4313 "node-name", "discard", "cache.direct", "cache.no-flush", 4314 "read-only", "auto-read-only", "detect-zeroes", NULL 4315 }; 4316 4317 for (e = qdict_first(bs->options); e; e = qdict_next(bs->options, e)) { 4318 if (!qdict_haskey(new_opts, e->key) && 4319 !is_str_in_list(e->key, common_options) && 4320 !is_str_in_list(e->key, bs->drv->mutable_opts)) { 4321 error_setg(errp, "Option '%s' cannot be reset " 4322 "to its default value", e->key); 4323 return -EINVAL; 4324 } 4325 } 4326 4327 return 0; 4328 } 4329 4330 /* 4331 * Returns true if @child can be reached recursively from @bs 4332 */ 4333 static bool GRAPH_RDLOCK 4334 bdrv_recurse_has_child(BlockDriverState *bs, BlockDriverState *child) 4335 { 4336 BdrvChild *c; 4337 4338 if (bs == child) { 4339 return true; 4340 } 4341 4342 QLIST_FOREACH(c, &bs->children, next) { 4343 if (bdrv_recurse_has_child(c->bs, child)) { 4344 return true; 4345 } 4346 } 4347 4348 return false; 4349 } 4350 4351 /* 4352 * Adds a BlockDriverState to a simple queue for an atomic, transactional 4353 * reopen of multiple devices. 4354 * 4355 * bs_queue can either be an existing BlockReopenQueue that has had QTAILQ_INIT 4356 * already performed, or alternatively may be NULL a new BlockReopenQueue will 4357 * be created and initialized. This newly created BlockReopenQueue should be 4358 * passed back in for subsequent calls that are intended to be of the same 4359 * atomic 'set'. 4360 * 4361 * bs is the BlockDriverState to add to the reopen queue. 4362 * 4363 * options contains the changed options for the associated bs 4364 * (the BlockReopenQueue takes ownership) 4365 * 4366 * flags contains the open flags for the associated bs 4367 * 4368 * returns a pointer to bs_queue, which is either the newly allocated 4369 * bs_queue, or the existing bs_queue being used. 4370 * 4371 * bs is drained here and undrained by bdrv_reopen_queue_free(). 4372 * 4373 * To be called with bs->aio_context locked. 4374 */ 4375 static BlockReopenQueue * GRAPH_RDLOCK 4376 bdrv_reopen_queue_child(BlockReopenQueue *bs_queue, BlockDriverState *bs, 4377 QDict *options, const BdrvChildClass *klass, 4378 BdrvChildRole role, bool parent_is_format, 4379 QDict *parent_options, int parent_flags, 4380 bool keep_old_opts) 4381 { 4382 assert(bs != NULL); 4383 4384 BlockReopenQueueEntry *bs_entry; 4385 BdrvChild *child; 4386 QDict *old_options, *explicit_options, *options_copy; 4387 int flags; 4388 QemuOpts *opts; 4389 4390 GLOBAL_STATE_CODE(); 4391 4392 /* 4393 * Strictly speaking, draining is illegal under GRAPH_RDLOCK. We know that 4394 * we've been called with bdrv_graph_rdlock_main_loop(), though, so it's ok 4395 * in practice. 4396 */ 4397 bdrv_drained_begin(bs); 4398 4399 if (bs_queue == NULL) { 4400 bs_queue = g_new0(BlockReopenQueue, 1); 4401 QTAILQ_INIT(bs_queue); 4402 } 4403 4404 if (!options) { 4405 options = qdict_new(); 4406 } 4407 4408 /* Check if this BlockDriverState is already in the queue */ 4409 QTAILQ_FOREACH(bs_entry, bs_queue, entry) { 4410 if (bs == bs_entry->state.bs) { 4411 break; 4412 } 4413 } 4414 4415 /* 4416 * Precedence of options: 4417 * 1. Explicitly passed in options (highest) 4418 * 2. Retained from explicitly set options of bs 4419 * 3. Inherited from parent node 4420 * 4. Retained from effective options of bs 4421 */ 4422 4423 /* Old explicitly set values (don't overwrite by inherited value) */ 4424 if (bs_entry || keep_old_opts) { 4425 old_options = qdict_clone_shallow(bs_entry ? 4426 bs_entry->state.explicit_options : 4427 bs->explicit_options); 4428 bdrv_join_options(bs, options, old_options); 4429 qobject_unref(old_options); 4430 } 4431 4432 explicit_options = qdict_clone_shallow(options); 4433 4434 /* Inherit from parent node */ 4435 if (parent_options) { 4436 flags = 0; 4437 klass->inherit_options(role, parent_is_format, &flags, options, 4438 parent_flags, parent_options); 4439 } else { 4440 flags = bdrv_get_flags(bs); 4441 } 4442 4443 if (keep_old_opts) { 4444 /* Old values are used for options that aren't set yet */ 4445 old_options = qdict_clone_shallow(bs->options); 4446 bdrv_join_options(bs, options, old_options); 4447 qobject_unref(old_options); 4448 } 4449 4450 /* We have the final set of options so let's update the flags */ 4451 options_copy = qdict_clone_shallow(options); 4452 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); 4453 qemu_opts_absorb_qdict(opts, options_copy, NULL); 4454 update_flags_from_options(&flags, opts); 4455 qemu_opts_del(opts); 4456 qobject_unref(options_copy); 4457 4458 /* bdrv_open_inherit() sets and clears some additional flags internally */ 4459 flags &= ~BDRV_O_PROTOCOL; 4460 if (flags & BDRV_O_RDWR) { 4461 flags |= BDRV_O_ALLOW_RDWR; 4462 } 4463 4464 if (!bs_entry) { 4465 bs_entry = g_new0(BlockReopenQueueEntry, 1); 4466 QTAILQ_INSERT_TAIL(bs_queue, bs_entry, entry); 4467 } else { 4468 qobject_unref(bs_entry->state.options); 4469 qobject_unref(bs_entry->state.explicit_options); 4470 } 4471 4472 bs_entry->state.bs = bs; 4473 bs_entry->state.options = options; 4474 bs_entry->state.explicit_options = explicit_options; 4475 bs_entry->state.flags = flags; 4476 4477 /* 4478 * If keep_old_opts is false then it means that unspecified 4479 * options must be reset to their original value. We don't allow 4480 * resetting 'backing' but we need to know if the option is 4481 * missing in order to decide if we have to return an error. 4482 */ 4483 if (!keep_old_opts) { 4484 bs_entry->state.backing_missing = 4485 !qdict_haskey(options, "backing") && 4486 !qdict_haskey(options, "backing.driver"); 4487 } 4488 4489 QLIST_FOREACH(child, &bs->children, next) { 4490 QDict *new_child_options = NULL; 4491 bool child_keep_old = keep_old_opts; 4492 4493 /* reopen can only change the options of block devices that were 4494 * implicitly created and inherited options. For other (referenced) 4495 * block devices, a syntax like "backing.foo" results in an error. */ 4496 if (child->bs->inherits_from != bs) { 4497 continue; 4498 } 4499 4500 /* Check if the options contain a child reference */ 4501 if (qdict_haskey(options, child->name)) { 4502 const char *childref = qdict_get_try_str(options, child->name); 4503 /* 4504 * The current child must not be reopened if the child 4505 * reference is null or points to a different node. 4506 */ 4507 if (g_strcmp0(childref, child->bs->node_name)) { 4508 continue; 4509 } 4510 /* 4511 * If the child reference points to the current child then 4512 * reopen it with its existing set of options (note that 4513 * it can still inherit new options from the parent). 4514 */ 4515 child_keep_old = true; 4516 } else { 4517 /* Extract child options ("child-name.*") */ 4518 char *child_key_dot = g_strdup_printf("%s.", child->name); 4519 qdict_extract_subqdict(explicit_options, NULL, child_key_dot); 4520 qdict_extract_subqdict(options, &new_child_options, child_key_dot); 4521 g_free(child_key_dot); 4522 } 4523 4524 bdrv_reopen_queue_child(bs_queue, child->bs, new_child_options, 4525 child->klass, child->role, bs->drv->is_format, 4526 options, flags, child_keep_old); 4527 } 4528 4529 return bs_queue; 4530 } 4531 4532 /* To be called with bs->aio_context locked */ 4533 BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue, 4534 BlockDriverState *bs, 4535 QDict *options, bool keep_old_opts) 4536 { 4537 GLOBAL_STATE_CODE(); 4538 GRAPH_RDLOCK_GUARD_MAINLOOP(); 4539 4540 return bdrv_reopen_queue_child(bs_queue, bs, options, NULL, 0, false, 4541 NULL, 0, keep_old_opts); 4542 } 4543 4544 void bdrv_reopen_queue_free(BlockReopenQueue *bs_queue) 4545 { 4546 GLOBAL_STATE_CODE(); 4547 if (bs_queue) { 4548 BlockReopenQueueEntry *bs_entry, *next; 4549 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) { 4550 AioContext *ctx = bdrv_get_aio_context(bs_entry->state.bs); 4551 4552 aio_context_acquire(ctx); 4553 bdrv_drained_end(bs_entry->state.bs); 4554 aio_context_release(ctx); 4555 4556 qobject_unref(bs_entry->state.explicit_options); 4557 qobject_unref(bs_entry->state.options); 4558 g_free(bs_entry); 4559 } 4560 g_free(bs_queue); 4561 } 4562 } 4563 4564 /* 4565 * Reopen multiple BlockDriverStates atomically & transactionally. 4566 * 4567 * The queue passed in (bs_queue) must have been built up previous 4568 * via bdrv_reopen_queue(). 4569 * 4570 * Reopens all BDS specified in the queue, with the appropriate 4571 * flags. All devices are prepared for reopen, and failure of any 4572 * device will cause all device changes to be abandoned, and intermediate 4573 * data cleaned up. 4574 * 4575 * If all devices prepare successfully, then the changes are committed 4576 * to all devices. 4577 * 4578 * All affected nodes must be drained between bdrv_reopen_queue() and 4579 * bdrv_reopen_multiple(). 4580 * 4581 * To be called from the main thread, with all other AioContexts unlocked. 4582 */ 4583 int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp) 4584 { 4585 int ret = -1; 4586 BlockReopenQueueEntry *bs_entry, *next; 4587 AioContext *ctx; 4588 Transaction *tran = tran_new(); 4589 g_autoptr(GSList) refresh_list = NULL; 4590 4591 assert(qemu_get_current_aio_context() == qemu_get_aio_context()); 4592 assert(bs_queue != NULL); 4593 GLOBAL_STATE_CODE(); 4594 4595 QTAILQ_FOREACH(bs_entry, bs_queue, entry) { 4596 ctx = bdrv_get_aio_context(bs_entry->state.bs); 4597 aio_context_acquire(ctx); 4598 ret = bdrv_flush(bs_entry->state.bs); 4599 aio_context_release(ctx); 4600 if (ret < 0) { 4601 error_setg_errno(errp, -ret, "Error flushing drive"); 4602 goto abort; 4603 } 4604 } 4605 4606 QTAILQ_FOREACH(bs_entry, bs_queue, entry) { 4607 assert(bs_entry->state.bs->quiesce_counter > 0); 4608 ctx = bdrv_get_aio_context(bs_entry->state.bs); 4609 aio_context_acquire(ctx); 4610 ret = bdrv_reopen_prepare(&bs_entry->state, bs_queue, tran, errp); 4611 aio_context_release(ctx); 4612 if (ret < 0) { 4613 goto abort; 4614 } 4615 bs_entry->prepared = true; 4616 } 4617 4618 QTAILQ_FOREACH(bs_entry, bs_queue, entry) { 4619 BDRVReopenState *state = &bs_entry->state; 4620 4621 refresh_list = g_slist_prepend(refresh_list, state->bs); 4622 if (state->old_backing_bs) { 4623 refresh_list = g_slist_prepend(refresh_list, state->old_backing_bs); 4624 } 4625 if (state->old_file_bs) { 4626 refresh_list = g_slist_prepend(refresh_list, state->old_file_bs); 4627 } 4628 } 4629 4630 /* 4631 * Note that file-posix driver rely on permission update done during reopen 4632 * (even if no permission changed), because it wants "new" permissions for 4633 * reconfiguring the fd and that's why it does it in raw_check_perm(), not 4634 * in raw_reopen_prepare() which is called with "old" permissions. 4635 */ 4636 bdrv_graph_rdlock_main_loop(); 4637 ret = bdrv_list_refresh_perms(refresh_list, bs_queue, tran, errp); 4638 bdrv_graph_rdunlock_main_loop(); 4639 4640 if (ret < 0) { 4641 goto abort; 4642 } 4643 4644 /* 4645 * If we reach this point, we have success and just need to apply the 4646 * changes. 4647 * 4648 * Reverse order is used to comfort qcow2 driver: on commit it need to write 4649 * IN_USE flag to the image, to mark bitmaps in the image as invalid. But 4650 * children are usually goes after parents in reopen-queue, so go from last 4651 * to first element. 4652 */ 4653 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) { 4654 ctx = bdrv_get_aio_context(bs_entry->state.bs); 4655 aio_context_acquire(ctx); 4656 bdrv_reopen_commit(&bs_entry->state); 4657 aio_context_release(ctx); 4658 } 4659 4660 bdrv_graph_wrlock(NULL); 4661 tran_commit(tran); 4662 bdrv_graph_wrunlock(); 4663 4664 QTAILQ_FOREACH_REVERSE(bs_entry, bs_queue, entry) { 4665 BlockDriverState *bs = bs_entry->state.bs; 4666 4667 if (bs->drv->bdrv_reopen_commit_post) { 4668 ctx = bdrv_get_aio_context(bs); 4669 aio_context_acquire(ctx); 4670 bs->drv->bdrv_reopen_commit_post(&bs_entry->state); 4671 aio_context_release(ctx); 4672 } 4673 } 4674 4675 ret = 0; 4676 goto cleanup; 4677 4678 abort: 4679 bdrv_graph_wrlock(NULL); 4680 tran_abort(tran); 4681 bdrv_graph_wrunlock(); 4682 4683 QTAILQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) { 4684 if (bs_entry->prepared) { 4685 ctx = bdrv_get_aio_context(bs_entry->state.bs); 4686 aio_context_acquire(ctx); 4687 bdrv_reopen_abort(&bs_entry->state); 4688 aio_context_release(ctx); 4689 } 4690 } 4691 4692 cleanup: 4693 bdrv_reopen_queue_free(bs_queue); 4694 4695 return ret; 4696 } 4697 4698 int bdrv_reopen(BlockDriverState *bs, QDict *opts, bool keep_old_opts, 4699 Error **errp) 4700 { 4701 AioContext *ctx = bdrv_get_aio_context(bs); 4702 BlockReopenQueue *queue; 4703 int ret; 4704 4705 GLOBAL_STATE_CODE(); 4706 4707 queue = bdrv_reopen_queue(NULL, bs, opts, keep_old_opts); 4708 4709 if (ctx != qemu_get_aio_context()) { 4710 aio_context_release(ctx); 4711 } 4712 ret = bdrv_reopen_multiple(queue, errp); 4713 4714 if (ctx != qemu_get_aio_context()) { 4715 aio_context_acquire(ctx); 4716 } 4717 4718 return ret; 4719 } 4720 4721 int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only, 4722 Error **errp) 4723 { 4724 QDict *opts = qdict_new(); 4725 4726 GLOBAL_STATE_CODE(); 4727 4728 qdict_put_bool(opts, BDRV_OPT_READ_ONLY, read_only); 4729 4730 return bdrv_reopen(bs, opts, true, errp); 4731 } 4732 4733 /* 4734 * Take a BDRVReopenState and check if the value of 'backing' in the 4735 * reopen_state->options QDict is valid or not. 4736 * 4737 * If 'backing' is missing from the QDict then return 0. 4738 * 4739 * If 'backing' contains the node name of the backing file of 4740 * reopen_state->bs then return 0. 4741 * 4742 * If 'backing' contains a different node name (or is null) then check 4743 * whether the current backing file can be replaced with the new one. 4744 * If that's the case then reopen_state->replace_backing_bs is set to 4745 * true and reopen_state->new_backing_bs contains a pointer to the new 4746 * backing BlockDriverState (or NULL). 4747 * 4748 * After calling this function, the transaction @tran may only be completed 4749 * while holding a writer lock for the graph. 4750 * 4751 * Return 0 on success, otherwise return < 0 and set @errp. 4752 * 4753 * The caller must hold the AioContext lock of @reopen_state->bs. 4754 * @reopen_state->bs can move to a different AioContext in this function. 4755 * Callers must make sure that their AioContext locking is still correct after 4756 * this. 4757 */ 4758 static int GRAPH_UNLOCKED 4759 bdrv_reopen_parse_file_or_backing(BDRVReopenState *reopen_state, 4760 bool is_backing, Transaction *tran, 4761 Error **errp) 4762 { 4763 BlockDriverState *bs = reopen_state->bs; 4764 BlockDriverState *new_child_bs; 4765 BlockDriverState *old_child_bs = is_backing ? child_bs(bs->backing) : 4766 child_bs(bs->file); 4767 const char *child_name = is_backing ? "backing" : "file"; 4768 QObject *value; 4769 const char *str; 4770 AioContext *ctx, *old_ctx; 4771 bool has_child; 4772 int ret; 4773 4774 GLOBAL_STATE_CODE(); 4775 4776 value = qdict_get(reopen_state->options, child_name); 4777 if (value == NULL) { 4778 return 0; 4779 } 4780 4781 switch (qobject_type(value)) { 4782 case QTYPE_QNULL: 4783 assert(is_backing); /* The 'file' option does not allow a null value */ 4784 new_child_bs = NULL; 4785 break; 4786 case QTYPE_QSTRING: 4787 str = qstring_get_str(qobject_to(QString, value)); 4788 new_child_bs = bdrv_lookup_bs(NULL, str, errp); 4789 if (new_child_bs == NULL) { 4790 return -EINVAL; 4791 } 4792 4793 bdrv_graph_rdlock_main_loop(); 4794 has_child = bdrv_recurse_has_child(new_child_bs, bs); 4795 bdrv_graph_rdunlock_main_loop(); 4796 4797 if (has_child) { 4798 error_setg(errp, "Making '%s' a %s child of '%s' would create a " 4799 "cycle", str, child_name, bs->node_name); 4800 return -EINVAL; 4801 } 4802 break; 4803 default: 4804 /* 4805 * The options QDict has been flattened, so 'backing' and 'file' 4806 * do not allow any other data type here. 4807 */ 4808 g_assert_not_reached(); 4809 } 4810 4811 if (old_child_bs == new_child_bs) { 4812 return 0; 4813 } 4814 4815 if (old_child_bs) { 4816 if (bdrv_skip_implicit_filters(old_child_bs) == new_child_bs) { 4817 return 0; 4818 } 4819 4820 if (old_child_bs->implicit) { 4821 error_setg(errp, "Cannot replace implicit %s child of %s", 4822 child_name, bs->node_name); 4823 return -EPERM; 4824 } 4825 } 4826 4827 if (bs->drv->is_filter && !old_child_bs) { 4828 /* 4829 * Filters always have a file or a backing child, so we are trying to 4830 * change wrong child 4831 */ 4832 error_setg(errp, "'%s' is a %s filter node that does not support a " 4833 "%s child", bs->node_name, bs->drv->format_name, child_name); 4834 return -EINVAL; 4835 } 4836 4837 if (is_backing) { 4838 reopen_state->old_backing_bs = old_child_bs; 4839 } else { 4840 reopen_state->old_file_bs = old_child_bs; 4841 } 4842 4843 if (old_child_bs) { 4844 bdrv_ref(old_child_bs); 4845 bdrv_drained_begin(old_child_bs); 4846 } 4847 4848 old_ctx = bdrv_get_aio_context(bs); 4849 ctx = bdrv_get_aio_context(new_child_bs); 4850 if (old_ctx != ctx) { 4851 aio_context_release(old_ctx); 4852 aio_context_acquire(ctx); 4853 } 4854 4855 bdrv_graph_wrlock(new_child_bs); 4856 4857 ret = bdrv_set_file_or_backing_noperm(bs, new_child_bs, is_backing, 4858 tran, errp); 4859 4860 bdrv_graph_wrunlock(); 4861 4862 if (old_ctx != ctx) { 4863 aio_context_release(ctx); 4864 aio_context_acquire(old_ctx); 4865 } 4866 4867 if (old_child_bs) { 4868 bdrv_drained_end(old_child_bs); 4869 bdrv_unref(old_child_bs); 4870 } 4871 4872 return ret; 4873 } 4874 4875 /* 4876 * Prepares a BlockDriverState for reopen. All changes are staged in the 4877 * 'opaque' field of the BDRVReopenState, which is used and allocated by 4878 * the block driver layer .bdrv_reopen_prepare() 4879 * 4880 * bs is the BlockDriverState to reopen 4881 * flags are the new open flags 4882 * queue is the reopen queue 4883 * 4884 * Returns 0 on success, non-zero on error. On error errp will be set 4885 * as well. 4886 * 4887 * On failure, bdrv_reopen_abort() will be called to clean up any data. 4888 * It is the responsibility of the caller to then call the abort() or 4889 * commit() for any other BDS that have been left in a prepare() state 4890 * 4891 * The caller must hold the AioContext lock of @reopen_state->bs. 4892 * 4893 * After calling this function, the transaction @change_child_tran may only be 4894 * completed while holding a writer lock for the graph. 4895 */ 4896 static int GRAPH_UNLOCKED 4897 bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, 4898 Transaction *change_child_tran, Error **errp) 4899 { 4900 int ret = -1; 4901 int old_flags; 4902 Error *local_err = NULL; 4903 BlockDriver *drv; 4904 QemuOpts *opts; 4905 QDict *orig_reopen_opts; 4906 char *discard = NULL; 4907 bool read_only; 4908 bool drv_prepared = false; 4909 4910 assert(reopen_state != NULL); 4911 assert(reopen_state->bs->drv != NULL); 4912 GLOBAL_STATE_CODE(); 4913 drv = reopen_state->bs->drv; 4914 4915 /* This function and each driver's bdrv_reopen_prepare() remove 4916 * entries from reopen_state->options as they are processed, so 4917 * we need to make a copy of the original QDict. */ 4918 orig_reopen_opts = qdict_clone_shallow(reopen_state->options); 4919 4920 /* Process generic block layer options */ 4921 opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort); 4922 if (!qemu_opts_absorb_qdict(opts, reopen_state->options, errp)) { 4923 ret = -EINVAL; 4924 goto error; 4925 } 4926 4927 /* This was already called in bdrv_reopen_queue_child() so the flags 4928 * are up-to-date. This time we simply want to remove the options from 4929 * QemuOpts in order to indicate that they have been processed. */ 4930 old_flags = reopen_state->flags; 4931 update_flags_from_options(&reopen_state->flags, opts); 4932 assert(old_flags == reopen_state->flags); 4933 4934 discard = qemu_opt_get_del(opts, BDRV_OPT_DISCARD); 4935 if (discard != NULL) { 4936 if (bdrv_parse_discard_flags(discard, &reopen_state->flags) != 0) { 4937 error_setg(errp, "Invalid discard option"); 4938 ret = -EINVAL; 4939 goto error; 4940 } 4941 } 4942 4943 reopen_state->detect_zeroes = 4944 bdrv_parse_detect_zeroes(opts, reopen_state->flags, &local_err); 4945 if (local_err) { 4946 error_propagate(errp, local_err); 4947 ret = -EINVAL; 4948 goto error; 4949 } 4950 4951 /* All other options (including node-name and driver) must be unchanged. 4952 * Put them back into the QDict, so that they are checked at the end 4953 * of this function. */ 4954 qemu_opts_to_qdict(opts, reopen_state->options); 4955 4956 /* If we are to stay read-only, do not allow permission change 4957 * to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is 4958 * not set, or if the BDS still has copy_on_read enabled */ 4959 read_only = !(reopen_state->flags & BDRV_O_RDWR); 4960 4961 bdrv_graph_rdlock_main_loop(); 4962 ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err); 4963 bdrv_graph_rdunlock_main_loop(); 4964 if (local_err) { 4965 error_propagate(errp, local_err); 4966 goto error; 4967 } 4968 4969 if (drv->bdrv_reopen_prepare) { 4970 /* 4971 * If a driver-specific option is missing, it means that we 4972 * should reset it to its default value. 4973 * But not all options allow that, so we need to check it first. 4974 */ 4975 ret = bdrv_reset_options_allowed(reopen_state->bs, 4976 reopen_state->options, errp); 4977 if (ret) { 4978 goto error; 4979 } 4980 4981 ret = drv->bdrv_reopen_prepare(reopen_state, queue, &local_err); 4982 if (ret) { 4983 if (local_err != NULL) { 4984 error_propagate(errp, local_err); 4985 } else { 4986 bdrv_graph_rdlock_main_loop(); 4987 bdrv_refresh_filename(reopen_state->bs); 4988 bdrv_graph_rdunlock_main_loop(); 4989 error_setg(errp, "failed while preparing to reopen image '%s'", 4990 reopen_state->bs->filename); 4991 } 4992 goto error; 4993 } 4994 } else { 4995 /* It is currently mandatory to have a bdrv_reopen_prepare() 4996 * handler for each supported drv. */ 4997 bdrv_graph_rdlock_main_loop(); 4998 error_setg(errp, "Block format '%s' used by node '%s' " 4999 "does not support reopening files", drv->format_name, 5000 bdrv_get_device_or_node_name(reopen_state->bs)); 5001 bdrv_graph_rdunlock_main_loop(); 5002 ret = -1; 5003 goto error; 5004 } 5005 5006 drv_prepared = true; 5007 5008 /* 5009 * We must provide the 'backing' option if the BDS has a backing 5010 * file or if the image file has a backing file name as part of 5011 * its metadata. Otherwise the 'backing' option can be omitted. 5012 */ 5013 if (drv->supports_backing && reopen_state->backing_missing && 5014 (reopen_state->bs->backing || reopen_state->bs->backing_file[0])) { 5015 error_setg(errp, "backing is missing for '%s'", 5016 reopen_state->bs->node_name); 5017 ret = -EINVAL; 5018 goto error; 5019 } 5020 5021 /* 5022 * Allow changing the 'backing' option. The new value can be 5023 * either a reference to an existing node (using its node name) 5024 * or NULL to simply detach the current backing file. 5025 */ 5026 ret = bdrv_reopen_parse_file_or_backing(reopen_state, true, 5027 change_child_tran, errp); 5028 if (ret < 0) { 5029 goto error; 5030 } 5031 qdict_del(reopen_state->options, "backing"); 5032 5033 /* Allow changing the 'file' option. In this case NULL is not allowed */ 5034 ret = bdrv_reopen_parse_file_or_backing(reopen_state, false, 5035 change_child_tran, errp); 5036 if (ret < 0) { 5037 goto error; 5038 } 5039 qdict_del(reopen_state->options, "file"); 5040 5041 /* Options that are not handled are only okay if they are unchanged 5042 * compared to the old state. It is expected that some options are only 5043 * used for the initial open, but not reopen (e.g. filename) */ 5044 if (qdict_size(reopen_state->options)) { 5045 const QDictEntry *entry = qdict_first(reopen_state->options); 5046 5047 GRAPH_RDLOCK_GUARD_MAINLOOP(); 5048 5049 do { 5050 QObject *new = entry->value; 5051 QObject *old = qdict_get(reopen_state->bs->options, entry->key); 5052 5053 /* Allow child references (child_name=node_name) as long as they 5054 * point to the current child (i.e. everything stays the same). */ 5055 if (qobject_type(new) == QTYPE_QSTRING) { 5056 BdrvChild *child; 5057 QLIST_FOREACH(child, &reopen_state->bs->children, next) { 5058 if (!strcmp(child->name, entry->key)) { 5059 break; 5060 } 5061 } 5062 5063 if (child) { 5064 if (!strcmp(child->bs->node_name, 5065 qstring_get_str(qobject_to(QString, new)))) { 5066 continue; /* Found child with this name, skip option */ 5067 } 5068 } 5069 } 5070 5071 /* 5072 * TODO: When using -drive to specify blockdev options, all values 5073 * will be strings; however, when using -blockdev, blockdev-add or 5074 * filenames using the json:{} pseudo-protocol, they will be 5075 * correctly typed. 5076 * In contrast, reopening options are (currently) always strings 5077 * (because you can only specify them through qemu-io; all other 5078 * callers do not specify any options). 5079 * Therefore, when using anything other than -drive to create a BDS, 5080 * this cannot detect non-string options as unchanged, because 5081 * qobject_is_equal() always returns false for objects of different 5082 * type. In the future, this should be remedied by correctly typing 5083 * all options. For now, this is not too big of an issue because 5084 * the user can simply omit options which cannot be changed anyway, 5085 * so they will stay unchanged. 5086 */ 5087 if (!qobject_is_equal(new, old)) { 5088 error_setg(errp, "Cannot change the option '%s'", entry->key); 5089 ret = -EINVAL; 5090 goto error; 5091 } 5092 } while ((entry = qdict_next(reopen_state->options, entry))); 5093 } 5094 5095 ret = 0; 5096 5097 /* Restore the original reopen_state->options QDict */ 5098 qobject_unref(reopen_state->options); 5099 reopen_state->options = qobject_ref(orig_reopen_opts); 5100 5101 error: 5102 if (ret < 0 && drv_prepared) { 5103 /* drv->bdrv_reopen_prepare() has succeeded, so we need to 5104 * call drv->bdrv_reopen_abort() before signaling an error 5105 * (bdrv_reopen_multiple() will not call bdrv_reopen_abort() 5106 * when the respective bdrv_reopen_prepare() has failed) */ 5107 if (drv->bdrv_reopen_abort) { 5108 drv->bdrv_reopen_abort(reopen_state); 5109 } 5110 } 5111 qemu_opts_del(opts); 5112 qobject_unref(orig_reopen_opts); 5113 g_free(discard); 5114 return ret; 5115 } 5116 5117 /* 5118 * Takes the staged changes for the reopen from bdrv_reopen_prepare(), and 5119 * makes them final by swapping the staging BlockDriverState contents into 5120 * the active BlockDriverState contents. 5121 */ 5122 static void GRAPH_UNLOCKED bdrv_reopen_commit(BDRVReopenState *reopen_state) 5123 { 5124 BlockDriver *drv; 5125 BlockDriverState *bs; 5126 BdrvChild *child; 5127 5128 assert(reopen_state != NULL); 5129 bs = reopen_state->bs; 5130 drv = bs->drv; 5131 assert(drv != NULL); 5132 GLOBAL_STATE_CODE(); 5133 5134 /* If there are any driver level actions to take */ 5135 if (drv->bdrv_reopen_commit) { 5136 drv->bdrv_reopen_commit(reopen_state); 5137 } 5138 5139 GRAPH_RDLOCK_GUARD_MAINLOOP(); 5140 5141 /* set BDS specific flags now */ 5142 qobject_unref(bs->explicit_options); 5143 qobject_unref(bs->options); 5144 qobject_ref(reopen_state->explicit_options); 5145 qobject_ref(reopen_state->options); 5146 5147 bs->explicit_options = reopen_state->explicit_options; 5148 bs->options = reopen_state->options; 5149 bs->open_flags = reopen_state->flags; 5150 bs->detect_zeroes = reopen_state->detect_zeroes; 5151 5152 /* Remove child references from bs->options and bs->explicit_options. 5153 * Child options were already removed in bdrv_reopen_queue_child() */ 5154 QLIST_FOREACH(child, &bs->children, next) { 5155 qdict_del(bs->explicit_options, child->name); 5156 qdict_del(bs->options, child->name); 5157 } 5158 /* backing is probably removed, so it's not handled by previous loop */ 5159 qdict_del(bs->explicit_options, "backing"); 5160 qdict_del(bs->options, "backing"); 5161 5162 bdrv_refresh_limits(bs, NULL, NULL); 5163 bdrv_refresh_total_sectors(bs, bs->total_sectors); 5164 } 5165 5166 /* 5167 * Abort the reopen, and delete and free the staged changes in 5168 * reopen_state 5169 */ 5170 static void GRAPH_UNLOCKED bdrv_reopen_abort(BDRVReopenState *reopen_state) 5171 { 5172 BlockDriver *drv; 5173 5174 assert(reopen_state != NULL); 5175 drv = reopen_state->bs->drv; 5176 assert(drv != NULL); 5177 GLOBAL_STATE_CODE(); 5178 5179 if (drv->bdrv_reopen_abort) { 5180 drv->bdrv_reopen_abort(reopen_state); 5181 } 5182 } 5183 5184 5185 static void bdrv_close(BlockDriverState *bs) 5186 { 5187 BdrvAioNotifier *ban, *ban_next; 5188 BdrvChild *child, *next; 5189 5190 GLOBAL_STATE_CODE(); 5191 assert(!bs->refcnt); 5192 5193 bdrv_drained_begin(bs); /* complete I/O */ 5194 bdrv_flush(bs); 5195 bdrv_drain(bs); /* in case flush left pending I/O */ 5196 5197 if (bs->drv) { 5198 if (bs->drv->bdrv_close) { 5199 /* Must unfreeze all children, so bdrv_unref_child() works */ 5200 bs->drv->bdrv_close(bs); 5201 } 5202 bs->drv = NULL; 5203 } 5204 5205 bdrv_graph_wrlock(bs); 5206 QLIST_FOREACH_SAFE(child, &bs->children, next, next) { 5207 bdrv_unref_child(bs, child); 5208 } 5209 bdrv_graph_wrunlock(); 5210 5211 assert(!bs->backing); 5212 assert(!bs->file); 5213 g_free(bs->opaque); 5214 bs->opaque = NULL; 5215 qatomic_set(&bs->copy_on_read, 0); 5216 bs->backing_file[0] = '\0'; 5217 bs->backing_format[0] = '\0'; 5218 bs->total_sectors = 0; 5219 bs->encrypted = false; 5220 bs->sg = false; 5221 qobject_unref(bs->options); 5222 qobject_unref(bs->explicit_options); 5223 bs->options = NULL; 5224 bs->explicit_options = NULL; 5225 qobject_unref(bs->full_open_options); 5226 bs->full_open_options = NULL; 5227 g_free(bs->block_status_cache); 5228 bs->block_status_cache = NULL; 5229 5230 bdrv_release_named_dirty_bitmaps(bs); 5231 assert(QLIST_EMPTY(&bs->dirty_bitmaps)); 5232 5233 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) { 5234 g_free(ban); 5235 } 5236 QLIST_INIT(&bs->aio_notifiers); 5237 bdrv_drained_end(bs); 5238 5239 /* 5240 * If we're still inside some bdrv_drain_all_begin()/end() sections, end 5241 * them now since this BDS won't exist anymore when bdrv_drain_all_end() 5242 * gets called. 5243 */ 5244 if (bs->quiesce_counter) { 5245 bdrv_drain_all_end_quiesce(bs); 5246 } 5247 } 5248 5249 void bdrv_close_all(void) 5250 { 5251 GLOBAL_STATE_CODE(); 5252 assert(job_next(NULL) == NULL); 5253 5254 /* Drop references from requests still in flight, such as canceled block 5255 * jobs whose AIO context has not been polled yet */ 5256 bdrv_drain_all(); 5257 5258 blk_remove_all_bs(); 5259 blockdev_close_all_bdrv_states(); 5260 5261 assert(QTAILQ_EMPTY(&all_bdrv_states)); 5262 } 5263 5264 static bool GRAPH_RDLOCK should_update_child(BdrvChild *c, BlockDriverState *to) 5265 { 5266 GQueue *queue; 5267 GHashTable *found; 5268 bool ret; 5269 5270 if (c->klass->stay_at_node) { 5271 return false; 5272 } 5273 5274 /* If the child @c belongs to the BDS @to, replacing the current 5275 * c->bs by @to would mean to create a loop. 5276 * 5277 * Such a case occurs when appending a BDS to a backing chain. 5278 * For instance, imagine the following chain: 5279 * 5280 * guest device -> node A -> further backing chain... 5281 * 5282 * Now we create a new BDS B which we want to put on top of this 5283 * chain, so we first attach A as its backing node: 5284 * 5285 * node B 5286 * | 5287 * v 5288 * guest device -> node A -> further backing chain... 5289 * 5290 * Finally we want to replace A by B. When doing that, we want to 5291 * replace all pointers to A by pointers to B -- except for the 5292 * pointer from B because (1) that would create a loop, and (2) 5293 * that pointer should simply stay intact: 5294 * 5295 * guest device -> node B 5296 * | 5297 * v 5298 * node A -> further backing chain... 5299 * 5300 * In general, when replacing a node A (c->bs) by a node B (@to), 5301 * if A is a child of B, that means we cannot replace A by B there 5302 * because that would create a loop. Silently detaching A from B 5303 * is also not really an option. So overall just leaving A in 5304 * place there is the most sensible choice. 5305 * 5306 * We would also create a loop in any cases where @c is only 5307 * indirectly referenced by @to. Prevent this by returning false 5308 * if @c is found (by breadth-first search) anywhere in the whole 5309 * subtree of @to. 5310 */ 5311 5312 ret = true; 5313 found = g_hash_table_new(NULL, NULL); 5314 g_hash_table_add(found, to); 5315 queue = g_queue_new(); 5316 g_queue_push_tail(queue, to); 5317 5318 while (!g_queue_is_empty(queue)) { 5319 BlockDriverState *v = g_queue_pop_head(queue); 5320 BdrvChild *c2; 5321 5322 QLIST_FOREACH(c2, &v->children, next) { 5323 if (c2 == c) { 5324 ret = false; 5325 break; 5326 } 5327 5328 if (g_hash_table_contains(found, c2->bs)) { 5329 continue; 5330 } 5331 5332 g_queue_push_tail(queue, c2->bs); 5333 g_hash_table_add(found, c2->bs); 5334 } 5335 } 5336 5337 g_queue_free(queue); 5338 g_hash_table_destroy(found); 5339 5340 return ret; 5341 } 5342 5343 static void bdrv_remove_child_commit(void *opaque) 5344 { 5345 GLOBAL_STATE_CODE(); 5346 bdrv_child_free(opaque); 5347 } 5348 5349 static TransactionActionDrv bdrv_remove_child_drv = { 5350 .commit = bdrv_remove_child_commit, 5351 }; 5352 5353 /* 5354 * Function doesn't update permissions, caller is responsible for this. 5355 * 5356 * @child->bs (if non-NULL) must be drained. 5357 * 5358 * After calling this function, the transaction @tran may only be completed 5359 * while holding a writer lock for the graph. 5360 */ 5361 static void GRAPH_WRLOCK bdrv_remove_child(BdrvChild *child, Transaction *tran) 5362 { 5363 if (!child) { 5364 return; 5365 } 5366 5367 if (child->bs) { 5368 assert(child->quiesced_parent); 5369 bdrv_replace_child_tran(child, NULL, tran); 5370 } 5371 5372 tran_add(tran, &bdrv_remove_child_drv, child); 5373 } 5374 5375 /* 5376 * Both @from and @to (if non-NULL) must be drained. @to must be kept drained 5377 * until the transaction is completed. 5378 * 5379 * After calling this function, the transaction @tran may only be completed 5380 * while holding a writer lock for the graph. 5381 */ 5382 static int GRAPH_WRLOCK 5383 bdrv_replace_node_noperm(BlockDriverState *from, 5384 BlockDriverState *to, 5385 bool auto_skip, Transaction *tran, 5386 Error **errp) 5387 { 5388 BdrvChild *c, *next; 5389 5390 GLOBAL_STATE_CODE(); 5391 5392 assert(from->quiesce_counter); 5393 assert(to->quiesce_counter); 5394 5395 QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) { 5396 assert(c->bs == from); 5397 if (!should_update_child(c, to)) { 5398 if (auto_skip) { 5399 continue; 5400 } 5401 error_setg(errp, "Should not change '%s' link to '%s'", 5402 c->name, from->node_name); 5403 return -EINVAL; 5404 } 5405 if (c->frozen) { 5406 error_setg(errp, "Cannot change '%s' link to '%s'", 5407 c->name, from->node_name); 5408 return -EPERM; 5409 } 5410 bdrv_replace_child_tran(c, to, tran); 5411 } 5412 5413 return 0; 5414 } 5415 5416 /* 5417 * With auto_skip=true bdrv_replace_node_common skips updating from parents 5418 * if it creates a parent-child relation loop or if parent is block-job. 5419 * 5420 * With auto_skip=false the error is returned if from has a parent which should 5421 * not be updated. 5422 * 5423 * With @detach_subchain=true @to must be in a backing chain of @from. In this 5424 * case backing link of the cow-parent of @to is removed. 5425 */ 5426 static int bdrv_replace_node_common(BlockDriverState *from, 5427 BlockDriverState *to, 5428 bool auto_skip, bool detach_subchain, 5429 Error **errp) 5430 { 5431 Transaction *tran = tran_new(); 5432 g_autoptr(GSList) refresh_list = NULL; 5433 BlockDriverState *to_cow_parent = NULL; 5434 int ret; 5435 5436 GLOBAL_STATE_CODE(); 5437 5438 /* Make sure that @from doesn't go away until we have successfully attached 5439 * all of its parents to @to. */ 5440 bdrv_ref(from); 5441 5442 assert(qemu_get_current_aio_context() == qemu_get_aio_context()); 5443 assert(bdrv_get_aio_context(from) == bdrv_get_aio_context(to)); 5444 bdrv_drained_begin(from); 5445 bdrv_drained_begin(to); 5446 5447 bdrv_graph_wrlock(to); 5448 5449 if (detach_subchain) { 5450 assert(bdrv_chain_contains(from, to)); 5451 assert(from != to); 5452 for (to_cow_parent = from; 5453 bdrv_filter_or_cow_bs(to_cow_parent) != to; 5454 to_cow_parent = bdrv_filter_or_cow_bs(to_cow_parent)) 5455 { 5456 ; 5457 } 5458 } 5459 5460 /* 5461 * Do the replacement without permission update. 5462 * Replacement may influence the permissions, we should calculate new 5463 * permissions based on new graph. If we fail, we'll roll-back the 5464 * replacement. 5465 */ 5466 ret = bdrv_replace_node_noperm(from, to, auto_skip, tran, errp); 5467 if (ret < 0) { 5468 goto out; 5469 } 5470 5471 if (detach_subchain) { 5472 /* to_cow_parent is already drained because from is drained */ 5473 bdrv_remove_child(bdrv_filter_or_cow_child(to_cow_parent), tran); 5474 } 5475 5476 refresh_list = g_slist_prepend(refresh_list, to); 5477 refresh_list = g_slist_prepend(refresh_list, from); 5478 5479 ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp); 5480 if (ret < 0) { 5481 goto out; 5482 } 5483 5484 ret = 0; 5485 5486 out: 5487 tran_finalize(tran, ret); 5488 bdrv_graph_wrunlock(); 5489 5490 bdrv_drained_end(to); 5491 bdrv_drained_end(from); 5492 bdrv_unref(from); 5493 5494 return ret; 5495 } 5496 5497 int bdrv_replace_node(BlockDriverState *from, BlockDriverState *to, 5498 Error **errp) 5499 { 5500 GLOBAL_STATE_CODE(); 5501 5502 return bdrv_replace_node_common(from, to, true, false, errp); 5503 } 5504 5505 int bdrv_drop_filter(BlockDriverState *bs, Error **errp) 5506 { 5507 BlockDriverState *child_bs; 5508 5509 GLOBAL_STATE_CODE(); 5510 bdrv_graph_rdlock_main_loop(); 5511 child_bs = bdrv_filter_or_cow_bs(bs); 5512 bdrv_graph_rdunlock_main_loop(); 5513 5514 return bdrv_replace_node_common(bs, child_bs, true, true, errp); 5515 } 5516 5517 /* 5518 * Add new bs contents at the top of an image chain while the chain is 5519 * live, while keeping required fields on the top layer. 5520 * 5521 * This will modify the BlockDriverState fields, and swap contents 5522 * between bs_new and bs_top. Both bs_new and bs_top are modified. 5523 * 5524 * bs_new must not be attached to a BlockBackend and must not have backing 5525 * child. 5526 * 5527 * This function does not create any image files. 5528 * 5529 * The caller must hold the AioContext lock for @bs_top. 5530 */ 5531 int bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top, 5532 Error **errp) 5533 { 5534 int ret; 5535 BdrvChild *child; 5536 Transaction *tran = tran_new(); 5537 AioContext *old_context, *new_context = NULL; 5538 5539 GLOBAL_STATE_CODE(); 5540 5541 assert(!bs_new->backing); 5542 5543 old_context = bdrv_get_aio_context(bs_top); 5544 bdrv_drained_begin(bs_top); 5545 5546 /* 5547 * bdrv_drained_begin() requires that only the AioContext of the drained 5548 * node is locked, and at this point it can still differ from the AioContext 5549 * of bs_top. 5550 */ 5551 new_context = bdrv_get_aio_context(bs_new); 5552 aio_context_release(old_context); 5553 aio_context_acquire(new_context); 5554 bdrv_drained_begin(bs_new); 5555 aio_context_release(new_context); 5556 aio_context_acquire(old_context); 5557 new_context = NULL; 5558 5559 bdrv_graph_wrlock(bs_top); 5560 5561 child = bdrv_attach_child_noperm(bs_new, bs_top, "backing", 5562 &child_of_bds, bdrv_backing_role(bs_new), 5563 tran, errp); 5564 if (!child) { 5565 ret = -EINVAL; 5566 goto out; 5567 } 5568 5569 /* 5570 * bdrv_attach_child_noperm could change the AioContext of bs_top and 5571 * bs_new, but at least they are in the same AioContext now. This is the 5572 * AioContext that we need to lock for the rest of the function. 5573 */ 5574 new_context = bdrv_get_aio_context(bs_top); 5575 5576 if (old_context != new_context) { 5577 aio_context_release(old_context); 5578 aio_context_acquire(new_context); 5579 } 5580 5581 ret = bdrv_replace_node_noperm(bs_top, bs_new, true, tran, errp); 5582 if (ret < 0) { 5583 goto out; 5584 } 5585 5586 ret = bdrv_refresh_perms(bs_new, tran, errp); 5587 out: 5588 tran_finalize(tran, ret); 5589 5590 bdrv_refresh_limits(bs_top, NULL, NULL); 5591 bdrv_graph_wrunlock(); 5592 5593 bdrv_drained_end(bs_top); 5594 bdrv_drained_end(bs_new); 5595 5596 if (new_context && old_context != new_context) { 5597 aio_context_release(new_context); 5598 aio_context_acquire(old_context); 5599 } 5600 5601 return ret; 5602 } 5603 5604 /* Not for empty child */ 5605 int bdrv_replace_child_bs(BdrvChild *child, BlockDriverState *new_bs, 5606 Error **errp) 5607 { 5608 int ret; 5609 Transaction *tran = tran_new(); 5610 g_autoptr(GSList) refresh_list = NULL; 5611 BlockDriverState *old_bs = child->bs; 5612 5613 GLOBAL_STATE_CODE(); 5614 5615 bdrv_ref(old_bs); 5616 bdrv_drained_begin(old_bs); 5617 bdrv_drained_begin(new_bs); 5618 bdrv_graph_wrlock(new_bs); 5619 5620 bdrv_replace_child_tran(child, new_bs, tran); 5621 5622 refresh_list = g_slist_prepend(refresh_list, old_bs); 5623 refresh_list = g_slist_prepend(refresh_list, new_bs); 5624 5625 ret = bdrv_list_refresh_perms(refresh_list, NULL, tran, errp); 5626 5627 tran_finalize(tran, ret); 5628 5629 bdrv_graph_wrunlock(); 5630 bdrv_drained_end(old_bs); 5631 bdrv_drained_end(new_bs); 5632 bdrv_unref(old_bs); 5633 5634 return ret; 5635 } 5636 5637 static void bdrv_delete(BlockDriverState *bs) 5638 { 5639 assert(bdrv_op_blocker_is_empty(bs)); 5640 assert(!bs->refcnt); 5641 GLOBAL_STATE_CODE(); 5642 5643 /* remove from list, if necessary */ 5644 if (bs->node_name[0] != '\0') { 5645 QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list); 5646 } 5647 QTAILQ_REMOVE(&all_bdrv_states, bs, bs_list); 5648 5649 bdrv_close(bs); 5650 5651 qemu_mutex_destroy(&bs->reqs_lock); 5652 5653 g_free(bs); 5654 } 5655 5656 5657 /* 5658 * Replace @bs by newly created block node. 5659 * 5660 * @options is a QDict of options to pass to the block drivers, or NULL for an 5661 * empty set of options. The reference to the QDict belongs to the block layer 5662 * after the call (even on failure), so if the caller intends to reuse the 5663 * dictionary, it needs to use qobject_ref() before calling bdrv_open. 5664 * 5665 * The caller holds the AioContext lock for @bs. It must make sure that @bs 5666 * stays in the same AioContext, i.e. @options must not refer to nodes in a 5667 * different AioContext. 5668 */ 5669 BlockDriverState *bdrv_insert_node(BlockDriverState *bs, QDict *options, 5670 int flags, Error **errp) 5671 { 5672 ERRP_GUARD(); 5673 int ret; 5674 AioContext *ctx = bdrv_get_aio_context(bs); 5675 BlockDriverState *new_node_bs = NULL; 5676 const char *drvname, *node_name; 5677 BlockDriver *drv; 5678 5679 drvname = qdict_get_try_str(options, "driver"); 5680 if (!drvname) { 5681 error_setg(errp, "driver is not specified"); 5682 goto fail; 5683 } 5684 5685 drv = bdrv_find_format(drvname); 5686 if (!drv) { 5687 error_setg(errp, "Unknown driver: '%s'", drvname); 5688 goto fail; 5689 } 5690 5691 node_name = qdict_get_try_str(options, "node-name"); 5692 5693 GLOBAL_STATE_CODE(); 5694 5695 aio_context_release(ctx); 5696 aio_context_acquire(qemu_get_aio_context()); 5697 new_node_bs = bdrv_new_open_driver_opts(drv, node_name, options, flags, 5698 errp); 5699 aio_context_release(qemu_get_aio_context()); 5700 aio_context_acquire(ctx); 5701 assert(bdrv_get_aio_context(bs) == ctx); 5702 5703 options = NULL; /* bdrv_new_open_driver() eats options */ 5704 if (!new_node_bs) { 5705 error_prepend(errp, "Could not create node: "); 5706 goto fail; 5707 } 5708 5709 bdrv_drained_begin(bs); 5710 ret = bdrv_replace_node(bs, new_node_bs, errp); 5711 bdrv_drained_end(bs); 5712 5713 if (ret < 0) { 5714 error_prepend(errp, "Could not replace node: "); 5715 goto fail; 5716 } 5717 5718 return new_node_bs; 5719 5720 fail: 5721 qobject_unref(options); 5722 bdrv_unref(new_node_bs); 5723 return NULL; 5724 } 5725 5726 /* 5727 * Run consistency checks on an image 5728 * 5729 * Returns 0 if the check could be completed (it doesn't mean that the image is 5730 * free of errors) or -errno when an internal error occurred. The results of the 5731 * check are stored in res. 5732 */ 5733 int coroutine_fn bdrv_co_check(BlockDriverState *bs, 5734 BdrvCheckResult *res, BdrvCheckMode fix) 5735 { 5736 IO_CODE(); 5737 assert_bdrv_graph_readable(); 5738 if (bs->drv == NULL) { 5739 return -ENOMEDIUM; 5740 } 5741 if (bs->drv->bdrv_co_check == NULL) { 5742 return -ENOTSUP; 5743 } 5744 5745 memset(res, 0, sizeof(*res)); 5746 return bs->drv->bdrv_co_check(bs, res, fix); 5747 } 5748 5749 /* 5750 * Return values: 5751 * 0 - success 5752 * -EINVAL - backing format specified, but no file 5753 * -ENOSPC - can't update the backing file because no space is left in the 5754 * image file header 5755 * -ENOTSUP - format driver doesn't support changing the backing file 5756 */ 5757 int bdrv_change_backing_file(BlockDriverState *bs, const char *backing_file, 5758 const char *backing_fmt, bool require) 5759 { 5760 BlockDriver *drv = bs->drv; 5761 int ret; 5762 5763 GLOBAL_STATE_CODE(); 5764 5765 if (!drv) { 5766 return -ENOMEDIUM; 5767 } 5768 5769 /* Backing file format doesn't make sense without a backing file */ 5770 if (backing_fmt && !backing_file) { 5771 return -EINVAL; 5772 } 5773 5774 if (require && backing_file && !backing_fmt) { 5775 return -EINVAL; 5776 } 5777 5778 if (drv->bdrv_change_backing_file != NULL) { 5779 ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt); 5780 } else { 5781 ret = -ENOTSUP; 5782 } 5783 5784 if (ret == 0) { 5785 pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: ""); 5786 pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: ""); 5787 pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file), 5788 backing_file ?: ""); 5789 } 5790 return ret; 5791 } 5792 5793 /* 5794 * Finds the first non-filter node above bs in the chain between 5795 * active and bs. The returned node is either an immediate parent of 5796 * bs, or there are only filter nodes between the two. 5797 * 5798 * Returns NULL if bs is not found in active's image chain, 5799 * or if active == bs. 5800 * 5801 * Returns the bottommost base image if bs == NULL. 5802 */ 5803 BlockDriverState *bdrv_find_overlay(BlockDriverState *active, 5804 BlockDriverState *bs) 5805 { 5806 5807 GLOBAL_STATE_CODE(); 5808 5809 bs = bdrv_skip_filters(bs); 5810 active = bdrv_skip_filters(active); 5811 5812 while (active) { 5813 BlockDriverState *next = bdrv_backing_chain_next(active); 5814 if (bs == next) { 5815 return active; 5816 } 5817 active = next; 5818 } 5819 5820 return NULL; 5821 } 5822 5823 /* Given a BDS, searches for the base layer. */ 5824 BlockDriverState *bdrv_find_base(BlockDriverState *bs) 5825 { 5826 GLOBAL_STATE_CODE(); 5827 5828 return bdrv_find_overlay(bs, NULL); 5829 } 5830 5831 /* 5832 * Return true if at least one of the COW (backing) and filter links 5833 * between @bs and @base is frozen. @errp is set if that's the case. 5834 * @base must be reachable from @bs, or NULL. 5835 */ 5836 bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base, 5837 Error **errp) 5838 { 5839 BlockDriverState *i; 5840 BdrvChild *child; 5841 5842 GLOBAL_STATE_CODE(); 5843 5844 for (i = bs; i != base; i = child_bs(child)) { 5845 child = bdrv_filter_or_cow_child(i); 5846 5847 if (child && child->frozen) { 5848 error_setg(errp, "Cannot change '%s' link from '%s' to '%s'", 5849 child->name, i->node_name, child->bs->node_name); 5850 return true; 5851 } 5852 } 5853 5854 return false; 5855 } 5856 5857 /* 5858 * Freeze all COW (backing) and filter links between @bs and @base. 5859 * If any of the links is already frozen the operation is aborted and 5860 * none of the links are modified. 5861 * @base must be reachable from @bs, or NULL. 5862 * Returns 0 on success. On failure returns < 0 and sets @errp. 5863 */ 5864 int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base, 5865 Error **errp) 5866 { 5867 BlockDriverState *i; 5868 BdrvChild *child; 5869 5870 GLOBAL_STATE_CODE(); 5871 5872 if (bdrv_is_backing_chain_frozen(bs, base, errp)) { 5873 return -EPERM; 5874 } 5875 5876 for (i = bs; i != base; i = child_bs(child)) { 5877 child = bdrv_filter_or_cow_child(i); 5878 if (child && child->bs->never_freeze) { 5879 error_setg(errp, "Cannot freeze '%s' link to '%s'", 5880 child->name, child->bs->node_name); 5881 return -EPERM; 5882 } 5883 } 5884 5885 for (i = bs; i != base; i = child_bs(child)) { 5886 child = bdrv_filter_or_cow_child(i); 5887 if (child) { 5888 child->frozen = true; 5889 } 5890 } 5891 5892 return 0; 5893 } 5894 5895 /* 5896 * Unfreeze all COW (backing) and filter links between @bs and @base. 5897 * The caller must ensure that all links are frozen before using this 5898 * function. 5899 * @base must be reachable from @bs, or NULL. 5900 */ 5901 void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base) 5902 { 5903 BlockDriverState *i; 5904 BdrvChild *child; 5905 5906 GLOBAL_STATE_CODE(); 5907 5908 for (i = bs; i != base; i = child_bs(child)) { 5909 child = bdrv_filter_or_cow_child(i); 5910 if (child) { 5911 assert(child->frozen); 5912 child->frozen = false; 5913 } 5914 } 5915 } 5916 5917 /* 5918 * Drops images above 'base' up to and including 'top', and sets the image 5919 * above 'top' to have base as its backing file. 5920 * 5921 * Requires that the overlay to 'top' is opened r/w, so that the backing file 5922 * information in 'bs' can be properly updated. 5923 * 5924 * E.g., this will convert the following chain: 5925 * bottom <- base <- intermediate <- top <- active 5926 * 5927 * to 5928 * 5929 * bottom <- base <- active 5930 * 5931 * It is allowed for bottom==base, in which case it converts: 5932 * 5933 * base <- intermediate <- top <- active 5934 * 5935 * to 5936 * 5937 * base <- active 5938 * 5939 * If backing_file_str is non-NULL, it will be used when modifying top's 5940 * overlay image metadata. 5941 * 5942 * Error conditions: 5943 * if active == top, that is considered an error 5944 * 5945 */ 5946 int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base, 5947 const char *backing_file_str) 5948 { 5949 BlockDriverState *explicit_top = top; 5950 bool update_inherits_from; 5951 BdrvChild *c; 5952 Error *local_err = NULL; 5953 int ret = -EIO; 5954 g_autoptr(GSList) updated_children = NULL; 5955 GSList *p; 5956 5957 GLOBAL_STATE_CODE(); 5958 5959 bdrv_ref(top); 5960 bdrv_drained_begin(base); 5961 bdrv_graph_rdlock_main_loop(); 5962 5963 if (!top->drv || !base->drv) { 5964 goto exit; 5965 } 5966 5967 /* Make sure that base is in the backing chain of top */ 5968 if (!bdrv_chain_contains(top, base)) { 5969 goto exit; 5970 } 5971 5972 /* If 'base' recursively inherits from 'top' then we should set 5973 * base->inherits_from to top->inherits_from after 'top' and all 5974 * other intermediate nodes have been dropped. 5975 * If 'top' is an implicit node (e.g. "commit_top") we should skip 5976 * it because no one inherits from it. We use explicit_top for that. */ 5977 explicit_top = bdrv_skip_implicit_filters(explicit_top); 5978 update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top); 5979 5980 /* success - we can delete the intermediate states, and link top->base */ 5981 if (!backing_file_str) { 5982 bdrv_refresh_filename(base); 5983 backing_file_str = base->filename; 5984 } 5985 5986 QLIST_FOREACH(c, &top->parents, next_parent) { 5987 updated_children = g_slist_prepend(updated_children, c); 5988 } 5989 5990 /* 5991 * It seems correct to pass detach_subchain=true here, but it triggers 5992 * one more yet not fixed bug, when due to nested aio_poll loop we switch to 5993 * another drained section, which modify the graph (for example, removing 5994 * the child, which we keep in updated_children list). So, it's a TODO. 5995 * 5996 * Note, bug triggered if pass detach_subchain=true here and run 5997 * test-bdrv-drain. test_drop_intermediate_poll() test-case will crash. 5998 * That's a FIXME. 5999 */ 6000 bdrv_replace_node_common(top, base, false, false, &local_err); 6001 if (local_err) { 6002 error_report_err(local_err); 6003 goto exit; 6004 } 6005 6006 for (p = updated_children; p; p = p->next) { 6007 c = p->data; 6008 6009 if (c->klass->update_filename) { 6010 ret = c->klass->update_filename(c, base, backing_file_str, 6011 &local_err); 6012 if (ret < 0) { 6013 /* 6014 * TODO: Actually, we want to rollback all previous iterations 6015 * of this loop, and (which is almost impossible) previous 6016 * bdrv_replace_node()... 6017 * 6018 * Note, that c->klass->update_filename may lead to permission 6019 * update, so it's a bad idea to call it inside permission 6020 * update transaction of bdrv_replace_node. 6021 */ 6022 error_report_err(local_err); 6023 goto exit; 6024 } 6025 } 6026 } 6027 6028 if (update_inherits_from) { 6029 base->inherits_from = explicit_top->inherits_from; 6030 } 6031 6032 ret = 0; 6033 exit: 6034 bdrv_graph_rdunlock_main_loop(); 6035 bdrv_drained_end(base); 6036 bdrv_unref(top); 6037 return ret; 6038 } 6039 6040 /** 6041 * Implementation of BlockDriver.bdrv_co_get_allocated_file_size() that 6042 * sums the size of all data-bearing children. (This excludes backing 6043 * children.) 6044 */ 6045 static int64_t coroutine_fn GRAPH_RDLOCK 6046 bdrv_sum_allocated_file_size(BlockDriverState *bs) 6047 { 6048 BdrvChild *child; 6049 int64_t child_size, sum = 0; 6050 6051 QLIST_FOREACH(child, &bs->children, next) { 6052 if (child->role & (BDRV_CHILD_DATA | BDRV_CHILD_METADATA | 6053 BDRV_CHILD_FILTERED)) 6054 { 6055 child_size = bdrv_co_get_allocated_file_size(child->bs); 6056 if (child_size < 0) { 6057 return child_size; 6058 } 6059 sum += child_size; 6060 } 6061 } 6062 6063 return sum; 6064 } 6065 6066 /** 6067 * Length of a allocated file in bytes. Sparse files are counted by actual 6068 * allocated space. Return < 0 if error or unknown. 6069 */ 6070 int64_t coroutine_fn bdrv_co_get_allocated_file_size(BlockDriverState *bs) 6071 { 6072 BlockDriver *drv = bs->drv; 6073 IO_CODE(); 6074 assert_bdrv_graph_readable(); 6075 6076 if (!drv) { 6077 return -ENOMEDIUM; 6078 } 6079 if (drv->bdrv_co_get_allocated_file_size) { 6080 return drv->bdrv_co_get_allocated_file_size(bs); 6081 } 6082 6083 if (drv->bdrv_file_open) { 6084 /* 6085 * Protocol drivers default to -ENOTSUP (most of their data is 6086 * not stored in any of their children (if they even have any), 6087 * so there is no generic way to figure it out). 6088 */ 6089 return -ENOTSUP; 6090 } else if (drv->is_filter) { 6091 /* Filter drivers default to the size of their filtered child */ 6092 return bdrv_co_get_allocated_file_size(bdrv_filter_bs(bs)); 6093 } else { 6094 /* Other drivers default to summing their children's sizes */ 6095 return bdrv_sum_allocated_file_size(bs); 6096 } 6097 } 6098 6099 /* 6100 * bdrv_measure: 6101 * @drv: Format driver 6102 * @opts: Creation options for new image 6103 * @in_bs: Existing image containing data for new image (may be NULL) 6104 * @errp: Error object 6105 * Returns: A #BlockMeasureInfo (free using qapi_free_BlockMeasureInfo()) 6106 * or NULL on error 6107 * 6108 * Calculate file size required to create a new image. 6109 * 6110 * If @in_bs is given then space for allocated clusters and zero clusters 6111 * from that image are included in the calculation. If @opts contains a 6112 * backing file that is shared by @in_bs then backing clusters may be omitted 6113 * from the calculation. 6114 * 6115 * If @in_bs is NULL then the calculation includes no allocated clusters 6116 * unless a preallocation option is given in @opts. 6117 * 6118 * Note that @in_bs may use a different BlockDriver from @drv. 6119 * 6120 * If an error occurs the @errp pointer is set. 6121 */ 6122 BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts, 6123 BlockDriverState *in_bs, Error **errp) 6124 { 6125 IO_CODE(); 6126 if (!drv->bdrv_measure) { 6127 error_setg(errp, "Block driver '%s' does not support size measurement", 6128 drv->format_name); 6129 return NULL; 6130 } 6131 6132 return drv->bdrv_measure(opts, in_bs, errp); 6133 } 6134 6135 /** 6136 * Return number of sectors on success, -errno on error. 6137 */ 6138 int64_t coroutine_fn bdrv_co_nb_sectors(BlockDriverState *bs) 6139 { 6140 BlockDriver *drv = bs->drv; 6141 IO_CODE(); 6142 assert_bdrv_graph_readable(); 6143 6144 if (!drv) 6145 return -ENOMEDIUM; 6146 6147 if (bs->bl.has_variable_length) { 6148 int ret = bdrv_co_refresh_total_sectors(bs, bs->total_sectors); 6149 if (ret < 0) { 6150 return ret; 6151 } 6152 } 6153 return bs->total_sectors; 6154 } 6155 6156 /* 6157 * This wrapper is written by hand because this function is in the hot I/O path, 6158 * via blk_get_geometry. 6159 */ 6160 int64_t coroutine_mixed_fn bdrv_nb_sectors(BlockDriverState *bs) 6161 { 6162 BlockDriver *drv = bs->drv; 6163 IO_CODE(); 6164 6165 if (!drv) 6166 return -ENOMEDIUM; 6167 6168 if (bs->bl.has_variable_length) { 6169 int ret = bdrv_refresh_total_sectors(bs, bs->total_sectors); 6170 if (ret < 0) { 6171 return ret; 6172 } 6173 } 6174 6175 return bs->total_sectors; 6176 } 6177 6178 /** 6179 * Return length in bytes on success, -errno on error. 6180 * The length is always a multiple of BDRV_SECTOR_SIZE. 6181 */ 6182 int64_t coroutine_fn bdrv_co_getlength(BlockDriverState *bs) 6183 { 6184 int64_t ret; 6185 IO_CODE(); 6186 assert_bdrv_graph_readable(); 6187 6188 ret = bdrv_co_nb_sectors(bs); 6189 if (ret < 0) { 6190 return ret; 6191 } 6192 if (ret > INT64_MAX / BDRV_SECTOR_SIZE) { 6193 return -EFBIG; 6194 } 6195 return ret * BDRV_SECTOR_SIZE; 6196 } 6197 6198 bool bdrv_is_sg(BlockDriverState *bs) 6199 { 6200 IO_CODE(); 6201 return bs->sg; 6202 } 6203 6204 /** 6205 * Return whether the given node supports compressed writes. 6206 */ 6207 bool bdrv_supports_compressed_writes(BlockDriverState *bs) 6208 { 6209 BlockDriverState *filtered; 6210 IO_CODE(); 6211 6212 if (!bs->drv || !block_driver_can_compress(bs->drv)) { 6213 return false; 6214 } 6215 6216 filtered = bdrv_filter_bs(bs); 6217 if (filtered) { 6218 /* 6219 * Filters can only forward compressed writes, so we have to 6220 * check the child. 6221 */ 6222 return bdrv_supports_compressed_writes(filtered); 6223 } 6224 6225 return true; 6226 } 6227 6228 const char *bdrv_get_format_name(BlockDriverState *bs) 6229 { 6230 IO_CODE(); 6231 return bs->drv ? bs->drv->format_name : NULL; 6232 } 6233 6234 static int qsort_strcmp(const void *a, const void *b) 6235 { 6236 return strcmp(*(char *const *)a, *(char *const *)b); 6237 } 6238 6239 void bdrv_iterate_format(void (*it)(void *opaque, const char *name), 6240 void *opaque, bool read_only) 6241 { 6242 BlockDriver *drv; 6243 int count = 0; 6244 int i; 6245 const char **formats = NULL; 6246 6247 GLOBAL_STATE_CODE(); 6248 6249 QLIST_FOREACH(drv, &bdrv_drivers, list) { 6250 if (drv->format_name) { 6251 bool found = false; 6252 6253 if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, read_only)) { 6254 continue; 6255 } 6256 6257 i = count; 6258 while (formats && i && !found) { 6259 found = !strcmp(formats[--i], drv->format_name); 6260 } 6261 6262 if (!found) { 6263 formats = g_renew(const char *, formats, count + 1); 6264 formats[count++] = drv->format_name; 6265 } 6266 } 6267 } 6268 6269 for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); i++) { 6270 const char *format_name = block_driver_modules[i].format_name; 6271 6272 if (format_name) { 6273 bool found = false; 6274 int j = count; 6275 6276 if (use_bdrv_whitelist && 6277 !bdrv_format_is_whitelisted(format_name, read_only)) { 6278 continue; 6279 } 6280 6281 while (formats && j && !found) { 6282 found = !strcmp(formats[--j], format_name); 6283 } 6284 6285 if (!found) { 6286 formats = g_renew(const char *, formats, count + 1); 6287 formats[count++] = format_name; 6288 } 6289 } 6290 } 6291 6292 qsort(formats, count, sizeof(formats[0]), qsort_strcmp); 6293 6294 for (i = 0; i < count; i++) { 6295 it(opaque, formats[i]); 6296 } 6297 6298 g_free(formats); 6299 } 6300 6301 /* This function is to find a node in the bs graph */ 6302 BlockDriverState *bdrv_find_node(const char *node_name) 6303 { 6304 BlockDriverState *bs; 6305 6306 assert(node_name); 6307 GLOBAL_STATE_CODE(); 6308 6309 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { 6310 if (!strcmp(node_name, bs->node_name)) { 6311 return bs; 6312 } 6313 } 6314 return NULL; 6315 } 6316 6317 /* Put this QMP function here so it can access the static graph_bdrv_states. */ 6318 BlockDeviceInfoList *bdrv_named_nodes_list(bool flat, 6319 Error **errp) 6320 { 6321 BlockDeviceInfoList *list; 6322 BlockDriverState *bs; 6323 6324 GLOBAL_STATE_CODE(); 6325 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6326 6327 list = NULL; 6328 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { 6329 BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, flat, errp); 6330 if (!info) { 6331 qapi_free_BlockDeviceInfoList(list); 6332 return NULL; 6333 } 6334 QAPI_LIST_PREPEND(list, info); 6335 } 6336 6337 return list; 6338 } 6339 6340 typedef struct XDbgBlockGraphConstructor { 6341 XDbgBlockGraph *graph; 6342 GHashTable *graph_nodes; 6343 } XDbgBlockGraphConstructor; 6344 6345 static XDbgBlockGraphConstructor *xdbg_graph_new(void) 6346 { 6347 XDbgBlockGraphConstructor *gr = g_new(XDbgBlockGraphConstructor, 1); 6348 6349 gr->graph = g_new0(XDbgBlockGraph, 1); 6350 gr->graph_nodes = g_hash_table_new(NULL, NULL); 6351 6352 return gr; 6353 } 6354 6355 static XDbgBlockGraph *xdbg_graph_finalize(XDbgBlockGraphConstructor *gr) 6356 { 6357 XDbgBlockGraph *graph = gr->graph; 6358 6359 g_hash_table_destroy(gr->graph_nodes); 6360 g_free(gr); 6361 6362 return graph; 6363 } 6364 6365 static uintptr_t xdbg_graph_node_num(XDbgBlockGraphConstructor *gr, void *node) 6366 { 6367 uintptr_t ret = (uintptr_t)g_hash_table_lookup(gr->graph_nodes, node); 6368 6369 if (ret != 0) { 6370 return ret; 6371 } 6372 6373 /* 6374 * Start counting from 1, not 0, because 0 interferes with not-found (NULL) 6375 * answer of g_hash_table_lookup. 6376 */ 6377 ret = g_hash_table_size(gr->graph_nodes) + 1; 6378 g_hash_table_insert(gr->graph_nodes, node, (void *)ret); 6379 6380 return ret; 6381 } 6382 6383 static void xdbg_graph_add_node(XDbgBlockGraphConstructor *gr, void *node, 6384 XDbgBlockGraphNodeType type, const char *name) 6385 { 6386 XDbgBlockGraphNode *n; 6387 6388 n = g_new0(XDbgBlockGraphNode, 1); 6389 6390 n->id = xdbg_graph_node_num(gr, node); 6391 n->type = type; 6392 n->name = g_strdup(name); 6393 6394 QAPI_LIST_PREPEND(gr->graph->nodes, n); 6395 } 6396 6397 static void xdbg_graph_add_edge(XDbgBlockGraphConstructor *gr, void *parent, 6398 const BdrvChild *child) 6399 { 6400 BlockPermission qapi_perm; 6401 XDbgBlockGraphEdge *edge; 6402 GLOBAL_STATE_CODE(); 6403 6404 edge = g_new0(XDbgBlockGraphEdge, 1); 6405 6406 edge->parent = xdbg_graph_node_num(gr, parent); 6407 edge->child = xdbg_graph_node_num(gr, child->bs); 6408 edge->name = g_strdup(child->name); 6409 6410 for (qapi_perm = 0; qapi_perm < BLOCK_PERMISSION__MAX; qapi_perm++) { 6411 uint64_t flag = bdrv_qapi_perm_to_blk_perm(qapi_perm); 6412 6413 if (flag & child->perm) { 6414 QAPI_LIST_PREPEND(edge->perm, qapi_perm); 6415 } 6416 if (flag & child->shared_perm) { 6417 QAPI_LIST_PREPEND(edge->shared_perm, qapi_perm); 6418 } 6419 } 6420 6421 QAPI_LIST_PREPEND(gr->graph->edges, edge); 6422 } 6423 6424 6425 XDbgBlockGraph *bdrv_get_xdbg_block_graph(Error **errp) 6426 { 6427 BlockBackend *blk; 6428 BlockJob *job; 6429 BlockDriverState *bs; 6430 BdrvChild *child; 6431 XDbgBlockGraphConstructor *gr = xdbg_graph_new(); 6432 6433 GLOBAL_STATE_CODE(); 6434 6435 for (blk = blk_all_next(NULL); blk; blk = blk_all_next(blk)) { 6436 char *allocated_name = NULL; 6437 const char *name = blk_name(blk); 6438 6439 if (!*name) { 6440 name = allocated_name = blk_get_attached_dev_id(blk); 6441 } 6442 xdbg_graph_add_node(gr, blk, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_BACKEND, 6443 name); 6444 g_free(allocated_name); 6445 if (blk_root(blk)) { 6446 xdbg_graph_add_edge(gr, blk, blk_root(blk)); 6447 } 6448 } 6449 6450 WITH_JOB_LOCK_GUARD() { 6451 for (job = block_job_next_locked(NULL); job; 6452 job = block_job_next_locked(job)) { 6453 GSList *el; 6454 6455 xdbg_graph_add_node(gr, job, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_JOB, 6456 job->job.id); 6457 for (el = job->nodes; el; el = el->next) { 6458 xdbg_graph_add_edge(gr, job, (BdrvChild *)el->data); 6459 } 6460 } 6461 } 6462 6463 QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) { 6464 xdbg_graph_add_node(gr, bs, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_DRIVER, 6465 bs->node_name); 6466 QLIST_FOREACH(child, &bs->children, next) { 6467 xdbg_graph_add_edge(gr, bs, child); 6468 } 6469 } 6470 6471 return xdbg_graph_finalize(gr); 6472 } 6473 6474 BlockDriverState *bdrv_lookup_bs(const char *device, 6475 const char *node_name, 6476 Error **errp) 6477 { 6478 BlockBackend *blk; 6479 BlockDriverState *bs; 6480 6481 GLOBAL_STATE_CODE(); 6482 6483 if (device) { 6484 blk = blk_by_name(device); 6485 6486 if (blk) { 6487 bs = blk_bs(blk); 6488 if (!bs) { 6489 error_setg(errp, "Device '%s' has no medium", device); 6490 } 6491 6492 return bs; 6493 } 6494 } 6495 6496 if (node_name) { 6497 bs = bdrv_find_node(node_name); 6498 6499 if (bs) { 6500 return bs; 6501 } 6502 } 6503 6504 error_setg(errp, "Cannot find device=\'%s\' nor node-name=\'%s\'", 6505 device ? device : "", 6506 node_name ? node_name : ""); 6507 return NULL; 6508 } 6509 6510 /* If 'base' is in the same chain as 'top', return true. Otherwise, 6511 * return false. If either argument is NULL, return false. */ 6512 bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base) 6513 { 6514 6515 GLOBAL_STATE_CODE(); 6516 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6517 6518 while (top && top != base) { 6519 top = bdrv_filter_or_cow_bs(top); 6520 } 6521 6522 return top != NULL; 6523 } 6524 6525 BlockDriverState *bdrv_next_node(BlockDriverState *bs) 6526 { 6527 GLOBAL_STATE_CODE(); 6528 if (!bs) { 6529 return QTAILQ_FIRST(&graph_bdrv_states); 6530 } 6531 return QTAILQ_NEXT(bs, node_list); 6532 } 6533 6534 BlockDriverState *bdrv_next_all_states(BlockDriverState *bs) 6535 { 6536 GLOBAL_STATE_CODE(); 6537 if (!bs) { 6538 return QTAILQ_FIRST(&all_bdrv_states); 6539 } 6540 return QTAILQ_NEXT(bs, bs_list); 6541 } 6542 6543 const char *bdrv_get_node_name(const BlockDriverState *bs) 6544 { 6545 IO_CODE(); 6546 return bs->node_name; 6547 } 6548 6549 const char *bdrv_get_parent_name(const BlockDriverState *bs) 6550 { 6551 BdrvChild *c; 6552 const char *name; 6553 IO_CODE(); 6554 6555 /* If multiple parents have a name, just pick the first one. */ 6556 QLIST_FOREACH(c, &bs->parents, next_parent) { 6557 if (c->klass->get_name) { 6558 name = c->klass->get_name(c); 6559 if (name && *name) { 6560 return name; 6561 } 6562 } 6563 } 6564 6565 return NULL; 6566 } 6567 6568 /* TODO check what callers really want: bs->node_name or blk_name() */ 6569 const char *bdrv_get_device_name(const BlockDriverState *bs) 6570 { 6571 IO_CODE(); 6572 return bdrv_get_parent_name(bs) ?: ""; 6573 } 6574 6575 /* This can be used to identify nodes that might not have a device 6576 * name associated. Since node and device names live in the same 6577 * namespace, the result is unambiguous. The exception is if both are 6578 * absent, then this returns an empty (non-null) string. */ 6579 const char *bdrv_get_device_or_node_name(const BlockDriverState *bs) 6580 { 6581 IO_CODE(); 6582 return bdrv_get_parent_name(bs) ?: bs->node_name; 6583 } 6584 6585 int bdrv_get_flags(BlockDriverState *bs) 6586 { 6587 IO_CODE(); 6588 return bs->open_flags; 6589 } 6590 6591 int bdrv_has_zero_init_1(BlockDriverState *bs) 6592 { 6593 GLOBAL_STATE_CODE(); 6594 return 1; 6595 } 6596 6597 int coroutine_mixed_fn bdrv_has_zero_init(BlockDriverState *bs) 6598 { 6599 BlockDriverState *filtered; 6600 GLOBAL_STATE_CODE(); 6601 6602 if (!bs->drv) { 6603 return 0; 6604 } 6605 6606 /* If BS is a copy on write image, it is initialized to 6607 the contents of the base image, which may not be zeroes. */ 6608 if (bdrv_cow_child(bs)) { 6609 return 0; 6610 } 6611 if (bs->drv->bdrv_has_zero_init) { 6612 return bs->drv->bdrv_has_zero_init(bs); 6613 } 6614 6615 filtered = bdrv_filter_bs(bs); 6616 if (filtered) { 6617 return bdrv_has_zero_init(filtered); 6618 } 6619 6620 /* safe default */ 6621 return 0; 6622 } 6623 6624 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs) 6625 { 6626 IO_CODE(); 6627 if (!(bs->open_flags & BDRV_O_UNMAP)) { 6628 return false; 6629 } 6630 6631 return bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP; 6632 } 6633 6634 void bdrv_get_backing_filename(BlockDriverState *bs, 6635 char *filename, int filename_size) 6636 { 6637 IO_CODE(); 6638 pstrcpy(filename, filename_size, bs->backing_file); 6639 } 6640 6641 int coroutine_fn bdrv_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) 6642 { 6643 int ret; 6644 BlockDriver *drv = bs->drv; 6645 IO_CODE(); 6646 assert_bdrv_graph_readable(); 6647 6648 /* if bs->drv == NULL, bs is closed, so there's nothing to do here */ 6649 if (!drv) { 6650 return -ENOMEDIUM; 6651 } 6652 if (!drv->bdrv_co_get_info) { 6653 BlockDriverState *filtered = bdrv_filter_bs(bs); 6654 if (filtered) { 6655 return bdrv_co_get_info(filtered, bdi); 6656 } 6657 return -ENOTSUP; 6658 } 6659 memset(bdi, 0, sizeof(*bdi)); 6660 ret = drv->bdrv_co_get_info(bs, bdi); 6661 if (bdi->subcluster_size == 0) { 6662 /* 6663 * If the driver left this unset, subclusters are not supported. 6664 * Then it is safe to treat each cluster as having only one subcluster. 6665 */ 6666 bdi->subcluster_size = bdi->cluster_size; 6667 } 6668 if (ret < 0) { 6669 return ret; 6670 } 6671 6672 if (bdi->cluster_size > BDRV_MAX_ALIGNMENT) { 6673 return -EINVAL; 6674 } 6675 6676 return 0; 6677 } 6678 6679 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs, 6680 Error **errp) 6681 { 6682 BlockDriver *drv = bs->drv; 6683 IO_CODE(); 6684 if (drv && drv->bdrv_get_specific_info) { 6685 return drv->bdrv_get_specific_info(bs, errp); 6686 } 6687 return NULL; 6688 } 6689 6690 BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs) 6691 { 6692 BlockDriver *drv = bs->drv; 6693 IO_CODE(); 6694 if (!drv || !drv->bdrv_get_specific_stats) { 6695 return NULL; 6696 } 6697 return drv->bdrv_get_specific_stats(bs); 6698 } 6699 6700 void coroutine_fn bdrv_co_debug_event(BlockDriverState *bs, BlkdebugEvent event) 6701 { 6702 IO_CODE(); 6703 assert_bdrv_graph_readable(); 6704 6705 if (!bs || !bs->drv || !bs->drv->bdrv_co_debug_event) { 6706 return; 6707 } 6708 6709 bs->drv->bdrv_co_debug_event(bs, event); 6710 } 6711 6712 static BlockDriverState * GRAPH_RDLOCK 6713 bdrv_find_debug_node(BlockDriverState *bs) 6714 { 6715 GLOBAL_STATE_CODE(); 6716 while (bs && bs->drv && !bs->drv->bdrv_debug_breakpoint) { 6717 bs = bdrv_primary_bs(bs); 6718 } 6719 6720 if (bs && bs->drv && bs->drv->bdrv_debug_breakpoint) { 6721 assert(bs->drv->bdrv_debug_remove_breakpoint); 6722 return bs; 6723 } 6724 6725 return NULL; 6726 } 6727 6728 int bdrv_debug_breakpoint(BlockDriverState *bs, const char *event, 6729 const char *tag) 6730 { 6731 GLOBAL_STATE_CODE(); 6732 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6733 6734 bs = bdrv_find_debug_node(bs); 6735 if (bs) { 6736 return bs->drv->bdrv_debug_breakpoint(bs, event, tag); 6737 } 6738 6739 return -ENOTSUP; 6740 } 6741 6742 int bdrv_debug_remove_breakpoint(BlockDriverState *bs, const char *tag) 6743 { 6744 GLOBAL_STATE_CODE(); 6745 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6746 6747 bs = bdrv_find_debug_node(bs); 6748 if (bs) { 6749 return bs->drv->bdrv_debug_remove_breakpoint(bs, tag); 6750 } 6751 6752 return -ENOTSUP; 6753 } 6754 6755 int bdrv_debug_resume(BlockDriverState *bs, const char *tag) 6756 { 6757 GLOBAL_STATE_CODE(); 6758 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6759 6760 while (bs && (!bs->drv || !bs->drv->bdrv_debug_resume)) { 6761 bs = bdrv_primary_bs(bs); 6762 } 6763 6764 if (bs && bs->drv && bs->drv->bdrv_debug_resume) { 6765 return bs->drv->bdrv_debug_resume(bs, tag); 6766 } 6767 6768 return -ENOTSUP; 6769 } 6770 6771 bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag) 6772 { 6773 GLOBAL_STATE_CODE(); 6774 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6775 6776 while (bs && bs->drv && !bs->drv->bdrv_debug_is_suspended) { 6777 bs = bdrv_primary_bs(bs); 6778 } 6779 6780 if (bs && bs->drv && bs->drv->bdrv_debug_is_suspended) { 6781 return bs->drv->bdrv_debug_is_suspended(bs, tag); 6782 } 6783 6784 return false; 6785 } 6786 6787 /* backing_file can either be relative, or absolute, or a protocol. If it is 6788 * relative, it must be relative to the chain. So, passing in bs->filename 6789 * from a BDS as backing_file should not be done, as that may be relative to 6790 * the CWD rather than the chain. */ 6791 BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, 6792 const char *backing_file) 6793 { 6794 char *filename_full = NULL; 6795 char *backing_file_full = NULL; 6796 char *filename_tmp = NULL; 6797 int is_protocol = 0; 6798 bool filenames_refreshed = false; 6799 BlockDriverState *curr_bs = NULL; 6800 BlockDriverState *retval = NULL; 6801 BlockDriverState *bs_below; 6802 6803 GLOBAL_STATE_CODE(); 6804 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6805 6806 if (!bs || !bs->drv || !backing_file) { 6807 return NULL; 6808 } 6809 6810 filename_full = g_malloc(PATH_MAX); 6811 backing_file_full = g_malloc(PATH_MAX); 6812 6813 is_protocol = path_has_protocol(backing_file); 6814 6815 /* 6816 * Being largely a legacy function, skip any filters here 6817 * (because filters do not have normal filenames, so they cannot 6818 * match anyway; and allowing json:{} filenames is a bit out of 6819 * scope). 6820 */ 6821 for (curr_bs = bdrv_skip_filters(bs); 6822 bdrv_cow_child(curr_bs) != NULL; 6823 curr_bs = bs_below) 6824 { 6825 bs_below = bdrv_backing_chain_next(curr_bs); 6826 6827 if (bdrv_backing_overridden(curr_bs)) { 6828 /* 6829 * If the backing file was overridden, we can only compare 6830 * directly against the backing node's filename. 6831 */ 6832 6833 if (!filenames_refreshed) { 6834 /* 6835 * This will automatically refresh all of the 6836 * filenames in the rest of the backing chain, so we 6837 * only need to do this once. 6838 */ 6839 bdrv_refresh_filename(bs_below); 6840 filenames_refreshed = true; 6841 } 6842 6843 if (strcmp(backing_file, bs_below->filename) == 0) { 6844 retval = bs_below; 6845 break; 6846 } 6847 } else if (is_protocol || path_has_protocol(curr_bs->backing_file)) { 6848 /* 6849 * If either of the filename paths is actually a protocol, then 6850 * compare unmodified paths; otherwise make paths relative. 6851 */ 6852 char *backing_file_full_ret; 6853 6854 if (strcmp(backing_file, curr_bs->backing_file) == 0) { 6855 retval = bs_below; 6856 break; 6857 } 6858 /* Also check against the full backing filename for the image */ 6859 backing_file_full_ret = bdrv_get_full_backing_filename(curr_bs, 6860 NULL); 6861 if (backing_file_full_ret) { 6862 bool equal = strcmp(backing_file, backing_file_full_ret) == 0; 6863 g_free(backing_file_full_ret); 6864 if (equal) { 6865 retval = bs_below; 6866 break; 6867 } 6868 } 6869 } else { 6870 /* If not an absolute filename path, make it relative to the current 6871 * image's filename path */ 6872 filename_tmp = bdrv_make_absolute_filename(curr_bs, backing_file, 6873 NULL); 6874 /* We are going to compare canonicalized absolute pathnames */ 6875 if (!filename_tmp || !realpath(filename_tmp, filename_full)) { 6876 g_free(filename_tmp); 6877 continue; 6878 } 6879 g_free(filename_tmp); 6880 6881 /* We need to make sure the backing filename we are comparing against 6882 * is relative to the current image filename (or absolute) */ 6883 filename_tmp = bdrv_get_full_backing_filename(curr_bs, NULL); 6884 if (!filename_tmp || !realpath(filename_tmp, backing_file_full)) { 6885 g_free(filename_tmp); 6886 continue; 6887 } 6888 g_free(filename_tmp); 6889 6890 if (strcmp(backing_file_full, filename_full) == 0) { 6891 retval = bs_below; 6892 break; 6893 } 6894 } 6895 } 6896 6897 g_free(filename_full); 6898 g_free(backing_file_full); 6899 return retval; 6900 } 6901 6902 void bdrv_init(void) 6903 { 6904 #ifdef CONFIG_BDRV_WHITELIST_TOOLS 6905 use_bdrv_whitelist = 1; 6906 #endif 6907 module_call_init(MODULE_INIT_BLOCK); 6908 } 6909 6910 void bdrv_init_with_whitelist(void) 6911 { 6912 use_bdrv_whitelist = 1; 6913 bdrv_init(); 6914 } 6915 6916 int bdrv_activate(BlockDriverState *bs, Error **errp) 6917 { 6918 BdrvChild *child, *parent; 6919 Error *local_err = NULL; 6920 int ret; 6921 BdrvDirtyBitmap *bm; 6922 6923 GLOBAL_STATE_CODE(); 6924 GRAPH_RDLOCK_GUARD_MAINLOOP(); 6925 6926 if (!bs->drv) { 6927 return -ENOMEDIUM; 6928 } 6929 6930 QLIST_FOREACH(child, &bs->children, next) { 6931 bdrv_activate(child->bs, &local_err); 6932 if (local_err) { 6933 error_propagate(errp, local_err); 6934 return -EINVAL; 6935 } 6936 } 6937 6938 /* 6939 * Update permissions, they may differ for inactive nodes. 6940 * 6941 * Note that the required permissions of inactive images are always a 6942 * subset of the permissions required after activating the image. This 6943 * allows us to just get the permissions upfront without restricting 6944 * bdrv_co_invalidate_cache(). 6945 * 6946 * It also means that in error cases, we don't have to try and revert to 6947 * the old permissions (which is an operation that could fail, too). We can 6948 * just keep the extended permissions for the next time that an activation 6949 * of the image is tried. 6950 */ 6951 if (bs->open_flags & BDRV_O_INACTIVE) { 6952 bs->open_flags &= ~BDRV_O_INACTIVE; 6953 ret = bdrv_refresh_perms(bs, NULL, errp); 6954 if (ret < 0) { 6955 bs->open_flags |= BDRV_O_INACTIVE; 6956 return ret; 6957 } 6958 6959 ret = bdrv_invalidate_cache(bs, errp); 6960 if (ret < 0) { 6961 bs->open_flags |= BDRV_O_INACTIVE; 6962 return ret; 6963 } 6964 6965 FOR_EACH_DIRTY_BITMAP(bs, bm) { 6966 bdrv_dirty_bitmap_skip_store(bm, false); 6967 } 6968 6969 ret = bdrv_refresh_total_sectors(bs, bs->total_sectors); 6970 if (ret < 0) { 6971 bs->open_flags |= BDRV_O_INACTIVE; 6972 error_setg_errno(errp, -ret, "Could not refresh total sector count"); 6973 return ret; 6974 } 6975 } 6976 6977 QLIST_FOREACH(parent, &bs->parents, next_parent) { 6978 if (parent->klass->activate) { 6979 parent->klass->activate(parent, &local_err); 6980 if (local_err) { 6981 bs->open_flags |= BDRV_O_INACTIVE; 6982 error_propagate(errp, local_err); 6983 return -EINVAL; 6984 } 6985 } 6986 } 6987 6988 return 0; 6989 } 6990 6991 int coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs, Error **errp) 6992 { 6993 Error *local_err = NULL; 6994 IO_CODE(); 6995 6996 assert(!(bs->open_flags & BDRV_O_INACTIVE)); 6997 assert_bdrv_graph_readable(); 6998 6999 if (bs->drv->bdrv_co_invalidate_cache) { 7000 bs->drv->bdrv_co_invalidate_cache(bs, &local_err); 7001 if (local_err) { 7002 error_propagate(errp, local_err); 7003 return -EINVAL; 7004 } 7005 } 7006 7007 return 0; 7008 } 7009 7010 void bdrv_activate_all(Error **errp) 7011 { 7012 BlockDriverState *bs; 7013 BdrvNextIterator it; 7014 7015 GLOBAL_STATE_CODE(); 7016 GRAPH_RDLOCK_GUARD_MAINLOOP(); 7017 7018 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { 7019 AioContext *aio_context = bdrv_get_aio_context(bs); 7020 int ret; 7021 7022 aio_context_acquire(aio_context); 7023 ret = bdrv_activate(bs, errp); 7024 aio_context_release(aio_context); 7025 if (ret < 0) { 7026 bdrv_next_cleanup(&it); 7027 return; 7028 } 7029 } 7030 } 7031 7032 static bool GRAPH_RDLOCK 7033 bdrv_has_bds_parent(BlockDriverState *bs, bool only_active) 7034 { 7035 BdrvChild *parent; 7036 GLOBAL_STATE_CODE(); 7037 7038 QLIST_FOREACH(parent, &bs->parents, next_parent) { 7039 if (parent->klass->parent_is_bds) { 7040 BlockDriverState *parent_bs = parent->opaque; 7041 if (!only_active || !(parent_bs->open_flags & BDRV_O_INACTIVE)) { 7042 return true; 7043 } 7044 } 7045 } 7046 7047 return false; 7048 } 7049 7050 static int GRAPH_RDLOCK bdrv_inactivate_recurse(BlockDriverState *bs) 7051 { 7052 BdrvChild *child, *parent; 7053 int ret; 7054 uint64_t cumulative_perms, cumulative_shared_perms; 7055 7056 GLOBAL_STATE_CODE(); 7057 7058 if (!bs->drv) { 7059 return -ENOMEDIUM; 7060 } 7061 7062 /* Make sure that we don't inactivate a child before its parent. 7063 * It will be covered by recursion from the yet active parent. */ 7064 if (bdrv_has_bds_parent(bs, true)) { 7065 return 0; 7066 } 7067 7068 assert(!(bs->open_flags & BDRV_O_INACTIVE)); 7069 7070 /* Inactivate this node */ 7071 if (bs->drv->bdrv_inactivate) { 7072 ret = bs->drv->bdrv_inactivate(bs); 7073 if (ret < 0) { 7074 return ret; 7075 } 7076 } 7077 7078 QLIST_FOREACH(parent, &bs->parents, next_parent) { 7079 if (parent->klass->inactivate) { 7080 ret = parent->klass->inactivate(parent); 7081 if (ret < 0) { 7082 return ret; 7083 } 7084 } 7085 } 7086 7087 bdrv_get_cumulative_perm(bs, &cumulative_perms, 7088 &cumulative_shared_perms); 7089 if (cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) { 7090 /* Our inactive parents still need write access. Inactivation failed. */ 7091 return -EPERM; 7092 } 7093 7094 bs->open_flags |= BDRV_O_INACTIVE; 7095 7096 /* 7097 * Update permissions, they may differ for inactive nodes. 7098 * We only tried to loosen restrictions, so errors are not fatal, ignore 7099 * them. 7100 */ 7101 bdrv_refresh_perms(bs, NULL, NULL); 7102 7103 /* Recursively inactivate children */ 7104 QLIST_FOREACH(child, &bs->children, next) { 7105 ret = bdrv_inactivate_recurse(child->bs); 7106 if (ret < 0) { 7107 return ret; 7108 } 7109 } 7110 7111 return 0; 7112 } 7113 7114 int bdrv_inactivate_all(void) 7115 { 7116 BlockDriverState *bs = NULL; 7117 BdrvNextIterator it; 7118 int ret = 0; 7119 GSList *aio_ctxs = NULL, *ctx; 7120 7121 GLOBAL_STATE_CODE(); 7122 GRAPH_RDLOCK_GUARD_MAINLOOP(); 7123 7124 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { 7125 AioContext *aio_context = bdrv_get_aio_context(bs); 7126 7127 if (!g_slist_find(aio_ctxs, aio_context)) { 7128 aio_ctxs = g_slist_prepend(aio_ctxs, aio_context); 7129 aio_context_acquire(aio_context); 7130 } 7131 } 7132 7133 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { 7134 /* Nodes with BDS parents are covered by recursion from the last 7135 * parent that gets inactivated. Don't inactivate them a second 7136 * time if that has already happened. */ 7137 if (bdrv_has_bds_parent(bs, false)) { 7138 continue; 7139 } 7140 ret = bdrv_inactivate_recurse(bs); 7141 if (ret < 0) { 7142 bdrv_next_cleanup(&it); 7143 goto out; 7144 } 7145 } 7146 7147 out: 7148 for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) { 7149 AioContext *aio_context = ctx->data; 7150 aio_context_release(aio_context); 7151 } 7152 g_slist_free(aio_ctxs); 7153 7154 return ret; 7155 } 7156 7157 /**************************************************************/ 7158 /* removable device support */ 7159 7160 /** 7161 * Return TRUE if the media is present 7162 */ 7163 bool coroutine_fn bdrv_co_is_inserted(BlockDriverState *bs) 7164 { 7165 BlockDriver *drv = bs->drv; 7166 BdrvChild *child; 7167 IO_CODE(); 7168 assert_bdrv_graph_readable(); 7169 7170 if (!drv) { 7171 return false; 7172 } 7173 if (drv->bdrv_co_is_inserted) { 7174 return drv->bdrv_co_is_inserted(bs); 7175 } 7176 QLIST_FOREACH(child, &bs->children, next) { 7177 if (!bdrv_co_is_inserted(child->bs)) { 7178 return false; 7179 } 7180 } 7181 return true; 7182 } 7183 7184 /** 7185 * If eject_flag is TRUE, eject the media. Otherwise, close the tray 7186 */ 7187 void coroutine_fn bdrv_co_eject(BlockDriverState *bs, bool eject_flag) 7188 { 7189 BlockDriver *drv = bs->drv; 7190 IO_CODE(); 7191 assert_bdrv_graph_readable(); 7192 7193 if (drv && drv->bdrv_co_eject) { 7194 drv->bdrv_co_eject(bs, eject_flag); 7195 } 7196 } 7197 7198 /** 7199 * Lock or unlock the media (if it is locked, the user won't be able 7200 * to eject it manually). 7201 */ 7202 void coroutine_fn bdrv_co_lock_medium(BlockDriverState *bs, bool locked) 7203 { 7204 BlockDriver *drv = bs->drv; 7205 IO_CODE(); 7206 assert_bdrv_graph_readable(); 7207 trace_bdrv_lock_medium(bs, locked); 7208 7209 if (drv && drv->bdrv_co_lock_medium) { 7210 drv->bdrv_co_lock_medium(bs, locked); 7211 } 7212 } 7213 7214 /* Get a reference to bs */ 7215 void bdrv_ref(BlockDriverState *bs) 7216 { 7217 GLOBAL_STATE_CODE(); 7218 bs->refcnt++; 7219 } 7220 7221 /* Release a previously grabbed reference to bs. 7222 * If after releasing, reference count is zero, the BlockDriverState is 7223 * deleted. */ 7224 void bdrv_unref(BlockDriverState *bs) 7225 { 7226 GLOBAL_STATE_CODE(); 7227 if (!bs) { 7228 return; 7229 } 7230 assert(bs->refcnt > 0); 7231 if (--bs->refcnt == 0) { 7232 bdrv_delete(bs); 7233 } 7234 } 7235 7236 /* 7237 * Release a BlockDriverState reference while holding the graph write lock. 7238 * 7239 * Calling bdrv_unref() directly is forbidden while holding the graph lock 7240 * because bdrv_close() both involves polling and taking the graph lock 7241 * internally. bdrv_schedule_unref() instead delays decreasing the refcount and 7242 * possibly closing @bs until the graph lock is released. 7243 */ 7244 void bdrv_schedule_unref(BlockDriverState *bs) 7245 { 7246 if (!bs) { 7247 return; 7248 } 7249 aio_bh_schedule_oneshot(qemu_get_aio_context(), 7250 (QEMUBHFunc *) bdrv_unref, bs); 7251 } 7252 7253 struct BdrvOpBlocker { 7254 Error *reason; 7255 QLIST_ENTRY(BdrvOpBlocker) list; 7256 }; 7257 7258 bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp) 7259 { 7260 BdrvOpBlocker *blocker; 7261 GLOBAL_STATE_CODE(); 7262 7263 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); 7264 if (!QLIST_EMPTY(&bs->op_blockers[op])) { 7265 blocker = QLIST_FIRST(&bs->op_blockers[op]); 7266 error_propagate_prepend(errp, error_copy(blocker->reason), 7267 "Node '%s' is busy: ", 7268 bdrv_get_device_or_node_name(bs)); 7269 return true; 7270 } 7271 return false; 7272 } 7273 7274 void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason) 7275 { 7276 BdrvOpBlocker *blocker; 7277 GLOBAL_STATE_CODE(); 7278 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); 7279 7280 blocker = g_new0(BdrvOpBlocker, 1); 7281 blocker->reason = reason; 7282 QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list); 7283 } 7284 7285 void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason) 7286 { 7287 BdrvOpBlocker *blocker, *next; 7288 GLOBAL_STATE_CODE(); 7289 assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX); 7290 QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) { 7291 if (blocker->reason == reason) { 7292 QLIST_REMOVE(blocker, list); 7293 g_free(blocker); 7294 } 7295 } 7296 } 7297 7298 void bdrv_op_block_all(BlockDriverState *bs, Error *reason) 7299 { 7300 int i; 7301 GLOBAL_STATE_CODE(); 7302 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 7303 bdrv_op_block(bs, i, reason); 7304 } 7305 } 7306 7307 void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason) 7308 { 7309 int i; 7310 GLOBAL_STATE_CODE(); 7311 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 7312 bdrv_op_unblock(bs, i, reason); 7313 } 7314 } 7315 7316 bool bdrv_op_blocker_is_empty(BlockDriverState *bs) 7317 { 7318 int i; 7319 GLOBAL_STATE_CODE(); 7320 for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) { 7321 if (!QLIST_EMPTY(&bs->op_blockers[i])) { 7322 return false; 7323 } 7324 } 7325 return true; 7326 } 7327 7328 /* 7329 * Must not be called while holding the lock of an AioContext other than the 7330 * current one. 7331 */ 7332 void bdrv_img_create(const char *filename, const char *fmt, 7333 const char *base_filename, const char *base_fmt, 7334 char *options, uint64_t img_size, int flags, bool quiet, 7335 Error **errp) 7336 { 7337 QemuOptsList *create_opts = NULL; 7338 QemuOpts *opts = NULL; 7339 const char *backing_fmt, *backing_file; 7340 int64_t size; 7341 BlockDriver *drv, *proto_drv; 7342 Error *local_err = NULL; 7343 int ret = 0; 7344 7345 GLOBAL_STATE_CODE(); 7346 7347 /* Find driver and parse its options */ 7348 drv = bdrv_find_format(fmt); 7349 if (!drv) { 7350 error_setg(errp, "Unknown file format '%s'", fmt); 7351 return; 7352 } 7353 7354 proto_drv = bdrv_find_protocol(filename, true, errp); 7355 if (!proto_drv) { 7356 return; 7357 } 7358 7359 if (!drv->create_opts) { 7360 error_setg(errp, "Format driver '%s' does not support image creation", 7361 drv->format_name); 7362 return; 7363 } 7364 7365 if (!proto_drv->create_opts) { 7366 error_setg(errp, "Protocol driver '%s' does not support image creation", 7367 proto_drv->format_name); 7368 return; 7369 } 7370 7371 aio_context_acquire(qemu_get_aio_context()); 7372 7373 /* Create parameter list */ 7374 create_opts = qemu_opts_append(create_opts, drv->create_opts); 7375 create_opts = qemu_opts_append(create_opts, proto_drv->create_opts); 7376 7377 opts = qemu_opts_create(create_opts, NULL, 0, &error_abort); 7378 7379 /* Parse -o options */ 7380 if (options) { 7381 if (!qemu_opts_do_parse(opts, options, NULL, errp)) { 7382 goto out; 7383 } 7384 } 7385 7386 if (!qemu_opt_get(opts, BLOCK_OPT_SIZE)) { 7387 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, img_size, &error_abort); 7388 } else if (img_size != UINT64_C(-1)) { 7389 error_setg(errp, "The image size must be specified only once"); 7390 goto out; 7391 } 7392 7393 if (base_filename) { 7394 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FILE, base_filename, 7395 NULL)) { 7396 error_setg(errp, "Backing file not supported for file format '%s'", 7397 fmt); 7398 goto out; 7399 } 7400 } 7401 7402 if (base_fmt) { 7403 if (!qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, base_fmt, NULL)) { 7404 error_setg(errp, "Backing file format not supported for file " 7405 "format '%s'", fmt); 7406 goto out; 7407 } 7408 } 7409 7410 backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE); 7411 if (backing_file) { 7412 if (!strcmp(filename, backing_file)) { 7413 error_setg(errp, "Error: Trying to create an image with the " 7414 "same filename as the backing file"); 7415 goto out; 7416 } 7417 if (backing_file[0] == '\0') { 7418 error_setg(errp, "Expected backing file name, got empty string"); 7419 goto out; 7420 } 7421 } 7422 7423 backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT); 7424 7425 /* The size for the image must always be specified, unless we have a backing 7426 * file and we have not been forbidden from opening it. */ 7427 size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, img_size); 7428 if (backing_file && !(flags & BDRV_O_NO_BACKING)) { 7429 BlockDriverState *bs; 7430 char *full_backing; 7431 int back_flags; 7432 QDict *backing_options = NULL; 7433 7434 full_backing = 7435 bdrv_get_full_backing_filename_from_filename(filename, backing_file, 7436 &local_err); 7437 if (local_err) { 7438 goto out; 7439 } 7440 assert(full_backing); 7441 7442 /* 7443 * No need to do I/O here, which allows us to open encrypted 7444 * backing images without needing the secret 7445 */ 7446 back_flags = flags; 7447 back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING); 7448 back_flags |= BDRV_O_NO_IO; 7449 7450 backing_options = qdict_new(); 7451 if (backing_fmt) { 7452 qdict_put_str(backing_options, "driver", backing_fmt); 7453 } 7454 qdict_put_bool(backing_options, BDRV_OPT_FORCE_SHARE, true); 7455 7456 bs = bdrv_open(full_backing, NULL, backing_options, back_flags, 7457 &local_err); 7458 g_free(full_backing); 7459 if (!bs) { 7460 error_append_hint(&local_err, "Could not open backing image.\n"); 7461 goto out; 7462 } else { 7463 if (!backing_fmt) { 7464 error_setg(&local_err, 7465 "Backing file specified without backing format"); 7466 error_append_hint(&local_err, "Detected format of %s.\n", 7467 bs->drv->format_name); 7468 goto out; 7469 } 7470 if (size == -1) { 7471 /* Opened BS, have no size */ 7472 size = bdrv_getlength(bs); 7473 if (size < 0) { 7474 error_setg_errno(errp, -size, "Could not get size of '%s'", 7475 backing_file); 7476 bdrv_unref(bs); 7477 goto out; 7478 } 7479 qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort); 7480 } 7481 bdrv_unref(bs); 7482 } 7483 /* (backing_file && !(flags & BDRV_O_NO_BACKING)) */ 7484 } else if (backing_file && !backing_fmt) { 7485 error_setg(&local_err, 7486 "Backing file specified without backing format"); 7487 goto out; 7488 } 7489 7490 if (size == -1) { 7491 error_setg(errp, "Image creation needs a size parameter"); 7492 goto out; 7493 } 7494 7495 if (!quiet) { 7496 printf("Formatting '%s', fmt=%s ", filename, fmt); 7497 qemu_opts_print(opts, " "); 7498 puts(""); 7499 fflush(stdout); 7500 } 7501 7502 ret = bdrv_create(drv, filename, opts, &local_err); 7503 7504 if (ret == -EFBIG) { 7505 /* This is generally a better message than whatever the driver would 7506 * deliver (especially because of the cluster_size_hint), since that 7507 * is most probably not much different from "image too large". */ 7508 const char *cluster_size_hint = ""; 7509 if (qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE, 0)) { 7510 cluster_size_hint = " (try using a larger cluster size)"; 7511 } 7512 error_setg(errp, "The image size is too large for file format '%s'" 7513 "%s", fmt, cluster_size_hint); 7514 error_free(local_err); 7515 local_err = NULL; 7516 } 7517 7518 out: 7519 qemu_opts_del(opts); 7520 qemu_opts_free(create_opts); 7521 error_propagate(errp, local_err); 7522 aio_context_release(qemu_get_aio_context()); 7523 } 7524 7525 AioContext *bdrv_get_aio_context(BlockDriverState *bs) 7526 { 7527 IO_CODE(); 7528 return bs ? bs->aio_context : qemu_get_aio_context(); 7529 } 7530 7531 AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs) 7532 { 7533 Coroutine *self = qemu_coroutine_self(); 7534 AioContext *old_ctx = qemu_coroutine_get_aio_context(self); 7535 AioContext *new_ctx; 7536 IO_CODE(); 7537 7538 /* 7539 * Increase bs->in_flight to ensure that this operation is completed before 7540 * moving the node to a different AioContext. Read new_ctx only afterwards. 7541 */ 7542 bdrv_inc_in_flight(bs); 7543 7544 new_ctx = bdrv_get_aio_context(bs); 7545 aio_co_reschedule_self(new_ctx); 7546 return old_ctx; 7547 } 7548 7549 void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx) 7550 { 7551 IO_CODE(); 7552 aio_co_reschedule_self(old_ctx); 7553 bdrv_dec_in_flight(bs); 7554 } 7555 7556 void coroutine_fn bdrv_co_lock(BlockDriverState *bs) 7557 { 7558 AioContext *ctx = bdrv_get_aio_context(bs); 7559 7560 /* In the main thread, bs->aio_context won't change concurrently */ 7561 assert(qemu_get_current_aio_context() == qemu_get_aio_context()); 7562 7563 /* 7564 * We're in coroutine context, so we already hold the lock of the main 7565 * loop AioContext. Don't lock it twice to avoid deadlocks. 7566 */ 7567 assert(qemu_in_coroutine()); 7568 if (ctx != qemu_get_aio_context()) { 7569 aio_context_acquire(ctx); 7570 } 7571 } 7572 7573 void coroutine_fn bdrv_co_unlock(BlockDriverState *bs) 7574 { 7575 AioContext *ctx = bdrv_get_aio_context(bs); 7576 7577 assert(qemu_in_coroutine()); 7578 if (ctx != qemu_get_aio_context()) { 7579 aio_context_release(ctx); 7580 } 7581 } 7582 7583 static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban) 7584 { 7585 GLOBAL_STATE_CODE(); 7586 QLIST_REMOVE(ban, list); 7587 g_free(ban); 7588 } 7589 7590 static void bdrv_detach_aio_context(BlockDriverState *bs) 7591 { 7592 BdrvAioNotifier *baf, *baf_tmp; 7593 7594 assert(!bs->walking_aio_notifiers); 7595 GLOBAL_STATE_CODE(); 7596 bs->walking_aio_notifiers = true; 7597 QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) { 7598 if (baf->deleted) { 7599 bdrv_do_remove_aio_context_notifier(baf); 7600 } else { 7601 baf->detach_aio_context(baf->opaque); 7602 } 7603 } 7604 /* Never mind iterating again to check for ->deleted. bdrv_close() will 7605 * remove remaining aio notifiers if we aren't called again. 7606 */ 7607 bs->walking_aio_notifiers = false; 7608 7609 if (bs->drv && bs->drv->bdrv_detach_aio_context) { 7610 bs->drv->bdrv_detach_aio_context(bs); 7611 } 7612 7613 bs->aio_context = NULL; 7614 } 7615 7616 static void bdrv_attach_aio_context(BlockDriverState *bs, 7617 AioContext *new_context) 7618 { 7619 BdrvAioNotifier *ban, *ban_tmp; 7620 GLOBAL_STATE_CODE(); 7621 7622 bs->aio_context = new_context; 7623 7624 if (bs->drv && bs->drv->bdrv_attach_aio_context) { 7625 bs->drv->bdrv_attach_aio_context(bs, new_context); 7626 } 7627 7628 assert(!bs->walking_aio_notifiers); 7629 bs->walking_aio_notifiers = true; 7630 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_tmp) { 7631 if (ban->deleted) { 7632 bdrv_do_remove_aio_context_notifier(ban); 7633 } else { 7634 ban->attached_aio_context(new_context, ban->opaque); 7635 } 7636 } 7637 bs->walking_aio_notifiers = false; 7638 } 7639 7640 typedef struct BdrvStateSetAioContext { 7641 AioContext *new_ctx; 7642 BlockDriverState *bs; 7643 } BdrvStateSetAioContext; 7644 7645 static bool bdrv_parent_change_aio_context(BdrvChild *c, AioContext *ctx, 7646 GHashTable *visited, 7647 Transaction *tran, 7648 Error **errp) 7649 { 7650 GLOBAL_STATE_CODE(); 7651 if (g_hash_table_contains(visited, c)) { 7652 return true; 7653 } 7654 g_hash_table_add(visited, c); 7655 7656 /* 7657 * A BdrvChildClass that doesn't handle AioContext changes cannot 7658 * tolerate any AioContext changes 7659 */ 7660 if (!c->klass->change_aio_ctx) { 7661 char *user = bdrv_child_user_desc(c); 7662 error_setg(errp, "Changing iothreads is not supported by %s", user); 7663 g_free(user); 7664 return false; 7665 } 7666 if (!c->klass->change_aio_ctx(c, ctx, visited, tran, errp)) { 7667 assert(!errp || *errp); 7668 return false; 7669 } 7670 return true; 7671 } 7672 7673 bool bdrv_child_change_aio_context(BdrvChild *c, AioContext *ctx, 7674 GHashTable *visited, Transaction *tran, 7675 Error **errp) 7676 { 7677 GLOBAL_STATE_CODE(); 7678 if (g_hash_table_contains(visited, c)) { 7679 return true; 7680 } 7681 g_hash_table_add(visited, c); 7682 return bdrv_change_aio_context(c->bs, ctx, visited, tran, errp); 7683 } 7684 7685 static void bdrv_set_aio_context_clean(void *opaque) 7686 { 7687 BdrvStateSetAioContext *state = (BdrvStateSetAioContext *) opaque; 7688 BlockDriverState *bs = (BlockDriverState *) state->bs; 7689 7690 /* Paired with bdrv_drained_begin in bdrv_change_aio_context() */ 7691 bdrv_drained_end(bs); 7692 7693 g_free(state); 7694 } 7695 7696 static void bdrv_set_aio_context_commit(void *opaque) 7697 { 7698 BdrvStateSetAioContext *state = (BdrvStateSetAioContext *) opaque; 7699 BlockDriverState *bs = (BlockDriverState *) state->bs; 7700 AioContext *new_context = state->new_ctx; 7701 AioContext *old_context = bdrv_get_aio_context(bs); 7702 7703 /* 7704 * Take the old AioContex when detaching it from bs. 7705 * At this point, new_context lock is already acquired, and we are now 7706 * also taking old_context. This is safe as long as bdrv_detach_aio_context 7707 * does not call AIO_POLL_WHILE(). 7708 */ 7709 if (old_context != qemu_get_aio_context()) { 7710 aio_context_acquire(old_context); 7711 } 7712 bdrv_detach_aio_context(bs); 7713 if (old_context != qemu_get_aio_context()) { 7714 aio_context_release(old_context); 7715 } 7716 bdrv_attach_aio_context(bs, new_context); 7717 } 7718 7719 static TransactionActionDrv set_aio_context = { 7720 .commit = bdrv_set_aio_context_commit, 7721 .clean = bdrv_set_aio_context_clean, 7722 }; 7723 7724 /* 7725 * Changes the AioContext used for fd handlers, timers, and BHs by this 7726 * BlockDriverState and all its children and parents. 7727 * 7728 * Must be called from the main AioContext. 7729 * 7730 * The caller must own the AioContext lock for the old AioContext of bs, but it 7731 * must not own the AioContext lock for new_context (unless new_context is the 7732 * same as the current context of bs). 7733 * 7734 * @visited will accumulate all visited BdrvChild objects. The caller is 7735 * responsible for freeing the list afterwards. 7736 */ 7737 static bool bdrv_change_aio_context(BlockDriverState *bs, AioContext *ctx, 7738 GHashTable *visited, Transaction *tran, 7739 Error **errp) 7740 { 7741 BdrvChild *c; 7742 BdrvStateSetAioContext *state; 7743 7744 GLOBAL_STATE_CODE(); 7745 7746 if (bdrv_get_aio_context(bs) == ctx) { 7747 return true; 7748 } 7749 7750 bdrv_graph_rdlock_main_loop(); 7751 QLIST_FOREACH(c, &bs->parents, next_parent) { 7752 if (!bdrv_parent_change_aio_context(c, ctx, visited, tran, errp)) { 7753 bdrv_graph_rdunlock_main_loop(); 7754 return false; 7755 } 7756 } 7757 7758 QLIST_FOREACH(c, &bs->children, next) { 7759 if (!bdrv_child_change_aio_context(c, ctx, visited, tran, errp)) { 7760 bdrv_graph_rdunlock_main_loop(); 7761 return false; 7762 } 7763 } 7764 bdrv_graph_rdunlock_main_loop(); 7765 7766 state = g_new(BdrvStateSetAioContext, 1); 7767 *state = (BdrvStateSetAioContext) { 7768 .new_ctx = ctx, 7769 .bs = bs, 7770 }; 7771 7772 /* Paired with bdrv_drained_end in bdrv_set_aio_context_clean() */ 7773 bdrv_drained_begin(bs); 7774 7775 tran_add(tran, &set_aio_context, state); 7776 7777 return true; 7778 } 7779 7780 /* 7781 * Change bs's and recursively all of its parents' and children's AioContext 7782 * to the given new context, returning an error if that isn't possible. 7783 * 7784 * If ignore_child is not NULL, that child (and its subgraph) will not 7785 * be touched. 7786 * 7787 * This function still requires the caller to take the bs current 7788 * AioContext lock, otherwise draining will fail since AIO_WAIT_WHILE 7789 * assumes the lock is always held if bs is in another AioContext. 7790 * For the same reason, it temporarily also holds the new AioContext, since 7791 * bdrv_drained_end calls BDRV_POLL_WHILE that assumes the lock is taken too. 7792 * Therefore the new AioContext lock must not be taken by the caller. 7793 */ 7794 int bdrv_try_change_aio_context(BlockDriverState *bs, AioContext *ctx, 7795 BdrvChild *ignore_child, Error **errp) 7796 { 7797 Transaction *tran; 7798 GHashTable *visited; 7799 int ret; 7800 AioContext *old_context = bdrv_get_aio_context(bs); 7801 GLOBAL_STATE_CODE(); 7802 7803 /* 7804 * Recursion phase: go through all nodes of the graph. 7805 * Take care of checking that all nodes support changing AioContext 7806 * and drain them, building a linear list of callbacks to run if everything 7807 * is successful (the transaction itself). 7808 */ 7809 tran = tran_new(); 7810 visited = g_hash_table_new(NULL, NULL); 7811 if (ignore_child) { 7812 g_hash_table_add(visited, ignore_child); 7813 } 7814 ret = bdrv_change_aio_context(bs, ctx, visited, tran, errp); 7815 g_hash_table_destroy(visited); 7816 7817 /* 7818 * Linear phase: go through all callbacks collected in the transaction. 7819 * Run all callbacks collected in the recursion to switch all nodes 7820 * AioContext lock (transaction commit), or undo all changes done in the 7821 * recursion (transaction abort). 7822 */ 7823 7824 if (!ret) { 7825 /* Just run clean() callbacks. No AioContext changed. */ 7826 tran_abort(tran); 7827 return -EPERM; 7828 } 7829 7830 /* 7831 * Release old AioContext, it won't be needed anymore, as all 7832 * bdrv_drained_begin() have been called already. 7833 */ 7834 if (qemu_get_aio_context() != old_context) { 7835 aio_context_release(old_context); 7836 } 7837 7838 /* 7839 * Acquire new AioContext since bdrv_drained_end() is going to be called 7840 * after we switched all nodes in the new AioContext, and the function 7841 * assumes that the lock of the bs is always taken. 7842 */ 7843 if (qemu_get_aio_context() != ctx) { 7844 aio_context_acquire(ctx); 7845 } 7846 7847 tran_commit(tran); 7848 7849 if (qemu_get_aio_context() != ctx) { 7850 aio_context_release(ctx); 7851 } 7852 7853 /* Re-acquire the old AioContext, since the caller takes and releases it. */ 7854 if (qemu_get_aio_context() != old_context) { 7855 aio_context_acquire(old_context); 7856 } 7857 7858 return 0; 7859 } 7860 7861 void bdrv_add_aio_context_notifier(BlockDriverState *bs, 7862 void (*attached_aio_context)(AioContext *new_context, void *opaque), 7863 void (*detach_aio_context)(void *opaque), void *opaque) 7864 { 7865 BdrvAioNotifier *ban = g_new(BdrvAioNotifier, 1); 7866 *ban = (BdrvAioNotifier){ 7867 .attached_aio_context = attached_aio_context, 7868 .detach_aio_context = detach_aio_context, 7869 .opaque = opaque 7870 }; 7871 GLOBAL_STATE_CODE(); 7872 7873 QLIST_INSERT_HEAD(&bs->aio_notifiers, ban, list); 7874 } 7875 7876 void bdrv_remove_aio_context_notifier(BlockDriverState *bs, 7877 void (*attached_aio_context)(AioContext *, 7878 void *), 7879 void (*detach_aio_context)(void *), 7880 void *opaque) 7881 { 7882 BdrvAioNotifier *ban, *ban_next; 7883 GLOBAL_STATE_CODE(); 7884 7885 QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) { 7886 if (ban->attached_aio_context == attached_aio_context && 7887 ban->detach_aio_context == detach_aio_context && 7888 ban->opaque == opaque && 7889 ban->deleted == false) 7890 { 7891 if (bs->walking_aio_notifiers) { 7892 ban->deleted = true; 7893 } else { 7894 bdrv_do_remove_aio_context_notifier(ban); 7895 } 7896 return; 7897 } 7898 } 7899 7900 abort(); 7901 } 7902 7903 int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts, 7904 BlockDriverAmendStatusCB *status_cb, void *cb_opaque, 7905 bool force, 7906 Error **errp) 7907 { 7908 GLOBAL_STATE_CODE(); 7909 if (!bs->drv) { 7910 error_setg(errp, "Node is ejected"); 7911 return -ENOMEDIUM; 7912 } 7913 if (!bs->drv->bdrv_amend_options) { 7914 error_setg(errp, "Block driver '%s' does not support option amendment", 7915 bs->drv->format_name); 7916 return -ENOTSUP; 7917 } 7918 return bs->drv->bdrv_amend_options(bs, opts, status_cb, 7919 cb_opaque, force, errp); 7920 } 7921 7922 /* 7923 * This function checks whether the given @to_replace is allowed to be 7924 * replaced by a node that always shows the same data as @bs. This is 7925 * used for example to verify whether the mirror job can replace 7926 * @to_replace by the target mirrored from @bs. 7927 * To be replaceable, @bs and @to_replace may either be guaranteed to 7928 * always show the same data (because they are only connected through 7929 * filters), or some driver may allow replacing one of its children 7930 * because it can guarantee that this child's data is not visible at 7931 * all (for example, for dissenting quorum children that have no other 7932 * parents). 7933 */ 7934 bool bdrv_recurse_can_replace(BlockDriverState *bs, 7935 BlockDriverState *to_replace) 7936 { 7937 BlockDriverState *filtered; 7938 7939 GLOBAL_STATE_CODE(); 7940 7941 if (!bs || !bs->drv) { 7942 return false; 7943 } 7944 7945 if (bs == to_replace) { 7946 return true; 7947 } 7948 7949 /* See what the driver can do */ 7950 if (bs->drv->bdrv_recurse_can_replace) { 7951 return bs->drv->bdrv_recurse_can_replace(bs, to_replace); 7952 } 7953 7954 /* For filters without an own implementation, we can recurse on our own */ 7955 filtered = bdrv_filter_bs(bs); 7956 if (filtered) { 7957 return bdrv_recurse_can_replace(filtered, to_replace); 7958 } 7959 7960 /* Safe default */ 7961 return false; 7962 } 7963 7964 /* 7965 * Check whether the given @node_name can be replaced by a node that 7966 * has the same data as @parent_bs. If so, return @node_name's BDS; 7967 * NULL otherwise. 7968 * 7969 * @node_name must be a (recursive) *child of @parent_bs (or this 7970 * function will return NULL). 7971 * 7972 * The result (whether the node can be replaced or not) is only valid 7973 * for as long as no graph or permission changes occur. 7974 */ 7975 BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs, 7976 const char *node_name, Error **errp) 7977 { 7978 BlockDriverState *to_replace_bs = bdrv_find_node(node_name); 7979 AioContext *aio_context; 7980 7981 GLOBAL_STATE_CODE(); 7982 7983 if (!to_replace_bs) { 7984 error_setg(errp, "Failed to find node with node-name='%s'", node_name); 7985 return NULL; 7986 } 7987 7988 aio_context = bdrv_get_aio_context(to_replace_bs); 7989 aio_context_acquire(aio_context); 7990 7991 if (bdrv_op_is_blocked(to_replace_bs, BLOCK_OP_TYPE_REPLACE, errp)) { 7992 to_replace_bs = NULL; 7993 goto out; 7994 } 7995 7996 /* We don't want arbitrary node of the BDS chain to be replaced only the top 7997 * most non filter in order to prevent data corruption. 7998 * Another benefit is that this tests exclude backing files which are 7999 * blocked by the backing blockers. 8000 */ 8001 if (!bdrv_recurse_can_replace(parent_bs, to_replace_bs)) { 8002 error_setg(errp, "Cannot replace '%s' by a node mirrored from '%s', " 8003 "because it cannot be guaranteed that doing so would not " 8004 "lead to an abrupt change of visible data", 8005 node_name, parent_bs->node_name); 8006 to_replace_bs = NULL; 8007 goto out; 8008 } 8009 8010 out: 8011 aio_context_release(aio_context); 8012 return to_replace_bs; 8013 } 8014 8015 /** 8016 * Iterates through the list of runtime option keys that are said to 8017 * be "strong" for a BDS. An option is called "strong" if it changes 8018 * a BDS's data. For example, the null block driver's "size" and 8019 * "read-zeroes" options are strong, but its "latency-ns" option is 8020 * not. 8021 * 8022 * If a key returned by this function ends with a dot, all options 8023 * starting with that prefix are strong. 8024 */ 8025 static const char *const *strong_options(BlockDriverState *bs, 8026 const char *const *curopt) 8027 { 8028 static const char *const global_options[] = { 8029 "driver", "filename", NULL 8030 }; 8031 8032 if (!curopt) { 8033 return &global_options[0]; 8034 } 8035 8036 curopt++; 8037 if (curopt == &global_options[ARRAY_SIZE(global_options) - 1] && bs->drv) { 8038 curopt = bs->drv->strong_runtime_opts; 8039 } 8040 8041 return (curopt && *curopt) ? curopt : NULL; 8042 } 8043 8044 /** 8045 * Copies all strong runtime options from bs->options to the given 8046 * QDict. The set of strong option keys is determined by invoking 8047 * strong_options(). 8048 * 8049 * Returns true iff any strong option was present in bs->options (and 8050 * thus copied to the target QDict) with the exception of "filename" 8051 * and "driver". The caller is expected to use this value to decide 8052 * whether the existence of strong options prevents the generation of 8053 * a plain filename. 8054 */ 8055 static bool append_strong_runtime_options(QDict *d, BlockDriverState *bs) 8056 { 8057 bool found_any = false; 8058 const char *const *option_name = NULL; 8059 8060 if (!bs->drv) { 8061 return false; 8062 } 8063 8064 while ((option_name = strong_options(bs, option_name))) { 8065 bool option_given = false; 8066 8067 assert(strlen(*option_name) > 0); 8068 if ((*option_name)[strlen(*option_name) - 1] != '.') { 8069 QObject *entry = qdict_get(bs->options, *option_name); 8070 if (!entry) { 8071 continue; 8072 } 8073 8074 qdict_put_obj(d, *option_name, qobject_ref(entry)); 8075 option_given = true; 8076 } else { 8077 const QDictEntry *entry; 8078 for (entry = qdict_first(bs->options); entry; 8079 entry = qdict_next(bs->options, entry)) 8080 { 8081 if (strstart(qdict_entry_key(entry), *option_name, NULL)) { 8082 qdict_put_obj(d, qdict_entry_key(entry), 8083 qobject_ref(qdict_entry_value(entry))); 8084 option_given = true; 8085 } 8086 } 8087 } 8088 8089 /* While "driver" and "filename" need to be included in a JSON filename, 8090 * their existence does not prohibit generation of a plain filename. */ 8091 if (!found_any && option_given && 8092 strcmp(*option_name, "driver") && strcmp(*option_name, "filename")) 8093 { 8094 found_any = true; 8095 } 8096 } 8097 8098 if (!qdict_haskey(d, "driver")) { 8099 /* Drivers created with bdrv_new_open_driver() may not have a 8100 * @driver option. Add it here. */ 8101 qdict_put_str(d, "driver", bs->drv->format_name); 8102 } 8103 8104 return found_any; 8105 } 8106 8107 /* Note: This function may return false positives; it may return true 8108 * even if opening the backing file specified by bs's image header 8109 * would result in exactly bs->backing. */ 8110 static bool bdrv_backing_overridden(BlockDriverState *bs) 8111 { 8112 GLOBAL_STATE_CODE(); 8113 if (bs->backing) { 8114 return strcmp(bs->auto_backing_file, 8115 bs->backing->bs->filename); 8116 } else { 8117 /* No backing BDS, so if the image header reports any backing 8118 * file, it must have been suppressed */ 8119 return bs->auto_backing_file[0] != '\0'; 8120 } 8121 } 8122 8123 /* Updates the following BDS fields: 8124 * - exact_filename: A filename which may be used for opening a block device 8125 * which (mostly) equals the given BDS (even without any 8126 * other options; so reading and writing must return the same 8127 * results, but caching etc. may be different) 8128 * - full_open_options: Options which, when given when opening a block device 8129 * (without a filename), result in a BDS (mostly) 8130 * equalling the given one 8131 * - filename: If exact_filename is set, it is copied here. Otherwise, 8132 * full_open_options is converted to a JSON object, prefixed with 8133 * "json:" (for use through the JSON pseudo protocol) and put here. 8134 */ 8135 void bdrv_refresh_filename(BlockDriverState *bs) 8136 { 8137 BlockDriver *drv = bs->drv; 8138 BdrvChild *child; 8139 BlockDriverState *primary_child_bs; 8140 QDict *opts; 8141 bool backing_overridden; 8142 bool generate_json_filename; /* Whether our default implementation should 8143 fill exact_filename (false) or not (true) */ 8144 8145 GLOBAL_STATE_CODE(); 8146 8147 if (!drv) { 8148 return; 8149 } 8150 8151 /* This BDS's file name may depend on any of its children's file names, so 8152 * refresh those first */ 8153 QLIST_FOREACH(child, &bs->children, next) { 8154 bdrv_refresh_filename(child->bs); 8155 } 8156 8157 if (bs->implicit) { 8158 /* For implicit nodes, just copy everything from the single child */ 8159 child = QLIST_FIRST(&bs->children); 8160 assert(QLIST_NEXT(child, next) == NULL); 8161 8162 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), 8163 child->bs->exact_filename); 8164 pstrcpy(bs->filename, sizeof(bs->filename), child->bs->filename); 8165 8166 qobject_unref(bs->full_open_options); 8167 bs->full_open_options = qobject_ref(child->bs->full_open_options); 8168 8169 return; 8170 } 8171 8172 backing_overridden = bdrv_backing_overridden(bs); 8173 8174 if (bs->open_flags & BDRV_O_NO_IO) { 8175 /* Without I/O, the backing file does not change anything. 8176 * Therefore, in such a case (primarily qemu-img), we can 8177 * pretend the backing file has not been overridden even if 8178 * it technically has been. */ 8179 backing_overridden = false; 8180 } 8181 8182 /* Gather the options QDict */ 8183 opts = qdict_new(); 8184 generate_json_filename = append_strong_runtime_options(opts, bs); 8185 generate_json_filename |= backing_overridden; 8186 8187 if (drv->bdrv_gather_child_options) { 8188 /* Some block drivers may not want to present all of their children's 8189 * options, or name them differently from BdrvChild.name */ 8190 drv->bdrv_gather_child_options(bs, opts, backing_overridden); 8191 } else { 8192 QLIST_FOREACH(child, &bs->children, next) { 8193 if (child == bs->backing && !backing_overridden) { 8194 /* We can skip the backing BDS if it has not been overridden */ 8195 continue; 8196 } 8197 8198 qdict_put(opts, child->name, 8199 qobject_ref(child->bs->full_open_options)); 8200 } 8201 8202 if (backing_overridden && !bs->backing) { 8203 /* Force no backing file */ 8204 qdict_put_null(opts, "backing"); 8205 } 8206 } 8207 8208 qobject_unref(bs->full_open_options); 8209 bs->full_open_options = opts; 8210 8211 primary_child_bs = bdrv_primary_bs(bs); 8212 8213 if (drv->bdrv_refresh_filename) { 8214 /* Obsolete information is of no use here, so drop the old file name 8215 * information before refreshing it */ 8216 bs->exact_filename[0] = '\0'; 8217 8218 drv->bdrv_refresh_filename(bs); 8219 } else if (primary_child_bs) { 8220 /* 8221 * Try to reconstruct valid information from the underlying 8222 * file -- this only works for format nodes (filter nodes 8223 * cannot be probed and as such must be selected by the user 8224 * either through an options dict, or through a special 8225 * filename which the filter driver must construct in its 8226 * .bdrv_refresh_filename() implementation). 8227 */ 8228 8229 bs->exact_filename[0] = '\0'; 8230 8231 /* 8232 * We can use the underlying file's filename if: 8233 * - it has a filename, 8234 * - the current BDS is not a filter, 8235 * - the file is a protocol BDS, and 8236 * - opening that file (as this BDS's format) will automatically create 8237 * the BDS tree we have right now, that is: 8238 * - the user did not significantly change this BDS's behavior with 8239 * some explicit (strong) options 8240 * - no non-file child of this BDS has been overridden by the user 8241 * Both of these conditions are represented by generate_json_filename. 8242 */ 8243 if (primary_child_bs->exact_filename[0] && 8244 primary_child_bs->drv->bdrv_file_open && 8245 !drv->is_filter && !generate_json_filename) 8246 { 8247 strcpy(bs->exact_filename, primary_child_bs->exact_filename); 8248 } 8249 } 8250 8251 if (bs->exact_filename[0]) { 8252 pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename); 8253 } else { 8254 GString *json = qobject_to_json(QOBJECT(bs->full_open_options)); 8255 if (snprintf(bs->filename, sizeof(bs->filename), "json:%s", 8256 json->str) >= sizeof(bs->filename)) { 8257 /* Give user a hint if we truncated things. */ 8258 strcpy(bs->filename + sizeof(bs->filename) - 4, "..."); 8259 } 8260 g_string_free(json, true); 8261 } 8262 } 8263 8264 char *bdrv_dirname(BlockDriverState *bs, Error **errp) 8265 { 8266 BlockDriver *drv = bs->drv; 8267 BlockDriverState *child_bs; 8268 8269 GLOBAL_STATE_CODE(); 8270 8271 if (!drv) { 8272 error_setg(errp, "Node '%s' is ejected", bs->node_name); 8273 return NULL; 8274 } 8275 8276 if (drv->bdrv_dirname) { 8277 return drv->bdrv_dirname(bs, errp); 8278 } 8279 8280 child_bs = bdrv_primary_bs(bs); 8281 if (child_bs) { 8282 return bdrv_dirname(child_bs, errp); 8283 } 8284 8285 bdrv_refresh_filename(bs); 8286 if (bs->exact_filename[0] != '\0') { 8287 return path_combine(bs->exact_filename, ""); 8288 } 8289 8290 error_setg(errp, "Cannot generate a base directory for %s nodes", 8291 drv->format_name); 8292 return NULL; 8293 } 8294 8295 /* 8296 * Hot add/remove a BDS's child. So the user can take a child offline when 8297 * it is broken and take a new child online 8298 */ 8299 void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs, 8300 Error **errp) 8301 { 8302 GLOBAL_STATE_CODE(); 8303 if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) { 8304 error_setg(errp, "The node %s does not support adding a child", 8305 bdrv_get_device_or_node_name(parent_bs)); 8306 return; 8307 } 8308 8309 /* 8310 * Non-zoned block drivers do not follow zoned storage constraints 8311 * (i.e. sequential writes to zones). Refuse mixing zoned and non-zoned 8312 * drivers in a graph. 8313 */ 8314 if (!parent_bs->drv->supports_zoned_children && 8315 child_bs->bl.zoned == BLK_Z_HM) { 8316 /* 8317 * The host-aware model allows zoned storage constraints and random 8318 * write. Allow mixing host-aware and non-zoned drivers. Using 8319 * host-aware device as a regular device. 8320 */ 8321 error_setg(errp, "Cannot add a %s child to a %s parent", 8322 child_bs->bl.zoned == BLK_Z_HM ? "zoned" : "non-zoned", 8323 parent_bs->drv->supports_zoned_children ? 8324 "support zoned children" : "not support zoned children"); 8325 return; 8326 } 8327 8328 if (!QLIST_EMPTY(&child_bs->parents)) { 8329 error_setg(errp, "The node %s already has a parent", 8330 child_bs->node_name); 8331 return; 8332 } 8333 8334 parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp); 8335 } 8336 8337 void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp) 8338 { 8339 BdrvChild *tmp; 8340 8341 GLOBAL_STATE_CODE(); 8342 if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) { 8343 error_setg(errp, "The node %s does not support removing a child", 8344 bdrv_get_device_or_node_name(parent_bs)); 8345 return; 8346 } 8347 8348 QLIST_FOREACH(tmp, &parent_bs->children, next) { 8349 if (tmp == child) { 8350 break; 8351 } 8352 } 8353 8354 if (!tmp) { 8355 error_setg(errp, "The node %s does not have a child named %s", 8356 bdrv_get_device_or_node_name(parent_bs), 8357 bdrv_get_device_or_node_name(child->bs)); 8358 return; 8359 } 8360 8361 parent_bs->drv->bdrv_del_child(parent_bs, child, errp); 8362 } 8363 8364 int bdrv_make_empty(BdrvChild *c, Error **errp) 8365 { 8366 BlockDriver *drv = c->bs->drv; 8367 int ret; 8368 8369 GLOBAL_STATE_CODE(); 8370 assert(c->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)); 8371 8372 if (!drv->bdrv_make_empty) { 8373 error_setg(errp, "%s does not support emptying nodes", 8374 drv->format_name); 8375 return -ENOTSUP; 8376 } 8377 8378 ret = drv->bdrv_make_empty(c->bs); 8379 if (ret < 0) { 8380 error_setg_errno(errp, -ret, "Failed to empty %s", 8381 c->bs->filename); 8382 return ret; 8383 } 8384 8385 return 0; 8386 } 8387 8388 /* 8389 * Return the child that @bs acts as an overlay for, and from which data may be 8390 * copied in COW or COR operations. Usually this is the backing file. 8391 */ 8392 BdrvChild *bdrv_cow_child(BlockDriverState *bs) 8393 { 8394 IO_CODE(); 8395 8396 if (!bs || !bs->drv) { 8397 return NULL; 8398 } 8399 8400 if (bs->drv->is_filter) { 8401 return NULL; 8402 } 8403 8404 if (!bs->backing) { 8405 return NULL; 8406 } 8407 8408 assert(bs->backing->role & BDRV_CHILD_COW); 8409 return bs->backing; 8410 } 8411 8412 /* 8413 * If @bs acts as a filter for exactly one of its children, return 8414 * that child. 8415 */ 8416 BdrvChild *bdrv_filter_child(BlockDriverState *bs) 8417 { 8418 BdrvChild *c; 8419 IO_CODE(); 8420 8421 if (!bs || !bs->drv) { 8422 return NULL; 8423 } 8424 8425 if (!bs->drv->is_filter) { 8426 return NULL; 8427 } 8428 8429 /* Only one of @backing or @file may be used */ 8430 assert(!(bs->backing && bs->file)); 8431 8432 c = bs->backing ?: bs->file; 8433 if (!c) { 8434 return NULL; 8435 } 8436 8437 assert(c->role & BDRV_CHILD_FILTERED); 8438 return c; 8439 } 8440 8441 /* 8442 * Return either the result of bdrv_cow_child() or bdrv_filter_child(), 8443 * whichever is non-NULL. 8444 * 8445 * Return NULL if both are NULL. 8446 */ 8447 BdrvChild *bdrv_filter_or_cow_child(BlockDriverState *bs) 8448 { 8449 BdrvChild *cow_child = bdrv_cow_child(bs); 8450 BdrvChild *filter_child = bdrv_filter_child(bs); 8451 IO_CODE(); 8452 8453 /* Filter nodes cannot have COW backing files */ 8454 assert(!(cow_child && filter_child)); 8455 8456 return cow_child ?: filter_child; 8457 } 8458 8459 /* 8460 * Return the primary child of this node: For filters, that is the 8461 * filtered child. For other nodes, that is usually the child storing 8462 * metadata. 8463 * (A generally more helpful description is that this is (usually) the 8464 * child that has the same filename as @bs.) 8465 * 8466 * Drivers do not necessarily have a primary child; for example quorum 8467 * does not. 8468 */ 8469 BdrvChild *bdrv_primary_child(BlockDriverState *bs) 8470 { 8471 BdrvChild *c, *found = NULL; 8472 IO_CODE(); 8473 8474 QLIST_FOREACH(c, &bs->children, next) { 8475 if (c->role & BDRV_CHILD_PRIMARY) { 8476 assert(!found); 8477 found = c; 8478 } 8479 } 8480 8481 return found; 8482 } 8483 8484 static BlockDriverState *bdrv_do_skip_filters(BlockDriverState *bs, 8485 bool stop_on_explicit_filter) 8486 { 8487 BdrvChild *c; 8488 8489 if (!bs) { 8490 return NULL; 8491 } 8492 8493 while (!(stop_on_explicit_filter && !bs->implicit)) { 8494 c = bdrv_filter_child(bs); 8495 if (!c) { 8496 /* 8497 * A filter that is embedded in a working block graph must 8498 * have a child. Assert this here so this function does 8499 * not return a filter node that is not expected by the 8500 * caller. 8501 */ 8502 assert(!bs->drv || !bs->drv->is_filter); 8503 break; 8504 } 8505 bs = c->bs; 8506 } 8507 /* 8508 * Note that this treats nodes with bs->drv == NULL as not being 8509 * filters (bs->drv == NULL should be replaced by something else 8510 * anyway). 8511 * The advantage of this behavior is that this function will thus 8512 * always return a non-NULL value (given a non-NULL @bs). 8513 */ 8514 8515 return bs; 8516 } 8517 8518 /* 8519 * Return the first BDS that has not been added implicitly or that 8520 * does not have a filtered child down the chain starting from @bs 8521 * (including @bs itself). 8522 */ 8523 BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs) 8524 { 8525 GLOBAL_STATE_CODE(); 8526 return bdrv_do_skip_filters(bs, true); 8527 } 8528 8529 /* 8530 * Return the first BDS that does not have a filtered child down the 8531 * chain starting from @bs (including @bs itself). 8532 */ 8533 BlockDriverState *bdrv_skip_filters(BlockDriverState *bs) 8534 { 8535 IO_CODE(); 8536 return bdrv_do_skip_filters(bs, false); 8537 } 8538 8539 /* 8540 * For a backing chain, return the first non-filter backing image of 8541 * the first non-filter image. 8542 */ 8543 BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs) 8544 { 8545 IO_CODE(); 8546 return bdrv_skip_filters(bdrv_cow_bs(bdrv_skip_filters(bs))); 8547 } 8548 8549 /** 8550 * Check whether [offset, offset + bytes) overlaps with the cached 8551 * block-status data region. 8552 * 8553 * If so, and @pnum is not NULL, set *pnum to `bsc.data_end - offset`, 8554 * which is what bdrv_bsc_is_data()'s interface needs. 8555 * Otherwise, *pnum is not touched. 8556 */ 8557 static bool bdrv_bsc_range_overlaps_locked(BlockDriverState *bs, 8558 int64_t offset, int64_t bytes, 8559 int64_t *pnum) 8560 { 8561 BdrvBlockStatusCache *bsc = qatomic_rcu_read(&bs->block_status_cache); 8562 bool overlaps; 8563 8564 overlaps = 8565 qatomic_read(&bsc->valid) && 8566 ranges_overlap(offset, bytes, bsc->data_start, 8567 bsc->data_end - bsc->data_start); 8568 8569 if (overlaps && pnum) { 8570 *pnum = bsc->data_end - offset; 8571 } 8572 8573 return overlaps; 8574 } 8575 8576 /** 8577 * See block_int.h for this function's documentation. 8578 */ 8579 bool bdrv_bsc_is_data(BlockDriverState *bs, int64_t offset, int64_t *pnum) 8580 { 8581 IO_CODE(); 8582 RCU_READ_LOCK_GUARD(); 8583 return bdrv_bsc_range_overlaps_locked(bs, offset, 1, pnum); 8584 } 8585 8586 /** 8587 * See block_int.h for this function's documentation. 8588 */ 8589 void bdrv_bsc_invalidate_range(BlockDriverState *bs, 8590 int64_t offset, int64_t bytes) 8591 { 8592 IO_CODE(); 8593 RCU_READ_LOCK_GUARD(); 8594 8595 if (bdrv_bsc_range_overlaps_locked(bs, offset, bytes, NULL)) { 8596 qatomic_set(&bs->block_status_cache->valid, false); 8597 } 8598 } 8599 8600 /** 8601 * See block_int.h for this function's documentation. 8602 */ 8603 void bdrv_bsc_fill(BlockDriverState *bs, int64_t offset, int64_t bytes) 8604 { 8605 BdrvBlockStatusCache *new_bsc = g_new(BdrvBlockStatusCache, 1); 8606 BdrvBlockStatusCache *old_bsc; 8607 IO_CODE(); 8608 8609 *new_bsc = (BdrvBlockStatusCache) { 8610 .valid = true, 8611 .data_start = offset, 8612 .data_end = offset + bytes, 8613 }; 8614 8615 QEMU_LOCK_GUARD(&bs->bsc_modify_lock); 8616 8617 old_bsc = qatomic_rcu_read(&bs->block_status_cache); 8618 qatomic_rcu_set(&bs->block_status_cache, new_bsc); 8619 if (old_bsc) { 8620 g_free_rcu(old_bsc, rcu); 8621 } 8622 } 8623