1 /* 2 * QEMU Enhanced Disk Format 3 * 4 * Copyright IBM, Corp. 2010 5 * 6 * Authors: 7 * Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> 8 * Anthony Liguori <aliguori@us.ibm.com> 9 * 10 * This work is licensed under the terms of the GNU LGPL, version 2 or later. 11 * See the COPYING.LIB file in the top-level directory. 12 * 13 */ 14 15 #include "qemu-timer.h" 16 #include "trace.h" 17 #include "qed.h" 18 #include "qerror.h" 19 20 static void qed_aio_cancel(BlockDriverAIOCB *blockacb) 21 { 22 QEDAIOCB *acb = (QEDAIOCB *)blockacb; 23 bool finished = false; 24 25 /* Wait for the request to finish */ 26 acb->finished = &finished; 27 while (!finished) { 28 qemu_aio_wait(); 29 } 30 } 31 32 static AIOPool qed_aio_pool = { 33 .aiocb_size = sizeof(QEDAIOCB), 34 .cancel = qed_aio_cancel, 35 }; 36 37 static int bdrv_qed_probe(const uint8_t *buf, int buf_size, 38 const char *filename) 39 { 40 const QEDHeader *header = (const QEDHeader *)buf; 41 42 if (buf_size < sizeof(*header)) { 43 return 0; 44 } 45 if (le32_to_cpu(header->magic) != QED_MAGIC) { 46 return 0; 47 } 48 return 100; 49 } 50 51 /** 52 * Check whether an image format is raw 53 * 54 * @fmt: Backing file format, may be NULL 55 */ 56 static bool qed_fmt_is_raw(const char *fmt) 57 { 58 return fmt && strcmp(fmt, "raw") == 0; 59 } 60 61 static void qed_header_le_to_cpu(const QEDHeader *le, QEDHeader *cpu) 62 { 63 cpu->magic = le32_to_cpu(le->magic); 64 cpu->cluster_size = le32_to_cpu(le->cluster_size); 65 cpu->table_size = le32_to_cpu(le->table_size); 66 cpu->header_size = le32_to_cpu(le->header_size); 67 cpu->features = le64_to_cpu(le->features); 68 cpu->compat_features = le64_to_cpu(le->compat_features); 69 cpu->autoclear_features = le64_to_cpu(le->autoclear_features); 70 cpu->l1_table_offset = le64_to_cpu(le->l1_table_offset); 71 cpu->image_size = le64_to_cpu(le->image_size); 72 cpu->backing_filename_offset = le32_to_cpu(le->backing_filename_offset); 73 cpu->backing_filename_size = le32_to_cpu(le->backing_filename_size); 74 } 75 76 static void qed_header_cpu_to_le(const QEDHeader *cpu, QEDHeader *le) 77 { 78 le->magic = cpu_to_le32(cpu->magic); 79 le->cluster_size = cpu_to_le32(cpu->cluster_size); 80 le->table_size = cpu_to_le32(cpu->table_size); 81 le->header_size = cpu_to_le32(cpu->header_size); 82 le->features = cpu_to_le64(cpu->features); 83 le->compat_features = cpu_to_le64(cpu->compat_features); 84 le->autoclear_features = cpu_to_le64(cpu->autoclear_features); 85 le->l1_table_offset = cpu_to_le64(cpu->l1_table_offset); 86 le->image_size = cpu_to_le64(cpu->image_size); 87 le->backing_filename_offset = cpu_to_le32(cpu->backing_filename_offset); 88 le->backing_filename_size = cpu_to_le32(cpu->backing_filename_size); 89 } 90 91 static int qed_write_header_sync(BDRVQEDState *s) 92 { 93 QEDHeader le; 94 int ret; 95 96 qed_header_cpu_to_le(&s->header, &le); 97 ret = bdrv_pwrite(s->bs->file, 0, &le, sizeof(le)); 98 if (ret != sizeof(le)) { 99 return ret; 100 } 101 return 0; 102 } 103 104 typedef struct { 105 GenericCB gencb; 106 BDRVQEDState *s; 107 struct iovec iov; 108 QEMUIOVector qiov; 109 int nsectors; 110 uint8_t *buf; 111 } QEDWriteHeaderCB; 112 113 static void qed_write_header_cb(void *opaque, int ret) 114 { 115 QEDWriteHeaderCB *write_header_cb = opaque; 116 117 qemu_vfree(write_header_cb->buf); 118 gencb_complete(write_header_cb, ret); 119 } 120 121 static void qed_write_header_read_cb(void *opaque, int ret) 122 { 123 QEDWriteHeaderCB *write_header_cb = opaque; 124 BDRVQEDState *s = write_header_cb->s; 125 BlockDriverAIOCB *acb; 126 127 if (ret) { 128 qed_write_header_cb(write_header_cb, ret); 129 return; 130 } 131 132 /* Update header */ 133 qed_header_cpu_to_le(&s->header, (QEDHeader *)write_header_cb->buf); 134 135 acb = bdrv_aio_writev(s->bs->file, 0, &write_header_cb->qiov, 136 write_header_cb->nsectors, qed_write_header_cb, 137 write_header_cb); 138 if (!acb) { 139 qed_write_header_cb(write_header_cb, -EIO); 140 } 141 } 142 143 /** 144 * Update header in-place (does not rewrite backing filename or other strings) 145 * 146 * This function only updates known header fields in-place and does not affect 147 * extra data after the QED header. 148 */ 149 static void qed_write_header(BDRVQEDState *s, BlockDriverCompletionFunc cb, 150 void *opaque) 151 { 152 /* We must write full sectors for O_DIRECT but cannot necessarily generate 153 * the data following the header if an unrecognized compat feature is 154 * active. Therefore, first read the sectors containing the header, update 155 * them, and write back. 156 */ 157 158 BlockDriverAIOCB *acb; 159 int nsectors = (sizeof(QEDHeader) + BDRV_SECTOR_SIZE - 1) / 160 BDRV_SECTOR_SIZE; 161 size_t len = nsectors * BDRV_SECTOR_SIZE; 162 QEDWriteHeaderCB *write_header_cb = gencb_alloc(sizeof(*write_header_cb), 163 cb, opaque); 164 165 write_header_cb->s = s; 166 write_header_cb->nsectors = nsectors; 167 write_header_cb->buf = qemu_blockalign(s->bs, len); 168 write_header_cb->iov.iov_base = write_header_cb->buf; 169 write_header_cb->iov.iov_len = len; 170 qemu_iovec_init_external(&write_header_cb->qiov, &write_header_cb->iov, 1); 171 172 acb = bdrv_aio_readv(s->bs->file, 0, &write_header_cb->qiov, nsectors, 173 qed_write_header_read_cb, write_header_cb); 174 if (!acb) { 175 qed_write_header_cb(write_header_cb, -EIO); 176 } 177 } 178 179 static uint64_t qed_max_image_size(uint32_t cluster_size, uint32_t table_size) 180 { 181 uint64_t table_entries; 182 uint64_t l2_size; 183 184 table_entries = (table_size * cluster_size) / sizeof(uint64_t); 185 l2_size = table_entries * cluster_size; 186 187 return l2_size * table_entries; 188 } 189 190 static bool qed_is_cluster_size_valid(uint32_t cluster_size) 191 { 192 if (cluster_size < QED_MIN_CLUSTER_SIZE || 193 cluster_size > QED_MAX_CLUSTER_SIZE) { 194 return false; 195 } 196 if (cluster_size & (cluster_size - 1)) { 197 return false; /* not power of 2 */ 198 } 199 return true; 200 } 201 202 static bool qed_is_table_size_valid(uint32_t table_size) 203 { 204 if (table_size < QED_MIN_TABLE_SIZE || 205 table_size > QED_MAX_TABLE_SIZE) { 206 return false; 207 } 208 if (table_size & (table_size - 1)) { 209 return false; /* not power of 2 */ 210 } 211 return true; 212 } 213 214 static bool qed_is_image_size_valid(uint64_t image_size, uint32_t cluster_size, 215 uint32_t table_size) 216 { 217 if (image_size % BDRV_SECTOR_SIZE != 0) { 218 return false; /* not multiple of sector size */ 219 } 220 if (image_size > qed_max_image_size(cluster_size, table_size)) { 221 return false; /* image is too large */ 222 } 223 return true; 224 } 225 226 /** 227 * Read a string of known length from the image file 228 * 229 * @file: Image file 230 * @offset: File offset to start of string, in bytes 231 * @n: String length in bytes 232 * @buf: Destination buffer 233 * @buflen: Destination buffer length in bytes 234 * @ret: 0 on success, -errno on failure 235 * 236 * The string is NUL-terminated. 237 */ 238 static int qed_read_string(BlockDriverState *file, uint64_t offset, size_t n, 239 char *buf, size_t buflen) 240 { 241 int ret; 242 if (n >= buflen) { 243 return -EINVAL; 244 } 245 ret = bdrv_pread(file, offset, buf, n); 246 if (ret < 0) { 247 return ret; 248 } 249 buf[n] = '\0'; 250 return 0; 251 } 252 253 /** 254 * Allocate new clusters 255 * 256 * @s: QED state 257 * @n: Number of contiguous clusters to allocate 258 * @ret: Offset of first allocated cluster 259 * 260 * This function only produces the offset where the new clusters should be 261 * written. It updates BDRVQEDState but does not make any changes to the image 262 * file. 263 */ 264 static uint64_t qed_alloc_clusters(BDRVQEDState *s, unsigned int n) 265 { 266 uint64_t offset = s->file_size; 267 s->file_size += n * s->header.cluster_size; 268 return offset; 269 } 270 271 QEDTable *qed_alloc_table(BDRVQEDState *s) 272 { 273 /* Honor O_DIRECT memory alignment requirements */ 274 return qemu_blockalign(s->bs, 275 s->header.cluster_size * s->header.table_size); 276 } 277 278 /** 279 * Allocate a new zeroed L2 table 280 */ 281 static CachedL2Table *qed_new_l2_table(BDRVQEDState *s) 282 { 283 CachedL2Table *l2_table = qed_alloc_l2_cache_entry(&s->l2_cache); 284 285 l2_table->table = qed_alloc_table(s); 286 l2_table->offset = qed_alloc_clusters(s, s->header.table_size); 287 288 memset(l2_table->table->offsets, 0, 289 s->header.cluster_size * s->header.table_size); 290 return l2_table; 291 } 292 293 static void qed_aio_next_io(void *opaque, int ret); 294 295 static void qed_plug_allocating_write_reqs(BDRVQEDState *s) 296 { 297 assert(!s->allocating_write_reqs_plugged); 298 299 s->allocating_write_reqs_plugged = true; 300 } 301 302 static void qed_unplug_allocating_write_reqs(BDRVQEDState *s) 303 { 304 QEDAIOCB *acb; 305 306 assert(s->allocating_write_reqs_plugged); 307 308 s->allocating_write_reqs_plugged = false; 309 310 acb = QSIMPLEQ_FIRST(&s->allocating_write_reqs); 311 if (acb) { 312 qed_aio_next_io(acb, 0); 313 } 314 } 315 316 static void qed_finish_clear_need_check(void *opaque, int ret) 317 { 318 /* Do nothing */ 319 } 320 321 static void qed_flush_after_clear_need_check(void *opaque, int ret) 322 { 323 BDRVQEDState *s = opaque; 324 325 bdrv_aio_flush(s->bs, qed_finish_clear_need_check, s); 326 327 /* No need to wait until flush completes */ 328 qed_unplug_allocating_write_reqs(s); 329 } 330 331 static void qed_clear_need_check(void *opaque, int ret) 332 { 333 BDRVQEDState *s = opaque; 334 335 if (ret) { 336 qed_unplug_allocating_write_reqs(s); 337 return; 338 } 339 340 s->header.features &= ~QED_F_NEED_CHECK; 341 qed_write_header(s, qed_flush_after_clear_need_check, s); 342 } 343 344 static void qed_need_check_timer_cb(void *opaque) 345 { 346 BDRVQEDState *s = opaque; 347 348 /* The timer should only fire when allocating writes have drained */ 349 assert(!QSIMPLEQ_FIRST(&s->allocating_write_reqs)); 350 351 trace_qed_need_check_timer_cb(s); 352 353 qed_plug_allocating_write_reqs(s); 354 355 /* Ensure writes are on disk before clearing flag */ 356 bdrv_aio_flush(s->bs, qed_clear_need_check, s); 357 } 358 359 static void qed_start_need_check_timer(BDRVQEDState *s) 360 { 361 trace_qed_start_need_check_timer(s); 362 363 /* Use vm_clock so we don't alter the image file while suspended for 364 * migration. 365 */ 366 qemu_mod_timer(s->need_check_timer, qemu_get_clock_ns(vm_clock) + 367 get_ticks_per_sec() * QED_NEED_CHECK_TIMEOUT); 368 } 369 370 /* It's okay to call this multiple times or when no timer is started */ 371 static void qed_cancel_need_check_timer(BDRVQEDState *s) 372 { 373 trace_qed_cancel_need_check_timer(s); 374 qemu_del_timer(s->need_check_timer); 375 } 376 377 static int bdrv_qed_open(BlockDriverState *bs, int flags) 378 { 379 BDRVQEDState *s = bs->opaque; 380 QEDHeader le_header; 381 int64_t file_size; 382 int ret; 383 384 s->bs = bs; 385 QSIMPLEQ_INIT(&s->allocating_write_reqs); 386 387 ret = bdrv_pread(bs->file, 0, &le_header, sizeof(le_header)); 388 if (ret < 0) { 389 return ret; 390 } 391 ret = 0; /* ret should always be 0 or -errno */ 392 qed_header_le_to_cpu(&le_header, &s->header); 393 394 if (s->header.magic != QED_MAGIC) { 395 return -EINVAL; 396 } 397 if (s->header.features & ~QED_FEATURE_MASK) { 398 /* image uses unsupported feature bits */ 399 char buf[64]; 400 snprintf(buf, sizeof(buf), "%" PRIx64, 401 s->header.features & ~QED_FEATURE_MASK); 402 qerror_report(QERR_UNKNOWN_BLOCK_FORMAT_FEATURE, 403 bs->device_name, "QED", buf); 404 return -ENOTSUP; 405 } 406 if (!qed_is_cluster_size_valid(s->header.cluster_size)) { 407 return -EINVAL; 408 } 409 410 /* Round down file size to the last cluster */ 411 file_size = bdrv_getlength(bs->file); 412 if (file_size < 0) { 413 return file_size; 414 } 415 s->file_size = qed_start_of_cluster(s, file_size); 416 417 if (!qed_is_table_size_valid(s->header.table_size)) { 418 return -EINVAL; 419 } 420 if (!qed_is_image_size_valid(s->header.image_size, 421 s->header.cluster_size, 422 s->header.table_size)) { 423 return -EINVAL; 424 } 425 if (!qed_check_table_offset(s, s->header.l1_table_offset)) { 426 return -EINVAL; 427 } 428 429 s->table_nelems = (s->header.cluster_size * s->header.table_size) / 430 sizeof(uint64_t); 431 s->l2_shift = ffs(s->header.cluster_size) - 1; 432 s->l2_mask = s->table_nelems - 1; 433 s->l1_shift = s->l2_shift + ffs(s->table_nelems) - 1; 434 435 if ((s->header.features & QED_F_BACKING_FILE)) { 436 if ((uint64_t)s->header.backing_filename_offset + 437 s->header.backing_filename_size > 438 s->header.cluster_size * s->header.header_size) { 439 return -EINVAL; 440 } 441 442 ret = qed_read_string(bs->file, s->header.backing_filename_offset, 443 s->header.backing_filename_size, bs->backing_file, 444 sizeof(bs->backing_file)); 445 if (ret < 0) { 446 return ret; 447 } 448 449 if (s->header.features & QED_F_BACKING_FORMAT_NO_PROBE) { 450 pstrcpy(bs->backing_format, sizeof(bs->backing_format), "raw"); 451 } 452 } 453 454 /* Reset unknown autoclear feature bits. This is a backwards 455 * compatibility mechanism that allows images to be opened by older 456 * programs, which "knock out" unknown feature bits. When an image is 457 * opened by a newer program again it can detect that the autoclear 458 * feature is no longer valid. 459 */ 460 if ((s->header.autoclear_features & ~QED_AUTOCLEAR_FEATURE_MASK) != 0 && 461 !bdrv_is_read_only(bs->file)) { 462 s->header.autoclear_features &= QED_AUTOCLEAR_FEATURE_MASK; 463 464 ret = qed_write_header_sync(s); 465 if (ret) { 466 return ret; 467 } 468 469 /* From here on only known autoclear feature bits are valid */ 470 bdrv_flush(bs->file); 471 } 472 473 s->l1_table = qed_alloc_table(s); 474 qed_init_l2_cache(&s->l2_cache); 475 476 ret = qed_read_l1_table_sync(s); 477 if (ret) { 478 goto out; 479 } 480 481 /* If image was not closed cleanly, check consistency */ 482 if (s->header.features & QED_F_NEED_CHECK) { 483 /* Read-only images cannot be fixed. There is no risk of corruption 484 * since write operations are not possible. Therefore, allow 485 * potentially inconsistent images to be opened read-only. This can 486 * aid data recovery from an otherwise inconsistent image. 487 */ 488 if (!bdrv_is_read_only(bs->file)) { 489 BdrvCheckResult result = {0}; 490 491 ret = qed_check(s, &result, true); 492 if (ret) { 493 goto out; 494 } 495 if (!result.corruptions && !result.check_errors) { 496 /* Ensure fixes reach storage before clearing check bit */ 497 bdrv_flush(s->bs); 498 499 s->header.features &= ~QED_F_NEED_CHECK; 500 qed_write_header_sync(s); 501 } 502 } 503 } 504 505 s->need_check_timer = qemu_new_timer_ns(vm_clock, 506 qed_need_check_timer_cb, s); 507 508 out: 509 if (ret) { 510 qed_free_l2_cache(&s->l2_cache); 511 qemu_vfree(s->l1_table); 512 } 513 return ret; 514 } 515 516 static void bdrv_qed_close(BlockDriverState *bs) 517 { 518 BDRVQEDState *s = bs->opaque; 519 520 qed_cancel_need_check_timer(s); 521 qemu_free_timer(s->need_check_timer); 522 523 /* Ensure writes reach stable storage */ 524 bdrv_flush(bs->file); 525 526 /* Clean shutdown, no check required on next open */ 527 if (s->header.features & QED_F_NEED_CHECK) { 528 s->header.features &= ~QED_F_NEED_CHECK; 529 qed_write_header_sync(s); 530 } 531 532 qed_free_l2_cache(&s->l2_cache); 533 qemu_vfree(s->l1_table); 534 } 535 536 static int bdrv_qed_flush(BlockDriverState *bs) 537 { 538 return bdrv_flush(bs->file); 539 } 540 541 static int qed_create(const char *filename, uint32_t cluster_size, 542 uint64_t image_size, uint32_t table_size, 543 const char *backing_file, const char *backing_fmt) 544 { 545 QEDHeader header = { 546 .magic = QED_MAGIC, 547 .cluster_size = cluster_size, 548 .table_size = table_size, 549 .header_size = 1, 550 .features = 0, 551 .compat_features = 0, 552 .l1_table_offset = cluster_size, 553 .image_size = image_size, 554 }; 555 QEDHeader le_header; 556 uint8_t *l1_table = NULL; 557 size_t l1_size = header.cluster_size * header.table_size; 558 int ret = 0; 559 BlockDriverState *bs = NULL; 560 561 ret = bdrv_create_file(filename, NULL); 562 if (ret < 0) { 563 return ret; 564 } 565 566 ret = bdrv_file_open(&bs, filename, BDRV_O_RDWR | BDRV_O_CACHE_WB); 567 if (ret < 0) { 568 return ret; 569 } 570 571 /* File must start empty and grow, check truncate is supported */ 572 ret = bdrv_truncate(bs, 0); 573 if (ret < 0) { 574 goto out; 575 } 576 577 if (backing_file) { 578 header.features |= QED_F_BACKING_FILE; 579 header.backing_filename_offset = sizeof(le_header); 580 header.backing_filename_size = strlen(backing_file); 581 582 if (qed_fmt_is_raw(backing_fmt)) { 583 header.features |= QED_F_BACKING_FORMAT_NO_PROBE; 584 } 585 } 586 587 qed_header_cpu_to_le(&header, &le_header); 588 ret = bdrv_pwrite(bs, 0, &le_header, sizeof(le_header)); 589 if (ret < 0) { 590 goto out; 591 } 592 ret = bdrv_pwrite(bs, sizeof(le_header), backing_file, 593 header.backing_filename_size); 594 if (ret < 0) { 595 goto out; 596 } 597 598 l1_table = g_malloc0(l1_size); 599 ret = bdrv_pwrite(bs, header.l1_table_offset, l1_table, l1_size); 600 if (ret < 0) { 601 goto out; 602 } 603 604 ret = 0; /* success */ 605 out: 606 g_free(l1_table); 607 bdrv_delete(bs); 608 return ret; 609 } 610 611 static int bdrv_qed_create(const char *filename, QEMUOptionParameter *options) 612 { 613 uint64_t image_size = 0; 614 uint32_t cluster_size = QED_DEFAULT_CLUSTER_SIZE; 615 uint32_t table_size = QED_DEFAULT_TABLE_SIZE; 616 const char *backing_file = NULL; 617 const char *backing_fmt = NULL; 618 619 while (options && options->name) { 620 if (!strcmp(options->name, BLOCK_OPT_SIZE)) { 621 image_size = options->value.n; 622 } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) { 623 backing_file = options->value.s; 624 } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FMT)) { 625 backing_fmt = options->value.s; 626 } else if (!strcmp(options->name, BLOCK_OPT_CLUSTER_SIZE)) { 627 if (options->value.n) { 628 cluster_size = options->value.n; 629 } 630 } else if (!strcmp(options->name, BLOCK_OPT_TABLE_SIZE)) { 631 if (options->value.n) { 632 table_size = options->value.n; 633 } 634 } 635 options++; 636 } 637 638 if (!qed_is_cluster_size_valid(cluster_size)) { 639 fprintf(stderr, "QED cluster size must be within range [%u, %u] and power of 2\n", 640 QED_MIN_CLUSTER_SIZE, QED_MAX_CLUSTER_SIZE); 641 return -EINVAL; 642 } 643 if (!qed_is_table_size_valid(table_size)) { 644 fprintf(stderr, "QED table size must be within range [%u, %u] and power of 2\n", 645 QED_MIN_TABLE_SIZE, QED_MAX_TABLE_SIZE); 646 return -EINVAL; 647 } 648 if (!qed_is_image_size_valid(image_size, cluster_size, table_size)) { 649 fprintf(stderr, "QED image size must be a non-zero multiple of " 650 "cluster size and less than %" PRIu64 " bytes\n", 651 qed_max_image_size(cluster_size, table_size)); 652 return -EINVAL; 653 } 654 655 return qed_create(filename, cluster_size, image_size, table_size, 656 backing_file, backing_fmt); 657 } 658 659 typedef struct { 660 int is_allocated; 661 int *pnum; 662 } QEDIsAllocatedCB; 663 664 static void qed_is_allocated_cb(void *opaque, int ret, uint64_t offset, size_t len) 665 { 666 QEDIsAllocatedCB *cb = opaque; 667 *cb->pnum = len / BDRV_SECTOR_SIZE; 668 cb->is_allocated = (ret == QED_CLUSTER_FOUND || ret == QED_CLUSTER_ZERO); 669 } 670 671 static int bdrv_qed_is_allocated(BlockDriverState *bs, int64_t sector_num, 672 int nb_sectors, int *pnum) 673 { 674 BDRVQEDState *s = bs->opaque; 675 uint64_t pos = (uint64_t)sector_num * BDRV_SECTOR_SIZE; 676 size_t len = (size_t)nb_sectors * BDRV_SECTOR_SIZE; 677 QEDIsAllocatedCB cb = { 678 .is_allocated = -1, 679 .pnum = pnum, 680 }; 681 QEDRequest request = { .l2_table = NULL }; 682 683 qed_find_cluster(s, &request, pos, len, qed_is_allocated_cb, &cb); 684 685 while (cb.is_allocated == -1) { 686 qemu_aio_wait(); 687 } 688 689 qed_unref_l2_cache_entry(request.l2_table); 690 691 return cb.is_allocated; 692 } 693 694 static int bdrv_qed_make_empty(BlockDriverState *bs) 695 { 696 return -ENOTSUP; 697 } 698 699 static BDRVQEDState *acb_to_s(QEDAIOCB *acb) 700 { 701 return acb->common.bs->opaque; 702 } 703 704 /** 705 * Read from the backing file or zero-fill if no backing file 706 * 707 * @s: QED state 708 * @pos: Byte position in device 709 * @qiov: Destination I/O vector 710 * @cb: Completion function 711 * @opaque: User data for completion function 712 * 713 * This function reads qiov->size bytes starting at pos from the backing file. 714 * If there is no backing file then zeroes are read. 715 */ 716 static void qed_read_backing_file(BDRVQEDState *s, uint64_t pos, 717 QEMUIOVector *qiov, 718 BlockDriverCompletionFunc *cb, void *opaque) 719 { 720 BlockDriverAIOCB *aiocb; 721 uint64_t backing_length = 0; 722 size_t size; 723 724 /* If there is a backing file, get its length. Treat the absence of a 725 * backing file like a zero length backing file. 726 */ 727 if (s->bs->backing_hd) { 728 int64_t l = bdrv_getlength(s->bs->backing_hd); 729 if (l < 0) { 730 cb(opaque, l); 731 return; 732 } 733 backing_length = l; 734 } 735 736 /* Zero all sectors if reading beyond the end of the backing file */ 737 if (pos >= backing_length || 738 pos + qiov->size > backing_length) { 739 qemu_iovec_memset(qiov, 0, qiov->size); 740 } 741 742 /* Complete now if there are no backing file sectors to read */ 743 if (pos >= backing_length) { 744 cb(opaque, 0); 745 return; 746 } 747 748 /* If the read straddles the end of the backing file, shorten it */ 749 size = MIN((uint64_t)backing_length - pos, qiov->size); 750 751 BLKDBG_EVENT(s->bs->file, BLKDBG_READ_BACKING); 752 aiocb = bdrv_aio_readv(s->bs->backing_hd, pos / BDRV_SECTOR_SIZE, 753 qiov, size / BDRV_SECTOR_SIZE, cb, opaque); 754 if (!aiocb) { 755 cb(opaque, -EIO); 756 } 757 } 758 759 typedef struct { 760 GenericCB gencb; 761 BDRVQEDState *s; 762 QEMUIOVector qiov; 763 struct iovec iov; 764 uint64_t offset; 765 } CopyFromBackingFileCB; 766 767 static void qed_copy_from_backing_file_cb(void *opaque, int ret) 768 { 769 CopyFromBackingFileCB *copy_cb = opaque; 770 qemu_vfree(copy_cb->iov.iov_base); 771 gencb_complete(©_cb->gencb, ret); 772 } 773 774 static void qed_copy_from_backing_file_write(void *opaque, int ret) 775 { 776 CopyFromBackingFileCB *copy_cb = opaque; 777 BDRVQEDState *s = copy_cb->s; 778 BlockDriverAIOCB *aiocb; 779 780 if (ret) { 781 qed_copy_from_backing_file_cb(copy_cb, ret); 782 return; 783 } 784 785 BLKDBG_EVENT(s->bs->file, BLKDBG_COW_WRITE); 786 aiocb = bdrv_aio_writev(s->bs->file, copy_cb->offset / BDRV_SECTOR_SIZE, 787 ©_cb->qiov, 788 copy_cb->qiov.size / BDRV_SECTOR_SIZE, 789 qed_copy_from_backing_file_cb, copy_cb); 790 if (!aiocb) { 791 qed_copy_from_backing_file_cb(copy_cb, -EIO); 792 } 793 } 794 795 /** 796 * Copy data from backing file into the image 797 * 798 * @s: QED state 799 * @pos: Byte position in device 800 * @len: Number of bytes 801 * @offset: Byte offset in image file 802 * @cb: Completion function 803 * @opaque: User data for completion function 804 */ 805 static void qed_copy_from_backing_file(BDRVQEDState *s, uint64_t pos, 806 uint64_t len, uint64_t offset, 807 BlockDriverCompletionFunc *cb, 808 void *opaque) 809 { 810 CopyFromBackingFileCB *copy_cb; 811 812 /* Skip copy entirely if there is no work to do */ 813 if (len == 0) { 814 cb(opaque, 0); 815 return; 816 } 817 818 copy_cb = gencb_alloc(sizeof(*copy_cb), cb, opaque); 819 copy_cb->s = s; 820 copy_cb->offset = offset; 821 copy_cb->iov.iov_base = qemu_blockalign(s->bs, len); 822 copy_cb->iov.iov_len = len; 823 qemu_iovec_init_external(©_cb->qiov, ©_cb->iov, 1); 824 825 qed_read_backing_file(s, pos, ©_cb->qiov, 826 qed_copy_from_backing_file_write, copy_cb); 827 } 828 829 /** 830 * Link one or more contiguous clusters into a table 831 * 832 * @s: QED state 833 * @table: L2 table 834 * @index: First cluster index 835 * @n: Number of contiguous clusters 836 * @cluster: First cluster offset 837 * 838 * The cluster offset may be an allocated byte offset in the image file, the 839 * zero cluster marker, or the unallocated cluster marker. 840 */ 841 static void qed_update_l2_table(BDRVQEDState *s, QEDTable *table, int index, 842 unsigned int n, uint64_t cluster) 843 { 844 int i; 845 for (i = index; i < index + n; i++) { 846 table->offsets[i] = cluster; 847 if (!qed_offset_is_unalloc_cluster(cluster) && 848 !qed_offset_is_zero_cluster(cluster)) { 849 cluster += s->header.cluster_size; 850 } 851 } 852 } 853 854 static void qed_aio_complete_bh(void *opaque) 855 { 856 QEDAIOCB *acb = opaque; 857 BlockDriverCompletionFunc *cb = acb->common.cb; 858 void *user_opaque = acb->common.opaque; 859 int ret = acb->bh_ret; 860 bool *finished = acb->finished; 861 862 qemu_bh_delete(acb->bh); 863 qemu_aio_release(acb); 864 865 /* Invoke callback */ 866 cb(user_opaque, ret); 867 868 /* Signal cancel completion */ 869 if (finished) { 870 *finished = true; 871 } 872 } 873 874 static void qed_aio_complete(QEDAIOCB *acb, int ret) 875 { 876 BDRVQEDState *s = acb_to_s(acb); 877 878 trace_qed_aio_complete(s, acb, ret); 879 880 /* Free resources */ 881 qemu_iovec_destroy(&acb->cur_qiov); 882 qed_unref_l2_cache_entry(acb->request.l2_table); 883 884 /* Arrange for a bh to invoke the completion function */ 885 acb->bh_ret = ret; 886 acb->bh = qemu_bh_new(qed_aio_complete_bh, acb); 887 qemu_bh_schedule(acb->bh); 888 889 /* Start next allocating write request waiting behind this one. Note that 890 * requests enqueue themselves when they first hit an unallocated cluster 891 * but they wait until the entire request is finished before waking up the 892 * next request in the queue. This ensures that we don't cycle through 893 * requests multiple times but rather finish one at a time completely. 894 */ 895 if (acb == QSIMPLEQ_FIRST(&s->allocating_write_reqs)) { 896 QSIMPLEQ_REMOVE_HEAD(&s->allocating_write_reqs, next); 897 acb = QSIMPLEQ_FIRST(&s->allocating_write_reqs); 898 if (acb) { 899 qed_aio_next_io(acb, 0); 900 } else if (s->header.features & QED_F_NEED_CHECK) { 901 qed_start_need_check_timer(s); 902 } 903 } 904 } 905 906 /** 907 * Commit the current L2 table to the cache 908 */ 909 static void qed_commit_l2_update(void *opaque, int ret) 910 { 911 QEDAIOCB *acb = opaque; 912 BDRVQEDState *s = acb_to_s(acb); 913 CachedL2Table *l2_table = acb->request.l2_table; 914 915 qed_commit_l2_cache_entry(&s->l2_cache, l2_table); 916 917 /* This is guaranteed to succeed because we just committed the entry to the 918 * cache. 919 */ 920 acb->request.l2_table = qed_find_l2_cache_entry(&s->l2_cache, 921 l2_table->offset); 922 assert(acb->request.l2_table != NULL); 923 924 qed_aio_next_io(opaque, ret); 925 } 926 927 /** 928 * Update L1 table with new L2 table offset and write it out 929 */ 930 static void qed_aio_write_l1_update(void *opaque, int ret) 931 { 932 QEDAIOCB *acb = opaque; 933 BDRVQEDState *s = acb_to_s(acb); 934 int index; 935 936 if (ret) { 937 qed_aio_complete(acb, ret); 938 return; 939 } 940 941 index = qed_l1_index(s, acb->cur_pos); 942 s->l1_table->offsets[index] = acb->request.l2_table->offset; 943 944 qed_write_l1_table(s, index, 1, qed_commit_l2_update, acb); 945 } 946 947 /** 948 * Update L2 table with new cluster offsets and write them out 949 */ 950 static void qed_aio_write_l2_update(void *opaque, int ret) 951 { 952 QEDAIOCB *acb = opaque; 953 BDRVQEDState *s = acb_to_s(acb); 954 bool need_alloc = acb->find_cluster_ret == QED_CLUSTER_L1; 955 int index; 956 957 if (ret) { 958 goto err; 959 } 960 961 if (need_alloc) { 962 qed_unref_l2_cache_entry(acb->request.l2_table); 963 acb->request.l2_table = qed_new_l2_table(s); 964 } 965 966 index = qed_l2_index(s, acb->cur_pos); 967 qed_update_l2_table(s, acb->request.l2_table->table, index, acb->cur_nclusters, 968 acb->cur_cluster); 969 970 if (need_alloc) { 971 /* Write out the whole new L2 table */ 972 qed_write_l2_table(s, &acb->request, 0, s->table_nelems, true, 973 qed_aio_write_l1_update, acb); 974 } else { 975 /* Write out only the updated part of the L2 table */ 976 qed_write_l2_table(s, &acb->request, index, acb->cur_nclusters, false, 977 qed_aio_next_io, acb); 978 } 979 return; 980 981 err: 982 qed_aio_complete(acb, ret); 983 } 984 985 /** 986 * Flush new data clusters before updating the L2 table 987 * 988 * This flush is necessary when a backing file is in use. A crash during an 989 * allocating write could result in empty clusters in the image. If the write 990 * only touched a subregion of the cluster, then backing image sectors have 991 * been lost in the untouched region. The solution is to flush after writing a 992 * new data cluster and before updating the L2 table. 993 */ 994 static void qed_aio_write_flush_before_l2_update(void *opaque, int ret) 995 { 996 QEDAIOCB *acb = opaque; 997 BDRVQEDState *s = acb_to_s(acb); 998 999 if (!bdrv_aio_flush(s->bs->file, qed_aio_write_l2_update, opaque)) { 1000 qed_aio_complete(acb, -EIO); 1001 } 1002 } 1003 1004 /** 1005 * Write data to the image file 1006 */ 1007 static void qed_aio_write_main(void *opaque, int ret) 1008 { 1009 QEDAIOCB *acb = opaque; 1010 BDRVQEDState *s = acb_to_s(acb); 1011 uint64_t offset = acb->cur_cluster + 1012 qed_offset_into_cluster(s, acb->cur_pos); 1013 BlockDriverCompletionFunc *next_fn; 1014 BlockDriverAIOCB *file_acb; 1015 1016 trace_qed_aio_write_main(s, acb, ret, offset, acb->cur_qiov.size); 1017 1018 if (ret) { 1019 qed_aio_complete(acb, ret); 1020 return; 1021 } 1022 1023 if (acb->find_cluster_ret == QED_CLUSTER_FOUND) { 1024 next_fn = qed_aio_next_io; 1025 } else { 1026 if (s->bs->backing_hd) { 1027 next_fn = qed_aio_write_flush_before_l2_update; 1028 } else { 1029 next_fn = qed_aio_write_l2_update; 1030 } 1031 } 1032 1033 BLKDBG_EVENT(s->bs->file, BLKDBG_WRITE_AIO); 1034 file_acb = bdrv_aio_writev(s->bs->file, offset / BDRV_SECTOR_SIZE, 1035 &acb->cur_qiov, 1036 acb->cur_qiov.size / BDRV_SECTOR_SIZE, 1037 next_fn, acb); 1038 if (!file_acb) { 1039 qed_aio_complete(acb, -EIO); 1040 } 1041 } 1042 1043 /** 1044 * Populate back untouched region of new data cluster 1045 */ 1046 static void qed_aio_write_postfill(void *opaque, int ret) 1047 { 1048 QEDAIOCB *acb = opaque; 1049 BDRVQEDState *s = acb_to_s(acb); 1050 uint64_t start = acb->cur_pos + acb->cur_qiov.size; 1051 uint64_t len = 1052 qed_start_of_cluster(s, start + s->header.cluster_size - 1) - start; 1053 uint64_t offset = acb->cur_cluster + 1054 qed_offset_into_cluster(s, acb->cur_pos) + 1055 acb->cur_qiov.size; 1056 1057 if (ret) { 1058 qed_aio_complete(acb, ret); 1059 return; 1060 } 1061 1062 trace_qed_aio_write_postfill(s, acb, start, len, offset); 1063 qed_copy_from_backing_file(s, start, len, offset, 1064 qed_aio_write_main, acb); 1065 } 1066 1067 /** 1068 * Populate front untouched region of new data cluster 1069 */ 1070 static void qed_aio_write_prefill(void *opaque, int ret) 1071 { 1072 QEDAIOCB *acb = opaque; 1073 BDRVQEDState *s = acb_to_s(acb); 1074 uint64_t start = qed_start_of_cluster(s, acb->cur_pos); 1075 uint64_t len = qed_offset_into_cluster(s, acb->cur_pos); 1076 1077 trace_qed_aio_write_prefill(s, acb, start, len, acb->cur_cluster); 1078 qed_copy_from_backing_file(s, start, len, acb->cur_cluster, 1079 qed_aio_write_postfill, acb); 1080 } 1081 1082 /** 1083 * Check if the QED_F_NEED_CHECK bit should be set during allocating write 1084 */ 1085 static bool qed_should_set_need_check(BDRVQEDState *s) 1086 { 1087 /* The flush before L2 update path ensures consistency */ 1088 if (s->bs->backing_hd) { 1089 return false; 1090 } 1091 1092 return !(s->header.features & QED_F_NEED_CHECK); 1093 } 1094 1095 /** 1096 * Write new data cluster 1097 * 1098 * @acb: Write request 1099 * @len: Length in bytes 1100 * 1101 * This path is taken when writing to previously unallocated clusters. 1102 */ 1103 static void qed_aio_write_alloc(QEDAIOCB *acb, size_t len) 1104 { 1105 BDRVQEDState *s = acb_to_s(acb); 1106 1107 /* Cancel timer when the first allocating request comes in */ 1108 if (QSIMPLEQ_EMPTY(&s->allocating_write_reqs)) { 1109 qed_cancel_need_check_timer(s); 1110 } 1111 1112 /* Freeze this request if another allocating write is in progress */ 1113 if (acb != QSIMPLEQ_FIRST(&s->allocating_write_reqs)) { 1114 QSIMPLEQ_INSERT_TAIL(&s->allocating_write_reqs, acb, next); 1115 } 1116 if (acb != QSIMPLEQ_FIRST(&s->allocating_write_reqs) || 1117 s->allocating_write_reqs_plugged) { 1118 return; /* wait for existing request to finish */ 1119 } 1120 1121 acb->cur_nclusters = qed_bytes_to_clusters(s, 1122 qed_offset_into_cluster(s, acb->cur_pos) + len); 1123 acb->cur_cluster = qed_alloc_clusters(s, acb->cur_nclusters); 1124 qemu_iovec_copy(&acb->cur_qiov, acb->qiov, acb->qiov_offset, len); 1125 1126 if (qed_should_set_need_check(s)) { 1127 s->header.features |= QED_F_NEED_CHECK; 1128 qed_write_header(s, qed_aio_write_prefill, acb); 1129 } else { 1130 qed_aio_write_prefill(acb, 0); 1131 } 1132 } 1133 1134 /** 1135 * Write data cluster in place 1136 * 1137 * @acb: Write request 1138 * @offset: Cluster offset in bytes 1139 * @len: Length in bytes 1140 * 1141 * This path is taken when writing to already allocated clusters. 1142 */ 1143 static void qed_aio_write_inplace(QEDAIOCB *acb, uint64_t offset, size_t len) 1144 { 1145 /* Calculate the I/O vector */ 1146 acb->cur_cluster = offset; 1147 qemu_iovec_copy(&acb->cur_qiov, acb->qiov, acb->qiov_offset, len); 1148 1149 /* Do the actual write */ 1150 qed_aio_write_main(acb, 0); 1151 } 1152 1153 /** 1154 * Write data cluster 1155 * 1156 * @opaque: Write request 1157 * @ret: QED_CLUSTER_FOUND, QED_CLUSTER_L2, QED_CLUSTER_L1, 1158 * or -errno 1159 * @offset: Cluster offset in bytes 1160 * @len: Length in bytes 1161 * 1162 * Callback from qed_find_cluster(). 1163 */ 1164 static void qed_aio_write_data(void *opaque, int ret, 1165 uint64_t offset, size_t len) 1166 { 1167 QEDAIOCB *acb = opaque; 1168 1169 trace_qed_aio_write_data(acb_to_s(acb), acb, ret, offset, len); 1170 1171 acb->find_cluster_ret = ret; 1172 1173 switch (ret) { 1174 case QED_CLUSTER_FOUND: 1175 qed_aio_write_inplace(acb, offset, len); 1176 break; 1177 1178 case QED_CLUSTER_L2: 1179 case QED_CLUSTER_L1: 1180 case QED_CLUSTER_ZERO: 1181 qed_aio_write_alloc(acb, len); 1182 break; 1183 1184 default: 1185 qed_aio_complete(acb, ret); 1186 break; 1187 } 1188 } 1189 1190 /** 1191 * Read data cluster 1192 * 1193 * @opaque: Read request 1194 * @ret: QED_CLUSTER_FOUND, QED_CLUSTER_L2, QED_CLUSTER_L1, 1195 * or -errno 1196 * @offset: Cluster offset in bytes 1197 * @len: Length in bytes 1198 * 1199 * Callback from qed_find_cluster(). 1200 */ 1201 static void qed_aio_read_data(void *opaque, int ret, 1202 uint64_t offset, size_t len) 1203 { 1204 QEDAIOCB *acb = opaque; 1205 BDRVQEDState *s = acb_to_s(acb); 1206 BlockDriverState *bs = acb->common.bs; 1207 BlockDriverAIOCB *file_acb; 1208 1209 /* Adjust offset into cluster */ 1210 offset += qed_offset_into_cluster(s, acb->cur_pos); 1211 1212 trace_qed_aio_read_data(s, acb, ret, offset, len); 1213 1214 if (ret < 0) { 1215 goto err; 1216 } 1217 1218 qemu_iovec_copy(&acb->cur_qiov, acb->qiov, acb->qiov_offset, len); 1219 1220 /* Handle zero cluster and backing file reads */ 1221 if (ret == QED_CLUSTER_ZERO) { 1222 qemu_iovec_memset(&acb->cur_qiov, 0, acb->cur_qiov.size); 1223 qed_aio_next_io(acb, 0); 1224 return; 1225 } else if (ret != QED_CLUSTER_FOUND) { 1226 qed_read_backing_file(s, acb->cur_pos, &acb->cur_qiov, 1227 qed_aio_next_io, acb); 1228 return; 1229 } 1230 1231 BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO); 1232 file_acb = bdrv_aio_readv(bs->file, offset / BDRV_SECTOR_SIZE, 1233 &acb->cur_qiov, 1234 acb->cur_qiov.size / BDRV_SECTOR_SIZE, 1235 qed_aio_next_io, acb); 1236 if (!file_acb) { 1237 ret = -EIO; 1238 goto err; 1239 } 1240 return; 1241 1242 err: 1243 qed_aio_complete(acb, ret); 1244 } 1245 1246 /** 1247 * Begin next I/O or complete the request 1248 */ 1249 static void qed_aio_next_io(void *opaque, int ret) 1250 { 1251 QEDAIOCB *acb = opaque; 1252 BDRVQEDState *s = acb_to_s(acb); 1253 QEDFindClusterFunc *io_fn = 1254 acb->is_write ? qed_aio_write_data : qed_aio_read_data; 1255 1256 trace_qed_aio_next_io(s, acb, ret, acb->cur_pos + acb->cur_qiov.size); 1257 1258 /* Handle I/O error */ 1259 if (ret) { 1260 qed_aio_complete(acb, ret); 1261 return; 1262 } 1263 1264 acb->qiov_offset += acb->cur_qiov.size; 1265 acb->cur_pos += acb->cur_qiov.size; 1266 qemu_iovec_reset(&acb->cur_qiov); 1267 1268 /* Complete request */ 1269 if (acb->cur_pos >= acb->end_pos) { 1270 qed_aio_complete(acb, 0); 1271 return; 1272 } 1273 1274 /* Find next cluster and start I/O */ 1275 qed_find_cluster(s, &acb->request, 1276 acb->cur_pos, acb->end_pos - acb->cur_pos, 1277 io_fn, acb); 1278 } 1279 1280 static BlockDriverAIOCB *qed_aio_setup(BlockDriverState *bs, 1281 int64_t sector_num, 1282 QEMUIOVector *qiov, int nb_sectors, 1283 BlockDriverCompletionFunc *cb, 1284 void *opaque, bool is_write) 1285 { 1286 QEDAIOCB *acb = qemu_aio_get(&qed_aio_pool, bs, cb, opaque); 1287 1288 trace_qed_aio_setup(bs->opaque, acb, sector_num, nb_sectors, 1289 opaque, is_write); 1290 1291 acb->is_write = is_write; 1292 acb->finished = NULL; 1293 acb->qiov = qiov; 1294 acb->qiov_offset = 0; 1295 acb->cur_pos = (uint64_t)sector_num * BDRV_SECTOR_SIZE; 1296 acb->end_pos = acb->cur_pos + nb_sectors * BDRV_SECTOR_SIZE; 1297 acb->request.l2_table = NULL; 1298 qemu_iovec_init(&acb->cur_qiov, qiov->niov); 1299 1300 /* Start request */ 1301 qed_aio_next_io(acb, 0); 1302 return &acb->common; 1303 } 1304 1305 static BlockDriverAIOCB *bdrv_qed_aio_readv(BlockDriverState *bs, 1306 int64_t sector_num, 1307 QEMUIOVector *qiov, int nb_sectors, 1308 BlockDriverCompletionFunc *cb, 1309 void *opaque) 1310 { 1311 return qed_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, false); 1312 } 1313 1314 static BlockDriverAIOCB *bdrv_qed_aio_writev(BlockDriverState *bs, 1315 int64_t sector_num, 1316 QEMUIOVector *qiov, int nb_sectors, 1317 BlockDriverCompletionFunc *cb, 1318 void *opaque) 1319 { 1320 return qed_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, true); 1321 } 1322 1323 static BlockDriverAIOCB *bdrv_qed_aio_flush(BlockDriverState *bs, 1324 BlockDriverCompletionFunc *cb, 1325 void *opaque) 1326 { 1327 return bdrv_aio_flush(bs->file, cb, opaque); 1328 } 1329 1330 static int bdrv_qed_truncate(BlockDriverState *bs, int64_t offset) 1331 { 1332 BDRVQEDState *s = bs->opaque; 1333 uint64_t old_image_size; 1334 int ret; 1335 1336 if (!qed_is_image_size_valid(offset, s->header.cluster_size, 1337 s->header.table_size)) { 1338 return -EINVAL; 1339 } 1340 1341 /* Shrinking is currently not supported */ 1342 if ((uint64_t)offset < s->header.image_size) { 1343 return -ENOTSUP; 1344 } 1345 1346 old_image_size = s->header.image_size; 1347 s->header.image_size = offset; 1348 ret = qed_write_header_sync(s); 1349 if (ret < 0) { 1350 s->header.image_size = old_image_size; 1351 } 1352 return ret; 1353 } 1354 1355 static int64_t bdrv_qed_getlength(BlockDriverState *bs) 1356 { 1357 BDRVQEDState *s = bs->opaque; 1358 return s->header.image_size; 1359 } 1360 1361 static int bdrv_qed_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) 1362 { 1363 BDRVQEDState *s = bs->opaque; 1364 1365 memset(bdi, 0, sizeof(*bdi)); 1366 bdi->cluster_size = s->header.cluster_size; 1367 return 0; 1368 } 1369 1370 static int bdrv_qed_change_backing_file(BlockDriverState *bs, 1371 const char *backing_file, 1372 const char *backing_fmt) 1373 { 1374 BDRVQEDState *s = bs->opaque; 1375 QEDHeader new_header, le_header; 1376 void *buffer; 1377 size_t buffer_len, backing_file_len; 1378 int ret; 1379 1380 /* Refuse to set backing filename if unknown compat feature bits are 1381 * active. If the image uses an unknown compat feature then we may not 1382 * know the layout of data following the header structure and cannot safely 1383 * add a new string. 1384 */ 1385 if (backing_file && (s->header.compat_features & 1386 ~QED_COMPAT_FEATURE_MASK)) { 1387 return -ENOTSUP; 1388 } 1389 1390 memcpy(&new_header, &s->header, sizeof(new_header)); 1391 1392 new_header.features &= ~(QED_F_BACKING_FILE | 1393 QED_F_BACKING_FORMAT_NO_PROBE); 1394 1395 /* Adjust feature flags */ 1396 if (backing_file) { 1397 new_header.features |= QED_F_BACKING_FILE; 1398 1399 if (qed_fmt_is_raw(backing_fmt)) { 1400 new_header.features |= QED_F_BACKING_FORMAT_NO_PROBE; 1401 } 1402 } 1403 1404 /* Calculate new header size */ 1405 backing_file_len = 0; 1406 1407 if (backing_file) { 1408 backing_file_len = strlen(backing_file); 1409 } 1410 1411 buffer_len = sizeof(new_header); 1412 new_header.backing_filename_offset = buffer_len; 1413 new_header.backing_filename_size = backing_file_len; 1414 buffer_len += backing_file_len; 1415 1416 /* Make sure we can rewrite header without failing */ 1417 if (buffer_len > new_header.header_size * new_header.cluster_size) { 1418 return -ENOSPC; 1419 } 1420 1421 /* Prepare new header */ 1422 buffer = g_malloc(buffer_len); 1423 1424 qed_header_cpu_to_le(&new_header, &le_header); 1425 memcpy(buffer, &le_header, sizeof(le_header)); 1426 buffer_len = sizeof(le_header); 1427 1428 memcpy(buffer + buffer_len, backing_file, backing_file_len); 1429 buffer_len += backing_file_len; 1430 1431 /* Write new header */ 1432 ret = bdrv_pwrite_sync(bs->file, 0, buffer, buffer_len); 1433 g_free(buffer); 1434 if (ret == 0) { 1435 memcpy(&s->header, &new_header, sizeof(new_header)); 1436 } 1437 return ret; 1438 } 1439 1440 static int bdrv_qed_check(BlockDriverState *bs, BdrvCheckResult *result) 1441 { 1442 BDRVQEDState *s = bs->opaque; 1443 1444 return qed_check(s, result, false); 1445 } 1446 1447 static QEMUOptionParameter qed_create_options[] = { 1448 { 1449 .name = BLOCK_OPT_SIZE, 1450 .type = OPT_SIZE, 1451 .help = "Virtual disk size (in bytes)" 1452 }, { 1453 .name = BLOCK_OPT_BACKING_FILE, 1454 .type = OPT_STRING, 1455 .help = "File name of a base image" 1456 }, { 1457 .name = BLOCK_OPT_BACKING_FMT, 1458 .type = OPT_STRING, 1459 .help = "Image format of the base image" 1460 }, { 1461 .name = BLOCK_OPT_CLUSTER_SIZE, 1462 .type = OPT_SIZE, 1463 .help = "Cluster size (in bytes)", 1464 .value = { .n = QED_DEFAULT_CLUSTER_SIZE }, 1465 }, { 1466 .name = BLOCK_OPT_TABLE_SIZE, 1467 .type = OPT_SIZE, 1468 .help = "L1/L2 table size (in clusters)" 1469 }, 1470 { /* end of list */ } 1471 }; 1472 1473 static BlockDriver bdrv_qed = { 1474 .format_name = "qed", 1475 .instance_size = sizeof(BDRVQEDState), 1476 .create_options = qed_create_options, 1477 1478 .bdrv_probe = bdrv_qed_probe, 1479 .bdrv_open = bdrv_qed_open, 1480 .bdrv_close = bdrv_qed_close, 1481 .bdrv_create = bdrv_qed_create, 1482 .bdrv_flush = bdrv_qed_flush, 1483 .bdrv_is_allocated = bdrv_qed_is_allocated, 1484 .bdrv_make_empty = bdrv_qed_make_empty, 1485 .bdrv_aio_readv = bdrv_qed_aio_readv, 1486 .bdrv_aio_writev = bdrv_qed_aio_writev, 1487 .bdrv_aio_flush = bdrv_qed_aio_flush, 1488 .bdrv_truncate = bdrv_qed_truncate, 1489 .bdrv_getlength = bdrv_qed_getlength, 1490 .bdrv_get_info = bdrv_qed_get_info, 1491 .bdrv_change_backing_file = bdrv_qed_change_backing_file, 1492 .bdrv_check = bdrv_qed_check, 1493 }; 1494 1495 static void bdrv_qed_init(void) 1496 { 1497 bdrv_register(&bdrv_qed); 1498 } 1499 1500 block_init(bdrv_qed_init); 1501