1 /* 2 * QEMU System Emulator block driver 3 * 4 * Copyright (c) 2003 Fabrice Bellard 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to deal 8 * in the Software without restriction, including without limitation the rights 9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 10 * copies of the Software, and to permit persons to whom the Software is 11 * furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 22 * THE SOFTWARE. 23 */ 24 #ifndef BLOCK_INT_COMMON_H 25 #define BLOCK_INT_COMMON_H 26 27 #include "block/aio.h" 28 #include "block/block-common.h" 29 #include "block/block-global-state.h" 30 #include "block/snapshot.h" 31 #include "qemu/iov.h" 32 #include "qemu/rcu.h" 33 #include "qemu/stats64.h" 34 35 #define BLOCK_FLAG_LAZY_REFCOUNTS 8 36 37 #define BLOCK_OPT_SIZE "size" 38 #define BLOCK_OPT_ENCRYPT "encryption" 39 #define BLOCK_OPT_ENCRYPT_FORMAT "encrypt.format" 40 #define BLOCK_OPT_COMPAT6 "compat6" 41 #define BLOCK_OPT_HWVERSION "hwversion" 42 #define BLOCK_OPT_BACKING_FILE "backing_file" 43 #define BLOCK_OPT_BACKING_FMT "backing_fmt" 44 #define BLOCK_OPT_CLUSTER_SIZE "cluster_size" 45 #define BLOCK_OPT_TABLE_SIZE "table_size" 46 #define BLOCK_OPT_PREALLOC "preallocation" 47 #define BLOCK_OPT_SUBFMT "subformat" 48 #define BLOCK_OPT_COMPAT_LEVEL "compat" 49 #define BLOCK_OPT_LAZY_REFCOUNTS "lazy_refcounts" 50 #define BLOCK_OPT_ADAPTER_TYPE "adapter_type" 51 #define BLOCK_OPT_REDUNDANCY "redundancy" 52 #define BLOCK_OPT_NOCOW "nocow" 53 #define BLOCK_OPT_EXTENT_SIZE_HINT "extent_size_hint" 54 #define BLOCK_OPT_OBJECT_SIZE "object_size" 55 #define BLOCK_OPT_REFCOUNT_BITS "refcount_bits" 56 #define BLOCK_OPT_DATA_FILE "data_file" 57 #define BLOCK_OPT_DATA_FILE_RAW "data_file_raw" 58 #define BLOCK_OPT_COMPRESSION_TYPE "compression_type" 59 #define BLOCK_OPT_EXTL2 "extended_l2" 60 61 #define BLOCK_PROBE_BUF_SIZE 512 62 63 enum BdrvTrackedRequestType { 64 BDRV_TRACKED_READ, 65 BDRV_TRACKED_WRITE, 66 BDRV_TRACKED_DISCARD, 67 BDRV_TRACKED_TRUNCATE, 68 }; 69 70 /* 71 * That is not quite good that BdrvTrackedRequest structure is public, 72 * as block/io.c is very careful about incoming offset/bytes being 73 * correct. Be sure to assert bdrv_check_request() succeeded after any 74 * modification of BdrvTrackedRequest object out of block/io.c 75 */ 76 typedef struct BdrvTrackedRequest { 77 BlockDriverState *bs; 78 int64_t offset; 79 int64_t bytes; 80 enum BdrvTrackedRequestType type; 81 82 bool serialising; 83 int64_t overlap_offset; 84 int64_t overlap_bytes; 85 86 QLIST_ENTRY(BdrvTrackedRequest) list; 87 Coroutine *co; /* owner, used for deadlock detection */ 88 CoQueue wait_queue; /* coroutines blocked on this request */ 89 90 struct BdrvTrackedRequest *waiting_for; 91 } BdrvTrackedRequest; 92 93 94 struct BlockDriver { 95 /* 96 * These fields are initialized when this object is created, 97 * and are never changed afterwards. 98 */ 99 100 const char *format_name; 101 int instance_size; 102 103 /* 104 * Set to true if the BlockDriver is a block filter. Block filters pass 105 * certain callbacks that refer to data (see block.c) to their bs->file 106 * or bs->backing (whichever one exists) if the driver doesn't implement 107 * them. Drivers that do not wish to forward must implement them and return 108 * -ENOTSUP. 109 * Note that filters are not allowed to modify data. 110 * 111 * Filters generally cannot have more than a single filtered child, 112 * because the data they present must at all times be the same as 113 * that on their filtered child. That would be impossible to 114 * achieve for multiple filtered children. 115 * (And this filtered child must then be bs->file or bs->backing.) 116 */ 117 bool is_filter; 118 /* 119 * Only make sense for filter drivers, for others must be false. 120 * If true, filtered child is bs->backing. Otherwise it's bs->file. 121 * Two internal filters use bs->backing as filtered child and has this 122 * field set to true: mirror_top and commit_top. There also two such test 123 * filters in tests/unit/test-bdrv-graph-mod.c. 124 * 125 * Never create any more such filters! 126 * 127 * TODO: imagine how to deprecate this behavior and make all filters work 128 * similarly using bs->file as filtered child. 129 */ 130 bool filtered_child_is_backing; 131 132 /* 133 * Set to true if the BlockDriver is a format driver. Format nodes 134 * generally do not expect their children to be other format nodes 135 * (except for backing files), and so format probing is disabled 136 * on those children. 137 */ 138 bool is_format; 139 140 /* 141 * Drivers not implementing bdrv_parse_filename nor bdrv_open should have 142 * this field set to true, except ones that are defined only by their 143 * child's bs. 144 * An example of the last type will be the quorum block driver. 145 */ 146 bool bdrv_needs_filename; 147 148 /* 149 * Set if a driver can support backing files. This also implies the 150 * following semantics: 151 * 152 * - Return status 0 of .bdrv_co_block_status means that corresponding 153 * blocks are not allocated in this layer of backing-chain 154 * - For such (unallocated) blocks, read will: 155 * - fill buffer with zeros if there is no backing file 156 * - read from the backing file otherwise, where the block layer 157 * takes care of reading zeros beyond EOF if backing file is short 158 */ 159 bool supports_backing; 160 161 bool has_variable_length; 162 163 /* 164 * Drivers setting this field must be able to work with just a plain 165 * filename with '<protocol_name>:' as a prefix, and no other options. 166 * Options may be extracted from the filename by implementing 167 * bdrv_parse_filename. 168 */ 169 const char *protocol_name; 170 171 /* List of options for creating images, terminated by name == NULL */ 172 QemuOptsList *create_opts; 173 174 /* List of options for image amend */ 175 QemuOptsList *amend_opts; 176 177 /* 178 * If this driver supports reopening images this contains a 179 * NULL-terminated list of the runtime options that can be 180 * modified. If an option in this list is unspecified during 181 * reopen then it _must_ be reset to its default value or return 182 * an error. 183 */ 184 const char *const *mutable_opts; 185 186 /* 187 * Pointer to a NULL-terminated array of names of strong options 188 * that can be specified for bdrv_open(). A strong option is one 189 * that changes the data of a BDS. 190 * If this pointer is NULL, the array is considered empty. 191 * "filename" and "driver" are always considered strong. 192 */ 193 const char *const *strong_runtime_opts; 194 195 196 /* 197 * Global state (GS) API. These functions run under the BQL. 198 * 199 * See include/block/block-global-state.h for more information about 200 * the GS API. 201 */ 202 203 /* 204 * This function is invoked under BQL before .bdrv_co_amend() 205 * (which in contrast does not necessarily run under the BQL) 206 * to allow driver-specific initialization code that requires 207 * the BQL, like setting up specific permission flags. 208 */ 209 int (*bdrv_amend_pre_run)(BlockDriverState *bs, Error **errp); 210 /* 211 * This function is invoked under BQL after .bdrv_co_amend() 212 * to allow cleaning up what was done in .bdrv_amend_pre_run(). 213 */ 214 void (*bdrv_amend_clean)(BlockDriverState *bs); 215 216 /* 217 * Return true if @to_replace can be replaced by a BDS with the 218 * same data as @bs without it affecting @bs's behavior (that is, 219 * without it being visible to @bs's parents). 220 */ 221 bool (*bdrv_recurse_can_replace)(BlockDriverState *bs, 222 BlockDriverState *to_replace); 223 224 int (*bdrv_probe_device)(const char *filename); 225 226 /* 227 * Any driver implementing this callback is expected to be able to handle 228 * NULL file names in its .bdrv_open() implementation. 229 */ 230 void (*bdrv_parse_filename)(const char *filename, QDict *options, 231 Error **errp); 232 233 /* For handling image reopen for split or non-split files. */ 234 int (*bdrv_reopen_prepare)(BDRVReopenState *reopen_state, 235 BlockReopenQueue *queue, Error **errp); 236 void (*bdrv_reopen_commit)(BDRVReopenState *reopen_state); 237 void (*bdrv_reopen_commit_post)(BDRVReopenState *reopen_state); 238 void (*bdrv_reopen_abort)(BDRVReopenState *reopen_state); 239 void (*bdrv_join_options)(QDict *options, QDict *old_options); 240 241 int (*bdrv_open)(BlockDriverState *bs, QDict *options, int flags, 242 Error **errp); 243 244 /* Protocol drivers should implement this instead of bdrv_open */ 245 int (*bdrv_file_open)(BlockDriverState *bs, QDict *options, int flags, 246 Error **errp); 247 void (*bdrv_close)(BlockDriverState *bs); 248 249 int coroutine_fn (*bdrv_co_create)(BlockdevCreateOptions *opts, 250 Error **errp); 251 int coroutine_fn (*bdrv_co_create_opts)(BlockDriver *drv, 252 const char *filename, 253 QemuOpts *opts, 254 Error **errp); 255 256 int (*bdrv_amend_options)(BlockDriverState *bs, 257 QemuOpts *opts, 258 BlockDriverAmendStatusCB *status_cb, 259 void *cb_opaque, 260 bool force, 261 Error **errp); 262 263 int (*bdrv_make_empty)(BlockDriverState *bs); 264 265 /* 266 * Refreshes the bs->exact_filename field. If that is impossible, 267 * bs->exact_filename has to be left empty. 268 */ 269 void (*bdrv_refresh_filename)(BlockDriverState *bs); 270 271 /* 272 * Gathers the open options for all children into @target. 273 * A simple format driver (without backing file support) might 274 * implement this function like this: 275 * 276 * QINCREF(bs->file->bs->full_open_options); 277 * qdict_put(target, "file", bs->file->bs->full_open_options); 278 * 279 * If not specified, the generic implementation will simply put 280 * all children's options under their respective name. 281 * 282 * @backing_overridden is true when bs->backing seems not to be 283 * the child that would result from opening bs->backing_file. 284 * Therefore, if it is true, the backing child's options should be 285 * gathered; otherwise, there is no need since the backing child 286 * is the one implied by the image header. 287 * 288 * Note that ideally this function would not be needed. Every 289 * block driver which implements it is probably doing something 290 * shady regarding its runtime option structure. 291 */ 292 void (*bdrv_gather_child_options)(BlockDriverState *bs, QDict *target, 293 bool backing_overridden); 294 295 /* 296 * Returns an allocated string which is the directory name of this BDS: It 297 * will be used to make relative filenames absolute by prepending this 298 * function's return value to them. 299 */ 300 char *(*bdrv_dirname)(BlockDriverState *bs, Error **errp); 301 302 /* 303 * This informs the driver that we are no longer interested in the result 304 * of in-flight requests, so don't waste the time if possible. 305 * 306 * One example usage is to avoid waiting for an nbd target node reconnect 307 * timeout during job-cancel with force=true. 308 */ 309 void (*bdrv_cancel_in_flight)(BlockDriverState *bs); 310 311 int (*bdrv_inactivate)(BlockDriverState *bs); 312 313 int (*bdrv_snapshot_create)(BlockDriverState *bs, 314 QEMUSnapshotInfo *sn_info); 315 int (*bdrv_snapshot_goto)(BlockDriverState *bs, 316 const char *snapshot_id); 317 int (*bdrv_snapshot_delete)(BlockDriverState *bs, 318 const char *snapshot_id, 319 const char *name, 320 Error **errp); 321 int (*bdrv_snapshot_list)(BlockDriverState *bs, 322 QEMUSnapshotInfo **psn_info); 323 int (*bdrv_snapshot_load_tmp)(BlockDriverState *bs, 324 const char *snapshot_id, 325 const char *name, 326 Error **errp); 327 328 int (*bdrv_change_backing_file)(BlockDriverState *bs, 329 const char *backing_file, const char *backing_fmt); 330 331 /* TODO Better pass a option string/QDict/QemuOpts to add any rule? */ 332 int (*bdrv_debug_breakpoint)(BlockDriverState *bs, const char *event, 333 const char *tag); 334 int (*bdrv_debug_remove_breakpoint)(BlockDriverState *bs, 335 const char *tag); 336 int (*bdrv_debug_resume)(BlockDriverState *bs, const char *tag); 337 bool (*bdrv_debug_is_suspended)(BlockDriverState *bs, const char *tag); 338 339 void (*bdrv_refresh_limits)(BlockDriverState *bs, Error **errp); 340 341 /* 342 * Returns 1 if newly created images are guaranteed to contain only 343 * zeros, 0 otherwise. 344 */ 345 int (*bdrv_has_zero_init)(BlockDriverState *bs); 346 347 /* 348 * Remove fd handlers, timers, and other event loop callbacks so the event 349 * loop is no longer in use. Called with no in-flight requests and in 350 * depth-first traversal order with parents before child nodes. 351 */ 352 void (*bdrv_detach_aio_context)(BlockDriverState *bs); 353 354 /* 355 * Add fd handlers, timers, and other event loop callbacks so I/O requests 356 * can be processed again. Called with no in-flight requests and in 357 * depth-first traversal order with child nodes before parent nodes. 358 */ 359 void (*bdrv_attach_aio_context)(BlockDriverState *bs, 360 AioContext *new_context); 361 362 /** 363 * Try to get @bs's logical and physical block size. 364 * On success, store them in @bsz and return zero. 365 * On failure, return negative errno. 366 */ 367 int (*bdrv_probe_blocksizes)(BlockDriverState *bs, BlockSizes *bsz); 368 /** 369 * Try to get @bs's geometry (cyls, heads, sectors) 370 * On success, store them in @geo and return 0. 371 * On failure return -errno. 372 * Only drivers that want to override guest geometry implement this 373 * callback; see hd_geometry_guess(). 374 */ 375 int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo); 376 377 void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child, 378 Error **errp); 379 void (*bdrv_del_child)(BlockDriverState *parent, BdrvChild *child, 380 Error **errp); 381 382 /** 383 * Informs the block driver that a permission change is intended. The 384 * driver checks whether the change is permissible and may take other 385 * preparations for the change (e.g. get file system locks). This operation 386 * is always followed either by a call to either .bdrv_set_perm or 387 * .bdrv_abort_perm_update. 388 * 389 * Checks whether the requested set of cumulative permissions in @perm 390 * can be granted for accessing @bs and whether no other users are using 391 * permissions other than those given in @shared (both arguments take 392 * BLK_PERM_* bitmasks). 393 * 394 * If both conditions are met, 0 is returned. Otherwise, -errno is returned 395 * and errp is set to an error describing the conflict. 396 */ 397 int (*bdrv_check_perm)(BlockDriverState *bs, uint64_t perm, 398 uint64_t shared, Error **errp); 399 400 /** 401 * Called to inform the driver that the set of cumulative set of used 402 * permissions for @bs has changed to @perm, and the set of sharable 403 * permission to @shared. The driver can use this to propagate changes to 404 * its children (i.e. request permissions only if a parent actually needs 405 * them). 406 * 407 * This function is only invoked after bdrv_check_perm(), so block drivers 408 * may rely on preparations made in their .bdrv_check_perm implementation. 409 */ 410 void (*bdrv_set_perm)(BlockDriverState *bs, uint64_t perm, uint64_t shared); 411 412 /* 413 * Called to inform the driver that after a previous bdrv_check_perm() 414 * call, the permission update is not performed and any preparations made 415 * for it (e.g. taken file locks) need to be undone. 416 * 417 * This function can be called even for nodes that never saw a 418 * bdrv_check_perm() call. It is a no-op then. 419 */ 420 void (*bdrv_abort_perm_update)(BlockDriverState *bs); 421 422 /** 423 * Returns in @nperm and @nshared the permissions that the driver for @bs 424 * needs on its child @c, based on the cumulative permissions requested by 425 * the parents in @parent_perm and @parent_shared. 426 * 427 * If @c is NULL, return the permissions for attaching a new child for the 428 * given @child_class and @role. 429 * 430 * If @reopen_queue is non-NULL, don't return the currently needed 431 * permissions, but those that will be needed after applying the 432 * @reopen_queue. 433 */ 434 void (*bdrv_child_perm)(BlockDriverState *bs, BdrvChild *c, 435 BdrvChildRole role, 436 BlockReopenQueue *reopen_queue, 437 uint64_t parent_perm, uint64_t parent_shared, 438 uint64_t *nperm, uint64_t *nshared); 439 440 /** 441 * Register/unregister a buffer for I/O. For example, when the driver is 442 * interested to know the memory areas that will later be used in iovs, so 443 * that it can do IOMMU mapping with VFIO etc., in order to get better 444 * performance. In the case of VFIO drivers, this callback is used to do 445 * DMA mapping for hot buffers. 446 * 447 * Returns: true on success, false on failure 448 */ 449 bool (*bdrv_register_buf)(BlockDriverState *bs, void *host, size_t size, 450 Error **errp); 451 void (*bdrv_unregister_buf)(BlockDriverState *bs, void *host, size_t size); 452 453 /* 454 * This field is modified only under the BQL, and is part of 455 * the global state. 456 */ 457 QLIST_ENTRY(BlockDriver) list; 458 459 /* 460 * I/O API functions. These functions are thread-safe. 461 * 462 * See include/block/block-io.h for more information about 463 * the I/O API. 464 */ 465 466 int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename); 467 468 int coroutine_fn (*bdrv_co_amend)(BlockDriverState *bs, 469 BlockdevAmendOptions *opts, 470 bool force, 471 Error **errp); 472 473 /* aio */ 474 BlockAIOCB *(*bdrv_aio_preadv)(BlockDriverState *bs, 475 int64_t offset, int64_t bytes, QEMUIOVector *qiov, 476 BdrvRequestFlags flags, BlockCompletionFunc *cb, void *opaque); 477 BlockAIOCB *(*bdrv_aio_pwritev)(BlockDriverState *bs, 478 int64_t offset, int64_t bytes, QEMUIOVector *qiov, 479 BdrvRequestFlags flags, BlockCompletionFunc *cb, void *opaque); 480 BlockAIOCB *(*bdrv_aio_flush)(BlockDriverState *bs, 481 BlockCompletionFunc *cb, void *opaque); 482 BlockAIOCB *(*bdrv_aio_pdiscard)(BlockDriverState *bs, 483 int64_t offset, int bytes, 484 BlockCompletionFunc *cb, void *opaque); 485 486 int coroutine_fn (*bdrv_co_readv)(BlockDriverState *bs, 487 int64_t sector_num, int nb_sectors, QEMUIOVector *qiov); 488 489 /** 490 * @offset: position in bytes to read at 491 * @bytes: number of bytes to read 492 * @qiov: the buffers to fill with read data 493 * @flags: currently unused, always 0 494 * 495 * @offset and @bytes will be a multiple of 'request_alignment', 496 * but the length of individual @qiov elements does not have to 497 * be a multiple. 498 * 499 * @bytes will always equal the total size of @qiov, and will be 500 * no larger than 'max_transfer'. 501 * 502 * The buffer in @qiov may point directly to guest memory. 503 */ 504 int coroutine_fn (*bdrv_co_preadv)(BlockDriverState *bs, 505 int64_t offset, int64_t bytes, QEMUIOVector *qiov, 506 BdrvRequestFlags flags); 507 508 int coroutine_fn (*bdrv_co_preadv_part)(BlockDriverState *bs, 509 int64_t offset, int64_t bytes, 510 QEMUIOVector *qiov, size_t qiov_offset, 511 BdrvRequestFlags flags); 512 513 int coroutine_fn (*bdrv_co_writev)(BlockDriverState *bs, 514 int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, 515 int flags); 516 /** 517 * @offset: position in bytes to write at 518 * @bytes: number of bytes to write 519 * @qiov: the buffers containing data to write 520 * @flags: zero or more bits allowed by 'supported_write_flags' 521 * 522 * @offset and @bytes will be a multiple of 'request_alignment', 523 * but the length of individual @qiov elements does not have to 524 * be a multiple. 525 * 526 * @bytes will always equal the total size of @qiov, and will be 527 * no larger than 'max_transfer'. 528 * 529 * The buffer in @qiov may point directly to guest memory. 530 */ 531 int coroutine_fn (*bdrv_co_pwritev)(BlockDriverState *bs, 532 int64_t offset, int64_t bytes, QEMUIOVector *qiov, 533 BdrvRequestFlags flags); 534 int coroutine_fn (*bdrv_co_pwritev_part)(BlockDriverState *bs, 535 int64_t offset, int64_t bytes, QEMUIOVector *qiov, size_t qiov_offset, 536 BdrvRequestFlags flags); 537 538 /* 539 * Efficiently zero a region of the disk image. Typically an image format 540 * would use a compact metadata representation to implement this. This 541 * function pointer may be NULL or return -ENOSUP and .bdrv_co_writev() 542 * will be called instead. 543 */ 544 int coroutine_fn (*bdrv_co_pwrite_zeroes)(BlockDriverState *bs, 545 int64_t offset, int64_t bytes, BdrvRequestFlags flags); 546 int coroutine_fn (*bdrv_co_pdiscard)(BlockDriverState *bs, 547 int64_t offset, int64_t bytes); 548 549 /* 550 * Map [offset, offset + nbytes) range onto a child of @bs to copy from, 551 * and invoke bdrv_co_copy_range_from(child, ...), or invoke 552 * bdrv_co_copy_range_to() if @bs is the leaf child to copy data from. 553 * 554 * See the comment of bdrv_co_copy_range for the parameter and return value 555 * semantics. 556 */ 557 int coroutine_fn (*bdrv_co_copy_range_from)(BlockDriverState *bs, 558 BdrvChild *src, 559 int64_t offset, 560 BdrvChild *dst, 561 int64_t dst_offset, 562 int64_t bytes, 563 BdrvRequestFlags read_flags, 564 BdrvRequestFlags write_flags); 565 566 /* 567 * Map [offset, offset + nbytes) range onto a child of bs to copy data to, 568 * and invoke bdrv_co_copy_range_to(child, src, ...), or perform the copy 569 * operation if @bs is the leaf and @src has the same BlockDriver. Return 570 * -ENOTSUP if @bs is the leaf but @src has a different BlockDriver. 571 * 572 * See the comment of bdrv_co_copy_range for the parameter and return value 573 * semantics. 574 */ 575 int coroutine_fn (*bdrv_co_copy_range_to)(BlockDriverState *bs, 576 BdrvChild *src, 577 int64_t src_offset, 578 BdrvChild *dst, 579 int64_t dst_offset, 580 int64_t bytes, 581 BdrvRequestFlags read_flags, 582 BdrvRequestFlags write_flags); 583 584 /* 585 * Building block for bdrv_block_status[_above] and 586 * bdrv_is_allocated[_above]. The driver should answer only 587 * according to the current layer, and should only need to set 588 * BDRV_BLOCK_DATA, BDRV_BLOCK_ZERO, BDRV_BLOCK_OFFSET_VALID, 589 * and/or BDRV_BLOCK_RAW; if the current layer defers to a backing 590 * layer, the result should be 0 (and not BDRV_BLOCK_ZERO). See 591 * block.h for the overall meaning of the bits. As a hint, the 592 * flag want_zero is true if the caller cares more about precise 593 * mappings (favor accurate _OFFSET_VALID/_ZERO) or false for 594 * overall allocation (favor larger *pnum, perhaps by reporting 595 * _DATA instead of _ZERO). The block layer guarantees input 596 * clamped to bdrv_getlength() and aligned to request_alignment, 597 * as well as non-NULL pnum, map, and file; in turn, the driver 598 * must return an error or set pnum to an aligned non-zero value. 599 * 600 * Note that @bytes is just a hint on how big of a region the 601 * caller wants to inspect. It is not a limit on *pnum. 602 * Implementations are free to return larger values of *pnum if 603 * doing so does not incur a performance penalty. 604 * 605 * block/io.c's bdrv_co_block_status() will utilize an unclamped 606 * *pnum value for the block-status cache on protocol nodes, prior 607 * to clamping *pnum for return to its caller. 608 */ 609 int coroutine_fn (*bdrv_co_block_status)(BlockDriverState *bs, 610 bool want_zero, int64_t offset, int64_t bytes, int64_t *pnum, 611 int64_t *map, BlockDriverState **file); 612 613 /* 614 * Snapshot-access API. 615 * 616 * Block-driver may provide snapshot-access API: special functions to access 617 * some internal "snapshot". The functions are similar with normal 618 * read/block_status/discard handler, but don't have any specific handling 619 * in generic block-layer: no serializing, no alignment, no tracked 620 * requests. So, block-driver that realizes these APIs is fully responsible 621 * for synchronization between snapshot-access API and normal IO requests. 622 * 623 * TODO: To be able to support qcow2's internal snapshots, this API will 624 * need to be extended to: 625 * - be able to select a specific snapshot 626 * - receive the snapshot's actual length (which may differ from bs's 627 * length) 628 */ 629 int coroutine_fn (*bdrv_co_preadv_snapshot)(BlockDriverState *bs, 630 int64_t offset, int64_t bytes, QEMUIOVector *qiov, size_t qiov_offset); 631 int coroutine_fn (*bdrv_co_snapshot_block_status)(BlockDriverState *bs, 632 bool want_zero, int64_t offset, int64_t bytes, int64_t *pnum, 633 int64_t *map, BlockDriverState **file); 634 int coroutine_fn (*bdrv_co_pdiscard_snapshot)(BlockDriverState *bs, 635 int64_t offset, int64_t bytes); 636 637 /* 638 * Invalidate any cached meta-data. 639 */ 640 void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_invalidate_cache)( 641 BlockDriverState *bs, Error **errp); 642 643 /* 644 * Flushes all data for all layers by calling bdrv_co_flush for underlying 645 * layers, if needed. This function is needed for deterministic 646 * synchronization of the flush finishing callback. 647 */ 648 int coroutine_fn (*bdrv_co_flush)(BlockDriverState *bs); 649 650 /* Delete a created file. */ 651 int coroutine_fn (*bdrv_co_delete_file)(BlockDriverState *bs, 652 Error **errp); 653 654 /* 655 * Flushes all data that was already written to the OS all the way down to 656 * the disk (for example file-posix.c calls fsync()). 657 */ 658 int coroutine_fn (*bdrv_co_flush_to_disk)(BlockDriverState *bs); 659 660 /* 661 * Flushes all internal caches to the OS. The data may still sit in a 662 * writeback cache of the host OS, but it will survive a crash of the qemu 663 * process. 664 */ 665 int coroutine_fn (*bdrv_co_flush_to_os)(BlockDriverState *bs); 666 667 /* 668 * Truncate @bs to @offset bytes using the given @prealloc mode 669 * when growing. Modes other than PREALLOC_MODE_OFF should be 670 * rejected when shrinking @bs. 671 * 672 * If @exact is true, @bs must be resized to exactly @offset. 673 * Otherwise, it is sufficient for @bs (if it is a host block 674 * device and thus there is no way to resize it) to be at least 675 * @offset bytes in length. 676 * 677 * If @exact is true and this function fails but would succeed 678 * with @exact = false, it should return -ENOTSUP. 679 */ 680 int coroutine_fn (*bdrv_co_truncate)(BlockDriverState *bs, int64_t offset, 681 bool exact, PreallocMode prealloc, 682 BdrvRequestFlags flags, Error **errp); 683 int64_t (*bdrv_getlength)(BlockDriverState *bs); 684 int64_t (*bdrv_get_allocated_file_size)(BlockDriverState *bs); 685 BlockMeasureInfo *(*bdrv_measure)(QemuOpts *opts, BlockDriverState *in_bs, 686 Error **errp); 687 688 int coroutine_fn (*bdrv_co_pwritev_compressed)(BlockDriverState *bs, 689 int64_t offset, int64_t bytes, QEMUIOVector *qiov); 690 int coroutine_fn (*bdrv_co_pwritev_compressed_part)(BlockDriverState *bs, 691 int64_t offset, int64_t bytes, QEMUIOVector *qiov, 692 size_t qiov_offset); 693 694 int (*bdrv_get_info)(BlockDriverState *bs, BlockDriverInfo *bdi); 695 696 ImageInfoSpecific *(*bdrv_get_specific_info)(BlockDriverState *bs, 697 Error **errp); 698 BlockStatsSpecific *(*bdrv_get_specific_stats)(BlockDriverState *bs); 699 700 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_save_vmstate)( 701 BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos); 702 703 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_load_vmstate)( 704 BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos); 705 706 /* removable device specific */ 707 bool (*bdrv_is_inserted)(BlockDriverState *bs); 708 void (*bdrv_eject)(BlockDriverState *bs, bool eject_flag); 709 void (*bdrv_lock_medium)(BlockDriverState *bs, bool locked); 710 711 /* to control generic scsi devices */ 712 BlockAIOCB *(*bdrv_aio_ioctl)(BlockDriverState *bs, 713 unsigned long int req, void *buf, 714 BlockCompletionFunc *cb, void *opaque); 715 int coroutine_fn (*bdrv_co_ioctl)(BlockDriverState *bs, 716 unsigned long int req, void *buf); 717 718 /* 719 * Returns 0 for completed check, -errno for internal errors. 720 * The check results are stored in result. 721 */ 722 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_check)( 723 BlockDriverState *bs, BdrvCheckResult *result, BdrvCheckMode fix); 724 725 void (*bdrv_debug_event)(BlockDriverState *bs, BlkdebugEvent event); 726 727 /* io queue for linux-aio */ 728 void (*bdrv_io_plug)(BlockDriverState *bs); 729 void (*bdrv_io_unplug)(BlockDriverState *bs); 730 731 /** 732 * bdrv_drain_begin is called if implemented in the beginning of a 733 * drain operation to drain and stop any internal sources of requests in 734 * the driver. 735 * bdrv_drain_end is called if implemented at the end of the drain. 736 * 737 * They should be used by the driver to e.g. manage scheduled I/O 738 * requests, or toggle an internal state. After the end of the drain new 739 * requests will continue normally. 740 * 741 * Implementations of both functions must not call aio_poll(). 742 */ 743 void (*bdrv_drain_begin)(BlockDriverState *bs); 744 void (*bdrv_drain_end)(BlockDriverState *bs); 745 746 bool (*bdrv_supports_persistent_dirty_bitmap)(BlockDriverState *bs); 747 bool coroutine_fn (*bdrv_co_can_store_new_dirty_bitmap)( 748 BlockDriverState *bs, const char *name, uint32_t granularity, 749 Error **errp); 750 int coroutine_fn (*bdrv_co_remove_persistent_dirty_bitmap)( 751 BlockDriverState *bs, const char *name, Error **errp); 752 }; 753 754 static inline bool block_driver_can_compress(BlockDriver *drv) 755 { 756 return drv->bdrv_co_pwritev_compressed || 757 drv->bdrv_co_pwritev_compressed_part; 758 } 759 760 typedef struct BlockLimits { 761 /* 762 * Alignment requirement, in bytes, for offset/length of I/O 763 * requests. Must be a power of 2 less than INT_MAX; defaults to 764 * 1 for drivers with modern byte interfaces, and to 512 765 * otherwise. 766 */ 767 uint32_t request_alignment; 768 769 /* 770 * Maximum number of bytes that can be discarded at once. Must be multiple 771 * of pdiscard_alignment, but need not be power of 2. May be 0 if no 772 * inherent 64-bit limit. 773 */ 774 int64_t max_pdiscard; 775 776 /* 777 * Optimal alignment for discard requests in bytes. A power of 2 778 * is best but not mandatory. Must be a multiple of 779 * bl.request_alignment, and must be less than max_pdiscard if 780 * that is set. May be 0 if bl.request_alignment is good enough 781 */ 782 uint32_t pdiscard_alignment; 783 784 /* 785 * Maximum number of bytes that can zeroized at once. Must be multiple of 786 * pwrite_zeroes_alignment. 0 means no limit. 787 */ 788 int64_t max_pwrite_zeroes; 789 790 /* 791 * Optimal alignment for write zeroes requests in bytes. A power 792 * of 2 is best but not mandatory. Must be a multiple of 793 * bl.request_alignment, and must be less than max_pwrite_zeroes 794 * if that is set. May be 0 if bl.request_alignment is good 795 * enough 796 */ 797 uint32_t pwrite_zeroes_alignment; 798 799 /* 800 * Optimal transfer length in bytes. A power of 2 is best but not 801 * mandatory. Must be a multiple of bl.request_alignment, or 0 if 802 * no preferred size 803 */ 804 uint32_t opt_transfer; 805 806 /* 807 * Maximal transfer length in bytes. Need not be power of 2, but 808 * must be multiple of opt_transfer and bl.request_alignment, or 0 809 * for no 32-bit limit. For now, anything larger than INT_MAX is 810 * clamped down. 811 */ 812 uint32_t max_transfer; 813 814 /* 815 * Maximal hardware transfer length in bytes. Applies whenever 816 * transfers to the device bypass the kernel I/O scheduler, for 817 * example with SG_IO. If larger than max_transfer or if zero, 818 * blk_get_max_hw_transfer will fall back to max_transfer. 819 */ 820 uint64_t max_hw_transfer; 821 822 /* 823 * Maximal number of scatter/gather elements allowed by the hardware. 824 * Applies whenever transfers to the device bypass the kernel I/O 825 * scheduler, for example with SG_IO. If larger than max_iov 826 * or if zero, blk_get_max_hw_iov will fall back to max_iov. 827 */ 828 int max_hw_iov; 829 830 831 /* memory alignment, in bytes so that no bounce buffer is needed */ 832 size_t min_mem_alignment; 833 834 /* memory alignment, in bytes, for bounce buffer */ 835 size_t opt_mem_alignment; 836 837 /* maximum number of iovec elements */ 838 int max_iov; 839 } BlockLimits; 840 841 typedef struct BdrvOpBlocker BdrvOpBlocker; 842 843 typedef struct BdrvAioNotifier { 844 void (*attached_aio_context)(AioContext *new_context, void *opaque); 845 void (*detach_aio_context)(void *opaque); 846 847 void *opaque; 848 bool deleted; 849 850 QLIST_ENTRY(BdrvAioNotifier) list; 851 } BdrvAioNotifier; 852 853 struct BdrvChildClass { 854 /* 855 * If true, bdrv_replace_node() doesn't change the node this BdrvChild 856 * points to. 857 */ 858 bool stay_at_node; 859 860 /* 861 * If true, the parent is a BlockDriverState and bdrv_next_all_states() 862 * will return it. This information is used for drain_all, where every node 863 * will be drained separately, so the drain only needs to be propagated to 864 * non-BDS parents. 865 */ 866 bool parent_is_bds; 867 868 /* 869 * Global state (GS) API. These functions run under the BQL. 870 * 871 * See include/block/block-global-state.h for more information about 872 * the GS API. 873 */ 874 void (*inherit_options)(BdrvChildRole role, bool parent_is_format, 875 int *child_flags, QDict *child_options, 876 int parent_flags, QDict *parent_options); 877 void (*change_media)(BdrvChild *child, bool load); 878 879 /* 880 * Returns a malloced string that describes the parent of the child for a 881 * human reader. This could be a node-name, BlockBackend name, qdev ID or 882 * QOM path of the device owning the BlockBackend, job type and ID etc. The 883 * caller is responsible for freeing the memory. 884 */ 885 char *(*get_parent_desc)(BdrvChild *child); 886 887 /* 888 * Notifies the parent that the child has been activated/inactivated (e.g. 889 * when migration is completing) and it can start/stop requesting 890 * permissions and doing I/O on it. 891 */ 892 void (*activate)(BdrvChild *child, Error **errp); 893 int (*inactivate)(BdrvChild *child); 894 895 void GRAPH_WRLOCK_PTR (*attach)(BdrvChild *child); 896 void GRAPH_WRLOCK_PTR (*detach)(BdrvChild *child); 897 898 /* 899 * Notifies the parent that the filename of its child has changed (e.g. 900 * because the direct child was removed from the backing chain), so that it 901 * can update its reference. 902 */ 903 int (*update_filename)(BdrvChild *child, BlockDriverState *new_base, 904 const char *filename, Error **errp); 905 906 bool (*change_aio_ctx)(BdrvChild *child, AioContext *ctx, 907 GHashTable *visited, Transaction *tran, 908 Error **errp); 909 910 /* 911 * I/O API functions. These functions are thread-safe. 912 * 913 * See include/block/block-io.h for more information about 914 * the I/O API. 915 */ 916 917 void (*resize)(BdrvChild *child); 918 919 /* 920 * Returns a name that is supposedly more useful for human users than the 921 * node name for identifying the node in question (in particular, a BB 922 * name), or NULL if the parent can't provide a better name. 923 */ 924 const char *(*get_name)(BdrvChild *child); 925 926 AioContext *(*get_parent_aio_context)(BdrvChild *child); 927 928 /* 929 * If this pair of functions is implemented, the parent doesn't issue new 930 * requests after returning from .drained_begin() until .drained_end() is 931 * called. 932 * 933 * These functions must not change the graph (and therefore also must not 934 * call aio_poll(), which could change the graph indirectly). 935 * 936 * Note that this can be nested. If drained_begin() was called twice, new 937 * I/O is allowed only after drained_end() was called twice, too. 938 */ 939 void (*drained_begin)(BdrvChild *child); 940 void (*drained_end)(BdrvChild *child); 941 942 /* 943 * Returns whether the parent has pending requests for the child. This 944 * callback is polled after .drained_begin() has been called until all 945 * activity on the child has stopped. 946 */ 947 bool (*drained_poll)(BdrvChild *child); 948 }; 949 950 extern const BdrvChildClass child_of_bds; 951 952 struct BdrvChild { 953 BlockDriverState *bs; 954 char *name; 955 const BdrvChildClass *klass; 956 BdrvChildRole role; 957 void *opaque; 958 959 /** 960 * Granted permissions for operating on this BdrvChild (BLK_PERM_* bitmask) 961 */ 962 uint64_t perm; 963 964 /** 965 * Permissions that can still be granted to other users of @bs while this 966 * BdrvChild is still attached to it. (BLK_PERM_* bitmask) 967 */ 968 uint64_t shared_perm; 969 970 /* 971 * This link is frozen: the child can neither be replaced nor 972 * detached from the parent. 973 */ 974 bool frozen; 975 976 /* 977 * True if the parent of this child has been drained by this BdrvChild 978 * (through klass->drained_*). 979 * 980 * It is generally true if bs->quiesce_counter > 0. It may differ while the 981 * child is entering or leaving a drained section. 982 */ 983 bool quiesced_parent; 984 985 QLIST_ENTRY(BdrvChild) next; 986 QLIST_ENTRY(BdrvChild) next_parent; 987 }; 988 989 /* 990 * Allows bdrv_co_block_status() to cache one data region for a 991 * protocol node. 992 * 993 * @valid: Whether the cache is valid (should be accessed with atomic 994 * functions so this can be reset by RCU readers) 995 * @data_start: Offset where we know (or strongly assume) is data 996 * @data_end: Offset where the data region ends (which is not necessarily 997 * the start of a zeroed region) 998 */ 999 typedef struct BdrvBlockStatusCache { 1000 struct rcu_head rcu; 1001 1002 bool valid; 1003 int64_t data_start; 1004 int64_t data_end; 1005 } BdrvBlockStatusCache; 1006 1007 struct BlockDriverState { 1008 /* 1009 * Protected by big QEMU lock or read-only after opening. No special 1010 * locking needed during I/O... 1011 */ 1012 int open_flags; /* flags used to open the file, re-used for re-open */ 1013 bool encrypted; /* if true, the media is encrypted */ 1014 bool sg; /* if true, the device is a /dev/sg* */ 1015 bool probed; /* if true, format was probed rather than specified */ 1016 bool force_share; /* if true, always allow all shared permissions */ 1017 bool implicit; /* if true, this filter node was automatically inserted */ 1018 1019 BlockDriver *drv; /* NULL means no media */ 1020 void *opaque; 1021 1022 AioContext *aio_context; /* event loop used for fd handlers, timers, etc */ 1023 /* 1024 * long-running tasks intended to always use the same AioContext as this 1025 * BDS may register themselves in this list to be notified of changes 1026 * regarding this BDS's context 1027 */ 1028 QLIST_HEAD(, BdrvAioNotifier) aio_notifiers; 1029 bool walking_aio_notifiers; /* to make removal during iteration safe */ 1030 1031 char filename[PATH_MAX]; 1032 /* 1033 * If not empty, this image is a diff in relation to backing_file. 1034 * Note that this is the name given in the image header and 1035 * therefore may or may not be equal to .backing->bs->filename. 1036 * If this field contains a relative path, it is to be resolved 1037 * relatively to the overlay's location. 1038 */ 1039 char backing_file[PATH_MAX]; 1040 /* 1041 * The backing filename indicated by the image header. Contrary 1042 * to backing_file, if we ever open this file, auto_backing_file 1043 * is replaced by the resulting BDS's filename (i.e. after a 1044 * bdrv_refresh_filename() run). 1045 */ 1046 char auto_backing_file[PATH_MAX]; 1047 char backing_format[16]; /* if non-zero and backing_file exists */ 1048 1049 QDict *full_open_options; 1050 char exact_filename[PATH_MAX]; 1051 1052 /* I/O Limits */ 1053 BlockLimits bl; 1054 1055 /* 1056 * Flags honored during pread 1057 */ 1058 BdrvRequestFlags supported_read_flags; 1059 /* 1060 * Flags honored during pwrite (so far: BDRV_REQ_FUA, 1061 * BDRV_REQ_WRITE_UNCHANGED). 1062 * If a driver does not support BDRV_REQ_WRITE_UNCHANGED, those 1063 * writes will be issued as normal writes without the flag set. 1064 * This is important to note for drivers that do not explicitly 1065 * request a WRITE permission for their children and instead take 1066 * the same permissions as their parent did (this is commonly what 1067 * block filters do). Such drivers have to be aware that the 1068 * parent may have taken a WRITE_UNCHANGED permission only and is 1069 * issuing such requests. Drivers either must make sure that 1070 * these requests do not result in plain WRITE accesses (usually 1071 * by supporting BDRV_REQ_WRITE_UNCHANGED, and then forwarding 1072 * every incoming write request as-is, including potentially that 1073 * flag), or they have to explicitly take the WRITE permission for 1074 * their children. 1075 */ 1076 BdrvRequestFlags supported_write_flags; 1077 /* 1078 * Flags honored during pwrite_zeroes (so far: BDRV_REQ_FUA, 1079 * BDRV_REQ_MAY_UNMAP, BDRV_REQ_WRITE_UNCHANGED) 1080 */ 1081 BdrvRequestFlags supported_zero_flags; 1082 /* 1083 * Flags honoured during truncate (so far: BDRV_REQ_ZERO_WRITE). 1084 * 1085 * If BDRV_REQ_ZERO_WRITE is given, the truncate operation must make sure 1086 * that any added space reads as all zeros. If this can't be guaranteed, 1087 * the operation must fail. 1088 */ 1089 BdrvRequestFlags supported_truncate_flags; 1090 1091 /* the following member gives a name to every node on the bs graph. */ 1092 char node_name[32]; 1093 /* element of the list of named nodes building the graph */ 1094 QTAILQ_ENTRY(BlockDriverState) node_list; 1095 /* element of the list of all BlockDriverStates (all_bdrv_states) */ 1096 QTAILQ_ENTRY(BlockDriverState) bs_list; 1097 /* element of the list of monitor-owned BDS */ 1098 QTAILQ_ENTRY(BlockDriverState) monitor_list; 1099 int refcnt; 1100 1101 /* operation blockers. Protected by BQL. */ 1102 QLIST_HEAD(, BdrvOpBlocker) op_blockers[BLOCK_OP_TYPE_MAX]; 1103 1104 /* 1105 * The node that this node inherited default options from (and a reopen on 1106 * which can affect this node by changing these defaults). This is always a 1107 * parent node of this node. 1108 */ 1109 BlockDriverState *inherits_from; 1110 1111 /* 1112 * @backing and @file are some of @children or NULL. All these three fields 1113 * (@file, @backing and @children) are modified only in 1114 * bdrv_child_cb_attach() and bdrv_child_cb_detach(). 1115 * 1116 * See also comment in include/block/block.h, to learn how backing and file 1117 * are connected with BdrvChildRole. 1118 */ 1119 QLIST_HEAD(, BdrvChild) children; 1120 BdrvChild *backing; 1121 BdrvChild *file; 1122 1123 QLIST_HEAD(, BdrvChild) parents; 1124 1125 QDict *options; 1126 QDict *explicit_options; 1127 BlockdevDetectZeroesOptions detect_zeroes; 1128 1129 /* The error object in use for blocking operations on backing_hd */ 1130 Error *backing_blocker; 1131 1132 /* Protected by AioContext lock */ 1133 1134 /* 1135 * If we are reading a disk image, give its size in sectors. 1136 * Generally read-only; it is written to by load_snapshot and 1137 * save_snaphost, but the block layer is quiescent during those. 1138 */ 1139 int64_t total_sectors; 1140 1141 /* threshold limit for writes, in bytes. "High water mark". */ 1142 uint64_t write_threshold_offset; 1143 1144 /* 1145 * Writing to the list requires the BQL _and_ the dirty_bitmap_mutex. 1146 * Reading from the list can be done with either the BQL or the 1147 * dirty_bitmap_mutex. Modifying a bitmap only requires 1148 * dirty_bitmap_mutex. 1149 */ 1150 QemuMutex dirty_bitmap_mutex; 1151 QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps; 1152 1153 /* Offset after the highest byte written to */ 1154 Stat64 wr_highest_offset; 1155 1156 /* 1157 * If true, copy read backing sectors into image. Can be >1 if more 1158 * than one client has requested copy-on-read. Accessed with atomic 1159 * ops. 1160 */ 1161 int copy_on_read; 1162 1163 /* 1164 * number of in-flight requests; overall and serialising. 1165 * Accessed with atomic ops. 1166 */ 1167 unsigned int in_flight; 1168 unsigned int serialising_in_flight; 1169 1170 /* 1171 * counter for nested bdrv_io_plug. 1172 * Accessed with atomic ops. 1173 */ 1174 unsigned io_plugged; 1175 1176 /* do we need to tell the quest if we have a volatile write cache? */ 1177 int enable_write_cache; 1178 1179 /* Accessed with atomic ops. */ 1180 int quiesce_counter; 1181 1182 unsigned int write_gen; /* Current data generation */ 1183 1184 /* Protected by reqs_lock. */ 1185 CoMutex reqs_lock; 1186 QLIST_HEAD(, BdrvTrackedRequest) tracked_requests; 1187 CoQueue flush_queue; /* Serializing flush queue */ 1188 bool active_flush_req; /* Flush request in flight? */ 1189 1190 /* Only read/written by whoever has set active_flush_req to true. */ 1191 unsigned int flushed_gen; /* Flushed write generation */ 1192 1193 /* BdrvChild links to this node may never be frozen */ 1194 bool never_freeze; 1195 1196 /* Lock for block-status cache RCU writers */ 1197 CoMutex bsc_modify_lock; 1198 /* Always non-NULL, but must only be dereferenced under an RCU read guard */ 1199 BdrvBlockStatusCache *block_status_cache; 1200 }; 1201 1202 struct BlockBackendRootState { 1203 int open_flags; 1204 BlockdevDetectZeroesOptions detect_zeroes; 1205 }; 1206 1207 typedef enum BlockMirrorBackingMode { 1208 /* 1209 * Reuse the existing backing chain from the source for the target. 1210 * - sync=full: Set backing BDS to NULL. 1211 * - sync=top: Use source's backing BDS. 1212 * - sync=none: Use source as the backing BDS. 1213 */ 1214 MIRROR_SOURCE_BACKING_CHAIN, 1215 1216 /* Open the target's backing chain completely anew */ 1217 MIRROR_OPEN_BACKING_CHAIN, 1218 1219 /* Do not change the target's backing BDS after job completion */ 1220 MIRROR_LEAVE_BACKING_CHAIN, 1221 } BlockMirrorBackingMode; 1222 1223 1224 /* 1225 * Essential block drivers which must always be statically linked into qemu, and 1226 * which therefore can be accessed without using bdrv_find_format() 1227 */ 1228 extern BlockDriver bdrv_file; 1229 extern BlockDriver bdrv_raw; 1230 extern BlockDriver bdrv_qcow2; 1231 1232 extern unsigned int bdrv_drain_all_count; 1233 extern QemuOptsList bdrv_create_opts_simple; 1234 1235 /* 1236 * Common functions that are neither I/O nor Global State. 1237 * 1238 * See include/block/block-commmon.h for more information about 1239 * the Common API. 1240 */ 1241 1242 static inline BlockDriverState *child_bs(BdrvChild *child) 1243 { 1244 return child ? child->bs : NULL; 1245 } 1246 1247 int bdrv_check_request(int64_t offset, int64_t bytes, Error **errp); 1248 char *create_tmp_file(Error **errp); 1249 void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix, 1250 QDict *options); 1251 1252 1253 int bdrv_check_qiov_request(int64_t offset, int64_t bytes, 1254 QEMUIOVector *qiov, size_t qiov_offset, 1255 Error **errp); 1256 1257 #ifdef _WIN32 1258 int is_windows_drive(const char *filename); 1259 #endif 1260 1261 #endif /* BLOCK_INT_COMMON_H */ 1262