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 * Set to true if the BlockDriver supports zoned children. 142 */ 143 bool supports_zoned_children; 144 145 /* 146 * Drivers not implementing bdrv_parse_filename nor bdrv_open should have 147 * this field set to true, except ones that are defined only by their 148 * child's bs. 149 * An example of the last type will be the quorum block driver. 150 */ 151 bool bdrv_needs_filename; 152 153 /* 154 * Set if a driver can support backing files. This also implies the 155 * following semantics: 156 * 157 * - Return status 0 of .bdrv_co_block_status means that corresponding 158 * blocks are not allocated in this layer of backing-chain 159 * - For such (unallocated) blocks, read will: 160 * - fill buffer with zeros if there is no backing file 161 * - read from the backing file otherwise, where the block layer 162 * takes care of reading zeros beyond EOF if backing file is short 163 */ 164 bool supports_backing; 165 166 /* 167 * Drivers setting this field must be able to work with just a plain 168 * filename with '<protocol_name>:' as a prefix, and no other options. 169 * Options may be extracted from the filename by implementing 170 * bdrv_parse_filename. 171 */ 172 const char *protocol_name; 173 174 /* List of options for creating images, terminated by name == NULL */ 175 QemuOptsList *create_opts; 176 177 /* List of options for image amend */ 178 QemuOptsList *amend_opts; 179 180 /* 181 * If this driver supports reopening images this contains a 182 * NULL-terminated list of the runtime options that can be 183 * modified. If an option in this list is unspecified during 184 * reopen then it _must_ be reset to its default value or return 185 * an error. 186 */ 187 const char *const *mutable_opts; 188 189 /* 190 * Pointer to a NULL-terminated array of names of strong options 191 * that can be specified for bdrv_open(). A strong option is one 192 * that changes the data of a BDS. 193 * If this pointer is NULL, the array is considered empty. 194 * "filename" and "driver" are always considered strong. 195 */ 196 const char *const *strong_runtime_opts; 197 198 199 /* 200 * Global state (GS) API. These functions run under the BQL. 201 * 202 * See include/block/block-global-state.h for more information about 203 * the GS API. 204 */ 205 206 /* 207 * This function is invoked under BQL before .bdrv_co_amend() 208 * (which in contrast does not necessarily run under the BQL) 209 * to allow driver-specific initialization code that requires 210 * the BQL, like setting up specific permission flags. 211 */ 212 int GRAPH_RDLOCK_PTR (*bdrv_amend_pre_run)( 213 BlockDriverState *bs, Error **errp); 214 /* 215 * This function is invoked under BQL after .bdrv_co_amend() 216 * to allow cleaning up what was done in .bdrv_amend_pre_run(). 217 */ 218 void GRAPH_RDLOCK_PTR (*bdrv_amend_clean)(BlockDriverState *bs); 219 220 /* 221 * Return true if @to_replace can be replaced by a BDS with the 222 * same data as @bs without it affecting @bs's behavior (that is, 223 * without it being visible to @bs's parents). 224 */ 225 bool GRAPH_RDLOCK_PTR (*bdrv_recurse_can_replace)( 226 BlockDriverState *bs, BlockDriverState *to_replace); 227 228 int (*bdrv_probe_device)(const char *filename); 229 230 /* 231 * Any driver implementing this callback is expected to be able to handle 232 * NULL file names in its .bdrv_open() implementation. 233 */ 234 void (*bdrv_parse_filename)(const char *filename, QDict *options, 235 Error **errp); 236 237 /* For handling image reopen for split or non-split files. */ 238 int (*bdrv_reopen_prepare)(BDRVReopenState *reopen_state, 239 BlockReopenQueue *queue, Error **errp); 240 void (*bdrv_reopen_commit)(BDRVReopenState *reopen_state); 241 void (*bdrv_reopen_commit_post)(BDRVReopenState *reopen_state); 242 void (*bdrv_reopen_abort)(BDRVReopenState *reopen_state); 243 void (*bdrv_join_options)(QDict *options, QDict *old_options); 244 245 int GRAPH_UNLOCKED_PTR (*bdrv_open)( 246 BlockDriverState *bs, QDict *options, int flags, Error **errp); 247 248 /* Protocol drivers should implement this instead of bdrv_open */ 249 int GRAPH_UNLOCKED_PTR (*bdrv_file_open)( 250 BlockDriverState *bs, QDict *options, int flags, Error **errp); 251 void (*bdrv_close)(BlockDriverState *bs); 252 253 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_create)( 254 BlockdevCreateOptions *opts, Error **errp); 255 256 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_create_opts)( 257 BlockDriver *drv, const char *filename, QemuOpts *opts, Error **errp); 258 259 int (*bdrv_amend_options)(BlockDriverState *bs, 260 QemuOpts *opts, 261 BlockDriverAmendStatusCB *status_cb, 262 void *cb_opaque, 263 bool force, 264 Error **errp); 265 266 int (*bdrv_make_empty)(BlockDriverState *bs); 267 268 /* 269 * Refreshes the bs->exact_filename field. If that is impossible, 270 * bs->exact_filename has to be left empty. 271 */ 272 void (*bdrv_refresh_filename)(BlockDriverState *bs); 273 274 /* 275 * Gathers the open options for all children into @target. 276 * A simple format driver (without backing file support) might 277 * implement this function like this: 278 * 279 * QINCREF(bs->file->bs->full_open_options); 280 * qdict_put(target, "file", bs->file->bs->full_open_options); 281 * 282 * If not specified, the generic implementation will simply put 283 * all children's options under their respective name. 284 * 285 * @backing_overridden is true when bs->backing seems not to be 286 * the child that would result from opening bs->backing_file. 287 * Therefore, if it is true, the backing child's options should be 288 * gathered; otherwise, there is no need since the backing child 289 * is the one implied by the image header. 290 * 291 * Note that ideally this function would not be needed. Every 292 * block driver which implements it is probably doing something 293 * shady regarding its runtime option structure. 294 */ 295 void (*bdrv_gather_child_options)(BlockDriverState *bs, QDict *target, 296 bool backing_overridden); 297 298 /* 299 * Returns an allocated string which is the directory name of this BDS: It 300 * will be used to make relative filenames absolute by prepending this 301 * function's return value to them. 302 */ 303 char *(*bdrv_dirname)(BlockDriverState *bs, Error **errp); 304 305 /* 306 * This informs the driver that we are no longer interested in the result 307 * of in-flight requests, so don't waste the time if possible. 308 * 309 * One example usage is to avoid waiting for an nbd target node reconnect 310 * timeout during job-cancel with force=true. 311 */ 312 void (*bdrv_cancel_in_flight)(BlockDriverState *bs); 313 314 int (*bdrv_inactivate)(BlockDriverState *bs); 315 316 int (*bdrv_snapshot_create)(BlockDriverState *bs, 317 QEMUSnapshotInfo *sn_info); 318 int (*bdrv_snapshot_goto)(BlockDriverState *bs, 319 const char *snapshot_id); 320 int (*bdrv_snapshot_delete)(BlockDriverState *bs, 321 const char *snapshot_id, 322 const char *name, 323 Error **errp); 324 int (*bdrv_snapshot_list)(BlockDriverState *bs, 325 QEMUSnapshotInfo **psn_info); 326 int (*bdrv_snapshot_load_tmp)(BlockDriverState *bs, 327 const char *snapshot_id, 328 const char *name, 329 Error **errp); 330 331 int (*bdrv_change_backing_file)(BlockDriverState *bs, 332 const char *backing_file, const char *backing_fmt); 333 334 /* TODO Better pass a option string/QDict/QemuOpts to add any rule? */ 335 int (*bdrv_debug_breakpoint)(BlockDriverState *bs, const char *event, 336 const char *tag); 337 int (*bdrv_debug_remove_breakpoint)(BlockDriverState *bs, 338 const char *tag); 339 int (*bdrv_debug_resume)(BlockDriverState *bs, const char *tag); 340 bool (*bdrv_debug_is_suspended)(BlockDriverState *bs, const char *tag); 341 342 void GRAPH_RDLOCK_PTR (*bdrv_refresh_limits)( 343 BlockDriverState *bs, Error **errp); 344 345 /* 346 * Returns 1 if newly created images are guaranteed to contain only 347 * zeros, 0 otherwise. 348 */ 349 int (*bdrv_has_zero_init)(BlockDriverState *bs); 350 351 /* 352 * Remove fd handlers, timers, and other event loop callbacks so the event 353 * loop is no longer in use. Called with no in-flight requests and in 354 * depth-first traversal order with parents before child nodes. 355 */ 356 void (*bdrv_detach_aio_context)(BlockDriverState *bs); 357 358 /* 359 * Add fd handlers, timers, and other event loop callbacks so I/O requests 360 * can be processed again. Called with no in-flight requests and in 361 * depth-first traversal order with child nodes before parent nodes. 362 */ 363 void (*bdrv_attach_aio_context)(BlockDriverState *bs, 364 AioContext *new_context); 365 366 /** 367 * Try to get @bs's logical and physical block size. 368 * On success, store them in @bsz and return zero. 369 * On failure, return negative errno. 370 */ 371 int (*bdrv_probe_blocksizes)(BlockDriverState *bs, BlockSizes *bsz); 372 /** 373 * Try to get @bs's geometry (cyls, heads, sectors) 374 * On success, store them in @geo and return 0. 375 * On failure return -errno. 376 * Only drivers that want to override guest geometry implement this 377 * callback; see hd_geometry_guess(). 378 */ 379 int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo); 380 381 void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child, 382 Error **errp); 383 void (*bdrv_del_child)(BlockDriverState *parent, BdrvChild *child, 384 Error **errp); 385 386 /** 387 * Informs the block driver that a permission change is intended. The 388 * driver checks whether the change is permissible and may take other 389 * preparations for the change (e.g. get file system locks). This operation 390 * is always followed either by a call to either .bdrv_set_perm or 391 * .bdrv_abort_perm_update. 392 * 393 * Checks whether the requested set of cumulative permissions in @perm 394 * can be granted for accessing @bs and whether no other users are using 395 * permissions other than those given in @shared (both arguments take 396 * BLK_PERM_* bitmasks). 397 * 398 * If both conditions are met, 0 is returned. Otherwise, -errno is returned 399 * and errp is set to an error describing the conflict. 400 */ 401 int (*bdrv_check_perm)(BlockDriverState *bs, uint64_t perm, 402 uint64_t shared, Error **errp); 403 404 /** 405 * Called to inform the driver that the set of cumulative set of used 406 * permissions for @bs has changed to @perm, and the set of sharable 407 * permission to @shared. The driver can use this to propagate changes to 408 * its children (i.e. request permissions only if a parent actually needs 409 * them). 410 * 411 * This function is only invoked after bdrv_check_perm(), so block drivers 412 * may rely on preparations made in their .bdrv_check_perm implementation. 413 */ 414 void (*bdrv_set_perm)(BlockDriverState *bs, uint64_t perm, uint64_t shared); 415 416 /* 417 * Called to inform the driver that after a previous bdrv_check_perm() 418 * call, the permission update is not performed and any preparations made 419 * for it (e.g. taken file locks) need to be undone. 420 * 421 * This function can be called even for nodes that never saw a 422 * bdrv_check_perm() call. It is a no-op then. 423 */ 424 void (*bdrv_abort_perm_update)(BlockDriverState *bs); 425 426 /** 427 * Returns in @nperm and @nshared the permissions that the driver for @bs 428 * needs on its child @c, based on the cumulative permissions requested by 429 * the parents in @parent_perm and @parent_shared. 430 * 431 * If @c is NULL, return the permissions for attaching a new child for the 432 * given @child_class and @role. 433 * 434 * If @reopen_queue is non-NULL, don't return the currently needed 435 * permissions, but those that will be needed after applying the 436 * @reopen_queue. 437 */ 438 void (*bdrv_child_perm)(BlockDriverState *bs, BdrvChild *c, 439 BdrvChildRole role, 440 BlockReopenQueue *reopen_queue, 441 uint64_t parent_perm, uint64_t parent_shared, 442 uint64_t *nperm, uint64_t *nshared); 443 444 /** 445 * Register/unregister a buffer for I/O. For example, when the driver is 446 * interested to know the memory areas that will later be used in iovs, so 447 * that it can do IOMMU mapping with VFIO etc., in order to get better 448 * performance. In the case of VFIO drivers, this callback is used to do 449 * DMA mapping for hot buffers. 450 * 451 * Returns: true on success, false on failure 452 */ 453 bool GRAPH_RDLOCK_PTR (*bdrv_register_buf)( 454 BlockDriverState *bs, void *host, size_t size, Error **errp); 455 void GRAPH_RDLOCK_PTR (*bdrv_unregister_buf)( 456 BlockDriverState *bs, void *host, size_t size); 457 458 /* 459 * This field is modified only under the BQL, and is part of 460 * the global state. 461 */ 462 QLIST_ENTRY(BlockDriver) list; 463 464 /* 465 * I/O API functions. These functions are thread-safe. 466 * 467 * See include/block/block-io.h for more information about 468 * the I/O API. 469 */ 470 471 int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename); 472 473 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_amend)( 474 BlockDriverState *bs, BlockdevAmendOptions *opts, bool force, 475 Error **errp); 476 477 /* aio */ 478 BlockAIOCB * GRAPH_RDLOCK_PTR (*bdrv_aio_preadv)(BlockDriverState *bs, 479 int64_t offset, int64_t bytes, QEMUIOVector *qiov, 480 BdrvRequestFlags flags, BlockCompletionFunc *cb, void *opaque); 481 482 BlockAIOCB * GRAPH_RDLOCK_PTR (*bdrv_aio_pwritev)(BlockDriverState *bs, 483 int64_t offset, int64_t bytes, QEMUIOVector *qiov, 484 BdrvRequestFlags flags, BlockCompletionFunc *cb, void *opaque); 485 486 BlockAIOCB * GRAPH_RDLOCK_PTR (*bdrv_aio_flush)( 487 BlockDriverState *bs, BlockCompletionFunc *cb, void *opaque); 488 489 BlockAIOCB * GRAPH_RDLOCK_PTR (*bdrv_aio_pdiscard)( 490 BlockDriverState *bs, int64_t offset, int bytes, 491 BlockCompletionFunc *cb, void *opaque); 492 493 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_readv)(BlockDriverState *bs, 494 int64_t sector_num, int nb_sectors, QEMUIOVector *qiov); 495 496 /** 497 * @offset: position in bytes to read at 498 * @bytes: number of bytes to read 499 * @qiov: the buffers to fill with read data 500 * @flags: currently unused, always 0 501 * 502 * @offset and @bytes will be a multiple of 'request_alignment', 503 * but the length of individual @qiov elements does not have to 504 * be a multiple. 505 * 506 * @bytes will always equal the total size of @qiov, and will be 507 * no larger than 'max_transfer'. 508 * 509 * The buffer in @qiov may point directly to guest memory. 510 */ 511 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_preadv)(BlockDriverState *bs, 512 int64_t offset, int64_t bytes, QEMUIOVector *qiov, 513 BdrvRequestFlags flags); 514 515 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_preadv_part)( 516 BlockDriverState *bs, int64_t offset, int64_t bytes, 517 QEMUIOVector *qiov, size_t qiov_offset, 518 BdrvRequestFlags flags); 519 520 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_writev)(BlockDriverState *bs, 521 int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, 522 int flags); 523 /** 524 * @offset: position in bytes to write at 525 * @bytes: number of bytes to write 526 * @qiov: the buffers containing data to write 527 * @flags: zero or more bits allowed by 'supported_write_flags' 528 * 529 * @offset and @bytes will be a multiple of 'request_alignment', 530 * but the length of individual @qiov elements does not have to 531 * be a multiple. 532 * 533 * @bytes will always equal the total size of @qiov, and will be 534 * no larger than 'max_transfer'. 535 * 536 * The buffer in @qiov may point directly to guest memory. 537 */ 538 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwritev)( 539 BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, 540 BdrvRequestFlags flags); 541 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwritev_part)( 542 BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, 543 size_t qiov_offset, BdrvRequestFlags flags); 544 545 /* 546 * Efficiently zero a region of the disk image. Typically an image format 547 * would use a compact metadata representation to implement this. This 548 * function pointer may be NULL or return -ENOSUP and .bdrv_co_writev() 549 * will be called instead. 550 */ 551 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwrite_zeroes)( 552 BlockDriverState *bs, int64_t offset, int64_t bytes, 553 BdrvRequestFlags flags); 554 555 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pdiscard)( 556 BlockDriverState *bs, int64_t offset, int64_t bytes); 557 558 /* 559 * Map [offset, offset + nbytes) range onto a child of @bs to copy from, 560 * and invoke bdrv_co_copy_range_from(child, ...), or invoke 561 * bdrv_co_copy_range_to() if @bs is the leaf child to copy data from. 562 * 563 * See the comment of bdrv_co_copy_range for the parameter and return value 564 * semantics. 565 */ 566 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_copy_range_from)( 567 BlockDriverState *bs, BdrvChild *src, int64_t offset, 568 BdrvChild *dst, int64_t dst_offset, int64_t bytes, 569 BdrvRequestFlags read_flags, BdrvRequestFlags write_flags); 570 571 /* 572 * Map [offset, offset + nbytes) range onto a child of bs to copy data to, 573 * and invoke bdrv_co_copy_range_to(child, src, ...), or perform the copy 574 * operation if @bs is the leaf and @src has the same BlockDriver. Return 575 * -ENOTSUP if @bs is the leaf but @src has a different BlockDriver. 576 * 577 * See the comment of bdrv_co_copy_range for the parameter and return value 578 * semantics. 579 */ 580 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_copy_range_to)( 581 BlockDriverState *bs, BdrvChild *src, int64_t src_offset, 582 BdrvChild *dst, int64_t dst_offset, int64_t bytes, 583 BdrvRequestFlags read_flags, BdrvRequestFlags write_flags); 584 585 /* 586 * Building block for bdrv_block_status[_above] and 587 * bdrv_is_allocated[_above]. The driver should answer only 588 * according to the current layer, and should only need to set 589 * BDRV_BLOCK_DATA, BDRV_BLOCK_ZERO, BDRV_BLOCK_OFFSET_VALID, 590 * and/or BDRV_BLOCK_RAW; if the current layer defers to a backing 591 * layer, the result should be 0 (and not BDRV_BLOCK_ZERO). See 592 * block.h for the overall meaning of the bits. As a hint, the 593 * flag want_zero is true if the caller cares more about precise 594 * mappings (favor accurate _OFFSET_VALID/_ZERO) or false for 595 * overall allocation (favor larger *pnum, perhaps by reporting 596 * _DATA instead of _ZERO). The block layer guarantees input 597 * clamped to bdrv_getlength() and aligned to request_alignment, 598 * as well as non-NULL pnum, map, and file; in turn, the driver 599 * must return an error or set pnum to an aligned non-zero value. 600 * 601 * Note that @bytes is just a hint on how big of a region the 602 * caller wants to inspect. It is not a limit on *pnum. 603 * Implementations are free to return larger values of *pnum if 604 * doing so does not incur a performance penalty. 605 * 606 * block/io.c's bdrv_co_block_status() will utilize an unclamped 607 * *pnum value for the block-status cache on protocol nodes, prior 608 * to clamping *pnum for return to its caller. 609 */ 610 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_block_status)( 611 BlockDriverState *bs, 612 bool want_zero, int64_t offset, int64_t bytes, int64_t *pnum, 613 int64_t *map, BlockDriverState **file); 614 615 /* 616 * Snapshot-access API. 617 * 618 * Block-driver may provide snapshot-access API: special functions to access 619 * some internal "snapshot". The functions are similar with normal 620 * read/block_status/discard handler, but don't have any specific handling 621 * in generic block-layer: no serializing, no alignment, no tracked 622 * requests. So, block-driver that realizes these APIs is fully responsible 623 * for synchronization between snapshot-access API and normal IO requests. 624 * 625 * TODO: To be able to support qcow2's internal snapshots, this API will 626 * need to be extended to: 627 * - be able to select a specific snapshot 628 * - receive the snapshot's actual length (which may differ from bs's 629 * length) 630 */ 631 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_preadv_snapshot)( 632 BlockDriverState *bs, int64_t offset, int64_t bytes, 633 QEMUIOVector *qiov, size_t qiov_offset); 634 635 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_snapshot_block_status)( 636 BlockDriverState *bs, bool want_zero, int64_t offset, int64_t bytes, 637 int64_t *pnum, int64_t *map, BlockDriverState **file); 638 639 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pdiscard_snapshot)( 640 BlockDriverState *bs, int64_t offset, int64_t bytes); 641 642 /* 643 * Invalidate any cached meta-data. 644 */ 645 void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_invalidate_cache)( 646 BlockDriverState *bs, Error **errp); 647 648 /* 649 * Flushes all data for all layers by calling bdrv_co_flush for underlying 650 * layers, if needed. This function is needed for deterministic 651 * synchronization of the flush finishing callback. 652 */ 653 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_flush)(BlockDriverState *bs); 654 655 /* Delete a created file. */ 656 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_delete_file)( 657 BlockDriverState *bs, Error **errp); 658 659 /* 660 * Flushes all data that was already written to the OS all the way down to 661 * the disk (for example file-posix.c calls fsync()). 662 */ 663 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_flush_to_disk)( 664 BlockDriverState *bs); 665 666 /* 667 * Flushes all internal caches to the OS. The data may still sit in a 668 * writeback cache of the host OS, but it will survive a crash of the qemu 669 * process. 670 */ 671 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_flush_to_os)( 672 BlockDriverState *bs); 673 674 /* 675 * Truncate @bs to @offset bytes using the given @prealloc mode 676 * when growing. Modes other than PREALLOC_MODE_OFF should be 677 * rejected when shrinking @bs. 678 * 679 * If @exact is true, @bs must be resized to exactly @offset. 680 * Otherwise, it is sufficient for @bs (if it is a host block 681 * device and thus there is no way to resize it) to be at least 682 * @offset bytes in length. 683 * 684 * If @exact is true and this function fails but would succeed 685 * with @exact = false, it should return -ENOTSUP. 686 */ 687 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_truncate)( 688 BlockDriverState *bs, int64_t offset, bool exact, 689 PreallocMode prealloc, BdrvRequestFlags flags, Error **errp); 690 691 int64_t coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_getlength)( 692 BlockDriverState *bs); 693 694 int64_t coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_get_allocated_file_size)( 695 BlockDriverState *bs); 696 697 BlockMeasureInfo *(*bdrv_measure)(QemuOpts *opts, BlockDriverState *in_bs, 698 Error **errp); 699 700 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwritev_compressed)( 701 BlockDriverState *bs, int64_t offset, int64_t bytes, 702 QEMUIOVector *qiov); 703 704 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwritev_compressed_part)( 705 BlockDriverState *bs, int64_t offset, int64_t bytes, 706 QEMUIOVector *qiov, size_t qiov_offset); 707 708 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_get_info)( 709 BlockDriverState *bs, BlockDriverInfo *bdi); 710 711 ImageInfoSpecific *(*bdrv_get_specific_info)(BlockDriverState *bs, 712 Error **errp); 713 BlockStatsSpecific *(*bdrv_get_specific_stats)(BlockDriverState *bs); 714 715 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_save_vmstate)( 716 BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos); 717 718 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_load_vmstate)( 719 BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos); 720 721 int coroutine_fn (*bdrv_co_zone_report)(BlockDriverState *bs, 722 int64_t offset, unsigned int *nr_zones, 723 BlockZoneDescriptor *zones); 724 int coroutine_fn (*bdrv_co_zone_mgmt)(BlockDriverState *bs, BlockZoneOp op, 725 int64_t offset, int64_t len); 726 727 /* removable device specific */ 728 bool coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_is_inserted)( 729 BlockDriverState *bs); 730 void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_eject)( 731 BlockDriverState *bs, bool eject_flag); 732 void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_lock_medium)( 733 BlockDriverState *bs, bool locked); 734 735 /* to control generic scsi devices */ 736 BlockAIOCB *coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_aio_ioctl)( 737 BlockDriverState *bs, unsigned long int req, void *buf, 738 BlockCompletionFunc *cb, void *opaque); 739 740 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_ioctl)( 741 BlockDriverState *bs, unsigned long int req, void *buf); 742 743 /* 744 * Returns 0 for completed check, -errno for internal errors. 745 * The check results are stored in result. 746 */ 747 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_check)( 748 BlockDriverState *bs, BdrvCheckResult *result, BdrvCheckMode fix); 749 750 void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_debug_event)( 751 BlockDriverState *bs, BlkdebugEvent event); 752 753 /* io queue for linux-aio */ 754 void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_io_plug)(BlockDriverState *bs); 755 void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_io_unplug)( 756 BlockDriverState *bs); 757 758 /** 759 * bdrv_drain_begin is called if implemented in the beginning of a 760 * drain operation to drain and stop any internal sources of requests in 761 * the driver. 762 * bdrv_drain_end is called if implemented at the end of the drain. 763 * 764 * They should be used by the driver to e.g. manage scheduled I/O 765 * requests, or toggle an internal state. After the end of the drain new 766 * requests will continue normally. 767 * 768 * Implementations of both functions must not call aio_poll(). 769 */ 770 void (*bdrv_drain_begin)(BlockDriverState *bs); 771 void (*bdrv_drain_end)(BlockDriverState *bs); 772 773 bool (*bdrv_supports_persistent_dirty_bitmap)(BlockDriverState *bs); 774 775 bool coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_can_store_new_dirty_bitmap)( 776 BlockDriverState *bs, const char *name, uint32_t granularity, 777 Error **errp); 778 779 int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_remove_persistent_dirty_bitmap)( 780 BlockDriverState *bs, const char *name, Error **errp); 781 }; 782 783 static inline bool TSA_NO_TSA block_driver_can_compress(BlockDriver *drv) 784 { 785 return drv->bdrv_co_pwritev_compressed || 786 drv->bdrv_co_pwritev_compressed_part; 787 } 788 789 typedef struct BlockLimits { 790 /* 791 * Alignment requirement, in bytes, for offset/length of I/O 792 * requests. Must be a power of 2 less than INT_MAX; defaults to 793 * 1 for drivers with modern byte interfaces, and to 512 794 * otherwise. 795 */ 796 uint32_t request_alignment; 797 798 /* 799 * Maximum number of bytes that can be discarded at once. Must be multiple 800 * of pdiscard_alignment, but need not be power of 2. May be 0 if no 801 * inherent 64-bit limit. 802 */ 803 int64_t max_pdiscard; 804 805 /* 806 * Optimal alignment for discard requests in bytes. A power of 2 807 * is best but not mandatory. Must be a multiple of 808 * bl.request_alignment, and must be less than max_pdiscard if 809 * that is set. May be 0 if bl.request_alignment is good enough 810 */ 811 uint32_t pdiscard_alignment; 812 813 /* 814 * Maximum number of bytes that can zeroized at once. Must be multiple of 815 * pwrite_zeroes_alignment. 0 means no limit. 816 */ 817 int64_t max_pwrite_zeroes; 818 819 /* 820 * Optimal alignment for write zeroes requests in bytes. A power 821 * of 2 is best but not mandatory. Must be a multiple of 822 * bl.request_alignment, and must be less than max_pwrite_zeroes 823 * if that is set. May be 0 if bl.request_alignment is good 824 * enough 825 */ 826 uint32_t pwrite_zeroes_alignment; 827 828 /* 829 * Optimal transfer length in bytes. A power of 2 is best but not 830 * mandatory. Must be a multiple of bl.request_alignment, or 0 if 831 * no preferred size 832 */ 833 uint32_t opt_transfer; 834 835 /* 836 * Maximal transfer length in bytes. Need not be power of 2, but 837 * must be multiple of opt_transfer and bl.request_alignment, or 0 838 * for no 32-bit limit. For now, anything larger than INT_MAX is 839 * clamped down. 840 */ 841 uint32_t max_transfer; 842 843 /* 844 * Maximal hardware transfer length in bytes. Applies whenever 845 * transfers to the device bypass the kernel I/O scheduler, for 846 * example with SG_IO. If larger than max_transfer or if zero, 847 * blk_get_max_hw_transfer will fall back to max_transfer. 848 */ 849 uint64_t max_hw_transfer; 850 851 /* 852 * Maximal number of scatter/gather elements allowed by the hardware. 853 * Applies whenever transfers to the device bypass the kernel I/O 854 * scheduler, for example with SG_IO. If larger than max_iov 855 * or if zero, blk_get_max_hw_iov will fall back to max_iov. 856 */ 857 int max_hw_iov; 858 859 860 /* memory alignment, in bytes so that no bounce buffer is needed */ 861 size_t min_mem_alignment; 862 863 /* memory alignment, in bytes, for bounce buffer */ 864 size_t opt_mem_alignment; 865 866 /* maximum number of iovec elements */ 867 int max_iov; 868 869 /* 870 * true if the length of the underlying file can change, and QEMU 871 * is expected to adjust automatically. Mostly for CD-ROM drives, 872 * whose length is zero when the tray is empty (they don't need 873 * an explicit monitor command to load the disk inside the guest). 874 */ 875 bool has_variable_length; 876 877 /* device zone model */ 878 BlockZoneModel zoned; 879 880 /* zone size expressed in bytes */ 881 uint32_t zone_size; 882 883 /* total number of zones */ 884 uint32_t nr_zones; 885 886 /* maximum sectors of a zone append write operation */ 887 uint32_t max_append_sectors; 888 889 /* maximum number of open zones */ 890 uint32_t max_open_zones; 891 892 /* maximum number of active zones */ 893 uint32_t max_active_zones; 894 } BlockLimits; 895 896 typedef struct BdrvOpBlocker BdrvOpBlocker; 897 898 typedef struct BdrvAioNotifier { 899 void (*attached_aio_context)(AioContext *new_context, void *opaque); 900 void (*detach_aio_context)(void *opaque); 901 902 void *opaque; 903 bool deleted; 904 905 QLIST_ENTRY(BdrvAioNotifier) list; 906 } BdrvAioNotifier; 907 908 struct BdrvChildClass { 909 /* 910 * If true, bdrv_replace_node() doesn't change the node this BdrvChild 911 * points to. 912 */ 913 bool stay_at_node; 914 915 /* 916 * If true, the parent is a BlockDriverState and bdrv_next_all_states() 917 * will return it. This information is used for drain_all, where every node 918 * will be drained separately, so the drain only needs to be propagated to 919 * non-BDS parents. 920 */ 921 bool parent_is_bds; 922 923 /* 924 * Global state (GS) API. These functions run under the BQL. 925 * 926 * See include/block/block-global-state.h for more information about 927 * the GS API. 928 */ 929 void (*inherit_options)(BdrvChildRole role, bool parent_is_format, 930 int *child_flags, QDict *child_options, 931 int parent_flags, QDict *parent_options); 932 void (*change_media)(BdrvChild *child, bool load); 933 934 /* 935 * Returns a malloced string that describes the parent of the child for a 936 * human reader. This could be a node-name, BlockBackend name, qdev ID or 937 * QOM path of the device owning the BlockBackend, job type and ID etc. The 938 * caller is responsible for freeing the memory. 939 */ 940 char *(*get_parent_desc)(BdrvChild *child); 941 942 /* 943 * Notifies the parent that the child has been activated/inactivated (e.g. 944 * when migration is completing) and it can start/stop requesting 945 * permissions and doing I/O on it. 946 */ 947 void (*activate)(BdrvChild *child, Error **errp); 948 int (*inactivate)(BdrvChild *child); 949 950 void GRAPH_WRLOCK_PTR (*attach)(BdrvChild *child); 951 void GRAPH_WRLOCK_PTR (*detach)(BdrvChild *child); 952 953 /* 954 * Notifies the parent that the filename of its child has changed (e.g. 955 * because the direct child was removed from the backing chain), so that it 956 * can update its reference. 957 */ 958 int (*update_filename)(BdrvChild *child, BlockDriverState *new_base, 959 const char *filename, Error **errp); 960 961 bool (*change_aio_ctx)(BdrvChild *child, AioContext *ctx, 962 GHashTable *visited, Transaction *tran, 963 Error **errp); 964 965 /* 966 * I/O API functions. These functions are thread-safe. 967 * 968 * See include/block/block-io.h for more information about 969 * the I/O API. 970 */ 971 972 void (*resize)(BdrvChild *child); 973 974 /* 975 * Returns a name that is supposedly more useful for human users than the 976 * node name for identifying the node in question (in particular, a BB 977 * name), or NULL if the parent can't provide a better name. 978 */ 979 const char *(*get_name)(BdrvChild *child); 980 981 AioContext *(*get_parent_aio_context)(BdrvChild *child); 982 983 /* 984 * If this pair of functions is implemented, the parent doesn't issue new 985 * requests after returning from .drained_begin() until .drained_end() is 986 * called. 987 * 988 * These functions must not change the graph (and therefore also must not 989 * call aio_poll(), which could change the graph indirectly). 990 * 991 * Note that this can be nested. If drained_begin() was called twice, new 992 * I/O is allowed only after drained_end() was called twice, too. 993 */ 994 void (*drained_begin)(BdrvChild *child); 995 void (*drained_end)(BdrvChild *child); 996 997 /* 998 * Returns whether the parent has pending requests for the child. This 999 * callback is polled after .drained_begin() has been called until all 1000 * activity on the child has stopped. 1001 */ 1002 bool (*drained_poll)(BdrvChild *child); 1003 }; 1004 1005 extern const BdrvChildClass child_of_bds; 1006 1007 struct BdrvChild { 1008 BlockDriverState *bs; 1009 char *name; 1010 const BdrvChildClass *klass; 1011 BdrvChildRole role; 1012 void *opaque; 1013 1014 /** 1015 * Granted permissions for operating on this BdrvChild (BLK_PERM_* bitmask) 1016 */ 1017 uint64_t perm; 1018 1019 /** 1020 * Permissions that can still be granted to other users of @bs while this 1021 * BdrvChild is still attached to it. (BLK_PERM_* bitmask) 1022 */ 1023 uint64_t shared_perm; 1024 1025 /* 1026 * This link is frozen: the child can neither be replaced nor 1027 * detached from the parent. 1028 */ 1029 bool frozen; 1030 1031 /* 1032 * True if the parent of this child has been drained by this BdrvChild 1033 * (through klass->drained_*). 1034 * 1035 * It is generally true if bs->quiesce_counter > 0. It may differ while the 1036 * child is entering or leaving a drained section. 1037 */ 1038 bool quiesced_parent; 1039 1040 QLIST_ENTRY(BdrvChild) next; 1041 QLIST_ENTRY(BdrvChild) next_parent; 1042 }; 1043 1044 /* 1045 * Allows bdrv_co_block_status() to cache one data region for a 1046 * protocol node. 1047 * 1048 * @valid: Whether the cache is valid (should be accessed with atomic 1049 * functions so this can be reset by RCU readers) 1050 * @data_start: Offset where we know (or strongly assume) is data 1051 * @data_end: Offset where the data region ends (which is not necessarily 1052 * the start of a zeroed region) 1053 */ 1054 typedef struct BdrvBlockStatusCache { 1055 struct rcu_head rcu; 1056 1057 bool valid; 1058 int64_t data_start; 1059 int64_t data_end; 1060 } BdrvBlockStatusCache; 1061 1062 struct BlockDriverState { 1063 /* 1064 * Protected by big QEMU lock or read-only after opening. No special 1065 * locking needed during I/O... 1066 */ 1067 int open_flags; /* flags used to open the file, re-used for re-open */ 1068 bool encrypted; /* if true, the media is encrypted */ 1069 bool sg; /* if true, the device is a /dev/sg* */ 1070 bool probed; /* if true, format was probed rather than specified */ 1071 bool force_share; /* if true, always allow all shared permissions */ 1072 bool implicit; /* if true, this filter node was automatically inserted */ 1073 1074 BlockDriver *drv; /* NULL means no media */ 1075 void *opaque; 1076 1077 AioContext *aio_context; /* event loop used for fd handlers, timers, etc */ 1078 /* 1079 * long-running tasks intended to always use the same AioContext as this 1080 * BDS may register themselves in this list to be notified of changes 1081 * regarding this BDS's context 1082 */ 1083 QLIST_HEAD(, BdrvAioNotifier) aio_notifiers; 1084 bool walking_aio_notifiers; /* to make removal during iteration safe */ 1085 1086 char filename[PATH_MAX]; 1087 /* 1088 * If not empty, this image is a diff in relation to backing_file. 1089 * Note that this is the name given in the image header and 1090 * therefore may or may not be equal to .backing->bs->filename. 1091 * If this field contains a relative path, it is to be resolved 1092 * relatively to the overlay's location. 1093 */ 1094 char backing_file[PATH_MAX]; 1095 /* 1096 * The backing filename indicated by the image header. Contrary 1097 * to backing_file, if we ever open this file, auto_backing_file 1098 * is replaced by the resulting BDS's filename (i.e. after a 1099 * bdrv_refresh_filename() run). 1100 */ 1101 char auto_backing_file[PATH_MAX]; 1102 char backing_format[16]; /* if non-zero and backing_file exists */ 1103 1104 QDict *full_open_options; 1105 char exact_filename[PATH_MAX]; 1106 1107 /* I/O Limits */ 1108 BlockLimits bl; 1109 1110 /* 1111 * Flags honored during pread 1112 */ 1113 BdrvRequestFlags supported_read_flags; 1114 /* 1115 * Flags honored during pwrite (so far: BDRV_REQ_FUA, 1116 * BDRV_REQ_WRITE_UNCHANGED). 1117 * If a driver does not support BDRV_REQ_WRITE_UNCHANGED, those 1118 * writes will be issued as normal writes without the flag set. 1119 * This is important to note for drivers that do not explicitly 1120 * request a WRITE permission for their children and instead take 1121 * the same permissions as their parent did (this is commonly what 1122 * block filters do). Such drivers have to be aware that the 1123 * parent may have taken a WRITE_UNCHANGED permission only and is 1124 * issuing such requests. Drivers either must make sure that 1125 * these requests do not result in plain WRITE accesses (usually 1126 * by supporting BDRV_REQ_WRITE_UNCHANGED, and then forwarding 1127 * every incoming write request as-is, including potentially that 1128 * flag), or they have to explicitly take the WRITE permission for 1129 * their children. 1130 */ 1131 BdrvRequestFlags supported_write_flags; 1132 /* 1133 * Flags honored during pwrite_zeroes (so far: BDRV_REQ_FUA, 1134 * BDRV_REQ_MAY_UNMAP, BDRV_REQ_WRITE_UNCHANGED) 1135 */ 1136 BdrvRequestFlags supported_zero_flags; 1137 /* 1138 * Flags honoured during truncate (so far: BDRV_REQ_ZERO_WRITE). 1139 * 1140 * If BDRV_REQ_ZERO_WRITE is given, the truncate operation must make sure 1141 * that any added space reads as all zeros. If this can't be guaranteed, 1142 * the operation must fail. 1143 */ 1144 BdrvRequestFlags supported_truncate_flags; 1145 1146 /* the following member gives a name to every node on the bs graph. */ 1147 char node_name[32]; 1148 /* element of the list of named nodes building the graph */ 1149 QTAILQ_ENTRY(BlockDriverState) node_list; 1150 /* element of the list of all BlockDriverStates (all_bdrv_states) */ 1151 QTAILQ_ENTRY(BlockDriverState) bs_list; 1152 /* element of the list of monitor-owned BDS */ 1153 QTAILQ_ENTRY(BlockDriverState) monitor_list; 1154 int refcnt; 1155 1156 /* operation blockers. Protected by BQL. */ 1157 QLIST_HEAD(, BdrvOpBlocker) op_blockers[BLOCK_OP_TYPE_MAX]; 1158 1159 /* 1160 * The node that this node inherited default options from (and a reopen on 1161 * which can affect this node by changing these defaults). This is always a 1162 * parent node of this node. 1163 */ 1164 BlockDriverState *inherits_from; 1165 1166 /* 1167 * @backing and @file are some of @children or NULL. All these three fields 1168 * (@file, @backing and @children) are modified only in 1169 * bdrv_child_cb_attach() and bdrv_child_cb_detach(). 1170 * 1171 * See also comment in include/block/block.h, to learn how backing and file 1172 * are connected with BdrvChildRole. 1173 */ 1174 QLIST_HEAD(, BdrvChild) children; 1175 BdrvChild *backing; 1176 BdrvChild *file; 1177 1178 QLIST_HEAD(, BdrvChild) parents; 1179 1180 QDict *options; 1181 QDict *explicit_options; 1182 BlockdevDetectZeroesOptions detect_zeroes; 1183 1184 /* The error object in use for blocking operations on backing_hd */ 1185 Error *backing_blocker; 1186 1187 /* Protected by AioContext lock */ 1188 1189 /* 1190 * If we are reading a disk image, give its size in sectors. 1191 * Generally read-only; it is written to by load_snapshot and 1192 * save_snaphost, but the block layer is quiescent during those. 1193 */ 1194 int64_t total_sectors; 1195 1196 /* threshold limit for writes, in bytes. "High water mark". */ 1197 uint64_t write_threshold_offset; 1198 1199 /* 1200 * Writing to the list requires the BQL _and_ the dirty_bitmap_mutex. 1201 * Reading from the list can be done with either the BQL or the 1202 * dirty_bitmap_mutex. Modifying a bitmap only requires 1203 * dirty_bitmap_mutex. 1204 */ 1205 QemuMutex dirty_bitmap_mutex; 1206 QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps; 1207 1208 /* Offset after the highest byte written to */ 1209 Stat64 wr_highest_offset; 1210 1211 /* 1212 * If true, copy read backing sectors into image. Can be >1 if more 1213 * than one client has requested copy-on-read. Accessed with atomic 1214 * ops. 1215 */ 1216 int copy_on_read; 1217 1218 /* 1219 * number of in-flight requests; overall and serialising. 1220 * Accessed with atomic ops. 1221 */ 1222 unsigned int in_flight; 1223 unsigned int serialising_in_flight; 1224 1225 /* 1226 * counter for nested bdrv_io_plug. 1227 * Accessed with atomic ops. 1228 */ 1229 unsigned io_plugged; 1230 1231 /* do we need to tell the quest if we have a volatile write cache? */ 1232 int enable_write_cache; 1233 1234 /* Accessed with atomic ops. */ 1235 int quiesce_counter; 1236 1237 unsigned int write_gen; /* Current data generation */ 1238 1239 /* Protected by reqs_lock. */ 1240 CoMutex reqs_lock; 1241 QLIST_HEAD(, BdrvTrackedRequest) tracked_requests; 1242 CoQueue flush_queue; /* Serializing flush queue */ 1243 bool active_flush_req; /* Flush request in flight? */ 1244 1245 /* Only read/written by whoever has set active_flush_req to true. */ 1246 unsigned int flushed_gen; /* Flushed write generation */ 1247 1248 /* BdrvChild links to this node may never be frozen */ 1249 bool never_freeze; 1250 1251 /* Lock for block-status cache RCU writers */ 1252 CoMutex bsc_modify_lock; 1253 /* Always non-NULL, but must only be dereferenced under an RCU read guard */ 1254 BdrvBlockStatusCache *block_status_cache; 1255 }; 1256 1257 struct BlockBackendRootState { 1258 int open_flags; 1259 BlockdevDetectZeroesOptions detect_zeroes; 1260 }; 1261 1262 typedef enum BlockMirrorBackingMode { 1263 /* 1264 * Reuse the existing backing chain from the source for the target. 1265 * - sync=full: Set backing BDS to NULL. 1266 * - sync=top: Use source's backing BDS. 1267 * - sync=none: Use source as the backing BDS. 1268 */ 1269 MIRROR_SOURCE_BACKING_CHAIN, 1270 1271 /* Open the target's backing chain completely anew */ 1272 MIRROR_OPEN_BACKING_CHAIN, 1273 1274 /* Do not change the target's backing BDS after job completion */ 1275 MIRROR_LEAVE_BACKING_CHAIN, 1276 } BlockMirrorBackingMode; 1277 1278 1279 /* 1280 * Essential block drivers which must always be statically linked into qemu, and 1281 * which therefore can be accessed without using bdrv_find_format() 1282 */ 1283 extern BlockDriver bdrv_file; 1284 extern BlockDriver bdrv_raw; 1285 extern BlockDriver bdrv_qcow2; 1286 1287 extern unsigned int bdrv_drain_all_count; 1288 extern QemuOptsList bdrv_create_opts_simple; 1289 1290 /* 1291 * Common functions that are neither I/O nor Global State. 1292 * 1293 * See include/block/block-common.h for more information about 1294 * the Common API. 1295 */ 1296 1297 static inline BlockDriverState *child_bs(BdrvChild *child) 1298 { 1299 return child ? child->bs : NULL; 1300 } 1301 1302 int bdrv_check_request(int64_t offset, int64_t bytes, Error **errp); 1303 char *create_tmp_file(Error **errp); 1304 void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix, 1305 QDict *options); 1306 1307 1308 int bdrv_check_qiov_request(int64_t offset, int64_t bytes, 1309 QEMUIOVector *qiov, size_t qiov_offset, 1310 Error **errp); 1311 1312 #ifdef _WIN32 1313 int is_windows_drive(const char *filename); 1314 #endif 1315 1316 #endif /* BLOCK_INT_COMMON_H */ 1317