2 * QEMU System Emulator block driver
4 * Copyright (c) 2003 Fabrice Bellard
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:
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
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
24 #ifndef BLOCK_INT_COMMON_H
25 #define BLOCK_INT_COMMON_H
27 #include "block/aio.h"
28 #include "block/block-common.h"
29 #include "block/block-global-state.h"
30 #include "block/snapshot.h"
33 #include "qemu/stats64.h"
35 #define BLOCK_FLAG_LAZY_REFCOUNTS 8
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"
61 #define BLOCK_PROBE_BUF_SIZE 512
63 enum BdrvTrackedRequestType
{
67 BDRV_TRACKED_TRUNCATE
,
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
76 typedef struct BdrvTrackedRequest
{
80 enum BdrvTrackedRequestType type
;
83 int64_t overlap_offset
;
84 int64_t overlap_bytes
;
86 QLIST_ENTRY(BdrvTrackedRequest
) list
;
87 Coroutine
*co
; /* owner, used for deadlock detection */
88 CoQueue wait_queue
; /* coroutines blocked on this request */
90 struct BdrvTrackedRequest
*waiting_for
;
96 * These fields are initialized when this object is created,
97 * and are never changed afterwards.
100 const char *format_name
;
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
109 * Note that filters are not allowed to modify data.
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.)
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.
125 * Never create any more such filters!
127 * TODO: imagine how to deprecate this behavior and make all filters work
128 * similarly using bs->file as filtered child.
130 bool filtered_child_is_backing
;
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
141 * Set to true if the BlockDriver supports zoned children.
143 bool supports_zoned_children
;
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
149 * An example of the last type will be the quorum block driver.
151 bool bdrv_needs_filename
;
154 * Set if a driver can support backing files. This also implies the
155 * following semantics:
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
164 bool supports_backing
;
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.
172 const char *protocol_name
;
174 /* List of options for creating images, terminated by name == NULL */
175 QemuOptsList
*create_opts
;
177 /* List of options for image amend */
178 QemuOptsList
*amend_opts
;
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
187 const char *const *mutable_opts
;
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.
196 const char *const *strong_runtime_opts
;
200 * Global state (GS) API. These functions run under the BQL.
202 * See include/block/block-global-state.h for more information about
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.
212 int GRAPH_RDLOCK_PTR (*bdrv_amend_pre_run
)(
213 BlockDriverState
*bs
, Error
**errp
);
215 * This function is invoked under BQL after .bdrv_co_amend()
216 * to allow cleaning up what was done in .bdrv_amend_pre_run().
218 void GRAPH_RDLOCK_PTR (*bdrv_amend_clean
)(BlockDriverState
*bs
);
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).
225 bool GRAPH_RDLOCK_PTR (*bdrv_recurse_can_replace
)(
226 BlockDriverState
*bs
, BlockDriverState
*to_replace
);
228 int (*bdrv_probe_device
)(const char *filename
);
231 * Any driver implementing this callback is expected to be able to handle
232 * NULL file names in its .bdrv_open() implementation.
234 void (*bdrv_parse_filename
)(const char *filename
, QDict
*options
,
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
);
245 int GRAPH_UNLOCKED_PTR (*bdrv_open
)(
246 BlockDriverState
*bs
, QDict
*options
, int flags
, Error
**errp
);
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
);
253 int coroutine_fn
GRAPH_UNLOCKED_PTR (*bdrv_co_create
)(
254 BlockdevCreateOptions
*opts
, Error
**errp
);
256 int coroutine_fn
GRAPH_UNLOCKED_PTR (*bdrv_co_create_opts
)(
257 BlockDriver
*drv
, const char *filename
, QemuOpts
*opts
, Error
**errp
);
259 int (*bdrv_amend_options
)(BlockDriverState
*bs
,
261 BlockDriverAmendStatusCB
*status_cb
,
266 int (*bdrv_make_empty
)(BlockDriverState
*bs
);
269 * Refreshes the bs->exact_filename field. If that is impossible,
270 * bs->exact_filename has to be left empty.
272 void (*bdrv_refresh_filename
)(BlockDriverState
*bs
);
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:
279 * QINCREF(bs->file->bs->full_open_options);
280 * qdict_put(target, "file", bs->file->bs->full_open_options);
282 * If not specified, the generic implementation will simply put
283 * all children's options under their respective name.
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.
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.
295 void (*bdrv_gather_child_options
)(BlockDriverState
*bs
, QDict
*target
,
296 bool backing_overridden
);
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.
303 char *(*bdrv_dirname
)(BlockDriverState
*bs
, Error
**errp
);
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.
309 * One example usage is to avoid waiting for an nbd target node reconnect
310 * timeout during job-cancel with force=true.
312 void (*bdrv_cancel_in_flight
)(BlockDriverState
*bs
);
314 int GRAPH_RDLOCK_PTR (*bdrv_inactivate
)(BlockDriverState
*bs
);
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
,
324 int (*bdrv_snapshot_list
)(BlockDriverState
*bs
,
325 QEMUSnapshotInfo
**psn_info
);
326 int (*bdrv_snapshot_load_tmp
)(BlockDriverState
*bs
,
327 const char *snapshot_id
,
331 int (*bdrv_change_backing_file
)(BlockDriverState
*bs
,
332 const char *backing_file
, const char *backing_fmt
);
334 /* TODO Better pass a option string/QDict/QemuOpts to add any rule? */
335 int (*bdrv_debug_breakpoint
)(BlockDriverState
*bs
, const char *event
,
337 int (*bdrv_debug_remove_breakpoint
)(BlockDriverState
*bs
,
339 int (*bdrv_debug_resume
)(BlockDriverState
*bs
, const char *tag
);
340 bool (*bdrv_debug_is_suspended
)(BlockDriverState
*bs
, const char *tag
);
342 void GRAPH_RDLOCK_PTR (*bdrv_refresh_limits
)(
343 BlockDriverState
*bs
, Error
**errp
);
346 * Returns 1 if newly created images are guaranteed to contain only
347 * zeros, 0 otherwise.
349 int (*bdrv_has_zero_init
)(BlockDriverState
*bs
);
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.
356 void (*bdrv_detach_aio_context
)(BlockDriverState
*bs
);
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.
363 void (*bdrv_attach_aio_context
)(BlockDriverState
*bs
,
364 AioContext
*new_context
);
367 * bdrv_drain_begin is called if implemented in the beginning of a
368 * drain operation to drain and stop any internal sources of requests in
370 * bdrv_drain_end is called if implemented at the end of the drain.
372 * They should be used by the driver to e.g. manage scheduled I/O
373 * requests, or toggle an internal state. After the end of the drain new
374 * requests will continue normally.
376 * Implementations of both functions must not call aio_poll().
378 void (*bdrv_drain_begin
)(BlockDriverState
*bs
);
379 void (*bdrv_drain_end
)(BlockDriverState
*bs
);
382 * Try to get @bs's logical and physical block size.
383 * On success, store them in @bsz and return zero.
384 * On failure, return negative errno.
386 int (*bdrv_probe_blocksizes
)(BlockDriverState
*bs
, BlockSizes
*bsz
);
388 * Try to get @bs's geometry (cyls, heads, sectors)
389 * On success, store them in @geo and return 0.
390 * On failure return -errno.
391 * Only drivers that want to override guest geometry implement this
392 * callback; see hd_geometry_guess().
394 int (*bdrv_probe_geometry
)(BlockDriverState
*bs
, HDGeometry
*geo
);
396 void GRAPH_WRLOCK_PTR (*bdrv_add_child
)(
397 BlockDriverState
*parent
, BlockDriverState
*child
, Error
**errp
);
399 void GRAPH_WRLOCK_PTR (*bdrv_del_child
)(
400 BlockDriverState
*parent
, BdrvChild
*child
, Error
**errp
);
403 * Informs the block driver that a permission change is intended. The
404 * driver checks whether the change is permissible and may take other
405 * preparations for the change (e.g. get file system locks). This operation
406 * is always followed either by a call to either .bdrv_set_perm or
407 * .bdrv_abort_perm_update.
409 * Checks whether the requested set of cumulative permissions in @perm
410 * can be granted for accessing @bs and whether no other users are using
411 * permissions other than those given in @shared (both arguments take
412 * BLK_PERM_* bitmasks).
414 * If both conditions are met, 0 is returned. Otherwise, -errno is returned
415 * and errp is set to an error describing the conflict.
417 int GRAPH_RDLOCK_PTR (*bdrv_check_perm
)(BlockDriverState
*bs
, uint64_t perm
,
418 uint64_t shared
, Error
**errp
);
421 * Called to inform the driver that the set of cumulative set of used
422 * permissions for @bs has changed to @perm, and the set of shareable
423 * permission to @shared. The driver can use this to propagate changes to
424 * its children (i.e. request permissions only if a parent actually needs
427 * This function is only invoked after bdrv_check_perm(), so block drivers
428 * may rely on preparations made in their .bdrv_check_perm implementation.
430 void GRAPH_RDLOCK_PTR (*bdrv_set_perm
)(
431 BlockDriverState
*bs
, uint64_t perm
, uint64_t shared
);
434 * Called to inform the driver that after a previous bdrv_check_perm()
435 * call, the permission update is not performed and any preparations made
436 * for it (e.g. taken file locks) need to be undone.
438 * This function can be called even for nodes that never saw a
439 * bdrv_check_perm() call. It is a no-op then.
441 void GRAPH_RDLOCK_PTR (*bdrv_abort_perm_update
)(BlockDriverState
*bs
);
444 * Returns in @nperm and @nshared the permissions that the driver for @bs
445 * needs on its child @c, based on the cumulative permissions requested by
446 * the parents in @parent_perm and @parent_shared.
448 * If @c is NULL, return the permissions for attaching a new child for the
449 * given @child_class and @role.
451 * If @reopen_queue is non-NULL, don't return the currently needed
452 * permissions, but those that will be needed after applying the
455 void GRAPH_RDLOCK_PTR (*bdrv_child_perm
)(
456 BlockDriverState
*bs
, BdrvChild
*c
, BdrvChildRole role
,
457 BlockReopenQueue
*reopen_queue
,
458 uint64_t parent_perm
, uint64_t parent_shared
,
459 uint64_t *nperm
, uint64_t *nshared
);
462 * Register/unregister a buffer for I/O. For example, when the driver is
463 * interested to know the memory areas that will later be used in iovs, so
464 * that it can do IOMMU mapping with VFIO etc., in order to get better
465 * performance. In the case of VFIO drivers, this callback is used to do
466 * DMA mapping for hot buffers.
468 * Returns: true on success, false on failure
470 bool GRAPH_RDLOCK_PTR (*bdrv_register_buf
)(
471 BlockDriverState
*bs
, void *host
, size_t size
, Error
**errp
);
472 void GRAPH_RDLOCK_PTR (*bdrv_unregister_buf
)(
473 BlockDriverState
*bs
, void *host
, size_t size
);
476 * This field is modified only under the BQL, and is part of
479 QLIST_ENTRY(BlockDriver
) list
;
482 * I/O API functions. These functions are thread-safe.
484 * See include/block/block-io.h for more information about
488 int (*bdrv_probe
)(const uint8_t *buf
, int buf_size
, const char *filename
);
490 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_amend
)(
491 BlockDriverState
*bs
, BlockdevAmendOptions
*opts
, bool force
,
495 BlockAIOCB
* GRAPH_RDLOCK_PTR (*bdrv_aio_preadv
)(BlockDriverState
*bs
,
496 int64_t offset
, int64_t bytes
, QEMUIOVector
*qiov
,
497 BdrvRequestFlags flags
, BlockCompletionFunc
*cb
, void *opaque
);
499 BlockAIOCB
* GRAPH_RDLOCK_PTR (*bdrv_aio_pwritev
)(BlockDriverState
*bs
,
500 int64_t offset
, int64_t bytes
, QEMUIOVector
*qiov
,
501 BdrvRequestFlags flags
, BlockCompletionFunc
*cb
, void *opaque
);
503 BlockAIOCB
* GRAPH_RDLOCK_PTR (*bdrv_aio_flush
)(
504 BlockDriverState
*bs
, BlockCompletionFunc
*cb
, void *opaque
);
506 BlockAIOCB
* GRAPH_RDLOCK_PTR (*bdrv_aio_pdiscard
)(
507 BlockDriverState
*bs
, int64_t offset
, int bytes
,
508 BlockCompletionFunc
*cb
, void *opaque
);
510 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_readv
)(BlockDriverState
*bs
,
511 int64_t sector_num
, int nb_sectors
, QEMUIOVector
*qiov
);
514 * @offset: position in bytes to read at
515 * @bytes: number of bytes to read
516 * @qiov: the buffers to fill with read data
517 * @flags: currently unused, always 0
519 * @offset and @bytes will be a multiple of 'request_alignment',
520 * but the length of individual @qiov elements does not have to
523 * @bytes will always equal the total size of @qiov, and will be
524 * no larger than 'max_transfer'.
526 * The buffer in @qiov may point directly to guest memory.
528 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_preadv
)(BlockDriverState
*bs
,
529 int64_t offset
, int64_t bytes
, QEMUIOVector
*qiov
,
530 BdrvRequestFlags flags
);
532 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_preadv_part
)(
533 BlockDriverState
*bs
, int64_t offset
, int64_t bytes
,
534 QEMUIOVector
*qiov
, size_t qiov_offset
,
535 BdrvRequestFlags flags
);
537 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_writev
)(BlockDriverState
*bs
,
538 int64_t sector_num
, int nb_sectors
, QEMUIOVector
*qiov
,
541 * @offset: position in bytes to write at
542 * @bytes: number of bytes to write
543 * @qiov: the buffers containing data to write
544 * @flags: zero or more bits allowed by 'supported_write_flags'
546 * @offset and @bytes will be a multiple of 'request_alignment',
547 * but the length of individual @qiov elements does not have to
550 * @bytes will always equal the total size of @qiov, and will be
551 * no larger than 'max_transfer'.
553 * The buffer in @qiov may point directly to guest memory.
555 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_pwritev
)(
556 BlockDriverState
*bs
, int64_t offset
, int64_t bytes
, QEMUIOVector
*qiov
,
557 BdrvRequestFlags flags
);
558 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_pwritev_part
)(
559 BlockDriverState
*bs
, int64_t offset
, int64_t bytes
, QEMUIOVector
*qiov
,
560 size_t qiov_offset
, BdrvRequestFlags flags
);
563 * Efficiently zero a region of the disk image. Typically an image format
564 * would use a compact metadata representation to implement this. This
565 * function pointer may be NULL or return -ENOSUP and .bdrv_co_writev()
566 * will be called instead.
568 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_pwrite_zeroes
)(
569 BlockDriverState
*bs
, int64_t offset
, int64_t bytes
,
570 BdrvRequestFlags flags
);
572 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_pdiscard
)(
573 BlockDriverState
*bs
, int64_t offset
, int64_t bytes
);
576 * Map [offset, offset + nbytes) range onto a child of @bs to copy from,
577 * and invoke bdrv_co_copy_range_from(child, ...), or invoke
578 * bdrv_co_copy_range_to() if @bs is the leaf child to copy data from.
580 * See the comment of bdrv_co_copy_range for the parameter and return value
583 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_copy_range_from
)(
584 BlockDriverState
*bs
, BdrvChild
*src
, int64_t offset
,
585 BdrvChild
*dst
, int64_t dst_offset
, int64_t bytes
,
586 BdrvRequestFlags read_flags
, BdrvRequestFlags write_flags
);
589 * Map [offset, offset + nbytes) range onto a child of bs to copy data to,
590 * and invoke bdrv_co_copy_range_to(child, src, ...), or perform the copy
591 * operation if @bs is the leaf and @src has the same BlockDriver. Return
592 * -ENOTSUP if @bs is the leaf but @src has a different BlockDriver.
594 * See the comment of bdrv_co_copy_range for the parameter and return value
597 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_copy_range_to
)(
598 BlockDriverState
*bs
, BdrvChild
*src
, int64_t src_offset
,
599 BdrvChild
*dst
, int64_t dst_offset
, int64_t bytes
,
600 BdrvRequestFlags read_flags
, BdrvRequestFlags write_flags
);
603 * Building block for bdrv_block_status[_above] and
604 * bdrv_is_allocated[_above]. The driver should answer only
605 * according to the current layer, and should only need to set
606 * BDRV_BLOCK_DATA, BDRV_BLOCK_ZERO, BDRV_BLOCK_OFFSET_VALID,
607 * and/or BDRV_BLOCK_RAW; if the current layer defers to a backing
608 * layer, the result should be 0 (and not BDRV_BLOCK_ZERO). See
609 * block.h for the overall meaning of the bits. As a hint, the
610 * flag want_zero is true if the caller cares more about precise
611 * mappings (favor accurate _OFFSET_VALID/_ZERO) or false for
612 * overall allocation (favor larger *pnum, perhaps by reporting
613 * _DATA instead of _ZERO). The block layer guarantees input
614 * clamped to bdrv_getlength() and aligned to request_alignment,
615 * as well as non-NULL pnum, map, and file; in turn, the driver
616 * must return an error or set pnum to an aligned non-zero value.
618 * Note that @bytes is just a hint on how big of a region the
619 * caller wants to inspect. It is not a limit on *pnum.
620 * Implementations are free to return larger values of *pnum if
621 * doing so does not incur a performance penalty.
623 * block/io.c's bdrv_co_block_status() will utilize an unclamped
624 * *pnum value for the block-status cache on protocol nodes, prior
625 * to clamping *pnum for return to its caller.
627 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_block_status
)(
628 BlockDriverState
*bs
,
629 bool want_zero
, int64_t offset
, int64_t bytes
, int64_t *pnum
,
630 int64_t *map
, BlockDriverState
**file
);
633 * Snapshot-access API.
635 * Block-driver may provide snapshot-access API: special functions to access
636 * some internal "snapshot". The functions are similar with normal
637 * read/block_status/discard handler, but don't have any specific handling
638 * in generic block-layer: no serializing, no alignment, no tracked
639 * requests. So, block-driver that realizes these APIs is fully responsible
640 * for synchronization between snapshot-access API and normal IO requests.
642 * TODO: To be able to support qcow2's internal snapshots, this API will
643 * need to be extended to:
644 * - be able to select a specific snapshot
645 * - receive the snapshot's actual length (which may differ from bs's
648 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_preadv_snapshot
)(
649 BlockDriverState
*bs
, int64_t offset
, int64_t bytes
,
650 QEMUIOVector
*qiov
, size_t qiov_offset
);
652 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_snapshot_block_status
)(
653 BlockDriverState
*bs
, bool want_zero
, int64_t offset
, int64_t bytes
,
654 int64_t *pnum
, int64_t *map
, BlockDriverState
**file
);
656 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_pdiscard_snapshot
)(
657 BlockDriverState
*bs
, int64_t offset
, int64_t bytes
);
660 * Invalidate any cached meta-data.
662 void coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_invalidate_cache
)(
663 BlockDriverState
*bs
, Error
**errp
);
666 * Flushes all data for all layers by calling bdrv_co_flush for underlying
667 * layers, if needed. This function is needed for deterministic
668 * synchronization of the flush finishing callback.
670 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_flush
)(BlockDriverState
*bs
);
672 /* Delete a created file. */
673 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_delete_file
)(
674 BlockDriverState
*bs
, Error
**errp
);
677 * Flushes all data that was already written to the OS all the way down to
678 * the disk (for example file-posix.c calls fsync()).
680 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_flush_to_disk
)(
681 BlockDriverState
*bs
);
684 * Flushes all internal caches to the OS. The data may still sit in a
685 * writeback cache of the host OS, but it will survive a crash of the qemu
688 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_flush_to_os
)(
689 BlockDriverState
*bs
);
692 * Truncate @bs to @offset bytes using the given @prealloc mode
693 * when growing. Modes other than PREALLOC_MODE_OFF should be
694 * rejected when shrinking @bs.
696 * If @exact is true, @bs must be resized to exactly @offset.
697 * Otherwise, it is sufficient for @bs (if it is a host block
698 * device and thus there is no way to resize it) to be at least
699 * @offset bytes in length.
701 * If @exact is true and this function fails but would succeed
702 * with @exact = false, it should return -ENOTSUP.
704 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_truncate
)(
705 BlockDriverState
*bs
, int64_t offset
, bool exact
,
706 PreallocMode prealloc
, BdrvRequestFlags flags
, Error
**errp
);
708 int64_t coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_getlength
)(
709 BlockDriverState
*bs
);
711 int64_t coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_get_allocated_file_size
)(
712 BlockDriverState
*bs
);
714 BlockMeasureInfo
*(*bdrv_measure
)(QemuOpts
*opts
, BlockDriverState
*in_bs
,
717 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_pwritev_compressed
)(
718 BlockDriverState
*bs
, int64_t offset
, int64_t bytes
,
721 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_pwritev_compressed_part
)(
722 BlockDriverState
*bs
, int64_t offset
, int64_t bytes
,
723 QEMUIOVector
*qiov
, size_t qiov_offset
);
725 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_get_info
)(
726 BlockDriverState
*bs
, BlockDriverInfo
*bdi
);
728 ImageInfoSpecific
*(*bdrv_get_specific_info
)(BlockDriverState
*bs
,
730 BlockStatsSpecific
*(*bdrv_get_specific_stats
)(BlockDriverState
*bs
);
732 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_save_vmstate
)(
733 BlockDriverState
*bs
, QEMUIOVector
*qiov
, int64_t pos
);
735 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_load_vmstate
)(
736 BlockDriverState
*bs
, QEMUIOVector
*qiov
, int64_t pos
);
738 int coroutine_fn (*bdrv_co_zone_report
)(BlockDriverState
*bs
,
739 int64_t offset
, unsigned int *nr_zones
,
740 BlockZoneDescriptor
*zones
);
741 int coroutine_fn (*bdrv_co_zone_mgmt
)(BlockDriverState
*bs
, BlockZoneOp op
,
742 int64_t offset
, int64_t len
);
743 int coroutine_fn (*bdrv_co_zone_append
)(BlockDriverState
*bs
,
744 int64_t *offset
, QEMUIOVector
*qiov
,
745 BdrvRequestFlags flags
);
747 /* removable device specific */
748 bool coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_is_inserted
)(
749 BlockDriverState
*bs
);
750 void coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_eject
)(
751 BlockDriverState
*bs
, bool eject_flag
);
752 void coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_lock_medium
)(
753 BlockDriverState
*bs
, bool locked
);
755 /* to control generic scsi devices */
756 BlockAIOCB
*coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_aio_ioctl
)(
757 BlockDriverState
*bs
, unsigned long int req
, void *buf
,
758 BlockCompletionFunc
*cb
, void *opaque
);
760 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_ioctl
)(
761 BlockDriverState
*bs
, unsigned long int req
, void *buf
);
764 * Returns 0 for completed check, -errno for internal errors.
765 * The check results are stored in result.
767 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_check
)(
768 BlockDriverState
*bs
, BdrvCheckResult
*result
, BdrvCheckMode fix
);
770 void coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_debug_event
)(
771 BlockDriverState
*bs
, BlkdebugEvent event
);
773 bool (*bdrv_supports_persistent_dirty_bitmap
)(BlockDriverState
*bs
);
775 bool coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_can_store_new_dirty_bitmap
)(
776 BlockDriverState
*bs
, const char *name
, uint32_t granularity
,
779 int coroutine_fn
GRAPH_RDLOCK_PTR (*bdrv_co_remove_persistent_dirty_bitmap
)(
780 BlockDriverState
*bs
, const char *name
, Error
**errp
);
783 static inline bool TSA_NO_TSA
block_driver_can_compress(BlockDriver
*drv
)
785 return drv
->bdrv_co_pwritev_compressed
||
786 drv
->bdrv_co_pwritev_compressed_part
;
789 typedef struct BlockLimits
{
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
796 uint32_t request_alignment
;
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.
803 int64_t max_pdiscard
;
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
811 uint32_t pdiscard_alignment
;
814 * Maximum number of bytes that can zeroized at once. Must be multiple of
815 * pwrite_zeroes_alignment. 0 means no limit.
817 int64_t max_pwrite_zeroes
;
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
826 uint32_t pwrite_zeroes_alignment
;
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
833 uint32_t opt_transfer
;
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
841 uint32_t max_transfer
;
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.
849 uint64_t max_hw_transfer
;
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.
860 /* memory alignment, in bytes so that no bounce buffer is needed */
861 size_t min_mem_alignment
;
863 /* memory alignment, in bytes, for bounce buffer */
864 size_t opt_mem_alignment
;
866 /* maximum number of iovec elements */
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).
875 bool has_variable_length
;
877 /* device zone model */
878 BlockZoneModel zoned
;
880 /* zone size expressed in bytes */
883 /* total number of zones */
886 /* maximum sectors of a zone append write operation */
887 uint32_t max_append_sectors
;
889 /* maximum number of open zones */
890 uint32_t max_open_zones
;
892 /* maximum number of active zones */
893 uint32_t max_active_zones
;
895 uint32_t write_granularity
;
898 typedef struct BdrvOpBlocker BdrvOpBlocker
;
900 typedef struct BdrvAioNotifier
{
901 void (*attached_aio_context
)(AioContext
*new_context
, void *opaque
);
902 void (*detach_aio_context
)(void *opaque
);
907 QLIST_ENTRY(BdrvAioNotifier
) list
;
910 struct BdrvChildClass
{
912 * If true, bdrv_replace_node() doesn't change the node this BdrvChild
918 * If true, the parent is a BlockDriverState and bdrv_next_all_states()
919 * will return it. This information is used for drain_all, where every node
920 * will be drained separately, so the drain only needs to be propagated to
926 * Global state (GS) API. These functions run under the BQL.
928 * See include/block/block-global-state.h for more information about
931 void (*inherit_options
)(BdrvChildRole role
, bool parent_is_format
,
932 int *child_flags
, QDict
*child_options
,
933 int parent_flags
, QDict
*parent_options
);
934 void (*change_media
)(BdrvChild
*child
, bool load
);
937 * Returns a malloced string that describes the parent of the child for a
938 * human reader. This could be a node-name, BlockBackend name, qdev ID or
939 * QOM path of the device owning the BlockBackend, job type and ID etc. The
940 * caller is responsible for freeing the memory.
942 char *(*get_parent_desc
)(BdrvChild
*child
);
945 * Notifies the parent that the child has been activated/inactivated (e.g.
946 * when migration is completing) and it can start/stop requesting
947 * permissions and doing I/O on it.
949 void GRAPH_RDLOCK_PTR (*activate
)(BdrvChild
*child
, Error
**errp
);
950 int GRAPH_RDLOCK_PTR (*inactivate
)(BdrvChild
*child
);
952 void GRAPH_WRLOCK_PTR (*attach
)(BdrvChild
*child
);
953 void GRAPH_WRLOCK_PTR (*detach
)(BdrvChild
*child
);
956 * If this pair of functions is implemented, the parent doesn't issue new
957 * requests after returning from .drained_begin() until .drained_end() is
960 * These functions must not change the graph (and therefore also must not
961 * call aio_poll(), which could change the graph indirectly).
963 * Note that this can be nested. If drained_begin() was called twice, new
964 * I/O is allowed only after drained_end() was called twice, too.
966 void (*drained_begin
)(BdrvChild
*child
);
967 void (*drained_end
)(BdrvChild
*child
);
970 * Returns whether the parent has pending requests for the child. This
971 * callback is polled after .drained_begin() has been called until all
972 * activity on the child has stopped.
974 bool (*drained_poll
)(BdrvChild
*child
);
977 * Notifies the parent that the filename of its child has changed (e.g.
978 * because the direct child was removed from the backing chain), so that it
979 * can update its reference.
981 int (*update_filename
)(BdrvChild
*child
, BlockDriverState
*new_base
,
982 const char *filename
, Error
**errp
);
984 bool (*change_aio_ctx
)(BdrvChild
*child
, AioContext
*ctx
,
985 GHashTable
*visited
, Transaction
*tran
,
989 * I/O API functions. These functions are thread-safe.
991 * See include/block/block-io.h for more information about
995 void (*resize
)(BdrvChild
*child
);
998 * Returns a name that is supposedly more useful for human users than the
999 * node name for identifying the node in question (in particular, a BB
1000 * name), or NULL if the parent can't provide a better name.
1002 const char *(*get_name
)(BdrvChild
*child
);
1004 AioContext
*(*get_parent_aio_context
)(BdrvChild
*child
);
1007 extern const BdrvChildClass child_of_bds
;
1010 BlockDriverState
*bs
;
1012 const BdrvChildClass
*klass
;
1017 * Granted permissions for operating on this BdrvChild (BLK_PERM_* bitmask)
1022 * Permissions that can still be granted to other users of @bs while this
1023 * BdrvChild is still attached to it. (BLK_PERM_* bitmask)
1025 uint64_t shared_perm
;
1028 * This link is frozen: the child can neither be replaced nor
1029 * detached from the parent.
1034 * True if the parent of this child has been drained by this BdrvChild
1035 * (through klass->drained_*).
1037 * It is generally true if bs->quiesce_counter > 0. It may differ while the
1038 * child is entering or leaving a drained section.
1040 bool quiesced_parent
;
1042 QLIST_ENTRY(BdrvChild
) next
;
1043 QLIST_ENTRY(BdrvChild
) next_parent
;
1047 * Allows bdrv_co_block_status() to cache one data region for a
1050 * @valid: Whether the cache is valid (should be accessed with atomic
1051 * functions so this can be reset by RCU readers)
1052 * @data_start: Offset where we know (or strongly assume) is data
1053 * @data_end: Offset where the data region ends (which is not necessarily
1054 * the start of a zeroed region)
1056 typedef struct BdrvBlockStatusCache
{
1057 struct rcu_head rcu
;
1062 } BdrvBlockStatusCache
;
1064 struct BlockDriverState
{
1066 * Protected by big QEMU lock or read-only after opening. No special
1067 * locking needed during I/O...
1069 int open_flags
; /* flags used to open the file, re-used for re-open */
1070 bool encrypted
; /* if true, the media is encrypted */
1071 bool sg
; /* if true, the device is a /dev/sg* */
1072 bool probed
; /* if true, format was probed rather than specified */
1073 bool force_share
; /* if true, always allow all shared permissions */
1074 bool implicit
; /* if true, this filter node was automatically inserted */
1076 BlockDriver
*drv
; /* NULL means no media */
1079 AioContext
*aio_context
; /* event loop used for fd handlers, timers, etc */
1081 * long-running tasks intended to always use the same AioContext as this
1082 * BDS may register themselves in this list to be notified of changes
1083 * regarding this BDS's context
1085 QLIST_HEAD(, BdrvAioNotifier
) aio_notifiers
;
1086 bool walking_aio_notifiers
; /* to make removal during iteration safe */
1088 char filename
[PATH_MAX
];
1090 * If not empty, this image is a diff in relation to backing_file.
1091 * Note that this is the name given in the image header and
1092 * therefore may or may not be equal to .backing->bs->filename.
1093 * If this field contains a relative path, it is to be resolved
1094 * relatively to the overlay's location.
1096 char backing_file
[PATH_MAX
];
1098 * The backing filename indicated by the image header. Contrary
1099 * to backing_file, if we ever open this file, auto_backing_file
1100 * is replaced by the resulting BDS's filename (i.e. after a
1101 * bdrv_refresh_filename() run).
1103 char auto_backing_file
[PATH_MAX
];
1104 char backing_format
[16]; /* if non-zero and backing_file exists */
1106 QDict
*full_open_options
;
1107 char exact_filename
[PATH_MAX
];
1113 * Flags honored during pread
1115 BdrvRequestFlags supported_read_flags
;
1117 * Flags honored during pwrite (so far: BDRV_REQ_FUA,
1118 * BDRV_REQ_WRITE_UNCHANGED).
1119 * If a driver does not support BDRV_REQ_WRITE_UNCHANGED, those
1120 * writes will be issued as normal writes without the flag set.
1121 * This is important to note for drivers that do not explicitly
1122 * request a WRITE permission for their children and instead take
1123 * the same permissions as their parent did (this is commonly what
1124 * block filters do). Such drivers have to be aware that the
1125 * parent may have taken a WRITE_UNCHANGED permission only and is
1126 * issuing such requests. Drivers either must make sure that
1127 * these requests do not result in plain WRITE accesses (usually
1128 * by supporting BDRV_REQ_WRITE_UNCHANGED, and then forwarding
1129 * every incoming write request as-is, including potentially that
1130 * flag), or they have to explicitly take the WRITE permission for
1133 BdrvRequestFlags supported_write_flags
;
1135 * Flags honored during pwrite_zeroes (so far: BDRV_REQ_FUA,
1136 * BDRV_REQ_MAY_UNMAP, BDRV_REQ_WRITE_UNCHANGED)
1138 BdrvRequestFlags supported_zero_flags
;
1140 * Flags honoured during truncate (so far: BDRV_REQ_ZERO_WRITE).
1142 * If BDRV_REQ_ZERO_WRITE is given, the truncate operation must make sure
1143 * that any added space reads as all zeros. If this can't be guaranteed,
1144 * the operation must fail.
1146 BdrvRequestFlags supported_truncate_flags
;
1148 /* the following member gives a name to every node on the bs graph. */
1150 /* element of the list of named nodes building the graph */
1151 QTAILQ_ENTRY(BlockDriverState
) node_list
;
1152 /* element of the list of all BlockDriverStates (all_bdrv_states) */
1153 QTAILQ_ENTRY(BlockDriverState
) bs_list
;
1154 /* element of the list of monitor-owned BDS */
1155 QTAILQ_ENTRY(BlockDriverState
) monitor_list
;
1158 /* operation blockers. Protected by BQL. */
1159 QLIST_HEAD(, BdrvOpBlocker
) op_blockers
[BLOCK_OP_TYPE_MAX
];
1162 * The node that this node inherited default options from (and a reopen on
1163 * which can affect this node by changing these defaults). This is always a
1164 * parent node of this node.
1166 BlockDriverState
*inherits_from
;
1169 * @backing and @file are some of @children or NULL. All these three fields
1170 * (@file, @backing and @children) are modified only in
1171 * bdrv_child_cb_attach() and bdrv_child_cb_detach().
1173 * See also comment in include/block/block.h, to learn how backing and file
1174 * are connected with BdrvChildRole.
1176 QLIST_HEAD(, BdrvChild
) children
;
1180 QLIST_HEAD(, BdrvChild
) parents
;
1183 QDict
*explicit_options
;
1184 BlockdevDetectZeroesOptions detect_zeroes
;
1186 /* The error object in use for blocking operations on backing_hd */
1187 Error
*backing_blocker
;
1189 /* Protected by AioContext lock */
1192 * If we are reading a disk image, give its size in sectors.
1193 * Generally read-only; it is written to by load_snapshot and
1194 * save_snaphost, but the block layer is quiescent during those.
1196 int64_t total_sectors
;
1198 /* threshold limit for writes, in bytes. "High water mark". */
1199 uint64_t write_threshold_offset
;
1202 * Writing to the list requires the BQL _and_ the dirty_bitmap_mutex.
1203 * Reading from the list can be done with either the BQL or the
1204 * dirty_bitmap_mutex. Modifying a bitmap only requires
1205 * dirty_bitmap_mutex.
1207 QemuMutex dirty_bitmap_mutex
;
1208 QLIST_HEAD(, BdrvDirtyBitmap
) dirty_bitmaps
;
1210 /* Offset after the highest byte written to */
1211 Stat64 wr_highest_offset
;
1214 * If true, copy read backing sectors into image. Can be >1 if more
1215 * than one client has requested copy-on-read. Accessed with atomic
1221 * number of in-flight requests; overall and serialising.
1222 * Accessed with atomic ops.
1224 unsigned int in_flight
;
1225 unsigned int serialising_in_flight
;
1227 /* do we need to tell the quest if we have a volatile write cache? */
1228 int enable_write_cache
;
1230 /* Accessed with atomic ops. */
1231 int quiesce_counter
;
1233 unsigned int write_gen
; /* Current data generation */
1235 /* Protected by reqs_lock. */
1236 QemuMutex reqs_lock
;
1237 QLIST_HEAD(, BdrvTrackedRequest
) tracked_requests
;
1238 CoQueue flush_queue
; /* Serializing flush queue */
1239 bool active_flush_req
; /* Flush request in flight? */
1241 /* Only read/written by whoever has set active_flush_req to true. */
1242 unsigned int flushed_gen
; /* Flushed write generation */
1244 /* BdrvChild links to this node may never be frozen */
1247 /* Lock for block-status cache RCU writers */
1248 CoMutex bsc_modify_lock
;
1249 /* Always non-NULL, but must only be dereferenced under an RCU read guard */
1250 BdrvBlockStatusCache
*block_status_cache
;
1252 /* array of write pointers' location of each zone in the zoned device. */
1256 struct BlockBackendRootState
{
1258 BlockdevDetectZeroesOptions detect_zeroes
;
1261 typedef enum BlockMirrorBackingMode
{
1263 * Reuse the existing backing chain from the source for the target.
1264 * - sync=full: Set backing BDS to NULL.
1265 * - sync=top: Use source's backing BDS.
1266 * - sync=none: Use source as the backing BDS.
1268 MIRROR_SOURCE_BACKING_CHAIN
,
1270 /* Open the target's backing chain completely anew */
1271 MIRROR_OPEN_BACKING_CHAIN
,
1273 /* Do not change the target's backing BDS after job completion */
1274 MIRROR_LEAVE_BACKING_CHAIN
,
1275 } BlockMirrorBackingMode
;
1279 * Essential block drivers which must always be statically linked into qemu, and
1280 * which therefore can be accessed without using bdrv_find_format()
1282 extern BlockDriver bdrv_file
;
1283 extern BlockDriver bdrv_raw
;
1284 extern BlockDriver bdrv_qcow2
;
1286 extern unsigned int bdrv_drain_all_count
;
1287 extern QemuOptsList bdrv_create_opts_simple
;
1290 * Common functions that are neither I/O nor Global State.
1292 * See include/block/block-common.h for more information about
1296 static inline BlockDriverState
*child_bs(BdrvChild
*child
)
1298 return child
? child
->bs
: NULL
;
1301 int bdrv_check_request(int64_t offset
, int64_t bytes
, Error
**errp
);
1302 char *create_tmp_file(Error
**errp
);
1303 void bdrv_parse_filename_strip_prefix(const char *filename
, const char *prefix
,
1307 int bdrv_check_qiov_request(int64_t offset
, int64_t bytes
,
1308 QEMUIOVector
*qiov
, size_t qiov_offset
,
1312 int is_windows_drive(const char *filename
);
1315 #endif /* BLOCK_INT_COMMON_H */