qemu/include/block/block_int-common.h
Kevin Wolf e2dd273754 block: Introduce bdrv_co_change_backing_file()
bdrv_change_backing_file() is called both inside and outside coroutine
context. This makes it difficult for it to take the graph lock
internally. It also means that driver implementations need to be able to
run outside of coroutines, too. Switch it to the usual model with a
coroutine based implementation and a co_wrapper instead. The new
function is marked GRAPH_RDLOCK.

As the co_wrapper now runs the function in the AioContext of the node
(as it should always have done), this is not GLOBAL_STATE_CODE() any
more.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231027155333.420094-20-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-11-08 17:56:17 +01:00

1321 lines
49 KiB
C

/*
* QEMU System Emulator block driver
*
* Copyright (c) 2003 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef BLOCK_INT_COMMON_H
#define BLOCK_INT_COMMON_H
#include "block/aio.h"
#include "block/block-common.h"
#include "block/block-global-state.h"
#include "block/snapshot.h"
#include "qemu/iov.h"
#include "qemu/rcu.h"
#include "qemu/stats64.h"
#define BLOCK_FLAG_LAZY_REFCOUNTS 8
#define BLOCK_OPT_SIZE "size"
#define BLOCK_OPT_ENCRYPT "encryption"
#define BLOCK_OPT_ENCRYPT_FORMAT "encrypt.format"
#define BLOCK_OPT_COMPAT6 "compat6"
#define BLOCK_OPT_HWVERSION "hwversion"
#define BLOCK_OPT_BACKING_FILE "backing_file"
#define BLOCK_OPT_BACKING_FMT "backing_fmt"
#define BLOCK_OPT_CLUSTER_SIZE "cluster_size"
#define BLOCK_OPT_TABLE_SIZE "table_size"
#define BLOCK_OPT_PREALLOC "preallocation"
#define BLOCK_OPT_SUBFMT "subformat"
#define BLOCK_OPT_COMPAT_LEVEL "compat"
#define BLOCK_OPT_LAZY_REFCOUNTS "lazy_refcounts"
#define BLOCK_OPT_ADAPTER_TYPE "adapter_type"
#define BLOCK_OPT_REDUNDANCY "redundancy"
#define BLOCK_OPT_NOCOW "nocow"
#define BLOCK_OPT_EXTENT_SIZE_HINT "extent_size_hint"
#define BLOCK_OPT_OBJECT_SIZE "object_size"
#define BLOCK_OPT_REFCOUNT_BITS "refcount_bits"
#define BLOCK_OPT_DATA_FILE "data_file"
#define BLOCK_OPT_DATA_FILE_RAW "data_file_raw"
#define BLOCK_OPT_COMPRESSION_TYPE "compression_type"
#define BLOCK_OPT_EXTL2 "extended_l2"
#define BLOCK_PROBE_BUF_SIZE 512
enum BdrvTrackedRequestType {
BDRV_TRACKED_READ,
BDRV_TRACKED_WRITE,
BDRV_TRACKED_DISCARD,
BDRV_TRACKED_TRUNCATE,
};
/*
* That is not quite good that BdrvTrackedRequest structure is public,
* as block/io.c is very careful about incoming offset/bytes being
* correct. Be sure to assert bdrv_check_request() succeeded after any
* modification of BdrvTrackedRequest object out of block/io.c
*/
typedef struct BdrvTrackedRequest {
BlockDriverState *bs;
int64_t offset;
int64_t bytes;
enum BdrvTrackedRequestType type;
bool serialising;
int64_t overlap_offset;
int64_t overlap_bytes;
QLIST_ENTRY(BdrvTrackedRequest) list;
Coroutine *co; /* owner, used for deadlock detection */
CoQueue wait_queue; /* coroutines blocked on this request */
struct BdrvTrackedRequest *waiting_for;
} BdrvTrackedRequest;
struct BlockDriver {
/*
* These fields are initialized when this object is created,
* and are never changed afterwards.
*/
const char *format_name;
int instance_size;
/*
* Set to true if the BlockDriver is a block filter. Block filters pass
* certain callbacks that refer to data (see block.c) to their bs->file
* or bs->backing (whichever one exists) if the driver doesn't implement
* them. Drivers that do not wish to forward must implement them and return
* -ENOTSUP.
* Note that filters are not allowed to modify data.
*
* Filters generally cannot have more than a single filtered child,
* because the data they present must at all times be the same as
* that on their filtered child. That would be impossible to
* achieve for multiple filtered children.
* (And this filtered child must then be bs->file or bs->backing.)
*/
bool is_filter;
/*
* Only make sense for filter drivers, for others must be false.
* If true, filtered child is bs->backing. Otherwise it's bs->file.
* Two internal filters use bs->backing as filtered child and has this
* field set to true: mirror_top and commit_top. There also two such test
* filters in tests/unit/test-bdrv-graph-mod.c.
*
* Never create any more such filters!
*
* TODO: imagine how to deprecate this behavior and make all filters work
* similarly using bs->file as filtered child.
*/
bool filtered_child_is_backing;
/*
* Set to true if the BlockDriver is a format driver. Format nodes
* generally do not expect their children to be other format nodes
* (except for backing files), and so format probing is disabled
* on those children.
*/
bool is_format;
/*
* Set to true if the BlockDriver supports zoned children.
*/
bool supports_zoned_children;
/*
* Drivers not implementing bdrv_parse_filename nor bdrv_open should have
* this field set to true, except ones that are defined only by their
* child's bs.
* An example of the last type will be the quorum block driver.
*/
bool bdrv_needs_filename;
/*
* Set if a driver can support backing files. This also implies the
* following semantics:
*
* - Return status 0 of .bdrv_co_block_status means that corresponding
* blocks are not allocated in this layer of backing-chain
* - For such (unallocated) blocks, read will:
* - fill buffer with zeros if there is no backing file
* - read from the backing file otherwise, where the block layer
* takes care of reading zeros beyond EOF if backing file is short
*/
bool supports_backing;
/*
* Drivers setting this field must be able to work with just a plain
* filename with '<protocol_name>:' as a prefix, and no other options.
* Options may be extracted from the filename by implementing
* bdrv_parse_filename.
*/
const char *protocol_name;
/* List of options for creating images, terminated by name == NULL */
QemuOptsList *create_opts;
/* List of options for image amend */
QemuOptsList *amend_opts;
/*
* If this driver supports reopening images this contains a
* NULL-terminated list of the runtime options that can be
* modified. If an option in this list is unspecified during
* reopen then it _must_ be reset to its default value or return
* an error.
*/
const char *const *mutable_opts;
/*
* Pointer to a NULL-terminated array of names of strong options
* that can be specified for bdrv_open(). A strong option is one
* that changes the data of a BDS.
* If this pointer is NULL, the array is considered empty.
* "filename" and "driver" are always considered strong.
*/
const char *const *strong_runtime_opts;
/*
* Global state (GS) API. These functions run under the BQL.
*
* See include/block/block-global-state.h for more information about
* the GS API.
*/
/*
* This function is invoked under BQL before .bdrv_co_amend()
* (which in contrast does not necessarily run under the BQL)
* to allow driver-specific initialization code that requires
* the BQL, like setting up specific permission flags.
*/
int GRAPH_RDLOCK_PTR (*bdrv_amend_pre_run)(
BlockDriverState *bs, Error **errp);
/*
* This function is invoked under BQL after .bdrv_co_amend()
* to allow cleaning up what was done in .bdrv_amend_pre_run().
*/
void GRAPH_RDLOCK_PTR (*bdrv_amend_clean)(BlockDriverState *bs);
/*
* Return true if @to_replace can be replaced by a BDS with the
* same data as @bs without it affecting @bs's behavior (that is,
* without it being visible to @bs's parents).
*/
bool GRAPH_RDLOCK_PTR (*bdrv_recurse_can_replace)(
BlockDriverState *bs, BlockDriverState *to_replace);
int (*bdrv_probe_device)(const char *filename);
/*
* Any driver implementing this callback is expected to be able to handle
* NULL file names in its .bdrv_open() implementation.
*/
void (*bdrv_parse_filename)(const char *filename, QDict *options,
Error **errp);
/* For handling image reopen for split or non-split files. */
int GRAPH_UNLOCKED_PTR (*bdrv_reopen_prepare)(
BDRVReopenState *reopen_state, BlockReopenQueue *queue, Error **errp);
void GRAPH_UNLOCKED_PTR (*bdrv_reopen_commit)(
BDRVReopenState *reopen_state);
void GRAPH_UNLOCKED_PTR (*bdrv_reopen_commit_post)(
BDRVReopenState *reopen_state);
void GRAPH_UNLOCKED_PTR (*bdrv_reopen_abort)(
BDRVReopenState *reopen_state);
void (*bdrv_join_options)(QDict *options, QDict *old_options);
int GRAPH_UNLOCKED_PTR (*bdrv_open)(
BlockDriverState *bs, QDict *options, int flags, Error **errp);
/* Protocol drivers should implement this instead of bdrv_open */
int GRAPH_UNLOCKED_PTR (*bdrv_file_open)(
BlockDriverState *bs, QDict *options, int flags, Error **errp);
void (*bdrv_close)(BlockDriverState *bs);
int coroutine_fn GRAPH_UNLOCKED_PTR (*bdrv_co_create)(
BlockdevCreateOptions *opts, Error **errp);
int coroutine_fn GRAPH_UNLOCKED_PTR (*bdrv_co_create_opts)(
BlockDriver *drv, const char *filename, QemuOpts *opts, Error **errp);
int GRAPH_RDLOCK_PTR (*bdrv_amend_options)(
BlockDriverState *bs, QemuOpts *opts,
BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
bool force, Error **errp);
int GRAPH_RDLOCK_PTR (*bdrv_make_empty)(BlockDriverState *bs);
/*
* Refreshes the bs->exact_filename field. If that is impossible,
* bs->exact_filename has to be left empty.
*/
void GRAPH_RDLOCK_PTR (*bdrv_refresh_filename)(BlockDriverState *bs);
/*
* Gathers the open options for all children into @target.
* A simple format driver (without backing file support) might
* implement this function like this:
*
* QINCREF(bs->file->bs->full_open_options);
* qdict_put(target, "file", bs->file->bs->full_open_options);
*
* If not specified, the generic implementation will simply put
* all children's options under their respective name.
*
* @backing_overridden is true when bs->backing seems not to be
* the child that would result from opening bs->backing_file.
* Therefore, if it is true, the backing child's options should be
* gathered; otherwise, there is no need since the backing child
* is the one implied by the image header.
*
* Note that ideally this function would not be needed. Every
* block driver which implements it is probably doing something
* shady regarding its runtime option structure.
*/
void GRAPH_RDLOCK_PTR (*bdrv_gather_child_options)(
BlockDriverState *bs, QDict *target, bool backing_overridden);
/*
* Returns an allocated string which is the directory name of this BDS: It
* will be used to make relative filenames absolute by prepending this
* function's return value to them.
*/
char * GRAPH_RDLOCK_PTR (*bdrv_dirname)(BlockDriverState *bs, Error **errp);
/*
* This informs the driver that we are no longer interested in the result
* of in-flight requests, so don't waste the time if possible.
*
* One example usage is to avoid waiting for an nbd target node reconnect
* timeout during job-cancel with force=true.
*/
void (*bdrv_cancel_in_flight)(BlockDriverState *bs);
int GRAPH_RDLOCK_PTR (*bdrv_inactivate)(BlockDriverState *bs);
int GRAPH_RDLOCK_PTR (*bdrv_snapshot_create)(
BlockDriverState *bs, QEMUSnapshotInfo *sn_info);
int GRAPH_UNLOCKED_PTR (*bdrv_snapshot_goto)(
BlockDriverState *bs, const char *snapshot_id);
int GRAPH_RDLOCK_PTR (*bdrv_snapshot_delete)(
BlockDriverState *bs, const char *snapshot_id, const char *name,
Error **errp);
int (*bdrv_snapshot_list)(BlockDriverState *bs,
QEMUSnapshotInfo **psn_info);
int (*bdrv_snapshot_load_tmp)(BlockDriverState *bs,
const char *snapshot_id,
const char *name,
Error **errp);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_change_backing_file)(
BlockDriverState *bs, const char *backing_file,
const char *backing_fmt);
/* TODO Better pass a option string/QDict/QemuOpts to add any rule? */
int (*bdrv_debug_breakpoint)(BlockDriverState *bs, const char *event,
const char *tag);
int (*bdrv_debug_remove_breakpoint)(BlockDriverState *bs,
const char *tag);
int (*bdrv_debug_resume)(BlockDriverState *bs, const char *tag);
bool (*bdrv_debug_is_suspended)(BlockDriverState *bs, const char *tag);
void GRAPH_RDLOCK_PTR (*bdrv_refresh_limits)(
BlockDriverState *bs, Error **errp);
/*
* Returns 1 if newly created images are guaranteed to contain only
* zeros, 0 otherwise.
*/
int GRAPH_RDLOCK_PTR (*bdrv_has_zero_init)(BlockDriverState *bs);
/*
* Remove fd handlers, timers, and other event loop callbacks so the event
* loop is no longer in use. Called with no in-flight requests and in
* depth-first traversal order with parents before child nodes.
*/
void (*bdrv_detach_aio_context)(BlockDriverState *bs);
/*
* Add fd handlers, timers, and other event loop callbacks so I/O requests
* can be processed again. Called with no in-flight requests and in
* depth-first traversal order with child nodes before parent nodes.
*/
void (*bdrv_attach_aio_context)(BlockDriverState *bs,
AioContext *new_context);
/**
* bdrv_drain_begin is called if implemented in the beginning of a
* drain operation to drain and stop any internal sources of requests in
* the driver.
* bdrv_drain_end is called if implemented at the end of the drain.
*
* They should be used by the driver to e.g. manage scheduled I/O
* requests, or toggle an internal state. After the end of the drain new
* requests will continue normally.
*
* Implementations of both functions must not call aio_poll().
*/
void (*bdrv_drain_begin)(BlockDriverState *bs);
void (*bdrv_drain_end)(BlockDriverState *bs);
/**
* Try to get @bs's logical and physical block size.
* On success, store them in @bsz and return zero.
* On failure, return negative errno.
*/
int GRAPH_RDLOCK_PTR (*bdrv_probe_blocksizes)(
BlockDriverState *bs, BlockSizes *bsz);
/**
* Try to get @bs's geometry (cyls, heads, sectors)
* On success, store them in @geo and return 0.
* On failure return -errno.
* Only drivers that want to override guest geometry implement this
* callback; see hd_geometry_guess().
*/
int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo);
void GRAPH_WRLOCK_PTR (*bdrv_add_child)(
BlockDriverState *parent, BlockDriverState *child, Error **errp);
void GRAPH_WRLOCK_PTR (*bdrv_del_child)(
BlockDriverState *parent, BdrvChild *child, Error **errp);
/**
* Informs the block driver that a permission change is intended. The
* driver checks whether the change is permissible and may take other
* preparations for the change (e.g. get file system locks). This operation
* is always followed either by a call to either .bdrv_set_perm or
* .bdrv_abort_perm_update.
*
* Checks whether the requested set of cumulative permissions in @perm
* can be granted for accessing @bs and whether no other users are using
* permissions other than those given in @shared (both arguments take
* BLK_PERM_* bitmasks).
*
* If both conditions are met, 0 is returned. Otherwise, -errno is returned
* and errp is set to an error describing the conflict.
*/
int GRAPH_RDLOCK_PTR (*bdrv_check_perm)(BlockDriverState *bs, uint64_t perm,
uint64_t shared, Error **errp);
/**
* Called to inform the driver that the set of cumulative set of used
* permissions for @bs has changed to @perm, and the set of shareable
* permission to @shared. The driver can use this to propagate changes to
* its children (i.e. request permissions only if a parent actually needs
* them).
*
* This function is only invoked after bdrv_check_perm(), so block drivers
* may rely on preparations made in their .bdrv_check_perm implementation.
*/
void GRAPH_RDLOCK_PTR (*bdrv_set_perm)(
BlockDriverState *bs, uint64_t perm, uint64_t shared);
/*
* Called to inform the driver that after a previous bdrv_check_perm()
* call, the permission update is not performed and any preparations made
* for it (e.g. taken file locks) need to be undone.
*
* This function can be called even for nodes that never saw a
* bdrv_check_perm() call. It is a no-op then.
*/
void GRAPH_RDLOCK_PTR (*bdrv_abort_perm_update)(BlockDriverState *bs);
/**
* Returns in @nperm and @nshared the permissions that the driver for @bs
* needs on its child @c, based on the cumulative permissions requested by
* the parents in @parent_perm and @parent_shared.
*
* If @c is NULL, return the permissions for attaching a new child for the
* given @child_class and @role.
*
* If @reopen_queue is non-NULL, don't return the currently needed
* permissions, but those that will be needed after applying the
* @reopen_queue.
*/
void GRAPH_RDLOCK_PTR (*bdrv_child_perm)(
BlockDriverState *bs, BdrvChild *c, BdrvChildRole role,
BlockReopenQueue *reopen_queue,
uint64_t parent_perm, uint64_t parent_shared,
uint64_t *nperm, uint64_t *nshared);
/**
* Register/unregister a buffer for I/O. For example, when the driver is
* interested to know the memory areas that will later be used in iovs, so
* that it can do IOMMU mapping with VFIO etc., in order to get better
* performance. In the case of VFIO drivers, this callback is used to do
* DMA mapping for hot buffers.
*
* Returns: true on success, false on failure
*/
bool GRAPH_RDLOCK_PTR (*bdrv_register_buf)(
BlockDriverState *bs, void *host, size_t size, Error **errp);
void GRAPH_RDLOCK_PTR (*bdrv_unregister_buf)(
BlockDriverState *bs, void *host, size_t size);
/*
* This field is modified only under the BQL, and is part of
* the global state.
*/
QLIST_ENTRY(BlockDriver) list;
/*
* I/O API functions. These functions are thread-safe.
*
* See include/block/block-io.h for more information about
* the I/O API.
*/
int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_amend)(
BlockDriverState *bs, BlockdevAmendOptions *opts, bool force,
Error **errp);
/* aio */
BlockAIOCB * GRAPH_RDLOCK_PTR (*bdrv_aio_preadv)(BlockDriverState *bs,
int64_t offset, int64_t bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags, BlockCompletionFunc *cb, void *opaque);
BlockAIOCB * GRAPH_RDLOCK_PTR (*bdrv_aio_pwritev)(BlockDriverState *bs,
int64_t offset, int64_t bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags, BlockCompletionFunc *cb, void *opaque);
BlockAIOCB * GRAPH_RDLOCK_PTR (*bdrv_aio_flush)(
BlockDriverState *bs, BlockCompletionFunc *cb, void *opaque);
BlockAIOCB * GRAPH_RDLOCK_PTR (*bdrv_aio_pdiscard)(
BlockDriverState *bs, int64_t offset, int bytes,
BlockCompletionFunc *cb, void *opaque);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_readv)(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
/**
* @offset: position in bytes to read at
* @bytes: number of bytes to read
* @qiov: the buffers to fill with read data
* @flags: currently unused, always 0
*
* @offset and @bytes will be a multiple of 'request_alignment',
* but the length of individual @qiov elements does not have to
* be a multiple.
*
* @bytes will always equal the total size of @qiov, and will be
* no larger than 'max_transfer'.
*
* The buffer in @qiov may point directly to guest memory.
*/
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_preadv)(BlockDriverState *bs,
int64_t offset, int64_t bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_preadv_part)(
BlockDriverState *bs, int64_t offset, int64_t bytes,
QEMUIOVector *qiov, size_t qiov_offset,
BdrvRequestFlags flags);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_writev)(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov,
int flags);
/**
* @offset: position in bytes to write at
* @bytes: number of bytes to write
* @qiov: the buffers containing data to write
* @flags: zero or more bits allowed by 'supported_write_flags'
*
* @offset and @bytes will be a multiple of 'request_alignment',
* but the length of individual @qiov elements does not have to
* be a multiple.
*
* @bytes will always equal the total size of @qiov, and will be
* no larger than 'max_transfer'.
*
* The buffer in @qiov may point directly to guest memory.
*/
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwritev)(
BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov,
BdrvRequestFlags flags);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwritev_part)(
BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov,
size_t qiov_offset, BdrvRequestFlags flags);
/*
* Efficiently zero a region of the disk image. Typically an image format
* would use a compact metadata representation to implement this. This
* function pointer may be NULL or return -ENOSUP and .bdrv_co_writev()
* will be called instead.
*/
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwrite_zeroes)(
BlockDriverState *bs, int64_t offset, int64_t bytes,
BdrvRequestFlags flags);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pdiscard)(
BlockDriverState *bs, int64_t offset, int64_t bytes);
/*
* Map [offset, offset + nbytes) range onto a child of @bs to copy from,
* and invoke bdrv_co_copy_range_from(child, ...), or invoke
* bdrv_co_copy_range_to() if @bs is the leaf child to copy data from.
*
* See the comment of bdrv_co_copy_range for the parameter and return value
* semantics.
*/
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_copy_range_from)(
BlockDriverState *bs, BdrvChild *src, int64_t offset,
BdrvChild *dst, int64_t dst_offset, int64_t bytes,
BdrvRequestFlags read_flags, BdrvRequestFlags write_flags);
/*
* Map [offset, offset + nbytes) range onto a child of bs to copy data to,
* and invoke bdrv_co_copy_range_to(child, src, ...), or perform the copy
* operation if @bs is the leaf and @src has the same BlockDriver. Return
* -ENOTSUP if @bs is the leaf but @src has a different BlockDriver.
*
* See the comment of bdrv_co_copy_range for the parameter and return value
* semantics.
*/
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_copy_range_to)(
BlockDriverState *bs, BdrvChild *src, int64_t src_offset,
BdrvChild *dst, int64_t dst_offset, int64_t bytes,
BdrvRequestFlags read_flags, BdrvRequestFlags write_flags);
/*
* Building block for bdrv_block_status[_above] and
* bdrv_is_allocated[_above]. The driver should answer only
* according to the current layer, and should only need to set
* BDRV_BLOCK_DATA, BDRV_BLOCK_ZERO, BDRV_BLOCK_OFFSET_VALID,
* and/or BDRV_BLOCK_RAW; if the current layer defers to a backing
* layer, the result should be 0 (and not BDRV_BLOCK_ZERO). See
* block.h for the overall meaning of the bits. As a hint, the
* flag want_zero is true if the caller cares more about precise
* mappings (favor accurate _OFFSET_VALID/_ZERO) or false for
* overall allocation (favor larger *pnum, perhaps by reporting
* _DATA instead of _ZERO). The block layer guarantees input
* clamped to bdrv_getlength() and aligned to request_alignment,
* as well as non-NULL pnum, map, and file; in turn, the driver
* must return an error or set pnum to an aligned non-zero value.
*
* Note that @bytes is just a hint on how big of a region the
* caller wants to inspect. It is not a limit on *pnum.
* Implementations are free to return larger values of *pnum if
* doing so does not incur a performance penalty.
*
* block/io.c's bdrv_co_block_status() will utilize an unclamped
* *pnum value for the block-status cache on protocol nodes, prior
* to clamping *pnum for return to its caller.
*/
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_block_status)(
BlockDriverState *bs,
bool want_zero, int64_t offset, int64_t bytes, int64_t *pnum,
int64_t *map, BlockDriverState **file);
/*
* Snapshot-access API.
*
* Block-driver may provide snapshot-access API: special functions to access
* some internal "snapshot". The functions are similar with normal
* read/block_status/discard handler, but don't have any specific handling
* in generic block-layer: no serializing, no alignment, no tracked
* requests. So, block-driver that realizes these APIs is fully responsible
* for synchronization between snapshot-access API and normal IO requests.
*
* TODO: To be able to support qcow2's internal snapshots, this API will
* need to be extended to:
* - be able to select a specific snapshot
* - receive the snapshot's actual length (which may differ from bs's
* length)
*/
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_preadv_snapshot)(
BlockDriverState *bs, int64_t offset, int64_t bytes,
QEMUIOVector *qiov, size_t qiov_offset);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_snapshot_block_status)(
BlockDriverState *bs, bool want_zero, int64_t offset, int64_t bytes,
int64_t *pnum, int64_t *map, BlockDriverState **file);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pdiscard_snapshot)(
BlockDriverState *bs, int64_t offset, int64_t bytes);
/*
* Invalidate any cached meta-data.
*/
void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_invalidate_cache)(
BlockDriverState *bs, Error **errp);
/*
* Flushes all data for all layers by calling bdrv_co_flush for underlying
* layers, if needed. This function is needed for deterministic
* synchronization of the flush finishing callback.
*/
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_flush)(BlockDriverState *bs);
/* Delete a created file. */
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_delete_file)(
BlockDriverState *bs, Error **errp);
/*
* Flushes all data that was already written to the OS all the way down to
* the disk (for example file-posix.c calls fsync()).
*/
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_flush_to_disk)(
BlockDriverState *bs);
/*
* Flushes all internal caches to the OS. The data may still sit in a
* writeback cache of the host OS, but it will survive a crash of the qemu
* process.
*/
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_flush_to_os)(
BlockDriverState *bs);
/*
* Truncate @bs to @offset bytes using the given @prealloc mode
* when growing. Modes other than PREALLOC_MODE_OFF should be
* rejected when shrinking @bs.
*
* If @exact is true, @bs must be resized to exactly @offset.
* Otherwise, it is sufficient for @bs (if it is a host block
* device and thus there is no way to resize it) to be at least
* @offset bytes in length.
*
* If @exact is true and this function fails but would succeed
* with @exact = false, it should return -ENOTSUP.
*/
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_truncate)(
BlockDriverState *bs, int64_t offset, bool exact,
PreallocMode prealloc, BdrvRequestFlags flags, Error **errp);
int64_t coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_getlength)(
BlockDriverState *bs);
int64_t coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_get_allocated_file_size)(
BlockDriverState *bs);
BlockMeasureInfo *(*bdrv_measure)(QemuOpts *opts, BlockDriverState *in_bs,
Error **errp);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwritev_compressed)(
BlockDriverState *bs, int64_t offset, int64_t bytes,
QEMUIOVector *qiov);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_pwritev_compressed_part)(
BlockDriverState *bs, int64_t offset, int64_t bytes,
QEMUIOVector *qiov, size_t qiov_offset);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_get_info)(
BlockDriverState *bs, BlockDriverInfo *bdi);
ImageInfoSpecific * GRAPH_RDLOCK_PTR (*bdrv_get_specific_info)(
BlockDriverState *bs, Error **errp);
BlockStatsSpecific *(*bdrv_get_specific_stats)(BlockDriverState *bs);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_save_vmstate)(
BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_load_vmstate)(
BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos);
int coroutine_fn (*bdrv_co_zone_report)(BlockDriverState *bs,
int64_t offset, unsigned int *nr_zones,
BlockZoneDescriptor *zones);
int coroutine_fn (*bdrv_co_zone_mgmt)(BlockDriverState *bs, BlockZoneOp op,
int64_t offset, int64_t len);
int coroutine_fn (*bdrv_co_zone_append)(BlockDriverState *bs,
int64_t *offset, QEMUIOVector *qiov,
BdrvRequestFlags flags);
/* removable device specific */
bool coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_is_inserted)(
BlockDriverState *bs);
void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_eject)(
BlockDriverState *bs, bool eject_flag);
void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_lock_medium)(
BlockDriverState *bs, bool locked);
/* to control generic scsi devices */
BlockAIOCB *coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_aio_ioctl)(
BlockDriverState *bs, unsigned long int req, void *buf,
BlockCompletionFunc *cb, void *opaque);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_ioctl)(
BlockDriverState *bs, unsigned long int req, void *buf);
/*
* Returns 0 for completed check, -errno for internal errors.
* The check results are stored in result.
*/
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_check)(
BlockDriverState *bs, BdrvCheckResult *result, BdrvCheckMode fix);
void coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_debug_event)(
BlockDriverState *bs, BlkdebugEvent event);
bool (*bdrv_supports_persistent_dirty_bitmap)(BlockDriverState *bs);
bool coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_can_store_new_dirty_bitmap)(
BlockDriverState *bs, const char *name, uint32_t granularity,
Error **errp);
int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_remove_persistent_dirty_bitmap)(
BlockDriverState *bs, const char *name, Error **errp);
};
static inline bool TSA_NO_TSA block_driver_can_compress(BlockDriver *drv)
{
return drv->bdrv_co_pwritev_compressed ||
drv->bdrv_co_pwritev_compressed_part;
}
typedef struct BlockLimits {
/*
* Alignment requirement, in bytes, for offset/length of I/O
* requests. Must be a power of 2 less than INT_MAX; defaults to
* 1 for drivers with modern byte interfaces, and to 512
* otherwise.
*/
uint32_t request_alignment;
/*
* Maximum number of bytes that can be discarded at once. Must be multiple
* of pdiscard_alignment, but need not be power of 2. May be 0 if no
* inherent 64-bit limit.
*/
int64_t max_pdiscard;
/*
* Optimal alignment for discard requests in bytes. A power of 2
* is best but not mandatory. Must be a multiple of
* bl.request_alignment, and must be less than max_pdiscard if
* that is set. May be 0 if bl.request_alignment is good enough
*/
uint32_t pdiscard_alignment;
/*
* Maximum number of bytes that can zeroized at once. Must be multiple of
* pwrite_zeroes_alignment. 0 means no limit.
*/
int64_t max_pwrite_zeroes;
/*
* Optimal alignment for write zeroes requests in bytes. A power
* of 2 is best but not mandatory. Must be a multiple of
* bl.request_alignment, and must be less than max_pwrite_zeroes
* if that is set. May be 0 if bl.request_alignment is good
* enough
*/
uint32_t pwrite_zeroes_alignment;
/*
* Optimal transfer length in bytes. A power of 2 is best but not
* mandatory. Must be a multiple of bl.request_alignment, or 0 if
* no preferred size
*/
uint32_t opt_transfer;
/*
* Maximal transfer length in bytes. Need not be power of 2, but
* must be multiple of opt_transfer and bl.request_alignment, or 0
* for no 32-bit limit. For now, anything larger than INT_MAX is
* clamped down.
*/
uint32_t max_transfer;
/*
* Maximal hardware transfer length in bytes. Applies whenever
* transfers to the device bypass the kernel I/O scheduler, for
* example with SG_IO. If larger than max_transfer or if zero,
* blk_get_max_hw_transfer will fall back to max_transfer.
*/
uint64_t max_hw_transfer;
/*
* Maximal number of scatter/gather elements allowed by the hardware.
* Applies whenever transfers to the device bypass the kernel I/O
* scheduler, for example with SG_IO. If larger than max_iov
* or if zero, blk_get_max_hw_iov will fall back to max_iov.
*/
int max_hw_iov;
/* memory alignment, in bytes so that no bounce buffer is needed */
size_t min_mem_alignment;
/* memory alignment, in bytes, for bounce buffer */
size_t opt_mem_alignment;
/* maximum number of iovec elements */
int max_iov;
/*
* true if the length of the underlying file can change, and QEMU
* is expected to adjust automatically. Mostly for CD-ROM drives,
* whose length is zero when the tray is empty (they don't need
* an explicit monitor command to load the disk inside the guest).
*/
bool has_variable_length;
/* device zone model */
BlockZoneModel zoned;
/* zone size expressed in bytes */
uint32_t zone_size;
/* total number of zones */
uint32_t nr_zones;
/* maximum sectors of a zone append write operation */
uint32_t max_append_sectors;
/* maximum number of open zones */
uint32_t max_open_zones;
/* maximum number of active zones */
uint32_t max_active_zones;
uint32_t write_granularity;
} BlockLimits;
typedef struct BdrvOpBlocker BdrvOpBlocker;
typedef struct BdrvAioNotifier {
void (*attached_aio_context)(AioContext *new_context, void *opaque);
void (*detach_aio_context)(void *opaque);
void *opaque;
bool deleted;
QLIST_ENTRY(BdrvAioNotifier) list;
} BdrvAioNotifier;
struct BdrvChildClass {
/*
* If true, bdrv_replace_node() doesn't change the node this BdrvChild
* points to.
*/
bool stay_at_node;
/*
* If true, the parent is a BlockDriverState and bdrv_next_all_states()
* will return it. This information is used for drain_all, where every node
* will be drained separately, so the drain only needs to be propagated to
* non-BDS parents.
*/
bool parent_is_bds;
/*
* Global state (GS) API. These functions run under the BQL.
*
* See include/block/block-global-state.h for more information about
* the GS API.
*/
void (*inherit_options)(BdrvChildRole role, bool parent_is_format,
int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options);
void (*change_media)(BdrvChild *child, bool load);
/*
* Returns a malloced string that describes the parent of the child for a
* human reader. This could be a node-name, BlockBackend name, qdev ID or
* QOM path of the device owning the BlockBackend, job type and ID etc. The
* caller is responsible for freeing the memory.
*/
char *(*get_parent_desc)(BdrvChild *child);
/*
* Notifies the parent that the child has been activated/inactivated (e.g.
* when migration is completing) and it can start/stop requesting
* permissions and doing I/O on it.
*/
void GRAPH_RDLOCK_PTR (*activate)(BdrvChild *child, Error **errp);
int GRAPH_RDLOCK_PTR (*inactivate)(BdrvChild *child);
void GRAPH_WRLOCK_PTR (*attach)(BdrvChild *child);
void GRAPH_WRLOCK_PTR (*detach)(BdrvChild *child);
/*
* If this pair of functions is implemented, the parent doesn't issue new
* requests after returning from .drained_begin() until .drained_end() is
* called.
*
* These functions must not change the graph (and therefore also must not
* call aio_poll(), which could change the graph indirectly).
*
* Note that this can be nested. If drained_begin() was called twice, new
* I/O is allowed only after drained_end() was called twice, too.
*/
void GRAPH_RDLOCK_PTR (*drained_begin)(BdrvChild *child);
void GRAPH_RDLOCK_PTR (*drained_end)(BdrvChild *child);
/*
* Returns whether the parent has pending requests for the child. This
* callback is polled after .drained_begin() has been called until all
* activity on the child has stopped.
*/
bool GRAPH_RDLOCK_PTR (*drained_poll)(BdrvChild *child);
/*
* Notifies the parent that the filename of its child has changed (e.g.
* because the direct child was removed from the backing chain), so that it
* can update its reference.
*/
int (*update_filename)(BdrvChild *child, BlockDriverState *new_base,
const char *filename, Error **errp);
bool (*change_aio_ctx)(BdrvChild *child, AioContext *ctx,
GHashTable *visited, Transaction *tran,
Error **errp);
/*
* I/O API functions. These functions are thread-safe.
*
* See include/block/block-io.h for more information about
* the I/O API.
*/
void (*resize)(BdrvChild *child);
/*
* Returns a name that is supposedly more useful for human users than the
* node name for identifying the node in question (in particular, a BB
* name), or NULL if the parent can't provide a better name.
*/
const char *(*get_name)(BdrvChild *child);
AioContext *(*get_parent_aio_context)(BdrvChild *child);
};
extern const BdrvChildClass child_of_bds;
struct BdrvChild {
BlockDriverState *bs;
char *name;
const BdrvChildClass *klass;
BdrvChildRole role;
void *opaque;
/**
* Granted permissions for operating on this BdrvChild (BLK_PERM_* bitmask)
*/
uint64_t perm;
/**
* Permissions that can still be granted to other users of @bs while this
* BdrvChild is still attached to it. (BLK_PERM_* bitmask)
*/
uint64_t shared_perm;
/*
* This link is frozen: the child can neither be replaced nor
* detached from the parent.
*/
bool frozen;
/*
* True if the parent of this child has been drained by this BdrvChild
* (through klass->drained_*).
*
* It is generally true if bs->quiesce_counter > 0. It may differ while the
* child is entering or leaving a drained section.
*/
bool quiesced_parent;
QLIST_ENTRY(BdrvChild GRAPH_RDLOCK_PTR) next;
QLIST_ENTRY(BdrvChild GRAPH_RDLOCK_PTR) next_parent;
};
/*
* Allows bdrv_co_block_status() to cache one data region for a
* protocol node.
*
* @valid: Whether the cache is valid (should be accessed with atomic
* functions so this can be reset by RCU readers)
* @data_start: Offset where we know (or strongly assume) is data
* @data_end: Offset where the data region ends (which is not necessarily
* the start of a zeroed region)
*/
typedef struct BdrvBlockStatusCache {
struct rcu_head rcu;
bool valid;
int64_t data_start;
int64_t data_end;
} BdrvBlockStatusCache;
struct BlockDriverState {
/*
* Protected by big QEMU lock or read-only after opening. No special
* locking needed during I/O...
*/
int open_flags; /* flags used to open the file, re-used for re-open */
bool encrypted; /* if true, the media is encrypted */
bool sg; /* if true, the device is a /dev/sg* */
bool probed; /* if true, format was probed rather than specified */
bool force_share; /* if true, always allow all shared permissions */
bool implicit; /* if true, this filter node was automatically inserted */
BlockDriver *drv; /* NULL means no media */
void *opaque;
AioContext *aio_context; /* event loop used for fd handlers, timers, etc */
/*
* long-running tasks intended to always use the same AioContext as this
* BDS may register themselves in this list to be notified of changes
* regarding this BDS's context
*/
QLIST_HEAD(, BdrvAioNotifier) aio_notifiers;
bool walking_aio_notifiers; /* to make removal during iteration safe */
char filename[PATH_MAX];
/*
* If not empty, this image is a diff in relation to backing_file.
* Note that this is the name given in the image header and
* therefore may or may not be equal to .backing->bs->filename.
* If this field contains a relative path, it is to be resolved
* relatively to the overlay's location.
*/
char backing_file[PATH_MAX];
/*
* The backing filename indicated by the image header. Contrary
* to backing_file, if we ever open this file, auto_backing_file
* is replaced by the resulting BDS's filename (i.e. after a
* bdrv_refresh_filename() run).
*/
char auto_backing_file[PATH_MAX];
char backing_format[16]; /* if non-zero and backing_file exists */
QDict *full_open_options;
char exact_filename[PATH_MAX];
/* I/O Limits */
BlockLimits bl;
/*
* Flags honored during pread
*/
BdrvRequestFlags supported_read_flags;
/*
* Flags honored during pwrite (so far: BDRV_REQ_FUA,
* BDRV_REQ_WRITE_UNCHANGED).
* If a driver does not support BDRV_REQ_WRITE_UNCHANGED, those
* writes will be issued as normal writes without the flag set.
* This is important to note for drivers that do not explicitly
* request a WRITE permission for their children and instead take
* the same permissions as their parent did (this is commonly what
* block filters do). Such drivers have to be aware that the
* parent may have taken a WRITE_UNCHANGED permission only and is
* issuing such requests. Drivers either must make sure that
* these requests do not result in plain WRITE accesses (usually
* by supporting BDRV_REQ_WRITE_UNCHANGED, and then forwarding
* every incoming write request as-is, including potentially that
* flag), or they have to explicitly take the WRITE permission for
* their children.
*/
BdrvRequestFlags supported_write_flags;
/*
* Flags honored during pwrite_zeroes (so far: BDRV_REQ_FUA,
* BDRV_REQ_MAY_UNMAP, BDRV_REQ_WRITE_UNCHANGED)
*/
BdrvRequestFlags supported_zero_flags;
/*
* Flags honoured during truncate (so far: BDRV_REQ_ZERO_WRITE).
*
* If BDRV_REQ_ZERO_WRITE is given, the truncate operation must make sure
* that any added space reads as all zeros. If this can't be guaranteed,
* the operation must fail.
*/
BdrvRequestFlags supported_truncate_flags;
/* the following member gives a name to every node on the bs graph. */
char node_name[32];
/* element of the list of named nodes building the graph */
QTAILQ_ENTRY(BlockDriverState) node_list;
/* element of the list of all BlockDriverStates (all_bdrv_states) */
QTAILQ_ENTRY(BlockDriverState) bs_list;
/* element of the list of monitor-owned BDS */
QTAILQ_ENTRY(BlockDriverState) monitor_list;
int refcnt;
/* operation blockers. Protected by BQL. */
QLIST_HEAD(, BdrvOpBlocker) op_blockers[BLOCK_OP_TYPE_MAX];
/*
* The node that this node inherited default options from (and a reopen on
* which can affect this node by changing these defaults). This is always a
* parent node of this node.
*/
BlockDriverState *inherits_from;
/*
* @backing and @file are some of @children or NULL. All these three fields
* (@file, @backing and @children) are modified only in
* bdrv_child_cb_attach() and bdrv_child_cb_detach().
*
* See also comment in include/block/block.h, to learn how backing and file
* are connected with BdrvChildRole.
*/
QLIST_HEAD(, BdrvChild GRAPH_RDLOCK_PTR) children;
BdrvChild * GRAPH_RDLOCK_PTR backing;
BdrvChild *file;
QLIST_HEAD(, BdrvChild GRAPH_RDLOCK_PTR) parents;
QDict *options;
QDict *explicit_options;
BlockdevDetectZeroesOptions detect_zeroes;
/* The error object in use for blocking operations on backing_hd */
Error *backing_blocker;
/* Protected by AioContext lock */
/*
* If we are reading a disk image, give its size in sectors.
* Generally read-only; it is written to by load_snapshot and
* save_snaphost, but the block layer is quiescent during those.
*/
int64_t total_sectors;
/* threshold limit for writes, in bytes. "High water mark". */
uint64_t write_threshold_offset;
/*
* Writing to the list requires the BQL _and_ the dirty_bitmap_mutex.
* Reading from the list can be done with either the BQL or the
* dirty_bitmap_mutex. Modifying a bitmap only requires
* dirty_bitmap_mutex.
*/
QemuMutex dirty_bitmap_mutex;
QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps;
/* Offset after the highest byte written to */
Stat64 wr_highest_offset;
/*
* If true, copy read backing sectors into image. Can be >1 if more
* than one client has requested copy-on-read. Accessed with atomic
* ops.
*/
int copy_on_read;
/*
* number of in-flight requests; overall and serialising.
* Accessed with atomic ops.
*/
unsigned int in_flight;
unsigned int serialising_in_flight;
/* do we need to tell the quest if we have a volatile write cache? */
int enable_write_cache;
/* Accessed with atomic ops. */
int quiesce_counter;
unsigned int write_gen; /* Current data generation */
/* Protected by reqs_lock. */
QemuMutex reqs_lock;
QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;
CoQueue flush_queue; /* Serializing flush queue */
bool active_flush_req; /* Flush request in flight? */
/* Only read/written by whoever has set active_flush_req to true. */
unsigned int flushed_gen; /* Flushed write generation */
/* BdrvChild links to this node may never be frozen */
bool never_freeze;
/* Lock for block-status cache RCU writers */
CoMutex bsc_modify_lock;
/* Always non-NULL, but must only be dereferenced under an RCU read guard */
BdrvBlockStatusCache *block_status_cache;
/* array of write pointers' location of each zone in the zoned device. */
BlockZoneWps *wps;
};
struct BlockBackendRootState {
int open_flags;
BlockdevDetectZeroesOptions detect_zeroes;
};
typedef enum BlockMirrorBackingMode {
/*
* Reuse the existing backing chain from the source for the target.
* - sync=full: Set backing BDS to NULL.
* - sync=top: Use source's backing BDS.
* - sync=none: Use source as the backing BDS.
*/
MIRROR_SOURCE_BACKING_CHAIN,
/* Open the target's backing chain completely anew */
MIRROR_OPEN_BACKING_CHAIN,
/* Do not change the target's backing BDS after job completion */
MIRROR_LEAVE_BACKING_CHAIN,
} BlockMirrorBackingMode;
/*
* Essential block drivers which must always be statically linked into qemu, and
* which therefore can be accessed without using bdrv_find_format()
*/
extern BlockDriver bdrv_file;
extern BlockDriver bdrv_raw;
extern BlockDriver bdrv_qcow2;
extern unsigned int bdrv_drain_all_count;
extern QemuOptsList bdrv_create_opts_simple;
/*
* Common functions that are neither I/O nor Global State.
*
* See include/block/block-common.h for more information about
* the Common API.
*/
static inline BlockDriverState *child_bs(BdrvChild *child)
{
return child ? child->bs : NULL;
}
int bdrv_check_request(int64_t offset, int64_t bytes, Error **errp);
char *create_tmp_file(Error **errp);
void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix,
QDict *options);
int bdrv_check_qiov_request(int64_t offset, int64_t bytes,
QEMUIOVector *qiov, size_t qiov_offset,
Error **errp);
#ifdef _WIN32
int is_windows_drive(const char *filename);
#endif
#endif /* BLOCK_INT_COMMON_H */