b94a261057
The block layer generally keeps the size of an image cached in bs->total_sectors so that it doesn't have to perform expensive operations to get the size whenever it needs it. This doesn't work however when using a backend that can change its size without qemu being aware of it, i.e. passthrough of removable media like CD-ROMs or floppy disks. For this reason, the caching is disabled when a removable device is used. It is obvious that checking whether the _guest_ device has removable media isn't the right thing to do when we want to know whether the size of the host backend can change. To make things worse, non-top-level BlockDriverStates never have any device attached, which makes qemu assume they are removable, so drv->bdrv_getlength() is always called on the protocol layer. In the case of raw-posix, this causes unnecessary lseek() system calls, which turned out to be rather expensive. This patch completely changes the logic and disables bs->total_sectors caching only for certain block driver types, for which a size change is expected: host_cdrom and host_floppy on POSIX, host_device on win32; also the raw format in case it sits on top of one of these protocols, but in the common case the nested bdrv_getlength() call on the protocol driver will use the cache again and avoid an expensive drv->bdrv_getlength() call. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
434 lines
17 KiB
C
434 lines
17 KiB
C
/*
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* QEMU System Emulator block driver
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*
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* Copyright (c) 2003 Fabrice Bellard
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#ifndef BLOCK_INT_H
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#define BLOCK_INT_H
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#include "block/block.h"
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#include "qemu/option.h"
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#include "qemu/queue.h"
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#include "block/coroutine.h"
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#include "qemu/timer.h"
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#include "qapi-types.h"
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#include "qapi/qmp/qerror.h"
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#include "monitor/monitor.h"
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#include "qemu/hbitmap.h"
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#include "block/snapshot.h"
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#include "qemu/main-loop.h"
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#include "qemu/throttle.h"
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#define BLOCK_FLAG_ENCRYPT 1
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#define BLOCK_FLAG_COMPAT6 4
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#define BLOCK_FLAG_LAZY_REFCOUNTS 8
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#define BLOCK_OPT_SIZE "size"
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#define BLOCK_OPT_ENCRYPT "encryption"
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#define BLOCK_OPT_COMPAT6 "compat6"
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#define BLOCK_OPT_BACKING_FILE "backing_file"
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#define BLOCK_OPT_BACKING_FMT "backing_fmt"
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#define BLOCK_OPT_CLUSTER_SIZE "cluster_size"
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#define BLOCK_OPT_TABLE_SIZE "table_size"
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#define BLOCK_OPT_PREALLOC "preallocation"
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#define BLOCK_OPT_SUBFMT "subformat"
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#define BLOCK_OPT_COMPAT_LEVEL "compat"
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#define BLOCK_OPT_LAZY_REFCOUNTS "lazy_refcounts"
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#define BLOCK_OPT_ADAPTER_TYPE "adapter_type"
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typedef struct BdrvTrackedRequest {
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BlockDriverState *bs;
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int64_t sector_num;
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int nb_sectors;
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bool is_write;
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QLIST_ENTRY(BdrvTrackedRequest) list;
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Coroutine *co; /* owner, used for deadlock detection */
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CoQueue wait_queue; /* coroutines blocked on this request */
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} BdrvTrackedRequest;
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struct BlockDriver {
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const char *format_name;
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int instance_size;
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/* if not defined external snapshots are allowed
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* future block filters will query their children to build the response
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*/
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ExtSnapshotPerm (*bdrv_check_ext_snapshot)(BlockDriverState *bs);
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int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename);
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int (*bdrv_probe_device)(const char *filename);
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/* Any driver implementing this callback is expected to be able to handle
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* NULL file names in its .bdrv_open() implementation */
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void (*bdrv_parse_filename)(const char *filename, QDict *options, Error **errp);
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/* Drivers not implementing bdrv_parse_filename nor bdrv_open should have
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* this field set to true, except ones that are defined only by their
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* child's bs.
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* An example of the last type will be the quorum block driver.
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*/
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bool bdrv_needs_filename;
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/* For handling image reopen for split or non-split files */
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int (*bdrv_reopen_prepare)(BDRVReopenState *reopen_state,
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BlockReopenQueue *queue, Error **errp);
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void (*bdrv_reopen_commit)(BDRVReopenState *reopen_state);
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void (*bdrv_reopen_abort)(BDRVReopenState *reopen_state);
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int (*bdrv_open)(BlockDriverState *bs, QDict *options, int flags,
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Error **errp);
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int (*bdrv_file_open)(BlockDriverState *bs, QDict *options, int flags,
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Error **errp);
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int (*bdrv_read)(BlockDriverState *bs, int64_t sector_num,
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uint8_t *buf, int nb_sectors);
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int (*bdrv_write)(BlockDriverState *bs, int64_t sector_num,
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const uint8_t *buf, int nb_sectors);
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void (*bdrv_close)(BlockDriverState *bs);
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void (*bdrv_rebind)(BlockDriverState *bs);
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int (*bdrv_create)(const char *filename, QEMUOptionParameter *options,
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Error **errp);
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int (*bdrv_set_key)(BlockDriverState *bs, const char *key);
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int (*bdrv_make_empty)(BlockDriverState *bs);
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/* aio */
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BlockDriverAIOCB *(*bdrv_aio_readv)(BlockDriverState *bs,
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int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
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BlockDriverCompletionFunc *cb, void *opaque);
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BlockDriverAIOCB *(*bdrv_aio_writev)(BlockDriverState *bs,
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int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
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BlockDriverCompletionFunc *cb, void *opaque);
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BlockDriverAIOCB *(*bdrv_aio_flush)(BlockDriverState *bs,
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BlockDriverCompletionFunc *cb, void *opaque);
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BlockDriverAIOCB *(*bdrv_aio_discard)(BlockDriverState *bs,
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int64_t sector_num, int nb_sectors,
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BlockDriverCompletionFunc *cb, void *opaque);
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int coroutine_fn (*bdrv_co_readv)(BlockDriverState *bs,
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int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
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int coroutine_fn (*bdrv_co_writev)(BlockDriverState *bs,
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int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
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/*
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* Efficiently zero a region of the disk image. Typically an image format
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* would use a compact metadata representation to implement this. This
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* function pointer may be NULL and .bdrv_co_writev() will be called
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* instead.
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*/
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int coroutine_fn (*bdrv_co_write_zeroes)(BlockDriverState *bs,
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int64_t sector_num, int nb_sectors);
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int coroutine_fn (*bdrv_co_discard)(BlockDriverState *bs,
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int64_t sector_num, int nb_sectors);
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int64_t coroutine_fn (*bdrv_co_get_block_status)(BlockDriverState *bs,
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int64_t sector_num, int nb_sectors, int *pnum);
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/*
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* Invalidate any cached meta-data.
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*/
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void (*bdrv_invalidate_cache)(BlockDriverState *bs);
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/*
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* Flushes all data that was already written to the OS all the way down to
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* the disk (for example raw-posix calls fsync()).
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*/
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int coroutine_fn (*bdrv_co_flush_to_disk)(BlockDriverState *bs);
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/*
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* Flushes all internal caches to the OS. The data may still sit in a
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* writeback cache of the host OS, but it will survive a crash of the qemu
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* process.
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*/
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int coroutine_fn (*bdrv_co_flush_to_os)(BlockDriverState *bs);
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const char *protocol_name;
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int (*bdrv_truncate)(BlockDriverState *bs, int64_t offset);
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int64_t (*bdrv_getlength)(BlockDriverState *bs);
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bool has_variable_length;
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int64_t (*bdrv_get_allocated_file_size)(BlockDriverState *bs);
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int (*bdrv_write_compressed)(BlockDriverState *bs, int64_t sector_num,
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const uint8_t *buf, int nb_sectors);
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int (*bdrv_snapshot_create)(BlockDriverState *bs,
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QEMUSnapshotInfo *sn_info);
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int (*bdrv_snapshot_goto)(BlockDriverState *bs,
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const char *snapshot_id);
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int (*bdrv_snapshot_delete)(BlockDriverState *bs,
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const char *snapshot_id,
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const char *name,
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Error **errp);
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int (*bdrv_snapshot_list)(BlockDriverState *bs,
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QEMUSnapshotInfo **psn_info);
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int (*bdrv_snapshot_load_tmp)(BlockDriverState *bs,
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const char *snapshot_name);
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int (*bdrv_get_info)(BlockDriverState *bs, BlockDriverInfo *bdi);
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ImageInfoSpecific *(*bdrv_get_specific_info)(BlockDriverState *bs);
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int (*bdrv_save_vmstate)(BlockDriverState *bs, QEMUIOVector *qiov,
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int64_t pos);
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int (*bdrv_load_vmstate)(BlockDriverState *bs, uint8_t *buf,
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int64_t pos, int size);
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int (*bdrv_change_backing_file)(BlockDriverState *bs,
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const char *backing_file, const char *backing_fmt);
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/* removable device specific */
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int (*bdrv_is_inserted)(BlockDriverState *bs);
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int (*bdrv_media_changed)(BlockDriverState *bs);
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void (*bdrv_eject)(BlockDriverState *bs, bool eject_flag);
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void (*bdrv_lock_medium)(BlockDriverState *bs, bool locked);
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/* to control generic scsi devices */
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int (*bdrv_ioctl)(BlockDriverState *bs, unsigned long int req, void *buf);
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BlockDriverAIOCB *(*bdrv_aio_ioctl)(BlockDriverState *bs,
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unsigned long int req, void *buf,
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BlockDriverCompletionFunc *cb, void *opaque);
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/* List of options for creating images, terminated by name == NULL */
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QEMUOptionParameter *create_options;
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/*
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* Returns 0 for completed check, -errno for internal errors.
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* The check results are stored in result.
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*/
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int (*bdrv_check)(BlockDriverState* bs, BdrvCheckResult *result,
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BdrvCheckMode fix);
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int (*bdrv_amend_options)(BlockDriverState *bs,
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QEMUOptionParameter *options);
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void (*bdrv_debug_event)(BlockDriverState *bs, BlkDebugEvent event);
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/* TODO Better pass a option string/QDict/QemuOpts to add any rule? */
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int (*bdrv_debug_breakpoint)(BlockDriverState *bs, const char *event,
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const char *tag);
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int (*bdrv_debug_resume)(BlockDriverState *bs, const char *tag);
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bool (*bdrv_debug_is_suspended)(BlockDriverState *bs, const char *tag);
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/*
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* Returns 1 if newly created images are guaranteed to contain only
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* zeros, 0 otherwise.
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*/
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int (*bdrv_has_zero_init)(BlockDriverState *bs);
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QLIST_ENTRY(BlockDriver) list;
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};
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/*
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* Note: the function bdrv_append() copies and swaps contents of
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* BlockDriverStates, so if you add new fields to this struct, please
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* inspect bdrv_append() to determine if the new fields need to be
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* copied as well.
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*/
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struct BlockDriverState {
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int64_t total_sectors; /* if we are reading a disk image, give its
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size in sectors */
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int read_only; /* if true, the media is read only */
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int open_flags; /* flags used to open the file, re-used for re-open */
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int encrypted; /* if true, the media is encrypted */
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int valid_key; /* if true, a valid encryption key has been set */
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int sg; /* if true, the device is a /dev/sg* */
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int copy_on_read; /* if true, copy read backing sectors into image
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note this is a reference count */
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BlockDriver *drv; /* NULL means no media */
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void *opaque;
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void *dev; /* attached device model, if any */
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/* TODO change to DeviceState when all users are qdevified */
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const BlockDevOps *dev_ops;
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void *dev_opaque;
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char filename[1024];
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char backing_file[1024]; /* if non zero, the image is a diff of
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this file image */
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char backing_format[16]; /* if non-zero and backing_file exists */
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int is_temporary;
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BlockDriverState *backing_hd;
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BlockDriverState *file;
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NotifierList close_notifiers;
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/* Callback before write request is processed */
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NotifierWithReturnList before_write_notifiers;
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/* number of in-flight copy-on-read requests */
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unsigned int copy_on_read_in_flight;
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/* I/O throttling */
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ThrottleState throttle_state;
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CoQueue throttled_reqs[2];
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bool io_limits_enabled;
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/* I/O stats (display with "info blockstats"). */
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uint64_t nr_bytes[BDRV_MAX_IOTYPE];
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uint64_t nr_ops[BDRV_MAX_IOTYPE];
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uint64_t total_time_ns[BDRV_MAX_IOTYPE];
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uint64_t wr_highest_sector;
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/* Whether the disk can expand beyond total_sectors */
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int growable;
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/* Whether produces zeros when read beyond eof */
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bool zero_beyond_eof;
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/* the memory alignment required for the buffers handled by this driver */
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int buffer_alignment;
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/* do we need to tell the quest if we have a volatile write cache? */
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int enable_write_cache;
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/* NOTE: the following infos are only hints for real hardware
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drivers. They are not used by the block driver */
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BlockdevOnError on_read_error, on_write_error;
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bool iostatus_enabled;
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BlockDeviceIoStatus iostatus;
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char device_name[32];
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HBitmap *dirty_bitmap;
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int refcnt;
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int in_use; /* users other than guest access, eg. block migration */
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QTAILQ_ENTRY(BlockDriverState) list;
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QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;
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/* long-running background operation */
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BlockJob *job;
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QDict *options;
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};
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int get_tmp_filename(char *filename, int size);
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void bdrv_set_io_limits(BlockDriverState *bs,
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ThrottleConfig *cfg);
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/**
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* bdrv_add_before_write_notifier:
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*
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* Register a callback that is invoked before write requests are processed but
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* after any throttling or waiting for overlapping requests.
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*/
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void bdrv_add_before_write_notifier(BlockDriverState *bs,
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NotifierWithReturn *notifier);
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/**
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* bdrv_get_aio_context:
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*
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* Returns: the currently bound #AioContext
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*/
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AioContext *bdrv_get_aio_context(BlockDriverState *bs);
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#ifdef _WIN32
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int is_windows_drive(const char *filename);
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#endif
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void bdrv_emit_qmp_error_event(const BlockDriverState *bdrv,
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enum MonitorEvent ev,
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BlockErrorAction action, bool is_read);
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/**
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* stream_start:
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* @bs: Block device to operate on.
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* @base: Block device that will become the new base, or %NULL to
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* flatten the whole backing file chain onto @bs.
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* @base_id: The file name that will be written to @bs as the new
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* backing file if the job completes. Ignored if @base is %NULL.
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* @speed: The maximum speed, in bytes per second, or 0 for unlimited.
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* @on_error: The action to take upon error.
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* @cb: Completion function for the job.
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* @opaque: Opaque pointer value passed to @cb.
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* @errp: Error object.
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*
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* Start a streaming operation on @bs. Clusters that are unallocated
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* in @bs, but allocated in any image between @base and @bs (both
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* exclusive) will be written to @bs. At the end of a successful
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* streaming job, the backing file of @bs will be changed to
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* @base_id in the written image and to @base in the live BlockDriverState.
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*/
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void stream_start(BlockDriverState *bs, BlockDriverState *base,
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const char *base_id, int64_t speed, BlockdevOnError on_error,
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BlockDriverCompletionFunc *cb,
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void *opaque, Error **errp);
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/**
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* commit_start:
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* @bs: Top Block device
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* @base: Block device that will be written into, and become the new top
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* @speed: The maximum speed, in bytes per second, or 0 for unlimited.
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* @on_error: The action to take upon error.
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* @cb: Completion function for the job.
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* @opaque: Opaque pointer value passed to @cb.
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* @errp: Error object.
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*
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*/
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void commit_start(BlockDriverState *bs, BlockDriverState *base,
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BlockDriverState *top, int64_t speed,
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BlockdevOnError on_error, BlockDriverCompletionFunc *cb,
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void *opaque, Error **errp);
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/*
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* mirror_start:
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* @bs: Block device to operate on.
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* @target: Block device to write to.
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* @speed: The maximum speed, in bytes per second, or 0 for unlimited.
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* @granularity: The chosen granularity for the dirty bitmap.
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* @buf_size: The amount of data that can be in flight at one time.
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* @mode: Whether to collapse all images in the chain to the target.
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* @on_source_error: The action to take upon error reading from the source.
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* @on_target_error: The action to take upon error writing to the target.
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* @cb: Completion function for the job.
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* @opaque: Opaque pointer value passed to @cb.
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* @errp: Error object.
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*
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* Start a mirroring operation on @bs. Clusters that are allocated
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* in @bs will be written to @bs until the job is cancelled or
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* manually completed. At the end of a successful mirroring job,
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* @bs will be switched to read from @target.
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*/
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void mirror_start(BlockDriverState *bs, BlockDriverState *target,
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int64_t speed, int64_t granularity, int64_t buf_size,
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MirrorSyncMode mode, BlockdevOnError on_source_error,
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BlockdevOnError on_target_error,
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BlockDriverCompletionFunc *cb,
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void *opaque, Error **errp);
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/*
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* backup_start:
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* @bs: Block device to operate on.
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* @target: Block device to write to.
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* @speed: The maximum speed, in bytes per second, or 0 for unlimited.
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* @sync_mode: What parts of the disk image should be copied to the destination.
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* @on_source_error: The action to take upon error reading from the source.
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* @on_target_error: The action to take upon error writing to the target.
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* @cb: Completion function for the job.
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* @opaque: Opaque pointer value passed to @cb.
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*
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* Start a backup operation on @bs. Clusters in @bs are written to @target
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* until the job is cancelled or manually completed.
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*/
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void backup_start(BlockDriverState *bs, BlockDriverState *target,
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int64_t speed, MirrorSyncMode sync_mode,
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BlockdevOnError on_source_error,
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BlockdevOnError on_target_error,
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BlockDriverCompletionFunc *cb, void *opaque,
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Error **errp);
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#endif /* BLOCK_INT_H */
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