include/block/block_int.h

   1 /*
   2  * QEMU System Emulator block driver
   3  *
   4  * Copyright (c) 2003 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24 #ifndef BLOCK_INT_H
  25 #define BLOCK_INT_H
  26
  27 #include "block/block.h"
  28 #include "qemu/option.h"
  29 #include "qemu/queue.h"
  30 #include "block/coroutine.h"
  31 #include "qemu/timer.h"
  32 #include "qapi-types.h"
  33 #include "qapi/qmp/qerror.h"
  34 #include "monitor/monitor.h"
  35 #include "qemu/hbitmap.h"
  36 #include "block/snapshot.h"
  37 #include "qemu/main-loop.h"
  38 #include "qemu/throttle.h"
  39
  40 #define BLOCK_FLAG_ENCRYPT          1
  41 #define BLOCK_FLAG_COMPAT6          4
  42 #define BLOCK_FLAG_LAZY_REFCOUNTS   8
  43
  44 #define BLOCK_OPT_SIZE              "size"
  45 #define BLOCK_OPT_ENCRYPT           "encryption"
  46 #define BLOCK_OPT_COMPAT6           "compat6"
  47 #define BLOCK_OPT_BACKING_FILE      "backing_file"
  48 #define BLOCK_OPT_BACKING_FMT       "backing_fmt"
  49 #define BLOCK_OPT_CLUSTER_SIZE      "cluster_size"
  50 #define BLOCK_OPT_TABLE_SIZE        "table_size"
  51 #define BLOCK_OPT_PREALLOC          "preallocation"
  52 #define BLOCK_OPT_SUBFMT            "subformat"
  53 #define BLOCK_OPT_COMPAT_LEVEL      "compat"
  54 #define BLOCK_OPT_LAZY_REFCOUNTS    "lazy_refcounts"
  55 #define BLOCK_OPT_ADAPTER_TYPE      "adapter_type"
  56 #define BLOCK_OPT_REDUNDANCY        "redundancy"
  57 #define BLOCK_OPT_NOCOW             "nocow"
  58
  59 typedef struct BdrvTrackedRequest {
  60     BlockDriverState *bs;
  61     int64_t offset;
  62     unsigned int bytes;
  63     bool is_write;
  64
  65     bool serialising;
  66     int64_t overlap_offset;
  67     unsigned int overlap_bytes;
  68
  69     QLIST_ENTRY(BdrvTrackedRequest) list;
  70     Coroutine *co; /* owner, used for deadlock detection */
  71     CoQueue wait_queue; /* coroutines blocked on this request */
  72
  73     struct BdrvTrackedRequest *waiting_for;
  74 } BdrvTrackedRequest;
  75
  76 struct BlockDriver {
  77     const char *format_name;
  78     int instance_size;
  79
  80     /* set to true if the BlockDriver is a block filter */
  81     bool is_filter;
  82     /* for snapshots block filter like Quorum can implement the
  83      * following recursive callback.
  84      * It's purpose is to recurse on the filter children while calling
  85      * bdrv_recurse_is_first_non_filter on them.
  86      * For a sample implementation look in the future Quorum block filter.
  87      */
  88     bool (*bdrv_recurse_is_first_non_filter)(BlockDriverState *bs,
  89                                              BlockDriverState *candidate);
  90
  91     int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename);
  92     int (*bdrv_probe_device)(const char *filename);
  93
  94     /* Any driver implementing this callback is expected to be able to handle
  95      * NULL file names in its .bdrv_open() implementation */
  96     void (*bdrv_parse_filename)(const char *filename, QDict *options, Error **errp);
  97     /* Drivers not implementing bdrv_parse_filename nor bdrv_open should have
  98      * this field set to true, except ones that are defined only by their
  99      * child's bs.
 100      * An example of the last type will be the quorum block driver.
 101      */
 102     bool bdrv_needs_filename;
 103
 104     /* Set if a driver can support backing files */
 105     bool supports_backing;
 106
 107     /* For handling image reopen for split or non-split files */
 108     int (*bdrv_reopen_prepare)(BDRVReopenState *reopen_state,
 109                                BlockReopenQueue *queue, Error **errp);
 110     void (*bdrv_reopen_commit)(BDRVReopenState *reopen_state);
 111     void (*bdrv_reopen_abort)(BDRVReopenState *reopen_state);
 112
 113     int (*bdrv_open)(BlockDriverState *bs, QDict *options, int flags,
 114                      Error **errp);
 115     int (*bdrv_file_open)(BlockDriverState *bs, QDict *options, int flags,
 116                           Error **errp);
 117     int (*bdrv_read)(BlockDriverState *bs, int64_t sector_num,
 118                      uint8_t *buf, int nb_sectors);
 119     int (*bdrv_write)(BlockDriverState *bs, int64_t sector_num,
 120                       const uint8_t *buf, int nb_sectors);
 121     void (*bdrv_close)(BlockDriverState *bs);
 122     void (*bdrv_rebind)(BlockDriverState *bs);
 123     int (*bdrv_create)(const char *filename, QemuOpts *opts, Error **errp);
 124     int (*bdrv_set_key)(BlockDriverState *bs, const char *key);
 125     int (*bdrv_make_empty)(BlockDriverState *bs);
 126     /* aio */
 127     BlockDriverAIOCB *(*bdrv_aio_readv)(BlockDriverState *bs,
 128         int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
 129         BlockDriverCompletionFunc *cb, void *opaque);
 130     BlockDriverAIOCB *(*bdrv_aio_writev)(BlockDriverState *bs,
 131         int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
 132         BlockDriverCompletionFunc *cb, void *opaque);
 133     BlockDriverAIOCB *(*bdrv_aio_flush)(BlockDriverState *bs,
 134         BlockDriverCompletionFunc *cb, void *opaque);
 135     BlockDriverAIOCB *(*bdrv_aio_discard)(BlockDriverState *bs,
 136         int64_t sector_num, int nb_sectors,
 137         BlockDriverCompletionFunc *cb, void *opaque);
 138
 139     int coroutine_fn (*bdrv_co_readv)(BlockDriverState *bs,
 140         int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
 141     int coroutine_fn (*bdrv_co_writev)(BlockDriverState *bs,
 142         int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
 143     /*
 144      * Efficiently zero a region of the disk image.  Typically an image format
 145      * would use a compact metadata representation to implement this.  This
 146      * function pointer may be NULL and .bdrv_co_writev() will be called
 147      * instead.
 148      */
 149     int coroutine_fn (*bdrv_co_write_zeroes)(BlockDriverState *bs,
 150         int64_t sector_num, int nb_sectors, BdrvRequestFlags flags);
 151     int coroutine_fn (*bdrv_co_discard)(BlockDriverState *bs,
 152         int64_t sector_num, int nb_sectors);
 153     int64_t coroutine_fn (*bdrv_co_get_block_status)(BlockDriverState *bs,
 154         int64_t sector_num, int nb_sectors, int *pnum);
 155
 156     /*
 157      * Invalidate any cached meta-data.
 158      */
 159     void (*bdrv_invalidate_cache)(BlockDriverState *bs, Error **errp);
 160
 161     /*
 162      * Flushes all data that was already written to the OS all the way down to
 163      * the disk (for example raw-posix calls fsync()).
 164      */
 165     int coroutine_fn (*bdrv_co_flush_to_disk)(BlockDriverState *bs);
 166
 167     /*
 168      * Flushes all internal caches to the OS. The data may still sit in a
 169      * writeback cache of the host OS, but it will survive a crash of the qemu
 170      * process.
 171      */
 172     int coroutine_fn (*bdrv_co_flush_to_os)(BlockDriverState *bs);
 173
 174     const char *protocol_name;
 175     int (*bdrv_truncate)(BlockDriverState *bs, int64_t offset);
 176
 177     int64_t (*bdrv_getlength)(BlockDriverState *bs);
 178     bool has_variable_length;
 179     int64_t (*bdrv_get_allocated_file_size)(BlockDriverState *bs);
 180
 181     int (*bdrv_write_compressed)(BlockDriverState *bs, int64_t sector_num,
 182                                  const uint8_t *buf, int nb_sectors);
 183
 184     int (*bdrv_snapshot_create)(BlockDriverState *bs,
 185                                 QEMUSnapshotInfo *sn_info);
 186     int (*bdrv_snapshot_goto)(BlockDriverState *bs,
 187                               const char *snapshot_id);
 188     int (*bdrv_snapshot_delete)(BlockDriverState *bs,
 189                                 const char *snapshot_id,
 190                                 const char *name,
 191                                 Error **errp);
 192     int (*bdrv_snapshot_list)(BlockDriverState *bs,
 193                               QEMUSnapshotInfo **psn_info);
 194     int (*bdrv_snapshot_load_tmp)(BlockDriverState *bs,
 195                                   const char *snapshot_id,
 196                                   const char *name,
 197                                   Error **errp);
 198     int (*bdrv_get_info)(BlockDriverState *bs, BlockDriverInfo *bdi);
 199     ImageInfoSpecific *(*bdrv_get_specific_info)(BlockDriverState *bs);
 200
 201     int (*bdrv_save_vmstate)(BlockDriverState *bs, QEMUIOVector *qiov,
 202                              int64_t pos);
 203     int (*bdrv_load_vmstate)(BlockDriverState *bs, uint8_t *buf,
 204                              int64_t pos, int size);
 205
 206     int (*bdrv_change_backing_file)(BlockDriverState *bs,
 207         const char *backing_file, const char *backing_fmt);
 208
 209     /* removable device specific */
 210     int (*bdrv_is_inserted)(BlockDriverState *bs);
 211     int (*bdrv_media_changed)(BlockDriverState *bs);
 212     void (*bdrv_eject)(BlockDriverState *bs, bool eject_flag);
 213     void (*bdrv_lock_medium)(BlockDriverState *bs, bool locked);
 214
 215     /* to control generic scsi devices */
 216     int (*bdrv_ioctl)(BlockDriverState *bs, unsigned long int req, void *buf);
 217     BlockDriverAIOCB *(*bdrv_aio_ioctl)(BlockDriverState *bs,
 218         unsigned long int req, void *buf,
 219         BlockDriverCompletionFunc *cb, void *opaque);
 220
 221     /* List of options for creating images, terminated by name == NULL */
 222     QemuOptsList *create_opts;
 223
 224     /*
 225      * Returns 0 for completed check, -errno for internal errors.
 226      * The check results are stored in result.
 227      */
 228     int (*bdrv_check)(BlockDriverState* bs, BdrvCheckResult *result,
 229         BdrvCheckMode fix);
 230
 231     int (*bdrv_amend_options)(BlockDriverState *bs, QemuOpts *opts);
 232
 233     void (*bdrv_debug_event)(BlockDriverState *bs, BlkDebugEvent event);
 234
 235     /* TODO Better pass a option string/QDict/QemuOpts to add any rule? */
 236     int (*bdrv_debug_breakpoint)(BlockDriverState *bs, const char *event,
 237         const char *tag);
 238     int (*bdrv_debug_remove_breakpoint)(BlockDriverState *bs,
 239         const char *tag);
 240     int (*bdrv_debug_resume)(BlockDriverState *bs, const char *tag);
 241     bool (*bdrv_debug_is_suspended)(BlockDriverState *bs, const char *tag);
 242
 243     void (*bdrv_refresh_limits)(BlockDriverState *bs, Error **errp);
 244
 245     /*
 246      * Returns 1 if newly created images are guaranteed to contain only
 247      * zeros, 0 otherwise.
 248      */
 249     int (*bdrv_has_zero_init)(BlockDriverState *bs);
 250
 251     /* Remove fd handlers, timers, and other event loop callbacks so the event
 252      * loop is no longer in use.  Called with no in-flight requests and in
 253      * depth-first traversal order with parents before child nodes.
 254      */
 255     void (*bdrv_detach_aio_context)(BlockDriverState *bs);
 256
 257     /* Add fd handlers, timers, and other event loop callbacks so I/O requests
 258      * can be processed again.  Called with no in-flight requests and in
 259      * depth-first traversal order with child nodes before parent nodes.
 260      */
 261     void (*bdrv_attach_aio_context)(BlockDriverState *bs,
 262                                     AioContext *new_context);
 263
 264     /* io queue for linux-aio */
 265     void (*bdrv_io_plug)(BlockDriverState *bs);
 266     void (*bdrv_io_unplug)(BlockDriverState *bs);
 267     void (*bdrv_flush_io_queue)(BlockDriverState *bs);
 268
 269     QLIST_ENTRY(BlockDriver) list;
 270 };
 271
 272 typedef struct BlockLimits {
 273     /* maximum number of sectors that can be discarded at once */
 274     int max_discard;
 275
 276     /* optimal alignment for discard requests in sectors */
 277     int64_t discard_alignment;
 278
 279     /* maximum number of sectors that can zeroized at once */
 280     int max_write_zeroes;
 281
 282     /* optimal alignment for write zeroes requests in sectors */
 283     int64_t write_zeroes_alignment;
 284
 285     /* optimal transfer length in sectors */
 286     int opt_transfer_length;
 287
 288     /* memory alignment so that no bounce buffer is needed */
 289     size_t opt_mem_alignment;
 290 } BlockLimits;
 291
 292 typedef struct BdrvOpBlocker BdrvOpBlocker;
 293
 294 /*
 295  * Note: the function bdrv_append() copies and swaps contents of
 296  * BlockDriverStates, so if you add new fields to this struct, please
 297  * inspect bdrv_append() to determine if the new fields need to be
 298  * copied as well.
 299  */
 300 struct BlockDriverState {
 301     int64_t total_sectors; /* if we are reading a disk image, give its
 302                               size in sectors */
 303     int read_only; /* if true, the media is read only */
 304     int open_flags; /* flags used to open the file, re-used for re-open */
 305     int encrypted; /* if true, the media is encrypted */
 306     int valid_key; /* if true, a valid encryption key has been set */
 307     int sg;        /* if true, the device is a /dev/sg* */
 308     int copy_on_read; /* if true, copy read backing sectors into image
 309                          note this is a reference count */
 310
 311     BlockDriver *drv; /* NULL means no media */
 312     void *opaque;
 313
 314     void *dev;                  /* attached device model, if any */
 315     /* TODO change to DeviceState when all users are qdevified */
 316     const BlockDevOps *dev_ops;
 317     void *dev_opaque;
 318
 319     AioContext *aio_context; /* event loop used for fd handlers, timers, etc */
 320
 321     char filename[1024];
 322     char backing_file[1024]; /* if non zero, the image is a diff of
 323                                 this file image */
 324     char backing_format[16]; /* if non-zero and backing_file exists */
 325
 326     BlockDriverState *backing_hd;
 327     BlockDriverState *file;
 328
 329     NotifierList close_notifiers;
 330
 331     /* Callback before write request is processed */
 332     NotifierWithReturnList before_write_notifiers;
 333
 334     /* number of in-flight serialising requests */
 335     unsigned int serialising_in_flight;
 336
 337     /* I/O throttling */
 338     ThrottleState throttle_state;
 339     CoQueue      throttled_reqs[2];
 340     bool         io_limits_enabled;
 341
 342     /* I/O stats (display with "info blockstats"). */
 343     uint64_t nr_bytes[BDRV_MAX_IOTYPE];
 344     uint64_t nr_ops[BDRV_MAX_IOTYPE];
 345     uint64_t total_time_ns[BDRV_MAX_IOTYPE];
 346     uint64_t wr_highest_sector;
 347
 348     /* I/O Limits */
 349     BlockLimits bl;
 350
 351     /* Whether the disk can expand beyond total_sectors */
 352     int growable;
 353
 354     /* Whether produces zeros when read beyond eof */
 355     bool zero_beyond_eof;
 356
 357     /* Alignment requirement for offset/length of I/O requests */
 358     unsigned int request_alignment;
 359
 360     /* the block size for which the guest device expects atomicity */
 361     int guest_block_size;
 362
 363     /* do we need to tell the quest if we have a volatile write cache? */
 364     int enable_write_cache;
 365
 366     /* NOTE: the following infos are only hints for real hardware
 367        drivers. They are not used by the block driver */
 368     BlockdevOnError on_read_error, on_write_error;
 369     bool iostatus_enabled;
 370     BlockDeviceIoStatus iostatus;
 371
 372     /* the following member gives a name to every node on the bs graph. */
 373     char node_name[32];
 374     /* element of the list of named nodes building the graph */
 375     QTAILQ_ENTRY(BlockDriverState) node_list;
 376     /* Device name is the name associated with the "drive" the guest sees */
 377     char device_name[32];
 378     /* element of the list of "drives" the guest sees */
 379     QTAILQ_ENTRY(BlockDriverState) device_list;
 380     QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps;
 381     int refcnt;
 382
 383     QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;
 384
 385     /* operation blockers */
 386     QLIST_HEAD(, BdrvOpBlocker) op_blockers[BLOCK_OP_TYPE_MAX];
 387
 388     /* long-running background operation */
 389     BlockJob *job;
 390
 391     QDict *options;
 392     BlockdevDetectZeroesOptions detect_zeroes;
 393
 394     /* The error object in use for blocking operations on backing_hd */
 395     Error *backing_blocker;
 396 };
 397
 398 int get_tmp_filename(char *filename, int size);
 399
 400 void bdrv_set_io_limits(BlockDriverState *bs,
 401                         ThrottleConfig *cfg);
 402
 403
 404 /**
 405  * bdrv_add_before_write_notifier:
 406  *
 407  * Register a callback that is invoked before write requests are processed but
 408  * after any throttling or waiting for overlapping requests.
 409  */
 410 void bdrv_add_before_write_notifier(BlockDriverState *bs,
 411                                     NotifierWithReturn *notifier);
 412
 413 /**
 414  * bdrv_detach_aio_context:
 415  *
 416  * May be called from .bdrv_detach_aio_context() to detach children from the
 417  * current #AioContext.  This is only needed by block drivers that manage their
 418  * own children.  Both ->file and ->backing_hd are automatically handled and
 419  * block drivers should not call this function on them explicitly.
 420  */
 421 void bdrv_detach_aio_context(BlockDriverState *bs);
 422
 423 /**
 424  * bdrv_attach_aio_context:
 425  *
 426  * May be called from .bdrv_attach_aio_context() to attach children to the new
 427  * #AioContext.  This is only needed by block drivers that manage their own
 428  * children.  Both ->file and ->backing_hd are automatically handled and block
 429  * drivers should not call this function on them explicitly.
 430  */
 431 void bdrv_attach_aio_context(BlockDriverState *bs,
 432                              AioContext *new_context);
 433
 434 #ifdef _WIN32
 435 int is_windows_drive(const char *filename);
 436 #endif
 437
 438 /**
 439  * stream_start:
 440  * @bs: Block device to operate on.
 441  * @base: Block device that will become the new base, or %NULL to
 442  * flatten the whole backing file chain onto @bs.
 443  * @base_id: The file name that will be written to @bs as the new
 444  * backing file if the job completes.  Ignored if @base is %NULL.
 445  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 446  * @on_error: The action to take upon error.
 447  * @cb: Completion function for the job.
 448  * @opaque: Opaque pointer value passed to @cb.
 449  * @errp: Error object.
 450  *
 451  * Start a streaming operation on @bs.  Clusters that are unallocated
 452  * in @bs, but allocated in any image between @base and @bs (both
 453  * exclusive) will be written to @bs.  At the end of a successful
 454  * streaming job, the backing file of @bs will be changed to
 455  * @base_id in the written image and to @base in the live BlockDriverState.
 456  */
 457 void stream_start(BlockDriverState *bs, BlockDriverState *base,
 458                   const char *base_id, int64_t speed, BlockdevOnError on_error,
 459                   BlockDriverCompletionFunc *cb,
 460                   void *opaque, Error **errp);
 461
 462 /**
 463  * commit_start:
 464  * @bs: Active block device.
 465  * @top: Top block device to be committed.
 466  * @base: Block device that will be written into, and become the new top.
 467  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 468  * @on_error: The action to take upon error.
 469  * @cb: Completion function for the job.
 470  * @opaque: Opaque pointer value passed to @cb.
 471  * @backing_file_str: String to use as the backing file in @top's overlay
 472  * @errp: Error object.
 473  *
 474  */
 475 void commit_start(BlockDriverState *bs, BlockDriverState *base,
 476                  BlockDriverState *top, int64_t speed,
 477                  BlockdevOnError on_error, BlockDriverCompletionFunc *cb,
 478                  void *opaque, const char *backing_file_str, Error **errp);
 479 /**
 480  * commit_active_start:
 481  * @bs: Active block device to be committed.
 482  * @base: Block device that will be written into, and become the new top.
 483  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 484  * @on_error: The action to take upon error.
 485  * @cb: Completion function for the job.
 486  * @opaque: Opaque pointer value passed to @cb.
 487  * @errp: Error object.
 488  *
 489  */
 490 void commit_active_start(BlockDriverState *bs, BlockDriverState *base,
 491                          int64_t speed,
 492                          BlockdevOnError on_error,
 493                          BlockDriverCompletionFunc *cb,
 494                          void *opaque, Error **errp);
 495 /*
 496  * mirror_start:
 497  * @bs: Block device to operate on.
 498  * @target: Block device to write to.
 499  * @replaces: Block graph node name to replace once the mirror is done. Can
 500  *            only be used when full mirroring is selected.
 501  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 502  * @granularity: The chosen granularity for the dirty bitmap.
 503  * @buf_size: The amount of data that can be in flight at one time.
 504  * @mode: Whether to collapse all images in the chain to the target.
 505  * @on_source_error: The action to take upon error reading from the source.
 506  * @on_target_error: The action to take upon error writing to the target.
 507  * @cb: Completion function for the job.
 508  * @opaque: Opaque pointer value passed to @cb.
 509  * @errp: Error object.
 510  *
 511  * Start a mirroring operation on @bs.  Clusters that are allocated
 512  * in @bs will be written to @bs until the job is cancelled or
 513  * manually completed.  At the end of a successful mirroring job,
 514  * @bs will be switched to read from @target.
 515  */
 516 void mirror_start(BlockDriverState *bs, BlockDriverState *target,
 517                   const char *replaces,
 518                   int64_t speed, int64_t granularity, int64_t buf_size,
 519                   MirrorSyncMode mode, BlockdevOnError on_source_error,
 520                   BlockdevOnError on_target_error,
 521                   BlockDriverCompletionFunc *cb,
 522                   void *opaque, Error **errp);
 523
 524 /*
 525  * backup_start:
 526  * @bs: Block device to operate on.
 527  * @target: Block device to write to.
 528  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
 529  * @sync_mode: What parts of the disk image should be copied to the destination.
 530  * @on_source_error: The action to take upon error reading from the source.
 531  * @on_target_error: The action to take upon error writing to the target.
 532  * @cb: Completion function for the job.
 533  * @opaque: Opaque pointer value passed to @cb.
 534  *
 535  * Start a backup operation on @bs.  Clusters in @bs are written to @target
 536  * until the job is cancelled or manually completed.
 537  */
 538 void backup_start(BlockDriverState *bs, BlockDriverState *target,
 539                   int64_t speed, MirrorSyncMode sync_mode,
 540                   BlockdevOnError on_source_error,
 541                   BlockdevOnError on_target_error,
 542                   BlockDriverCompletionFunc *cb, void *opaque,
 543                   Error **errp);
 544
 545 #endif /* BLOCK_INT_H */