include/block/block-io.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_IO_H
  25 #define BLOCK_IO_H
  26
  27 #include "block/aio-wait.h"
  28 #include "block/block-common.h"
  29 #include "qemu/coroutine.h"
  30 #include "qemu/iov.h"
  31
  32 /*
  33  * I/O API functions. These functions are thread-safe, and therefore
  34  * can run in any thread as long as the thread has called
  35  * aio_context_acquire/release().
  36  *
  37  * These functions can only call functions from I/O and Common categories,
  38  * but can be invoked by GS, "I/O or GS" and I/O APIs.
  39  *
  40  * All functions in this category must use the macro
  41  * IO_CODE();
  42  * to catch when they are accidentally called by the wrong API.
  43  */
  44
  45 int co_wrapper_mixed_bdrv_rdlock
  46 bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset, int64_t bytes,
  47                    BdrvRequestFlags flags);
  48
  49 int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags);
  50
  51 int co_wrapper_mixed_bdrv_rdlock
  52 bdrv_pread(BdrvChild *child, int64_t offset, int64_t bytes, void *buf,
  53            BdrvRequestFlags flags);
  54
  55 int co_wrapper_mixed_bdrv_rdlock
  56 bdrv_pwrite(BdrvChild *child, int64_t offset,int64_t bytes,
  57             const void *buf, BdrvRequestFlags flags);
  58
  59 int co_wrapper_mixed_bdrv_rdlock
  60 bdrv_pwrite_sync(BdrvChild *child, int64_t offset, int64_t bytes,
  61                  const void *buf, BdrvRequestFlags flags);
  62
  63 int coroutine_fn GRAPH_RDLOCK
  64 bdrv_co_pwrite_sync(BdrvChild *child, int64_t offset, int64_t bytes,
  65                     const void *buf, BdrvRequestFlags flags);
  66
  67 /*
  68  * Efficiently zero a region of the disk image.  Note that this is a regular
  69  * I/O request like read or write and should have a reasonable size.  This
  70  * function is not suitable for zeroing the entire image in a single request
  71  * because it may allocate memory for the entire region.
  72  */
  73 int coroutine_fn GRAPH_RDLOCK
  74 bdrv_co_pwrite_zeroes(BdrvChild *child, int64_t offset, int64_t bytes,
  75                       BdrvRequestFlags flags);
  76
  77 int coroutine_fn GRAPH_RDLOCK
  78 bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact,
  79                  PreallocMode prealloc, BdrvRequestFlags flags, Error **errp);
  80
  81 int64_t coroutine_fn GRAPH_RDLOCK bdrv_co_nb_sectors(BlockDriverState *bs);
  82 int64_t coroutine_mixed_fn bdrv_nb_sectors(BlockDriverState *bs);
  83
  84 int64_t coroutine_fn GRAPH_RDLOCK bdrv_co_getlength(BlockDriverState *bs);
  85 int64_t co_wrapper_mixed_bdrv_rdlock bdrv_getlength(BlockDriverState *bs);
  86
  87 int64_t coroutine_fn GRAPH_RDLOCK
  88 bdrv_co_get_allocated_file_size(BlockDriverState *bs);
  89
  90 int64_t co_wrapper_bdrv_rdlock
  91 bdrv_get_allocated_file_size(BlockDriverState *bs);
  92
  93 BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts,
  94                                BlockDriverState *in_bs, Error **errp);
  95
  96 int coroutine_fn GRAPH_RDLOCK
  97 bdrv_co_delete_file(BlockDriverState *bs, Error **errp);
  98
  99 void coroutine_fn GRAPH_RDLOCK
 100 bdrv_co_delete_file_noerr(BlockDriverState *bs);
 101
 102
 103 /* async block I/O */
 104 void bdrv_aio_cancel_async(BlockAIOCB *acb);
 105
 106 /* sg packet commands */
 107 int coroutine_fn GRAPH_RDLOCK
 108 bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf);
 109
 110 /* Ensure contents are flushed to disk.  */
 111 int coroutine_fn GRAPH_RDLOCK bdrv_co_flush(BlockDriverState *bs);
 112
 113 int coroutine_fn GRAPH_RDLOCK bdrv_co_pdiscard(BdrvChild *child, int64_t offset,
 114                                                int64_t bytes);
 115
 116 /* Report zone information of zone block device. */
 117 int coroutine_fn GRAPH_RDLOCK bdrv_co_zone_report(BlockDriverState *bs,
 118                                                   int64_t offset,
 119                                                   unsigned int *nr_zones,
 120                                                   BlockZoneDescriptor *zones);
 121 int coroutine_fn GRAPH_RDLOCK bdrv_co_zone_mgmt(BlockDriverState *bs,
 122                                                 BlockZoneOp op,
 123                                                 int64_t offset, int64_t len);
 124 int coroutine_fn GRAPH_RDLOCK bdrv_co_zone_append(BlockDriverState *bs,
 125                                                   int64_t *offset,
 126                                                   QEMUIOVector *qiov,
 127                                                   BdrvRequestFlags flags);
 128
 129 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs);
 130
 131 int coroutine_fn GRAPH_RDLOCK
 132 bdrv_co_block_status(BlockDriverState *bs, int64_t offset, int64_t bytes,
 133                      int64_t *pnum, int64_t *map, BlockDriverState **file);
 134 int co_wrapper_mixed_bdrv_rdlock
 135 bdrv_block_status(BlockDriverState *bs, int64_t offset, int64_t bytes,
 136                   int64_t *pnum, int64_t *map, BlockDriverState **file);
 137
 138 int coroutine_fn GRAPH_RDLOCK
 139 bdrv_co_block_status_above(BlockDriverState *bs, BlockDriverState *base,
 140                            int64_t offset, int64_t bytes, int64_t *pnum,
 141                            int64_t *map, BlockDriverState **file);
 142 int co_wrapper_mixed_bdrv_rdlock
 143 bdrv_block_status_above(BlockDriverState *bs, BlockDriverState *base,
 144                         int64_t offset, int64_t bytes, int64_t *pnum,
 145                         int64_t *map, BlockDriverState **file);
 146
 147 int coroutine_fn GRAPH_RDLOCK
 148 bdrv_co_is_allocated(BlockDriverState *bs, int64_t offset, int64_t bytes,
 149                      int64_t *pnum);
 150 int co_wrapper_mixed_bdrv_rdlock
 151 bdrv_is_allocated(BlockDriverState *bs, int64_t offset,
 152                   int64_t bytes, int64_t *pnum);
 153
 154 int coroutine_fn GRAPH_RDLOCK
 155 bdrv_co_is_allocated_above(BlockDriverState *top, BlockDriverState *base,
 156                            bool include_base, int64_t offset, int64_t bytes,
 157                            int64_t *pnum);
 158 int co_wrapper_mixed_bdrv_rdlock
 159 bdrv_is_allocated_above(BlockDriverState *bs, BlockDriverState *base,
 160                         bool include_base, int64_t offset,
 161                         int64_t bytes, int64_t *pnum);
 162
 163 int coroutine_fn GRAPH_RDLOCK
 164 bdrv_co_is_zero_fast(BlockDriverState *bs, int64_t offset, int64_t bytes);
 165
 166 int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
 167                               Error **errp);
 168 bool bdrv_is_read_only(BlockDriverState *bs);
 169 bool bdrv_is_writable(BlockDriverState *bs);
 170 bool bdrv_is_sg(BlockDriverState *bs);
 171 int bdrv_get_flags(BlockDriverState *bs);
 172
 173 bool coroutine_fn GRAPH_RDLOCK bdrv_co_is_inserted(BlockDriverState *bs);
 174 bool co_wrapper_bdrv_rdlock bdrv_is_inserted(BlockDriverState *bs);
 175
 176 void coroutine_fn GRAPH_RDLOCK
 177 bdrv_co_lock_medium(BlockDriverState *bs, bool locked);
 178
 179 void coroutine_fn GRAPH_RDLOCK
 180 bdrv_co_eject(BlockDriverState *bs, bool eject_flag);
 181
 182 const char *bdrv_get_format_name(BlockDriverState *bs);
 183
 184 bool bdrv_supports_compressed_writes(BlockDriverState *bs);
 185 const char *bdrv_get_node_name(const BlockDriverState *bs);
 186
 187 const char * GRAPH_RDLOCK
 188 bdrv_get_device_name(const BlockDriverState *bs);
 189
 190 const char * GRAPH_RDLOCK
 191 bdrv_get_device_or_node_name(const BlockDriverState *bs);
 192
 193 int coroutine_fn GRAPH_RDLOCK
 194 bdrv_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi);
 195
 196 int co_wrapper_mixed_bdrv_rdlock
 197 bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi);
 198
 199 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs,
 200                                           Error **errp);
 201 BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs);
 202 void bdrv_round_to_subclusters(BlockDriverState *bs,
 203                                int64_t offset, int64_t bytes,
 204                                int64_t *cluster_offset,
 205                                int64_t *cluster_bytes);
 206
 207 void bdrv_get_backing_filename(BlockDriverState *bs,
 208                                char *filename, int filename_size);
 209
 210 int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
 211                       int64_t pos, int size);
 212
 213 int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
 214                       int64_t pos, int size);
 215
 216 /*
 217  * Returns the alignment in bytes that is required so that no bounce buffer
 218  * is required throughout the stack
 219  */
 220 size_t bdrv_min_mem_align(BlockDriverState *bs);
 221 /* Returns optimal alignment in bytes for bounce buffer */
 222 size_t bdrv_opt_mem_align(BlockDriverState *bs);
 223 void *qemu_blockalign(BlockDriverState *bs, size_t size);
 224 void *qemu_blockalign0(BlockDriverState *bs, size_t size);
 225 void *qemu_try_blockalign(BlockDriverState *bs, size_t size);
 226 void *qemu_try_blockalign0(BlockDriverState *bs, size_t size);
 227
 228 void bdrv_enable_copy_on_read(BlockDriverState *bs);
 229 void bdrv_disable_copy_on_read(BlockDriverState *bs);
 230
 231 void coroutine_fn GRAPH_RDLOCK
 232 bdrv_co_debug_event(BlockDriverState *bs, BlkdebugEvent event);
 233
 234 void co_wrapper_mixed_bdrv_rdlock
 235 bdrv_debug_event(BlockDriverState *bs, BlkdebugEvent event);
 236
 237 #define BLKDBG_CO_EVENT(child, evt) \
 238     do { \
 239         if (child) { \
 240             bdrv_co_debug_event(child->bs, evt); \
 241         } \
 242     } while (0)
 243
 244 #define BLKDBG_EVENT(child, evt) \
 245     do { \
 246         if (child) { \
 247             bdrv_debug_event(child->bs, evt); \
 248         } \
 249     } while (0)
 250
 251 /**
 252  * bdrv_get_aio_context:
 253  *
 254  * Returns: the currently bound #AioContext
 255  */
 256 AioContext *bdrv_get_aio_context(BlockDriverState *bs);
 257
 258 AioContext *bdrv_child_get_parent_aio_context(BdrvChild *c);
 259
 260 /**
 261  * Move the current coroutine to the AioContext of @bs and return the old
 262  * AioContext of the coroutine. Increase bs->in_flight so that draining @bs
 263  * will wait for the operation to proceed until the corresponding
 264  * bdrv_co_leave().
 265  *
 266  * Consequently, you can't call drain inside a bdrv_co_enter/leave() section as
 267  * this will deadlock.
 268  */
 269 AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs);
 270
 271 /**
 272  * Ends a section started by bdrv_co_enter(). Move the current coroutine back
 273  * to old_ctx and decrease bs->in_flight again.
 274  */
 275 void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx);
 276
 277 AioContext *child_of_bds_get_parent_aio_context(BdrvChild *c);
 278
 279 bool coroutine_fn GRAPH_RDLOCK
 280 bdrv_co_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name,
 281                                    uint32_t granularity, Error **errp);
 282 bool co_wrapper_bdrv_rdlock
 283 bdrv_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name,
 284                                 uint32_t granularity, Error **errp);
 285
 286 /**
 287  *
 288  * bdrv_co_copy_range:
 289  *
 290  * Do offloaded copy between two children. If the operation is not implemented
 291  * by the driver, or if the backend storage doesn't support it, a negative
 292  * error code will be returned.
 293  *
 294  * Note: block layer doesn't emulate or fallback to a bounce buffer approach
 295  * because usually the caller shouldn't attempt offloaded copy any more (e.g.
 296  * calling copy_file_range(2)) after the first error, thus it should fall back
 297  * to a read+write path in the caller level.
 298  *
 299  * @src: Source child to copy data from
 300  * @src_offset: offset in @src image to read data
 301  * @dst: Destination child to copy data to
 302  * @dst_offset: offset in @dst image to write data
 303  * @bytes: number of bytes to copy
 304  * @flags: request flags. Supported flags:
 305  *         BDRV_REQ_ZERO_WRITE - treat the @src range as zero data and do zero
 306  *                               write on @dst as if bdrv_co_pwrite_zeroes is
 307  *                               called. Used to simplify caller code, or
 308  *                               during BlockDriver.bdrv_co_copy_range_from()
 309  *                               recursion.
 310  *         BDRV_REQ_NO_SERIALISING - do not serialize with other overlapping
 311  *                                   requests currently in flight.
 312  *
 313  * Returns: 0 if succeeded; negative error code if failed.
 314  **/
 315 int coroutine_fn GRAPH_RDLOCK
 316 bdrv_co_copy_range(BdrvChild *src, int64_t src_offset,
 317                    BdrvChild *dst, int64_t dst_offset,
 318                    int64_t bytes, BdrvRequestFlags read_flags,
 319                    BdrvRequestFlags write_flags);
 320
 321 /*
 322  * "I/O or GS" API functions. These functions can run without
 323  * the BQL, but only in one specific iothread/main loop.
 324  *
 325  * More specifically, these functions use BDRV_POLL_WHILE(bs), which
 326  * requires the caller to be either in the main thread and hold
 327  * the BlockdriverState (bs) AioContext lock, or directly in the
 328  * home thread that runs the bs AioContext. Calling them from
 329  * another thread in another AioContext would cause deadlocks.
 330  *
 331  * Therefore, these functions are not proper I/O, because they
 332  * can't run in *any* iothreads, but only in a specific one.
 333  *
 334  * These functions can call any function from I/O, Common and this
 335  * categories, but must be invoked only by other "I/O or GS" and GS APIs.
 336  *
 337  * All functions in this category must use the macro
 338  * IO_OR_GS_CODE();
 339  * to catch when they are accidentally called by the wrong API.
 340  */
 341
 342 #define BDRV_POLL_WHILE(bs, cond) ({                       \
 343     BlockDriverState *bs_ = (bs);                          \
 344     IO_OR_GS_CODE();                                       \
 345     AIO_WAIT_WHILE(bdrv_get_aio_context(bs_),              \
 346                    cond); })
 347
 348 void bdrv_drain(BlockDriverState *bs);
 349
 350 int co_wrapper_mixed_bdrv_rdlock
 351 bdrv_truncate(BdrvChild *child, int64_t offset, bool exact,
 352               PreallocMode prealloc, BdrvRequestFlags flags, Error **errp);
 353
 354 int co_wrapper_mixed_bdrv_rdlock
 355 bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode fix);
 356
 357 /* Invalidate any cached metadata used by image formats */
 358 int co_wrapper_mixed_bdrv_rdlock
 359 bdrv_invalidate_cache(BlockDriverState *bs, Error **errp);
 360
 361 int co_wrapper_mixed_bdrv_rdlock bdrv_flush(BlockDriverState *bs);
 362
 363 int co_wrapper_mixed_bdrv_rdlock
 364 bdrv_pdiscard(BdrvChild *child, int64_t offset, int64_t bytes);
 365
 366 int co_wrapper_mixed_bdrv_rdlock
 367 bdrv_readv_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos);
 368
 369 int co_wrapper_mixed_bdrv_rdlock
 370 bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos);
 371
 372 /**
 373  * bdrv_parent_drained_begin_single:
 374  *
 375  * Begin a quiesced section for the parent of @c.
 376  */
 377 void GRAPH_RDLOCK bdrv_parent_drained_begin_single(BdrvChild *c);
 378
 379 /**
 380  * bdrv_parent_drained_poll_single:
 381  *
 382  * Returns true if there is any pending activity to cease before @c can be
 383  * called quiesced, false otherwise.
 384  */
 385 bool GRAPH_RDLOCK bdrv_parent_drained_poll_single(BdrvChild *c);
 386
 387 /**
 388  * bdrv_parent_drained_end_single:
 389  *
 390  * End a quiesced section for the parent of @c.
 391  */
 392 void GRAPH_RDLOCK bdrv_parent_drained_end_single(BdrvChild *c);
 393
 394 /**
 395  * bdrv_drain_poll:
 396  *
 397  * Poll for pending requests in @bs and its parents (except for @ignore_parent).
 398  *
 399  * If @ignore_bds_parents is true, parents that are BlockDriverStates must
 400  * ignore the drain request because they will be drained separately (used for
 401  * drain_all).
 402  *
 403  * This is part of bdrv_drained_begin.
 404  */
 405 bool GRAPH_RDLOCK
 406 bdrv_drain_poll(BlockDriverState *bs, BdrvChild *ignore_parent,
 407                 bool ignore_bds_parents);
 408
 409 /**
 410  * bdrv_drained_begin:
 411  *
 412  * Begin a quiesced section for exclusive access to the BDS, by disabling
 413  * external request sources including NBD server, block jobs, and device model.
 414  *
 415  * This function can only be invoked by the main loop or a coroutine
 416  * (regardless of the AioContext where it is running).
 417  * If the coroutine is running in an Iothread AioContext, this function will
 418  * just schedule a BH to run in the main loop.
 419  * However, it cannot be directly called by an Iothread.
 420  *
 421  * This function can be recursive.
 422  */
 423 void bdrv_drained_begin(BlockDriverState *bs);
 424
 425 /**
 426  * bdrv_do_drained_begin_quiesce:
 427  *
 428  * Quiesces a BDS like bdrv_drained_begin(), but does not wait for already
 429  * running requests to complete.
 430  */
 431 void bdrv_do_drained_begin_quiesce(BlockDriverState *bs, BdrvChild *parent);
 432
 433 /**
 434  * bdrv_drained_end:
 435  *
 436  * End a quiescent section started by bdrv_drained_begin().
 437  *
 438  * This function can only be invoked by the main loop or a coroutine
 439  * (regardless of the AioContext where it is running).
 440  * If the coroutine is running in an Iothread AioContext, this function will
 441  * just schedule a BH to run in the main loop.
 442  * However, it cannot be directly called by an Iothread.
 443  */
 444 void bdrv_drained_end(BlockDriverState *bs);
 445
 446 #endif /* BLOCK_IO_H */