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-common.h"
  28
  29 /*
  30  * I/O API functions. These functions are thread-safe, and therefore
  31  * can run in any thread as long as the thread has called
  32  * aio_context_acquire/release().
  33  *
  34  * These functions can only call functions from I/O and Common categories,
  35  * but can be invoked by GS, "I/O or GS" and I/O APIs.
  36  *
  37  * All functions in this category must use the macro
  38  * IO_CODE();
  39  * to catch when they are accidentally called by the wrong API.
  40  */
  41
  42 int bdrv_pwrite_zeroes(BdrvChild *child, int64_t offset,
  43                        int64_t bytes, BdrvRequestFlags flags);
  44 int bdrv_make_zero(BdrvChild *child, BdrvRequestFlags flags);
  45 int bdrv_pread(BdrvChild *child, int64_t offset, void *buf, int64_t bytes);
  46 int bdrv_pwrite(BdrvChild *child, int64_t offset, const void *buf,
  47                 int64_t bytes);
  48 int bdrv_pwrite_sync(BdrvChild *child, int64_t offset,
  49                      const void *buf, int64_t bytes);
  50 /*
  51  * Efficiently zero a region of the disk image.  Note that this is a regular
  52  * I/O request like read or write and should have a reasonable size.  This
  53  * function is not suitable for zeroing the entire image in a single request
  54  * because it may allocate memory for the entire region.
  55  */
  56 int coroutine_fn bdrv_co_pwrite_zeroes(BdrvChild *child, int64_t offset,
  57                                        int64_t bytes, BdrvRequestFlags flags);
  58
  59 int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact,
  60                                   PreallocMode prealloc, BdrvRequestFlags flags,
  61                                   Error **errp);
  62
  63 int64_t bdrv_nb_sectors(BlockDriverState *bs);
  64 int64_t bdrv_getlength(BlockDriverState *bs);
  65 int64_t bdrv_get_allocated_file_size(BlockDriverState *bs);
  66 BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts,
  67                                BlockDriverState *in_bs, Error **errp);
  68 void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr);
  69 int coroutine_fn bdrv_co_delete_file(BlockDriverState *bs, Error **errp);
  70 void coroutine_fn bdrv_co_delete_file_noerr(BlockDriverState *bs);
  71
  72
  73 /* async block I/O */
  74 void bdrv_aio_cancel(BlockAIOCB *acb);
  75 void bdrv_aio_cancel_async(BlockAIOCB *acb);
  76
  77 /* sg packet commands */
  78 int bdrv_co_ioctl(BlockDriverState *bs, int req, void *buf);
  79
  80 /* Ensure contents are flushed to disk.  */
  81 int coroutine_fn bdrv_co_flush(BlockDriverState *bs);
  82
  83 int bdrv_co_pdiscard(BdrvChild *child, int64_t offset, int64_t bytes);
  84 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs);
  85 int bdrv_block_status(BlockDriverState *bs, int64_t offset,
  86                       int64_t bytes, int64_t *pnum, int64_t *map,
  87                       BlockDriverState **file);
  88 int bdrv_block_status_above(BlockDriverState *bs, BlockDriverState *base,
  89                             int64_t offset, int64_t bytes, int64_t *pnum,
  90                             int64_t *map, BlockDriverState **file);
  91 int bdrv_is_allocated(BlockDriverState *bs, int64_t offset, int64_t bytes,
  92                       int64_t *pnum);
  93 int bdrv_is_allocated_above(BlockDriverState *top, BlockDriverState *base,
  94                             bool include_base, int64_t offset, int64_t bytes,
  95                             int64_t *pnum);
  96 int coroutine_fn bdrv_co_is_zero_fast(BlockDriverState *bs, int64_t offset,
  97                                       int64_t bytes);
  98
  99 int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
 100                            bool ignore_allow_rdw, Error **errp);
 101 int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
 102                               Error **errp);
 103 bool bdrv_is_read_only(BlockDriverState *bs);
 104 bool bdrv_is_writable(BlockDriverState *bs);
 105 bool bdrv_is_sg(BlockDriverState *bs);
 106 int bdrv_get_flags(BlockDriverState *bs);
 107 bool bdrv_is_inserted(BlockDriverState *bs);
 108 void bdrv_lock_medium(BlockDriverState *bs, bool locked);
 109 void bdrv_eject(BlockDriverState *bs, bool eject_flag);
 110 const char *bdrv_get_format_name(BlockDriverState *bs);
 111
 112 bool bdrv_supports_compressed_writes(BlockDriverState *bs);
 113 const char *bdrv_get_node_name(const BlockDriverState *bs);
 114 const char *bdrv_get_device_name(const BlockDriverState *bs);
 115 const char *bdrv_get_device_or_node_name(const BlockDriverState *bs);
 116 int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi);
 117 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs,
 118                                           Error **errp);
 119 BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs);
 120 void bdrv_round_to_clusters(BlockDriverState *bs,
 121                             int64_t offset, int64_t bytes,
 122                             int64_t *cluster_offset,
 123                             int64_t *cluster_bytes);
 124
 125 void bdrv_get_backing_filename(BlockDriverState *bs,
 126                                char *filename, int filename_size);
 127
 128 int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
 129                       int64_t pos, int size);
 130
 131 int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
 132                       int64_t pos, int size);
 133
 134 /*
 135  * Returns the alignment in bytes that is required so that no bounce buffer
 136  * is required throughout the stack
 137  */
 138 size_t bdrv_min_mem_align(BlockDriverState *bs);
 139 /* Returns optimal alignment in bytes for bounce buffer */
 140 size_t bdrv_opt_mem_align(BlockDriverState *bs);
 141 void *qemu_blockalign(BlockDriverState *bs, size_t size);
 142 void *qemu_blockalign0(BlockDriverState *bs, size_t size);
 143 void *qemu_try_blockalign(BlockDriverState *bs, size_t size);
 144 void *qemu_try_blockalign0(BlockDriverState *bs, size_t size);
 145 bool bdrv_qiov_is_aligned(BlockDriverState *bs, QEMUIOVector *qiov);
 146
 147 void bdrv_enable_copy_on_read(BlockDriverState *bs);
 148 void bdrv_disable_copy_on_read(BlockDriverState *bs);
 149
 150 void bdrv_debug_event(BlockDriverState *bs, BlkdebugEvent event);
 151
 152 #define BLKDBG_EVENT(child, evt) \
 153     do { \
 154         if (child) { \
 155             bdrv_debug_event(child->bs, evt); \
 156         } \
 157     } while (0)
 158
 159 /**
 160  * bdrv_get_aio_context:
 161  *
 162  * Returns: the currently bound #AioContext
 163  */
 164 AioContext *bdrv_get_aio_context(BlockDriverState *bs);
 165
 166 /**
 167  * Move the current coroutine to the AioContext of @bs and return the old
 168  * AioContext of the coroutine. Increase bs->in_flight so that draining @bs
 169  * will wait for the operation to proceed until the corresponding
 170  * bdrv_co_leave().
 171  *
 172  * Consequently, you can't call drain inside a bdrv_co_enter/leave() section as
 173  * this will deadlock.
 174  */
 175 AioContext *coroutine_fn bdrv_co_enter(BlockDriverState *bs);
 176
 177 /**
 178  * Ends a section started by bdrv_co_enter(). Move the current coroutine back
 179  * to old_ctx and decrease bs->in_flight again.
 180  */
 181 void coroutine_fn bdrv_co_leave(BlockDriverState *bs, AioContext *old_ctx);
 182
 183 /**
 184  * Transfer control to @co in the aio context of @bs
 185  */
 186 void bdrv_coroutine_enter(BlockDriverState *bs, Coroutine *co);
 187
 188 AioContext *child_of_bds_get_parent_aio_context(BdrvChild *c);
 189
 190 void bdrv_io_plug(BlockDriverState *bs);
 191 void bdrv_io_unplug(BlockDriverState *bs);
 192
 193 bool bdrv_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name,
 194                                      uint32_t granularity, Error **errp);
 195
 196 /**
 197  *
 198  * bdrv_co_copy_range:
 199  *
 200  * Do offloaded copy between two children. If the operation is not implemented
 201  * by the driver, or if the backend storage doesn't support it, a negative
 202  * error code will be returned.
 203  *
 204  * Note: block layer doesn't emulate or fallback to a bounce buffer approach
 205  * because usually the caller shouldn't attempt offloaded copy any more (e.g.
 206  * calling copy_file_range(2)) after the first error, thus it should fall back
 207  * to a read+write path in the caller level.
 208  *
 209  * @src: Source child to copy data from
 210  * @src_offset: offset in @src image to read data
 211  * @dst: Destination child to copy data to
 212  * @dst_offset: offset in @dst image to write data
 213  * @bytes: number of bytes to copy
 214  * @flags: request flags. Supported flags:
 215  *         BDRV_REQ_ZERO_WRITE - treat the @src range as zero data and do zero
 216  *                               write on @dst as if bdrv_co_pwrite_zeroes is
 217  *                               called. Used to simplify caller code, or
 218  *                               during BlockDriver.bdrv_co_copy_range_from()
 219  *                               recursion.
 220  *         BDRV_REQ_NO_SERIALISING - do not serialize with other overlapping
 221  *                                   requests currently in flight.
 222  *
 223  * Returns: 0 if succeeded; negative error code if failed.
 224  **/
 225 int coroutine_fn bdrv_co_copy_range(BdrvChild *src, int64_t src_offset,
 226                                     BdrvChild *dst, int64_t dst_offset,
 227                                     int64_t bytes, BdrvRequestFlags read_flags,
 228                                     BdrvRequestFlags write_flags);
 229
 230 /**
 231  * bdrv_drained_end_no_poll:
 232  *
 233  * Same as bdrv_drained_end(), but do not poll for the subgraph to
 234  * actually become unquiesced.  Therefore, no graph changes will occur
 235  * with this function.
 236  *
 237  * *drained_end_counter is incremented for every background operation
 238  * that is scheduled, and will be decremented for every operation once
 239  * it settles.  The caller must poll until it reaches 0.  The counter
 240  * should be accessed using atomic operations only.
 241  */
 242 void bdrv_drained_end_no_poll(BlockDriverState *bs, int *drained_end_counter);
 243
 244
 245 /*
 246  * "I/O or GS" API functions. These functions can run without
 247  * the BQL, but only in one specific iothread/main loop.
 248  *
 249  * More specifically, these functions use BDRV_POLL_WHILE(bs), which
 250  * requires the caller to be either in the main thread and hold
 251  * the BlockdriverState (bs) AioContext lock, or directly in the
 252  * home thread that runs the bs AioContext. Calling them from
 253  * another thread in another AioContext would cause deadlocks.
 254  *
 255  * Therefore, these functions are not proper I/O, because they
 256  * can't run in *any* iothreads, but only in a specific one.
 257  *
 258  * These functions can call any function from I/O, Common and this
 259  * categories, but must be invoked only by other "I/O or GS" and GS APIs.
 260  *
 261  * All functions in this category must use the macro
 262  * IO_OR_GS_CODE();
 263  * to catch when they are accidentally called by the wrong API.
 264  */
 265
 266 #define BDRV_POLL_WHILE(bs, cond) ({                       \
 267     BlockDriverState *bs_ = (bs);                          \
 268     IO_OR_GS_CODE();                                       \
 269     AIO_WAIT_WHILE(bdrv_get_aio_context(bs_),              \
 270                    cond); })
 271
 272 void bdrv_drain(BlockDriverState *bs);
 273 void coroutine_fn bdrv_co_drain(BlockDriverState *bs);
 274
 275 int generated_co_wrapper
 276 bdrv_truncate(BdrvChild *child, int64_t offset, bool exact,
 277               PreallocMode prealloc, BdrvRequestFlags flags, Error **errp);
 278
 279 int generated_co_wrapper bdrv_check(BlockDriverState *bs, BdrvCheckResult *res,
 280                                     BdrvCheckMode fix);
 281
 282 /* Invalidate any cached metadata used by image formats */
 283 int generated_co_wrapper bdrv_invalidate_cache(BlockDriverState *bs,
 284                                                Error **errp);
 285 int generated_co_wrapper bdrv_flush(BlockDriverState *bs);
 286 int generated_co_wrapper bdrv_pdiscard(BdrvChild *child, int64_t offset,
 287                                        int64_t bytes);
 288 int generated_co_wrapper
 289 bdrv_readv_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos);
 290 int generated_co_wrapper
 291 bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos);
 292
 293 /**
 294  * bdrv_parent_drained_begin_single:
 295  *
 296  * Begin a quiesced section for the parent of @c. If @poll is true, wait for
 297  * any pending activity to cease.
 298  */
 299 void bdrv_parent_drained_begin_single(BdrvChild *c, bool poll);
 300
 301 /**
 302  * bdrv_parent_drained_end_single:
 303  *
 304  * End a quiesced section for the parent of @c.
 305  *
 306  * This polls @bs's AioContext until all scheduled sub-drained_ends
 307  * have settled, which may result in graph changes.
 308  */
 309 void bdrv_parent_drained_end_single(BdrvChild *c);
 310
 311 /**
 312  * bdrv_drain_poll:
 313  *
 314  * Poll for pending requests in @bs, its parents (except for @ignore_parent),
 315  * and if @recursive is true its children as well (used for subtree drain).
 316  *
 317  * If @ignore_bds_parents is true, parents that are BlockDriverStates must
 318  * ignore the drain request because they will be drained separately (used for
 319  * drain_all).
 320  *
 321  * This is part of bdrv_drained_begin.
 322  */
 323 bool bdrv_drain_poll(BlockDriverState *bs, bool recursive,
 324                      BdrvChild *ignore_parent, bool ignore_bds_parents);
 325
 326 /**
 327  * bdrv_drained_begin:
 328  *
 329  * Begin a quiesced section for exclusive access to the BDS, by disabling
 330  * external request sources including NBD server, block jobs, and device model.
 331  *
 332  * This function can be recursive.
 333  */
 334 void bdrv_drained_begin(BlockDriverState *bs);
 335
 336 /**
 337  * bdrv_do_drained_begin_quiesce:
 338  *
 339  * Quiesces a BDS like bdrv_drained_begin(), but does not wait for already
 340  * running requests to complete.
 341  */
 342 void bdrv_do_drained_begin_quiesce(BlockDriverState *bs,
 343                                    BdrvChild *parent, bool ignore_bds_parents);
 344
 345 /**
 346  * Like bdrv_drained_begin, but recursively begins a quiesced section for
 347  * exclusive access to all child nodes as well.
 348  */
 349 void bdrv_subtree_drained_begin(BlockDriverState *bs);
 350
 351 /**
 352  * bdrv_drained_end:
 353  *
 354  * End a quiescent section started by bdrv_drained_begin().
 355  *
 356  * This polls @bs's AioContext until all scheduled sub-drained_ends
 357  * have settled.  On one hand, that may result in graph changes.  On
 358  * the other, this requires that the caller either runs in the main
 359  * loop; or that all involved nodes (@bs and all of its parents) are
 360  * in the caller's AioContext.
 361  */
 362 void bdrv_drained_end(BlockDriverState *bs);
 363
 364 /**
 365  * End a quiescent section started by bdrv_subtree_drained_begin().
 366  */
 367 void bdrv_subtree_drained_end(BlockDriverState *bs);
 368
 369 #endif /* BLOCK_IO_H */