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