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