block-io.h (15603B)
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 * bdrv_drained_end_no_poll: 242 * 243 * Same as bdrv_drained_end(), but do not poll for the subgraph to 244 * actually become unquiesced. Therefore, no graph changes will occur 245 * with this function. 246 * 247 * *drained_end_counter is incremented for every background operation 248 * that is scheduled, and will be decremented for every operation once 249 * it settles. The caller must poll until it reaches 0. The counter 250 * should be accessed using atomic operations only. 251 */ 252 void bdrv_drained_end_no_poll(BlockDriverState *bs, int *drained_end_counter); 253 254 255 /* 256 * "I/O or GS" API functions. These functions can run without 257 * the BQL, but only in one specific iothread/main loop. 258 * 259 * More specifically, these functions use BDRV_POLL_WHILE(bs), which 260 * requires the caller to be either in the main thread and hold 261 * the BlockdriverState (bs) AioContext lock, or directly in the 262 * home thread that runs the bs AioContext. Calling them from 263 * another thread in another AioContext would cause deadlocks. 264 * 265 * Therefore, these functions are not proper I/O, because they 266 * can't run in *any* iothreads, but only in a specific one. 267 * 268 * These functions can call any function from I/O, Common and this 269 * categories, but must be invoked only by other "I/O or GS" and GS APIs. 270 * 271 * All functions in this category must use the macro 272 * IO_OR_GS_CODE(); 273 * to catch when they are accidentally called by the wrong API. 274 */ 275 276 #define BDRV_POLL_WHILE(bs, cond) ({ \ 277 BlockDriverState *bs_ = (bs); \ 278 IO_OR_GS_CODE(); \ 279 AIO_WAIT_WHILE(bdrv_get_aio_context(bs_), \ 280 cond); }) 281 282 void bdrv_drain(BlockDriverState *bs); 283 284 int generated_co_wrapper 285 bdrv_truncate(BdrvChild *child, int64_t offset, bool exact, 286 PreallocMode prealloc, BdrvRequestFlags flags, Error **errp); 287 288 int generated_co_wrapper bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, 289 BdrvCheckMode fix); 290 291 /* Invalidate any cached metadata used by image formats */ 292 int generated_co_wrapper bdrv_invalidate_cache(BlockDriverState *bs, 293 Error **errp); 294 int generated_co_wrapper bdrv_flush(BlockDriverState *bs); 295 int generated_co_wrapper bdrv_pdiscard(BdrvChild *child, int64_t offset, 296 int64_t bytes); 297 int generated_co_wrapper 298 bdrv_readv_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos); 299 int generated_co_wrapper 300 bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos); 301 302 /** 303 * bdrv_parent_drained_begin_single: 304 * 305 * Begin a quiesced section for the parent of @c. If @poll is true, wait for 306 * any pending activity to cease. 307 */ 308 void bdrv_parent_drained_begin_single(BdrvChild *c, bool poll); 309 310 /** 311 * bdrv_parent_drained_end_single: 312 * 313 * End a quiesced section for the parent of @c. 314 * 315 * This polls @bs's AioContext until all scheduled sub-drained_ends 316 * have settled, which may result in graph changes. 317 */ 318 void bdrv_parent_drained_end_single(BdrvChild *c); 319 320 /** 321 * bdrv_drain_poll: 322 * 323 * Poll for pending requests in @bs, its parents (except for @ignore_parent), 324 * and if @recursive is true its children as well (used for subtree drain). 325 * 326 * If @ignore_bds_parents is true, parents that are BlockDriverStates must 327 * ignore the drain request because they will be drained separately (used for 328 * drain_all). 329 * 330 * This is part of bdrv_drained_begin. 331 */ 332 bool bdrv_drain_poll(BlockDriverState *bs, bool recursive, 333 BdrvChild *ignore_parent, bool ignore_bds_parents); 334 335 /** 336 * bdrv_drained_begin: 337 * 338 * Begin a quiesced section for exclusive access to the BDS, by disabling 339 * external request sources including NBD server, block jobs, and device model. 340 * 341 * This function can be recursive. 342 */ 343 void bdrv_drained_begin(BlockDriverState *bs); 344 345 /** 346 * bdrv_do_drained_begin_quiesce: 347 * 348 * Quiesces a BDS like bdrv_drained_begin(), but does not wait for already 349 * running requests to complete. 350 */ 351 void bdrv_do_drained_begin_quiesce(BlockDriverState *bs, 352 BdrvChild *parent, bool ignore_bds_parents); 353 354 /** 355 * Like bdrv_drained_begin, but recursively begins a quiesced section for 356 * exclusive access to all child nodes as well. 357 */ 358 void bdrv_subtree_drained_begin(BlockDriverState *bs); 359 360 /** 361 * bdrv_drained_end: 362 * 363 * End a quiescent section started by bdrv_drained_begin(). 364 * 365 * This polls @bs's AioContext until all scheduled sub-drained_ends 366 * have settled. On one hand, that may result in graph changes. On 367 * the other, this requires that the caller either runs in the main 368 * loop; or that all involved nodes (@bs and all of its parents) are 369 * in the caller's AioContext. 370 */ 371 void bdrv_drained_end(BlockDriverState *bs); 372 373 /** 374 * End a quiescent section started by bdrv_subtree_drained_begin(). 375 */ 376 void bdrv_subtree_drained_end(BlockDriverState *bs); 377 378 #endif /* BLOCK_IO_H */