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 */ 369