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); 273 274 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