| 1 | /* |
| 2 | * copy-before-write filter driver |
| 3 | * |
| 4 | * The driver performs Copy-Before-Write (CBW) operation: it is injected above |
| 5 | * some node, and before each write it copies _old_ data to the target node. |
| 6 | * |
| 7 | * Copyright (c) 2018-2021 Virtuozzo International GmbH. |
| 8 | * |
| 9 | * Author: |
| 10 | * Sementsov-Ogievskiy Vladimir <vsementsov@virtuozzo.com> |
| 11 | * |
| 12 | * This program is free software; you can redistribute it and/or modify |
| 13 | * it under the terms of the GNU General Public License as published by |
| 14 | * the Free Software Foundation; either version 2 of the License, or |
| 15 | * (at your option) any later version. |
| 16 | * |
| 17 | * This program is distributed in the hope that it will be useful, |
| 18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 20 | * GNU General Public License for more details. |
| 21 | * |
| 22 | * You should have received a copy of the GNU General Public License |
| 23 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 24 | */ |
| 25 | |
| 26 | #include "qemu/osdep.h" |
| 27 | #include "qobject/qjson.h" |
| 28 | |
| 29 | #include "system/block-backend.h" |
| 30 | #include "qemu/cutils.h" |
| 31 | #include "qapi/error.h" |
| 32 | #include "block/block_int.h" |
| 33 | #include "block/qdict.h" |
| 34 | #include "block/block-copy.h" |
| 35 | #include "block/dirty-bitmap.h" |
| 36 | |
| 37 | #include "block/copy-before-write.h" |
| 38 | #include "block/reqlist.h" |
| 39 | |
| 40 | #include "qapi/qapi-visit-block-core.h" |
| 41 | |
| 42 | typedef struct BDRVCopyBeforeWriteState { |
| 43 | BlockCopyState *bcs; |
| 44 | BdrvChild *target; |
| 45 | OnCbwError on_cbw_error; |
| 46 | uint64_t cbw_timeout_ns; |
| 47 | bool discard_source; |
| 48 | |
| 49 | /* |
| 50 | * @lock: protects access to @access_bitmap, @done_bitmap and |
| 51 | * @frozen_read_reqs |
| 52 | */ |
| 53 | CoMutex lock; |
| 54 | |
| 55 | /* |
| 56 | * @access_bitmap: represents areas allowed for reading by fleecing user. |
| 57 | * Reading from non-dirty areas leads to -EACCES. |
| 58 | */ |
| 59 | BdrvDirtyBitmap *access_bitmap; |
| 60 | |
| 61 | /* |
| 62 | * @done_bitmap: represents areas that was successfully copied to @target by |
| 63 | * copy-before-write operations. |
| 64 | */ |
| 65 | BdrvDirtyBitmap *done_bitmap; |
| 66 | |
| 67 | /* |
| 68 | * @frozen_read_reqs: current read requests for fleecing user in bs->file |
| 69 | * node. These areas must not be rewritten by guest. There can be multiple |
| 70 | * overlapping read requests. |
| 71 | */ |
| 72 | BlockReqList frozen_read_reqs; |
| 73 | |
| 74 | /* |
| 75 | * @snapshot_error is normally zero. But on first copy-before-write failure |
| 76 | * when @on_cbw_error == ON_CBW_ERROR_BREAK_SNAPSHOT, @snapshot_error takes |
| 77 | * value of this error (<0). After that all in-flight and further |
| 78 | * snapshot-API requests will fail with that error. |
| 79 | */ |
| 80 | int snapshot_error; |
| 81 | } BDRVCopyBeforeWriteState; |
| 82 | |
| 83 | static int coroutine_fn GRAPH_RDLOCK |
| 84 | cbw_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes, |
| 85 | QEMUIOVector *qiov, BdrvRequestFlags flags) |
| 86 | { |
| 87 | return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags); |
| 88 | } |
| 89 | |
| 90 | static void block_copy_cb(void *opaque) |
| 91 | { |
| 92 | BlockDriverState *bs = opaque; |
| 93 | |
| 94 | bdrv_dec_in_flight(bs); |
| 95 | } |
| 96 | |
| 97 | /* |
| 98 | * Do copy-before-write operation. |
| 99 | * |
| 100 | * On failure guest request must be failed too. |
| 101 | * |
| 102 | * On success, we also wait for all in-flight fleecing read requests in source |
| 103 | * node, and it's guaranteed that after cbw_do_copy_before_write() successful |
| 104 | * return there are no such requests and they will never appear. |
| 105 | */ |
| 106 | static coroutine_fn int cbw_do_copy_before_write(BlockDriverState *bs, |
| 107 | uint64_t offset, uint64_t bytes, BdrvRequestFlags flags) |
| 108 | { |
| 109 | BDRVCopyBeforeWriteState *s = bs->opaque; |
| 110 | int ret; |
| 111 | uint64_t off, end; |
| 112 | int64_t cluster_size = block_copy_cluster_size(s->bcs); |
| 113 | |
| 114 | if (flags & BDRV_REQ_WRITE_UNCHANGED) { |
| 115 | return 0; |
| 116 | } |
| 117 | |
| 118 | if (s->snapshot_error) { |
| 119 | return 0; |
| 120 | } |
| 121 | |
| 122 | off = QEMU_ALIGN_DOWN(offset, cluster_size); |
| 123 | end = QEMU_ALIGN_UP(offset + bytes, cluster_size); |
| 124 | |
| 125 | /* |
| 126 | * Increase in_flight, so that in case of timed-out block-copy, the |
| 127 | * remaining background block_copy() request (which can't be immediately |
| 128 | * cancelled by timeout) is presented in bs->in_flight. This way we are |
| 129 | * sure that on bs close() we'll previously wait for all timed-out but yet |
| 130 | * running block_copy calls. |
| 131 | */ |
| 132 | bdrv_inc_in_flight(bs); |
| 133 | ret = block_copy(s->bcs, off, end - off, true, s->cbw_timeout_ns, |
| 134 | block_copy_cb, bs); |
| 135 | if (ret < 0 && s->on_cbw_error == ON_CBW_ERROR_BREAK_GUEST_WRITE) { |
| 136 | return ret; |
| 137 | } |
| 138 | |
| 139 | WITH_QEMU_LOCK_GUARD(&s->lock) { |
| 140 | if (ret < 0) { |
| 141 | assert(s->on_cbw_error == ON_CBW_ERROR_BREAK_SNAPSHOT); |
| 142 | if (!s->snapshot_error) { |
| 143 | s->snapshot_error = ret; |
| 144 | } |
| 145 | } else { |
| 146 | bdrv_set_dirty_bitmap(s->done_bitmap, off, end - off); |
| 147 | } |
| 148 | reqlist_wait_all(&s->frozen_read_reqs, off, end - off, &s->lock); |
| 149 | } |
| 150 | |
| 151 | return 0; |
| 152 | } |
| 153 | |
| 154 | static int coroutine_fn GRAPH_RDLOCK |
| 155 | cbw_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes) |
| 156 | { |
| 157 | int ret = cbw_do_copy_before_write(bs, offset, bytes, 0); |
| 158 | if (ret < 0) { |
| 159 | return ret; |
| 160 | } |
| 161 | |
| 162 | return bdrv_co_pdiscard(bs->file, offset, bytes); |
| 163 | } |
| 164 | |
| 165 | static int coroutine_fn GRAPH_RDLOCK |
| 166 | cbw_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int64_t bytes, |
| 167 | BdrvRequestFlags flags) |
| 168 | { |
| 169 | int ret = cbw_do_copy_before_write(bs, offset, bytes, flags); |
| 170 | if (ret < 0) { |
| 171 | return ret; |
| 172 | } |
| 173 | |
| 174 | return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags); |
| 175 | } |
| 176 | |
| 177 | static coroutine_fn GRAPH_RDLOCK |
| 178 | int cbw_co_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes, |
| 179 | QEMUIOVector *qiov, BdrvRequestFlags flags) |
| 180 | { |
| 181 | int ret = cbw_do_copy_before_write(bs, offset, bytes, flags); |
| 182 | if (ret < 0) { |
| 183 | return ret; |
| 184 | } |
| 185 | |
| 186 | return bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags); |
| 187 | } |
| 188 | |
| 189 | static int coroutine_fn GRAPH_RDLOCK cbw_co_flush(BlockDriverState *bs) |
| 190 | { |
| 191 | if (!bs->file) { |
| 192 | return 0; |
| 193 | } |
| 194 | |
| 195 | return bdrv_co_flush(bs->file->bs); |
| 196 | } |
| 197 | |
| 198 | /* |
| 199 | * If @offset not accessible - return NULL. |
| 200 | * |
| 201 | * Otherwise, set @pnum to some bytes that accessible from @file (@file is set |
| 202 | * to bs->file or to s->target). Return newly allocated BlockReq object that |
| 203 | * should be than passed to cbw_snapshot_read_unlock(). |
| 204 | * |
| 205 | * It's guaranteed that guest writes will not interact in the region until |
| 206 | * cbw_snapshot_read_unlock() called. |
| 207 | */ |
| 208 | static BlockReq * coroutine_fn GRAPH_RDLOCK |
| 209 | cbw_snapshot_read_lock(BlockDriverState *bs, int64_t offset, int64_t bytes, |
| 210 | int64_t *pnum, BdrvChild **file) |
| 211 | { |
| 212 | BDRVCopyBeforeWriteState *s = bs->opaque; |
| 213 | BlockReq *req = g_new(BlockReq, 1); |
| 214 | bool done; |
| 215 | |
| 216 | QEMU_LOCK_GUARD(&s->lock); |
| 217 | |
| 218 | if (s->snapshot_error) { |
| 219 | g_free(req); |
| 220 | return NULL; |
| 221 | } |
| 222 | |
| 223 | if (bdrv_dirty_bitmap_next_zero(s->access_bitmap, offset, bytes) != -1) { |
| 224 | g_free(req); |
| 225 | return NULL; |
| 226 | } |
| 227 | |
| 228 | done = bdrv_dirty_bitmap_status(s->done_bitmap, offset, bytes, pnum); |
| 229 | if (done) { |
| 230 | /* |
| 231 | * Special invalid BlockReq, that is handled in |
| 232 | * cbw_snapshot_read_unlock(). We don't need to lock something to read |
| 233 | * from s->target. |
| 234 | */ |
| 235 | *req = (BlockReq) {.offset = -1, .bytes = -1}; |
| 236 | *file = s->target; |
| 237 | } else { |
| 238 | reqlist_init_req(&s->frozen_read_reqs, req, offset, bytes); |
| 239 | *file = bs->file; |
| 240 | } |
| 241 | |
| 242 | return req; |
| 243 | } |
| 244 | |
| 245 | static coroutine_fn void |
| 246 | cbw_snapshot_read_unlock(BlockDriverState *bs, BlockReq *req) |
| 247 | { |
| 248 | BDRVCopyBeforeWriteState *s = bs->opaque; |
| 249 | |
| 250 | if (req->offset == -1 && req->bytes == -1) { |
| 251 | g_free(req); |
| 252 | return; |
| 253 | } |
| 254 | |
| 255 | QEMU_LOCK_GUARD(&s->lock); |
| 256 | |
| 257 | reqlist_remove_req(req); |
| 258 | g_free(req); |
| 259 | } |
| 260 | |
| 261 | static int coroutine_fn GRAPH_RDLOCK |
| 262 | cbw_co_preadv_snapshot(BlockDriverState *bs, int64_t offset, int64_t bytes, |
| 263 | QEMUIOVector *qiov, size_t qiov_offset) |
| 264 | { |
| 265 | BlockReq *req; |
| 266 | BdrvChild *file; |
| 267 | int ret; |
| 268 | |
| 269 | /* TODO: upgrade to async loop using AioTask */ |
| 270 | while (bytes) { |
| 271 | int64_t cur_bytes; |
| 272 | |
| 273 | req = cbw_snapshot_read_lock(bs, offset, bytes, &cur_bytes, &file); |
| 274 | if (!req) { |
| 275 | return -EACCES; |
| 276 | } |
| 277 | |
| 278 | ret = bdrv_co_preadv_part(file, offset, cur_bytes, |
| 279 | qiov, qiov_offset, 0); |
| 280 | cbw_snapshot_read_unlock(bs, req); |
| 281 | if (ret < 0) { |
| 282 | return ret; |
| 283 | } |
| 284 | |
| 285 | bytes -= cur_bytes; |
| 286 | offset += cur_bytes; |
| 287 | qiov_offset += cur_bytes; |
| 288 | } |
| 289 | |
| 290 | return 0; |
| 291 | } |
| 292 | |
| 293 | static int coroutine_fn GRAPH_RDLOCK |
| 294 | cbw_co_snapshot_block_status(BlockDriverState *bs, unsigned int mode, |
| 295 | int64_t offset, int64_t bytes, |
| 296 | int64_t *pnum, int64_t *map, |
| 297 | BlockDriverState **file) |
| 298 | { |
| 299 | BDRVCopyBeforeWriteState *s = bs->opaque; |
| 300 | BlockReq *req; |
| 301 | int ret; |
| 302 | int64_t cur_bytes; |
| 303 | BdrvChild *child; |
| 304 | |
| 305 | req = cbw_snapshot_read_lock(bs, offset, bytes, &cur_bytes, &child); |
| 306 | if (!req) { |
| 307 | return -EACCES; |
| 308 | } |
| 309 | |
| 310 | ret = bdrv_co_block_status(child->bs, offset, cur_bytes, pnum, map, file); |
| 311 | if (child == s->target) { |
| 312 | /* |
| 313 | * We refer to s->target only for areas that we've written to it. |
| 314 | * And we can not report unallocated blocks in s->target: this will |
| 315 | * break generic block-status-above logic, that will go to |
| 316 | * copy-before-write filtered child in this case. |
| 317 | */ |
| 318 | assert(ret & BDRV_BLOCK_ALLOCATED); |
| 319 | } |
| 320 | |
| 321 | cbw_snapshot_read_unlock(bs, req); |
| 322 | |
| 323 | return ret; |
| 324 | } |
| 325 | |
| 326 | static int coroutine_fn GRAPH_RDLOCK |
| 327 | cbw_co_pdiscard_snapshot(BlockDriverState *bs, int64_t offset, int64_t bytes) |
| 328 | { |
| 329 | BDRVCopyBeforeWriteState *s = bs->opaque; |
| 330 | uint32_t cluster_size = block_copy_cluster_size(s->bcs); |
| 331 | int64_t aligned_offset = QEMU_ALIGN_UP(offset, cluster_size); |
| 332 | int64_t aligned_end = QEMU_ALIGN_DOWN(offset + bytes, cluster_size); |
| 333 | int64_t aligned_bytes; |
| 334 | |
| 335 | if (aligned_end <= aligned_offset) { |
| 336 | return 0; |
| 337 | } |
| 338 | aligned_bytes = aligned_end - aligned_offset; |
| 339 | |
| 340 | WITH_QEMU_LOCK_GUARD(&s->lock) { |
| 341 | bdrv_reset_dirty_bitmap(s->access_bitmap, aligned_offset, |
| 342 | aligned_bytes); |
| 343 | } |
| 344 | |
| 345 | block_copy_reset(s->bcs, aligned_offset, aligned_bytes); |
| 346 | |
| 347 | return bdrv_co_pdiscard(s->target, aligned_offset, aligned_bytes); |
| 348 | } |
| 349 | |
| 350 | static void GRAPH_RDLOCK cbw_refresh_filename(BlockDriverState *bs) |
| 351 | { |
| 352 | pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), |
| 353 | bs->file->bs->filename); |
| 354 | } |
| 355 | |
| 356 | static void GRAPH_RDLOCK |
| 357 | cbw_child_perm(BlockDriverState *bs, BdrvChild *c, BdrvChildRole role, |
| 358 | BlockReopenQueue *reopen_queue, |
| 359 | uint64_t perm, uint64_t shared, |
| 360 | uint64_t *nperm, uint64_t *nshared) |
| 361 | { |
| 362 | BDRVCopyBeforeWriteState *s = bs->opaque; |
| 363 | |
| 364 | if (!(role & BDRV_CHILD_FILTERED)) { |
| 365 | /* |
| 366 | * Target child |
| 367 | * |
| 368 | * Share write to target (child_file), to not interfere |
| 369 | * with guest writes to its disk which may be in target backing chain. |
| 370 | * Can't resize during a backup block job because we check the size |
| 371 | * only upfront. |
| 372 | */ |
| 373 | *nshared = BLK_PERM_ALL & ~BLK_PERM_RESIZE; |
| 374 | *nperm = BLK_PERM_WRITE; |
| 375 | } else { |
| 376 | /* Source child */ |
| 377 | bdrv_default_perms(bs, c, role, reopen_queue, |
| 378 | perm, shared, nperm, nshared); |
| 379 | |
| 380 | if (!QLIST_EMPTY(&bs->parents)) { |
| 381 | /* |
| 382 | * Note, that source child may be shared with backup job. Backup job |
| 383 | * does create own blk parent on copy-before-write node, so this |
| 384 | * works even if source node does not have any parents before backup |
| 385 | * start |
| 386 | */ |
| 387 | *nperm = *nperm | BLK_PERM_CONSISTENT_READ; |
| 388 | if (s->discard_source) { |
| 389 | *nperm = *nperm | BLK_PERM_WRITE; |
| 390 | } |
| 391 | |
| 392 | *nshared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE); |
| 393 | } |
| 394 | } |
| 395 | } |
| 396 | |
| 397 | static BlockdevOptions *cbw_parse_options(QDict *options, Error **errp) |
| 398 | { |
| 399 | BlockdevOptions *opts = NULL; |
| 400 | Visitor *v = NULL; |
| 401 | |
| 402 | qdict_put_str(options, "driver", "copy-before-write"); |
| 403 | |
| 404 | v = qobject_input_visitor_new_flat_confused(options, errp); |
| 405 | if (!v) { |
| 406 | goto out; |
| 407 | } |
| 408 | |
| 409 | visit_type_BlockdevOptions(v, NULL, &opts, errp); |
| 410 | if (!opts) { |
| 411 | goto out; |
| 412 | } |
| 413 | |
| 414 | /* |
| 415 | * Delete options which we are going to parse through BlockdevOptions |
| 416 | * object for original options. |
| 417 | */ |
| 418 | qdict_extract_subqdict(options, NULL, "bitmap"); |
| 419 | qdict_del(options, "on-cbw-error"); |
| 420 | qdict_del(options, "cbw-timeout"); |
| 421 | qdict_del(options, "min-cluster-size"); |
| 422 | |
| 423 | out: |
| 424 | visit_free(v); |
| 425 | qdict_del(options, "driver"); |
| 426 | |
| 427 | return opts; |
| 428 | } |
| 429 | |
| 430 | static int cbw_open(BlockDriverState *bs, QDict *options, int flags, |
| 431 | Error **errp) |
| 432 | { |
| 433 | ERRP_GUARD(); |
| 434 | BDRVCopyBeforeWriteState *s = bs->opaque; |
| 435 | BdrvDirtyBitmap *bitmap = NULL; |
| 436 | int64_t cluster_size; |
| 437 | g_autoptr(BlockdevOptions) full_opts = NULL; |
| 438 | BlockdevOptionsCbw *opts; |
| 439 | int ret; |
| 440 | |
| 441 | full_opts = cbw_parse_options(options, errp); |
| 442 | if (!full_opts) { |
| 443 | return -EINVAL; |
| 444 | } |
| 445 | assert(full_opts->driver == BLOCKDEV_DRIVER_COPY_BEFORE_WRITE); |
| 446 | opts = &full_opts->u.copy_before_write; |
| 447 | |
| 448 | ret = bdrv_open_file_child(NULL, options, "file", bs, errp); |
| 449 | if (ret < 0) { |
| 450 | return ret; |
| 451 | } |
| 452 | |
| 453 | s->target = bdrv_open_child(NULL, options, "target", bs, &child_of_bds, |
| 454 | BDRV_CHILD_DATA, false, errp); |
| 455 | if (!s->target) { |
| 456 | return -EINVAL; |
| 457 | } |
| 458 | |
| 459 | GRAPH_RDLOCK_GUARD_MAINLOOP(); |
| 460 | |
| 461 | if (opts->bitmap) { |
| 462 | bitmap = block_dirty_bitmap_lookup(opts->bitmap->node, |
| 463 | opts->bitmap->name, NULL, errp); |
| 464 | if (!bitmap) { |
| 465 | return -EINVAL; |
| 466 | } |
| 467 | } |
| 468 | s->on_cbw_error = opts->has_on_cbw_error ? opts->on_cbw_error : |
| 469 | ON_CBW_ERROR_BREAK_GUEST_WRITE; |
| 470 | s->cbw_timeout_ns = opts->has_cbw_timeout ? |
| 471 | opts->cbw_timeout * NANOSECONDS_PER_SECOND : 0; |
| 472 | |
| 473 | bs->total_sectors = bs->file->bs->total_sectors; |
| 474 | bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED | |
| 475 | (BDRV_REQ_FUA & bs->file->bs->supported_write_flags); |
| 476 | bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED | |
| 477 | ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) & |
| 478 | bs->file->bs->supported_zero_flags); |
| 479 | |
| 480 | s->discard_source = flags & BDRV_O_CBW_DISCARD_SOURCE; |
| 481 | |
| 482 | s->bcs = block_copy_state_new(bs->file, s->target, bs, bitmap, |
| 483 | flags & BDRV_O_CBW_DISCARD_SOURCE, |
| 484 | opts->min_cluster_size, errp); |
| 485 | if (!s->bcs) { |
| 486 | error_prepend(errp, "Cannot create block-copy-state: "); |
| 487 | return -EINVAL; |
| 488 | } |
| 489 | |
| 490 | cluster_size = block_copy_cluster_size(s->bcs); |
| 491 | |
| 492 | s->done_bitmap = bdrv_create_dirty_bitmap(bs, cluster_size, NULL, errp); |
| 493 | if (!s->done_bitmap) { |
| 494 | return -EINVAL; |
| 495 | } |
| 496 | bdrv_disable_dirty_bitmap(s->done_bitmap); |
| 497 | |
| 498 | /* s->access_bitmap starts equal to bcs bitmap */ |
| 499 | s->access_bitmap = bdrv_create_dirty_bitmap(bs, cluster_size, NULL, errp); |
| 500 | if (!s->access_bitmap) { |
| 501 | return -EINVAL; |
| 502 | } |
| 503 | bdrv_disable_dirty_bitmap(s->access_bitmap); |
| 504 | bdrv_dirty_bitmap_merge_internal(s->access_bitmap, |
| 505 | block_copy_dirty_bitmap(s->bcs), NULL, |
| 506 | true); |
| 507 | |
| 508 | qemu_co_mutex_init(&s->lock); |
| 509 | QLIST_INIT(&s->frozen_read_reqs); |
| 510 | return 0; |
| 511 | } |
| 512 | |
| 513 | static void cbw_close(BlockDriverState *bs) |
| 514 | { |
| 515 | BDRVCopyBeforeWriteState *s = bs->opaque; |
| 516 | |
| 517 | bdrv_release_dirty_bitmap(s->access_bitmap); |
| 518 | bdrv_release_dirty_bitmap(s->done_bitmap); |
| 519 | |
| 520 | block_copy_state_free(s->bcs); |
| 521 | s->bcs = NULL; |
| 522 | } |
| 523 | |
| 524 | static BlockDriver bdrv_cbw_filter = { |
| 525 | .format_name = "copy-before-write", |
| 526 | .instance_size = sizeof(BDRVCopyBeforeWriteState), |
| 527 | |
| 528 | .bdrv_open = cbw_open, |
| 529 | .bdrv_close = cbw_close, |
| 530 | |
| 531 | .bdrv_co_preadv = cbw_co_preadv, |
| 532 | .bdrv_co_pwritev = cbw_co_pwritev, |
| 533 | .bdrv_co_pwrite_zeroes = cbw_co_pwrite_zeroes, |
| 534 | .bdrv_co_pdiscard = cbw_co_pdiscard, |
| 535 | .bdrv_co_flush = cbw_co_flush, |
| 536 | |
| 537 | .bdrv_co_preadv_snapshot = cbw_co_preadv_snapshot, |
| 538 | .bdrv_co_pdiscard_snapshot = cbw_co_pdiscard_snapshot, |
| 539 | .bdrv_co_snapshot_block_status = cbw_co_snapshot_block_status, |
| 540 | |
| 541 | .bdrv_refresh_filename = cbw_refresh_filename, |
| 542 | |
| 543 | .bdrv_child_perm = cbw_child_perm, |
| 544 | |
| 545 | .is_filter = true, |
| 546 | }; |
| 547 | |
| 548 | BlockDriverState *bdrv_cbw_append(BlockDriverState *source, |
| 549 | BlockDriverState *target, |
| 550 | const char *filter_node_name, |
| 551 | bool discard_source, |
| 552 | uint64_t min_cluster_size, |
| 553 | BlockCopyState **bcs, |
| 554 | OnCbwError on_cbw_error, |
| 555 | Error **errp) |
| 556 | { |
| 557 | BDRVCopyBeforeWriteState *state; |
| 558 | BlockDriverState *top; |
| 559 | QDict *opts; |
| 560 | int flags = BDRV_O_RDWR | (discard_source ? BDRV_O_CBW_DISCARD_SOURCE : 0); |
| 561 | |
| 562 | assert(source->total_sectors == target->total_sectors); |
| 563 | GLOBAL_STATE_CODE(); |
| 564 | |
| 565 | opts = qdict_new(); |
| 566 | qdict_put_str(opts, "driver", "copy-before-write"); |
| 567 | if (filter_node_name) { |
| 568 | qdict_put_str(opts, "node-name", filter_node_name); |
| 569 | } |
| 570 | qdict_put_str(opts, "file", bdrv_get_node_name(source)); |
| 571 | qdict_put_str(opts, "target", bdrv_get_node_name(target)); |
| 572 | qdict_put_str(opts, "on-cbw-error", OnCbwError_str(on_cbw_error)); |
| 573 | |
| 574 | if (min_cluster_size > INT64_MAX) { |
| 575 | error_setg(errp, "min-cluster-size too large: %" PRIu64 " > %" PRIi64, |
| 576 | min_cluster_size, INT64_MAX); |
| 577 | qobject_unref(opts); |
| 578 | return NULL; |
| 579 | } |
| 580 | qdict_put_int(opts, "min-cluster-size", (int64_t)min_cluster_size); |
| 581 | |
| 582 | top = bdrv_insert_node(source, opts, flags, errp); |
| 583 | if (!top) { |
| 584 | return NULL; |
| 585 | } |
| 586 | |
| 587 | state = top->opaque; |
| 588 | *bcs = state->bcs; |
| 589 | |
| 590 | return top; |
| 591 | } |
| 592 | |
| 593 | void bdrv_cbw_drop(BlockDriverState *bs) |
| 594 | { |
| 595 | GLOBAL_STATE_CODE(); |
| 596 | bdrv_drop_filter(bs, &error_abort); |
| 597 | bdrv_unref(bs); |
| 598 | } |
| 599 | |
| 600 | static void cbw_init(void) |
| 601 | { |
| 602 | bdrv_register(&bdrv_cbw_filter); |
| 603 | } |
| 604 | |
| 605 | block_init(cbw_init); |