1 /* 2 * Image mirroring 3 * 4 * Copyright Red Hat, Inc. 2012 5 * 6 * Authors: 7 * Paolo Bonzini <pbonzini@redhat.com> 8 * 9 * This work is licensed under the terms of the GNU LGPL, version 2 or later. 10 * See the COPYING.LIB file in the top-level directory. 11 * 12 */ 13 14 #include "qemu/osdep.h" 15 #include "qemu/cutils.h" 16 #include "qemu/coroutine.h" 17 #include "qemu/range.h" 18 #include "trace.h" 19 #include "block/blockjob_int.h" 20 #include "block/block_int.h" 21 #include "block/dirty-bitmap.h" 22 #include "sysemu/block-backend.h" 23 #include "qapi/error.h" 24 #include "qemu/ratelimit.h" 25 #include "qemu/bitmap.h" 26 #include "qemu/memalign.h" 27 28 #define MAX_IN_FLIGHT 16 29 #define MAX_IO_BYTES (1 << 20) /* 1 Mb */ 30 #define DEFAULT_MIRROR_BUF_SIZE (MAX_IN_FLIGHT * MAX_IO_BYTES) 31 32 /* The mirroring buffer is a list of granularity-sized chunks. 33 * Free chunks are organized in a list. 34 */ 35 typedef struct MirrorBuffer { 36 QSIMPLEQ_ENTRY(MirrorBuffer) next; 37 } MirrorBuffer; 38 39 typedef struct MirrorOp MirrorOp; 40 41 typedef struct MirrorBlockJob { 42 BlockJob common; 43 BlockBackend *target; 44 BlockDriverState *mirror_top_bs; 45 BlockDriverState *base; 46 BlockDriverState *base_overlay; 47 48 /* The name of the graph node to replace */ 49 char *replaces; 50 /* The BDS to replace */ 51 BlockDriverState *to_replace; 52 /* Used to block operations on the drive-mirror-replace target */ 53 Error *replace_blocker; 54 bool is_none_mode; 55 BlockMirrorBackingMode backing_mode; 56 /* Whether the target image requires explicit zero-initialization */ 57 bool zero_target; 58 MirrorCopyMode copy_mode; 59 BlockdevOnError on_source_error, on_target_error; 60 /* Set when the target is synced (dirty bitmap is clean, nothing 61 * in flight) and the job is running in active mode */ 62 bool actively_synced; 63 bool should_complete; 64 int64_t granularity; 65 size_t buf_size; 66 int64_t bdev_length; 67 unsigned long *cow_bitmap; 68 BdrvDirtyBitmap *dirty_bitmap; 69 BdrvDirtyBitmapIter *dbi; 70 uint8_t *buf; 71 QSIMPLEQ_HEAD(, MirrorBuffer) buf_free; 72 int buf_free_count; 73 74 uint64_t last_pause_ns; 75 unsigned long *in_flight_bitmap; 76 unsigned in_flight; 77 int64_t bytes_in_flight; 78 QTAILQ_HEAD(, MirrorOp) ops_in_flight; 79 int ret; 80 bool unmap; 81 int target_cluster_size; 82 int max_iov; 83 bool initial_zeroing_ongoing; 84 int in_active_write_counter; 85 int64_t active_write_bytes_in_flight; 86 bool prepared; 87 bool in_drain; 88 } MirrorBlockJob; 89 90 typedef struct MirrorBDSOpaque { 91 MirrorBlockJob *job; 92 bool stop; 93 bool is_commit; 94 } MirrorBDSOpaque; 95 96 struct MirrorOp { 97 MirrorBlockJob *s; 98 QEMUIOVector qiov; 99 int64_t offset; 100 uint64_t bytes; 101 102 /* The pointee is set by mirror_co_read(), mirror_co_zero(), and 103 * mirror_co_discard() before yielding for the first time */ 104 int64_t *bytes_handled; 105 106 bool is_pseudo_op; 107 bool is_active_write; 108 bool is_in_flight; 109 CoQueue waiting_requests; 110 Coroutine *co; 111 MirrorOp *waiting_for_op; 112 113 QTAILQ_ENTRY(MirrorOp) next; 114 }; 115 116 typedef enum MirrorMethod { 117 MIRROR_METHOD_COPY, 118 MIRROR_METHOD_ZERO, 119 MIRROR_METHOD_DISCARD, 120 } MirrorMethod; 121 122 static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, 123 int error) 124 { 125 s->actively_synced = false; 126 if (read) { 127 return block_job_error_action(&s->common, s->on_source_error, 128 true, error); 129 } else { 130 return block_job_error_action(&s->common, s->on_target_error, 131 false, error); 132 } 133 } 134 135 static void coroutine_fn mirror_wait_on_conflicts(MirrorOp *self, 136 MirrorBlockJob *s, 137 uint64_t offset, 138 uint64_t bytes) 139 { 140 uint64_t self_start_chunk = offset / s->granularity; 141 uint64_t self_end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 142 uint64_t self_nb_chunks = self_end_chunk - self_start_chunk; 143 144 while (find_next_bit(s->in_flight_bitmap, self_end_chunk, 145 self_start_chunk) < self_end_chunk && 146 s->ret >= 0) 147 { 148 MirrorOp *op; 149 150 QTAILQ_FOREACH(op, &s->ops_in_flight, next) { 151 uint64_t op_start_chunk = op->offset / s->granularity; 152 uint64_t op_nb_chunks = DIV_ROUND_UP(op->offset + op->bytes, 153 s->granularity) - 154 op_start_chunk; 155 156 if (op == self) { 157 continue; 158 } 159 160 if (ranges_overlap(self_start_chunk, self_nb_chunks, 161 op_start_chunk, op_nb_chunks)) 162 { 163 if (self) { 164 /* 165 * If the operation is already (indirectly) waiting for us, 166 * or will wait for us as soon as it wakes up, then just go 167 * on (instead of producing a deadlock in the former case). 168 */ 169 if (op->waiting_for_op) { 170 continue; 171 } 172 173 self->waiting_for_op = op; 174 } 175 176 qemu_co_queue_wait(&op->waiting_requests, NULL); 177 178 if (self) { 179 self->waiting_for_op = NULL; 180 } 181 182 break; 183 } 184 } 185 } 186 } 187 188 static void coroutine_fn mirror_iteration_done(MirrorOp *op, int ret) 189 { 190 MirrorBlockJob *s = op->s; 191 struct iovec *iov; 192 int64_t chunk_num; 193 int i, nb_chunks; 194 195 trace_mirror_iteration_done(s, op->offset, op->bytes, ret); 196 197 s->in_flight--; 198 s->bytes_in_flight -= op->bytes; 199 iov = op->qiov.iov; 200 for (i = 0; i < op->qiov.niov; i++) { 201 MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base; 202 QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next); 203 s->buf_free_count++; 204 } 205 206 chunk_num = op->offset / s->granularity; 207 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity); 208 209 bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks); 210 QTAILQ_REMOVE(&s->ops_in_flight, op, next); 211 if (ret >= 0) { 212 if (s->cow_bitmap) { 213 bitmap_set(s->cow_bitmap, chunk_num, nb_chunks); 214 } 215 if (!s->initial_zeroing_ongoing) { 216 job_progress_update(&s->common.job, op->bytes); 217 } 218 } 219 qemu_iovec_destroy(&op->qiov); 220 221 qemu_co_queue_restart_all(&op->waiting_requests); 222 g_free(op); 223 } 224 225 static void coroutine_fn mirror_write_complete(MirrorOp *op, int ret) 226 { 227 MirrorBlockJob *s = op->s; 228 229 if (ret < 0) { 230 BlockErrorAction action; 231 232 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes); 233 action = mirror_error_action(s, false, -ret); 234 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 235 s->ret = ret; 236 } 237 } 238 239 mirror_iteration_done(op, ret); 240 } 241 242 static void coroutine_fn mirror_read_complete(MirrorOp *op, int ret) 243 { 244 MirrorBlockJob *s = op->s; 245 246 if (ret < 0) { 247 BlockErrorAction action; 248 249 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes); 250 action = mirror_error_action(s, true, -ret); 251 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 252 s->ret = ret; 253 } 254 255 mirror_iteration_done(op, ret); 256 return; 257 } 258 259 ret = blk_co_pwritev(s->target, op->offset, op->qiov.size, &op->qiov, 0); 260 mirror_write_complete(op, ret); 261 } 262 263 /* Clip bytes relative to offset to not exceed end-of-file */ 264 static inline int64_t mirror_clip_bytes(MirrorBlockJob *s, 265 int64_t offset, 266 int64_t bytes) 267 { 268 return MIN(bytes, s->bdev_length - offset); 269 } 270 271 /* Round offset and/or bytes to target cluster if COW is needed, and 272 * return the offset of the adjusted tail against original. */ 273 static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset, 274 uint64_t *bytes) 275 { 276 bool need_cow; 277 int ret = 0; 278 int64_t align_offset = *offset; 279 int64_t align_bytes = *bytes; 280 int max_bytes = s->granularity * s->max_iov; 281 282 need_cow = !test_bit(*offset / s->granularity, s->cow_bitmap); 283 need_cow |= !test_bit((*offset + *bytes - 1) / s->granularity, 284 s->cow_bitmap); 285 if (need_cow) { 286 bdrv_round_to_clusters(blk_bs(s->target), *offset, *bytes, 287 &align_offset, &align_bytes); 288 } 289 290 if (align_bytes > max_bytes) { 291 align_bytes = max_bytes; 292 if (need_cow) { 293 align_bytes = QEMU_ALIGN_DOWN(align_bytes, s->target_cluster_size); 294 } 295 } 296 /* Clipping may result in align_bytes unaligned to chunk boundary, but 297 * that doesn't matter because it's already the end of source image. */ 298 align_bytes = mirror_clip_bytes(s, align_offset, align_bytes); 299 300 ret = align_offset + align_bytes - (*offset + *bytes); 301 *offset = align_offset; 302 *bytes = align_bytes; 303 assert(ret >= 0); 304 return ret; 305 } 306 307 static inline void coroutine_fn 308 mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s) 309 { 310 MirrorOp *op; 311 312 QTAILQ_FOREACH(op, &s->ops_in_flight, next) { 313 /* 314 * Do not wait on pseudo ops, because it may in turn wait on 315 * some other operation to start, which may in fact be the 316 * caller of this function. Since there is only one pseudo op 317 * at any given time, we will always find some real operation 318 * to wait on. 319 * Also, do not wait on active operations, because they do not 320 * use up in-flight slots. 321 */ 322 if (!op->is_pseudo_op && op->is_in_flight && !op->is_active_write) { 323 qemu_co_queue_wait(&op->waiting_requests, NULL); 324 return; 325 } 326 } 327 abort(); 328 } 329 330 /* Perform a mirror copy operation. 331 * 332 * *op->bytes_handled is set to the number of bytes copied after and 333 * including offset, excluding any bytes copied prior to offset due 334 * to alignment. This will be op->bytes if no alignment is necessary, 335 * or (new_end - op->offset) if the tail is rounded up or down due to 336 * alignment or buffer limit. 337 */ 338 static void coroutine_fn mirror_co_read(void *opaque) 339 { 340 MirrorOp *op = opaque; 341 MirrorBlockJob *s = op->s; 342 int nb_chunks; 343 uint64_t ret; 344 uint64_t max_bytes; 345 346 max_bytes = s->granularity * s->max_iov; 347 348 /* We can only handle as much as buf_size at a time. */ 349 op->bytes = MIN(s->buf_size, MIN(max_bytes, op->bytes)); 350 assert(op->bytes); 351 assert(op->bytes < BDRV_REQUEST_MAX_BYTES); 352 *op->bytes_handled = op->bytes; 353 354 if (s->cow_bitmap) { 355 *op->bytes_handled += mirror_cow_align(s, &op->offset, &op->bytes); 356 } 357 /* Cannot exceed BDRV_REQUEST_MAX_BYTES + INT_MAX */ 358 assert(*op->bytes_handled <= UINT_MAX); 359 assert(op->bytes <= s->buf_size); 360 /* The offset is granularity-aligned because: 361 * 1) Caller passes in aligned values; 362 * 2) mirror_cow_align is used only when target cluster is larger. */ 363 assert(QEMU_IS_ALIGNED(op->offset, s->granularity)); 364 /* The range is sector-aligned, since bdrv_getlength() rounds up. */ 365 assert(QEMU_IS_ALIGNED(op->bytes, BDRV_SECTOR_SIZE)); 366 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity); 367 368 while (s->buf_free_count < nb_chunks) { 369 trace_mirror_yield_in_flight(s, op->offset, s->in_flight); 370 mirror_wait_for_free_in_flight_slot(s); 371 } 372 373 /* Now make a QEMUIOVector taking enough granularity-sized chunks 374 * from s->buf_free. 375 */ 376 qemu_iovec_init(&op->qiov, nb_chunks); 377 while (nb_chunks-- > 0) { 378 MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free); 379 size_t remaining = op->bytes - op->qiov.size; 380 381 QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next); 382 s->buf_free_count--; 383 qemu_iovec_add(&op->qiov, buf, MIN(s->granularity, remaining)); 384 } 385 386 /* Copy the dirty cluster. */ 387 s->in_flight++; 388 s->bytes_in_flight += op->bytes; 389 op->is_in_flight = true; 390 trace_mirror_one_iteration(s, op->offset, op->bytes); 391 392 ret = bdrv_co_preadv(s->mirror_top_bs->backing, op->offset, op->bytes, 393 &op->qiov, 0); 394 mirror_read_complete(op, ret); 395 } 396 397 static void coroutine_fn mirror_co_zero(void *opaque) 398 { 399 MirrorOp *op = opaque; 400 int ret; 401 402 op->s->in_flight++; 403 op->s->bytes_in_flight += op->bytes; 404 *op->bytes_handled = op->bytes; 405 op->is_in_flight = true; 406 407 ret = blk_co_pwrite_zeroes(op->s->target, op->offset, op->bytes, 408 op->s->unmap ? BDRV_REQ_MAY_UNMAP : 0); 409 mirror_write_complete(op, ret); 410 } 411 412 static void coroutine_fn mirror_co_discard(void *opaque) 413 { 414 MirrorOp *op = opaque; 415 int ret; 416 417 op->s->in_flight++; 418 op->s->bytes_in_flight += op->bytes; 419 *op->bytes_handled = op->bytes; 420 op->is_in_flight = true; 421 422 ret = blk_co_pdiscard(op->s->target, op->offset, op->bytes); 423 mirror_write_complete(op, ret); 424 } 425 426 static unsigned mirror_perform(MirrorBlockJob *s, int64_t offset, 427 unsigned bytes, MirrorMethod mirror_method) 428 { 429 MirrorOp *op; 430 Coroutine *co; 431 int64_t bytes_handled = -1; 432 433 op = g_new(MirrorOp, 1); 434 *op = (MirrorOp){ 435 .s = s, 436 .offset = offset, 437 .bytes = bytes, 438 .bytes_handled = &bytes_handled, 439 }; 440 qemu_co_queue_init(&op->waiting_requests); 441 442 switch (mirror_method) { 443 case MIRROR_METHOD_COPY: 444 co = qemu_coroutine_create(mirror_co_read, op); 445 break; 446 case MIRROR_METHOD_ZERO: 447 co = qemu_coroutine_create(mirror_co_zero, op); 448 break; 449 case MIRROR_METHOD_DISCARD: 450 co = qemu_coroutine_create(mirror_co_discard, op); 451 break; 452 default: 453 abort(); 454 } 455 op->co = co; 456 457 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 458 qemu_coroutine_enter(co); 459 /* At this point, ownership of op has been moved to the coroutine 460 * and the object may already be freed */ 461 462 /* Assert that this value has been set */ 463 assert(bytes_handled >= 0); 464 465 /* Same assertion as in mirror_co_read() (and for mirror_co_read() 466 * and mirror_co_discard(), bytes_handled == op->bytes, which 467 * is the @bytes parameter given to this function) */ 468 assert(bytes_handled <= UINT_MAX); 469 return bytes_handled; 470 } 471 472 static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) 473 { 474 BlockDriverState *source = s->mirror_top_bs->backing->bs; 475 MirrorOp *pseudo_op; 476 int64_t offset; 477 uint64_t delay_ns = 0, ret = 0; 478 /* At least the first dirty chunk is mirrored in one iteration. */ 479 int nb_chunks = 1; 480 bool write_zeroes_ok = bdrv_can_write_zeroes_with_unmap(blk_bs(s->target)); 481 int max_io_bytes = MAX(s->buf_size / MAX_IN_FLIGHT, MAX_IO_BYTES); 482 483 bdrv_dirty_bitmap_lock(s->dirty_bitmap); 484 offset = bdrv_dirty_iter_next(s->dbi); 485 if (offset < 0) { 486 bdrv_set_dirty_iter(s->dbi, 0); 487 offset = bdrv_dirty_iter_next(s->dbi); 488 trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap)); 489 assert(offset >= 0); 490 } 491 bdrv_dirty_bitmap_unlock(s->dirty_bitmap); 492 493 /* 494 * Wait for concurrent requests to @offset. The next loop will limit the 495 * copied area based on in_flight_bitmap so we only copy an area that does 496 * not overlap with concurrent in-flight requests. Still, we would like to 497 * copy something, so wait until there are at least no more requests to the 498 * very beginning of the area. 499 */ 500 mirror_wait_on_conflicts(NULL, s, offset, 1); 501 502 job_pause_point(&s->common.job); 503 504 /* Find the number of consective dirty chunks following the first dirty 505 * one, and wait for in flight requests in them. */ 506 bdrv_dirty_bitmap_lock(s->dirty_bitmap); 507 while (nb_chunks * s->granularity < s->buf_size) { 508 int64_t next_dirty; 509 int64_t next_offset = offset + nb_chunks * s->granularity; 510 int64_t next_chunk = next_offset / s->granularity; 511 if (next_offset >= s->bdev_length || 512 !bdrv_dirty_bitmap_get_locked(s->dirty_bitmap, next_offset)) { 513 break; 514 } 515 if (test_bit(next_chunk, s->in_flight_bitmap)) { 516 break; 517 } 518 519 next_dirty = bdrv_dirty_iter_next(s->dbi); 520 if (next_dirty > next_offset || next_dirty < 0) { 521 /* The bitmap iterator's cache is stale, refresh it */ 522 bdrv_set_dirty_iter(s->dbi, next_offset); 523 next_dirty = bdrv_dirty_iter_next(s->dbi); 524 } 525 assert(next_dirty == next_offset); 526 nb_chunks++; 527 } 528 529 /* Clear dirty bits before querying the block status, because 530 * calling bdrv_block_status_above could yield - if some blocks are 531 * marked dirty in this window, we need to know. 532 */ 533 bdrv_reset_dirty_bitmap_locked(s->dirty_bitmap, offset, 534 nb_chunks * s->granularity); 535 bdrv_dirty_bitmap_unlock(s->dirty_bitmap); 536 537 /* Before claiming an area in the in-flight bitmap, we have to 538 * create a MirrorOp for it so that conflicting requests can wait 539 * for it. mirror_perform() will create the real MirrorOps later, 540 * for now we just create a pseudo operation that will wake up all 541 * conflicting requests once all real operations have been 542 * launched. */ 543 pseudo_op = g_new(MirrorOp, 1); 544 *pseudo_op = (MirrorOp){ 545 .offset = offset, 546 .bytes = nb_chunks * s->granularity, 547 .is_pseudo_op = true, 548 }; 549 qemu_co_queue_init(&pseudo_op->waiting_requests); 550 QTAILQ_INSERT_TAIL(&s->ops_in_flight, pseudo_op, next); 551 552 bitmap_set(s->in_flight_bitmap, offset / s->granularity, nb_chunks); 553 while (nb_chunks > 0 && offset < s->bdev_length) { 554 int ret; 555 int64_t io_bytes; 556 int64_t io_bytes_acct; 557 MirrorMethod mirror_method = MIRROR_METHOD_COPY; 558 559 assert(!(offset % s->granularity)); 560 ret = bdrv_block_status_above(source, NULL, offset, 561 nb_chunks * s->granularity, 562 &io_bytes, NULL, NULL); 563 if (ret < 0) { 564 io_bytes = MIN(nb_chunks * s->granularity, max_io_bytes); 565 } else if (ret & BDRV_BLOCK_DATA) { 566 io_bytes = MIN(io_bytes, max_io_bytes); 567 } 568 569 io_bytes -= io_bytes % s->granularity; 570 if (io_bytes < s->granularity) { 571 io_bytes = s->granularity; 572 } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) { 573 int64_t target_offset; 574 int64_t target_bytes; 575 bdrv_round_to_clusters(blk_bs(s->target), offset, io_bytes, 576 &target_offset, &target_bytes); 577 if (target_offset == offset && 578 target_bytes == io_bytes) { 579 mirror_method = ret & BDRV_BLOCK_ZERO ? 580 MIRROR_METHOD_ZERO : 581 MIRROR_METHOD_DISCARD; 582 } 583 } 584 585 while (s->in_flight >= MAX_IN_FLIGHT) { 586 trace_mirror_yield_in_flight(s, offset, s->in_flight); 587 mirror_wait_for_free_in_flight_slot(s); 588 } 589 590 if (s->ret < 0) { 591 ret = 0; 592 goto fail; 593 } 594 595 io_bytes = mirror_clip_bytes(s, offset, io_bytes); 596 io_bytes = mirror_perform(s, offset, io_bytes, mirror_method); 597 if (mirror_method != MIRROR_METHOD_COPY && write_zeroes_ok) { 598 io_bytes_acct = 0; 599 } else { 600 io_bytes_acct = io_bytes; 601 } 602 assert(io_bytes); 603 offset += io_bytes; 604 nb_chunks -= DIV_ROUND_UP(io_bytes, s->granularity); 605 delay_ns = block_job_ratelimit_get_delay(&s->common, io_bytes_acct); 606 } 607 608 ret = delay_ns; 609 fail: 610 QTAILQ_REMOVE(&s->ops_in_flight, pseudo_op, next); 611 qemu_co_queue_restart_all(&pseudo_op->waiting_requests); 612 g_free(pseudo_op); 613 614 return ret; 615 } 616 617 static void mirror_free_init(MirrorBlockJob *s) 618 { 619 int granularity = s->granularity; 620 size_t buf_size = s->buf_size; 621 uint8_t *buf = s->buf; 622 623 assert(s->buf_free_count == 0); 624 QSIMPLEQ_INIT(&s->buf_free); 625 while (buf_size != 0) { 626 MirrorBuffer *cur = (MirrorBuffer *)buf; 627 QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); 628 s->buf_free_count++; 629 buf_size -= granularity; 630 buf += granularity; 631 } 632 } 633 634 /* This is also used for the .pause callback. There is no matching 635 * mirror_resume() because mirror_run() will begin iterating again 636 * when the job is resumed. 637 */ 638 static void coroutine_fn mirror_wait_for_all_io(MirrorBlockJob *s) 639 { 640 while (s->in_flight > 0) { 641 mirror_wait_for_free_in_flight_slot(s); 642 } 643 } 644 645 /** 646 * mirror_exit_common: handle both abort() and prepare() cases. 647 * for .prepare, returns 0 on success and -errno on failure. 648 * for .abort cases, denoted by abort = true, MUST return 0. 649 */ 650 static int mirror_exit_common(Job *job) 651 { 652 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 653 BlockJob *bjob = &s->common; 654 MirrorBDSOpaque *bs_opaque; 655 AioContext *replace_aio_context = NULL; 656 BlockDriverState *src; 657 BlockDriverState *target_bs; 658 BlockDriverState *mirror_top_bs; 659 Error *local_err = NULL; 660 bool abort = job->ret < 0; 661 int ret = 0; 662 663 if (s->prepared) { 664 return 0; 665 } 666 s->prepared = true; 667 668 mirror_top_bs = s->mirror_top_bs; 669 bs_opaque = mirror_top_bs->opaque; 670 src = mirror_top_bs->backing->bs; 671 target_bs = blk_bs(s->target); 672 673 if (bdrv_chain_contains(src, target_bs)) { 674 bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs); 675 } 676 677 bdrv_release_dirty_bitmap(s->dirty_bitmap); 678 679 /* Make sure that the source BDS doesn't go away during bdrv_replace_node, 680 * before we can call bdrv_drained_end */ 681 bdrv_ref(src); 682 bdrv_ref(mirror_top_bs); 683 bdrv_ref(target_bs); 684 685 /* 686 * Remove target parent that still uses BLK_PERM_WRITE/RESIZE before 687 * inserting target_bs at s->to_replace, where we might not be able to get 688 * these permissions. 689 */ 690 blk_unref(s->target); 691 s->target = NULL; 692 693 /* We don't access the source any more. Dropping any WRITE/RESIZE is 694 * required before it could become a backing file of target_bs. Not having 695 * these permissions any more means that we can't allow any new requests on 696 * mirror_top_bs from now on, so keep it drained. */ 697 bdrv_drained_begin(mirror_top_bs); 698 bs_opaque->stop = true; 699 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 700 &error_abort); 701 if (!abort && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { 702 BlockDriverState *backing = s->is_none_mode ? src : s->base; 703 BlockDriverState *unfiltered_target = bdrv_skip_filters(target_bs); 704 705 if (bdrv_cow_bs(unfiltered_target) != backing) { 706 bdrv_set_backing_hd(unfiltered_target, backing, &local_err); 707 if (local_err) { 708 error_report_err(local_err); 709 local_err = NULL; 710 ret = -EPERM; 711 } 712 } 713 } else if (!abort && s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { 714 assert(!bdrv_backing_chain_next(target_bs)); 715 ret = bdrv_open_backing_file(bdrv_skip_filters(target_bs), NULL, 716 "backing", &local_err); 717 if (ret < 0) { 718 error_report_err(local_err); 719 local_err = NULL; 720 } 721 } 722 723 if (s->to_replace) { 724 replace_aio_context = bdrv_get_aio_context(s->to_replace); 725 aio_context_acquire(replace_aio_context); 726 } 727 728 if (s->should_complete && !abort) { 729 BlockDriverState *to_replace = s->to_replace ?: src; 730 bool ro = bdrv_is_read_only(to_replace); 731 732 if (ro != bdrv_is_read_only(target_bs)) { 733 bdrv_reopen_set_read_only(target_bs, ro, NULL); 734 } 735 736 /* The mirror job has no requests in flight any more, but we need to 737 * drain potential other users of the BDS before changing the graph. */ 738 assert(s->in_drain); 739 bdrv_drained_begin(target_bs); 740 /* 741 * Cannot use check_to_replace_node() here, because that would 742 * check for an op blocker on @to_replace, and we have our own 743 * there. 744 */ 745 if (bdrv_recurse_can_replace(src, to_replace)) { 746 bdrv_replace_node(to_replace, target_bs, &local_err); 747 } else { 748 error_setg(&local_err, "Can no longer replace '%s' by '%s', " 749 "because it can no longer be guaranteed that doing so " 750 "would not lead to an abrupt change of visible data", 751 to_replace->node_name, target_bs->node_name); 752 } 753 bdrv_drained_end(target_bs); 754 if (local_err) { 755 error_report_err(local_err); 756 ret = -EPERM; 757 } 758 } 759 if (s->to_replace) { 760 bdrv_op_unblock_all(s->to_replace, s->replace_blocker); 761 error_free(s->replace_blocker); 762 bdrv_unref(s->to_replace); 763 } 764 if (replace_aio_context) { 765 aio_context_release(replace_aio_context); 766 } 767 g_free(s->replaces); 768 bdrv_unref(target_bs); 769 770 /* 771 * Remove the mirror filter driver from the graph. Before this, get rid of 772 * the blockers on the intermediate nodes so that the resulting state is 773 * valid. 774 */ 775 block_job_remove_all_bdrv(bjob); 776 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort); 777 778 bs_opaque->job = NULL; 779 780 bdrv_drained_end(src); 781 bdrv_drained_end(mirror_top_bs); 782 s->in_drain = false; 783 bdrv_unref(mirror_top_bs); 784 bdrv_unref(src); 785 786 return ret; 787 } 788 789 static int mirror_prepare(Job *job) 790 { 791 return mirror_exit_common(job); 792 } 793 794 static void mirror_abort(Job *job) 795 { 796 int ret = mirror_exit_common(job); 797 assert(ret == 0); 798 } 799 800 static void coroutine_fn mirror_throttle(MirrorBlockJob *s) 801 { 802 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 803 804 if (now - s->last_pause_ns > BLOCK_JOB_SLICE_TIME) { 805 s->last_pause_ns = now; 806 job_sleep_ns(&s->common.job, 0); 807 } else { 808 job_pause_point(&s->common.job); 809 } 810 } 811 812 static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) 813 { 814 int64_t offset; 815 BlockDriverState *bs = s->mirror_top_bs->backing->bs; 816 BlockDriverState *target_bs = blk_bs(s->target); 817 int ret; 818 int64_t count; 819 820 if (s->zero_target) { 821 if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { 822 bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length); 823 return 0; 824 } 825 826 s->initial_zeroing_ongoing = true; 827 for (offset = 0; offset < s->bdev_length; ) { 828 int bytes = MIN(s->bdev_length - offset, 829 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 830 831 mirror_throttle(s); 832 833 if (job_is_cancelled(&s->common.job)) { 834 s->initial_zeroing_ongoing = false; 835 return 0; 836 } 837 838 if (s->in_flight >= MAX_IN_FLIGHT) { 839 trace_mirror_yield(s, UINT64_MAX, s->buf_free_count, 840 s->in_flight); 841 mirror_wait_for_free_in_flight_slot(s); 842 continue; 843 } 844 845 mirror_perform(s, offset, bytes, MIRROR_METHOD_ZERO); 846 offset += bytes; 847 } 848 849 mirror_wait_for_all_io(s); 850 s->initial_zeroing_ongoing = false; 851 } 852 853 /* First part, loop on the sectors and initialize the dirty bitmap. */ 854 for (offset = 0; offset < s->bdev_length; ) { 855 /* Just to make sure we are not exceeding int limit. */ 856 int bytes = MIN(s->bdev_length - offset, 857 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 858 859 mirror_throttle(s); 860 861 if (job_is_cancelled(&s->common.job)) { 862 return 0; 863 } 864 865 ret = bdrv_is_allocated_above(bs, s->base_overlay, true, offset, bytes, 866 &count); 867 if (ret < 0) { 868 return ret; 869 } 870 871 assert(count); 872 if (ret > 0) { 873 bdrv_set_dirty_bitmap(s->dirty_bitmap, offset, count); 874 } 875 offset += count; 876 } 877 return 0; 878 } 879 880 /* Called when going out of the streaming phase to flush the bulk of the 881 * data to the medium, or just before completing. 882 */ 883 static int mirror_flush(MirrorBlockJob *s) 884 { 885 int ret = blk_flush(s->target); 886 if (ret < 0) { 887 if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) { 888 s->ret = ret; 889 } 890 } 891 return ret; 892 } 893 894 static int coroutine_fn mirror_run(Job *job, Error **errp) 895 { 896 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 897 BlockDriverState *bs = s->mirror_top_bs->backing->bs; 898 BlockDriverState *target_bs = blk_bs(s->target); 899 bool need_drain = true; 900 BlockDeviceIoStatus iostatus; 901 int64_t length; 902 int64_t target_length; 903 BlockDriverInfo bdi; 904 char backing_filename[2]; /* we only need 2 characters because we are only 905 checking for a NULL string */ 906 int ret = 0; 907 908 if (job_is_cancelled(&s->common.job)) { 909 goto immediate_exit; 910 } 911 912 s->bdev_length = bdrv_co_getlength(bs); 913 if (s->bdev_length < 0) { 914 ret = s->bdev_length; 915 goto immediate_exit; 916 } 917 918 target_length = blk_co_getlength(s->target); 919 if (target_length < 0) { 920 ret = target_length; 921 goto immediate_exit; 922 } 923 924 /* Active commit must resize the base image if its size differs from the 925 * active layer. */ 926 if (s->base == blk_bs(s->target)) { 927 if (s->bdev_length > target_length) { 928 ret = blk_co_truncate(s->target, s->bdev_length, false, 929 PREALLOC_MODE_OFF, 0, NULL); 930 if (ret < 0) { 931 goto immediate_exit; 932 } 933 } 934 } else if (s->bdev_length != target_length) { 935 error_setg(errp, "Source and target image have different sizes"); 936 ret = -EINVAL; 937 goto immediate_exit; 938 } 939 940 if (s->bdev_length == 0) { 941 /* Transition to the READY state and wait for complete. */ 942 job_transition_to_ready(&s->common.job); 943 s->actively_synced = true; 944 while (!job_cancel_requested(&s->common.job) && !s->should_complete) { 945 job_yield(&s->common.job); 946 } 947 goto immediate_exit; 948 } 949 950 length = DIV_ROUND_UP(s->bdev_length, s->granularity); 951 s->in_flight_bitmap = bitmap_new(length); 952 953 /* If we have no backing file yet in the destination, we cannot let 954 * the destination do COW. Instead, we copy sectors around the 955 * dirty data if needed. We need a bitmap to do that. 956 */ 957 bdrv_get_backing_filename(target_bs, backing_filename, 958 sizeof(backing_filename)); 959 if (!bdrv_co_get_info(target_bs, &bdi) && bdi.cluster_size) { 960 s->target_cluster_size = bdi.cluster_size; 961 } else { 962 s->target_cluster_size = BDRV_SECTOR_SIZE; 963 } 964 if (backing_filename[0] && !bdrv_backing_chain_next(target_bs) && 965 s->granularity < s->target_cluster_size) { 966 s->buf_size = MAX(s->buf_size, s->target_cluster_size); 967 s->cow_bitmap = bitmap_new(length); 968 } 969 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); 970 971 s->buf = qemu_try_blockalign(bs, s->buf_size); 972 if (s->buf == NULL) { 973 ret = -ENOMEM; 974 goto immediate_exit; 975 } 976 977 mirror_free_init(s); 978 979 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 980 if (!s->is_none_mode) { 981 ret = mirror_dirty_init(s); 982 if (ret < 0 || job_is_cancelled(&s->common.job)) { 983 goto immediate_exit; 984 } 985 } 986 987 assert(!s->dbi); 988 s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap); 989 for (;;) { 990 uint64_t delay_ns = 0; 991 int64_t cnt, delta; 992 bool should_complete; 993 994 if (s->ret < 0) { 995 ret = s->ret; 996 goto immediate_exit; 997 } 998 999 job_pause_point(&s->common.job); 1000 1001 if (job_is_cancelled(&s->common.job)) { 1002 ret = 0; 1003 goto immediate_exit; 1004 } 1005 1006 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1007 /* cnt is the number of dirty bytes remaining and s->bytes_in_flight is 1008 * the number of bytes currently being processed; together those are 1009 * the current remaining operation length */ 1010 job_progress_set_remaining(&s->common.job, 1011 s->bytes_in_flight + cnt + 1012 s->active_write_bytes_in_flight); 1013 1014 /* Note that even when no rate limit is applied we need to yield 1015 * periodically with no pending I/O so that bdrv_drain_all() returns. 1016 * We do so every BLKOCK_JOB_SLICE_TIME nanoseconds, or when there is 1017 * an error, or when the source is clean, whichever comes first. */ 1018 delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns; 1019 WITH_JOB_LOCK_GUARD() { 1020 iostatus = s->common.iostatus; 1021 } 1022 if (delta < BLOCK_JOB_SLICE_TIME && 1023 iostatus == BLOCK_DEVICE_IO_STATUS_OK) { 1024 if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || 1025 (cnt == 0 && s->in_flight > 0)) { 1026 trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight); 1027 mirror_wait_for_free_in_flight_slot(s); 1028 continue; 1029 } else if (cnt != 0) { 1030 delay_ns = mirror_iteration(s); 1031 } 1032 } 1033 1034 should_complete = false; 1035 if (s->in_flight == 0 && cnt == 0) { 1036 trace_mirror_before_flush(s); 1037 if (!job_is_ready(&s->common.job)) { 1038 if (mirror_flush(s) < 0) { 1039 /* Go check s->ret. */ 1040 continue; 1041 } 1042 /* We're out of the streaming phase. From now on, if the job 1043 * is cancelled we will actually complete all pending I/O and 1044 * report completion. This way, block-job-cancel will leave 1045 * the target in a consistent state. 1046 */ 1047 job_transition_to_ready(&s->common.job); 1048 if (s->copy_mode != MIRROR_COPY_MODE_BACKGROUND) { 1049 s->actively_synced = true; 1050 } 1051 } 1052 1053 should_complete = s->should_complete || 1054 job_cancel_requested(&s->common.job); 1055 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1056 } 1057 1058 if (cnt == 0 && should_complete) { 1059 /* The dirty bitmap is not updated while operations are pending. 1060 * If we're about to exit, wait for pending operations before 1061 * calling bdrv_get_dirty_count(bs), or we may exit while the 1062 * source has dirty data to copy! 1063 * 1064 * Note that I/O can be submitted by the guest while 1065 * mirror_populate runs, so pause it now. Before deciding 1066 * whether to switch to target check one last time if I/O has 1067 * come in the meanwhile, and if not flush the data to disk. 1068 */ 1069 trace_mirror_before_drain(s, cnt); 1070 1071 s->in_drain = true; 1072 bdrv_drained_begin(bs); 1073 1074 /* Must be zero because we are drained */ 1075 assert(s->in_active_write_counter == 0); 1076 1077 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1078 if (cnt > 0 || mirror_flush(s) < 0) { 1079 bdrv_drained_end(bs); 1080 s->in_drain = false; 1081 continue; 1082 } 1083 1084 /* The two disks are in sync. Exit and report successful 1085 * completion. 1086 */ 1087 assert(QLIST_EMPTY(&bs->tracked_requests)); 1088 need_drain = false; 1089 break; 1090 } 1091 1092 if (job_is_ready(&s->common.job) && !should_complete) { 1093 delay_ns = (s->in_flight == 0 && 1094 cnt == 0 ? BLOCK_JOB_SLICE_TIME : 0); 1095 } 1096 trace_mirror_before_sleep(s, cnt, job_is_ready(&s->common.job), 1097 delay_ns); 1098 job_sleep_ns(&s->common.job, delay_ns); 1099 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 1100 } 1101 1102 immediate_exit: 1103 if (s->in_flight > 0) { 1104 /* We get here only if something went wrong. Either the job failed, 1105 * or it was cancelled prematurely so that we do not guarantee that 1106 * the target is a copy of the source. 1107 */ 1108 assert(ret < 0 || job_is_cancelled(&s->common.job)); 1109 assert(need_drain); 1110 mirror_wait_for_all_io(s); 1111 } 1112 1113 assert(s->in_flight == 0); 1114 qemu_vfree(s->buf); 1115 g_free(s->cow_bitmap); 1116 g_free(s->in_flight_bitmap); 1117 bdrv_dirty_iter_free(s->dbi); 1118 1119 if (need_drain) { 1120 s->in_drain = true; 1121 bdrv_drained_begin(bs); 1122 } 1123 1124 return ret; 1125 } 1126 1127 static void mirror_complete(Job *job, Error **errp) 1128 { 1129 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1130 1131 if (!job_is_ready(job)) { 1132 error_setg(errp, "The active block job '%s' cannot be completed", 1133 job->id); 1134 return; 1135 } 1136 1137 /* block all operations on to_replace bs */ 1138 if (s->replaces) { 1139 AioContext *replace_aio_context; 1140 1141 s->to_replace = bdrv_find_node(s->replaces); 1142 if (!s->to_replace) { 1143 error_setg(errp, "Node name '%s' not found", s->replaces); 1144 return; 1145 } 1146 1147 replace_aio_context = bdrv_get_aio_context(s->to_replace); 1148 aio_context_acquire(replace_aio_context); 1149 1150 /* TODO Translate this into child freeze system. */ 1151 error_setg(&s->replace_blocker, 1152 "block device is in use by block-job-complete"); 1153 bdrv_op_block_all(s->to_replace, s->replace_blocker); 1154 bdrv_ref(s->to_replace); 1155 1156 aio_context_release(replace_aio_context); 1157 } 1158 1159 s->should_complete = true; 1160 1161 /* If the job is paused, it will be re-entered when it is resumed */ 1162 WITH_JOB_LOCK_GUARD() { 1163 if (!job->paused) { 1164 job_enter_cond_locked(job, NULL); 1165 } 1166 } 1167 } 1168 1169 static void coroutine_fn mirror_pause(Job *job) 1170 { 1171 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1172 1173 mirror_wait_for_all_io(s); 1174 } 1175 1176 static bool mirror_drained_poll(BlockJob *job) 1177 { 1178 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1179 1180 /* If the job isn't paused nor cancelled, we can't be sure that it won't 1181 * issue more requests. We make an exception if we've reached this point 1182 * from one of our own drain sections, to avoid a deadlock waiting for 1183 * ourselves. 1184 */ 1185 WITH_JOB_LOCK_GUARD() { 1186 if (!s->common.job.paused && !job_is_cancelled_locked(&job->job) 1187 && !s->in_drain) { 1188 return true; 1189 } 1190 } 1191 1192 return !!s->in_flight; 1193 } 1194 1195 static bool mirror_cancel(Job *job, bool force) 1196 { 1197 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1198 BlockDriverState *target = blk_bs(s->target); 1199 1200 /* 1201 * Before the job is READY, we treat any cancellation like a 1202 * force-cancellation. 1203 */ 1204 force = force || !job_is_ready(job); 1205 1206 if (force) { 1207 bdrv_cancel_in_flight(target); 1208 } 1209 return force; 1210 } 1211 1212 static bool commit_active_cancel(Job *job, bool force) 1213 { 1214 /* Same as above in mirror_cancel() */ 1215 return force || !job_is_ready(job); 1216 } 1217 1218 static const BlockJobDriver mirror_job_driver = { 1219 .job_driver = { 1220 .instance_size = sizeof(MirrorBlockJob), 1221 .job_type = JOB_TYPE_MIRROR, 1222 .free = block_job_free, 1223 .user_resume = block_job_user_resume, 1224 .run = mirror_run, 1225 .prepare = mirror_prepare, 1226 .abort = mirror_abort, 1227 .pause = mirror_pause, 1228 .complete = mirror_complete, 1229 .cancel = mirror_cancel, 1230 }, 1231 .drained_poll = mirror_drained_poll, 1232 }; 1233 1234 static const BlockJobDriver commit_active_job_driver = { 1235 .job_driver = { 1236 .instance_size = sizeof(MirrorBlockJob), 1237 .job_type = JOB_TYPE_COMMIT, 1238 .free = block_job_free, 1239 .user_resume = block_job_user_resume, 1240 .run = mirror_run, 1241 .prepare = mirror_prepare, 1242 .abort = mirror_abort, 1243 .pause = mirror_pause, 1244 .complete = mirror_complete, 1245 .cancel = commit_active_cancel, 1246 }, 1247 .drained_poll = mirror_drained_poll, 1248 }; 1249 1250 static void coroutine_fn 1251 do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, 1252 uint64_t offset, uint64_t bytes, 1253 QEMUIOVector *qiov, int flags) 1254 { 1255 int ret; 1256 size_t qiov_offset = 0; 1257 int64_t bitmap_offset, bitmap_end; 1258 1259 if (!QEMU_IS_ALIGNED(offset, job->granularity) && 1260 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset)) 1261 { 1262 /* 1263 * Dirty unaligned padding: ignore it. 1264 * 1265 * Reasoning: 1266 * 1. If we copy it, we can't reset corresponding bit in 1267 * dirty_bitmap as there may be some "dirty" bytes still not 1268 * copied. 1269 * 2. It's already dirty, so skipping it we don't diverge mirror 1270 * progress. 1271 * 1272 * Note, that because of this, guest write may have no contribution 1273 * into mirror converge, but that's not bad, as we have background 1274 * process of mirroring. If under some bad circumstances (high guest 1275 * IO load) background process starve, we will not converge anyway, 1276 * even if each write will contribute, as guest is not guaranteed to 1277 * rewrite the whole disk. 1278 */ 1279 qiov_offset = QEMU_ALIGN_UP(offset, job->granularity) - offset; 1280 if (bytes <= qiov_offset) { 1281 /* nothing to do after shrink */ 1282 return; 1283 } 1284 offset += qiov_offset; 1285 bytes -= qiov_offset; 1286 } 1287 1288 if (!QEMU_IS_ALIGNED(offset + bytes, job->granularity) && 1289 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset + bytes - 1)) 1290 { 1291 uint64_t tail = (offset + bytes) % job->granularity; 1292 1293 if (bytes <= tail) { 1294 /* nothing to do after shrink */ 1295 return; 1296 } 1297 bytes -= tail; 1298 } 1299 1300 /* 1301 * Tails are either clean or shrunk, so for bitmap resetting 1302 * we safely align the range down. 1303 */ 1304 bitmap_offset = QEMU_ALIGN_UP(offset, job->granularity); 1305 bitmap_end = QEMU_ALIGN_DOWN(offset + bytes, job->granularity); 1306 if (bitmap_offset < bitmap_end) { 1307 bdrv_reset_dirty_bitmap(job->dirty_bitmap, bitmap_offset, 1308 bitmap_end - bitmap_offset); 1309 } 1310 1311 job_progress_increase_remaining(&job->common.job, bytes); 1312 job->active_write_bytes_in_flight += bytes; 1313 1314 switch (method) { 1315 case MIRROR_METHOD_COPY: 1316 ret = blk_co_pwritev_part(job->target, offset, bytes, 1317 qiov, qiov_offset, flags); 1318 break; 1319 1320 case MIRROR_METHOD_ZERO: 1321 assert(!qiov); 1322 ret = blk_co_pwrite_zeroes(job->target, offset, bytes, flags); 1323 break; 1324 1325 case MIRROR_METHOD_DISCARD: 1326 assert(!qiov); 1327 ret = blk_co_pdiscard(job->target, offset, bytes); 1328 break; 1329 1330 default: 1331 abort(); 1332 } 1333 1334 job->active_write_bytes_in_flight -= bytes; 1335 if (ret >= 0) { 1336 job_progress_update(&job->common.job, bytes); 1337 } else { 1338 BlockErrorAction action; 1339 1340 /* 1341 * We failed, so we should mark dirty the whole area, aligned up. 1342 * Note that we don't care about shrunk tails if any: they were dirty 1343 * at function start, and they must be still dirty, as we've locked 1344 * the region for in-flight op. 1345 */ 1346 bitmap_offset = QEMU_ALIGN_DOWN(offset, job->granularity); 1347 bitmap_end = QEMU_ALIGN_UP(offset + bytes, job->granularity); 1348 bdrv_set_dirty_bitmap(job->dirty_bitmap, bitmap_offset, 1349 bitmap_end - bitmap_offset); 1350 job->actively_synced = false; 1351 1352 action = mirror_error_action(job, false, -ret); 1353 if (action == BLOCK_ERROR_ACTION_REPORT) { 1354 if (!job->ret) { 1355 job->ret = ret; 1356 } 1357 } 1358 } 1359 } 1360 1361 static MirrorOp *coroutine_fn active_write_prepare(MirrorBlockJob *s, 1362 uint64_t offset, 1363 uint64_t bytes) 1364 { 1365 MirrorOp *op; 1366 uint64_t start_chunk = offset / s->granularity; 1367 uint64_t end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 1368 1369 op = g_new(MirrorOp, 1); 1370 *op = (MirrorOp){ 1371 .s = s, 1372 .offset = offset, 1373 .bytes = bytes, 1374 .is_active_write = true, 1375 .is_in_flight = true, 1376 .co = qemu_coroutine_self(), 1377 }; 1378 qemu_co_queue_init(&op->waiting_requests); 1379 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 1380 1381 s->in_active_write_counter++; 1382 1383 /* 1384 * Wait for concurrent requests affecting the area. If there are already 1385 * running requests that are copying off now-to-be stale data in the area, 1386 * we must wait for them to finish before we begin writing fresh data to the 1387 * target so that the write operations appear in the correct order. 1388 * Note that background requests (see mirror_iteration()) in contrast only 1389 * wait for conflicting requests at the start of the dirty area, and then 1390 * (based on the in_flight_bitmap) truncate the area to copy so it will not 1391 * conflict with any requests beyond that. For active writes, however, we 1392 * cannot truncate that area. The request from our parent must be blocked 1393 * until the area is copied in full. Therefore, we must wait for the whole 1394 * area to become free of concurrent requests. 1395 */ 1396 mirror_wait_on_conflicts(op, s, offset, bytes); 1397 1398 bitmap_set(s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1399 1400 return op; 1401 } 1402 1403 static void coroutine_fn active_write_settle(MirrorOp *op) 1404 { 1405 uint64_t start_chunk = op->offset / op->s->granularity; 1406 uint64_t end_chunk = DIV_ROUND_UP(op->offset + op->bytes, 1407 op->s->granularity); 1408 1409 if (!--op->s->in_active_write_counter && op->s->actively_synced) { 1410 BdrvChild *source = op->s->mirror_top_bs->backing; 1411 1412 if (QLIST_FIRST(&source->bs->parents) == source && 1413 QLIST_NEXT(source, next_parent) == NULL) 1414 { 1415 /* Assert that we are back in sync once all active write 1416 * operations are settled. 1417 * Note that we can only assert this if the mirror node 1418 * is the source node's only parent. */ 1419 assert(!bdrv_get_dirty_count(op->s->dirty_bitmap)); 1420 } 1421 } 1422 bitmap_clear(op->s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1423 QTAILQ_REMOVE(&op->s->ops_in_flight, op, next); 1424 qemu_co_queue_restart_all(&op->waiting_requests); 1425 g_free(op); 1426 } 1427 1428 static int coroutine_fn bdrv_mirror_top_preadv(BlockDriverState *bs, 1429 int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags) 1430 { 1431 return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); 1432 } 1433 1434 static int coroutine_fn bdrv_mirror_top_do_write(BlockDriverState *bs, 1435 MirrorMethod method, uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, 1436 int flags) 1437 { 1438 MirrorOp *op = NULL; 1439 MirrorBDSOpaque *s = bs->opaque; 1440 int ret = 0; 1441 bool copy_to_target = false; 1442 1443 if (s->job) { 1444 copy_to_target = s->job->ret >= 0 && 1445 !job_is_cancelled(&s->job->common.job) && 1446 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING; 1447 } 1448 1449 if (copy_to_target) { 1450 op = active_write_prepare(s->job, offset, bytes); 1451 } 1452 1453 switch (method) { 1454 case MIRROR_METHOD_COPY: 1455 ret = bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags); 1456 break; 1457 1458 case MIRROR_METHOD_ZERO: 1459 ret = bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags); 1460 break; 1461 1462 case MIRROR_METHOD_DISCARD: 1463 ret = bdrv_co_pdiscard(bs->backing, offset, bytes); 1464 break; 1465 1466 default: 1467 abort(); 1468 } 1469 1470 if (ret < 0) { 1471 goto out; 1472 } 1473 1474 if (copy_to_target) { 1475 do_sync_target_write(s->job, method, offset, bytes, qiov, flags); 1476 } 1477 1478 out: 1479 if (copy_to_target) { 1480 active_write_settle(op); 1481 } 1482 return ret; 1483 } 1484 1485 static int coroutine_fn bdrv_mirror_top_pwritev(BlockDriverState *bs, 1486 int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags) 1487 { 1488 MirrorBDSOpaque *s = bs->opaque; 1489 QEMUIOVector bounce_qiov; 1490 void *bounce_buf; 1491 int ret = 0; 1492 bool copy_to_target = false; 1493 1494 if (s->job) { 1495 copy_to_target = s->job->ret >= 0 && 1496 !job_is_cancelled(&s->job->common.job) && 1497 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING; 1498 } 1499 1500 if (copy_to_target) { 1501 /* The guest might concurrently modify the data to write; but 1502 * the data on source and destination must match, so we have 1503 * to use a bounce buffer if we are going to write to the 1504 * target now. */ 1505 bounce_buf = qemu_blockalign(bs, bytes); 1506 iov_to_buf_full(qiov->iov, qiov->niov, 0, bounce_buf, bytes); 1507 1508 qemu_iovec_init(&bounce_qiov, 1); 1509 qemu_iovec_add(&bounce_qiov, bounce_buf, bytes); 1510 qiov = &bounce_qiov; 1511 1512 flags &= ~BDRV_REQ_REGISTERED_BUF; 1513 } 1514 1515 ret = bdrv_mirror_top_do_write(bs, MIRROR_METHOD_COPY, offset, bytes, qiov, 1516 flags); 1517 1518 if (copy_to_target) { 1519 qemu_iovec_destroy(&bounce_qiov); 1520 qemu_vfree(bounce_buf); 1521 } 1522 1523 return ret; 1524 } 1525 1526 static int coroutine_fn bdrv_mirror_top_flush(BlockDriverState *bs) 1527 { 1528 if (bs->backing == NULL) { 1529 /* we can be here after failed bdrv_append in mirror_start_job */ 1530 return 0; 1531 } 1532 return bdrv_co_flush(bs->backing->bs); 1533 } 1534 1535 static int coroutine_fn bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs, 1536 int64_t offset, int64_t bytes, BdrvRequestFlags flags) 1537 { 1538 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_ZERO, offset, bytes, NULL, 1539 flags); 1540 } 1541 1542 static int coroutine_fn bdrv_mirror_top_pdiscard(BlockDriverState *bs, 1543 int64_t offset, int64_t bytes) 1544 { 1545 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_DISCARD, offset, bytes, 1546 NULL, 0); 1547 } 1548 1549 static void bdrv_mirror_top_refresh_filename(BlockDriverState *bs) 1550 { 1551 if (bs->backing == NULL) { 1552 /* we can be here after failed bdrv_attach_child in 1553 * bdrv_set_backing_hd */ 1554 return; 1555 } 1556 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), 1557 bs->backing->bs->filename); 1558 } 1559 1560 static void bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c, 1561 BdrvChildRole role, 1562 BlockReopenQueue *reopen_queue, 1563 uint64_t perm, uint64_t shared, 1564 uint64_t *nperm, uint64_t *nshared) 1565 { 1566 MirrorBDSOpaque *s = bs->opaque; 1567 1568 if (s->stop) { 1569 /* 1570 * If the job is to be stopped, we do not need to forward 1571 * anything to the real image. 1572 */ 1573 *nperm = 0; 1574 *nshared = BLK_PERM_ALL; 1575 return; 1576 } 1577 1578 bdrv_default_perms(bs, c, role, reopen_queue, 1579 perm, shared, nperm, nshared); 1580 1581 if (s->is_commit) { 1582 /* 1583 * For commit jobs, we cannot take CONSISTENT_READ, because 1584 * that permission is unshared for everything above the base 1585 * node (except for filters on the base node). 1586 * We also have to force-share the WRITE permission, or 1587 * otherwise we would block ourselves at the base node (if 1588 * writes are blocked for a node, they are also blocked for 1589 * its backing file). 1590 * (We could also share RESIZE, because it may be needed for 1591 * the target if its size is less than the top node's; but 1592 * bdrv_default_perms_for_cow() automatically shares RESIZE 1593 * for backing nodes if WRITE is shared, so there is no need 1594 * to do it here.) 1595 */ 1596 *nperm &= ~BLK_PERM_CONSISTENT_READ; 1597 *nshared |= BLK_PERM_WRITE; 1598 } 1599 } 1600 1601 /* Dummy node that provides consistent read to its users without requiring it 1602 * from its backing file and that allows writes on the backing file chain. */ 1603 static BlockDriver bdrv_mirror_top = { 1604 .format_name = "mirror_top", 1605 .bdrv_co_preadv = bdrv_mirror_top_preadv, 1606 .bdrv_co_pwritev = bdrv_mirror_top_pwritev, 1607 .bdrv_co_pwrite_zeroes = bdrv_mirror_top_pwrite_zeroes, 1608 .bdrv_co_pdiscard = bdrv_mirror_top_pdiscard, 1609 .bdrv_co_flush = bdrv_mirror_top_flush, 1610 .bdrv_refresh_filename = bdrv_mirror_top_refresh_filename, 1611 .bdrv_child_perm = bdrv_mirror_top_child_perm, 1612 1613 .is_filter = true, 1614 .filtered_child_is_backing = true, 1615 }; 1616 1617 static BlockJob *mirror_start_job( 1618 const char *job_id, BlockDriverState *bs, 1619 int creation_flags, BlockDriverState *target, 1620 const char *replaces, int64_t speed, 1621 uint32_t granularity, int64_t buf_size, 1622 BlockMirrorBackingMode backing_mode, 1623 bool zero_target, 1624 BlockdevOnError on_source_error, 1625 BlockdevOnError on_target_error, 1626 bool unmap, 1627 BlockCompletionFunc *cb, 1628 void *opaque, 1629 const BlockJobDriver *driver, 1630 bool is_none_mode, BlockDriverState *base, 1631 bool auto_complete, const char *filter_node_name, 1632 bool is_mirror, MirrorCopyMode copy_mode, 1633 Error **errp) 1634 { 1635 MirrorBlockJob *s; 1636 MirrorBDSOpaque *bs_opaque; 1637 BlockDriverState *mirror_top_bs; 1638 bool target_is_backing; 1639 uint64_t target_perms, target_shared_perms; 1640 int ret; 1641 1642 if (granularity == 0) { 1643 granularity = bdrv_get_default_bitmap_granularity(target); 1644 } 1645 1646 assert(is_power_of_2(granularity)); 1647 1648 if (buf_size < 0) { 1649 error_setg(errp, "Invalid parameter 'buf-size'"); 1650 return NULL; 1651 } 1652 1653 if (buf_size == 0) { 1654 buf_size = DEFAULT_MIRROR_BUF_SIZE; 1655 } 1656 1657 if (bdrv_skip_filters(bs) == bdrv_skip_filters(target)) { 1658 error_setg(errp, "Can't mirror node into itself"); 1659 return NULL; 1660 } 1661 1662 target_is_backing = bdrv_chain_contains(bs, target); 1663 1664 /* In the case of active commit, add dummy driver to provide consistent 1665 * reads on the top, while disabling it in the intermediate nodes, and make 1666 * the backing chain writable. */ 1667 mirror_top_bs = bdrv_new_open_driver(&bdrv_mirror_top, filter_node_name, 1668 BDRV_O_RDWR, errp); 1669 if (mirror_top_bs == NULL) { 1670 return NULL; 1671 } 1672 if (!filter_node_name) { 1673 mirror_top_bs->implicit = true; 1674 } 1675 1676 /* So that we can always drop this node */ 1677 mirror_top_bs->never_freeze = true; 1678 1679 mirror_top_bs->total_sectors = bs->total_sectors; 1680 mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED; 1681 mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED | 1682 BDRV_REQ_NO_FALLBACK; 1683 bs_opaque = g_new0(MirrorBDSOpaque, 1); 1684 mirror_top_bs->opaque = bs_opaque; 1685 1686 bs_opaque->is_commit = target_is_backing; 1687 1688 bdrv_drained_begin(bs); 1689 ret = bdrv_append(mirror_top_bs, bs, errp); 1690 bdrv_drained_end(bs); 1691 1692 if (ret < 0) { 1693 bdrv_unref(mirror_top_bs); 1694 return NULL; 1695 } 1696 1697 /* Make sure that the source is not resized while the job is running */ 1698 s = block_job_create(job_id, driver, NULL, mirror_top_bs, 1699 BLK_PERM_CONSISTENT_READ, 1700 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | 1701 BLK_PERM_WRITE, speed, 1702 creation_flags, cb, opaque, errp); 1703 if (!s) { 1704 goto fail; 1705 } 1706 bs_opaque->job = s; 1707 1708 /* The block job now has a reference to this node */ 1709 bdrv_unref(mirror_top_bs); 1710 1711 s->mirror_top_bs = mirror_top_bs; 1712 1713 /* No resize for the target either; while the mirror is still running, a 1714 * consistent read isn't necessarily possible. We could possibly allow 1715 * writes and graph modifications, though it would likely defeat the 1716 * purpose of a mirror, so leave them blocked for now. 1717 * 1718 * In the case of active commit, things look a bit different, though, 1719 * because the target is an already populated backing file in active use. 1720 * We can allow anything except resize there.*/ 1721 1722 target_perms = BLK_PERM_WRITE; 1723 target_shared_perms = BLK_PERM_WRITE_UNCHANGED; 1724 1725 if (target_is_backing) { 1726 int64_t bs_size, target_size; 1727 bs_size = bdrv_getlength(bs); 1728 if (bs_size < 0) { 1729 error_setg_errno(errp, -bs_size, 1730 "Could not inquire top image size"); 1731 goto fail; 1732 } 1733 1734 target_size = bdrv_getlength(target); 1735 if (target_size < 0) { 1736 error_setg_errno(errp, -target_size, 1737 "Could not inquire base image size"); 1738 goto fail; 1739 } 1740 1741 if (target_size < bs_size) { 1742 target_perms |= BLK_PERM_RESIZE; 1743 } 1744 1745 target_shared_perms |= BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE; 1746 } else if (bdrv_chain_contains(bs, bdrv_skip_filters(target))) { 1747 /* 1748 * We may want to allow this in the future, but it would 1749 * require taking some extra care. 1750 */ 1751 error_setg(errp, "Cannot mirror to a filter on top of a node in the " 1752 "source's backing chain"); 1753 goto fail; 1754 } 1755 1756 s->target = blk_new(s->common.job.aio_context, 1757 target_perms, target_shared_perms); 1758 ret = blk_insert_bs(s->target, target, errp); 1759 if (ret < 0) { 1760 goto fail; 1761 } 1762 if (is_mirror) { 1763 /* XXX: Mirror target could be a NBD server of target QEMU in the case 1764 * of non-shared block migration. To allow migration completion, we 1765 * have to allow "inactivate" of the target BB. When that happens, we 1766 * know the job is drained, and the vcpus are stopped, so no write 1767 * operation will be performed. Block layer already has assertions to 1768 * ensure that. */ 1769 blk_set_force_allow_inactivate(s->target); 1770 } 1771 blk_set_allow_aio_context_change(s->target, true); 1772 blk_set_disable_request_queuing(s->target, true); 1773 1774 s->replaces = g_strdup(replaces); 1775 s->on_source_error = on_source_error; 1776 s->on_target_error = on_target_error; 1777 s->is_none_mode = is_none_mode; 1778 s->backing_mode = backing_mode; 1779 s->zero_target = zero_target; 1780 s->copy_mode = copy_mode; 1781 s->base = base; 1782 s->base_overlay = bdrv_find_overlay(bs, base); 1783 s->granularity = granularity; 1784 s->buf_size = ROUND_UP(buf_size, granularity); 1785 s->unmap = unmap; 1786 if (auto_complete) { 1787 s->should_complete = true; 1788 } 1789 1790 s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp); 1791 if (!s->dirty_bitmap) { 1792 goto fail; 1793 } 1794 if (s->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING) { 1795 bdrv_disable_dirty_bitmap(s->dirty_bitmap); 1796 } 1797 1798 ret = block_job_add_bdrv(&s->common, "source", bs, 0, 1799 BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE | 1800 BLK_PERM_CONSISTENT_READ, 1801 errp); 1802 if (ret < 0) { 1803 goto fail; 1804 } 1805 1806 /* Required permissions are already taken with blk_new() */ 1807 block_job_add_bdrv(&s->common, "target", target, 0, BLK_PERM_ALL, 1808 &error_abort); 1809 1810 /* In commit_active_start() all intermediate nodes disappear, so 1811 * any jobs in them must be blocked */ 1812 if (target_is_backing) { 1813 BlockDriverState *iter, *filtered_target; 1814 uint64_t iter_shared_perms; 1815 1816 /* 1817 * The topmost node with 1818 * bdrv_skip_filters(filtered_target) == bdrv_skip_filters(target) 1819 */ 1820 filtered_target = bdrv_cow_bs(bdrv_find_overlay(bs, target)); 1821 1822 assert(bdrv_skip_filters(filtered_target) == 1823 bdrv_skip_filters(target)); 1824 1825 /* 1826 * XXX BLK_PERM_WRITE needs to be allowed so we don't block 1827 * ourselves at s->base (if writes are blocked for a node, they are 1828 * also blocked for its backing file). The other options would be a 1829 * second filter driver above s->base (== target). 1830 */ 1831 iter_shared_perms = BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE; 1832 1833 for (iter = bdrv_filter_or_cow_bs(bs); iter != target; 1834 iter = bdrv_filter_or_cow_bs(iter)) 1835 { 1836 if (iter == filtered_target) { 1837 /* 1838 * From here on, all nodes are filters on the base. 1839 * This allows us to share BLK_PERM_CONSISTENT_READ. 1840 */ 1841 iter_shared_perms |= BLK_PERM_CONSISTENT_READ; 1842 } 1843 1844 ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, 1845 iter_shared_perms, errp); 1846 if (ret < 0) { 1847 goto fail; 1848 } 1849 } 1850 1851 if (bdrv_freeze_backing_chain(mirror_top_bs, target, errp) < 0) { 1852 goto fail; 1853 } 1854 } 1855 1856 QTAILQ_INIT(&s->ops_in_flight); 1857 1858 trace_mirror_start(bs, s, opaque); 1859 job_start(&s->common.job); 1860 1861 return &s->common; 1862 1863 fail: 1864 if (s) { 1865 /* Make sure this BDS does not go away until we have completed the graph 1866 * changes below */ 1867 bdrv_ref(mirror_top_bs); 1868 1869 g_free(s->replaces); 1870 blk_unref(s->target); 1871 bs_opaque->job = NULL; 1872 if (s->dirty_bitmap) { 1873 bdrv_release_dirty_bitmap(s->dirty_bitmap); 1874 } 1875 job_early_fail(&s->common.job); 1876 } 1877 1878 bs_opaque->stop = true; 1879 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 1880 &error_abort); 1881 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort); 1882 1883 bdrv_unref(mirror_top_bs); 1884 1885 return NULL; 1886 } 1887 1888 void mirror_start(const char *job_id, BlockDriverState *bs, 1889 BlockDriverState *target, const char *replaces, 1890 int creation_flags, int64_t speed, 1891 uint32_t granularity, int64_t buf_size, 1892 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, 1893 bool zero_target, 1894 BlockdevOnError on_source_error, 1895 BlockdevOnError on_target_error, 1896 bool unmap, const char *filter_node_name, 1897 MirrorCopyMode copy_mode, Error **errp) 1898 { 1899 bool is_none_mode; 1900 BlockDriverState *base; 1901 1902 GLOBAL_STATE_CODE(); 1903 1904 if ((mode == MIRROR_SYNC_MODE_INCREMENTAL) || 1905 (mode == MIRROR_SYNC_MODE_BITMAP)) { 1906 error_setg(errp, "Sync mode '%s' not supported", 1907 MirrorSyncMode_str(mode)); 1908 return; 1909 } 1910 is_none_mode = mode == MIRROR_SYNC_MODE_NONE; 1911 base = mode == MIRROR_SYNC_MODE_TOP ? bdrv_backing_chain_next(bs) : NULL; 1912 mirror_start_job(job_id, bs, creation_flags, target, replaces, 1913 speed, granularity, buf_size, backing_mode, zero_target, 1914 on_source_error, on_target_error, unmap, NULL, NULL, 1915 &mirror_job_driver, is_none_mode, base, false, 1916 filter_node_name, true, copy_mode, errp); 1917 } 1918 1919 BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs, 1920 BlockDriverState *base, int creation_flags, 1921 int64_t speed, BlockdevOnError on_error, 1922 const char *filter_node_name, 1923 BlockCompletionFunc *cb, void *opaque, 1924 bool auto_complete, Error **errp) 1925 { 1926 bool base_read_only; 1927 BlockJob *job; 1928 1929 GLOBAL_STATE_CODE(); 1930 1931 base_read_only = bdrv_is_read_only(base); 1932 1933 if (base_read_only) { 1934 if (bdrv_reopen_set_read_only(base, false, errp) < 0) { 1935 return NULL; 1936 } 1937 } 1938 1939 job = mirror_start_job( 1940 job_id, bs, creation_flags, base, NULL, speed, 0, 0, 1941 MIRROR_LEAVE_BACKING_CHAIN, false, 1942 on_error, on_error, true, cb, opaque, 1943 &commit_active_job_driver, false, base, auto_complete, 1944 filter_node_name, false, MIRROR_COPY_MODE_BACKGROUND, 1945 errp); 1946 if (!job) { 1947 goto error_restore_flags; 1948 } 1949 1950 return job; 1951 1952 error_restore_flags: 1953 /* ignore error and errp for bdrv_reopen, because we want to propagate 1954 * the original error */ 1955 if (base_read_only) { 1956 bdrv_reopen_set_read_only(base, true, NULL); 1957 } 1958 return NULL; 1959 } 1960