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 "qapi/qmp/qerror.h" 25 #include "qemu/ratelimit.h" 26 #include "qemu/bitmap.h" 27 #include "qemu/memalign.h" 28 29 #define MAX_IN_FLIGHT 16 30 #define MAX_IO_BYTES (1 << 20) /* 1 Mb */ 31 #define DEFAULT_MIRROR_BUF_SIZE (MAX_IN_FLIGHT * MAX_IO_BYTES) 32 33 /* The mirroring buffer is a list of granularity-sized chunks. 34 * Free chunks are organized in a list. 35 */ 36 typedef struct MirrorBuffer { 37 QSIMPLEQ_ENTRY(MirrorBuffer) next; 38 } MirrorBuffer; 39 40 typedef struct MirrorOp MirrorOp; 41 42 typedef struct MirrorBlockJob { 43 BlockJob common; 44 BlockBackend *target; 45 BlockDriverState *mirror_top_bs; 46 BlockDriverState *base; 47 BlockDriverState *base_overlay; 48 49 /* The name of the graph node to replace */ 50 char *replaces; 51 /* The BDS to replace */ 52 BlockDriverState *to_replace; 53 /* Used to block operations on the drive-mirror-replace target */ 54 Error *replace_blocker; 55 bool is_none_mode; 56 BlockMirrorBackingMode backing_mode; 57 /* Whether the target image requires explicit zero-initialization */ 58 bool zero_target; 59 MirrorCopyMode copy_mode; 60 BlockdevOnError on_source_error, on_target_error; 61 /* Set when the target is synced (dirty bitmap is clean, nothing 62 * in flight) and the job is running in active mode */ 63 bool actively_synced; 64 bool should_complete; 65 int64_t granularity; 66 size_t buf_size; 67 int64_t bdev_length; 68 unsigned long *cow_bitmap; 69 BdrvDirtyBitmap *dirty_bitmap; 70 BdrvDirtyBitmapIter *dbi; 71 uint8_t *buf; 72 QSIMPLEQ_HEAD(, MirrorBuffer) buf_free; 73 int buf_free_count; 74 75 uint64_t last_pause_ns; 76 unsigned long *in_flight_bitmap; 77 unsigned in_flight; 78 int64_t bytes_in_flight; 79 QTAILQ_HEAD(, MirrorOp) ops_in_flight; 80 int ret; 81 bool unmap; 82 int target_cluster_size; 83 int max_iov; 84 bool initial_zeroing_ongoing; 85 int in_active_write_counter; 86 int64_t active_write_bytes_in_flight; 87 bool prepared; 88 bool in_drain; 89 } MirrorBlockJob; 90 91 typedef struct MirrorBDSOpaque { 92 MirrorBlockJob *job; 93 bool stop; 94 bool is_commit; 95 } MirrorBDSOpaque; 96 97 struct MirrorOp { 98 MirrorBlockJob *s; 99 QEMUIOVector qiov; 100 int64_t offset; 101 uint64_t bytes; 102 103 /* The pointee is set by mirror_co_read(), mirror_co_zero(), and 104 * mirror_co_discard() before yielding for the first time */ 105 int64_t *bytes_handled; 106 107 bool is_pseudo_op; 108 bool is_active_write; 109 bool is_in_flight; 110 CoQueue waiting_requests; 111 Coroutine *co; 112 MirrorOp *waiting_for_op; 113 114 QTAILQ_ENTRY(MirrorOp) next; 115 }; 116 117 typedef enum MirrorMethod { 118 MIRROR_METHOD_COPY, 119 MIRROR_METHOD_ZERO, 120 MIRROR_METHOD_DISCARD, 121 } MirrorMethod; 122 123 static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, 124 int error) 125 { 126 s->actively_synced = false; 127 if (read) { 128 return block_job_error_action(&s->common, s->on_source_error, 129 true, error); 130 } else { 131 return block_job_error_action(&s->common, s->on_target_error, 132 false, error); 133 } 134 } 135 136 static void coroutine_fn mirror_wait_on_conflicts(MirrorOp *self, 137 MirrorBlockJob *s, 138 uint64_t offset, 139 uint64_t bytes) 140 { 141 uint64_t self_start_chunk = offset / s->granularity; 142 uint64_t self_end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 143 uint64_t self_nb_chunks = self_end_chunk - self_start_chunk; 144 145 while (find_next_bit(s->in_flight_bitmap, self_end_chunk, 146 self_start_chunk) < self_end_chunk && 147 s->ret >= 0) 148 { 149 MirrorOp *op; 150 151 QTAILQ_FOREACH(op, &s->ops_in_flight, next) { 152 uint64_t op_start_chunk = op->offset / s->granularity; 153 uint64_t op_nb_chunks = DIV_ROUND_UP(op->offset + op->bytes, 154 s->granularity) - 155 op_start_chunk; 156 157 if (op == self) { 158 continue; 159 } 160 161 if (ranges_overlap(self_start_chunk, self_nb_chunks, 162 op_start_chunk, op_nb_chunks)) 163 { 164 if (self) { 165 /* 166 * If the operation is already (indirectly) waiting for us, 167 * or will wait for us as soon as it wakes up, then just go 168 * on (instead of producing a deadlock in the former case). 169 */ 170 if (op->waiting_for_op) { 171 continue; 172 } 173 174 self->waiting_for_op = op; 175 } 176 177 qemu_co_queue_wait(&op->waiting_requests, NULL); 178 179 if (self) { 180 self->waiting_for_op = NULL; 181 } 182 183 break; 184 } 185 } 186 } 187 } 188 189 static void coroutine_fn mirror_iteration_done(MirrorOp *op, int ret) 190 { 191 MirrorBlockJob *s = op->s; 192 struct iovec *iov; 193 int64_t chunk_num; 194 int i, nb_chunks; 195 196 trace_mirror_iteration_done(s, op->offset, op->bytes, ret); 197 198 s->in_flight--; 199 s->bytes_in_flight -= op->bytes; 200 iov = op->qiov.iov; 201 for (i = 0; i < op->qiov.niov; i++) { 202 MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base; 203 QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next); 204 s->buf_free_count++; 205 } 206 207 chunk_num = op->offset / s->granularity; 208 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity); 209 210 bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks); 211 QTAILQ_REMOVE(&s->ops_in_flight, op, next); 212 if (ret >= 0) { 213 if (s->cow_bitmap) { 214 bitmap_set(s->cow_bitmap, chunk_num, nb_chunks); 215 } 216 if (!s->initial_zeroing_ongoing) { 217 job_progress_update(&s->common.job, op->bytes); 218 } 219 } 220 qemu_iovec_destroy(&op->qiov); 221 222 qemu_co_queue_restart_all(&op->waiting_requests); 223 g_free(op); 224 } 225 226 static void coroutine_fn mirror_write_complete(MirrorOp *op, int ret) 227 { 228 MirrorBlockJob *s = op->s; 229 230 if (ret < 0) { 231 BlockErrorAction action; 232 233 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes); 234 action = mirror_error_action(s, false, -ret); 235 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 236 s->ret = ret; 237 } 238 } 239 240 mirror_iteration_done(op, ret); 241 } 242 243 static void coroutine_fn mirror_read_complete(MirrorOp *op, int ret) 244 { 245 MirrorBlockJob *s = op->s; 246 247 if (ret < 0) { 248 BlockErrorAction action; 249 250 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes); 251 action = mirror_error_action(s, true, -ret); 252 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 253 s->ret = ret; 254 } 255 256 mirror_iteration_done(op, ret); 257 return; 258 } 259 260 ret = blk_co_pwritev(s->target, op->offset, op->qiov.size, &op->qiov, 0); 261 mirror_write_complete(op, ret); 262 } 263 264 /* Clip bytes relative to offset to not exceed end-of-file */ 265 static inline int64_t mirror_clip_bytes(MirrorBlockJob *s, 266 int64_t offset, 267 int64_t bytes) 268 { 269 return MIN(bytes, s->bdev_length - offset); 270 } 271 272 /* Round offset and/or bytes to target cluster if COW is needed, and 273 * return the offset of the adjusted tail against original. */ 274 static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset, 275 uint64_t *bytes) 276 { 277 bool need_cow; 278 int ret = 0; 279 int64_t align_offset = *offset; 280 int64_t align_bytes = *bytes; 281 int max_bytes = s->granularity * s->max_iov; 282 283 need_cow = !test_bit(*offset / s->granularity, s->cow_bitmap); 284 need_cow |= !test_bit((*offset + *bytes - 1) / s->granularity, 285 s->cow_bitmap); 286 if (need_cow) { 287 bdrv_round_to_clusters(blk_bs(s->target), *offset, *bytes, 288 &align_offset, &align_bytes); 289 } 290 291 if (align_bytes > max_bytes) { 292 align_bytes = max_bytes; 293 if (need_cow) { 294 align_bytes = QEMU_ALIGN_DOWN(align_bytes, s->target_cluster_size); 295 } 296 } 297 /* Clipping may result in align_bytes unaligned to chunk boundary, but 298 * that doesn't matter because it's already the end of source image. */ 299 align_bytes = mirror_clip_bytes(s, align_offset, align_bytes); 300 301 ret = align_offset + align_bytes - (*offset + *bytes); 302 *offset = align_offset; 303 *bytes = align_bytes; 304 assert(ret >= 0); 305 return ret; 306 } 307 308 static inline void coroutine_fn 309 mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s) 310 { 311 MirrorOp *op; 312 313 QTAILQ_FOREACH(op, &s->ops_in_flight, next) { 314 /* 315 * Do not wait on pseudo ops, because it may in turn wait on 316 * some other operation to start, which may in fact be the 317 * caller of this function. Since there is only one pseudo op 318 * at any given time, we will always find some real operation 319 * to wait on. 320 * Also, do not wait on active operations, because they do not 321 * use up in-flight slots. 322 */ 323 if (!op->is_pseudo_op && op->is_in_flight && !op->is_active_write) { 324 qemu_co_queue_wait(&op->waiting_requests, NULL); 325 return; 326 } 327 } 328 abort(); 329 } 330 331 /* Perform a mirror copy operation. 332 * 333 * *op->bytes_handled is set to the number of bytes copied after and 334 * including offset, excluding any bytes copied prior to offset due 335 * to alignment. This will be op->bytes if no alignment is necessary, 336 * or (new_end - op->offset) if the tail is rounded up or down due to 337 * alignment or buffer limit. 338 */ 339 static void coroutine_fn mirror_co_read(void *opaque) 340 { 341 MirrorOp *op = opaque; 342 MirrorBlockJob *s = op->s; 343 int nb_chunks; 344 uint64_t ret; 345 uint64_t max_bytes; 346 347 max_bytes = s->granularity * s->max_iov; 348 349 /* We can only handle as much as buf_size at a time. */ 350 op->bytes = MIN(s->buf_size, MIN(max_bytes, op->bytes)); 351 assert(op->bytes); 352 assert(op->bytes < BDRV_REQUEST_MAX_BYTES); 353 *op->bytes_handled = op->bytes; 354 355 if (s->cow_bitmap) { 356 *op->bytes_handled += mirror_cow_align(s, &op->offset, &op->bytes); 357 } 358 /* Cannot exceed BDRV_REQUEST_MAX_BYTES + INT_MAX */ 359 assert(*op->bytes_handled <= UINT_MAX); 360 assert(op->bytes <= s->buf_size); 361 /* The offset is granularity-aligned because: 362 * 1) Caller passes in aligned values; 363 * 2) mirror_cow_align is used only when target cluster is larger. */ 364 assert(QEMU_IS_ALIGNED(op->offset, s->granularity)); 365 /* The range is sector-aligned, since bdrv_getlength() rounds up. */ 366 assert(QEMU_IS_ALIGNED(op->bytes, BDRV_SECTOR_SIZE)); 367 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity); 368 369 while (s->buf_free_count < nb_chunks) { 370 trace_mirror_yield_in_flight(s, op->offset, s->in_flight); 371 mirror_wait_for_free_in_flight_slot(s); 372 } 373 374 /* Now make a QEMUIOVector taking enough granularity-sized chunks 375 * from s->buf_free. 376 */ 377 qemu_iovec_init(&op->qiov, nb_chunks); 378 while (nb_chunks-- > 0) { 379 MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free); 380 size_t remaining = op->bytes - op->qiov.size; 381 382 QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next); 383 s->buf_free_count--; 384 qemu_iovec_add(&op->qiov, buf, MIN(s->granularity, remaining)); 385 } 386 387 /* Copy the dirty cluster. */ 388 s->in_flight++; 389 s->bytes_in_flight += op->bytes; 390 op->is_in_flight = true; 391 trace_mirror_one_iteration(s, op->offset, op->bytes); 392 393 ret = bdrv_co_preadv(s->mirror_top_bs->backing, op->offset, op->bytes, 394 &op->qiov, 0); 395 mirror_read_complete(op, ret); 396 } 397 398 static void coroutine_fn mirror_co_zero(void *opaque) 399 { 400 MirrorOp *op = opaque; 401 int ret; 402 403 op->s->in_flight++; 404 op->s->bytes_in_flight += op->bytes; 405 *op->bytes_handled = op->bytes; 406 op->is_in_flight = true; 407 408 ret = blk_co_pwrite_zeroes(op->s->target, op->offset, op->bytes, 409 op->s->unmap ? BDRV_REQ_MAY_UNMAP : 0); 410 mirror_write_complete(op, ret); 411 } 412 413 static void coroutine_fn mirror_co_discard(void *opaque) 414 { 415 MirrorOp *op = opaque; 416 int ret; 417 418 op->s->in_flight++; 419 op->s->bytes_in_flight += op->bytes; 420 *op->bytes_handled = op->bytes; 421 op->is_in_flight = true; 422 423 ret = blk_co_pdiscard(op->s->target, op->offset, op->bytes); 424 mirror_write_complete(op, ret); 425 } 426 427 static unsigned mirror_perform(MirrorBlockJob *s, int64_t offset, 428 unsigned bytes, MirrorMethod mirror_method) 429 { 430 MirrorOp *op; 431 Coroutine *co; 432 int64_t bytes_handled = -1; 433 434 op = g_new(MirrorOp, 1); 435 *op = (MirrorOp){ 436 .s = s, 437 .offset = offset, 438 .bytes = bytes, 439 .bytes_handled = &bytes_handled, 440 }; 441 qemu_co_queue_init(&op->waiting_requests); 442 443 switch (mirror_method) { 444 case MIRROR_METHOD_COPY: 445 co = qemu_coroutine_create(mirror_co_read, op); 446 break; 447 case MIRROR_METHOD_ZERO: 448 co = qemu_coroutine_create(mirror_co_zero, op); 449 break; 450 case MIRROR_METHOD_DISCARD: 451 co = qemu_coroutine_create(mirror_co_discard, op); 452 break; 453 default: 454 abort(); 455 } 456 op->co = co; 457 458 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 459 qemu_coroutine_enter(co); 460 /* At this point, ownership of op has been moved to the coroutine 461 * and the object may already be freed */ 462 463 /* Assert that this value has been set */ 464 assert(bytes_handled >= 0); 465 466 /* Same assertion as in mirror_co_read() (and for mirror_co_read() 467 * and mirror_co_discard(), bytes_handled == op->bytes, which 468 * is the @bytes parameter given to this function) */ 469 assert(bytes_handled <= UINT_MAX); 470 return bytes_handled; 471 } 472 473 static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) 474 { 475 BlockDriverState *source = s->mirror_top_bs->backing->bs; 476 MirrorOp *pseudo_op; 477 int64_t offset; 478 uint64_t delay_ns = 0, ret = 0; 479 /* At least the first dirty chunk is mirrored in one iteration. */ 480 int nb_chunks = 1; 481 bool write_zeroes_ok = bdrv_can_write_zeroes_with_unmap(blk_bs(s->target)); 482 int max_io_bytes = MAX(s->buf_size / MAX_IN_FLIGHT, MAX_IO_BYTES); 483 484 bdrv_dirty_bitmap_lock(s->dirty_bitmap); 485 offset = bdrv_dirty_iter_next(s->dbi); 486 if (offset < 0) { 487 bdrv_set_dirty_iter(s->dbi, 0); 488 offset = bdrv_dirty_iter_next(s->dbi); 489 trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap)); 490 assert(offset >= 0); 491 } 492 bdrv_dirty_bitmap_unlock(s->dirty_bitmap); 493 494 /* 495 * Wait for concurrent requests to @offset. The next loop will limit the 496 * copied area based on in_flight_bitmap so we only copy an area that does 497 * not overlap with concurrent in-flight requests. Still, we would like to 498 * copy something, so wait until there are at least no more requests to the 499 * very beginning of the area. 500 */ 501 mirror_wait_on_conflicts(NULL, s, offset, 1); 502 503 job_pause_point(&s->common.job); 504 505 /* Find the number of consective dirty chunks following the first dirty 506 * one, and wait for in flight requests in them. */ 507 bdrv_dirty_bitmap_lock(s->dirty_bitmap); 508 while (nb_chunks * s->granularity < s->buf_size) { 509 int64_t next_dirty; 510 int64_t next_offset = offset + nb_chunks * s->granularity; 511 int64_t next_chunk = next_offset / s->granularity; 512 if (next_offset >= s->bdev_length || 513 !bdrv_dirty_bitmap_get_locked(s->dirty_bitmap, next_offset)) { 514 break; 515 } 516 if (test_bit(next_chunk, s->in_flight_bitmap)) { 517 break; 518 } 519 520 next_dirty = bdrv_dirty_iter_next(s->dbi); 521 if (next_dirty > next_offset || next_dirty < 0) { 522 /* The bitmap iterator's cache is stale, refresh it */ 523 bdrv_set_dirty_iter(s->dbi, next_offset); 524 next_dirty = bdrv_dirty_iter_next(s->dbi); 525 } 526 assert(next_dirty == next_offset); 527 nb_chunks++; 528 } 529 530 /* Clear dirty bits before querying the block status, because 531 * calling bdrv_block_status_above could yield - if some blocks are 532 * marked dirty in this window, we need to know. 533 */ 534 bdrv_reset_dirty_bitmap_locked(s->dirty_bitmap, offset, 535 nb_chunks * s->granularity); 536 bdrv_dirty_bitmap_unlock(s->dirty_bitmap); 537 538 /* Before claiming an area in the in-flight bitmap, we have to 539 * create a MirrorOp for it so that conflicting requests can wait 540 * for it. mirror_perform() will create the real MirrorOps later, 541 * for now we just create a pseudo operation that will wake up all 542 * conflicting requests once all real operations have been 543 * launched. */ 544 pseudo_op = g_new(MirrorOp, 1); 545 *pseudo_op = (MirrorOp){ 546 .offset = offset, 547 .bytes = nb_chunks * s->granularity, 548 .is_pseudo_op = true, 549 }; 550 qemu_co_queue_init(&pseudo_op->waiting_requests); 551 QTAILQ_INSERT_TAIL(&s->ops_in_flight, pseudo_op, next); 552 553 bitmap_set(s->in_flight_bitmap, offset / s->granularity, nb_chunks); 554 while (nb_chunks > 0 && offset < s->bdev_length) { 555 int ret; 556 int64_t io_bytes; 557 int64_t io_bytes_acct; 558 MirrorMethod mirror_method = MIRROR_METHOD_COPY; 559 560 assert(!(offset % s->granularity)); 561 ret = bdrv_block_status_above(source, NULL, offset, 562 nb_chunks * s->granularity, 563 &io_bytes, NULL, NULL); 564 if (ret < 0) { 565 io_bytes = MIN(nb_chunks * s->granularity, max_io_bytes); 566 } else if (ret & BDRV_BLOCK_DATA) { 567 io_bytes = MIN(io_bytes, max_io_bytes); 568 } 569 570 io_bytes -= io_bytes % s->granularity; 571 if (io_bytes < s->granularity) { 572 io_bytes = s->granularity; 573 } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) { 574 int64_t target_offset; 575 int64_t target_bytes; 576 bdrv_round_to_clusters(blk_bs(s->target), offset, io_bytes, 577 &target_offset, &target_bytes); 578 if (target_offset == offset && 579 target_bytes == io_bytes) { 580 mirror_method = ret & BDRV_BLOCK_ZERO ? 581 MIRROR_METHOD_ZERO : 582 MIRROR_METHOD_DISCARD; 583 } 584 } 585 586 while (s->in_flight >= MAX_IN_FLIGHT) { 587 trace_mirror_yield_in_flight(s, offset, s->in_flight); 588 mirror_wait_for_free_in_flight_slot(s); 589 } 590 591 if (s->ret < 0) { 592 ret = 0; 593 goto fail; 594 } 595 596 io_bytes = mirror_clip_bytes(s, offset, io_bytes); 597 io_bytes = mirror_perform(s, offset, io_bytes, mirror_method); 598 if (mirror_method != MIRROR_METHOD_COPY && write_zeroes_ok) { 599 io_bytes_acct = 0; 600 } else { 601 io_bytes_acct = io_bytes; 602 } 603 assert(io_bytes); 604 offset += io_bytes; 605 nb_chunks -= DIV_ROUND_UP(io_bytes, s->granularity); 606 delay_ns = block_job_ratelimit_get_delay(&s->common, io_bytes_acct); 607 } 608 609 ret = delay_ns; 610 fail: 611 QTAILQ_REMOVE(&s->ops_in_flight, pseudo_op, next); 612 qemu_co_queue_restart_all(&pseudo_op->waiting_requests); 613 g_free(pseudo_op); 614 615 return ret; 616 } 617 618 static void mirror_free_init(MirrorBlockJob *s) 619 { 620 int granularity = s->granularity; 621 size_t buf_size = s->buf_size; 622 uint8_t *buf = s->buf; 623 624 assert(s->buf_free_count == 0); 625 QSIMPLEQ_INIT(&s->buf_free); 626 while (buf_size != 0) { 627 MirrorBuffer *cur = (MirrorBuffer *)buf; 628 QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); 629 s->buf_free_count++; 630 buf_size -= granularity; 631 buf += granularity; 632 } 633 } 634 635 /* This is also used for the .pause callback. There is no matching 636 * mirror_resume() because mirror_run() will begin iterating again 637 * when the job is resumed. 638 */ 639 static void coroutine_fn mirror_wait_for_all_io(MirrorBlockJob *s) 640 { 641 while (s->in_flight > 0) { 642 mirror_wait_for_free_in_flight_slot(s); 643 } 644 } 645 646 /** 647 * mirror_exit_common: handle both abort() and prepare() cases. 648 * for .prepare, returns 0 on success and -errno on failure. 649 * for .abort cases, denoted by abort = true, MUST return 0. 650 */ 651 static int mirror_exit_common(Job *job) 652 { 653 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 654 BlockJob *bjob = &s->common; 655 MirrorBDSOpaque *bs_opaque; 656 AioContext *replace_aio_context = NULL; 657 BlockDriverState *src; 658 BlockDriverState *target_bs; 659 BlockDriverState *mirror_top_bs; 660 Error *local_err = NULL; 661 bool abort = job->ret < 0; 662 int ret = 0; 663 664 if (s->prepared) { 665 return 0; 666 } 667 s->prepared = true; 668 669 mirror_top_bs = s->mirror_top_bs; 670 bs_opaque = mirror_top_bs->opaque; 671 src = mirror_top_bs->backing->bs; 672 target_bs = blk_bs(s->target); 673 674 if (bdrv_chain_contains(src, target_bs)) { 675 bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs); 676 } 677 678 bdrv_release_dirty_bitmap(s->dirty_bitmap); 679 680 /* Make sure that the source BDS doesn't go away during bdrv_replace_node, 681 * before we can call bdrv_drained_end */ 682 bdrv_ref(src); 683 bdrv_ref(mirror_top_bs); 684 bdrv_ref(target_bs); 685 686 /* 687 * Remove target parent that still uses BLK_PERM_WRITE/RESIZE before 688 * inserting target_bs at s->to_replace, where we might not be able to get 689 * these permissions. 690 */ 691 blk_unref(s->target); 692 s->target = NULL; 693 694 /* We don't access the source any more. Dropping any WRITE/RESIZE is 695 * required before it could become a backing file of target_bs. Not having 696 * these permissions any more means that we can't allow any new requests on 697 * mirror_top_bs from now on, so keep it drained. */ 698 bdrv_drained_begin(mirror_top_bs); 699 bs_opaque->stop = true; 700 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 701 &error_abort); 702 if (!abort && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { 703 BlockDriverState *backing = s->is_none_mode ? src : s->base; 704 BlockDriverState *unfiltered_target = bdrv_skip_filters(target_bs); 705 706 if (bdrv_cow_bs(unfiltered_target) != backing) { 707 bdrv_set_backing_hd(unfiltered_target, backing, &local_err); 708 if (local_err) { 709 error_report_err(local_err); 710 local_err = NULL; 711 ret = -EPERM; 712 } 713 } 714 } else if (!abort && s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { 715 assert(!bdrv_backing_chain_next(target_bs)); 716 ret = bdrv_open_backing_file(bdrv_skip_filters(target_bs), NULL, 717 "backing", &local_err); 718 if (ret < 0) { 719 error_report_err(local_err); 720 local_err = NULL; 721 } 722 } 723 724 if (s->to_replace) { 725 replace_aio_context = bdrv_get_aio_context(s->to_replace); 726 aio_context_acquire(replace_aio_context); 727 } 728 729 if (s->should_complete && !abort) { 730 BlockDriverState *to_replace = s->to_replace ?: src; 731 bool ro = bdrv_is_read_only(to_replace); 732 733 if (ro != bdrv_is_read_only(target_bs)) { 734 bdrv_reopen_set_read_only(target_bs, ro, NULL); 735 } 736 737 /* The mirror job has no requests in flight any more, but we need to 738 * drain potential other users of the BDS before changing the graph. */ 739 assert(s->in_drain); 740 bdrv_drained_begin(target_bs); 741 /* 742 * Cannot use check_to_replace_node() here, because that would 743 * check for an op blocker on @to_replace, and we have our own 744 * there. 745 */ 746 if (bdrv_recurse_can_replace(src, to_replace)) { 747 bdrv_replace_node(to_replace, target_bs, &local_err); 748 } else { 749 error_setg(&local_err, "Can no longer replace '%s' by '%s', " 750 "because it can no longer be guaranteed that doing so " 751 "would not lead to an abrupt change of visible data", 752 to_replace->node_name, target_bs->node_name); 753 } 754 bdrv_drained_end(target_bs); 755 if (local_err) { 756 error_report_err(local_err); 757 ret = -EPERM; 758 } 759 } 760 if (s->to_replace) { 761 bdrv_op_unblock_all(s->to_replace, s->replace_blocker); 762 error_free(s->replace_blocker); 763 bdrv_unref(s->to_replace); 764 } 765 if (replace_aio_context) { 766 aio_context_release(replace_aio_context); 767 } 768 g_free(s->replaces); 769 bdrv_unref(target_bs); 770 771 /* 772 * Remove the mirror filter driver from the graph. Before this, get rid of 773 * the blockers on the intermediate nodes so that the resulting state is 774 * valid. 775 */ 776 block_job_remove_all_bdrv(bjob); 777 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort); 778 779 bs_opaque->job = NULL; 780 781 bdrv_drained_end(src); 782 bdrv_drained_end(mirror_top_bs); 783 s->in_drain = false; 784 bdrv_unref(mirror_top_bs); 785 bdrv_unref(src); 786 787 return ret; 788 } 789 790 static int mirror_prepare(Job *job) 791 { 792 return mirror_exit_common(job); 793 } 794 795 static void mirror_abort(Job *job) 796 { 797 int ret = mirror_exit_common(job); 798 assert(ret == 0); 799 } 800 801 static void coroutine_fn mirror_throttle(MirrorBlockJob *s) 802 { 803 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 804 805 if (now - s->last_pause_ns > BLOCK_JOB_SLICE_TIME) { 806 s->last_pause_ns = now; 807 job_sleep_ns(&s->common.job, 0); 808 } else { 809 job_pause_point(&s->common.job); 810 } 811 } 812 813 static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) 814 { 815 int64_t offset; 816 BlockDriverState *bs = s->mirror_top_bs->backing->bs; 817 BlockDriverState *target_bs = blk_bs(s->target); 818 int ret; 819 int64_t count; 820 821 if (s->zero_target) { 822 if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { 823 bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length); 824 return 0; 825 } 826 827 s->initial_zeroing_ongoing = true; 828 for (offset = 0; offset < s->bdev_length; ) { 829 int bytes = MIN(s->bdev_length - offset, 830 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 831 832 mirror_throttle(s); 833 834 if (job_is_cancelled(&s->common.job)) { 835 s->initial_zeroing_ongoing = false; 836 return 0; 837 } 838 839 if (s->in_flight >= MAX_IN_FLIGHT) { 840 trace_mirror_yield(s, UINT64_MAX, s->buf_free_count, 841 s->in_flight); 842 mirror_wait_for_free_in_flight_slot(s); 843 continue; 844 } 845 846 mirror_perform(s, offset, bytes, MIRROR_METHOD_ZERO); 847 offset += bytes; 848 } 849 850 mirror_wait_for_all_io(s); 851 s->initial_zeroing_ongoing = false; 852 } 853 854 /* First part, loop on the sectors and initialize the dirty bitmap. */ 855 for (offset = 0; offset < s->bdev_length; ) { 856 /* Just to make sure we are not exceeding int limit. */ 857 int bytes = MIN(s->bdev_length - offset, 858 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 859 860 mirror_throttle(s); 861 862 if (job_is_cancelled(&s->common.job)) { 863 return 0; 864 } 865 866 ret = bdrv_is_allocated_above(bs, s->base_overlay, true, offset, bytes, 867 &count); 868 if (ret < 0) { 869 return ret; 870 } 871 872 assert(count); 873 if (ret > 0) { 874 bdrv_set_dirty_bitmap(s->dirty_bitmap, offset, count); 875 } 876 offset += count; 877 } 878 return 0; 879 } 880 881 /* Called when going out of the streaming phase to flush the bulk of the 882 * data to the medium, or just before completing. 883 */ 884 static int mirror_flush(MirrorBlockJob *s) 885 { 886 int ret = blk_flush(s->target); 887 if (ret < 0) { 888 if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) { 889 s->ret = ret; 890 } 891 } 892 return ret; 893 } 894 895 static int coroutine_fn mirror_run(Job *job, Error **errp) 896 { 897 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 898 BlockDriverState *bs = s->mirror_top_bs->backing->bs; 899 BlockDriverState *target_bs = blk_bs(s->target); 900 bool need_drain = true; 901 BlockDeviceIoStatus iostatus; 902 int64_t length; 903 int64_t target_length; 904 BlockDriverInfo bdi; 905 char backing_filename[2]; /* we only need 2 characters because we are only 906 checking for a NULL string */ 907 int ret = 0; 908 909 if (job_is_cancelled(&s->common.job)) { 910 goto immediate_exit; 911 } 912 913 s->bdev_length = bdrv_co_getlength(bs); 914 if (s->bdev_length < 0) { 915 ret = s->bdev_length; 916 goto immediate_exit; 917 } 918 919 target_length = blk_co_getlength(s->target); 920 if (target_length < 0) { 921 ret = target_length; 922 goto immediate_exit; 923 } 924 925 /* Active commit must resize the base image if its size differs from the 926 * active layer. */ 927 if (s->base == blk_bs(s->target)) { 928 if (s->bdev_length > target_length) { 929 ret = blk_co_truncate(s->target, s->bdev_length, false, 930 PREALLOC_MODE_OFF, 0, NULL); 931 if (ret < 0) { 932 goto immediate_exit; 933 } 934 } 935 } else if (s->bdev_length != target_length) { 936 error_setg(errp, "Source and target image have different sizes"); 937 ret = -EINVAL; 938 goto immediate_exit; 939 } 940 941 if (s->bdev_length == 0) { 942 /* Transition to the READY state and wait for complete. */ 943 job_transition_to_ready(&s->common.job); 944 s->actively_synced = true; 945 while (!job_cancel_requested(&s->common.job) && !s->should_complete) { 946 job_yield(&s->common.job); 947 } 948 goto immediate_exit; 949 } 950 951 length = DIV_ROUND_UP(s->bdev_length, s->granularity); 952 s->in_flight_bitmap = bitmap_new(length); 953 954 /* If we have no backing file yet in the destination, we cannot let 955 * the destination do COW. Instead, we copy sectors around the 956 * dirty data if needed. We need a bitmap to do that. 957 */ 958 bdrv_get_backing_filename(target_bs, backing_filename, 959 sizeof(backing_filename)); 960 if (!bdrv_co_get_info(target_bs, &bdi) && bdi.cluster_size) { 961 s->target_cluster_size = bdi.cluster_size; 962 } else { 963 s->target_cluster_size = BDRV_SECTOR_SIZE; 964 } 965 if (backing_filename[0] && !bdrv_backing_chain_next(target_bs) && 966 s->granularity < s->target_cluster_size) { 967 s->buf_size = MAX(s->buf_size, s->target_cluster_size); 968 s->cow_bitmap = bitmap_new(length); 969 } 970 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); 971 972 s->buf = qemu_try_blockalign(bs, s->buf_size); 973 if (s->buf == NULL) { 974 ret = -ENOMEM; 975 goto immediate_exit; 976 } 977 978 mirror_free_init(s); 979 980 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 981 if (!s->is_none_mode) { 982 ret = mirror_dirty_init(s); 983 if (ret < 0 || job_is_cancelled(&s->common.job)) { 984 goto immediate_exit; 985 } 986 } 987 988 assert(!s->dbi); 989 s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap); 990 for (;;) { 991 uint64_t delay_ns = 0; 992 int64_t cnt, delta; 993 bool should_complete; 994 995 if (s->ret < 0) { 996 ret = s->ret; 997 goto immediate_exit; 998 } 999 1000 job_pause_point(&s->common.job); 1001 1002 if (job_is_cancelled(&s->common.job)) { 1003 ret = 0; 1004 goto immediate_exit; 1005 } 1006 1007 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1008 /* cnt is the number of dirty bytes remaining and s->bytes_in_flight is 1009 * the number of bytes currently being processed; together those are 1010 * the current remaining operation length */ 1011 job_progress_set_remaining(&s->common.job, 1012 s->bytes_in_flight + cnt + 1013 s->active_write_bytes_in_flight); 1014 1015 /* Note that even when no rate limit is applied we need to yield 1016 * periodically with no pending I/O so that bdrv_drain_all() returns. 1017 * We do so every BLKOCK_JOB_SLICE_TIME nanoseconds, or when there is 1018 * an error, or when the source is clean, whichever comes first. */ 1019 delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns; 1020 WITH_JOB_LOCK_GUARD() { 1021 iostatus = s->common.iostatus; 1022 } 1023 if (delta < BLOCK_JOB_SLICE_TIME && 1024 iostatus == BLOCK_DEVICE_IO_STATUS_OK) { 1025 if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || 1026 (cnt == 0 && s->in_flight > 0)) { 1027 trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight); 1028 mirror_wait_for_free_in_flight_slot(s); 1029 continue; 1030 } else if (cnt != 0) { 1031 delay_ns = mirror_iteration(s); 1032 } 1033 } 1034 1035 should_complete = false; 1036 if (s->in_flight == 0 && cnt == 0) { 1037 trace_mirror_before_flush(s); 1038 if (!job_is_ready(&s->common.job)) { 1039 if (mirror_flush(s) < 0) { 1040 /* Go check s->ret. */ 1041 continue; 1042 } 1043 /* We're out of the streaming phase. From now on, if the job 1044 * is cancelled we will actually complete all pending I/O and 1045 * report completion. This way, block-job-cancel will leave 1046 * the target in a consistent state. 1047 */ 1048 job_transition_to_ready(&s->common.job); 1049 if (s->copy_mode != MIRROR_COPY_MODE_BACKGROUND) { 1050 s->actively_synced = true; 1051 } 1052 } 1053 1054 should_complete = s->should_complete || 1055 job_cancel_requested(&s->common.job); 1056 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1057 } 1058 1059 if (cnt == 0 && should_complete) { 1060 /* The dirty bitmap is not updated while operations are pending. 1061 * If we're about to exit, wait for pending operations before 1062 * calling bdrv_get_dirty_count(bs), or we may exit while the 1063 * source has dirty data to copy! 1064 * 1065 * Note that I/O can be submitted by the guest while 1066 * mirror_populate runs, so pause it now. Before deciding 1067 * whether to switch to target check one last time if I/O has 1068 * come in the meanwhile, and if not flush the data to disk. 1069 */ 1070 trace_mirror_before_drain(s, cnt); 1071 1072 s->in_drain = true; 1073 bdrv_drained_begin(bs); 1074 1075 /* Must be zero because we are drained */ 1076 assert(s->in_active_write_counter == 0); 1077 1078 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1079 if (cnt > 0 || mirror_flush(s) < 0) { 1080 bdrv_drained_end(bs); 1081 s->in_drain = false; 1082 continue; 1083 } 1084 1085 /* The two disks are in sync. Exit and report successful 1086 * completion. 1087 */ 1088 assert(QLIST_EMPTY(&bs->tracked_requests)); 1089 need_drain = false; 1090 break; 1091 } 1092 1093 if (job_is_ready(&s->common.job) && !should_complete) { 1094 delay_ns = (s->in_flight == 0 && 1095 cnt == 0 ? BLOCK_JOB_SLICE_TIME : 0); 1096 } 1097 trace_mirror_before_sleep(s, cnt, job_is_ready(&s->common.job), 1098 delay_ns); 1099 job_sleep_ns(&s->common.job, delay_ns); 1100 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 1101 } 1102 1103 immediate_exit: 1104 if (s->in_flight > 0) { 1105 /* We get here only if something went wrong. Either the job failed, 1106 * or it was cancelled prematurely so that we do not guarantee that 1107 * the target is a copy of the source. 1108 */ 1109 assert(ret < 0 || job_is_cancelled(&s->common.job)); 1110 assert(need_drain); 1111 mirror_wait_for_all_io(s); 1112 } 1113 1114 assert(s->in_flight == 0); 1115 qemu_vfree(s->buf); 1116 g_free(s->cow_bitmap); 1117 g_free(s->in_flight_bitmap); 1118 bdrv_dirty_iter_free(s->dbi); 1119 1120 if (need_drain) { 1121 s->in_drain = true; 1122 bdrv_drained_begin(bs); 1123 } 1124 1125 return ret; 1126 } 1127 1128 static void mirror_complete(Job *job, Error **errp) 1129 { 1130 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1131 1132 if (!job_is_ready(job)) { 1133 error_setg(errp, "The active block job '%s' cannot be completed", 1134 job->id); 1135 return; 1136 } 1137 1138 /* block all operations on to_replace bs */ 1139 if (s->replaces) { 1140 AioContext *replace_aio_context; 1141 1142 s->to_replace = bdrv_find_node(s->replaces); 1143 if (!s->to_replace) { 1144 error_setg(errp, "Node name '%s' not found", s->replaces); 1145 return; 1146 } 1147 1148 replace_aio_context = bdrv_get_aio_context(s->to_replace); 1149 aio_context_acquire(replace_aio_context); 1150 1151 /* TODO Translate this into child freeze system. */ 1152 error_setg(&s->replace_blocker, 1153 "block device is in use by block-job-complete"); 1154 bdrv_op_block_all(s->to_replace, s->replace_blocker); 1155 bdrv_ref(s->to_replace); 1156 1157 aio_context_release(replace_aio_context); 1158 } 1159 1160 s->should_complete = true; 1161 1162 /* If the job is paused, it will be re-entered when it is resumed */ 1163 WITH_JOB_LOCK_GUARD() { 1164 if (!job->paused) { 1165 job_enter_cond_locked(job, NULL); 1166 } 1167 } 1168 } 1169 1170 static void coroutine_fn mirror_pause(Job *job) 1171 { 1172 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1173 1174 mirror_wait_for_all_io(s); 1175 } 1176 1177 static bool mirror_drained_poll(BlockJob *job) 1178 { 1179 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1180 1181 /* If the job isn't paused nor cancelled, we can't be sure that it won't 1182 * issue more requests. We make an exception if we've reached this point 1183 * from one of our own drain sections, to avoid a deadlock waiting for 1184 * ourselves. 1185 */ 1186 WITH_JOB_LOCK_GUARD() { 1187 if (!s->common.job.paused && !job_is_cancelled_locked(&job->job) 1188 && !s->in_drain) { 1189 return true; 1190 } 1191 } 1192 1193 return !!s->in_flight; 1194 } 1195 1196 static bool mirror_cancel(Job *job, bool force) 1197 { 1198 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1199 BlockDriverState *target = blk_bs(s->target); 1200 1201 /* 1202 * Before the job is READY, we treat any cancellation like a 1203 * force-cancellation. 1204 */ 1205 force = force || !job_is_ready(job); 1206 1207 if (force) { 1208 bdrv_cancel_in_flight(target); 1209 } 1210 return force; 1211 } 1212 1213 static bool commit_active_cancel(Job *job, bool force) 1214 { 1215 /* Same as above in mirror_cancel() */ 1216 return force || !job_is_ready(job); 1217 } 1218 1219 static const BlockJobDriver mirror_job_driver = { 1220 .job_driver = { 1221 .instance_size = sizeof(MirrorBlockJob), 1222 .job_type = JOB_TYPE_MIRROR, 1223 .free = block_job_free, 1224 .user_resume = block_job_user_resume, 1225 .run = mirror_run, 1226 .prepare = mirror_prepare, 1227 .abort = mirror_abort, 1228 .pause = mirror_pause, 1229 .complete = mirror_complete, 1230 .cancel = mirror_cancel, 1231 }, 1232 .drained_poll = mirror_drained_poll, 1233 }; 1234 1235 static const BlockJobDriver commit_active_job_driver = { 1236 .job_driver = { 1237 .instance_size = sizeof(MirrorBlockJob), 1238 .job_type = JOB_TYPE_COMMIT, 1239 .free = block_job_free, 1240 .user_resume = block_job_user_resume, 1241 .run = mirror_run, 1242 .prepare = mirror_prepare, 1243 .abort = mirror_abort, 1244 .pause = mirror_pause, 1245 .complete = mirror_complete, 1246 .cancel = commit_active_cancel, 1247 }, 1248 .drained_poll = mirror_drained_poll, 1249 }; 1250 1251 static void coroutine_fn 1252 do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, 1253 uint64_t offset, uint64_t bytes, 1254 QEMUIOVector *qiov, int flags) 1255 { 1256 int ret; 1257 size_t qiov_offset = 0; 1258 int64_t bitmap_offset, bitmap_end; 1259 1260 if (!QEMU_IS_ALIGNED(offset, job->granularity) && 1261 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset)) 1262 { 1263 /* 1264 * Dirty unaligned padding: ignore it. 1265 * 1266 * Reasoning: 1267 * 1. If we copy it, we can't reset corresponding bit in 1268 * dirty_bitmap as there may be some "dirty" bytes still not 1269 * copied. 1270 * 2. It's already dirty, so skipping it we don't diverge mirror 1271 * progress. 1272 * 1273 * Note, that because of this, guest write may have no contribution 1274 * into mirror converge, but that's not bad, as we have background 1275 * process of mirroring. If under some bad circumstances (high guest 1276 * IO load) background process starve, we will not converge anyway, 1277 * even if each write will contribute, as guest is not guaranteed to 1278 * rewrite the whole disk. 1279 */ 1280 qiov_offset = QEMU_ALIGN_UP(offset, job->granularity) - offset; 1281 if (bytes <= qiov_offset) { 1282 /* nothing to do after shrink */ 1283 return; 1284 } 1285 offset += qiov_offset; 1286 bytes -= qiov_offset; 1287 } 1288 1289 if (!QEMU_IS_ALIGNED(offset + bytes, job->granularity) && 1290 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset + bytes - 1)) 1291 { 1292 uint64_t tail = (offset + bytes) % job->granularity; 1293 1294 if (bytes <= tail) { 1295 /* nothing to do after shrink */ 1296 return; 1297 } 1298 bytes -= tail; 1299 } 1300 1301 /* 1302 * Tails are either clean or shrunk, so for bitmap resetting 1303 * we safely align the range down. 1304 */ 1305 bitmap_offset = QEMU_ALIGN_UP(offset, job->granularity); 1306 bitmap_end = QEMU_ALIGN_DOWN(offset + bytes, job->granularity); 1307 if (bitmap_offset < bitmap_end) { 1308 bdrv_reset_dirty_bitmap(job->dirty_bitmap, bitmap_offset, 1309 bitmap_end - bitmap_offset); 1310 } 1311 1312 job_progress_increase_remaining(&job->common.job, bytes); 1313 job->active_write_bytes_in_flight += bytes; 1314 1315 switch (method) { 1316 case MIRROR_METHOD_COPY: 1317 ret = blk_co_pwritev_part(job->target, offset, bytes, 1318 qiov, qiov_offset, flags); 1319 break; 1320 1321 case MIRROR_METHOD_ZERO: 1322 assert(!qiov); 1323 ret = blk_co_pwrite_zeroes(job->target, offset, bytes, flags); 1324 break; 1325 1326 case MIRROR_METHOD_DISCARD: 1327 assert(!qiov); 1328 ret = blk_co_pdiscard(job->target, offset, bytes); 1329 break; 1330 1331 default: 1332 abort(); 1333 } 1334 1335 job->active_write_bytes_in_flight -= bytes; 1336 if (ret >= 0) { 1337 job_progress_update(&job->common.job, bytes); 1338 } else { 1339 BlockErrorAction action; 1340 1341 /* 1342 * We failed, so we should mark dirty the whole area, aligned up. 1343 * Note that we don't care about shrunk tails if any: they were dirty 1344 * at function start, and they must be still dirty, as we've locked 1345 * the region for in-flight op. 1346 */ 1347 bitmap_offset = QEMU_ALIGN_DOWN(offset, job->granularity); 1348 bitmap_end = QEMU_ALIGN_UP(offset + bytes, job->granularity); 1349 bdrv_set_dirty_bitmap(job->dirty_bitmap, bitmap_offset, 1350 bitmap_end - bitmap_offset); 1351 job->actively_synced = false; 1352 1353 action = mirror_error_action(job, false, -ret); 1354 if (action == BLOCK_ERROR_ACTION_REPORT) { 1355 if (!job->ret) { 1356 job->ret = ret; 1357 } 1358 } 1359 } 1360 } 1361 1362 static MirrorOp *coroutine_fn active_write_prepare(MirrorBlockJob *s, 1363 uint64_t offset, 1364 uint64_t bytes) 1365 { 1366 MirrorOp *op; 1367 uint64_t start_chunk = offset / s->granularity; 1368 uint64_t end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 1369 1370 op = g_new(MirrorOp, 1); 1371 *op = (MirrorOp){ 1372 .s = s, 1373 .offset = offset, 1374 .bytes = bytes, 1375 .is_active_write = true, 1376 .is_in_flight = true, 1377 .co = qemu_coroutine_self(), 1378 }; 1379 qemu_co_queue_init(&op->waiting_requests); 1380 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 1381 1382 s->in_active_write_counter++; 1383 1384 /* 1385 * Wait for concurrent requests affecting the area. If there are already 1386 * running requests that are copying off now-to-be stale data in the area, 1387 * we must wait for them to finish before we begin writing fresh data to the 1388 * target so that the write operations appear in the correct order. 1389 * Note that background requests (see mirror_iteration()) in contrast only 1390 * wait for conflicting requests at the start of the dirty area, and then 1391 * (based on the in_flight_bitmap) truncate the area to copy so it will not 1392 * conflict with any requests beyond that. For active writes, however, we 1393 * cannot truncate that area. The request from our parent must be blocked 1394 * until the area is copied in full. Therefore, we must wait for the whole 1395 * area to become free of concurrent requests. 1396 */ 1397 mirror_wait_on_conflicts(op, s, offset, bytes); 1398 1399 bitmap_set(s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1400 1401 return op; 1402 } 1403 1404 static void coroutine_fn active_write_settle(MirrorOp *op) 1405 { 1406 uint64_t start_chunk = op->offset / op->s->granularity; 1407 uint64_t end_chunk = DIV_ROUND_UP(op->offset + op->bytes, 1408 op->s->granularity); 1409 1410 if (!--op->s->in_active_write_counter && op->s->actively_synced) { 1411 BdrvChild *source = op->s->mirror_top_bs->backing; 1412 1413 if (QLIST_FIRST(&source->bs->parents) == source && 1414 QLIST_NEXT(source, next_parent) == NULL) 1415 { 1416 /* Assert that we are back in sync once all active write 1417 * operations are settled. 1418 * Note that we can only assert this if the mirror node 1419 * is the source node's only parent. */ 1420 assert(!bdrv_get_dirty_count(op->s->dirty_bitmap)); 1421 } 1422 } 1423 bitmap_clear(op->s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1424 QTAILQ_REMOVE(&op->s->ops_in_flight, op, next); 1425 qemu_co_queue_restart_all(&op->waiting_requests); 1426 g_free(op); 1427 } 1428 1429 static int coroutine_fn bdrv_mirror_top_preadv(BlockDriverState *bs, 1430 int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags) 1431 { 1432 return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); 1433 } 1434 1435 static int coroutine_fn bdrv_mirror_top_do_write(BlockDriverState *bs, 1436 MirrorMethod method, uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, 1437 int flags) 1438 { 1439 MirrorOp *op = NULL; 1440 MirrorBDSOpaque *s = bs->opaque; 1441 int ret = 0; 1442 bool copy_to_target = false; 1443 1444 if (s->job) { 1445 copy_to_target = s->job->ret >= 0 && 1446 !job_is_cancelled(&s->job->common.job) && 1447 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING; 1448 } 1449 1450 if (copy_to_target) { 1451 op = active_write_prepare(s->job, offset, bytes); 1452 } 1453 1454 switch (method) { 1455 case MIRROR_METHOD_COPY: 1456 ret = bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags); 1457 break; 1458 1459 case MIRROR_METHOD_ZERO: 1460 ret = bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags); 1461 break; 1462 1463 case MIRROR_METHOD_DISCARD: 1464 ret = bdrv_co_pdiscard(bs->backing, offset, bytes); 1465 break; 1466 1467 default: 1468 abort(); 1469 } 1470 1471 if (ret < 0) { 1472 goto out; 1473 } 1474 1475 if (copy_to_target) { 1476 do_sync_target_write(s->job, method, offset, bytes, qiov, flags); 1477 } 1478 1479 out: 1480 if (copy_to_target) { 1481 active_write_settle(op); 1482 } 1483 return ret; 1484 } 1485 1486 static int coroutine_fn bdrv_mirror_top_pwritev(BlockDriverState *bs, 1487 int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags) 1488 { 1489 MirrorBDSOpaque *s = bs->opaque; 1490 QEMUIOVector bounce_qiov; 1491 void *bounce_buf; 1492 int ret = 0; 1493 bool copy_to_target = false; 1494 1495 if (s->job) { 1496 copy_to_target = s->job->ret >= 0 && 1497 !job_is_cancelled(&s->job->common.job) && 1498 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING; 1499 } 1500 1501 if (copy_to_target) { 1502 /* The guest might concurrently modify the data to write; but 1503 * the data on source and destination must match, so we have 1504 * to use a bounce buffer if we are going to write to the 1505 * target now. */ 1506 bounce_buf = qemu_blockalign(bs, bytes); 1507 iov_to_buf_full(qiov->iov, qiov->niov, 0, bounce_buf, bytes); 1508 1509 qemu_iovec_init(&bounce_qiov, 1); 1510 qemu_iovec_add(&bounce_qiov, bounce_buf, bytes); 1511 qiov = &bounce_qiov; 1512 1513 flags &= ~BDRV_REQ_REGISTERED_BUF; 1514 } 1515 1516 ret = bdrv_mirror_top_do_write(bs, MIRROR_METHOD_COPY, offset, bytes, qiov, 1517 flags); 1518 1519 if (copy_to_target) { 1520 qemu_iovec_destroy(&bounce_qiov); 1521 qemu_vfree(bounce_buf); 1522 } 1523 1524 return ret; 1525 } 1526 1527 static int coroutine_fn bdrv_mirror_top_flush(BlockDriverState *bs) 1528 { 1529 if (bs->backing == NULL) { 1530 /* we can be here after failed bdrv_append in mirror_start_job */ 1531 return 0; 1532 } 1533 return bdrv_co_flush(bs->backing->bs); 1534 } 1535 1536 static int coroutine_fn bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs, 1537 int64_t offset, int64_t bytes, BdrvRequestFlags flags) 1538 { 1539 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_ZERO, offset, bytes, NULL, 1540 flags); 1541 } 1542 1543 static int coroutine_fn bdrv_mirror_top_pdiscard(BlockDriverState *bs, 1544 int64_t offset, int64_t bytes) 1545 { 1546 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_DISCARD, offset, bytes, 1547 NULL, 0); 1548 } 1549 1550 static void bdrv_mirror_top_refresh_filename(BlockDriverState *bs) 1551 { 1552 if (bs->backing == NULL) { 1553 /* we can be here after failed bdrv_attach_child in 1554 * bdrv_set_backing_hd */ 1555 return; 1556 } 1557 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), 1558 bs->backing->bs->filename); 1559 } 1560 1561 static void bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c, 1562 BdrvChildRole role, 1563 BlockReopenQueue *reopen_queue, 1564 uint64_t perm, uint64_t shared, 1565 uint64_t *nperm, uint64_t *nshared) 1566 { 1567 MirrorBDSOpaque *s = bs->opaque; 1568 1569 if (s->stop) { 1570 /* 1571 * If the job is to be stopped, we do not need to forward 1572 * anything to the real image. 1573 */ 1574 *nperm = 0; 1575 *nshared = BLK_PERM_ALL; 1576 return; 1577 } 1578 1579 bdrv_default_perms(bs, c, role, reopen_queue, 1580 perm, shared, nperm, nshared); 1581 1582 if (s->is_commit) { 1583 /* 1584 * For commit jobs, we cannot take CONSISTENT_READ, because 1585 * that permission is unshared for everything above the base 1586 * node (except for filters on the base node). 1587 * We also have to force-share the WRITE permission, or 1588 * otherwise we would block ourselves at the base node (if 1589 * writes are blocked for a node, they are also blocked for 1590 * its backing file). 1591 * (We could also share RESIZE, because it may be needed for 1592 * the target if its size is less than the top node's; but 1593 * bdrv_default_perms_for_cow() automatically shares RESIZE 1594 * for backing nodes if WRITE is shared, so there is no need 1595 * to do it here.) 1596 */ 1597 *nperm &= ~BLK_PERM_CONSISTENT_READ; 1598 *nshared |= BLK_PERM_WRITE; 1599 } 1600 } 1601 1602 /* Dummy node that provides consistent read to its users without requiring it 1603 * from its backing file and that allows writes on the backing file chain. */ 1604 static BlockDriver bdrv_mirror_top = { 1605 .format_name = "mirror_top", 1606 .bdrv_co_preadv = bdrv_mirror_top_preadv, 1607 .bdrv_co_pwritev = bdrv_mirror_top_pwritev, 1608 .bdrv_co_pwrite_zeroes = bdrv_mirror_top_pwrite_zeroes, 1609 .bdrv_co_pdiscard = bdrv_mirror_top_pdiscard, 1610 .bdrv_co_flush = bdrv_mirror_top_flush, 1611 .bdrv_refresh_filename = bdrv_mirror_top_refresh_filename, 1612 .bdrv_child_perm = bdrv_mirror_top_child_perm, 1613 1614 .is_filter = true, 1615 .filtered_child_is_backing = true, 1616 }; 1617 1618 static BlockJob *mirror_start_job( 1619 const char *job_id, BlockDriverState *bs, 1620 int creation_flags, BlockDriverState *target, 1621 const char *replaces, int64_t speed, 1622 uint32_t granularity, int64_t buf_size, 1623 BlockMirrorBackingMode backing_mode, 1624 bool zero_target, 1625 BlockdevOnError on_source_error, 1626 BlockdevOnError on_target_error, 1627 bool unmap, 1628 BlockCompletionFunc *cb, 1629 void *opaque, 1630 const BlockJobDriver *driver, 1631 bool is_none_mode, BlockDriverState *base, 1632 bool auto_complete, const char *filter_node_name, 1633 bool is_mirror, MirrorCopyMode copy_mode, 1634 Error **errp) 1635 { 1636 MirrorBlockJob *s; 1637 MirrorBDSOpaque *bs_opaque; 1638 BlockDriverState *mirror_top_bs; 1639 bool target_is_backing; 1640 uint64_t target_perms, target_shared_perms; 1641 int ret; 1642 1643 if (granularity == 0) { 1644 granularity = bdrv_get_default_bitmap_granularity(target); 1645 } 1646 1647 assert(is_power_of_2(granularity)); 1648 1649 if (buf_size < 0) { 1650 error_setg(errp, "Invalid parameter 'buf-size'"); 1651 return NULL; 1652 } 1653 1654 if (buf_size == 0) { 1655 buf_size = DEFAULT_MIRROR_BUF_SIZE; 1656 } 1657 1658 if (bdrv_skip_filters(bs) == bdrv_skip_filters(target)) { 1659 error_setg(errp, "Can't mirror node into itself"); 1660 return NULL; 1661 } 1662 1663 target_is_backing = bdrv_chain_contains(bs, target); 1664 1665 /* In the case of active commit, add dummy driver to provide consistent 1666 * reads on the top, while disabling it in the intermediate nodes, and make 1667 * the backing chain writable. */ 1668 mirror_top_bs = bdrv_new_open_driver(&bdrv_mirror_top, filter_node_name, 1669 BDRV_O_RDWR, errp); 1670 if (mirror_top_bs == NULL) { 1671 return NULL; 1672 } 1673 if (!filter_node_name) { 1674 mirror_top_bs->implicit = true; 1675 } 1676 1677 /* So that we can always drop this node */ 1678 mirror_top_bs->never_freeze = true; 1679 1680 mirror_top_bs->total_sectors = bs->total_sectors; 1681 mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED; 1682 mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED | 1683 BDRV_REQ_NO_FALLBACK; 1684 bs_opaque = g_new0(MirrorBDSOpaque, 1); 1685 mirror_top_bs->opaque = bs_opaque; 1686 1687 bs_opaque->is_commit = target_is_backing; 1688 1689 bdrv_drained_begin(bs); 1690 ret = bdrv_append(mirror_top_bs, bs, errp); 1691 bdrv_drained_end(bs); 1692 1693 if (ret < 0) { 1694 bdrv_unref(mirror_top_bs); 1695 return NULL; 1696 } 1697 1698 /* Make sure that the source is not resized while the job is running */ 1699 s = block_job_create(job_id, driver, NULL, mirror_top_bs, 1700 BLK_PERM_CONSISTENT_READ, 1701 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | 1702 BLK_PERM_WRITE, speed, 1703 creation_flags, cb, opaque, errp); 1704 if (!s) { 1705 goto fail; 1706 } 1707 bs_opaque->job = s; 1708 1709 /* The block job now has a reference to this node */ 1710 bdrv_unref(mirror_top_bs); 1711 1712 s->mirror_top_bs = mirror_top_bs; 1713 1714 /* No resize for the target either; while the mirror is still running, a 1715 * consistent read isn't necessarily possible. We could possibly allow 1716 * writes and graph modifications, though it would likely defeat the 1717 * purpose of a mirror, so leave them blocked for now. 1718 * 1719 * In the case of active commit, things look a bit different, though, 1720 * because the target is an already populated backing file in active use. 1721 * We can allow anything except resize there.*/ 1722 1723 target_perms = BLK_PERM_WRITE; 1724 target_shared_perms = BLK_PERM_WRITE_UNCHANGED; 1725 1726 if (target_is_backing) { 1727 int64_t bs_size, target_size; 1728 bs_size = bdrv_getlength(bs); 1729 if (bs_size < 0) { 1730 error_setg_errno(errp, -bs_size, 1731 "Could not inquire top image size"); 1732 goto fail; 1733 } 1734 1735 target_size = bdrv_getlength(target); 1736 if (target_size < 0) { 1737 error_setg_errno(errp, -target_size, 1738 "Could not inquire base image size"); 1739 goto fail; 1740 } 1741 1742 if (target_size < bs_size) { 1743 target_perms |= BLK_PERM_RESIZE; 1744 } 1745 1746 target_shared_perms |= BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE; 1747 } else if (bdrv_chain_contains(bs, bdrv_skip_filters(target))) { 1748 /* 1749 * We may want to allow this in the future, but it would 1750 * require taking some extra care. 1751 */ 1752 error_setg(errp, "Cannot mirror to a filter on top of a node in the " 1753 "source's backing chain"); 1754 goto fail; 1755 } 1756 1757 s->target = blk_new(s->common.job.aio_context, 1758 target_perms, target_shared_perms); 1759 ret = blk_insert_bs(s->target, target, errp); 1760 if (ret < 0) { 1761 goto fail; 1762 } 1763 if (is_mirror) { 1764 /* XXX: Mirror target could be a NBD server of target QEMU in the case 1765 * of non-shared block migration. To allow migration completion, we 1766 * have to allow "inactivate" of the target BB. When that happens, we 1767 * know the job is drained, and the vcpus are stopped, so no write 1768 * operation will be performed. Block layer already has assertions to 1769 * ensure that. */ 1770 blk_set_force_allow_inactivate(s->target); 1771 } 1772 blk_set_allow_aio_context_change(s->target, true); 1773 blk_set_disable_request_queuing(s->target, true); 1774 1775 s->replaces = g_strdup(replaces); 1776 s->on_source_error = on_source_error; 1777 s->on_target_error = on_target_error; 1778 s->is_none_mode = is_none_mode; 1779 s->backing_mode = backing_mode; 1780 s->zero_target = zero_target; 1781 s->copy_mode = copy_mode; 1782 s->base = base; 1783 s->base_overlay = bdrv_find_overlay(bs, base); 1784 s->granularity = granularity; 1785 s->buf_size = ROUND_UP(buf_size, granularity); 1786 s->unmap = unmap; 1787 if (auto_complete) { 1788 s->should_complete = true; 1789 } 1790 1791 s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp); 1792 if (!s->dirty_bitmap) { 1793 goto fail; 1794 } 1795 if (s->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING) { 1796 bdrv_disable_dirty_bitmap(s->dirty_bitmap); 1797 } 1798 1799 ret = block_job_add_bdrv(&s->common, "source", bs, 0, 1800 BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE | 1801 BLK_PERM_CONSISTENT_READ, 1802 errp); 1803 if (ret < 0) { 1804 goto fail; 1805 } 1806 1807 /* Required permissions are already taken with blk_new() */ 1808 block_job_add_bdrv(&s->common, "target", target, 0, BLK_PERM_ALL, 1809 &error_abort); 1810 1811 /* In commit_active_start() all intermediate nodes disappear, so 1812 * any jobs in them must be blocked */ 1813 if (target_is_backing) { 1814 BlockDriverState *iter, *filtered_target; 1815 uint64_t iter_shared_perms; 1816 1817 /* 1818 * The topmost node with 1819 * bdrv_skip_filters(filtered_target) == bdrv_skip_filters(target) 1820 */ 1821 filtered_target = bdrv_cow_bs(bdrv_find_overlay(bs, target)); 1822 1823 assert(bdrv_skip_filters(filtered_target) == 1824 bdrv_skip_filters(target)); 1825 1826 /* 1827 * XXX BLK_PERM_WRITE needs to be allowed so we don't block 1828 * ourselves at s->base (if writes are blocked for a node, they are 1829 * also blocked for its backing file). The other options would be a 1830 * second filter driver above s->base (== target). 1831 */ 1832 iter_shared_perms = BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE; 1833 1834 for (iter = bdrv_filter_or_cow_bs(bs); iter != target; 1835 iter = bdrv_filter_or_cow_bs(iter)) 1836 { 1837 if (iter == filtered_target) { 1838 /* 1839 * From here on, all nodes are filters on the base. 1840 * This allows us to share BLK_PERM_CONSISTENT_READ. 1841 */ 1842 iter_shared_perms |= BLK_PERM_CONSISTENT_READ; 1843 } 1844 1845 ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, 1846 iter_shared_perms, errp); 1847 if (ret < 0) { 1848 goto fail; 1849 } 1850 } 1851 1852 if (bdrv_freeze_backing_chain(mirror_top_bs, target, errp) < 0) { 1853 goto fail; 1854 } 1855 } 1856 1857 QTAILQ_INIT(&s->ops_in_flight); 1858 1859 trace_mirror_start(bs, s, opaque); 1860 job_start(&s->common.job); 1861 1862 return &s->common; 1863 1864 fail: 1865 if (s) { 1866 /* Make sure this BDS does not go away until we have completed the graph 1867 * changes below */ 1868 bdrv_ref(mirror_top_bs); 1869 1870 g_free(s->replaces); 1871 blk_unref(s->target); 1872 bs_opaque->job = NULL; 1873 if (s->dirty_bitmap) { 1874 bdrv_release_dirty_bitmap(s->dirty_bitmap); 1875 } 1876 job_early_fail(&s->common.job); 1877 } 1878 1879 bs_opaque->stop = true; 1880 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 1881 &error_abort); 1882 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort); 1883 1884 bdrv_unref(mirror_top_bs); 1885 1886 return NULL; 1887 } 1888 1889 void mirror_start(const char *job_id, BlockDriverState *bs, 1890 BlockDriverState *target, const char *replaces, 1891 int creation_flags, int64_t speed, 1892 uint32_t granularity, int64_t buf_size, 1893 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, 1894 bool zero_target, 1895 BlockdevOnError on_source_error, 1896 BlockdevOnError on_target_error, 1897 bool unmap, const char *filter_node_name, 1898 MirrorCopyMode copy_mode, Error **errp) 1899 { 1900 bool is_none_mode; 1901 BlockDriverState *base; 1902 1903 GLOBAL_STATE_CODE(); 1904 1905 if ((mode == MIRROR_SYNC_MODE_INCREMENTAL) || 1906 (mode == MIRROR_SYNC_MODE_BITMAP)) { 1907 error_setg(errp, "Sync mode '%s' not supported", 1908 MirrorSyncMode_str(mode)); 1909 return; 1910 } 1911 is_none_mode = mode == MIRROR_SYNC_MODE_NONE; 1912 base = mode == MIRROR_SYNC_MODE_TOP ? bdrv_backing_chain_next(bs) : NULL; 1913 mirror_start_job(job_id, bs, creation_flags, target, replaces, 1914 speed, granularity, buf_size, backing_mode, zero_target, 1915 on_source_error, on_target_error, unmap, NULL, NULL, 1916 &mirror_job_driver, is_none_mode, base, false, 1917 filter_node_name, true, copy_mode, errp); 1918 } 1919 1920 BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs, 1921 BlockDriverState *base, int creation_flags, 1922 int64_t speed, BlockdevOnError on_error, 1923 const char *filter_node_name, 1924 BlockCompletionFunc *cb, void *opaque, 1925 bool auto_complete, Error **errp) 1926 { 1927 bool base_read_only; 1928 BlockJob *job; 1929 1930 GLOBAL_STATE_CODE(); 1931 1932 base_read_only = bdrv_is_read_only(base); 1933 1934 if (base_read_only) { 1935 if (bdrv_reopen_set_read_only(base, false, errp) < 0) { 1936 return NULL; 1937 } 1938 } 1939 1940 job = mirror_start_job( 1941 job_id, bs, creation_flags, base, NULL, speed, 0, 0, 1942 MIRROR_LEAVE_BACKING_CHAIN, false, 1943 on_error, on_error, true, cb, opaque, 1944 &commit_active_job_driver, false, base, auto_complete, 1945 filter_node_name, false, MIRROR_COPY_MODE_BACKGROUND, 1946 errp); 1947 if (!job) { 1948 goto error_restore_flags; 1949 } 1950 1951 return job; 1952 1953 error_restore_flags: 1954 /* ignore error and errp for bdrv_reopen, because we want to propagate 1955 * the original error */ 1956 if (base_read_only) { 1957 bdrv_reopen_set_read_only(base, true, NULL); 1958 } 1959 return NULL; 1960 } 1961