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 WITH_GRAPH_RDLOCK_GUARD() { 393 ret = bdrv_co_preadv(s->mirror_top_bs->backing, op->offset, op->bytes, 394 &op->qiov, 0); 395 } 396 mirror_read_complete(op, ret); 397 } 398 399 static void coroutine_fn mirror_co_zero(void *opaque) 400 { 401 MirrorOp *op = opaque; 402 int ret; 403 404 op->s->in_flight++; 405 op->s->bytes_in_flight += op->bytes; 406 *op->bytes_handled = op->bytes; 407 op->is_in_flight = true; 408 409 ret = blk_co_pwrite_zeroes(op->s->target, op->offset, op->bytes, 410 op->s->unmap ? BDRV_REQ_MAY_UNMAP : 0); 411 mirror_write_complete(op, ret); 412 } 413 414 static void coroutine_fn mirror_co_discard(void *opaque) 415 { 416 MirrorOp *op = opaque; 417 int ret; 418 419 op->s->in_flight++; 420 op->s->bytes_in_flight += op->bytes; 421 *op->bytes_handled = op->bytes; 422 op->is_in_flight = true; 423 424 ret = blk_co_pdiscard(op->s->target, op->offset, op->bytes); 425 mirror_write_complete(op, ret); 426 } 427 428 static unsigned mirror_perform(MirrorBlockJob *s, int64_t offset, 429 unsigned bytes, MirrorMethod mirror_method) 430 { 431 MirrorOp *op; 432 Coroutine *co; 433 int64_t bytes_handled = -1; 434 435 op = g_new(MirrorOp, 1); 436 *op = (MirrorOp){ 437 .s = s, 438 .offset = offset, 439 .bytes = bytes, 440 .bytes_handled = &bytes_handled, 441 }; 442 qemu_co_queue_init(&op->waiting_requests); 443 444 switch (mirror_method) { 445 case MIRROR_METHOD_COPY: 446 co = qemu_coroutine_create(mirror_co_read, op); 447 break; 448 case MIRROR_METHOD_ZERO: 449 co = qemu_coroutine_create(mirror_co_zero, op); 450 break; 451 case MIRROR_METHOD_DISCARD: 452 co = qemu_coroutine_create(mirror_co_discard, op); 453 break; 454 default: 455 abort(); 456 } 457 op->co = co; 458 459 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 460 qemu_coroutine_enter(co); 461 /* At this point, ownership of op has been moved to the coroutine 462 * and the object may already be freed */ 463 464 /* Assert that this value has been set */ 465 assert(bytes_handled >= 0); 466 467 /* Same assertion as in mirror_co_read() (and for mirror_co_read() 468 * and mirror_co_discard(), bytes_handled == op->bytes, which 469 * is the @bytes parameter given to this function) */ 470 assert(bytes_handled <= UINT_MAX); 471 return bytes_handled; 472 } 473 474 static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) 475 { 476 BlockDriverState *source = s->mirror_top_bs->backing->bs; 477 MirrorOp *pseudo_op; 478 int64_t offset; 479 uint64_t delay_ns = 0, ret = 0; 480 /* At least the first dirty chunk is mirrored in one iteration. */ 481 int nb_chunks = 1; 482 bool write_zeroes_ok = bdrv_can_write_zeroes_with_unmap(blk_bs(s->target)); 483 int max_io_bytes = MAX(s->buf_size / MAX_IN_FLIGHT, MAX_IO_BYTES); 484 485 bdrv_dirty_bitmap_lock(s->dirty_bitmap); 486 offset = bdrv_dirty_iter_next(s->dbi); 487 if (offset < 0) { 488 bdrv_set_dirty_iter(s->dbi, 0); 489 offset = bdrv_dirty_iter_next(s->dbi); 490 trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap)); 491 assert(offset >= 0); 492 } 493 bdrv_dirty_bitmap_unlock(s->dirty_bitmap); 494 495 /* 496 * Wait for concurrent requests to @offset. The next loop will limit the 497 * copied area based on in_flight_bitmap so we only copy an area that does 498 * not overlap with concurrent in-flight requests. Still, we would like to 499 * copy something, so wait until there are at least no more requests to the 500 * very beginning of the area. 501 */ 502 mirror_wait_on_conflicts(NULL, s, offset, 1); 503 504 job_pause_point(&s->common.job); 505 506 /* Find the number of consective dirty chunks following the first dirty 507 * one, and wait for in flight requests in them. */ 508 bdrv_dirty_bitmap_lock(s->dirty_bitmap); 509 while (nb_chunks * s->granularity < s->buf_size) { 510 int64_t next_dirty; 511 int64_t next_offset = offset + nb_chunks * s->granularity; 512 int64_t next_chunk = next_offset / s->granularity; 513 if (next_offset >= s->bdev_length || 514 !bdrv_dirty_bitmap_get_locked(s->dirty_bitmap, next_offset)) { 515 break; 516 } 517 if (test_bit(next_chunk, s->in_flight_bitmap)) { 518 break; 519 } 520 521 next_dirty = bdrv_dirty_iter_next(s->dbi); 522 if (next_dirty > next_offset || next_dirty < 0) { 523 /* The bitmap iterator's cache is stale, refresh it */ 524 bdrv_set_dirty_iter(s->dbi, next_offset); 525 next_dirty = bdrv_dirty_iter_next(s->dbi); 526 } 527 assert(next_dirty == next_offset); 528 nb_chunks++; 529 } 530 531 /* Clear dirty bits before querying the block status, because 532 * calling bdrv_block_status_above could yield - if some blocks are 533 * marked dirty in this window, we need to know. 534 */ 535 bdrv_reset_dirty_bitmap_locked(s->dirty_bitmap, offset, 536 nb_chunks * s->granularity); 537 bdrv_dirty_bitmap_unlock(s->dirty_bitmap); 538 539 /* Before claiming an area in the in-flight bitmap, we have to 540 * create a MirrorOp for it so that conflicting requests can wait 541 * for it. mirror_perform() will create the real MirrorOps later, 542 * for now we just create a pseudo operation that will wake up all 543 * conflicting requests once all real operations have been 544 * launched. */ 545 pseudo_op = g_new(MirrorOp, 1); 546 *pseudo_op = (MirrorOp){ 547 .offset = offset, 548 .bytes = nb_chunks * s->granularity, 549 .is_pseudo_op = true, 550 }; 551 qemu_co_queue_init(&pseudo_op->waiting_requests); 552 QTAILQ_INSERT_TAIL(&s->ops_in_flight, pseudo_op, next); 553 554 bitmap_set(s->in_flight_bitmap, offset / s->granularity, nb_chunks); 555 while (nb_chunks > 0 && offset < s->bdev_length) { 556 int ret; 557 int64_t io_bytes; 558 int64_t io_bytes_acct; 559 MirrorMethod mirror_method = MIRROR_METHOD_COPY; 560 561 assert(!(offset % s->granularity)); 562 WITH_GRAPH_RDLOCK_GUARD() { 563 ret = bdrv_block_status_above(source, NULL, offset, 564 nb_chunks * s->granularity, 565 &io_bytes, NULL, NULL); 566 } 567 if (ret < 0) { 568 io_bytes = MIN(nb_chunks * s->granularity, max_io_bytes); 569 } else if (ret & BDRV_BLOCK_DATA) { 570 io_bytes = MIN(io_bytes, max_io_bytes); 571 } 572 573 io_bytes -= io_bytes % s->granularity; 574 if (io_bytes < s->granularity) { 575 io_bytes = s->granularity; 576 } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) { 577 int64_t target_offset; 578 int64_t target_bytes; 579 bdrv_round_to_clusters(blk_bs(s->target), offset, io_bytes, 580 &target_offset, &target_bytes); 581 if (target_offset == offset && 582 target_bytes == io_bytes) { 583 mirror_method = ret & BDRV_BLOCK_ZERO ? 584 MIRROR_METHOD_ZERO : 585 MIRROR_METHOD_DISCARD; 586 } 587 } 588 589 while (s->in_flight >= MAX_IN_FLIGHT) { 590 trace_mirror_yield_in_flight(s, offset, s->in_flight); 591 mirror_wait_for_free_in_flight_slot(s); 592 } 593 594 if (s->ret < 0) { 595 ret = 0; 596 goto fail; 597 } 598 599 io_bytes = mirror_clip_bytes(s, offset, io_bytes); 600 io_bytes = mirror_perform(s, offset, io_bytes, mirror_method); 601 if (mirror_method != MIRROR_METHOD_COPY && write_zeroes_ok) { 602 io_bytes_acct = 0; 603 } else { 604 io_bytes_acct = io_bytes; 605 } 606 assert(io_bytes); 607 offset += io_bytes; 608 nb_chunks -= DIV_ROUND_UP(io_bytes, s->granularity); 609 delay_ns = block_job_ratelimit_get_delay(&s->common, io_bytes_acct); 610 } 611 612 ret = delay_ns; 613 fail: 614 QTAILQ_REMOVE(&s->ops_in_flight, pseudo_op, next); 615 qemu_co_queue_restart_all(&pseudo_op->waiting_requests); 616 g_free(pseudo_op); 617 618 return ret; 619 } 620 621 static void mirror_free_init(MirrorBlockJob *s) 622 { 623 int granularity = s->granularity; 624 size_t buf_size = s->buf_size; 625 uint8_t *buf = s->buf; 626 627 assert(s->buf_free_count == 0); 628 QSIMPLEQ_INIT(&s->buf_free); 629 while (buf_size != 0) { 630 MirrorBuffer *cur = (MirrorBuffer *)buf; 631 QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); 632 s->buf_free_count++; 633 buf_size -= granularity; 634 buf += granularity; 635 } 636 } 637 638 /* This is also used for the .pause callback. There is no matching 639 * mirror_resume() because mirror_run() will begin iterating again 640 * when the job is resumed. 641 */ 642 static void coroutine_fn mirror_wait_for_all_io(MirrorBlockJob *s) 643 { 644 while (s->in_flight > 0) { 645 mirror_wait_for_free_in_flight_slot(s); 646 } 647 } 648 649 /** 650 * mirror_exit_common: handle both abort() and prepare() cases. 651 * for .prepare, returns 0 on success and -errno on failure. 652 * for .abort cases, denoted by abort = true, MUST return 0. 653 */ 654 static int mirror_exit_common(Job *job) 655 { 656 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 657 BlockJob *bjob = &s->common; 658 MirrorBDSOpaque *bs_opaque; 659 AioContext *replace_aio_context = NULL; 660 BlockDriverState *src; 661 BlockDriverState *target_bs; 662 BlockDriverState *mirror_top_bs; 663 Error *local_err = NULL; 664 bool abort = job->ret < 0; 665 int ret = 0; 666 667 if (s->prepared) { 668 return 0; 669 } 670 s->prepared = true; 671 672 mirror_top_bs = s->mirror_top_bs; 673 bs_opaque = mirror_top_bs->opaque; 674 src = mirror_top_bs->backing->bs; 675 target_bs = blk_bs(s->target); 676 677 if (bdrv_chain_contains(src, target_bs)) { 678 bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs); 679 } 680 681 bdrv_release_dirty_bitmap(s->dirty_bitmap); 682 683 /* Make sure that the source BDS doesn't go away during bdrv_replace_node, 684 * before we can call bdrv_drained_end */ 685 bdrv_ref(src); 686 bdrv_ref(mirror_top_bs); 687 bdrv_ref(target_bs); 688 689 /* 690 * Remove target parent that still uses BLK_PERM_WRITE/RESIZE before 691 * inserting target_bs at s->to_replace, where we might not be able to get 692 * these permissions. 693 */ 694 blk_unref(s->target); 695 s->target = NULL; 696 697 /* We don't access the source any more. Dropping any WRITE/RESIZE is 698 * required before it could become a backing file of target_bs. Not having 699 * these permissions any more means that we can't allow any new requests on 700 * mirror_top_bs from now on, so keep it drained. */ 701 bdrv_drained_begin(mirror_top_bs); 702 bs_opaque->stop = true; 703 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 704 &error_abort); 705 if (!abort && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { 706 BlockDriverState *backing = s->is_none_mode ? src : s->base; 707 BlockDriverState *unfiltered_target = bdrv_skip_filters(target_bs); 708 709 if (bdrv_cow_bs(unfiltered_target) != backing) { 710 bdrv_set_backing_hd(unfiltered_target, backing, &local_err); 711 if (local_err) { 712 error_report_err(local_err); 713 local_err = NULL; 714 ret = -EPERM; 715 } 716 } 717 } else if (!abort && s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { 718 assert(!bdrv_backing_chain_next(target_bs)); 719 ret = bdrv_open_backing_file(bdrv_skip_filters(target_bs), NULL, 720 "backing", &local_err); 721 if (ret < 0) { 722 error_report_err(local_err); 723 local_err = NULL; 724 } 725 } 726 727 if (s->to_replace) { 728 replace_aio_context = bdrv_get_aio_context(s->to_replace); 729 aio_context_acquire(replace_aio_context); 730 } 731 732 if (s->should_complete && !abort) { 733 BlockDriverState *to_replace = s->to_replace ?: src; 734 bool ro = bdrv_is_read_only(to_replace); 735 736 if (ro != bdrv_is_read_only(target_bs)) { 737 bdrv_reopen_set_read_only(target_bs, ro, NULL); 738 } 739 740 /* The mirror job has no requests in flight any more, but we need to 741 * drain potential other users of the BDS before changing the graph. */ 742 assert(s->in_drain); 743 bdrv_drained_begin(target_bs); 744 /* 745 * Cannot use check_to_replace_node() here, because that would 746 * check for an op blocker on @to_replace, and we have our own 747 * there. 748 */ 749 if (bdrv_recurse_can_replace(src, to_replace)) { 750 bdrv_replace_node(to_replace, target_bs, &local_err); 751 } else { 752 error_setg(&local_err, "Can no longer replace '%s' by '%s', " 753 "because it can no longer be guaranteed that doing so " 754 "would not lead to an abrupt change of visible data", 755 to_replace->node_name, target_bs->node_name); 756 } 757 bdrv_drained_end(target_bs); 758 if (local_err) { 759 error_report_err(local_err); 760 ret = -EPERM; 761 } 762 } 763 if (s->to_replace) { 764 bdrv_op_unblock_all(s->to_replace, s->replace_blocker); 765 error_free(s->replace_blocker); 766 bdrv_unref(s->to_replace); 767 } 768 if (replace_aio_context) { 769 aio_context_release(replace_aio_context); 770 } 771 g_free(s->replaces); 772 bdrv_unref(target_bs); 773 774 /* 775 * Remove the mirror filter driver from the graph. Before this, get rid of 776 * the blockers on the intermediate nodes so that the resulting state is 777 * valid. 778 */ 779 block_job_remove_all_bdrv(bjob); 780 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort); 781 782 bs_opaque->job = NULL; 783 784 bdrv_drained_end(src); 785 bdrv_drained_end(mirror_top_bs); 786 s->in_drain = false; 787 bdrv_unref(mirror_top_bs); 788 bdrv_unref(src); 789 790 return ret; 791 } 792 793 static int mirror_prepare(Job *job) 794 { 795 return mirror_exit_common(job); 796 } 797 798 static void mirror_abort(Job *job) 799 { 800 int ret = mirror_exit_common(job); 801 assert(ret == 0); 802 } 803 804 static void coroutine_fn mirror_throttle(MirrorBlockJob *s) 805 { 806 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 807 808 if (now - s->last_pause_ns > BLOCK_JOB_SLICE_TIME) { 809 s->last_pause_ns = now; 810 job_sleep_ns(&s->common.job, 0); 811 } else { 812 job_pause_point(&s->common.job); 813 } 814 } 815 816 static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) 817 { 818 int64_t offset; 819 BlockDriverState *bs = s->mirror_top_bs->backing->bs; 820 BlockDriverState *target_bs = blk_bs(s->target); 821 int ret; 822 int64_t count; 823 824 if (s->zero_target) { 825 if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { 826 bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length); 827 return 0; 828 } 829 830 s->initial_zeroing_ongoing = true; 831 for (offset = 0; offset < s->bdev_length; ) { 832 int bytes = MIN(s->bdev_length - offset, 833 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 834 835 mirror_throttle(s); 836 837 if (job_is_cancelled(&s->common.job)) { 838 s->initial_zeroing_ongoing = false; 839 return 0; 840 } 841 842 if (s->in_flight >= MAX_IN_FLIGHT) { 843 trace_mirror_yield(s, UINT64_MAX, s->buf_free_count, 844 s->in_flight); 845 mirror_wait_for_free_in_flight_slot(s); 846 continue; 847 } 848 849 mirror_perform(s, offset, bytes, MIRROR_METHOD_ZERO); 850 offset += bytes; 851 } 852 853 mirror_wait_for_all_io(s); 854 s->initial_zeroing_ongoing = false; 855 } 856 857 /* First part, loop on the sectors and initialize the dirty bitmap. */ 858 for (offset = 0; offset < s->bdev_length; ) { 859 /* Just to make sure we are not exceeding int limit. */ 860 int bytes = MIN(s->bdev_length - offset, 861 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 862 863 mirror_throttle(s); 864 865 if (job_is_cancelled(&s->common.job)) { 866 return 0; 867 } 868 869 WITH_GRAPH_RDLOCK_GUARD() { 870 ret = bdrv_is_allocated_above(bs, s->base_overlay, true, offset, 871 bytes, &count); 872 } 873 if (ret < 0) { 874 return ret; 875 } 876 877 assert(count); 878 if (ret > 0) { 879 bdrv_set_dirty_bitmap(s->dirty_bitmap, offset, count); 880 } 881 offset += count; 882 } 883 return 0; 884 } 885 886 /* Called when going out of the streaming phase to flush the bulk of the 887 * data to the medium, or just before completing. 888 */ 889 static int mirror_flush(MirrorBlockJob *s) 890 { 891 int ret = blk_flush(s->target); 892 if (ret < 0) { 893 if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) { 894 s->ret = ret; 895 } 896 } 897 return ret; 898 } 899 900 static int coroutine_fn mirror_run(Job *job, Error **errp) 901 { 902 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 903 BlockDriverState *bs = s->mirror_top_bs->backing->bs; 904 MirrorBDSOpaque *mirror_top_opaque = s->mirror_top_bs->opaque; 905 BlockDriverState *target_bs = blk_bs(s->target); 906 bool need_drain = true; 907 BlockDeviceIoStatus iostatus; 908 int64_t length; 909 int64_t target_length; 910 BlockDriverInfo bdi; 911 char backing_filename[2]; /* we only need 2 characters because we are only 912 checking for a NULL string */ 913 int ret = 0; 914 915 if (job_is_cancelled(&s->common.job)) { 916 goto immediate_exit; 917 } 918 919 bdrv_graph_co_rdlock(); 920 s->bdev_length = bdrv_co_getlength(bs); 921 bdrv_graph_co_rdunlock(); 922 923 if (s->bdev_length < 0) { 924 ret = s->bdev_length; 925 goto immediate_exit; 926 } 927 928 target_length = blk_co_getlength(s->target); 929 if (target_length < 0) { 930 ret = target_length; 931 goto immediate_exit; 932 } 933 934 /* Active commit must resize the base image if its size differs from the 935 * active layer. */ 936 if (s->base == blk_bs(s->target)) { 937 if (s->bdev_length > target_length) { 938 ret = blk_co_truncate(s->target, s->bdev_length, false, 939 PREALLOC_MODE_OFF, 0, NULL); 940 if (ret < 0) { 941 goto immediate_exit; 942 } 943 } 944 } else if (s->bdev_length != target_length) { 945 error_setg(errp, "Source and target image have different sizes"); 946 ret = -EINVAL; 947 goto immediate_exit; 948 } 949 950 if (s->bdev_length == 0) { 951 /* Transition to the READY state and wait for complete. */ 952 job_transition_to_ready(&s->common.job); 953 s->actively_synced = true; 954 while (!job_cancel_requested(&s->common.job) && !s->should_complete) { 955 job_yield(&s->common.job); 956 } 957 goto immediate_exit; 958 } 959 960 length = DIV_ROUND_UP(s->bdev_length, s->granularity); 961 s->in_flight_bitmap = bitmap_new(length); 962 963 /* If we have no backing file yet in the destination, we cannot let 964 * the destination do COW. Instead, we copy sectors around the 965 * dirty data if needed. We need a bitmap to do that. 966 */ 967 bdrv_get_backing_filename(target_bs, backing_filename, 968 sizeof(backing_filename)); 969 if (!bdrv_co_get_info(target_bs, &bdi) && bdi.cluster_size) { 970 s->target_cluster_size = bdi.cluster_size; 971 } else { 972 s->target_cluster_size = BDRV_SECTOR_SIZE; 973 } 974 if (backing_filename[0] && !bdrv_backing_chain_next(target_bs) && 975 s->granularity < s->target_cluster_size) { 976 s->buf_size = MAX(s->buf_size, s->target_cluster_size); 977 s->cow_bitmap = bitmap_new(length); 978 } 979 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); 980 981 s->buf = qemu_try_blockalign(bs, s->buf_size); 982 if (s->buf == NULL) { 983 ret = -ENOMEM; 984 goto immediate_exit; 985 } 986 987 mirror_free_init(s); 988 989 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 990 if (!s->is_none_mode) { 991 ret = mirror_dirty_init(s); 992 if (ret < 0 || job_is_cancelled(&s->common.job)) { 993 goto immediate_exit; 994 } 995 } 996 997 /* 998 * Only now the job is fully initialised and mirror_top_bs should start 999 * accessing it. 1000 */ 1001 mirror_top_opaque->job = s; 1002 1003 assert(!s->dbi); 1004 s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap); 1005 for (;;) { 1006 uint64_t delay_ns = 0; 1007 int64_t cnt, delta; 1008 bool should_complete; 1009 1010 if (s->ret < 0) { 1011 ret = s->ret; 1012 goto immediate_exit; 1013 } 1014 1015 job_pause_point(&s->common.job); 1016 1017 if (job_is_cancelled(&s->common.job)) { 1018 ret = 0; 1019 goto immediate_exit; 1020 } 1021 1022 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1023 /* cnt is the number of dirty bytes remaining and s->bytes_in_flight is 1024 * the number of bytes currently being processed; together those are 1025 * the current remaining operation length */ 1026 job_progress_set_remaining(&s->common.job, 1027 s->bytes_in_flight + cnt + 1028 s->active_write_bytes_in_flight); 1029 1030 /* Note that even when no rate limit is applied we need to yield 1031 * periodically with no pending I/O so that bdrv_drain_all() returns. 1032 * We do so every BLKOCK_JOB_SLICE_TIME nanoseconds, or when there is 1033 * an error, or when the source is clean, whichever comes first. */ 1034 delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns; 1035 WITH_JOB_LOCK_GUARD() { 1036 iostatus = s->common.iostatus; 1037 } 1038 if (delta < BLOCK_JOB_SLICE_TIME && 1039 iostatus == BLOCK_DEVICE_IO_STATUS_OK) { 1040 if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || 1041 (cnt == 0 && s->in_flight > 0)) { 1042 trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight); 1043 mirror_wait_for_free_in_flight_slot(s); 1044 continue; 1045 } else if (cnt != 0) { 1046 delay_ns = mirror_iteration(s); 1047 } 1048 } 1049 1050 should_complete = false; 1051 if (s->in_flight == 0 && cnt == 0) { 1052 trace_mirror_before_flush(s); 1053 if (!job_is_ready(&s->common.job)) { 1054 if (mirror_flush(s) < 0) { 1055 /* Go check s->ret. */ 1056 continue; 1057 } 1058 /* We're out of the streaming phase. From now on, if the job 1059 * is cancelled we will actually complete all pending I/O and 1060 * report completion. This way, block-job-cancel will leave 1061 * the target in a consistent state. 1062 */ 1063 job_transition_to_ready(&s->common.job); 1064 if (s->copy_mode != MIRROR_COPY_MODE_BACKGROUND) { 1065 s->actively_synced = true; 1066 } 1067 } 1068 1069 should_complete = s->should_complete || 1070 job_cancel_requested(&s->common.job); 1071 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1072 } 1073 1074 if (cnt == 0 && should_complete) { 1075 /* The dirty bitmap is not updated while operations are pending. 1076 * If we're about to exit, wait for pending operations before 1077 * calling bdrv_get_dirty_count(bs), or we may exit while the 1078 * source has dirty data to copy! 1079 * 1080 * Note that I/O can be submitted by the guest while 1081 * mirror_populate runs, so pause it now. Before deciding 1082 * whether to switch to target check one last time if I/O has 1083 * come in the meanwhile, and if not flush the data to disk. 1084 */ 1085 trace_mirror_before_drain(s, cnt); 1086 1087 s->in_drain = true; 1088 bdrv_drained_begin(bs); 1089 1090 /* Must be zero because we are drained */ 1091 assert(s->in_active_write_counter == 0); 1092 1093 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1094 if (cnt > 0 || mirror_flush(s) < 0) { 1095 bdrv_drained_end(bs); 1096 s->in_drain = false; 1097 continue; 1098 } 1099 1100 /* The two disks are in sync. Exit and report successful 1101 * completion. 1102 */ 1103 assert(QLIST_EMPTY(&bs->tracked_requests)); 1104 need_drain = false; 1105 break; 1106 } 1107 1108 if (job_is_ready(&s->common.job) && !should_complete) { 1109 delay_ns = (s->in_flight == 0 && 1110 cnt == 0 ? BLOCK_JOB_SLICE_TIME : 0); 1111 } 1112 trace_mirror_before_sleep(s, cnt, job_is_ready(&s->common.job), 1113 delay_ns); 1114 job_sleep_ns(&s->common.job, delay_ns); 1115 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 1116 } 1117 1118 immediate_exit: 1119 if (s->in_flight > 0) { 1120 /* We get here only if something went wrong. Either the job failed, 1121 * or it was cancelled prematurely so that we do not guarantee that 1122 * the target is a copy of the source. 1123 */ 1124 assert(ret < 0 || job_is_cancelled(&s->common.job)); 1125 assert(need_drain); 1126 mirror_wait_for_all_io(s); 1127 } 1128 1129 assert(s->in_flight == 0); 1130 qemu_vfree(s->buf); 1131 g_free(s->cow_bitmap); 1132 g_free(s->in_flight_bitmap); 1133 bdrv_dirty_iter_free(s->dbi); 1134 1135 if (need_drain) { 1136 s->in_drain = true; 1137 bdrv_drained_begin(bs); 1138 } 1139 1140 return ret; 1141 } 1142 1143 static void mirror_complete(Job *job, Error **errp) 1144 { 1145 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1146 1147 if (!job_is_ready(job)) { 1148 error_setg(errp, "The active block job '%s' cannot be completed", 1149 job->id); 1150 return; 1151 } 1152 1153 /* block all operations on to_replace bs */ 1154 if (s->replaces) { 1155 AioContext *replace_aio_context; 1156 1157 s->to_replace = bdrv_find_node(s->replaces); 1158 if (!s->to_replace) { 1159 error_setg(errp, "Node name '%s' not found", s->replaces); 1160 return; 1161 } 1162 1163 replace_aio_context = bdrv_get_aio_context(s->to_replace); 1164 aio_context_acquire(replace_aio_context); 1165 1166 /* TODO Translate this into child freeze system. */ 1167 error_setg(&s->replace_blocker, 1168 "block device is in use by block-job-complete"); 1169 bdrv_op_block_all(s->to_replace, s->replace_blocker); 1170 bdrv_ref(s->to_replace); 1171 1172 aio_context_release(replace_aio_context); 1173 } 1174 1175 s->should_complete = true; 1176 1177 /* If the job is paused, it will be re-entered when it is resumed */ 1178 WITH_JOB_LOCK_GUARD() { 1179 if (!job->paused) { 1180 job_enter_cond_locked(job, NULL); 1181 } 1182 } 1183 } 1184 1185 static void coroutine_fn mirror_pause(Job *job) 1186 { 1187 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1188 1189 mirror_wait_for_all_io(s); 1190 } 1191 1192 static bool mirror_drained_poll(BlockJob *job) 1193 { 1194 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1195 1196 /* If the job isn't paused nor cancelled, we can't be sure that it won't 1197 * issue more requests. We make an exception if we've reached this point 1198 * from one of our own drain sections, to avoid a deadlock waiting for 1199 * ourselves. 1200 */ 1201 WITH_JOB_LOCK_GUARD() { 1202 if (!s->common.job.paused && !job_is_cancelled_locked(&job->job) 1203 && !s->in_drain) { 1204 return true; 1205 } 1206 } 1207 1208 return !!s->in_flight; 1209 } 1210 1211 static bool mirror_cancel(Job *job, bool force) 1212 { 1213 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1214 BlockDriverState *target = blk_bs(s->target); 1215 1216 /* 1217 * Before the job is READY, we treat any cancellation like a 1218 * force-cancellation. 1219 */ 1220 force = force || !job_is_ready(job); 1221 1222 if (force) { 1223 bdrv_cancel_in_flight(target); 1224 } 1225 return force; 1226 } 1227 1228 static bool commit_active_cancel(Job *job, bool force) 1229 { 1230 /* Same as above in mirror_cancel() */ 1231 return force || !job_is_ready(job); 1232 } 1233 1234 static const BlockJobDriver mirror_job_driver = { 1235 .job_driver = { 1236 .instance_size = sizeof(MirrorBlockJob), 1237 .job_type = JOB_TYPE_MIRROR, 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 = mirror_cancel, 1246 }, 1247 .drained_poll = mirror_drained_poll, 1248 }; 1249 1250 static const BlockJobDriver commit_active_job_driver = { 1251 .job_driver = { 1252 .instance_size = sizeof(MirrorBlockJob), 1253 .job_type = JOB_TYPE_COMMIT, 1254 .free = block_job_free, 1255 .user_resume = block_job_user_resume, 1256 .run = mirror_run, 1257 .prepare = mirror_prepare, 1258 .abort = mirror_abort, 1259 .pause = mirror_pause, 1260 .complete = mirror_complete, 1261 .cancel = commit_active_cancel, 1262 }, 1263 .drained_poll = mirror_drained_poll, 1264 }; 1265 1266 static void coroutine_fn 1267 do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, 1268 uint64_t offset, uint64_t bytes, 1269 QEMUIOVector *qiov, int flags) 1270 { 1271 int ret; 1272 size_t qiov_offset = 0; 1273 int64_t bitmap_offset, bitmap_end; 1274 1275 if (!QEMU_IS_ALIGNED(offset, job->granularity) && 1276 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset)) 1277 { 1278 /* 1279 * Dirty unaligned padding: ignore it. 1280 * 1281 * Reasoning: 1282 * 1. If we copy it, we can't reset corresponding bit in 1283 * dirty_bitmap as there may be some "dirty" bytes still not 1284 * copied. 1285 * 2. It's already dirty, so skipping it we don't diverge mirror 1286 * progress. 1287 * 1288 * Note, that because of this, guest write may have no contribution 1289 * into mirror converge, but that's not bad, as we have background 1290 * process of mirroring. If under some bad circumstances (high guest 1291 * IO load) background process starve, we will not converge anyway, 1292 * even if each write will contribute, as guest is not guaranteed to 1293 * rewrite the whole disk. 1294 */ 1295 qiov_offset = QEMU_ALIGN_UP(offset, job->granularity) - offset; 1296 if (bytes <= qiov_offset) { 1297 /* nothing to do after shrink */ 1298 return; 1299 } 1300 offset += qiov_offset; 1301 bytes -= qiov_offset; 1302 } 1303 1304 if (!QEMU_IS_ALIGNED(offset + bytes, job->granularity) && 1305 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset + bytes - 1)) 1306 { 1307 uint64_t tail = (offset + bytes) % job->granularity; 1308 1309 if (bytes <= tail) { 1310 /* nothing to do after shrink */ 1311 return; 1312 } 1313 bytes -= tail; 1314 } 1315 1316 /* 1317 * Tails are either clean or shrunk, so for bitmap resetting 1318 * we safely align the range down. 1319 */ 1320 bitmap_offset = QEMU_ALIGN_UP(offset, job->granularity); 1321 bitmap_end = QEMU_ALIGN_DOWN(offset + bytes, job->granularity); 1322 if (bitmap_offset < bitmap_end) { 1323 bdrv_reset_dirty_bitmap(job->dirty_bitmap, bitmap_offset, 1324 bitmap_end - bitmap_offset); 1325 } 1326 1327 job_progress_increase_remaining(&job->common.job, bytes); 1328 job->active_write_bytes_in_flight += bytes; 1329 1330 switch (method) { 1331 case MIRROR_METHOD_COPY: 1332 ret = blk_co_pwritev_part(job->target, offset, bytes, 1333 qiov, qiov_offset, flags); 1334 break; 1335 1336 case MIRROR_METHOD_ZERO: 1337 assert(!qiov); 1338 ret = blk_co_pwrite_zeroes(job->target, offset, bytes, flags); 1339 break; 1340 1341 case MIRROR_METHOD_DISCARD: 1342 assert(!qiov); 1343 ret = blk_co_pdiscard(job->target, offset, bytes); 1344 break; 1345 1346 default: 1347 abort(); 1348 } 1349 1350 job->active_write_bytes_in_flight -= bytes; 1351 if (ret >= 0) { 1352 job_progress_update(&job->common.job, bytes); 1353 } else { 1354 BlockErrorAction action; 1355 1356 /* 1357 * We failed, so we should mark dirty the whole area, aligned up. 1358 * Note that we don't care about shrunk tails if any: they were dirty 1359 * at function start, and they must be still dirty, as we've locked 1360 * the region for in-flight op. 1361 */ 1362 bitmap_offset = QEMU_ALIGN_DOWN(offset, job->granularity); 1363 bitmap_end = QEMU_ALIGN_UP(offset + bytes, job->granularity); 1364 bdrv_set_dirty_bitmap(job->dirty_bitmap, bitmap_offset, 1365 bitmap_end - bitmap_offset); 1366 job->actively_synced = false; 1367 1368 action = mirror_error_action(job, false, -ret); 1369 if (action == BLOCK_ERROR_ACTION_REPORT) { 1370 if (!job->ret) { 1371 job->ret = ret; 1372 } 1373 } 1374 } 1375 } 1376 1377 static MirrorOp *coroutine_fn active_write_prepare(MirrorBlockJob *s, 1378 uint64_t offset, 1379 uint64_t bytes) 1380 { 1381 MirrorOp *op; 1382 uint64_t start_chunk = offset / s->granularity; 1383 uint64_t end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 1384 1385 op = g_new(MirrorOp, 1); 1386 *op = (MirrorOp){ 1387 .s = s, 1388 .offset = offset, 1389 .bytes = bytes, 1390 .is_active_write = true, 1391 .is_in_flight = true, 1392 .co = qemu_coroutine_self(), 1393 }; 1394 qemu_co_queue_init(&op->waiting_requests); 1395 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 1396 1397 s->in_active_write_counter++; 1398 1399 /* 1400 * Wait for concurrent requests affecting the area. If there are already 1401 * running requests that are copying off now-to-be stale data in the area, 1402 * we must wait for them to finish before we begin writing fresh data to the 1403 * target so that the write operations appear in the correct order. 1404 * Note that background requests (see mirror_iteration()) in contrast only 1405 * wait for conflicting requests at the start of the dirty area, and then 1406 * (based on the in_flight_bitmap) truncate the area to copy so it will not 1407 * conflict with any requests beyond that. For active writes, however, we 1408 * cannot truncate that area. The request from our parent must be blocked 1409 * until the area is copied in full. Therefore, we must wait for the whole 1410 * area to become free of concurrent requests. 1411 */ 1412 mirror_wait_on_conflicts(op, s, offset, bytes); 1413 1414 bitmap_set(s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1415 1416 return op; 1417 } 1418 1419 static void coroutine_fn active_write_settle(MirrorOp *op) 1420 { 1421 uint64_t start_chunk = op->offset / op->s->granularity; 1422 uint64_t end_chunk = DIV_ROUND_UP(op->offset + op->bytes, 1423 op->s->granularity); 1424 1425 if (!--op->s->in_active_write_counter && op->s->actively_synced) { 1426 BdrvChild *source = op->s->mirror_top_bs->backing; 1427 1428 if (QLIST_FIRST(&source->bs->parents) == source && 1429 QLIST_NEXT(source, next_parent) == NULL) 1430 { 1431 /* Assert that we are back in sync once all active write 1432 * operations are settled. 1433 * Note that we can only assert this if the mirror node 1434 * is the source node's only parent. */ 1435 assert(!bdrv_get_dirty_count(op->s->dirty_bitmap)); 1436 } 1437 } 1438 bitmap_clear(op->s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1439 QTAILQ_REMOVE(&op->s->ops_in_flight, op, next); 1440 qemu_co_queue_restart_all(&op->waiting_requests); 1441 g_free(op); 1442 } 1443 1444 static int coroutine_fn GRAPH_RDLOCK 1445 bdrv_mirror_top_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes, 1446 QEMUIOVector *qiov, BdrvRequestFlags flags) 1447 { 1448 return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); 1449 } 1450 1451 static int coroutine_fn GRAPH_RDLOCK 1452 bdrv_mirror_top_do_write(BlockDriverState *bs, MirrorMethod method, 1453 uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, 1454 int flags) 1455 { 1456 MirrorOp *op = NULL; 1457 MirrorBDSOpaque *s = bs->opaque; 1458 int ret = 0; 1459 bool copy_to_target = false; 1460 1461 if (s->job) { 1462 copy_to_target = s->job->ret >= 0 && 1463 !job_is_cancelled(&s->job->common.job) && 1464 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING; 1465 } 1466 1467 if (copy_to_target) { 1468 op = active_write_prepare(s->job, offset, bytes); 1469 } 1470 1471 switch (method) { 1472 case MIRROR_METHOD_COPY: 1473 ret = bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags); 1474 break; 1475 1476 case MIRROR_METHOD_ZERO: 1477 ret = bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags); 1478 break; 1479 1480 case MIRROR_METHOD_DISCARD: 1481 ret = bdrv_co_pdiscard(bs->backing, offset, bytes); 1482 break; 1483 1484 default: 1485 abort(); 1486 } 1487 1488 if (ret < 0) { 1489 goto out; 1490 } 1491 1492 if (copy_to_target) { 1493 do_sync_target_write(s->job, method, offset, bytes, qiov, flags); 1494 } 1495 1496 out: 1497 if (copy_to_target) { 1498 active_write_settle(op); 1499 } 1500 return ret; 1501 } 1502 1503 static int coroutine_fn GRAPH_RDLOCK 1504 bdrv_mirror_top_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes, 1505 QEMUIOVector *qiov, BdrvRequestFlags flags) 1506 { 1507 MirrorBDSOpaque *s = bs->opaque; 1508 QEMUIOVector bounce_qiov; 1509 void *bounce_buf; 1510 int ret = 0; 1511 bool copy_to_target = false; 1512 1513 if (s->job) { 1514 copy_to_target = s->job->ret >= 0 && 1515 !job_is_cancelled(&s->job->common.job) && 1516 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING; 1517 } 1518 1519 if (copy_to_target) { 1520 /* The guest might concurrently modify the data to write; but 1521 * the data on source and destination must match, so we have 1522 * to use a bounce buffer if we are going to write to the 1523 * target now. */ 1524 bounce_buf = qemu_blockalign(bs, bytes); 1525 iov_to_buf_full(qiov->iov, qiov->niov, 0, bounce_buf, bytes); 1526 1527 qemu_iovec_init(&bounce_qiov, 1); 1528 qemu_iovec_add(&bounce_qiov, bounce_buf, bytes); 1529 qiov = &bounce_qiov; 1530 1531 flags &= ~BDRV_REQ_REGISTERED_BUF; 1532 } 1533 1534 ret = bdrv_mirror_top_do_write(bs, MIRROR_METHOD_COPY, offset, bytes, qiov, 1535 flags); 1536 1537 if (copy_to_target) { 1538 qemu_iovec_destroy(&bounce_qiov); 1539 qemu_vfree(bounce_buf); 1540 } 1541 1542 return ret; 1543 } 1544 1545 static int coroutine_fn GRAPH_RDLOCK bdrv_mirror_top_flush(BlockDriverState *bs) 1546 { 1547 if (bs->backing == NULL) { 1548 /* we can be here after failed bdrv_append in mirror_start_job */ 1549 return 0; 1550 } 1551 return bdrv_co_flush(bs->backing->bs); 1552 } 1553 1554 static int coroutine_fn GRAPH_RDLOCK 1555 bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs, int64_t offset, 1556 int64_t bytes, BdrvRequestFlags flags) 1557 { 1558 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_ZERO, offset, bytes, NULL, 1559 flags); 1560 } 1561 1562 static int coroutine_fn GRAPH_RDLOCK 1563 bdrv_mirror_top_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes) 1564 { 1565 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_DISCARD, offset, bytes, 1566 NULL, 0); 1567 } 1568 1569 static void bdrv_mirror_top_refresh_filename(BlockDriverState *bs) 1570 { 1571 if (bs->backing == NULL) { 1572 /* we can be here after failed bdrv_attach_child in 1573 * bdrv_set_backing_hd */ 1574 return; 1575 } 1576 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), 1577 bs->backing->bs->filename); 1578 } 1579 1580 static void bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c, 1581 BdrvChildRole role, 1582 BlockReopenQueue *reopen_queue, 1583 uint64_t perm, uint64_t shared, 1584 uint64_t *nperm, uint64_t *nshared) 1585 { 1586 MirrorBDSOpaque *s = bs->opaque; 1587 1588 if (s->stop) { 1589 /* 1590 * If the job is to be stopped, we do not need to forward 1591 * anything to the real image. 1592 */ 1593 *nperm = 0; 1594 *nshared = BLK_PERM_ALL; 1595 return; 1596 } 1597 1598 bdrv_default_perms(bs, c, role, reopen_queue, 1599 perm, shared, nperm, nshared); 1600 1601 if (s->is_commit) { 1602 /* 1603 * For commit jobs, we cannot take CONSISTENT_READ, because 1604 * that permission is unshared for everything above the base 1605 * node (except for filters on the base node). 1606 * We also have to force-share the WRITE permission, or 1607 * otherwise we would block ourselves at the base node (if 1608 * writes are blocked for a node, they are also blocked for 1609 * its backing file). 1610 * (We could also share RESIZE, because it may be needed for 1611 * the target if its size is less than the top node's; but 1612 * bdrv_default_perms_for_cow() automatically shares RESIZE 1613 * for backing nodes if WRITE is shared, so there is no need 1614 * to do it here.) 1615 */ 1616 *nperm &= ~BLK_PERM_CONSISTENT_READ; 1617 *nshared |= BLK_PERM_WRITE; 1618 } 1619 } 1620 1621 /* Dummy node that provides consistent read to its users without requiring it 1622 * from its backing file and that allows writes on the backing file chain. */ 1623 static BlockDriver bdrv_mirror_top = { 1624 .format_name = "mirror_top", 1625 .bdrv_co_preadv = bdrv_mirror_top_preadv, 1626 .bdrv_co_pwritev = bdrv_mirror_top_pwritev, 1627 .bdrv_co_pwrite_zeroes = bdrv_mirror_top_pwrite_zeroes, 1628 .bdrv_co_pdiscard = bdrv_mirror_top_pdiscard, 1629 .bdrv_co_flush = bdrv_mirror_top_flush, 1630 .bdrv_refresh_filename = bdrv_mirror_top_refresh_filename, 1631 .bdrv_child_perm = bdrv_mirror_top_child_perm, 1632 1633 .is_filter = true, 1634 .filtered_child_is_backing = true, 1635 }; 1636 1637 static BlockJob *mirror_start_job( 1638 const char *job_id, BlockDriverState *bs, 1639 int creation_flags, BlockDriverState *target, 1640 const char *replaces, int64_t speed, 1641 uint32_t granularity, int64_t buf_size, 1642 BlockMirrorBackingMode backing_mode, 1643 bool zero_target, 1644 BlockdevOnError on_source_error, 1645 BlockdevOnError on_target_error, 1646 bool unmap, 1647 BlockCompletionFunc *cb, 1648 void *opaque, 1649 const BlockJobDriver *driver, 1650 bool is_none_mode, BlockDriverState *base, 1651 bool auto_complete, const char *filter_node_name, 1652 bool is_mirror, MirrorCopyMode copy_mode, 1653 Error **errp) 1654 { 1655 MirrorBlockJob *s; 1656 MirrorBDSOpaque *bs_opaque; 1657 BlockDriverState *mirror_top_bs; 1658 bool target_is_backing; 1659 uint64_t target_perms, target_shared_perms; 1660 int ret; 1661 1662 if (granularity == 0) { 1663 granularity = bdrv_get_default_bitmap_granularity(target); 1664 } 1665 1666 assert(is_power_of_2(granularity)); 1667 1668 if (buf_size < 0) { 1669 error_setg(errp, "Invalid parameter 'buf-size'"); 1670 return NULL; 1671 } 1672 1673 if (buf_size == 0) { 1674 buf_size = DEFAULT_MIRROR_BUF_SIZE; 1675 } 1676 1677 if (bdrv_skip_filters(bs) == bdrv_skip_filters(target)) { 1678 error_setg(errp, "Can't mirror node into itself"); 1679 return NULL; 1680 } 1681 1682 target_is_backing = bdrv_chain_contains(bs, target); 1683 1684 /* In the case of active commit, add dummy driver to provide consistent 1685 * reads on the top, while disabling it in the intermediate nodes, and make 1686 * the backing chain writable. */ 1687 mirror_top_bs = bdrv_new_open_driver(&bdrv_mirror_top, filter_node_name, 1688 BDRV_O_RDWR, errp); 1689 if (mirror_top_bs == NULL) { 1690 return NULL; 1691 } 1692 if (!filter_node_name) { 1693 mirror_top_bs->implicit = true; 1694 } 1695 1696 /* So that we can always drop this node */ 1697 mirror_top_bs->never_freeze = true; 1698 1699 mirror_top_bs->total_sectors = bs->total_sectors; 1700 mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED; 1701 mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED | 1702 BDRV_REQ_NO_FALLBACK; 1703 bs_opaque = g_new0(MirrorBDSOpaque, 1); 1704 mirror_top_bs->opaque = bs_opaque; 1705 1706 bs_opaque->is_commit = target_is_backing; 1707 1708 bdrv_drained_begin(bs); 1709 ret = bdrv_append(mirror_top_bs, bs, errp); 1710 bdrv_drained_end(bs); 1711 1712 if (ret < 0) { 1713 bdrv_unref(mirror_top_bs); 1714 return NULL; 1715 } 1716 1717 /* Make sure that the source is not resized while the job is running */ 1718 s = block_job_create(job_id, driver, NULL, mirror_top_bs, 1719 BLK_PERM_CONSISTENT_READ, 1720 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | 1721 BLK_PERM_WRITE, speed, 1722 creation_flags, cb, opaque, errp); 1723 if (!s) { 1724 goto fail; 1725 } 1726 1727 /* The block job now has a reference to this node */ 1728 bdrv_unref(mirror_top_bs); 1729 1730 s->mirror_top_bs = mirror_top_bs; 1731 1732 /* No resize for the target either; while the mirror is still running, a 1733 * consistent read isn't necessarily possible. We could possibly allow 1734 * writes and graph modifications, though it would likely defeat the 1735 * purpose of a mirror, so leave them blocked for now. 1736 * 1737 * In the case of active commit, things look a bit different, though, 1738 * because the target is an already populated backing file in active use. 1739 * We can allow anything except resize there.*/ 1740 1741 target_perms = BLK_PERM_WRITE; 1742 target_shared_perms = BLK_PERM_WRITE_UNCHANGED; 1743 1744 if (target_is_backing) { 1745 int64_t bs_size, target_size; 1746 bs_size = bdrv_getlength(bs); 1747 if (bs_size < 0) { 1748 error_setg_errno(errp, -bs_size, 1749 "Could not inquire top image size"); 1750 goto fail; 1751 } 1752 1753 target_size = bdrv_getlength(target); 1754 if (target_size < 0) { 1755 error_setg_errno(errp, -target_size, 1756 "Could not inquire base image size"); 1757 goto fail; 1758 } 1759 1760 if (target_size < bs_size) { 1761 target_perms |= BLK_PERM_RESIZE; 1762 } 1763 1764 target_shared_perms |= BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE; 1765 } else if (bdrv_chain_contains(bs, bdrv_skip_filters(target))) { 1766 /* 1767 * We may want to allow this in the future, but it would 1768 * require taking some extra care. 1769 */ 1770 error_setg(errp, "Cannot mirror to a filter on top of a node in the " 1771 "source's backing chain"); 1772 goto fail; 1773 } 1774 1775 s->target = blk_new(s->common.job.aio_context, 1776 target_perms, target_shared_perms); 1777 ret = blk_insert_bs(s->target, target, errp); 1778 if (ret < 0) { 1779 goto fail; 1780 } 1781 if (is_mirror) { 1782 /* XXX: Mirror target could be a NBD server of target QEMU in the case 1783 * of non-shared block migration. To allow migration completion, we 1784 * have to allow "inactivate" of the target BB. When that happens, we 1785 * know the job is drained, and the vcpus are stopped, so no write 1786 * operation will be performed. Block layer already has assertions to 1787 * ensure that. */ 1788 blk_set_force_allow_inactivate(s->target); 1789 } 1790 blk_set_allow_aio_context_change(s->target, true); 1791 blk_set_disable_request_queuing(s->target, true); 1792 1793 s->replaces = g_strdup(replaces); 1794 s->on_source_error = on_source_error; 1795 s->on_target_error = on_target_error; 1796 s->is_none_mode = is_none_mode; 1797 s->backing_mode = backing_mode; 1798 s->zero_target = zero_target; 1799 s->copy_mode = copy_mode; 1800 s->base = base; 1801 s->base_overlay = bdrv_find_overlay(bs, base); 1802 s->granularity = granularity; 1803 s->buf_size = ROUND_UP(buf_size, granularity); 1804 s->unmap = unmap; 1805 if (auto_complete) { 1806 s->should_complete = true; 1807 } 1808 1809 s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp); 1810 if (!s->dirty_bitmap) { 1811 goto fail; 1812 } 1813 if (s->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING) { 1814 bdrv_disable_dirty_bitmap(s->dirty_bitmap); 1815 } 1816 1817 ret = block_job_add_bdrv(&s->common, "source", bs, 0, 1818 BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE | 1819 BLK_PERM_CONSISTENT_READ, 1820 errp); 1821 if (ret < 0) { 1822 goto fail; 1823 } 1824 1825 /* Required permissions are already taken with blk_new() */ 1826 block_job_add_bdrv(&s->common, "target", target, 0, BLK_PERM_ALL, 1827 &error_abort); 1828 1829 /* In commit_active_start() all intermediate nodes disappear, so 1830 * any jobs in them must be blocked */ 1831 if (target_is_backing) { 1832 BlockDriverState *iter, *filtered_target; 1833 uint64_t iter_shared_perms; 1834 1835 /* 1836 * The topmost node with 1837 * bdrv_skip_filters(filtered_target) == bdrv_skip_filters(target) 1838 */ 1839 filtered_target = bdrv_cow_bs(bdrv_find_overlay(bs, target)); 1840 1841 assert(bdrv_skip_filters(filtered_target) == 1842 bdrv_skip_filters(target)); 1843 1844 /* 1845 * XXX BLK_PERM_WRITE needs to be allowed so we don't block 1846 * ourselves at s->base (if writes are blocked for a node, they are 1847 * also blocked for its backing file). The other options would be a 1848 * second filter driver above s->base (== target). 1849 */ 1850 iter_shared_perms = BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE; 1851 1852 for (iter = bdrv_filter_or_cow_bs(bs); iter != target; 1853 iter = bdrv_filter_or_cow_bs(iter)) 1854 { 1855 if (iter == filtered_target) { 1856 /* 1857 * From here on, all nodes are filters on the base. 1858 * This allows us to share BLK_PERM_CONSISTENT_READ. 1859 */ 1860 iter_shared_perms |= BLK_PERM_CONSISTENT_READ; 1861 } 1862 1863 ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, 1864 iter_shared_perms, errp); 1865 if (ret < 0) { 1866 goto fail; 1867 } 1868 } 1869 1870 if (bdrv_freeze_backing_chain(mirror_top_bs, target, errp) < 0) { 1871 goto fail; 1872 } 1873 } 1874 1875 QTAILQ_INIT(&s->ops_in_flight); 1876 1877 trace_mirror_start(bs, s, opaque); 1878 job_start(&s->common.job); 1879 1880 return &s->common; 1881 1882 fail: 1883 if (s) { 1884 /* Make sure this BDS does not go away until we have completed the graph 1885 * changes below */ 1886 bdrv_ref(mirror_top_bs); 1887 1888 g_free(s->replaces); 1889 blk_unref(s->target); 1890 bs_opaque->job = NULL; 1891 if (s->dirty_bitmap) { 1892 bdrv_release_dirty_bitmap(s->dirty_bitmap); 1893 } 1894 job_early_fail(&s->common.job); 1895 } 1896 1897 bs_opaque->stop = true; 1898 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 1899 &error_abort); 1900 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort); 1901 1902 bdrv_unref(mirror_top_bs); 1903 1904 return NULL; 1905 } 1906 1907 void mirror_start(const char *job_id, BlockDriverState *bs, 1908 BlockDriverState *target, const char *replaces, 1909 int creation_flags, int64_t speed, 1910 uint32_t granularity, int64_t buf_size, 1911 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, 1912 bool zero_target, 1913 BlockdevOnError on_source_error, 1914 BlockdevOnError on_target_error, 1915 bool unmap, const char *filter_node_name, 1916 MirrorCopyMode copy_mode, Error **errp) 1917 { 1918 bool is_none_mode; 1919 BlockDriverState *base; 1920 1921 GLOBAL_STATE_CODE(); 1922 1923 if ((mode == MIRROR_SYNC_MODE_INCREMENTAL) || 1924 (mode == MIRROR_SYNC_MODE_BITMAP)) { 1925 error_setg(errp, "Sync mode '%s' not supported", 1926 MirrorSyncMode_str(mode)); 1927 return; 1928 } 1929 is_none_mode = mode == MIRROR_SYNC_MODE_NONE; 1930 base = mode == MIRROR_SYNC_MODE_TOP ? bdrv_backing_chain_next(bs) : NULL; 1931 mirror_start_job(job_id, bs, creation_flags, target, replaces, 1932 speed, granularity, buf_size, backing_mode, zero_target, 1933 on_source_error, on_target_error, unmap, NULL, NULL, 1934 &mirror_job_driver, is_none_mode, base, false, 1935 filter_node_name, true, copy_mode, errp); 1936 } 1937 1938 BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs, 1939 BlockDriverState *base, int creation_flags, 1940 int64_t speed, BlockdevOnError on_error, 1941 const char *filter_node_name, 1942 BlockCompletionFunc *cb, void *opaque, 1943 bool auto_complete, Error **errp) 1944 { 1945 bool base_read_only; 1946 BlockJob *job; 1947 1948 GLOBAL_STATE_CODE(); 1949 1950 base_read_only = bdrv_is_read_only(base); 1951 1952 if (base_read_only) { 1953 if (bdrv_reopen_set_read_only(base, false, errp) < 0) { 1954 return NULL; 1955 } 1956 } 1957 1958 job = mirror_start_job( 1959 job_id, bs, creation_flags, base, NULL, speed, 0, 0, 1960 MIRROR_LEAVE_BACKING_CHAIN, false, 1961 on_error, on_error, true, cb, opaque, 1962 &commit_active_job_driver, false, base, auto_complete, 1963 filter_node_name, false, MIRROR_COPY_MODE_BACKGROUND, 1964 errp); 1965 if (!job) { 1966 goto error_restore_flags; 1967 } 1968 1969 return job; 1970 1971 error_restore_flags: 1972 /* ignore error and errp for bdrv_reopen, because we want to propagate 1973 * the original error */ 1974 if (base_read_only) { 1975 bdrv_reopen_set_read_only(base, true, NULL); 1976 } 1977 return NULL; 1978 } 1979