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 coroutine_fn 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 void 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 /* 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 WITH_GRAPH_RDLOCK_GUARD() { 562 ret = bdrv_block_status_above(source, NULL, offset, 563 nb_chunks * s->granularity, 564 &io_bytes, NULL, NULL); 565 } 566 if (ret < 0) { 567 io_bytes = MIN(nb_chunks * s->granularity, max_io_bytes); 568 } else if (ret & BDRV_BLOCK_DATA) { 569 io_bytes = MIN(io_bytes, max_io_bytes); 570 } 571 572 io_bytes -= io_bytes % s->granularity; 573 if (io_bytes < s->granularity) { 574 io_bytes = s->granularity; 575 } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) { 576 int64_t target_offset; 577 int64_t target_bytes; 578 WITH_GRAPH_RDLOCK_GUARD() { 579 bdrv_round_to_clusters(blk_bs(s->target), offset, io_bytes, 580 &target_offset, &target_bytes); 581 } 582 if (target_offset == offset && 583 target_bytes == io_bytes) { 584 mirror_method = ret & BDRV_BLOCK_ZERO ? 585 MIRROR_METHOD_ZERO : 586 MIRROR_METHOD_DISCARD; 587 } 588 } 589 590 while (s->in_flight >= MAX_IN_FLIGHT) { 591 trace_mirror_yield_in_flight(s, offset, s->in_flight); 592 mirror_wait_for_free_in_flight_slot(s); 593 } 594 595 if (s->ret < 0) { 596 ret = 0; 597 goto fail; 598 } 599 600 io_bytes = mirror_clip_bytes(s, offset, io_bytes); 601 io_bytes = mirror_perform(s, offset, io_bytes, mirror_method); 602 if (mirror_method != MIRROR_METHOD_COPY && write_zeroes_ok) { 603 io_bytes_acct = 0; 604 } else { 605 io_bytes_acct = io_bytes; 606 } 607 assert(io_bytes); 608 offset += io_bytes; 609 nb_chunks -= DIV_ROUND_UP(io_bytes, s->granularity); 610 block_job_ratelimit_processed_bytes(&s->common, io_bytes_acct); 611 } 612 613 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 } 618 619 static void mirror_free_init(MirrorBlockJob *s) 620 { 621 int granularity = s->granularity; 622 size_t buf_size = s->buf_size; 623 uint8_t *buf = s->buf; 624 625 assert(s->buf_free_count == 0); 626 QSIMPLEQ_INIT(&s->buf_free); 627 while (buf_size != 0) { 628 MirrorBuffer *cur = (MirrorBuffer *)buf; 629 QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); 630 s->buf_free_count++; 631 buf_size -= granularity; 632 buf += granularity; 633 } 634 } 635 636 /* This is also used for the .pause callback. There is no matching 637 * mirror_resume() because mirror_run() will begin iterating again 638 * when the job is resumed. 639 */ 640 static void coroutine_fn mirror_wait_for_all_io(MirrorBlockJob *s) 641 { 642 while (s->in_flight > 0) { 643 mirror_wait_for_free_in_flight_slot(s); 644 } 645 } 646 647 /** 648 * mirror_exit_common: handle both abort() and prepare() cases. 649 * for .prepare, returns 0 on success and -errno on failure. 650 * for .abort cases, denoted by abort = true, MUST return 0. 651 */ 652 static int mirror_exit_common(Job *job) 653 { 654 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 655 BlockJob *bjob = &s->common; 656 MirrorBDSOpaque *bs_opaque; 657 AioContext *replace_aio_context = NULL; 658 BlockDriverState *src; 659 BlockDriverState *target_bs; 660 BlockDriverState *mirror_top_bs; 661 Error *local_err = NULL; 662 bool abort = job->ret < 0; 663 int ret = 0; 664 665 if (s->prepared) { 666 return 0; 667 } 668 s->prepared = true; 669 670 mirror_top_bs = s->mirror_top_bs; 671 bs_opaque = mirror_top_bs->opaque; 672 src = mirror_top_bs->backing->bs; 673 target_bs = blk_bs(s->target); 674 675 if (bdrv_chain_contains(src, target_bs)) { 676 bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs); 677 } 678 679 bdrv_release_dirty_bitmap(s->dirty_bitmap); 680 681 /* Make sure that the source BDS doesn't go away during bdrv_replace_node, 682 * before we can call bdrv_drained_end */ 683 bdrv_ref(src); 684 bdrv_ref(mirror_top_bs); 685 bdrv_ref(target_bs); 686 687 /* 688 * Remove target parent that still uses BLK_PERM_WRITE/RESIZE before 689 * inserting target_bs at s->to_replace, where we might not be able to get 690 * these permissions. 691 */ 692 blk_unref(s->target); 693 s->target = NULL; 694 695 /* We don't access the source any more. Dropping any WRITE/RESIZE is 696 * required before it could become a backing file of target_bs. Not having 697 * these permissions any more means that we can't allow any new requests on 698 * mirror_top_bs from now on, so keep it drained. */ 699 bdrv_drained_begin(mirror_top_bs); 700 bs_opaque->stop = true; 701 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 702 &error_abort); 703 if (!abort && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { 704 BlockDriverState *backing = s->is_none_mode ? src : s->base; 705 BlockDriverState *unfiltered_target = bdrv_skip_filters(target_bs); 706 707 if (bdrv_cow_bs(unfiltered_target) != backing) { 708 bdrv_set_backing_hd(unfiltered_target, backing, &local_err); 709 if (local_err) { 710 error_report_err(local_err); 711 local_err = NULL; 712 ret = -EPERM; 713 } 714 } 715 } else if (!abort && s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { 716 assert(!bdrv_backing_chain_next(target_bs)); 717 ret = bdrv_open_backing_file(bdrv_skip_filters(target_bs), NULL, 718 "backing", &local_err); 719 if (ret < 0) { 720 error_report_err(local_err); 721 local_err = NULL; 722 } 723 } 724 725 if (s->to_replace) { 726 replace_aio_context = bdrv_get_aio_context(s->to_replace); 727 aio_context_acquire(replace_aio_context); 728 } 729 730 if (s->should_complete && !abort) { 731 BlockDriverState *to_replace = s->to_replace ?: src; 732 bool ro = bdrv_is_read_only(to_replace); 733 734 if (ro != bdrv_is_read_only(target_bs)) { 735 bdrv_reopen_set_read_only(target_bs, ro, NULL); 736 } 737 738 /* The mirror job has no requests in flight any more, but we need to 739 * drain potential other users of the BDS before changing the graph. */ 740 assert(s->in_drain); 741 bdrv_drained_begin(target_bs); 742 /* 743 * Cannot use check_to_replace_node() here, because that would 744 * check for an op blocker on @to_replace, and we have our own 745 * there. 746 * 747 * TODO Pull out the writer lock from bdrv_replace_node() to here 748 */ 749 bdrv_graph_rdlock_main_loop(); 750 if (bdrv_recurse_can_replace(src, to_replace)) { 751 bdrv_replace_node(to_replace, target_bs, &local_err); 752 } else { 753 error_setg(&local_err, "Can no longer replace '%s' by '%s', " 754 "because it can no longer be guaranteed that doing so " 755 "would not lead to an abrupt change of visible data", 756 to_replace->node_name, target_bs->node_name); 757 } 758 bdrv_graph_rdunlock_main_loop(); 759 bdrv_drained_end(target_bs); 760 if (local_err) { 761 error_report_err(local_err); 762 ret = -EPERM; 763 } 764 } 765 if (s->to_replace) { 766 bdrv_op_unblock_all(s->to_replace, s->replace_blocker); 767 error_free(s->replace_blocker); 768 bdrv_unref(s->to_replace); 769 } 770 if (replace_aio_context) { 771 aio_context_release(replace_aio_context); 772 } 773 g_free(s->replaces); 774 bdrv_unref(target_bs); 775 776 /* 777 * Remove the mirror filter driver from the graph. Before this, get rid of 778 * the blockers on the intermediate nodes so that the resulting state is 779 * valid. 780 */ 781 block_job_remove_all_bdrv(bjob); 782 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort); 783 784 bs_opaque->job = NULL; 785 786 bdrv_drained_end(src); 787 bdrv_drained_end(mirror_top_bs); 788 s->in_drain = false; 789 bdrv_unref(mirror_top_bs); 790 bdrv_unref(src); 791 792 return ret; 793 } 794 795 static int mirror_prepare(Job *job) 796 { 797 return mirror_exit_common(job); 798 } 799 800 static void mirror_abort(Job *job) 801 { 802 int ret = mirror_exit_common(job); 803 assert(ret == 0); 804 } 805 806 static void coroutine_fn mirror_throttle(MirrorBlockJob *s) 807 { 808 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 809 810 if (now - s->last_pause_ns > BLOCK_JOB_SLICE_TIME) { 811 s->last_pause_ns = now; 812 job_sleep_ns(&s->common.job, 0); 813 } else { 814 job_pause_point(&s->common.job); 815 } 816 } 817 818 static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) 819 { 820 int64_t offset; 821 BlockDriverState *bs = s->mirror_top_bs->backing->bs; 822 BlockDriverState *target_bs = blk_bs(s->target); 823 int ret; 824 int64_t count; 825 826 if (s->zero_target) { 827 if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { 828 bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length); 829 return 0; 830 } 831 832 s->initial_zeroing_ongoing = true; 833 for (offset = 0; offset < s->bdev_length; ) { 834 int bytes = MIN(s->bdev_length - offset, 835 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 836 837 mirror_throttle(s); 838 839 if (job_is_cancelled(&s->common.job)) { 840 s->initial_zeroing_ongoing = false; 841 return 0; 842 } 843 844 if (s->in_flight >= MAX_IN_FLIGHT) { 845 trace_mirror_yield(s, UINT64_MAX, s->buf_free_count, 846 s->in_flight); 847 mirror_wait_for_free_in_flight_slot(s); 848 continue; 849 } 850 851 mirror_perform(s, offset, bytes, MIRROR_METHOD_ZERO); 852 offset += bytes; 853 } 854 855 mirror_wait_for_all_io(s); 856 s->initial_zeroing_ongoing = false; 857 } 858 859 /* First part, loop on the sectors and initialize the dirty bitmap. */ 860 for (offset = 0; offset < s->bdev_length; ) { 861 /* Just to make sure we are not exceeding int limit. */ 862 int bytes = MIN(s->bdev_length - offset, 863 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 864 865 mirror_throttle(s); 866 867 if (job_is_cancelled(&s->common.job)) { 868 return 0; 869 } 870 871 WITH_GRAPH_RDLOCK_GUARD() { 872 ret = bdrv_is_allocated_above(bs, s->base_overlay, true, offset, 873 bytes, &count); 874 } 875 if (ret < 0) { 876 return ret; 877 } 878 879 assert(count); 880 if (ret > 0) { 881 bdrv_set_dirty_bitmap(s->dirty_bitmap, offset, count); 882 } 883 offset += count; 884 } 885 return 0; 886 } 887 888 /* Called when going out of the streaming phase to flush the bulk of the 889 * data to the medium, or just before completing. 890 */ 891 static int coroutine_fn mirror_flush(MirrorBlockJob *s) 892 { 893 int ret = blk_co_flush(s->target); 894 if (ret < 0) { 895 if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) { 896 s->ret = ret; 897 } 898 } 899 return ret; 900 } 901 902 static int coroutine_fn mirror_run(Job *job, Error **errp) 903 { 904 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 905 BlockDriverState *bs = s->mirror_top_bs->backing->bs; 906 MirrorBDSOpaque *mirror_top_opaque = s->mirror_top_bs->opaque; 907 BlockDriverState *target_bs = blk_bs(s->target); 908 bool need_drain = true; 909 BlockDeviceIoStatus iostatus; 910 int64_t length; 911 int64_t target_length; 912 BlockDriverInfo bdi; 913 char backing_filename[2]; /* we only need 2 characters because we are only 914 checking for a NULL string */ 915 int ret = 0; 916 917 if (job_is_cancelled(&s->common.job)) { 918 goto immediate_exit; 919 } 920 921 bdrv_graph_co_rdlock(); 922 s->bdev_length = bdrv_co_getlength(bs); 923 bdrv_graph_co_rdunlock(); 924 925 if (s->bdev_length < 0) { 926 ret = s->bdev_length; 927 goto immediate_exit; 928 } 929 930 target_length = blk_co_getlength(s->target); 931 if (target_length < 0) { 932 ret = target_length; 933 goto immediate_exit; 934 } 935 936 /* Active commit must resize the base image if its size differs from the 937 * active layer. */ 938 if (s->base == blk_bs(s->target)) { 939 if (s->bdev_length > target_length) { 940 ret = blk_co_truncate(s->target, s->bdev_length, false, 941 PREALLOC_MODE_OFF, 0, NULL); 942 if (ret < 0) { 943 goto immediate_exit; 944 } 945 } 946 } else if (s->bdev_length != target_length) { 947 error_setg(errp, "Source and target image have different sizes"); 948 ret = -EINVAL; 949 goto immediate_exit; 950 } 951 952 if (s->bdev_length == 0) { 953 /* Transition to the READY state and wait for complete. */ 954 job_transition_to_ready(&s->common.job); 955 s->actively_synced = true; 956 while (!job_cancel_requested(&s->common.job) && !s->should_complete) { 957 job_yield(&s->common.job); 958 } 959 goto immediate_exit; 960 } 961 962 length = DIV_ROUND_UP(s->bdev_length, s->granularity); 963 s->in_flight_bitmap = bitmap_new(length); 964 965 /* If we have no backing file yet in the destination, we cannot let 966 * the destination do COW. Instead, we copy sectors around the 967 * dirty data if needed. We need a bitmap to do that. 968 */ 969 bdrv_get_backing_filename(target_bs, backing_filename, 970 sizeof(backing_filename)); 971 bdrv_graph_co_rdlock(); 972 if (!bdrv_co_get_info(target_bs, &bdi) && bdi.cluster_size) { 973 s->target_cluster_size = bdi.cluster_size; 974 } else { 975 s->target_cluster_size = BDRV_SECTOR_SIZE; 976 } 977 bdrv_graph_co_rdunlock(); 978 if (backing_filename[0] && !bdrv_backing_chain_next(target_bs) && 979 s->granularity < s->target_cluster_size) { 980 s->buf_size = MAX(s->buf_size, s->target_cluster_size); 981 s->cow_bitmap = bitmap_new(length); 982 } 983 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); 984 985 s->buf = qemu_try_blockalign(bs, s->buf_size); 986 if (s->buf == NULL) { 987 ret = -ENOMEM; 988 goto immediate_exit; 989 } 990 991 mirror_free_init(s); 992 993 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 994 if (!s->is_none_mode) { 995 ret = mirror_dirty_init(s); 996 if (ret < 0 || job_is_cancelled(&s->common.job)) { 997 goto immediate_exit; 998 } 999 } 1000 1001 /* 1002 * Only now the job is fully initialised and mirror_top_bs should start 1003 * accessing it. 1004 */ 1005 mirror_top_opaque->job = s; 1006 1007 assert(!s->dbi); 1008 s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap); 1009 for (;;) { 1010 int64_t cnt, delta; 1011 bool should_complete; 1012 1013 if (s->ret < 0) { 1014 ret = s->ret; 1015 goto immediate_exit; 1016 } 1017 1018 job_pause_point(&s->common.job); 1019 1020 if (job_is_cancelled(&s->common.job)) { 1021 ret = 0; 1022 goto immediate_exit; 1023 } 1024 1025 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1026 /* cnt is the number of dirty bytes remaining and s->bytes_in_flight is 1027 * the number of bytes currently being processed; together those are 1028 * the current remaining operation length */ 1029 job_progress_set_remaining(&s->common.job, 1030 s->bytes_in_flight + cnt + 1031 s->active_write_bytes_in_flight); 1032 1033 /* Note that even when no rate limit is applied we need to yield 1034 * periodically with no pending I/O so that bdrv_drain_all() returns. 1035 * We do so every BLKOCK_JOB_SLICE_TIME nanoseconds, or when there is 1036 * an error, or when the source is clean, whichever comes first. */ 1037 delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns; 1038 WITH_JOB_LOCK_GUARD() { 1039 iostatus = s->common.iostatus; 1040 } 1041 if (delta < BLOCK_JOB_SLICE_TIME && 1042 iostatus == BLOCK_DEVICE_IO_STATUS_OK) { 1043 if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || 1044 (cnt == 0 && s->in_flight > 0)) { 1045 trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight); 1046 mirror_wait_for_free_in_flight_slot(s); 1047 continue; 1048 } else if (cnt != 0) { 1049 mirror_iteration(s); 1050 } 1051 } 1052 1053 should_complete = false; 1054 if (s->in_flight == 0 && cnt == 0) { 1055 trace_mirror_before_flush(s); 1056 if (!job_is_ready(&s->common.job)) { 1057 if (mirror_flush(s) < 0) { 1058 /* Go check s->ret. */ 1059 continue; 1060 } 1061 /* We're out of the streaming phase. From now on, if the job 1062 * is cancelled we will actually complete all pending I/O and 1063 * report completion. This way, block-job-cancel will leave 1064 * the target in a consistent state. 1065 */ 1066 job_transition_to_ready(&s->common.job); 1067 if (s->copy_mode != MIRROR_COPY_MODE_BACKGROUND) { 1068 s->actively_synced = true; 1069 } 1070 } 1071 1072 should_complete = s->should_complete || 1073 job_cancel_requested(&s->common.job); 1074 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1075 } 1076 1077 if (cnt == 0 && should_complete) { 1078 /* The dirty bitmap is not updated while operations are pending. 1079 * If we're about to exit, wait for pending operations before 1080 * calling bdrv_get_dirty_count(bs), or we may exit while the 1081 * source has dirty data to copy! 1082 * 1083 * Note that I/O can be submitted by the guest while 1084 * mirror_populate runs, so pause it now. Before deciding 1085 * whether to switch to target check one last time if I/O has 1086 * come in the meanwhile, and if not flush the data to disk. 1087 */ 1088 trace_mirror_before_drain(s, cnt); 1089 1090 s->in_drain = true; 1091 bdrv_drained_begin(bs); 1092 1093 /* Must be zero because we are drained */ 1094 assert(s->in_active_write_counter == 0); 1095 1096 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1097 if (cnt > 0 || mirror_flush(s) < 0) { 1098 bdrv_drained_end(bs); 1099 s->in_drain = false; 1100 continue; 1101 } 1102 1103 /* The two disks are in sync. Exit and report successful 1104 * completion. 1105 */ 1106 assert(QLIST_EMPTY(&bs->tracked_requests)); 1107 need_drain = false; 1108 break; 1109 } 1110 1111 if (job_is_ready(&s->common.job) && !should_complete) { 1112 if (s->in_flight == 0 && cnt == 0) { 1113 trace_mirror_before_sleep(s, cnt, job_is_ready(&s->common.job), 1114 BLOCK_JOB_SLICE_TIME); 1115 job_sleep_ns(&s->common.job, BLOCK_JOB_SLICE_TIME); 1116 } 1117 } else { 1118 block_job_ratelimit_sleep(&s->common); 1119 } 1120 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 1121 } 1122 1123 immediate_exit: 1124 if (s->in_flight > 0) { 1125 /* We get here only if something went wrong. Either the job failed, 1126 * or it was cancelled prematurely so that we do not guarantee that 1127 * the target is a copy of the source. 1128 */ 1129 assert(ret < 0 || job_is_cancelled(&s->common.job)); 1130 assert(need_drain); 1131 mirror_wait_for_all_io(s); 1132 } 1133 1134 assert(s->in_flight == 0); 1135 qemu_vfree(s->buf); 1136 g_free(s->cow_bitmap); 1137 g_free(s->in_flight_bitmap); 1138 bdrv_dirty_iter_free(s->dbi); 1139 1140 if (need_drain) { 1141 s->in_drain = true; 1142 bdrv_drained_begin(bs); 1143 } 1144 1145 return ret; 1146 } 1147 1148 static void mirror_complete(Job *job, Error **errp) 1149 { 1150 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1151 1152 if (!job_is_ready(job)) { 1153 error_setg(errp, "The active block job '%s' cannot be completed", 1154 job->id); 1155 return; 1156 } 1157 1158 /* block all operations on to_replace bs */ 1159 if (s->replaces) { 1160 AioContext *replace_aio_context; 1161 1162 s->to_replace = bdrv_find_node(s->replaces); 1163 if (!s->to_replace) { 1164 error_setg(errp, "Node name '%s' not found", s->replaces); 1165 return; 1166 } 1167 1168 replace_aio_context = bdrv_get_aio_context(s->to_replace); 1169 aio_context_acquire(replace_aio_context); 1170 1171 /* TODO Translate this into child freeze system. */ 1172 error_setg(&s->replace_blocker, 1173 "block device is in use by block-job-complete"); 1174 bdrv_op_block_all(s->to_replace, s->replace_blocker); 1175 bdrv_ref(s->to_replace); 1176 1177 aio_context_release(replace_aio_context); 1178 } 1179 1180 s->should_complete = true; 1181 1182 /* If the job is paused, it will be re-entered when it is resumed */ 1183 WITH_JOB_LOCK_GUARD() { 1184 if (!job->paused) { 1185 job_enter_cond_locked(job, NULL); 1186 } 1187 } 1188 } 1189 1190 static void coroutine_fn mirror_pause(Job *job) 1191 { 1192 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1193 1194 mirror_wait_for_all_io(s); 1195 } 1196 1197 static bool mirror_drained_poll(BlockJob *job) 1198 { 1199 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1200 1201 /* If the job isn't paused nor cancelled, we can't be sure that it won't 1202 * issue more requests. We make an exception if we've reached this point 1203 * from one of our own drain sections, to avoid a deadlock waiting for 1204 * ourselves. 1205 */ 1206 WITH_JOB_LOCK_GUARD() { 1207 if (!s->common.job.paused && !job_is_cancelled_locked(&job->job) 1208 && !s->in_drain) { 1209 return true; 1210 } 1211 } 1212 1213 return !!s->in_flight; 1214 } 1215 1216 static bool mirror_cancel(Job *job, bool force) 1217 { 1218 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1219 BlockDriverState *target = blk_bs(s->target); 1220 1221 /* 1222 * Before the job is READY, we treat any cancellation like a 1223 * force-cancellation. 1224 */ 1225 force = force || !job_is_ready(job); 1226 1227 if (force) { 1228 bdrv_cancel_in_flight(target); 1229 } 1230 return force; 1231 } 1232 1233 static bool commit_active_cancel(Job *job, bool force) 1234 { 1235 /* Same as above in mirror_cancel() */ 1236 return force || !job_is_ready(job); 1237 } 1238 1239 static const BlockJobDriver mirror_job_driver = { 1240 .job_driver = { 1241 .instance_size = sizeof(MirrorBlockJob), 1242 .job_type = JOB_TYPE_MIRROR, 1243 .free = block_job_free, 1244 .user_resume = block_job_user_resume, 1245 .run = mirror_run, 1246 .prepare = mirror_prepare, 1247 .abort = mirror_abort, 1248 .pause = mirror_pause, 1249 .complete = mirror_complete, 1250 .cancel = mirror_cancel, 1251 }, 1252 .drained_poll = mirror_drained_poll, 1253 }; 1254 1255 static const BlockJobDriver commit_active_job_driver = { 1256 .job_driver = { 1257 .instance_size = sizeof(MirrorBlockJob), 1258 .job_type = JOB_TYPE_COMMIT, 1259 .free = block_job_free, 1260 .user_resume = block_job_user_resume, 1261 .run = mirror_run, 1262 .prepare = mirror_prepare, 1263 .abort = mirror_abort, 1264 .pause = mirror_pause, 1265 .complete = mirror_complete, 1266 .cancel = commit_active_cancel, 1267 }, 1268 .drained_poll = mirror_drained_poll, 1269 }; 1270 1271 static void coroutine_fn 1272 do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, 1273 uint64_t offset, uint64_t bytes, 1274 QEMUIOVector *qiov, int flags) 1275 { 1276 int ret; 1277 size_t qiov_offset = 0; 1278 int64_t bitmap_offset, bitmap_end; 1279 1280 if (!QEMU_IS_ALIGNED(offset, job->granularity) && 1281 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset)) 1282 { 1283 /* 1284 * Dirty unaligned padding: ignore it. 1285 * 1286 * Reasoning: 1287 * 1. If we copy it, we can't reset corresponding bit in 1288 * dirty_bitmap as there may be some "dirty" bytes still not 1289 * copied. 1290 * 2. It's already dirty, so skipping it we don't diverge mirror 1291 * progress. 1292 * 1293 * Note, that because of this, guest write may have no contribution 1294 * into mirror converge, but that's not bad, as we have background 1295 * process of mirroring. If under some bad circumstances (high guest 1296 * IO load) background process starve, we will not converge anyway, 1297 * even if each write will contribute, as guest is not guaranteed to 1298 * rewrite the whole disk. 1299 */ 1300 qiov_offset = QEMU_ALIGN_UP(offset, job->granularity) - offset; 1301 if (bytes <= qiov_offset) { 1302 /* nothing to do after shrink */ 1303 return; 1304 } 1305 offset += qiov_offset; 1306 bytes -= qiov_offset; 1307 } 1308 1309 if (!QEMU_IS_ALIGNED(offset + bytes, job->granularity) && 1310 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset + bytes - 1)) 1311 { 1312 uint64_t tail = (offset + bytes) % job->granularity; 1313 1314 if (bytes <= tail) { 1315 /* nothing to do after shrink */ 1316 return; 1317 } 1318 bytes -= tail; 1319 } 1320 1321 /* 1322 * Tails are either clean or shrunk, so for bitmap resetting 1323 * we safely align the range down. 1324 */ 1325 bitmap_offset = QEMU_ALIGN_UP(offset, job->granularity); 1326 bitmap_end = QEMU_ALIGN_DOWN(offset + bytes, job->granularity); 1327 if (bitmap_offset < bitmap_end) { 1328 bdrv_reset_dirty_bitmap(job->dirty_bitmap, bitmap_offset, 1329 bitmap_end - bitmap_offset); 1330 } 1331 1332 job_progress_increase_remaining(&job->common.job, bytes); 1333 job->active_write_bytes_in_flight += bytes; 1334 1335 switch (method) { 1336 case MIRROR_METHOD_COPY: 1337 ret = blk_co_pwritev_part(job->target, offset, bytes, 1338 qiov, qiov_offset, flags); 1339 break; 1340 1341 case MIRROR_METHOD_ZERO: 1342 assert(!qiov); 1343 ret = blk_co_pwrite_zeroes(job->target, offset, bytes, flags); 1344 break; 1345 1346 case MIRROR_METHOD_DISCARD: 1347 assert(!qiov); 1348 ret = blk_co_pdiscard(job->target, offset, bytes); 1349 break; 1350 1351 default: 1352 abort(); 1353 } 1354 1355 job->active_write_bytes_in_flight -= bytes; 1356 if (ret >= 0) { 1357 job_progress_update(&job->common.job, bytes); 1358 } else { 1359 BlockErrorAction action; 1360 1361 /* 1362 * We failed, so we should mark dirty the whole area, aligned up. 1363 * Note that we don't care about shrunk tails if any: they were dirty 1364 * at function start, and they must be still dirty, as we've locked 1365 * the region for in-flight op. 1366 */ 1367 bitmap_offset = QEMU_ALIGN_DOWN(offset, job->granularity); 1368 bitmap_end = QEMU_ALIGN_UP(offset + bytes, job->granularity); 1369 bdrv_set_dirty_bitmap(job->dirty_bitmap, bitmap_offset, 1370 bitmap_end - bitmap_offset); 1371 job->actively_synced = false; 1372 1373 action = mirror_error_action(job, false, -ret); 1374 if (action == BLOCK_ERROR_ACTION_REPORT) { 1375 if (!job->ret) { 1376 job->ret = ret; 1377 } 1378 } 1379 } 1380 } 1381 1382 static MirrorOp *coroutine_fn active_write_prepare(MirrorBlockJob *s, 1383 uint64_t offset, 1384 uint64_t bytes) 1385 { 1386 MirrorOp *op; 1387 uint64_t start_chunk = offset / s->granularity; 1388 uint64_t end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 1389 1390 op = g_new(MirrorOp, 1); 1391 *op = (MirrorOp){ 1392 .s = s, 1393 .offset = offset, 1394 .bytes = bytes, 1395 .is_active_write = true, 1396 .is_in_flight = true, 1397 .co = qemu_coroutine_self(), 1398 }; 1399 qemu_co_queue_init(&op->waiting_requests); 1400 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 1401 1402 s->in_active_write_counter++; 1403 1404 /* 1405 * Wait for concurrent requests affecting the area. If there are already 1406 * running requests that are copying off now-to-be stale data in the area, 1407 * we must wait for them to finish before we begin writing fresh data to the 1408 * target so that the write operations appear in the correct order. 1409 * Note that background requests (see mirror_iteration()) in contrast only 1410 * wait for conflicting requests at the start of the dirty area, and then 1411 * (based on the in_flight_bitmap) truncate the area to copy so it will not 1412 * conflict with any requests beyond that. For active writes, however, we 1413 * cannot truncate that area. The request from our parent must be blocked 1414 * until the area is copied in full. Therefore, we must wait for the whole 1415 * area to become free of concurrent requests. 1416 */ 1417 mirror_wait_on_conflicts(op, s, offset, bytes); 1418 1419 bitmap_set(s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1420 1421 return op; 1422 } 1423 1424 static void coroutine_fn GRAPH_RDLOCK active_write_settle(MirrorOp *op) 1425 { 1426 uint64_t start_chunk = op->offset / op->s->granularity; 1427 uint64_t end_chunk = DIV_ROUND_UP(op->offset + op->bytes, 1428 op->s->granularity); 1429 1430 if (!--op->s->in_active_write_counter && op->s->actively_synced) { 1431 BdrvChild *source = op->s->mirror_top_bs->backing; 1432 1433 if (QLIST_FIRST(&source->bs->parents) == source && 1434 QLIST_NEXT(source, next_parent) == NULL) 1435 { 1436 /* Assert that we are back in sync once all active write 1437 * operations are settled. 1438 * Note that we can only assert this if the mirror node 1439 * is the source node's only parent. */ 1440 assert(!bdrv_get_dirty_count(op->s->dirty_bitmap)); 1441 } 1442 } 1443 bitmap_clear(op->s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1444 QTAILQ_REMOVE(&op->s->ops_in_flight, op, next); 1445 qemu_co_queue_restart_all(&op->waiting_requests); 1446 g_free(op); 1447 } 1448 1449 static int coroutine_fn GRAPH_RDLOCK 1450 bdrv_mirror_top_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes, 1451 QEMUIOVector *qiov, BdrvRequestFlags flags) 1452 { 1453 return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); 1454 } 1455 1456 static int coroutine_fn GRAPH_RDLOCK 1457 bdrv_mirror_top_do_write(BlockDriverState *bs, MirrorMethod method, 1458 uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, 1459 int flags) 1460 { 1461 MirrorOp *op = NULL; 1462 MirrorBDSOpaque *s = bs->opaque; 1463 int ret = 0; 1464 bool copy_to_target = false; 1465 1466 if (s->job) { 1467 copy_to_target = s->job->ret >= 0 && 1468 !job_is_cancelled(&s->job->common.job) && 1469 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING; 1470 } 1471 1472 if (copy_to_target) { 1473 op = active_write_prepare(s->job, offset, bytes); 1474 } 1475 1476 switch (method) { 1477 case MIRROR_METHOD_COPY: 1478 ret = bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags); 1479 break; 1480 1481 case MIRROR_METHOD_ZERO: 1482 ret = bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags); 1483 break; 1484 1485 case MIRROR_METHOD_DISCARD: 1486 ret = bdrv_co_pdiscard(bs->backing, offset, bytes); 1487 break; 1488 1489 default: 1490 abort(); 1491 } 1492 1493 if (ret < 0) { 1494 goto out; 1495 } 1496 1497 if (copy_to_target) { 1498 do_sync_target_write(s->job, method, offset, bytes, qiov, flags); 1499 } 1500 1501 out: 1502 if (copy_to_target) { 1503 active_write_settle(op); 1504 } 1505 return ret; 1506 } 1507 1508 static int coroutine_fn GRAPH_RDLOCK 1509 bdrv_mirror_top_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes, 1510 QEMUIOVector *qiov, BdrvRequestFlags flags) 1511 { 1512 MirrorBDSOpaque *s = bs->opaque; 1513 QEMUIOVector bounce_qiov; 1514 void *bounce_buf; 1515 int ret = 0; 1516 bool copy_to_target = false; 1517 1518 if (s->job) { 1519 copy_to_target = s->job->ret >= 0 && 1520 !job_is_cancelled(&s->job->common.job) && 1521 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING; 1522 } 1523 1524 if (copy_to_target) { 1525 /* The guest might concurrently modify the data to write; but 1526 * the data on source and destination must match, so we have 1527 * to use a bounce buffer if we are going to write to the 1528 * target now. */ 1529 bounce_buf = qemu_blockalign(bs, bytes); 1530 iov_to_buf_full(qiov->iov, qiov->niov, 0, bounce_buf, bytes); 1531 1532 qemu_iovec_init(&bounce_qiov, 1); 1533 qemu_iovec_add(&bounce_qiov, bounce_buf, bytes); 1534 qiov = &bounce_qiov; 1535 1536 flags &= ~BDRV_REQ_REGISTERED_BUF; 1537 } 1538 1539 ret = bdrv_mirror_top_do_write(bs, MIRROR_METHOD_COPY, offset, bytes, qiov, 1540 flags); 1541 1542 if (copy_to_target) { 1543 qemu_iovec_destroy(&bounce_qiov); 1544 qemu_vfree(bounce_buf); 1545 } 1546 1547 return ret; 1548 } 1549 1550 static int coroutine_fn GRAPH_RDLOCK bdrv_mirror_top_flush(BlockDriverState *bs) 1551 { 1552 if (bs->backing == NULL) { 1553 /* we can be here after failed bdrv_append in mirror_start_job */ 1554 return 0; 1555 } 1556 return bdrv_co_flush(bs->backing->bs); 1557 } 1558 1559 static int coroutine_fn GRAPH_RDLOCK 1560 bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs, int64_t offset, 1561 int64_t bytes, BdrvRequestFlags flags) 1562 { 1563 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_ZERO, offset, bytes, NULL, 1564 flags); 1565 } 1566 1567 static int coroutine_fn GRAPH_RDLOCK 1568 bdrv_mirror_top_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes) 1569 { 1570 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_DISCARD, offset, bytes, 1571 NULL, 0); 1572 } 1573 1574 static void bdrv_mirror_top_refresh_filename(BlockDriverState *bs) 1575 { 1576 if (bs->backing == NULL) { 1577 /* we can be here after failed bdrv_attach_child in 1578 * bdrv_set_backing_hd */ 1579 return; 1580 } 1581 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), 1582 bs->backing->bs->filename); 1583 } 1584 1585 static void bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c, 1586 BdrvChildRole role, 1587 BlockReopenQueue *reopen_queue, 1588 uint64_t perm, uint64_t shared, 1589 uint64_t *nperm, uint64_t *nshared) 1590 { 1591 MirrorBDSOpaque *s = bs->opaque; 1592 1593 if (s->stop) { 1594 /* 1595 * If the job is to be stopped, we do not need to forward 1596 * anything to the real image. 1597 */ 1598 *nperm = 0; 1599 *nshared = BLK_PERM_ALL; 1600 return; 1601 } 1602 1603 bdrv_default_perms(bs, c, role, reopen_queue, 1604 perm, shared, nperm, nshared); 1605 1606 if (s->is_commit) { 1607 /* 1608 * For commit jobs, we cannot take CONSISTENT_READ, because 1609 * that permission is unshared for everything above the base 1610 * node (except for filters on the base node). 1611 * We also have to force-share the WRITE permission, or 1612 * otherwise we would block ourselves at the base node (if 1613 * writes are blocked for a node, they are also blocked for 1614 * its backing file). 1615 * (We could also share RESIZE, because it may be needed for 1616 * the target if its size is less than the top node's; but 1617 * bdrv_default_perms_for_cow() automatically shares RESIZE 1618 * for backing nodes if WRITE is shared, so there is no need 1619 * to do it here.) 1620 */ 1621 *nperm &= ~BLK_PERM_CONSISTENT_READ; 1622 *nshared |= BLK_PERM_WRITE; 1623 } 1624 } 1625 1626 /* Dummy node that provides consistent read to its users without requiring it 1627 * from its backing file and that allows writes on the backing file chain. */ 1628 static BlockDriver bdrv_mirror_top = { 1629 .format_name = "mirror_top", 1630 .bdrv_co_preadv = bdrv_mirror_top_preadv, 1631 .bdrv_co_pwritev = bdrv_mirror_top_pwritev, 1632 .bdrv_co_pwrite_zeroes = bdrv_mirror_top_pwrite_zeroes, 1633 .bdrv_co_pdiscard = bdrv_mirror_top_pdiscard, 1634 .bdrv_co_flush = bdrv_mirror_top_flush, 1635 .bdrv_refresh_filename = bdrv_mirror_top_refresh_filename, 1636 .bdrv_child_perm = bdrv_mirror_top_child_perm, 1637 1638 .is_filter = true, 1639 .filtered_child_is_backing = true, 1640 }; 1641 1642 static BlockJob *mirror_start_job( 1643 const char *job_id, BlockDriverState *bs, 1644 int creation_flags, BlockDriverState *target, 1645 const char *replaces, int64_t speed, 1646 uint32_t granularity, int64_t buf_size, 1647 BlockMirrorBackingMode backing_mode, 1648 bool zero_target, 1649 BlockdevOnError on_source_error, 1650 BlockdevOnError on_target_error, 1651 bool unmap, 1652 BlockCompletionFunc *cb, 1653 void *opaque, 1654 const BlockJobDriver *driver, 1655 bool is_none_mode, BlockDriverState *base, 1656 bool auto_complete, const char *filter_node_name, 1657 bool is_mirror, MirrorCopyMode copy_mode, 1658 Error **errp) 1659 { 1660 MirrorBlockJob *s; 1661 MirrorBDSOpaque *bs_opaque; 1662 BlockDriverState *mirror_top_bs; 1663 bool target_is_backing; 1664 uint64_t target_perms, target_shared_perms; 1665 int ret; 1666 1667 if (granularity == 0) { 1668 granularity = bdrv_get_default_bitmap_granularity(target); 1669 } 1670 1671 assert(is_power_of_2(granularity)); 1672 1673 if (buf_size < 0) { 1674 error_setg(errp, "Invalid parameter 'buf-size'"); 1675 return NULL; 1676 } 1677 1678 if (buf_size == 0) { 1679 buf_size = DEFAULT_MIRROR_BUF_SIZE; 1680 } 1681 1682 if (bdrv_skip_filters(bs) == bdrv_skip_filters(target)) { 1683 error_setg(errp, "Can't mirror node into itself"); 1684 return NULL; 1685 } 1686 1687 target_is_backing = bdrv_chain_contains(bs, target); 1688 1689 /* In the case of active commit, add dummy driver to provide consistent 1690 * reads on the top, while disabling it in the intermediate nodes, and make 1691 * the backing chain writable. */ 1692 mirror_top_bs = bdrv_new_open_driver(&bdrv_mirror_top, filter_node_name, 1693 BDRV_O_RDWR, errp); 1694 if (mirror_top_bs == NULL) { 1695 return NULL; 1696 } 1697 if (!filter_node_name) { 1698 mirror_top_bs->implicit = true; 1699 } 1700 1701 /* So that we can always drop this node */ 1702 mirror_top_bs->never_freeze = true; 1703 1704 mirror_top_bs->total_sectors = bs->total_sectors; 1705 mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED; 1706 mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED | 1707 BDRV_REQ_NO_FALLBACK; 1708 bs_opaque = g_new0(MirrorBDSOpaque, 1); 1709 mirror_top_bs->opaque = bs_opaque; 1710 1711 bs_opaque->is_commit = target_is_backing; 1712 1713 bdrv_drained_begin(bs); 1714 ret = bdrv_append(mirror_top_bs, bs, errp); 1715 bdrv_drained_end(bs); 1716 1717 if (ret < 0) { 1718 bdrv_unref(mirror_top_bs); 1719 return NULL; 1720 } 1721 1722 /* Make sure that the source is not resized while the job is running */ 1723 s = block_job_create(job_id, driver, NULL, mirror_top_bs, 1724 BLK_PERM_CONSISTENT_READ, 1725 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | 1726 BLK_PERM_WRITE, speed, 1727 creation_flags, cb, opaque, errp); 1728 if (!s) { 1729 goto fail; 1730 } 1731 1732 /* The block job now has a reference to this node */ 1733 bdrv_unref(mirror_top_bs); 1734 1735 s->mirror_top_bs = mirror_top_bs; 1736 1737 /* No resize for the target either; while the mirror is still running, a 1738 * consistent read isn't necessarily possible. We could possibly allow 1739 * writes and graph modifications, though it would likely defeat the 1740 * purpose of a mirror, so leave them blocked for now. 1741 * 1742 * In the case of active commit, things look a bit different, though, 1743 * because the target is an already populated backing file in active use. 1744 * We can allow anything except resize there.*/ 1745 1746 target_perms = BLK_PERM_WRITE; 1747 target_shared_perms = BLK_PERM_WRITE_UNCHANGED; 1748 1749 if (target_is_backing) { 1750 int64_t bs_size, target_size; 1751 bs_size = bdrv_getlength(bs); 1752 if (bs_size < 0) { 1753 error_setg_errno(errp, -bs_size, 1754 "Could not inquire top image size"); 1755 goto fail; 1756 } 1757 1758 target_size = bdrv_getlength(target); 1759 if (target_size < 0) { 1760 error_setg_errno(errp, -target_size, 1761 "Could not inquire base image size"); 1762 goto fail; 1763 } 1764 1765 if (target_size < bs_size) { 1766 target_perms |= BLK_PERM_RESIZE; 1767 } 1768 1769 target_shared_perms |= BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE; 1770 } else if (bdrv_chain_contains(bs, bdrv_skip_filters(target))) { 1771 /* 1772 * We may want to allow this in the future, but it would 1773 * require taking some extra care. 1774 */ 1775 error_setg(errp, "Cannot mirror to a filter on top of a node in the " 1776 "source's backing chain"); 1777 goto fail; 1778 } 1779 1780 s->target = blk_new(s->common.job.aio_context, 1781 target_perms, target_shared_perms); 1782 ret = blk_insert_bs(s->target, target, errp); 1783 if (ret < 0) { 1784 goto fail; 1785 } 1786 if (is_mirror) { 1787 /* XXX: Mirror target could be a NBD server of target QEMU in the case 1788 * of non-shared block migration. To allow migration completion, we 1789 * have to allow "inactivate" of the target BB. When that happens, we 1790 * know the job is drained, and the vcpus are stopped, so no write 1791 * operation will be performed. Block layer already has assertions to 1792 * ensure that. */ 1793 blk_set_force_allow_inactivate(s->target); 1794 } 1795 blk_set_allow_aio_context_change(s->target, true); 1796 blk_set_disable_request_queuing(s->target, true); 1797 1798 s->replaces = g_strdup(replaces); 1799 s->on_source_error = on_source_error; 1800 s->on_target_error = on_target_error; 1801 s->is_none_mode = is_none_mode; 1802 s->backing_mode = backing_mode; 1803 s->zero_target = zero_target; 1804 s->copy_mode = copy_mode; 1805 s->base = base; 1806 s->base_overlay = bdrv_find_overlay(bs, base); 1807 s->granularity = granularity; 1808 s->buf_size = ROUND_UP(buf_size, granularity); 1809 s->unmap = unmap; 1810 if (auto_complete) { 1811 s->should_complete = true; 1812 } 1813 1814 s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp); 1815 if (!s->dirty_bitmap) { 1816 goto fail; 1817 } 1818 if (s->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING) { 1819 bdrv_disable_dirty_bitmap(s->dirty_bitmap); 1820 } 1821 1822 ret = block_job_add_bdrv(&s->common, "source", bs, 0, 1823 BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE | 1824 BLK_PERM_CONSISTENT_READ, 1825 errp); 1826 if (ret < 0) { 1827 goto fail; 1828 } 1829 1830 /* Required permissions are already taken with blk_new() */ 1831 block_job_add_bdrv(&s->common, "target", target, 0, BLK_PERM_ALL, 1832 &error_abort); 1833 1834 /* In commit_active_start() all intermediate nodes disappear, so 1835 * any jobs in them must be blocked */ 1836 if (target_is_backing) { 1837 BlockDriverState *iter, *filtered_target; 1838 uint64_t iter_shared_perms; 1839 1840 /* 1841 * The topmost node with 1842 * bdrv_skip_filters(filtered_target) == bdrv_skip_filters(target) 1843 */ 1844 filtered_target = bdrv_cow_bs(bdrv_find_overlay(bs, target)); 1845 1846 assert(bdrv_skip_filters(filtered_target) == 1847 bdrv_skip_filters(target)); 1848 1849 /* 1850 * XXX BLK_PERM_WRITE needs to be allowed so we don't block 1851 * ourselves at s->base (if writes are blocked for a node, they are 1852 * also blocked for its backing file). The other options would be a 1853 * second filter driver above s->base (== target). 1854 */ 1855 iter_shared_perms = BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE; 1856 1857 for (iter = bdrv_filter_or_cow_bs(bs); iter != target; 1858 iter = bdrv_filter_or_cow_bs(iter)) 1859 { 1860 if (iter == filtered_target) { 1861 /* 1862 * From here on, all nodes are filters on the base. 1863 * This allows us to share BLK_PERM_CONSISTENT_READ. 1864 */ 1865 iter_shared_perms |= BLK_PERM_CONSISTENT_READ; 1866 } 1867 1868 ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, 1869 iter_shared_perms, errp); 1870 if (ret < 0) { 1871 goto fail; 1872 } 1873 } 1874 1875 if (bdrv_freeze_backing_chain(mirror_top_bs, target, errp) < 0) { 1876 goto fail; 1877 } 1878 } 1879 1880 QTAILQ_INIT(&s->ops_in_flight); 1881 1882 trace_mirror_start(bs, s, opaque); 1883 job_start(&s->common.job); 1884 1885 return &s->common; 1886 1887 fail: 1888 if (s) { 1889 /* Make sure this BDS does not go away until we have completed the graph 1890 * changes below */ 1891 bdrv_ref(mirror_top_bs); 1892 1893 g_free(s->replaces); 1894 blk_unref(s->target); 1895 bs_opaque->job = NULL; 1896 if (s->dirty_bitmap) { 1897 bdrv_release_dirty_bitmap(s->dirty_bitmap); 1898 } 1899 job_early_fail(&s->common.job); 1900 } 1901 1902 bs_opaque->stop = true; 1903 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 1904 &error_abort); 1905 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort); 1906 1907 bdrv_unref(mirror_top_bs); 1908 1909 return NULL; 1910 } 1911 1912 void mirror_start(const char *job_id, BlockDriverState *bs, 1913 BlockDriverState *target, const char *replaces, 1914 int creation_flags, int64_t speed, 1915 uint32_t granularity, int64_t buf_size, 1916 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, 1917 bool zero_target, 1918 BlockdevOnError on_source_error, 1919 BlockdevOnError on_target_error, 1920 bool unmap, const char *filter_node_name, 1921 MirrorCopyMode copy_mode, Error **errp) 1922 { 1923 bool is_none_mode; 1924 BlockDriverState *base; 1925 1926 GLOBAL_STATE_CODE(); 1927 1928 if ((mode == MIRROR_SYNC_MODE_INCREMENTAL) || 1929 (mode == MIRROR_SYNC_MODE_BITMAP)) { 1930 error_setg(errp, "Sync mode '%s' not supported", 1931 MirrorSyncMode_str(mode)); 1932 return; 1933 } 1934 is_none_mode = mode == MIRROR_SYNC_MODE_NONE; 1935 base = mode == MIRROR_SYNC_MODE_TOP ? bdrv_backing_chain_next(bs) : NULL; 1936 mirror_start_job(job_id, bs, creation_flags, target, replaces, 1937 speed, granularity, buf_size, backing_mode, zero_target, 1938 on_source_error, on_target_error, unmap, NULL, NULL, 1939 &mirror_job_driver, is_none_mode, base, false, 1940 filter_node_name, true, copy_mode, errp); 1941 } 1942 1943 BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs, 1944 BlockDriverState *base, int creation_flags, 1945 int64_t speed, BlockdevOnError on_error, 1946 const char *filter_node_name, 1947 BlockCompletionFunc *cb, void *opaque, 1948 bool auto_complete, Error **errp) 1949 { 1950 bool base_read_only; 1951 BlockJob *job; 1952 1953 GLOBAL_STATE_CODE(); 1954 1955 base_read_only = bdrv_is_read_only(base); 1956 1957 if (base_read_only) { 1958 if (bdrv_reopen_set_read_only(base, false, errp) < 0) { 1959 return NULL; 1960 } 1961 } 1962 1963 job = mirror_start_job( 1964 job_id, bs, creation_flags, base, NULL, speed, 0, 0, 1965 MIRROR_LEAVE_BACKING_CHAIN, false, 1966 on_error, on_error, true, cb, opaque, 1967 &commit_active_job_driver, false, base, auto_complete, 1968 filter_node_name, false, MIRROR_COPY_MODE_BACKGROUND, 1969 errp); 1970 if (!job) { 1971 goto error_restore_flags; 1972 } 1973 1974 return job; 1975 1976 error_restore_flags: 1977 /* ignore error and errp for bdrv_reopen, because we want to propagate 1978 * the original error */ 1979 if (base_read_only) { 1980 bdrv_reopen_set_read_only(base, true, NULL); 1981 } 1982 return NULL; 1983 } 1984