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 /* 59 * To be accesssed with atomics. Written only under the BQL (required by the 60 * current implementation of mirror_change()). 61 */ 62 MirrorCopyMode copy_mode; 63 BlockdevOnError on_source_error, on_target_error; 64 /* 65 * To be accessed with atomics. 66 * 67 * Set when the target is synced (dirty bitmap is clean, nothing in flight) 68 * and the job is running in active mode. 69 */ 70 bool actively_synced; 71 bool should_complete; 72 int64_t granularity; 73 size_t buf_size; 74 int64_t bdev_length; 75 unsigned long *cow_bitmap; 76 BdrvDirtyBitmap *dirty_bitmap; 77 BdrvDirtyBitmapIter *dbi; 78 uint8_t *buf; 79 QSIMPLEQ_HEAD(, MirrorBuffer) buf_free; 80 int buf_free_count; 81 82 uint64_t last_pause_ns; 83 unsigned long *in_flight_bitmap; 84 unsigned in_flight; 85 int64_t bytes_in_flight; 86 QTAILQ_HEAD(, MirrorOp) ops_in_flight; 87 int ret; 88 bool unmap; 89 int target_cluster_size; 90 int max_iov; 91 bool initial_zeroing_ongoing; 92 int in_active_write_counter; 93 int64_t active_write_bytes_in_flight; 94 bool prepared; 95 bool in_drain; 96 } MirrorBlockJob; 97 98 typedef struct MirrorBDSOpaque { 99 MirrorBlockJob *job; 100 bool stop; 101 bool is_commit; 102 } MirrorBDSOpaque; 103 104 struct MirrorOp { 105 MirrorBlockJob *s; 106 QEMUIOVector qiov; 107 int64_t offset; 108 uint64_t bytes; 109 110 /* The pointee is set by mirror_co_read(), mirror_co_zero(), and 111 * mirror_co_discard() before yielding for the first time */ 112 int64_t *bytes_handled; 113 114 bool is_pseudo_op; 115 bool is_active_write; 116 bool is_in_flight; 117 CoQueue waiting_requests; 118 Coroutine *co; 119 MirrorOp *waiting_for_op; 120 121 QTAILQ_ENTRY(MirrorOp) next; 122 }; 123 124 typedef enum MirrorMethod { 125 MIRROR_METHOD_COPY, 126 MIRROR_METHOD_ZERO, 127 MIRROR_METHOD_DISCARD, 128 } MirrorMethod; 129 130 static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, 131 int error) 132 { 133 qatomic_set(&s->actively_synced, false); 134 if (read) { 135 return block_job_error_action(&s->common, s->on_source_error, 136 true, error); 137 } else { 138 return block_job_error_action(&s->common, s->on_target_error, 139 false, error); 140 } 141 } 142 143 static void coroutine_fn mirror_wait_on_conflicts(MirrorOp *self, 144 MirrorBlockJob *s, 145 uint64_t offset, 146 uint64_t bytes) 147 { 148 uint64_t self_start_chunk = offset / s->granularity; 149 uint64_t self_end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 150 uint64_t self_nb_chunks = self_end_chunk - self_start_chunk; 151 152 while (find_next_bit(s->in_flight_bitmap, self_end_chunk, 153 self_start_chunk) < self_end_chunk && 154 s->ret >= 0) 155 { 156 MirrorOp *op; 157 158 QTAILQ_FOREACH(op, &s->ops_in_flight, next) { 159 uint64_t op_start_chunk = op->offset / s->granularity; 160 uint64_t op_nb_chunks = DIV_ROUND_UP(op->offset + op->bytes, 161 s->granularity) - 162 op_start_chunk; 163 164 if (op == self) { 165 continue; 166 } 167 168 if (ranges_overlap(self_start_chunk, self_nb_chunks, 169 op_start_chunk, op_nb_chunks)) 170 { 171 if (self) { 172 /* 173 * If the operation is already (indirectly) waiting for us, 174 * or will wait for us as soon as it wakes up, then just go 175 * on (instead of producing a deadlock in the former case). 176 */ 177 if (op->waiting_for_op) { 178 continue; 179 } 180 181 self->waiting_for_op = op; 182 } 183 184 qemu_co_queue_wait(&op->waiting_requests, NULL); 185 186 if (self) { 187 self->waiting_for_op = NULL; 188 } 189 190 break; 191 } 192 } 193 } 194 } 195 196 static void coroutine_fn mirror_iteration_done(MirrorOp *op, int ret) 197 { 198 MirrorBlockJob *s = op->s; 199 struct iovec *iov; 200 int64_t chunk_num; 201 int i, nb_chunks; 202 203 trace_mirror_iteration_done(s, op->offset, op->bytes, ret); 204 205 s->in_flight--; 206 s->bytes_in_flight -= op->bytes; 207 iov = op->qiov.iov; 208 for (i = 0; i < op->qiov.niov; i++) { 209 MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base; 210 QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next); 211 s->buf_free_count++; 212 } 213 214 chunk_num = op->offset / s->granularity; 215 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity); 216 217 bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks); 218 QTAILQ_REMOVE(&s->ops_in_flight, op, next); 219 if (ret >= 0) { 220 if (s->cow_bitmap) { 221 bitmap_set(s->cow_bitmap, chunk_num, nb_chunks); 222 } 223 if (!s->initial_zeroing_ongoing) { 224 job_progress_update(&s->common.job, op->bytes); 225 } 226 } 227 qemu_iovec_destroy(&op->qiov); 228 229 qemu_co_queue_restart_all(&op->waiting_requests); 230 g_free(op); 231 } 232 233 static void coroutine_fn mirror_write_complete(MirrorOp *op, int ret) 234 { 235 MirrorBlockJob *s = op->s; 236 237 if (ret < 0) { 238 BlockErrorAction action; 239 240 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes); 241 action = mirror_error_action(s, false, -ret); 242 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 243 s->ret = ret; 244 } 245 } 246 247 mirror_iteration_done(op, ret); 248 } 249 250 static void coroutine_fn mirror_read_complete(MirrorOp *op, int ret) 251 { 252 MirrorBlockJob *s = op->s; 253 254 if (ret < 0) { 255 BlockErrorAction action; 256 257 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes); 258 action = mirror_error_action(s, true, -ret); 259 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 260 s->ret = ret; 261 } 262 263 mirror_iteration_done(op, ret); 264 return; 265 } 266 267 ret = blk_co_pwritev(s->target, op->offset, op->qiov.size, &op->qiov, 0); 268 mirror_write_complete(op, ret); 269 } 270 271 /* Clip bytes relative to offset to not exceed end-of-file */ 272 static inline int64_t mirror_clip_bytes(MirrorBlockJob *s, 273 int64_t offset, 274 int64_t bytes) 275 { 276 return MIN(bytes, s->bdev_length - offset); 277 } 278 279 /* Round offset and/or bytes to target cluster if COW is needed, and 280 * return the offset of the adjusted tail against original. */ 281 static int coroutine_fn mirror_cow_align(MirrorBlockJob *s, int64_t *offset, 282 uint64_t *bytes) 283 { 284 bool need_cow; 285 int ret = 0; 286 int64_t align_offset = *offset; 287 int64_t align_bytes = *bytes; 288 int max_bytes = s->granularity * s->max_iov; 289 290 need_cow = !test_bit(*offset / s->granularity, s->cow_bitmap); 291 need_cow |= !test_bit((*offset + *bytes - 1) / s->granularity, 292 s->cow_bitmap); 293 if (need_cow) { 294 bdrv_round_to_subclusters(blk_bs(s->target), *offset, *bytes, 295 &align_offset, &align_bytes); 296 } 297 298 if (align_bytes > max_bytes) { 299 align_bytes = max_bytes; 300 if (need_cow) { 301 align_bytes = QEMU_ALIGN_DOWN(align_bytes, s->target_cluster_size); 302 } 303 } 304 /* Clipping may result in align_bytes unaligned to chunk boundary, but 305 * that doesn't matter because it's already the end of source image. */ 306 align_bytes = mirror_clip_bytes(s, align_offset, align_bytes); 307 308 ret = align_offset + align_bytes - (*offset + *bytes); 309 *offset = align_offset; 310 *bytes = align_bytes; 311 assert(ret >= 0); 312 return ret; 313 } 314 315 static inline void coroutine_fn 316 mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s) 317 { 318 MirrorOp *op; 319 320 QTAILQ_FOREACH(op, &s->ops_in_flight, next) { 321 /* 322 * Do not wait on pseudo ops, because it may in turn wait on 323 * some other operation to start, which may in fact be the 324 * caller of this function. Since there is only one pseudo op 325 * at any given time, we will always find some real operation 326 * to wait on. 327 * Also, do not wait on active operations, because they do not 328 * use up in-flight slots. 329 */ 330 if (!op->is_pseudo_op && op->is_in_flight && !op->is_active_write) { 331 qemu_co_queue_wait(&op->waiting_requests, NULL); 332 return; 333 } 334 } 335 abort(); 336 } 337 338 /* Perform a mirror copy operation. 339 * 340 * *op->bytes_handled is set to the number of bytes copied after and 341 * including offset, excluding any bytes copied prior to offset due 342 * to alignment. This will be op->bytes if no alignment is necessary, 343 * or (new_end - op->offset) if the tail is rounded up or down due to 344 * alignment or buffer limit. 345 */ 346 static void coroutine_fn mirror_co_read(void *opaque) 347 { 348 MirrorOp *op = opaque; 349 MirrorBlockJob *s = op->s; 350 int nb_chunks; 351 uint64_t ret; 352 uint64_t max_bytes; 353 354 max_bytes = s->granularity * s->max_iov; 355 356 /* We can only handle as much as buf_size at a time. */ 357 op->bytes = MIN(s->buf_size, MIN(max_bytes, op->bytes)); 358 assert(op->bytes); 359 assert(op->bytes < BDRV_REQUEST_MAX_BYTES); 360 *op->bytes_handled = op->bytes; 361 362 if (s->cow_bitmap) { 363 *op->bytes_handled += mirror_cow_align(s, &op->offset, &op->bytes); 364 } 365 /* Cannot exceed BDRV_REQUEST_MAX_BYTES + INT_MAX */ 366 assert(*op->bytes_handled <= UINT_MAX); 367 assert(op->bytes <= s->buf_size); 368 /* The offset is granularity-aligned because: 369 * 1) Caller passes in aligned values; 370 * 2) mirror_cow_align is used only when target cluster is larger. */ 371 assert(QEMU_IS_ALIGNED(op->offset, s->granularity)); 372 /* The range is sector-aligned, since bdrv_getlength() rounds up. */ 373 assert(QEMU_IS_ALIGNED(op->bytes, BDRV_SECTOR_SIZE)); 374 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity); 375 376 while (s->buf_free_count < nb_chunks) { 377 trace_mirror_yield_in_flight(s, op->offset, s->in_flight); 378 mirror_wait_for_free_in_flight_slot(s); 379 } 380 381 /* Now make a QEMUIOVector taking enough granularity-sized chunks 382 * from s->buf_free. 383 */ 384 qemu_iovec_init(&op->qiov, nb_chunks); 385 while (nb_chunks-- > 0) { 386 MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free); 387 size_t remaining = op->bytes - op->qiov.size; 388 389 QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next); 390 s->buf_free_count--; 391 qemu_iovec_add(&op->qiov, buf, MIN(s->granularity, remaining)); 392 } 393 394 /* Copy the dirty cluster. */ 395 s->in_flight++; 396 s->bytes_in_flight += op->bytes; 397 op->is_in_flight = true; 398 trace_mirror_one_iteration(s, op->offset, op->bytes); 399 400 WITH_GRAPH_RDLOCK_GUARD() { 401 ret = bdrv_co_preadv(s->mirror_top_bs->backing, op->offset, op->bytes, 402 &op->qiov, 0); 403 } 404 mirror_read_complete(op, ret); 405 } 406 407 static void coroutine_fn mirror_co_zero(void *opaque) 408 { 409 MirrorOp *op = opaque; 410 int ret; 411 412 op->s->in_flight++; 413 op->s->bytes_in_flight += op->bytes; 414 *op->bytes_handled = op->bytes; 415 op->is_in_flight = true; 416 417 ret = blk_co_pwrite_zeroes(op->s->target, op->offset, op->bytes, 418 op->s->unmap ? BDRV_REQ_MAY_UNMAP : 0); 419 mirror_write_complete(op, ret); 420 } 421 422 static void coroutine_fn mirror_co_discard(void *opaque) 423 { 424 MirrorOp *op = opaque; 425 int ret; 426 427 op->s->in_flight++; 428 op->s->bytes_in_flight += op->bytes; 429 *op->bytes_handled = op->bytes; 430 op->is_in_flight = true; 431 432 ret = blk_co_pdiscard(op->s->target, op->offset, op->bytes); 433 mirror_write_complete(op, ret); 434 } 435 436 static unsigned mirror_perform(MirrorBlockJob *s, int64_t offset, 437 unsigned bytes, MirrorMethod mirror_method) 438 { 439 MirrorOp *op; 440 Coroutine *co; 441 int64_t bytes_handled = -1; 442 443 op = g_new(MirrorOp, 1); 444 *op = (MirrorOp){ 445 .s = s, 446 .offset = offset, 447 .bytes = bytes, 448 .bytes_handled = &bytes_handled, 449 }; 450 qemu_co_queue_init(&op->waiting_requests); 451 452 switch (mirror_method) { 453 case MIRROR_METHOD_COPY: 454 co = qemu_coroutine_create(mirror_co_read, op); 455 break; 456 case MIRROR_METHOD_ZERO: 457 co = qemu_coroutine_create(mirror_co_zero, op); 458 break; 459 case MIRROR_METHOD_DISCARD: 460 co = qemu_coroutine_create(mirror_co_discard, op); 461 break; 462 default: 463 abort(); 464 } 465 op->co = co; 466 467 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 468 qemu_coroutine_enter(co); 469 /* At this point, ownership of op has been moved to the coroutine 470 * and the object may already be freed */ 471 472 /* Assert that this value has been set */ 473 assert(bytes_handled >= 0); 474 475 /* Same assertion as in mirror_co_read() (and for mirror_co_read() 476 * and mirror_co_discard(), bytes_handled == op->bytes, which 477 * is the @bytes parameter given to this function) */ 478 assert(bytes_handled <= UINT_MAX); 479 return bytes_handled; 480 } 481 482 static void coroutine_fn GRAPH_RDLOCK mirror_iteration(MirrorBlockJob *s) 483 { 484 BlockDriverState *source = s->mirror_top_bs->backing->bs; 485 MirrorOp *pseudo_op; 486 int64_t offset; 487 /* At least the first dirty chunk is mirrored in one iteration. */ 488 int nb_chunks = 1; 489 bool write_zeroes_ok = bdrv_can_write_zeroes_with_unmap(blk_bs(s->target)); 490 int max_io_bytes = MAX(s->buf_size / MAX_IN_FLIGHT, MAX_IO_BYTES); 491 492 bdrv_dirty_bitmap_lock(s->dirty_bitmap); 493 offset = bdrv_dirty_iter_next(s->dbi); 494 if (offset < 0) { 495 bdrv_set_dirty_iter(s->dbi, 0); 496 offset = bdrv_dirty_iter_next(s->dbi); 497 trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap)); 498 assert(offset >= 0); 499 } 500 bdrv_dirty_bitmap_unlock(s->dirty_bitmap); 501 502 /* 503 * Wait for concurrent requests to @offset. The next loop will limit the 504 * copied area based on in_flight_bitmap so we only copy an area that does 505 * not overlap with concurrent in-flight requests. Still, we would like to 506 * copy something, so wait until there are at least no more requests to the 507 * very beginning of the area. 508 */ 509 mirror_wait_on_conflicts(NULL, s, offset, 1); 510 511 job_pause_point(&s->common.job); 512 513 /* Find the number of consecutive dirty chunks following the first dirty 514 * one, and wait for in flight requests in them. */ 515 bdrv_dirty_bitmap_lock(s->dirty_bitmap); 516 while (nb_chunks * s->granularity < s->buf_size) { 517 int64_t next_dirty; 518 int64_t next_offset = offset + nb_chunks * s->granularity; 519 int64_t next_chunk = next_offset / s->granularity; 520 if (next_offset >= s->bdev_length || 521 !bdrv_dirty_bitmap_get_locked(s->dirty_bitmap, next_offset)) { 522 break; 523 } 524 if (test_bit(next_chunk, s->in_flight_bitmap)) { 525 break; 526 } 527 528 next_dirty = bdrv_dirty_iter_next(s->dbi); 529 if (next_dirty > next_offset || next_dirty < 0) { 530 /* The bitmap iterator's cache is stale, refresh it */ 531 bdrv_set_dirty_iter(s->dbi, next_offset); 532 next_dirty = bdrv_dirty_iter_next(s->dbi); 533 } 534 assert(next_dirty == next_offset); 535 nb_chunks++; 536 } 537 538 /* Clear dirty bits before querying the block status, because 539 * calling bdrv_block_status_above could yield - if some blocks are 540 * marked dirty in this window, we need to know. 541 */ 542 bdrv_reset_dirty_bitmap_locked(s->dirty_bitmap, offset, 543 nb_chunks * s->granularity); 544 bdrv_dirty_bitmap_unlock(s->dirty_bitmap); 545 546 /* Before claiming an area in the in-flight bitmap, we have to 547 * create a MirrorOp for it so that conflicting requests can wait 548 * for it. mirror_perform() will create the real MirrorOps later, 549 * for now we just create a pseudo operation that will wake up all 550 * conflicting requests once all real operations have been 551 * launched. */ 552 pseudo_op = g_new(MirrorOp, 1); 553 *pseudo_op = (MirrorOp){ 554 .offset = offset, 555 .bytes = nb_chunks * s->granularity, 556 .is_pseudo_op = true, 557 }; 558 qemu_co_queue_init(&pseudo_op->waiting_requests); 559 QTAILQ_INSERT_TAIL(&s->ops_in_flight, pseudo_op, next); 560 561 bitmap_set(s->in_flight_bitmap, offset / s->granularity, nb_chunks); 562 while (nb_chunks > 0 && offset < s->bdev_length) { 563 int ret; 564 int64_t io_bytes; 565 int64_t io_bytes_acct; 566 MirrorMethod mirror_method = MIRROR_METHOD_COPY; 567 568 assert(!(offset % s->granularity)); 569 WITH_GRAPH_RDLOCK_GUARD() { 570 ret = bdrv_co_block_status_above(source, NULL, offset, 571 nb_chunks * s->granularity, 572 &io_bytes, NULL, NULL); 573 } 574 if (ret < 0) { 575 io_bytes = MIN(nb_chunks * s->granularity, max_io_bytes); 576 } else if (ret & BDRV_BLOCK_DATA) { 577 io_bytes = MIN(io_bytes, max_io_bytes); 578 } 579 580 io_bytes -= io_bytes % s->granularity; 581 if (io_bytes < s->granularity) { 582 io_bytes = s->granularity; 583 } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) { 584 int64_t target_offset; 585 int64_t target_bytes; 586 WITH_GRAPH_RDLOCK_GUARD() { 587 bdrv_round_to_subclusters(blk_bs(s->target), offset, io_bytes, 588 &target_offset, &target_bytes); 589 } 590 if (target_offset == offset && 591 target_bytes == io_bytes) { 592 mirror_method = ret & BDRV_BLOCK_ZERO ? 593 MIRROR_METHOD_ZERO : 594 MIRROR_METHOD_DISCARD; 595 } 596 } 597 598 while (s->in_flight >= MAX_IN_FLIGHT) { 599 trace_mirror_yield_in_flight(s, offset, s->in_flight); 600 mirror_wait_for_free_in_flight_slot(s); 601 } 602 603 if (s->ret < 0) { 604 ret = 0; 605 goto fail; 606 } 607 608 io_bytes = mirror_clip_bytes(s, offset, io_bytes); 609 io_bytes = mirror_perform(s, offset, io_bytes, mirror_method); 610 if (mirror_method != MIRROR_METHOD_COPY && write_zeroes_ok) { 611 io_bytes_acct = 0; 612 } else { 613 io_bytes_acct = io_bytes; 614 } 615 assert(io_bytes); 616 offset += io_bytes; 617 nb_chunks -= DIV_ROUND_UP(io_bytes, s->granularity); 618 block_job_ratelimit_processed_bytes(&s->common, io_bytes_acct); 619 } 620 621 fail: 622 QTAILQ_REMOVE(&s->ops_in_flight, pseudo_op, next); 623 qemu_co_queue_restart_all(&pseudo_op->waiting_requests); 624 g_free(pseudo_op); 625 } 626 627 static void mirror_free_init(MirrorBlockJob *s) 628 { 629 int granularity = s->granularity; 630 size_t buf_size = s->buf_size; 631 uint8_t *buf = s->buf; 632 633 assert(s->buf_free_count == 0); 634 QSIMPLEQ_INIT(&s->buf_free); 635 while (buf_size != 0) { 636 MirrorBuffer *cur = (MirrorBuffer *)buf; 637 QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); 638 s->buf_free_count++; 639 buf_size -= granularity; 640 buf += granularity; 641 } 642 } 643 644 /* This is also used for the .pause callback. There is no matching 645 * mirror_resume() because mirror_run() will begin iterating again 646 * when the job is resumed. 647 */ 648 static void coroutine_fn mirror_wait_for_all_io(MirrorBlockJob *s) 649 { 650 while (s->in_flight > 0) { 651 mirror_wait_for_free_in_flight_slot(s); 652 } 653 } 654 655 /** 656 * mirror_exit_common: handle both abort() and prepare() cases. 657 * for .prepare, returns 0 on success and -errno on failure. 658 * for .abort cases, denoted by abort = true, MUST return 0. 659 */ 660 static int mirror_exit_common(Job *job) 661 { 662 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 663 BlockJob *bjob = &s->common; 664 MirrorBDSOpaque *bs_opaque; 665 BlockDriverState *src; 666 BlockDriverState *target_bs; 667 BlockDriverState *mirror_top_bs; 668 Error *local_err = NULL; 669 bool abort = job->ret < 0; 670 int ret = 0; 671 672 GLOBAL_STATE_CODE(); 673 674 if (s->prepared) { 675 return 0; 676 } 677 s->prepared = true; 678 679 bdrv_graph_rdlock_main_loop(); 680 681 mirror_top_bs = s->mirror_top_bs; 682 bs_opaque = mirror_top_bs->opaque; 683 src = mirror_top_bs->backing->bs; 684 target_bs = blk_bs(s->target); 685 686 if (bdrv_chain_contains(src, target_bs)) { 687 bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs); 688 } 689 690 bdrv_release_dirty_bitmap(s->dirty_bitmap); 691 692 /* Make sure that the source BDS doesn't go away during bdrv_replace_node, 693 * before we can call bdrv_drained_end */ 694 bdrv_ref(src); 695 bdrv_ref(mirror_top_bs); 696 bdrv_ref(target_bs); 697 698 bdrv_graph_rdunlock_main_loop(); 699 700 /* 701 * Remove target parent that still uses BLK_PERM_WRITE/RESIZE before 702 * inserting target_bs at s->to_replace, where we might not be able to get 703 * these permissions. 704 */ 705 blk_unref(s->target); 706 s->target = NULL; 707 708 /* We don't access the source any more. Dropping any WRITE/RESIZE is 709 * required before it could become a backing file of target_bs. Not having 710 * these permissions any more means that we can't allow any new requests on 711 * mirror_top_bs from now on, so keep it drained. */ 712 bdrv_drained_begin(mirror_top_bs); 713 bdrv_drained_begin(target_bs); 714 bs_opaque->stop = true; 715 716 bdrv_graph_rdlock_main_loop(); 717 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 718 &error_abort); 719 720 if (!abort && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { 721 BlockDriverState *backing = s->is_none_mode ? src : s->base; 722 BlockDriverState *unfiltered_target = bdrv_skip_filters(target_bs); 723 724 if (bdrv_cow_bs(unfiltered_target) != backing) { 725 bdrv_set_backing_hd(unfiltered_target, backing, &local_err); 726 if (local_err) { 727 error_report_err(local_err); 728 local_err = NULL; 729 ret = -EPERM; 730 } 731 } 732 } else if (!abort && s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { 733 assert(!bdrv_backing_chain_next(target_bs)); 734 ret = bdrv_open_backing_file(bdrv_skip_filters(target_bs), NULL, 735 "backing", &local_err); 736 if (ret < 0) { 737 error_report_err(local_err); 738 local_err = NULL; 739 } 740 } 741 bdrv_graph_rdunlock_main_loop(); 742 743 if (s->should_complete && !abort) { 744 BlockDriverState *to_replace = s->to_replace ?: src; 745 bool ro = bdrv_is_read_only(to_replace); 746 747 if (ro != bdrv_is_read_only(target_bs)) { 748 bdrv_reopen_set_read_only(target_bs, ro, NULL); 749 } 750 751 /* The mirror job has no requests in flight any more, but we need to 752 * drain potential other users of the BDS before changing the graph. */ 753 assert(s->in_drain); 754 bdrv_drained_begin(to_replace); 755 /* 756 * Cannot use check_to_replace_node() here, because that would 757 * check for an op blocker on @to_replace, and we have our own 758 * there. 759 */ 760 bdrv_graph_wrlock(); 761 if (bdrv_recurse_can_replace(src, to_replace)) { 762 bdrv_replace_node(to_replace, target_bs, &local_err); 763 } else { 764 error_setg(&local_err, "Can no longer replace '%s' by '%s', " 765 "because it can no longer be guaranteed that doing so " 766 "would not lead to an abrupt change of visible data", 767 to_replace->node_name, target_bs->node_name); 768 } 769 bdrv_graph_wrunlock(); 770 bdrv_drained_end(to_replace); 771 if (local_err) { 772 error_report_err(local_err); 773 ret = -EPERM; 774 } 775 } 776 if (s->to_replace) { 777 bdrv_op_unblock_all(s->to_replace, s->replace_blocker); 778 error_free(s->replace_blocker); 779 bdrv_unref(s->to_replace); 780 } 781 g_free(s->replaces); 782 783 /* 784 * Remove the mirror filter driver from the graph. Before this, get rid of 785 * the blockers on the intermediate nodes so that the resulting state is 786 * valid. 787 */ 788 block_job_remove_all_bdrv(bjob); 789 bdrv_graph_wrlock(); 790 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort); 791 bdrv_graph_wrunlock(); 792 793 bdrv_drained_end(target_bs); 794 bdrv_unref(target_bs); 795 796 bs_opaque->job = NULL; 797 798 bdrv_drained_end(src); 799 bdrv_drained_end(mirror_top_bs); 800 s->in_drain = false; 801 bdrv_unref(mirror_top_bs); 802 bdrv_unref(src); 803 804 return ret; 805 } 806 807 static int mirror_prepare(Job *job) 808 { 809 return mirror_exit_common(job); 810 } 811 812 static void mirror_abort(Job *job) 813 { 814 int ret = mirror_exit_common(job); 815 assert(ret == 0); 816 } 817 818 static void coroutine_fn mirror_throttle(MirrorBlockJob *s) 819 { 820 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 821 822 if (now - s->last_pause_ns > BLOCK_JOB_SLICE_TIME) { 823 s->last_pause_ns = now; 824 job_sleep_ns(&s->common.job, 0); 825 } else { 826 job_pause_point(&s->common.job); 827 } 828 } 829 830 static int coroutine_fn GRAPH_UNLOCKED mirror_dirty_init(MirrorBlockJob *s) 831 { 832 int64_t offset; 833 BlockDriverState *bs; 834 BlockDriverState *target_bs = blk_bs(s->target); 835 int ret; 836 int64_t count; 837 838 bdrv_graph_co_rdlock(); 839 bs = s->mirror_top_bs->backing->bs; 840 bdrv_graph_co_rdunlock(); 841 842 if (s->zero_target) { 843 if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { 844 bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length); 845 return 0; 846 } 847 848 s->initial_zeroing_ongoing = true; 849 for (offset = 0; offset < s->bdev_length; ) { 850 int bytes = MIN(s->bdev_length - offset, 851 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 852 853 mirror_throttle(s); 854 855 if (job_is_cancelled(&s->common.job)) { 856 s->initial_zeroing_ongoing = false; 857 return 0; 858 } 859 860 if (s->in_flight >= MAX_IN_FLIGHT) { 861 trace_mirror_yield(s, UINT64_MAX, s->buf_free_count, 862 s->in_flight); 863 mirror_wait_for_free_in_flight_slot(s); 864 continue; 865 } 866 867 mirror_perform(s, offset, bytes, MIRROR_METHOD_ZERO); 868 offset += bytes; 869 } 870 871 mirror_wait_for_all_io(s); 872 s->initial_zeroing_ongoing = false; 873 } 874 875 /* First part, loop on the sectors and initialize the dirty bitmap. */ 876 for (offset = 0; offset < s->bdev_length; ) { 877 /* Just to make sure we are not exceeding int limit. */ 878 int bytes = MIN(s->bdev_length - offset, 879 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 880 881 mirror_throttle(s); 882 883 if (job_is_cancelled(&s->common.job)) { 884 return 0; 885 } 886 887 WITH_GRAPH_RDLOCK_GUARD() { 888 ret = bdrv_co_is_allocated_above(bs, s->base_overlay, true, offset, 889 bytes, &count); 890 } 891 if (ret < 0) { 892 return ret; 893 } 894 895 assert(count); 896 if (ret > 0) { 897 bdrv_set_dirty_bitmap(s->dirty_bitmap, offset, count); 898 } 899 offset += count; 900 } 901 return 0; 902 } 903 904 /* Called when going out of the streaming phase to flush the bulk of the 905 * data to the medium, or just before completing. 906 */ 907 static int coroutine_fn mirror_flush(MirrorBlockJob *s) 908 { 909 int ret = blk_co_flush(s->target); 910 if (ret < 0) { 911 if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) { 912 s->ret = ret; 913 } 914 } 915 return ret; 916 } 917 918 static int coroutine_fn mirror_run(Job *job, Error **errp) 919 { 920 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 921 BlockDriverState *bs; 922 MirrorBDSOpaque *mirror_top_opaque = s->mirror_top_bs->opaque; 923 BlockDriverState *target_bs = blk_bs(s->target); 924 bool need_drain = true; 925 BlockDeviceIoStatus iostatus; 926 int64_t length; 927 int64_t target_length; 928 BlockDriverInfo bdi; 929 char backing_filename[2]; /* we only need 2 characters because we are only 930 checking for a NULL string */ 931 int ret = 0; 932 933 bdrv_graph_co_rdlock(); 934 bs = bdrv_filter_bs(s->mirror_top_bs); 935 bdrv_graph_co_rdunlock(); 936 937 if (job_is_cancelled(&s->common.job)) { 938 goto immediate_exit; 939 } 940 941 bdrv_graph_co_rdlock(); 942 s->bdev_length = bdrv_co_getlength(bs); 943 bdrv_graph_co_rdunlock(); 944 945 if (s->bdev_length < 0) { 946 ret = s->bdev_length; 947 goto immediate_exit; 948 } 949 950 target_length = blk_co_getlength(s->target); 951 if (target_length < 0) { 952 ret = target_length; 953 goto immediate_exit; 954 } 955 956 /* Active commit must resize the base image if its size differs from the 957 * active layer. */ 958 if (s->base == blk_bs(s->target)) { 959 if (s->bdev_length > target_length) { 960 ret = blk_co_truncate(s->target, s->bdev_length, false, 961 PREALLOC_MODE_OFF, 0, NULL); 962 if (ret < 0) { 963 goto immediate_exit; 964 } 965 } 966 } else if (s->bdev_length != target_length) { 967 error_setg(errp, "Source and target image have different sizes"); 968 ret = -EINVAL; 969 goto immediate_exit; 970 } 971 972 if (s->bdev_length == 0) { 973 /* Transition to the READY state and wait for complete. */ 974 job_transition_to_ready(&s->common.job); 975 qatomic_set(&s->actively_synced, true); 976 while (!job_cancel_requested(&s->common.job) && !s->should_complete) { 977 job_yield(&s->common.job); 978 } 979 goto immediate_exit; 980 } 981 982 length = DIV_ROUND_UP(s->bdev_length, s->granularity); 983 s->in_flight_bitmap = bitmap_new(length); 984 985 /* If we have no backing file yet in the destination, we cannot let 986 * the destination do COW. Instead, we copy sectors around the 987 * dirty data if needed. We need a bitmap to do that. 988 */ 989 bdrv_get_backing_filename(target_bs, backing_filename, 990 sizeof(backing_filename)); 991 bdrv_graph_co_rdlock(); 992 if (!bdrv_co_get_info(target_bs, &bdi) && bdi.cluster_size) { 993 s->target_cluster_size = bdi.cluster_size; 994 } else { 995 s->target_cluster_size = BDRV_SECTOR_SIZE; 996 } 997 if (backing_filename[0] && !bdrv_backing_chain_next(target_bs) && 998 s->granularity < s->target_cluster_size) { 999 s->buf_size = MAX(s->buf_size, s->target_cluster_size); 1000 s->cow_bitmap = bitmap_new(length); 1001 } 1002 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); 1003 bdrv_graph_co_rdunlock(); 1004 1005 s->buf = qemu_try_blockalign(bs, s->buf_size); 1006 if (s->buf == NULL) { 1007 ret = -ENOMEM; 1008 goto immediate_exit; 1009 } 1010 1011 mirror_free_init(s); 1012 1013 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 1014 if (!s->is_none_mode) { 1015 ret = mirror_dirty_init(s); 1016 if (ret < 0 || job_is_cancelled(&s->common.job)) { 1017 goto immediate_exit; 1018 } 1019 } 1020 1021 /* 1022 * Only now the job is fully initialised and mirror_top_bs should start 1023 * accessing it. 1024 */ 1025 mirror_top_opaque->job = s; 1026 1027 assert(!s->dbi); 1028 s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap); 1029 for (;;) { 1030 int64_t cnt, delta; 1031 bool should_complete; 1032 1033 if (s->ret < 0) { 1034 ret = s->ret; 1035 goto immediate_exit; 1036 } 1037 1038 job_pause_point(&s->common.job); 1039 1040 if (job_is_cancelled(&s->common.job)) { 1041 ret = 0; 1042 goto immediate_exit; 1043 } 1044 1045 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1046 /* cnt is the number of dirty bytes remaining and s->bytes_in_flight is 1047 * the number of bytes currently being processed; together those are 1048 * the current remaining operation length */ 1049 job_progress_set_remaining(&s->common.job, 1050 s->bytes_in_flight + cnt + 1051 s->active_write_bytes_in_flight); 1052 1053 /* Note that even when no rate limit is applied we need to yield 1054 * periodically with no pending I/O so that bdrv_drain_all() returns. 1055 * We do so every BLKOCK_JOB_SLICE_TIME nanoseconds, or when there is 1056 * an error, or when the source is clean, whichever comes first. */ 1057 delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns; 1058 WITH_JOB_LOCK_GUARD() { 1059 iostatus = s->common.iostatus; 1060 } 1061 if (delta < BLOCK_JOB_SLICE_TIME && 1062 iostatus == BLOCK_DEVICE_IO_STATUS_OK) { 1063 if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || 1064 (cnt == 0 && s->in_flight > 0)) { 1065 trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight); 1066 mirror_wait_for_free_in_flight_slot(s); 1067 continue; 1068 } else if (cnt != 0) { 1069 bdrv_graph_co_rdlock(); 1070 mirror_iteration(s); 1071 bdrv_graph_co_rdunlock(); 1072 } 1073 } 1074 1075 should_complete = false; 1076 if (s->in_flight == 0 && cnt == 0) { 1077 trace_mirror_before_flush(s); 1078 if (!job_is_ready(&s->common.job)) { 1079 if (mirror_flush(s) < 0) { 1080 /* Go check s->ret. */ 1081 continue; 1082 } 1083 /* We're out of the streaming phase. From now on, if the job 1084 * is cancelled we will actually complete all pending I/O and 1085 * report completion. This way, block-job-cancel will leave 1086 * the target in a consistent state. 1087 */ 1088 job_transition_to_ready(&s->common.job); 1089 } 1090 if (qatomic_read(&s->copy_mode) != MIRROR_COPY_MODE_BACKGROUND) { 1091 qatomic_set(&s->actively_synced, true); 1092 } 1093 1094 should_complete = s->should_complete || 1095 job_cancel_requested(&s->common.job); 1096 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1097 } 1098 1099 if (cnt == 0 && should_complete) { 1100 /* The dirty bitmap is not updated while operations are pending. 1101 * If we're about to exit, wait for pending operations before 1102 * calling bdrv_get_dirty_count(bs), or we may exit while the 1103 * source has dirty data to copy! 1104 * 1105 * Note that I/O can be submitted by the guest while 1106 * mirror_populate runs, so pause it now. Before deciding 1107 * whether to switch to target check one last time if I/O has 1108 * come in the meanwhile, and if not flush the data to disk. 1109 */ 1110 trace_mirror_before_drain(s, cnt); 1111 1112 s->in_drain = true; 1113 bdrv_drained_begin(bs); 1114 1115 /* Must be zero because we are drained */ 1116 assert(s->in_active_write_counter == 0); 1117 1118 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1119 if (cnt > 0 || mirror_flush(s) < 0) { 1120 bdrv_drained_end(bs); 1121 s->in_drain = false; 1122 continue; 1123 } 1124 1125 /* The two disks are in sync. Exit and report successful 1126 * completion. 1127 */ 1128 assert(QLIST_EMPTY(&bs->tracked_requests)); 1129 need_drain = false; 1130 break; 1131 } 1132 1133 if (job_is_ready(&s->common.job) && !should_complete) { 1134 if (s->in_flight == 0 && cnt == 0) { 1135 trace_mirror_before_sleep(s, cnt, job_is_ready(&s->common.job), 1136 BLOCK_JOB_SLICE_TIME); 1137 job_sleep_ns(&s->common.job, BLOCK_JOB_SLICE_TIME); 1138 } 1139 } else { 1140 block_job_ratelimit_sleep(&s->common); 1141 } 1142 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 1143 } 1144 1145 immediate_exit: 1146 if (s->in_flight > 0) { 1147 /* We get here only if something went wrong. Either the job failed, 1148 * or it was cancelled prematurely so that we do not guarantee that 1149 * the target is a copy of the source. 1150 */ 1151 assert(ret < 0 || job_is_cancelled(&s->common.job)); 1152 assert(need_drain); 1153 mirror_wait_for_all_io(s); 1154 } 1155 1156 assert(s->in_flight == 0); 1157 qemu_vfree(s->buf); 1158 g_free(s->cow_bitmap); 1159 g_free(s->in_flight_bitmap); 1160 bdrv_dirty_iter_free(s->dbi); 1161 1162 if (need_drain) { 1163 s->in_drain = true; 1164 bdrv_drained_begin(bs); 1165 } 1166 1167 return ret; 1168 } 1169 1170 static void mirror_complete(Job *job, Error **errp) 1171 { 1172 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1173 1174 if (!job_is_ready(job)) { 1175 error_setg(errp, "The active block job '%s' cannot be completed", 1176 job->id); 1177 return; 1178 } 1179 1180 /* block all operations on to_replace bs */ 1181 if (s->replaces) { 1182 s->to_replace = bdrv_find_node(s->replaces); 1183 if (!s->to_replace) { 1184 error_setg(errp, "Node name '%s' not found", s->replaces); 1185 return; 1186 } 1187 1188 /* TODO Translate this into child freeze system. */ 1189 error_setg(&s->replace_blocker, 1190 "block device is in use by block-job-complete"); 1191 bdrv_op_block_all(s->to_replace, s->replace_blocker); 1192 bdrv_ref(s->to_replace); 1193 } 1194 1195 s->should_complete = true; 1196 1197 /* If the job is paused, it will be re-entered when it is resumed */ 1198 WITH_JOB_LOCK_GUARD() { 1199 if (!job->paused) { 1200 job_enter_cond_locked(job, NULL); 1201 } 1202 } 1203 } 1204 1205 static void coroutine_fn mirror_pause(Job *job) 1206 { 1207 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1208 1209 mirror_wait_for_all_io(s); 1210 } 1211 1212 static bool mirror_drained_poll(BlockJob *job) 1213 { 1214 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1215 1216 /* If the job isn't paused nor cancelled, we can't be sure that it won't 1217 * issue more requests. We make an exception if we've reached this point 1218 * from one of our own drain sections, to avoid a deadlock waiting for 1219 * ourselves. 1220 */ 1221 WITH_JOB_LOCK_GUARD() { 1222 if (!s->common.job.paused && !job_is_cancelled_locked(&job->job) 1223 && !s->in_drain) { 1224 return true; 1225 } 1226 } 1227 1228 return !!s->in_flight; 1229 } 1230 1231 static bool mirror_cancel(Job *job, bool force) 1232 { 1233 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1234 BlockDriverState *target = blk_bs(s->target); 1235 1236 /* 1237 * Before the job is READY, we treat any cancellation like a 1238 * force-cancellation. 1239 */ 1240 force = force || !job_is_ready(job); 1241 1242 if (force) { 1243 bdrv_cancel_in_flight(target); 1244 } 1245 return force; 1246 } 1247 1248 static bool commit_active_cancel(Job *job, bool force) 1249 { 1250 /* Same as above in mirror_cancel() */ 1251 return force || !job_is_ready(job); 1252 } 1253 1254 static void mirror_change(BlockJob *job, BlockJobChangeOptions *opts, 1255 Error **errp) 1256 { 1257 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1258 BlockJobChangeOptionsMirror *change_opts = &opts->u.mirror; 1259 MirrorCopyMode current; 1260 1261 /* 1262 * The implementation relies on the fact that copy_mode is only written 1263 * under the BQL. Otherwise, further synchronization would be required. 1264 */ 1265 1266 GLOBAL_STATE_CODE(); 1267 1268 if (qatomic_read(&s->copy_mode) == change_opts->copy_mode) { 1269 return; 1270 } 1271 1272 if (change_opts->copy_mode != MIRROR_COPY_MODE_WRITE_BLOCKING) { 1273 error_setg(errp, "Change to copy mode '%s' is not implemented", 1274 MirrorCopyMode_str(change_opts->copy_mode)); 1275 return; 1276 } 1277 1278 current = qatomic_cmpxchg(&s->copy_mode, MIRROR_COPY_MODE_BACKGROUND, 1279 change_opts->copy_mode); 1280 if (current != MIRROR_COPY_MODE_BACKGROUND) { 1281 error_setg(errp, "Expected current copy mode '%s', got '%s'", 1282 MirrorCopyMode_str(MIRROR_COPY_MODE_BACKGROUND), 1283 MirrorCopyMode_str(current)); 1284 } 1285 } 1286 1287 static void mirror_query(BlockJob *job, BlockJobInfo *info) 1288 { 1289 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1290 1291 info->u.mirror = (BlockJobInfoMirror) { 1292 .actively_synced = qatomic_read(&s->actively_synced), 1293 }; 1294 } 1295 1296 static const BlockJobDriver mirror_job_driver = { 1297 .job_driver = { 1298 .instance_size = sizeof(MirrorBlockJob), 1299 .job_type = JOB_TYPE_MIRROR, 1300 .free = block_job_free, 1301 .user_resume = block_job_user_resume, 1302 .run = mirror_run, 1303 .prepare = mirror_prepare, 1304 .abort = mirror_abort, 1305 .pause = mirror_pause, 1306 .complete = mirror_complete, 1307 .cancel = mirror_cancel, 1308 }, 1309 .drained_poll = mirror_drained_poll, 1310 .change = mirror_change, 1311 .query = mirror_query, 1312 }; 1313 1314 static const BlockJobDriver commit_active_job_driver = { 1315 .job_driver = { 1316 .instance_size = sizeof(MirrorBlockJob), 1317 .job_type = JOB_TYPE_COMMIT, 1318 .free = block_job_free, 1319 .user_resume = block_job_user_resume, 1320 .run = mirror_run, 1321 .prepare = mirror_prepare, 1322 .abort = mirror_abort, 1323 .pause = mirror_pause, 1324 .complete = mirror_complete, 1325 .cancel = commit_active_cancel, 1326 }, 1327 .drained_poll = mirror_drained_poll, 1328 }; 1329 1330 static void coroutine_fn 1331 do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, 1332 uint64_t offset, uint64_t bytes, 1333 QEMUIOVector *qiov, int flags) 1334 { 1335 int ret; 1336 size_t qiov_offset = 0; 1337 int64_t bitmap_offset, bitmap_end; 1338 1339 if (!QEMU_IS_ALIGNED(offset, job->granularity) && 1340 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset)) 1341 { 1342 /* 1343 * Dirty unaligned padding: ignore it. 1344 * 1345 * Reasoning: 1346 * 1. If we copy it, we can't reset corresponding bit in 1347 * dirty_bitmap as there may be some "dirty" bytes still not 1348 * copied. 1349 * 2. It's already dirty, so skipping it we don't diverge mirror 1350 * progress. 1351 * 1352 * Note, that because of this, guest write may have no contribution 1353 * into mirror converge, but that's not bad, as we have background 1354 * process of mirroring. If under some bad circumstances (high guest 1355 * IO load) background process starve, we will not converge anyway, 1356 * even if each write will contribute, as guest is not guaranteed to 1357 * rewrite the whole disk. 1358 */ 1359 qiov_offset = QEMU_ALIGN_UP(offset, job->granularity) - offset; 1360 if (bytes <= qiov_offset) { 1361 /* nothing to do after shrink */ 1362 return; 1363 } 1364 offset += qiov_offset; 1365 bytes -= qiov_offset; 1366 } 1367 1368 if (!QEMU_IS_ALIGNED(offset + bytes, job->granularity) && 1369 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset + bytes - 1)) 1370 { 1371 uint64_t tail = (offset + bytes) % job->granularity; 1372 1373 if (bytes <= tail) { 1374 /* nothing to do after shrink */ 1375 return; 1376 } 1377 bytes -= tail; 1378 } 1379 1380 /* 1381 * Tails are either clean or shrunk, so for bitmap resetting 1382 * we safely align the range down. 1383 */ 1384 bitmap_offset = QEMU_ALIGN_UP(offset, job->granularity); 1385 bitmap_end = QEMU_ALIGN_DOWN(offset + bytes, job->granularity); 1386 if (bitmap_offset < bitmap_end) { 1387 bdrv_reset_dirty_bitmap(job->dirty_bitmap, bitmap_offset, 1388 bitmap_end - bitmap_offset); 1389 } 1390 1391 job_progress_increase_remaining(&job->common.job, bytes); 1392 job->active_write_bytes_in_flight += bytes; 1393 1394 switch (method) { 1395 case MIRROR_METHOD_COPY: 1396 ret = blk_co_pwritev_part(job->target, offset, bytes, 1397 qiov, qiov_offset, flags); 1398 break; 1399 1400 case MIRROR_METHOD_ZERO: 1401 assert(!qiov); 1402 ret = blk_co_pwrite_zeroes(job->target, offset, bytes, flags); 1403 break; 1404 1405 case MIRROR_METHOD_DISCARD: 1406 assert(!qiov); 1407 ret = blk_co_pdiscard(job->target, offset, bytes); 1408 break; 1409 1410 default: 1411 abort(); 1412 } 1413 1414 job->active_write_bytes_in_flight -= bytes; 1415 if (ret >= 0) { 1416 job_progress_update(&job->common.job, bytes); 1417 } else { 1418 BlockErrorAction action; 1419 1420 /* 1421 * We failed, so we should mark dirty the whole area, aligned up. 1422 * Note that we don't care about shrunk tails if any: they were dirty 1423 * at function start, and they must be still dirty, as we've locked 1424 * the region for in-flight op. 1425 */ 1426 bitmap_offset = QEMU_ALIGN_DOWN(offset, job->granularity); 1427 bitmap_end = QEMU_ALIGN_UP(offset + bytes, job->granularity); 1428 bdrv_set_dirty_bitmap(job->dirty_bitmap, bitmap_offset, 1429 bitmap_end - bitmap_offset); 1430 qatomic_set(&job->actively_synced, false); 1431 1432 action = mirror_error_action(job, false, -ret); 1433 if (action == BLOCK_ERROR_ACTION_REPORT) { 1434 if (!job->ret) { 1435 job->ret = ret; 1436 } 1437 } 1438 } 1439 } 1440 1441 static MirrorOp *coroutine_fn active_write_prepare(MirrorBlockJob *s, 1442 uint64_t offset, 1443 uint64_t bytes) 1444 { 1445 MirrorOp *op; 1446 uint64_t start_chunk = offset / s->granularity; 1447 uint64_t end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 1448 1449 op = g_new(MirrorOp, 1); 1450 *op = (MirrorOp){ 1451 .s = s, 1452 .offset = offset, 1453 .bytes = bytes, 1454 .is_active_write = true, 1455 .is_in_flight = true, 1456 .co = qemu_coroutine_self(), 1457 }; 1458 qemu_co_queue_init(&op->waiting_requests); 1459 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 1460 1461 s->in_active_write_counter++; 1462 1463 /* 1464 * Wait for concurrent requests affecting the area. If there are already 1465 * running requests that are copying off now-to-be stale data in the area, 1466 * we must wait for them to finish before we begin writing fresh data to the 1467 * target so that the write operations appear in the correct order. 1468 * Note that background requests (see mirror_iteration()) in contrast only 1469 * wait for conflicting requests at the start of the dirty area, and then 1470 * (based on the in_flight_bitmap) truncate the area to copy so it will not 1471 * conflict with any requests beyond that. For active writes, however, we 1472 * cannot truncate that area. The request from our parent must be blocked 1473 * until the area is copied in full. Therefore, we must wait for the whole 1474 * area to become free of concurrent requests. 1475 */ 1476 mirror_wait_on_conflicts(op, s, offset, bytes); 1477 1478 bitmap_set(s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1479 1480 return op; 1481 } 1482 1483 static void coroutine_fn GRAPH_RDLOCK active_write_settle(MirrorOp *op) 1484 { 1485 uint64_t start_chunk = op->offset / op->s->granularity; 1486 uint64_t end_chunk = DIV_ROUND_UP(op->offset + op->bytes, 1487 op->s->granularity); 1488 1489 if (!--op->s->in_active_write_counter && 1490 qatomic_read(&op->s->actively_synced)) { 1491 BdrvChild *source = op->s->mirror_top_bs->backing; 1492 1493 if (QLIST_FIRST(&source->bs->parents) == source && 1494 QLIST_NEXT(source, next_parent) == NULL) 1495 { 1496 /* Assert that we are back in sync once all active write 1497 * operations are settled. 1498 * Note that we can only assert this if the mirror node 1499 * is the source node's only parent. */ 1500 assert(!bdrv_get_dirty_count(op->s->dirty_bitmap)); 1501 } 1502 } 1503 bitmap_clear(op->s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1504 QTAILQ_REMOVE(&op->s->ops_in_flight, op, next); 1505 qemu_co_queue_restart_all(&op->waiting_requests); 1506 g_free(op); 1507 } 1508 1509 static int coroutine_fn GRAPH_RDLOCK 1510 bdrv_mirror_top_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes, 1511 QEMUIOVector *qiov, BdrvRequestFlags flags) 1512 { 1513 return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); 1514 } 1515 1516 static bool should_copy_to_target(MirrorBDSOpaque *s) 1517 { 1518 return s->job && s->job->ret >= 0 && 1519 !job_is_cancelled(&s->job->common.job) && 1520 qatomic_read(&s->job->copy_mode) == MIRROR_COPY_MODE_WRITE_BLOCKING; 1521 } 1522 1523 static int coroutine_fn GRAPH_RDLOCK 1524 bdrv_mirror_top_do_write(BlockDriverState *bs, MirrorMethod method, 1525 bool copy_to_target, uint64_t offset, uint64_t bytes, 1526 QEMUIOVector *qiov, int flags) 1527 { 1528 MirrorOp *op = NULL; 1529 MirrorBDSOpaque *s = bs->opaque; 1530 int ret = 0; 1531 1532 if (copy_to_target) { 1533 op = active_write_prepare(s->job, offset, bytes); 1534 } 1535 1536 switch (method) { 1537 case MIRROR_METHOD_COPY: 1538 ret = bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags); 1539 break; 1540 1541 case MIRROR_METHOD_ZERO: 1542 ret = bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags); 1543 break; 1544 1545 case MIRROR_METHOD_DISCARD: 1546 ret = bdrv_co_pdiscard(bs->backing, offset, bytes); 1547 break; 1548 1549 default: 1550 abort(); 1551 } 1552 1553 if (!copy_to_target && s->job && s->job->dirty_bitmap) { 1554 qatomic_set(&s->job->actively_synced, false); 1555 bdrv_set_dirty_bitmap(s->job->dirty_bitmap, offset, bytes); 1556 } 1557 1558 if (ret < 0) { 1559 goto out; 1560 } 1561 1562 if (copy_to_target) { 1563 do_sync_target_write(s->job, method, offset, bytes, qiov, flags); 1564 } 1565 1566 out: 1567 if (copy_to_target) { 1568 active_write_settle(op); 1569 } 1570 return ret; 1571 } 1572 1573 static int coroutine_fn GRAPH_RDLOCK 1574 bdrv_mirror_top_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes, 1575 QEMUIOVector *qiov, BdrvRequestFlags flags) 1576 { 1577 QEMUIOVector bounce_qiov; 1578 void *bounce_buf; 1579 int ret = 0; 1580 bool copy_to_target = should_copy_to_target(bs->opaque); 1581 1582 if (copy_to_target) { 1583 /* The guest might concurrently modify the data to write; but 1584 * the data on source and destination must match, so we have 1585 * to use a bounce buffer if we are going to write to the 1586 * target now. */ 1587 bounce_buf = qemu_blockalign(bs, bytes); 1588 iov_to_buf_full(qiov->iov, qiov->niov, 0, bounce_buf, bytes); 1589 1590 qemu_iovec_init(&bounce_qiov, 1); 1591 qemu_iovec_add(&bounce_qiov, bounce_buf, bytes); 1592 qiov = &bounce_qiov; 1593 1594 flags &= ~BDRV_REQ_REGISTERED_BUF; 1595 } 1596 1597 ret = bdrv_mirror_top_do_write(bs, MIRROR_METHOD_COPY, copy_to_target, 1598 offset, bytes, qiov, flags); 1599 1600 if (copy_to_target) { 1601 qemu_iovec_destroy(&bounce_qiov); 1602 qemu_vfree(bounce_buf); 1603 } 1604 1605 return ret; 1606 } 1607 1608 static int coroutine_fn GRAPH_RDLOCK bdrv_mirror_top_flush(BlockDriverState *bs) 1609 { 1610 if (bs->backing == NULL) { 1611 /* we can be here after failed bdrv_append in mirror_start_job */ 1612 return 0; 1613 } 1614 return bdrv_co_flush(bs->backing->bs); 1615 } 1616 1617 static int coroutine_fn GRAPH_RDLOCK 1618 bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs, int64_t offset, 1619 int64_t bytes, BdrvRequestFlags flags) 1620 { 1621 bool copy_to_target = should_copy_to_target(bs->opaque); 1622 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_ZERO, copy_to_target, 1623 offset, bytes, NULL, flags); 1624 } 1625 1626 static int coroutine_fn GRAPH_RDLOCK 1627 bdrv_mirror_top_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes) 1628 { 1629 bool copy_to_target = should_copy_to_target(bs->opaque); 1630 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_DISCARD, copy_to_target, 1631 offset, bytes, NULL, 0); 1632 } 1633 1634 static void GRAPH_RDLOCK bdrv_mirror_top_refresh_filename(BlockDriverState *bs) 1635 { 1636 if (bs->backing == NULL) { 1637 /* we can be here after failed bdrv_attach_child in 1638 * bdrv_set_backing_hd */ 1639 return; 1640 } 1641 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), 1642 bs->backing->bs->filename); 1643 } 1644 1645 static void bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c, 1646 BdrvChildRole role, 1647 BlockReopenQueue *reopen_queue, 1648 uint64_t perm, uint64_t shared, 1649 uint64_t *nperm, uint64_t *nshared) 1650 { 1651 MirrorBDSOpaque *s = bs->opaque; 1652 1653 if (s->stop) { 1654 /* 1655 * If the job is to be stopped, we do not need to forward 1656 * anything to the real image. 1657 */ 1658 *nperm = 0; 1659 *nshared = BLK_PERM_ALL; 1660 return; 1661 } 1662 1663 bdrv_default_perms(bs, c, role, reopen_queue, 1664 perm, shared, nperm, nshared); 1665 1666 if (s->is_commit) { 1667 /* 1668 * For commit jobs, we cannot take CONSISTENT_READ, because 1669 * that permission is unshared for everything above the base 1670 * node (except for filters on the base node). 1671 * We also have to force-share the WRITE permission, or 1672 * otherwise we would block ourselves at the base node (if 1673 * writes are blocked for a node, they are also blocked for 1674 * its backing file). 1675 * (We could also share RESIZE, because it may be needed for 1676 * the target if its size is less than the top node's; but 1677 * bdrv_default_perms_for_cow() automatically shares RESIZE 1678 * for backing nodes if WRITE is shared, so there is no need 1679 * to do it here.) 1680 */ 1681 *nperm &= ~BLK_PERM_CONSISTENT_READ; 1682 *nshared |= BLK_PERM_WRITE; 1683 } 1684 } 1685 1686 /* Dummy node that provides consistent read to its users without requiring it 1687 * from its backing file and that allows writes on the backing file chain. */ 1688 static BlockDriver bdrv_mirror_top = { 1689 .format_name = "mirror_top", 1690 .bdrv_co_preadv = bdrv_mirror_top_preadv, 1691 .bdrv_co_pwritev = bdrv_mirror_top_pwritev, 1692 .bdrv_co_pwrite_zeroes = bdrv_mirror_top_pwrite_zeroes, 1693 .bdrv_co_pdiscard = bdrv_mirror_top_pdiscard, 1694 .bdrv_co_flush = bdrv_mirror_top_flush, 1695 .bdrv_refresh_filename = bdrv_mirror_top_refresh_filename, 1696 .bdrv_child_perm = bdrv_mirror_top_child_perm, 1697 1698 .is_filter = true, 1699 .filtered_child_is_backing = true, 1700 }; 1701 1702 static BlockJob *mirror_start_job( 1703 const char *job_id, BlockDriverState *bs, 1704 int creation_flags, BlockDriverState *target, 1705 const char *replaces, int64_t speed, 1706 uint32_t granularity, int64_t buf_size, 1707 BlockMirrorBackingMode backing_mode, 1708 bool zero_target, 1709 BlockdevOnError on_source_error, 1710 BlockdevOnError on_target_error, 1711 bool unmap, 1712 BlockCompletionFunc *cb, 1713 void *opaque, 1714 const BlockJobDriver *driver, 1715 bool is_none_mode, BlockDriverState *base, 1716 bool auto_complete, const char *filter_node_name, 1717 bool is_mirror, MirrorCopyMode copy_mode, 1718 Error **errp) 1719 { 1720 MirrorBlockJob *s; 1721 MirrorBDSOpaque *bs_opaque; 1722 BlockDriverState *mirror_top_bs; 1723 bool target_is_backing; 1724 uint64_t target_perms, target_shared_perms; 1725 int ret; 1726 1727 GLOBAL_STATE_CODE(); 1728 1729 if (granularity == 0) { 1730 granularity = bdrv_get_default_bitmap_granularity(target); 1731 } 1732 1733 assert(is_power_of_2(granularity)); 1734 1735 if (buf_size < 0) { 1736 error_setg(errp, "Invalid parameter 'buf-size'"); 1737 return NULL; 1738 } 1739 1740 if (buf_size == 0) { 1741 buf_size = DEFAULT_MIRROR_BUF_SIZE; 1742 } 1743 1744 bdrv_graph_rdlock_main_loop(); 1745 if (bdrv_skip_filters(bs) == bdrv_skip_filters(target)) { 1746 error_setg(errp, "Can't mirror node into itself"); 1747 bdrv_graph_rdunlock_main_loop(); 1748 return NULL; 1749 } 1750 1751 target_is_backing = bdrv_chain_contains(bs, target); 1752 bdrv_graph_rdunlock_main_loop(); 1753 1754 /* In the case of active commit, add dummy driver to provide consistent 1755 * reads on the top, while disabling it in the intermediate nodes, and make 1756 * the backing chain writable. */ 1757 mirror_top_bs = bdrv_new_open_driver(&bdrv_mirror_top, filter_node_name, 1758 BDRV_O_RDWR, errp); 1759 if (mirror_top_bs == NULL) { 1760 return NULL; 1761 } 1762 if (!filter_node_name) { 1763 mirror_top_bs->implicit = true; 1764 } 1765 1766 /* So that we can always drop this node */ 1767 mirror_top_bs->never_freeze = true; 1768 1769 mirror_top_bs->total_sectors = bs->total_sectors; 1770 mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED; 1771 mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED | 1772 BDRV_REQ_NO_FALLBACK; 1773 bs_opaque = g_new0(MirrorBDSOpaque, 1); 1774 mirror_top_bs->opaque = bs_opaque; 1775 1776 bs_opaque->is_commit = target_is_backing; 1777 1778 bdrv_drained_begin(bs); 1779 ret = bdrv_append(mirror_top_bs, bs, errp); 1780 bdrv_drained_end(bs); 1781 1782 if (ret < 0) { 1783 bdrv_unref(mirror_top_bs); 1784 return NULL; 1785 } 1786 1787 /* Make sure that the source is not resized while the job is running */ 1788 s = block_job_create(job_id, driver, NULL, mirror_top_bs, 1789 BLK_PERM_CONSISTENT_READ, 1790 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | 1791 BLK_PERM_WRITE, speed, 1792 creation_flags, cb, opaque, errp); 1793 if (!s) { 1794 goto fail; 1795 } 1796 1797 /* The block job now has a reference to this node */ 1798 bdrv_unref(mirror_top_bs); 1799 1800 s->mirror_top_bs = mirror_top_bs; 1801 1802 /* No resize for the target either; while the mirror is still running, a 1803 * consistent read isn't necessarily possible. We could possibly allow 1804 * writes and graph modifications, though it would likely defeat the 1805 * purpose of a mirror, so leave them blocked for now. 1806 * 1807 * In the case of active commit, things look a bit different, though, 1808 * because the target is an already populated backing file in active use. 1809 * We can allow anything except resize there.*/ 1810 1811 target_perms = BLK_PERM_WRITE; 1812 target_shared_perms = BLK_PERM_WRITE_UNCHANGED; 1813 1814 if (target_is_backing) { 1815 int64_t bs_size, target_size; 1816 bs_size = bdrv_getlength(bs); 1817 if (bs_size < 0) { 1818 error_setg_errno(errp, -bs_size, 1819 "Could not inquire top image size"); 1820 goto fail; 1821 } 1822 1823 target_size = bdrv_getlength(target); 1824 if (target_size < 0) { 1825 error_setg_errno(errp, -target_size, 1826 "Could not inquire base image size"); 1827 goto fail; 1828 } 1829 1830 if (target_size < bs_size) { 1831 target_perms |= BLK_PERM_RESIZE; 1832 } 1833 1834 target_shared_perms |= BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE; 1835 } else { 1836 bdrv_graph_rdlock_main_loop(); 1837 if (bdrv_chain_contains(bs, bdrv_skip_filters(target))) { 1838 /* 1839 * We may want to allow this in the future, but it would 1840 * require taking some extra care. 1841 */ 1842 error_setg(errp, "Cannot mirror to a filter on top of a node in " 1843 "the source's backing chain"); 1844 bdrv_graph_rdunlock_main_loop(); 1845 goto fail; 1846 } 1847 bdrv_graph_rdunlock_main_loop(); 1848 } 1849 1850 s->target = blk_new(s->common.job.aio_context, 1851 target_perms, target_shared_perms); 1852 ret = blk_insert_bs(s->target, target, errp); 1853 if (ret < 0) { 1854 goto fail; 1855 } 1856 if (is_mirror) { 1857 /* XXX: Mirror target could be a NBD server of target QEMU in the case 1858 * of non-shared block migration. To allow migration completion, we 1859 * have to allow "inactivate" of the target BB. When that happens, we 1860 * know the job is drained, and the vcpus are stopped, so no write 1861 * operation will be performed. Block layer already has assertions to 1862 * ensure that. */ 1863 blk_set_force_allow_inactivate(s->target); 1864 } 1865 blk_set_allow_aio_context_change(s->target, true); 1866 blk_set_disable_request_queuing(s->target, true); 1867 1868 bdrv_graph_rdlock_main_loop(); 1869 s->replaces = g_strdup(replaces); 1870 s->on_source_error = on_source_error; 1871 s->on_target_error = on_target_error; 1872 s->is_none_mode = is_none_mode; 1873 s->backing_mode = backing_mode; 1874 s->zero_target = zero_target; 1875 qatomic_set(&s->copy_mode, copy_mode); 1876 s->base = base; 1877 s->base_overlay = bdrv_find_overlay(bs, base); 1878 s->granularity = granularity; 1879 s->buf_size = ROUND_UP(buf_size, granularity); 1880 s->unmap = unmap; 1881 if (auto_complete) { 1882 s->should_complete = true; 1883 } 1884 bdrv_graph_rdunlock_main_loop(); 1885 1886 s->dirty_bitmap = bdrv_create_dirty_bitmap(s->mirror_top_bs, granularity, 1887 NULL, errp); 1888 if (!s->dirty_bitmap) { 1889 goto fail; 1890 } 1891 1892 /* 1893 * The dirty bitmap is set by bdrv_mirror_top_do_write() when not in active 1894 * mode. 1895 */ 1896 bdrv_disable_dirty_bitmap(s->dirty_bitmap); 1897 1898 bdrv_graph_wrlock(); 1899 ret = block_job_add_bdrv(&s->common, "source", bs, 0, 1900 BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE | 1901 BLK_PERM_CONSISTENT_READ, 1902 errp); 1903 if (ret < 0) { 1904 bdrv_graph_wrunlock(); 1905 goto fail; 1906 } 1907 1908 /* Required permissions are already taken with blk_new() */ 1909 block_job_add_bdrv(&s->common, "target", target, 0, BLK_PERM_ALL, 1910 &error_abort); 1911 1912 /* In commit_active_start() all intermediate nodes disappear, so 1913 * any jobs in them must be blocked */ 1914 if (target_is_backing) { 1915 BlockDriverState *iter, *filtered_target; 1916 uint64_t iter_shared_perms; 1917 1918 /* 1919 * The topmost node with 1920 * bdrv_skip_filters(filtered_target) == bdrv_skip_filters(target) 1921 */ 1922 filtered_target = bdrv_cow_bs(bdrv_find_overlay(bs, target)); 1923 1924 assert(bdrv_skip_filters(filtered_target) == 1925 bdrv_skip_filters(target)); 1926 1927 /* 1928 * XXX BLK_PERM_WRITE needs to be allowed so we don't block 1929 * ourselves at s->base (if writes are blocked for a node, they are 1930 * also blocked for its backing file). The other options would be a 1931 * second filter driver above s->base (== target). 1932 */ 1933 iter_shared_perms = BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE; 1934 1935 for (iter = bdrv_filter_or_cow_bs(bs); iter != target; 1936 iter = bdrv_filter_or_cow_bs(iter)) 1937 { 1938 if (iter == filtered_target) { 1939 /* 1940 * From here on, all nodes are filters on the base. 1941 * This allows us to share BLK_PERM_CONSISTENT_READ. 1942 */ 1943 iter_shared_perms |= BLK_PERM_CONSISTENT_READ; 1944 } 1945 1946 ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, 1947 iter_shared_perms, errp); 1948 if (ret < 0) { 1949 bdrv_graph_wrunlock(); 1950 goto fail; 1951 } 1952 } 1953 1954 if (bdrv_freeze_backing_chain(mirror_top_bs, target, errp) < 0) { 1955 bdrv_graph_wrunlock(); 1956 goto fail; 1957 } 1958 } 1959 bdrv_graph_wrunlock(); 1960 1961 QTAILQ_INIT(&s->ops_in_flight); 1962 1963 trace_mirror_start(bs, s, opaque); 1964 job_start(&s->common.job); 1965 1966 return &s->common; 1967 1968 fail: 1969 if (s) { 1970 /* Make sure this BDS does not go away until we have completed the graph 1971 * changes below */ 1972 bdrv_ref(mirror_top_bs); 1973 1974 g_free(s->replaces); 1975 blk_unref(s->target); 1976 bs_opaque->job = NULL; 1977 if (s->dirty_bitmap) { 1978 bdrv_release_dirty_bitmap(s->dirty_bitmap); 1979 } 1980 job_early_fail(&s->common.job); 1981 } 1982 1983 bs_opaque->stop = true; 1984 bdrv_drained_begin(bs); 1985 bdrv_graph_wrlock(); 1986 assert(mirror_top_bs->backing->bs == bs); 1987 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 1988 &error_abort); 1989 bdrv_replace_node(mirror_top_bs, bs, &error_abort); 1990 bdrv_graph_wrunlock(); 1991 bdrv_drained_end(bs); 1992 1993 bdrv_unref(mirror_top_bs); 1994 1995 return NULL; 1996 } 1997 1998 void mirror_start(const char *job_id, BlockDriverState *bs, 1999 BlockDriverState *target, const char *replaces, 2000 int creation_flags, int64_t speed, 2001 uint32_t granularity, int64_t buf_size, 2002 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, 2003 bool zero_target, 2004 BlockdevOnError on_source_error, 2005 BlockdevOnError on_target_error, 2006 bool unmap, const char *filter_node_name, 2007 MirrorCopyMode copy_mode, Error **errp) 2008 { 2009 bool is_none_mode; 2010 BlockDriverState *base; 2011 2012 GLOBAL_STATE_CODE(); 2013 2014 if ((mode == MIRROR_SYNC_MODE_INCREMENTAL) || 2015 (mode == MIRROR_SYNC_MODE_BITMAP)) { 2016 error_setg(errp, "Sync mode '%s' not supported", 2017 MirrorSyncMode_str(mode)); 2018 return; 2019 } 2020 2021 bdrv_graph_rdlock_main_loop(); 2022 is_none_mode = mode == MIRROR_SYNC_MODE_NONE; 2023 base = mode == MIRROR_SYNC_MODE_TOP ? bdrv_backing_chain_next(bs) : NULL; 2024 bdrv_graph_rdunlock_main_loop(); 2025 2026 mirror_start_job(job_id, bs, creation_flags, target, replaces, 2027 speed, granularity, buf_size, backing_mode, zero_target, 2028 on_source_error, on_target_error, unmap, NULL, NULL, 2029 &mirror_job_driver, is_none_mode, base, false, 2030 filter_node_name, true, copy_mode, errp); 2031 } 2032 2033 BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs, 2034 BlockDriverState *base, int creation_flags, 2035 int64_t speed, BlockdevOnError on_error, 2036 const char *filter_node_name, 2037 BlockCompletionFunc *cb, void *opaque, 2038 bool auto_complete, Error **errp) 2039 { 2040 bool base_read_only; 2041 BlockJob *job; 2042 2043 GLOBAL_STATE_CODE(); 2044 2045 base_read_only = bdrv_is_read_only(base); 2046 2047 if (base_read_only) { 2048 if (bdrv_reopen_set_read_only(base, false, errp) < 0) { 2049 return NULL; 2050 } 2051 } 2052 2053 job = mirror_start_job( 2054 job_id, bs, creation_flags, base, NULL, speed, 0, 0, 2055 MIRROR_LEAVE_BACKING_CHAIN, false, 2056 on_error, on_error, true, cb, opaque, 2057 &commit_active_job_driver, false, base, auto_complete, 2058 filter_node_name, false, MIRROR_COPY_MODE_BACKGROUND, 2059 errp); 2060 if (!job) { 2061 goto error_restore_flags; 2062 } 2063 2064 return job; 2065 2066 error_restore_flags: 2067 /* ignore error and errp for bdrv_reopen, because we want to propagate 2068 * the original error */ 2069 if (base_read_only) { 2070 bdrv_reopen_set_read_only(base, true, NULL); 2071 } 2072 return NULL; 2073 } 2074