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 "system/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 MirrorSyncMode sync_mode; 55 BlockMirrorBackingMode backing_mode; 56 /* Whether the target should be assumed to be already zero initialized */ 57 bool target_is_zero; 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 unsigned long *zero_bitmap; 77 BdrvDirtyBitmap *dirty_bitmap; 78 BdrvDirtyBitmapIter *dbi; 79 uint8_t *buf; 80 QSIMPLEQ_HEAD(, MirrorBuffer) buf_free; 81 int buf_free_count; 82 83 uint64_t last_pause_ns; 84 unsigned long *in_flight_bitmap; 85 unsigned in_flight; 86 int64_t bytes_in_flight; 87 QTAILQ_HEAD(, MirrorOp) ops_in_flight; 88 int ret; 89 bool unmap; 90 int target_cluster_size; 91 int max_iov; 92 bool initial_zeroing_ongoing; 93 int in_active_write_counter; 94 int64_t active_write_bytes_in_flight; 95 bool prepared; 96 bool in_drain; 97 bool base_ro; 98 } MirrorBlockJob; 99 100 typedef struct MirrorBDSOpaque { 101 MirrorBlockJob *job; 102 bool stop; 103 bool is_commit; 104 } MirrorBDSOpaque; 105 106 struct MirrorOp { 107 MirrorBlockJob *s; 108 QEMUIOVector qiov; 109 int64_t offset; 110 uint64_t bytes; 111 112 /* 113 * These pointers are set by mirror_co_read(), mirror_co_zero(), and 114 * mirror_co_discard() before yielding for the first time 115 */ 116 int64_t *bytes_handled; 117 bool *io_skipped; 118 119 bool is_pseudo_op; 120 bool is_active_write; 121 bool is_in_flight; 122 CoQueue waiting_requests; 123 Coroutine *co; 124 MirrorOp *waiting_for_op; 125 126 QTAILQ_ENTRY(MirrorOp) next; 127 }; 128 129 typedef enum MirrorMethod { 130 MIRROR_METHOD_COPY, 131 MIRROR_METHOD_ZERO, 132 MIRROR_METHOD_DISCARD, 133 } MirrorMethod; 134 135 static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, 136 int error) 137 { 138 qatomic_set(&s->actively_synced, false); 139 if (read) { 140 return block_job_error_action(&s->common, s->on_source_error, 141 true, error); 142 } else { 143 return block_job_error_action(&s->common, s->on_target_error, 144 false, error); 145 } 146 } 147 148 static void coroutine_fn mirror_wait_on_conflicts(MirrorOp *self, 149 MirrorBlockJob *s, 150 uint64_t offset, 151 uint64_t bytes) 152 { 153 uint64_t self_start_chunk = offset / s->granularity; 154 uint64_t self_end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 155 uint64_t self_nb_chunks = self_end_chunk - self_start_chunk; 156 157 while (find_next_bit(s->in_flight_bitmap, self_end_chunk, 158 self_start_chunk) < self_end_chunk && 159 s->ret >= 0) 160 { 161 MirrorOp *op; 162 163 QTAILQ_FOREACH(op, &s->ops_in_flight, next) { 164 uint64_t op_start_chunk = op->offset / s->granularity; 165 uint64_t op_nb_chunks = DIV_ROUND_UP(op->offset + op->bytes, 166 s->granularity) - 167 op_start_chunk; 168 169 if (op == self) { 170 continue; 171 } 172 173 if (ranges_overlap(self_start_chunk, self_nb_chunks, 174 op_start_chunk, op_nb_chunks)) 175 { 176 if (self) { 177 /* 178 * If the operation is already (indirectly) waiting for us, 179 * or will wait for us as soon as it wakes up, then just go 180 * on (instead of producing a deadlock in the former case). 181 */ 182 if (op->waiting_for_op) { 183 continue; 184 } 185 186 self->waiting_for_op = op; 187 } 188 189 qemu_co_queue_wait(&op->waiting_requests, NULL); 190 191 if (self) { 192 self->waiting_for_op = NULL; 193 } 194 195 break; 196 } 197 } 198 } 199 } 200 201 static void coroutine_fn mirror_iteration_done(MirrorOp *op, int ret) 202 { 203 MirrorBlockJob *s = op->s; 204 struct iovec *iov; 205 int64_t chunk_num; 206 int i, nb_chunks; 207 208 trace_mirror_iteration_done(s, op->offset, op->bytes, ret); 209 210 s->in_flight--; 211 s->bytes_in_flight -= op->bytes; 212 iov = op->qiov.iov; 213 for (i = 0; i < op->qiov.niov; i++) { 214 MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base; 215 QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next); 216 s->buf_free_count++; 217 } 218 219 chunk_num = op->offset / s->granularity; 220 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity); 221 222 bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks); 223 QTAILQ_REMOVE(&s->ops_in_flight, op, next); 224 if (ret >= 0) { 225 if (s->cow_bitmap) { 226 bitmap_set(s->cow_bitmap, chunk_num, nb_chunks); 227 } 228 if (!s->initial_zeroing_ongoing) { 229 job_progress_update(&s->common.job, op->bytes); 230 } 231 } 232 qemu_iovec_destroy(&op->qiov); 233 234 qemu_co_queue_restart_all(&op->waiting_requests); 235 g_free(op); 236 } 237 238 static void coroutine_fn mirror_write_complete(MirrorOp *op, int ret) 239 { 240 MirrorBlockJob *s = op->s; 241 242 if (ret < 0) { 243 BlockErrorAction action; 244 245 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes); 246 action = mirror_error_action(s, false, -ret); 247 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 248 s->ret = ret; 249 } 250 } 251 252 mirror_iteration_done(op, ret); 253 } 254 255 static void coroutine_fn mirror_read_complete(MirrorOp *op, int ret) 256 { 257 MirrorBlockJob *s = op->s; 258 259 if (ret < 0) { 260 BlockErrorAction action; 261 262 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes); 263 action = mirror_error_action(s, true, -ret); 264 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 265 s->ret = ret; 266 } 267 268 mirror_iteration_done(op, ret); 269 return; 270 } 271 272 ret = blk_co_pwritev(s->target, op->offset, op->qiov.size, &op->qiov, 0); 273 mirror_write_complete(op, ret); 274 } 275 276 /* Clip bytes relative to offset to not exceed end-of-file */ 277 static inline int64_t mirror_clip_bytes(MirrorBlockJob *s, 278 int64_t offset, 279 int64_t bytes) 280 { 281 return MIN(bytes, s->bdev_length - offset); 282 } 283 284 /* Round offset and/or bytes to target cluster if COW is needed, and 285 * return the offset of the adjusted tail against original. */ 286 static int coroutine_fn mirror_cow_align(MirrorBlockJob *s, int64_t *offset, 287 uint64_t *bytes) 288 { 289 bool need_cow; 290 int ret = 0; 291 int64_t align_offset = *offset; 292 int64_t align_bytes = *bytes; 293 int max_bytes = s->granularity * s->max_iov; 294 295 need_cow = !test_bit(*offset / s->granularity, s->cow_bitmap); 296 need_cow |= !test_bit((*offset + *bytes - 1) / s->granularity, 297 s->cow_bitmap); 298 if (need_cow) { 299 bdrv_round_to_subclusters(blk_bs(s->target), *offset, *bytes, 300 &align_offset, &align_bytes); 301 } 302 303 if (align_bytes > max_bytes) { 304 align_bytes = max_bytes; 305 if (need_cow) { 306 align_bytes = QEMU_ALIGN_DOWN(align_bytes, s->target_cluster_size); 307 } 308 } 309 /* Clipping may result in align_bytes unaligned to chunk boundary, but 310 * that doesn't matter because it's already the end of source image. */ 311 align_bytes = mirror_clip_bytes(s, align_offset, align_bytes); 312 313 ret = align_offset + align_bytes - (*offset + *bytes); 314 *offset = align_offset; 315 *bytes = align_bytes; 316 assert(ret >= 0); 317 return ret; 318 } 319 320 static inline void coroutine_fn 321 mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s) 322 { 323 MirrorOp *op; 324 325 QTAILQ_FOREACH(op, &s->ops_in_flight, next) { 326 /* 327 * Do not wait on pseudo ops, because it may in turn wait on 328 * some other operation to start, which may in fact be the 329 * caller of this function. Since there is only one pseudo op 330 * at any given time, we will always find some real operation 331 * to wait on. 332 * Also, do not wait on active operations, because they do not 333 * use up in-flight slots. 334 */ 335 if (!op->is_pseudo_op && op->is_in_flight && !op->is_active_write) { 336 qemu_co_queue_wait(&op->waiting_requests, NULL); 337 return; 338 } 339 } 340 abort(); 341 } 342 343 /* Perform a mirror copy operation. 344 * 345 * *op->bytes_handled is set to the number of bytes copied after and 346 * including offset, excluding any bytes copied prior to offset due 347 * to alignment. This will be op->bytes if no alignment is necessary, 348 * or (new_end - op->offset) if the tail is rounded up or down due to 349 * alignment or buffer limit. 350 */ 351 static void coroutine_fn mirror_co_read(void *opaque) 352 { 353 MirrorOp *op = opaque; 354 MirrorBlockJob *s = op->s; 355 int nb_chunks; 356 int ret = -1; 357 uint64_t max_bytes; 358 359 max_bytes = s->granularity * s->max_iov; 360 361 /* We can only handle as much as buf_size at a time. */ 362 op->bytes = MIN(s->buf_size, MIN(max_bytes, op->bytes)); 363 assert(op->bytes); 364 assert(op->bytes < BDRV_REQUEST_MAX_BYTES); 365 *op->bytes_handled = op->bytes; 366 367 if (s->cow_bitmap) { 368 *op->bytes_handled += mirror_cow_align(s, &op->offset, &op->bytes); 369 } 370 /* Cannot exceed BDRV_REQUEST_MAX_BYTES + INT_MAX */ 371 assert(*op->bytes_handled <= UINT_MAX); 372 assert(op->bytes <= s->buf_size); 373 /* The offset is granularity-aligned because: 374 * 1) Caller passes in aligned values; 375 * 2) mirror_cow_align is used only when target cluster is larger. */ 376 assert(QEMU_IS_ALIGNED(op->offset, s->granularity)); 377 /* The range is sector-aligned, since bdrv_getlength() rounds up. */ 378 assert(QEMU_IS_ALIGNED(op->bytes, BDRV_SECTOR_SIZE)); 379 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity); 380 381 while (s->buf_free_count < nb_chunks) { 382 trace_mirror_yield_in_flight(s, op->offset, s->in_flight); 383 mirror_wait_for_free_in_flight_slot(s); 384 } 385 386 /* Now make a QEMUIOVector taking enough granularity-sized chunks 387 * from s->buf_free. 388 */ 389 qemu_iovec_init(&op->qiov, nb_chunks); 390 while (nb_chunks-- > 0) { 391 MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free); 392 size_t remaining = op->bytes - op->qiov.size; 393 394 QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next); 395 s->buf_free_count--; 396 qemu_iovec_add(&op->qiov, buf, MIN(s->granularity, remaining)); 397 } 398 399 /* Copy the dirty cluster. */ 400 s->in_flight++; 401 s->bytes_in_flight += op->bytes; 402 op->is_in_flight = true; 403 trace_mirror_one_iteration(s, op->offset, op->bytes); 404 405 WITH_GRAPH_RDLOCK_GUARD() { 406 ret = bdrv_co_preadv(s->mirror_top_bs->backing, op->offset, op->bytes, 407 &op->qiov, 0); 408 } 409 mirror_read_complete(op, ret); 410 } 411 412 static void coroutine_fn mirror_co_zero(void *opaque) 413 { 414 MirrorOp *op = opaque; 415 bool write_needed = true; 416 int ret = 0; 417 418 op->s->in_flight++; 419 op->s->bytes_in_flight += op->bytes; 420 *op->bytes_handled = op->bytes; 421 op->is_in_flight = true; 422 423 if (op->s->zero_bitmap) { 424 unsigned long end = DIV_ROUND_UP(op->offset + op->bytes, 425 op->s->granularity); 426 assert(QEMU_IS_ALIGNED(op->offset, op->s->granularity)); 427 assert(QEMU_IS_ALIGNED(op->bytes, op->s->granularity) || 428 op->offset + op->bytes == op->s->bdev_length); 429 if (find_next_zero_bit(op->s->zero_bitmap, end, 430 op->offset / op->s->granularity) == end) { 431 write_needed = false; 432 *op->io_skipped = true; 433 } 434 } 435 if (write_needed) { 436 ret = blk_co_pwrite_zeroes(op->s->target, op->offset, op->bytes, 437 op->s->unmap ? BDRV_REQ_MAY_UNMAP : 0); 438 } 439 if (ret >= 0 && op->s->zero_bitmap) { 440 bitmap_set(op->s->zero_bitmap, op->offset / op->s->granularity, 441 DIV_ROUND_UP(op->bytes, op->s->granularity)); 442 } 443 mirror_write_complete(op, ret); 444 } 445 446 static void coroutine_fn mirror_co_discard(void *opaque) 447 { 448 MirrorOp *op = opaque; 449 int ret; 450 451 op->s->in_flight++; 452 op->s->bytes_in_flight += op->bytes; 453 *op->bytes_handled = op->bytes; 454 op->is_in_flight = true; 455 456 ret = blk_co_pdiscard(op->s->target, op->offset, op->bytes); 457 mirror_write_complete(op, ret); 458 } 459 460 static unsigned mirror_perform(MirrorBlockJob *s, int64_t offset, 461 unsigned bytes, MirrorMethod mirror_method, 462 bool *io_skipped) 463 { 464 MirrorOp *op; 465 Coroutine *co; 466 int64_t bytes_handled = -1; 467 468 assert(QEMU_IS_ALIGNED(offset, s->granularity)); 469 assert(QEMU_IS_ALIGNED(bytes, s->granularity) || 470 offset + bytes == s->bdev_length); 471 op = g_new(MirrorOp, 1); 472 *op = (MirrorOp){ 473 .s = s, 474 .offset = offset, 475 .bytes = bytes, 476 .bytes_handled = &bytes_handled, 477 .io_skipped = io_skipped, 478 }; 479 qemu_co_queue_init(&op->waiting_requests); 480 481 switch (mirror_method) { 482 case MIRROR_METHOD_COPY: 483 if (s->zero_bitmap) { 484 bitmap_clear(s->zero_bitmap, offset / s->granularity, 485 DIV_ROUND_UP(bytes, s->granularity)); 486 } 487 co = qemu_coroutine_create(mirror_co_read, op); 488 break; 489 case MIRROR_METHOD_ZERO: 490 /* s->zero_bitmap handled in mirror_co_zero */ 491 co = qemu_coroutine_create(mirror_co_zero, op); 492 break; 493 case MIRROR_METHOD_DISCARD: 494 if (s->zero_bitmap) { 495 bitmap_clear(s->zero_bitmap, offset / s->granularity, 496 DIV_ROUND_UP(bytes, s->granularity)); 497 } 498 co = qemu_coroutine_create(mirror_co_discard, op); 499 break; 500 default: 501 abort(); 502 } 503 op->co = co; 504 505 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 506 qemu_coroutine_enter(co); 507 /* At this point, ownership of op has been moved to the coroutine 508 * and the object may already be freed */ 509 510 /* Assert that this value has been set */ 511 assert(bytes_handled >= 0); 512 513 /* Same assertion as in mirror_co_read() (and for mirror_co_read() 514 * and mirror_co_discard(), bytes_handled == op->bytes, which 515 * is the @bytes parameter given to this function) */ 516 assert(bytes_handled <= UINT_MAX); 517 return bytes_handled; 518 } 519 520 static void coroutine_fn GRAPH_UNLOCKED mirror_iteration(MirrorBlockJob *s) 521 { 522 BlockDriverState *source; 523 MirrorOp *pseudo_op; 524 int64_t offset; 525 /* At least the first dirty chunk is mirrored in one iteration. */ 526 int nb_chunks = 1; 527 bool write_zeroes_ok = bdrv_can_write_zeroes_with_unmap(blk_bs(s->target)); 528 int max_io_bytes = MAX(s->buf_size / MAX_IN_FLIGHT, MAX_IO_BYTES); 529 530 bdrv_graph_co_rdlock(); 531 source = s->mirror_top_bs->backing->bs; 532 bdrv_graph_co_rdunlock(); 533 534 bdrv_dirty_bitmap_lock(s->dirty_bitmap); 535 offset = bdrv_dirty_iter_next(s->dbi); 536 if (offset < 0) { 537 bdrv_set_dirty_iter(s->dbi, 0); 538 offset = bdrv_dirty_iter_next(s->dbi); 539 trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap)); 540 assert(offset >= 0); 541 } 542 bdrv_dirty_bitmap_unlock(s->dirty_bitmap); 543 544 /* 545 * Wait for concurrent requests to @offset. The next loop will limit the 546 * copied area based on in_flight_bitmap so we only copy an area that does 547 * not overlap with concurrent in-flight requests. Still, we would like to 548 * copy something, so wait until there are at least no more requests to the 549 * very beginning of the area. 550 */ 551 mirror_wait_on_conflicts(NULL, s, offset, 1); 552 553 job_pause_point(&s->common.job); 554 555 /* Find the number of consecutive dirty chunks following the first dirty 556 * one, and wait for in flight requests in them. */ 557 bdrv_dirty_bitmap_lock(s->dirty_bitmap); 558 while (nb_chunks * s->granularity < s->buf_size) { 559 int64_t next_dirty; 560 int64_t next_offset = offset + nb_chunks * s->granularity; 561 int64_t next_chunk = next_offset / s->granularity; 562 if (next_offset >= s->bdev_length || 563 !bdrv_dirty_bitmap_get_locked(s->dirty_bitmap, next_offset)) { 564 break; 565 } 566 if (test_bit(next_chunk, s->in_flight_bitmap)) { 567 break; 568 } 569 570 next_dirty = bdrv_dirty_iter_next(s->dbi); 571 if (next_dirty > next_offset || next_dirty < 0) { 572 /* The bitmap iterator's cache is stale, refresh it */ 573 bdrv_set_dirty_iter(s->dbi, next_offset); 574 next_dirty = bdrv_dirty_iter_next(s->dbi); 575 } 576 assert(next_dirty == next_offset); 577 nb_chunks++; 578 } 579 580 /* Clear dirty bits before querying the block status, because 581 * calling bdrv_block_status_above could yield - if some blocks are 582 * marked dirty in this window, we need to know. 583 */ 584 bdrv_reset_dirty_bitmap_locked(s->dirty_bitmap, offset, 585 nb_chunks * s->granularity); 586 bdrv_dirty_bitmap_unlock(s->dirty_bitmap); 587 588 /* Before claiming an area in the in-flight bitmap, we have to 589 * create a MirrorOp for it so that conflicting requests can wait 590 * for it. mirror_perform() will create the real MirrorOps later, 591 * for now we just create a pseudo operation that will wake up all 592 * conflicting requests once all real operations have been 593 * launched. */ 594 pseudo_op = g_new(MirrorOp, 1); 595 *pseudo_op = (MirrorOp){ 596 .offset = offset, 597 .bytes = nb_chunks * s->granularity, 598 .is_pseudo_op = true, 599 }; 600 qemu_co_queue_init(&pseudo_op->waiting_requests); 601 QTAILQ_INSERT_TAIL(&s->ops_in_flight, pseudo_op, next); 602 603 bitmap_set(s->in_flight_bitmap, offset / s->granularity, nb_chunks); 604 while (nb_chunks > 0 && offset < s->bdev_length) { 605 int ret = -1; 606 int64_t io_bytes; 607 int64_t io_bytes_acct; 608 bool io_skipped = false; 609 MirrorMethod mirror_method = MIRROR_METHOD_COPY; 610 611 assert(!(offset % s->granularity)); 612 WITH_GRAPH_RDLOCK_GUARD() { 613 ret = bdrv_co_block_status_above(source, NULL, offset, 614 nb_chunks * s->granularity, 615 &io_bytes, NULL, NULL); 616 } 617 if (ret < 0) { 618 io_bytes = MIN(nb_chunks * s->granularity, max_io_bytes); 619 } else if (ret & BDRV_BLOCK_DATA) { 620 io_bytes = MIN(io_bytes, max_io_bytes); 621 } 622 623 io_bytes -= io_bytes % s->granularity; 624 if (io_bytes < s->granularity) { 625 io_bytes = s->granularity; 626 } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) { 627 int64_t target_offset; 628 int64_t target_bytes; 629 WITH_GRAPH_RDLOCK_GUARD() { 630 bdrv_round_to_subclusters(blk_bs(s->target), offset, io_bytes, 631 &target_offset, &target_bytes); 632 } 633 if (target_offset == offset && 634 target_bytes == io_bytes) { 635 mirror_method = ret & BDRV_BLOCK_ZERO ? 636 MIRROR_METHOD_ZERO : 637 MIRROR_METHOD_DISCARD; 638 } 639 } 640 641 while (s->in_flight >= MAX_IN_FLIGHT) { 642 trace_mirror_yield_in_flight(s, offset, s->in_flight); 643 mirror_wait_for_free_in_flight_slot(s); 644 } 645 646 if (s->ret < 0) { 647 ret = 0; 648 goto fail; 649 } 650 651 io_bytes = mirror_clip_bytes(s, offset, io_bytes); 652 io_bytes = mirror_perform(s, offset, io_bytes, mirror_method, 653 &io_skipped); 654 if (io_skipped || 655 (mirror_method != MIRROR_METHOD_COPY && write_zeroes_ok)) { 656 io_bytes_acct = 0; 657 } else { 658 io_bytes_acct = io_bytes; 659 } 660 assert(io_bytes); 661 offset += io_bytes; 662 nb_chunks -= DIV_ROUND_UP(io_bytes, s->granularity); 663 block_job_ratelimit_processed_bytes(&s->common, io_bytes_acct); 664 } 665 666 fail: 667 QTAILQ_REMOVE(&s->ops_in_flight, pseudo_op, next); 668 qemu_co_queue_restart_all(&pseudo_op->waiting_requests); 669 g_free(pseudo_op); 670 } 671 672 static void mirror_free_init(MirrorBlockJob *s) 673 { 674 int granularity = s->granularity; 675 size_t buf_size = s->buf_size; 676 uint8_t *buf = s->buf; 677 678 assert(s->buf_free_count == 0); 679 QSIMPLEQ_INIT(&s->buf_free); 680 while (buf_size != 0) { 681 MirrorBuffer *cur = (MirrorBuffer *)buf; 682 QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); 683 s->buf_free_count++; 684 buf_size -= granularity; 685 buf += granularity; 686 } 687 } 688 689 /* This is also used for the .pause callback. There is no matching 690 * mirror_resume() because mirror_run() will begin iterating again 691 * when the job is resumed. 692 */ 693 static void coroutine_fn mirror_wait_for_all_io(MirrorBlockJob *s) 694 { 695 while (s->in_flight > 0) { 696 mirror_wait_for_free_in_flight_slot(s); 697 } 698 } 699 700 /** 701 * mirror_exit_common: handle both abort() and prepare() cases. 702 * for .prepare, returns 0 on success and -errno on failure. 703 * for .abort cases, denoted by abort = true, MUST return 0. 704 */ 705 static int mirror_exit_common(Job *job) 706 { 707 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 708 BlockJob *bjob = &s->common; 709 MirrorBDSOpaque *bs_opaque; 710 BlockDriverState *src; 711 BlockDriverState *target_bs; 712 BlockDriverState *mirror_top_bs; 713 Error *local_err = NULL; 714 bool abort = job->ret < 0; 715 int ret = 0; 716 717 GLOBAL_STATE_CODE(); 718 719 if (s->prepared) { 720 return 0; 721 } 722 s->prepared = true; 723 724 bdrv_graph_rdlock_main_loop(); 725 726 mirror_top_bs = s->mirror_top_bs; 727 bs_opaque = mirror_top_bs->opaque; 728 src = mirror_top_bs->backing->bs; 729 target_bs = blk_bs(s->target); 730 731 if (bdrv_chain_contains(src, target_bs)) { 732 bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs); 733 } 734 735 bdrv_release_dirty_bitmap(s->dirty_bitmap); 736 737 /* Make sure that the source BDS doesn't go away during bdrv_replace_node, 738 * before we can call bdrv_drained_end */ 739 bdrv_ref(src); 740 bdrv_ref(mirror_top_bs); 741 bdrv_ref(target_bs); 742 743 bdrv_graph_rdunlock_main_loop(); 744 745 /* 746 * Remove target parent that still uses BLK_PERM_WRITE/RESIZE before 747 * inserting target_bs at s->to_replace, where we might not be able to get 748 * these permissions. 749 */ 750 blk_unref(s->target); 751 s->target = NULL; 752 753 /* We don't access the source any more. Dropping any WRITE/RESIZE is 754 * required before it could become a backing file of target_bs. Not having 755 * these permissions any more means that we can't allow any new requests on 756 * mirror_top_bs from now on, so keep it drained. */ 757 bdrv_drained_begin(mirror_top_bs); 758 bdrv_drained_begin(target_bs); 759 bs_opaque->stop = true; 760 761 bdrv_graph_rdlock_main_loop(); 762 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 763 &error_abort); 764 765 if (!abort && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { 766 BlockDriverState *backing; 767 BlockDriverState *unfiltered_target = bdrv_skip_filters(target_bs); 768 769 backing = s->sync_mode == MIRROR_SYNC_MODE_NONE ? src : s->base; 770 if (bdrv_cow_bs(unfiltered_target) != backing) { 771 bdrv_set_backing_hd(unfiltered_target, backing, &local_err); 772 if (local_err) { 773 error_report_err(local_err); 774 local_err = NULL; 775 ret = -EPERM; 776 } 777 } 778 } else if (!abort && s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { 779 assert(!bdrv_backing_chain_next(target_bs)); 780 ret = bdrv_open_backing_file(bdrv_skip_filters(target_bs), NULL, 781 "backing", &local_err); 782 if (ret < 0) { 783 error_report_err(local_err); 784 local_err = NULL; 785 } 786 } 787 bdrv_graph_rdunlock_main_loop(); 788 789 if (s->should_complete && !abort) { 790 BlockDriverState *to_replace = s->to_replace ?: src; 791 bool ro = bdrv_is_read_only(to_replace); 792 793 if (ro != bdrv_is_read_only(target_bs)) { 794 bdrv_reopen_set_read_only(target_bs, ro, NULL); 795 } 796 797 /* The mirror job has no requests in flight any more, but we need to 798 * drain potential other users of the BDS before changing the graph. */ 799 assert(s->in_drain); 800 bdrv_drained_begin(to_replace); 801 /* 802 * Cannot use check_to_replace_node() here, because that would 803 * check for an op blocker on @to_replace, and we have our own 804 * there. 805 */ 806 bdrv_graph_wrlock(); 807 if (bdrv_recurse_can_replace(src, to_replace)) { 808 bdrv_replace_node(to_replace, target_bs, &local_err); 809 } else { 810 error_setg(&local_err, "Can no longer replace '%s' by '%s', " 811 "because it can no longer be guaranteed that doing so " 812 "would not lead to an abrupt change of visible data", 813 to_replace->node_name, target_bs->node_name); 814 } 815 bdrv_graph_wrunlock(); 816 bdrv_drained_end(to_replace); 817 if (local_err) { 818 error_report_err(local_err); 819 ret = -EPERM; 820 } 821 } 822 if (s->to_replace) { 823 bdrv_op_unblock_all(s->to_replace, s->replace_blocker); 824 error_free(s->replace_blocker); 825 bdrv_unref(s->to_replace); 826 } 827 g_free(s->replaces); 828 829 /* 830 * Remove the mirror filter driver from the graph. Before this, get rid of 831 * the blockers on the intermediate nodes so that the resulting state is 832 * valid. 833 */ 834 block_job_remove_all_bdrv(bjob); 835 bdrv_graph_wrlock(); 836 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort); 837 bdrv_graph_wrunlock(); 838 839 if (abort && s->base_ro && !bdrv_is_read_only(target_bs)) { 840 bdrv_reopen_set_read_only(target_bs, true, NULL); 841 } 842 843 bdrv_drained_end(target_bs); 844 bdrv_unref(target_bs); 845 846 bs_opaque->job = NULL; 847 848 bdrv_drained_end(src); 849 bdrv_drained_end(mirror_top_bs); 850 s->in_drain = false; 851 bdrv_unref(mirror_top_bs); 852 bdrv_unref(src); 853 854 return ret; 855 } 856 857 static int mirror_prepare(Job *job) 858 { 859 return mirror_exit_common(job); 860 } 861 862 static void mirror_abort(Job *job) 863 { 864 int ret = mirror_exit_common(job); 865 assert(ret == 0); 866 } 867 868 static void coroutine_fn mirror_throttle(MirrorBlockJob *s) 869 { 870 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 871 872 if (now - s->last_pause_ns > BLOCK_JOB_SLICE_TIME) { 873 s->last_pause_ns = now; 874 job_sleep_ns(&s->common.job, 0); 875 } else { 876 job_pause_point(&s->common.job); 877 } 878 } 879 880 static int coroutine_fn GRAPH_UNLOCKED mirror_dirty_init(MirrorBlockJob *s) 881 { 882 int64_t offset; 883 BlockDriverState *bs; 884 BlockDriverState *target_bs = blk_bs(s->target); 885 int ret = -EIO; 886 int64_t count; 887 bool punch_holes = 888 target_bs->detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP && 889 bdrv_can_write_zeroes_with_unmap(target_bs); 890 int64_t bitmap_length = DIV_ROUND_UP(s->bdev_length, s->granularity); 891 892 /* Determine if the image is already zero, regardless of sync mode. */ 893 s->zero_bitmap = bitmap_new(bitmap_length); 894 bdrv_graph_co_rdlock(); 895 bs = s->mirror_top_bs->backing->bs; 896 if (s->target_is_zero) { 897 ret = 1; 898 } else { 899 ret = bdrv_co_is_all_zeroes(target_bs); 900 } 901 bdrv_graph_co_rdunlock(); 902 903 /* Determine if a pre-zeroing pass is necessary. */ 904 if (ret < 0) { 905 return ret; 906 } else if (s->sync_mode == MIRROR_SYNC_MODE_TOP) { 907 /* 908 * In TOP mode, there is no benefit to a pre-zeroing pass, but 909 * the zero bitmap can be set if the destination already reads 910 * as zero and we are not punching holes. 911 */ 912 if (ret > 0 && !punch_holes) { 913 bitmap_set(s->zero_bitmap, 0, bitmap_length); 914 } 915 } else if (ret == 0 || punch_holes) { 916 /* 917 * Here, we are in FULL mode; our goal is to avoid writing 918 * zeroes if the destination already reads as zero, except 919 * when we are trying to punch holes. This is possible if 920 * zeroing happened externally (ret > 0) or if we have a fast 921 * way to pre-zero the image (the dirty bitmap will be 922 * populated later by the non-zero portions, the same as for 923 * TOP mode). If pre-zeroing is not fast, or we need to visit 924 * the entire image in order to punch holes even in the 925 * non-allocated regions of the source, then just mark the 926 * entire image dirty and leave the zero bitmap clear at this 927 * point in time. Otherwise, it can be faster to pre-zero the 928 * image now, even if we re-write the allocated portions of 929 * the disk later, and the pre-zero pass will populate the 930 * zero bitmap. 931 */ 932 if (!bdrv_can_write_zeroes_with_unmap(target_bs) || punch_holes) { 933 bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length); 934 return 0; 935 } 936 937 s->initial_zeroing_ongoing = true; 938 for (offset = 0; offset < s->bdev_length; ) { 939 int bytes = MIN(s->bdev_length - offset, 940 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 941 bool ignored; 942 943 mirror_throttle(s); 944 945 if (job_is_cancelled(&s->common.job)) { 946 s->initial_zeroing_ongoing = false; 947 return 0; 948 } 949 950 if (s->in_flight >= MAX_IN_FLIGHT) { 951 trace_mirror_yield(s, UINT64_MAX, s->buf_free_count, 952 s->in_flight); 953 mirror_wait_for_free_in_flight_slot(s); 954 continue; 955 } 956 957 mirror_perform(s, offset, bytes, MIRROR_METHOD_ZERO, &ignored); 958 offset += bytes; 959 } 960 961 mirror_wait_for_all_io(s); 962 s->initial_zeroing_ongoing = false; 963 } else { 964 /* In FULL mode, and image already reads as zero. */ 965 bitmap_set(s->zero_bitmap, 0, bitmap_length); 966 } 967 968 /* First part, loop on the sectors and initialize the dirty bitmap. */ 969 for (offset = 0; offset < s->bdev_length; ) { 970 /* Just to make sure we are not exceeding int limit. */ 971 int bytes = MIN(s->bdev_length - offset, 972 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 973 974 mirror_throttle(s); 975 976 if (job_is_cancelled(&s->common.job)) { 977 return 0; 978 } 979 980 WITH_GRAPH_RDLOCK_GUARD() { 981 ret = bdrv_co_is_allocated_above(bs, s->base_overlay, true, offset, 982 bytes, &count); 983 } 984 if (ret < 0) { 985 return ret; 986 } 987 988 assert(count); 989 if (ret > 0) { 990 bdrv_set_dirty_bitmap(s->dirty_bitmap, offset, count); 991 } 992 offset += count; 993 } 994 return 0; 995 } 996 997 /* Called when going out of the streaming phase to flush the bulk of the 998 * data to the medium, or just before completing. 999 */ 1000 static int coroutine_fn mirror_flush(MirrorBlockJob *s) 1001 { 1002 int ret = blk_co_flush(s->target); 1003 if (ret < 0) { 1004 if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) { 1005 s->ret = ret; 1006 } 1007 } 1008 return ret; 1009 } 1010 1011 static int coroutine_fn mirror_run(Job *job, Error **errp) 1012 { 1013 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1014 BlockDriverState *bs; 1015 MirrorBDSOpaque *mirror_top_opaque = s->mirror_top_bs->opaque; 1016 BlockDriverState *target_bs = blk_bs(s->target); 1017 bool need_drain = true; 1018 BlockDeviceIoStatus iostatus = BLOCK_DEVICE_IO_STATUS__MAX; 1019 int64_t length; 1020 int64_t target_length; 1021 BlockDriverInfo bdi; 1022 char backing_filename[2]; /* we only need 2 characters because we are only 1023 checking for a NULL string */ 1024 int ret = 0; 1025 1026 bdrv_graph_co_rdlock(); 1027 bs = bdrv_filter_bs(s->mirror_top_bs); 1028 bdrv_graph_co_rdunlock(); 1029 1030 if (job_is_cancelled(&s->common.job)) { 1031 goto immediate_exit; 1032 } 1033 1034 bdrv_graph_co_rdlock(); 1035 s->bdev_length = bdrv_co_getlength(bs); 1036 bdrv_graph_co_rdunlock(); 1037 1038 if (s->bdev_length < 0) { 1039 ret = s->bdev_length; 1040 goto immediate_exit; 1041 } 1042 1043 target_length = blk_co_getlength(s->target); 1044 if (target_length < 0) { 1045 ret = target_length; 1046 goto immediate_exit; 1047 } 1048 1049 /* Active commit must resize the base image if its size differs from the 1050 * active layer. */ 1051 if (s->base == blk_bs(s->target)) { 1052 if (s->bdev_length > target_length) { 1053 ret = blk_co_truncate(s->target, s->bdev_length, false, 1054 PREALLOC_MODE_OFF, 0, NULL); 1055 if (ret < 0) { 1056 goto immediate_exit; 1057 } 1058 } 1059 } else if (s->bdev_length != target_length) { 1060 error_setg(errp, "Source and target image have different sizes"); 1061 ret = -EINVAL; 1062 goto immediate_exit; 1063 } 1064 1065 if (s->bdev_length == 0) { 1066 /* Transition to the READY state and wait for complete. */ 1067 job_transition_to_ready(&s->common.job); 1068 qatomic_set(&s->actively_synced, true); 1069 while (!job_cancel_requested(&s->common.job) && !s->should_complete) { 1070 job_yield(&s->common.job); 1071 } 1072 goto immediate_exit; 1073 } 1074 1075 length = DIV_ROUND_UP(s->bdev_length, s->granularity); 1076 s->in_flight_bitmap = bitmap_new(length); 1077 1078 /* If we have no backing file yet in the destination, we cannot let 1079 * the destination do COW. Instead, we copy sectors around the 1080 * dirty data if needed. We need a bitmap to do that. 1081 */ 1082 bdrv_get_backing_filename(target_bs, backing_filename, 1083 sizeof(backing_filename)); 1084 bdrv_graph_co_rdlock(); 1085 if (!bdrv_co_get_info(target_bs, &bdi) && bdi.cluster_size) { 1086 s->target_cluster_size = bdi.cluster_size; 1087 } else { 1088 s->target_cluster_size = BDRV_SECTOR_SIZE; 1089 } 1090 if (backing_filename[0] && !bdrv_backing_chain_next(target_bs) && 1091 s->granularity < s->target_cluster_size) { 1092 s->buf_size = MAX(s->buf_size, s->target_cluster_size); 1093 s->cow_bitmap = bitmap_new(length); 1094 } 1095 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); 1096 bdrv_graph_co_rdunlock(); 1097 1098 s->buf = qemu_try_blockalign(bs, s->buf_size); 1099 if (s->buf == NULL) { 1100 ret = -ENOMEM; 1101 goto immediate_exit; 1102 } 1103 1104 mirror_free_init(s); 1105 1106 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 1107 if (s->sync_mode != MIRROR_SYNC_MODE_NONE) { 1108 ret = mirror_dirty_init(s); 1109 if (ret < 0 || job_is_cancelled(&s->common.job)) { 1110 goto immediate_exit; 1111 } 1112 } 1113 1114 /* 1115 * Only now the job is fully initialised and mirror_top_bs should start 1116 * accessing it. 1117 */ 1118 mirror_top_opaque->job = s; 1119 1120 assert(!s->dbi); 1121 s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap); 1122 for (;;) { 1123 int64_t cnt, delta; 1124 bool should_complete; 1125 1126 if (s->ret < 0) { 1127 ret = s->ret; 1128 goto immediate_exit; 1129 } 1130 1131 job_pause_point(&s->common.job); 1132 1133 if (job_is_cancelled(&s->common.job)) { 1134 ret = 0; 1135 goto immediate_exit; 1136 } 1137 1138 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1139 /* cnt is the number of dirty bytes remaining and s->bytes_in_flight is 1140 * the number of bytes currently being processed; together those are 1141 * the current remaining operation length */ 1142 job_progress_set_remaining(&s->common.job, 1143 s->bytes_in_flight + cnt + 1144 s->active_write_bytes_in_flight); 1145 1146 /* Note that even when no rate limit is applied we need to yield 1147 * periodically with no pending I/O so that bdrv_drain_all() returns. 1148 * We do so every BLKOCK_JOB_SLICE_TIME nanoseconds, or when there is 1149 * an error, or when the source is clean, whichever comes first. */ 1150 delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns; 1151 WITH_JOB_LOCK_GUARD() { 1152 iostatus = s->common.iostatus; 1153 } 1154 if (delta < BLOCK_JOB_SLICE_TIME && 1155 iostatus == BLOCK_DEVICE_IO_STATUS_OK) { 1156 if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || 1157 (cnt == 0 && s->in_flight > 0)) { 1158 trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight); 1159 mirror_wait_for_free_in_flight_slot(s); 1160 continue; 1161 } else if (cnt != 0) { 1162 mirror_iteration(s); 1163 } 1164 } 1165 1166 should_complete = false; 1167 if (s->in_flight == 0 && cnt == 0) { 1168 trace_mirror_before_flush(s); 1169 if (!job_is_ready(&s->common.job)) { 1170 if (mirror_flush(s) < 0) { 1171 /* Go check s->ret. */ 1172 continue; 1173 } 1174 /* We're out of the streaming phase. From now on, if the job 1175 * is cancelled we will actually complete all pending I/O and 1176 * report completion. This way, block-job-cancel will leave 1177 * the target in a consistent state. 1178 */ 1179 job_transition_to_ready(&s->common.job); 1180 } 1181 if (qatomic_read(&s->copy_mode) != MIRROR_COPY_MODE_BACKGROUND) { 1182 qatomic_set(&s->actively_synced, true); 1183 } 1184 1185 should_complete = s->should_complete || 1186 job_cancel_requested(&s->common.job); 1187 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1188 } 1189 1190 if (cnt == 0 && should_complete) { 1191 /* The dirty bitmap is not updated while operations are pending. 1192 * If we're about to exit, wait for pending operations before 1193 * calling bdrv_get_dirty_count(bs), or we may exit while the 1194 * source has dirty data to copy! 1195 * 1196 * Note that I/O can be submitted by the guest while 1197 * mirror_populate runs, so pause it now. Before deciding 1198 * whether to switch to target check one last time if I/O has 1199 * come in the meanwhile, and if not flush the data to disk. 1200 */ 1201 trace_mirror_before_drain(s, cnt); 1202 1203 s->in_drain = true; 1204 bdrv_drained_begin(bs); 1205 1206 /* Must be zero because we are drained */ 1207 assert(s->in_active_write_counter == 0); 1208 1209 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1210 if (cnt > 0 || mirror_flush(s) < 0) { 1211 bdrv_drained_end(bs); 1212 s->in_drain = false; 1213 continue; 1214 } 1215 1216 /* The two disks are in sync. Exit and report successful 1217 * completion. 1218 */ 1219 assert(QLIST_EMPTY(&bs->tracked_requests)); 1220 need_drain = false; 1221 break; 1222 } 1223 1224 if (job_is_ready(&s->common.job) && !should_complete) { 1225 if (s->in_flight == 0 && cnt == 0) { 1226 trace_mirror_before_sleep(s, cnt, job_is_ready(&s->common.job), 1227 BLOCK_JOB_SLICE_TIME); 1228 job_sleep_ns(&s->common.job, BLOCK_JOB_SLICE_TIME); 1229 } 1230 } else { 1231 block_job_ratelimit_sleep(&s->common); 1232 } 1233 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 1234 } 1235 1236 immediate_exit: 1237 if (s->in_flight > 0) { 1238 /* We get here only if something went wrong. Either the job failed, 1239 * or it was cancelled prematurely so that we do not guarantee that 1240 * the target is a copy of the source. 1241 */ 1242 assert(ret < 0 || job_is_cancelled(&s->common.job)); 1243 assert(need_drain); 1244 mirror_wait_for_all_io(s); 1245 } 1246 1247 assert(s->in_flight == 0); 1248 qemu_vfree(s->buf); 1249 g_free(s->cow_bitmap); 1250 g_free(s->zero_bitmap); 1251 g_free(s->in_flight_bitmap); 1252 bdrv_dirty_iter_free(s->dbi); 1253 1254 if (need_drain) { 1255 s->in_drain = true; 1256 bdrv_drained_begin(bs); 1257 } 1258 1259 return ret; 1260 } 1261 1262 static void mirror_complete(Job *job, Error **errp) 1263 { 1264 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1265 1266 if (!job_is_ready(job)) { 1267 error_setg(errp, "The active block job '%s' cannot be completed", 1268 job->id); 1269 return; 1270 } 1271 1272 /* block all operations on to_replace bs */ 1273 if (s->replaces) { 1274 s->to_replace = bdrv_find_node(s->replaces); 1275 if (!s->to_replace) { 1276 error_setg(errp, "Node name '%s' not found", s->replaces); 1277 return; 1278 } 1279 1280 /* TODO Translate this into child freeze system. */ 1281 error_setg(&s->replace_blocker, 1282 "block device is in use by block-job-complete"); 1283 bdrv_op_block_all(s->to_replace, s->replace_blocker); 1284 bdrv_ref(s->to_replace); 1285 } 1286 1287 s->should_complete = true; 1288 1289 /* If the job is paused, it will be re-entered when it is resumed */ 1290 WITH_JOB_LOCK_GUARD() { 1291 if (!job->paused) { 1292 job_enter_cond_locked(job, NULL); 1293 } 1294 } 1295 } 1296 1297 static void coroutine_fn mirror_pause(Job *job) 1298 { 1299 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1300 1301 mirror_wait_for_all_io(s); 1302 } 1303 1304 static bool mirror_drained_poll(BlockJob *job) 1305 { 1306 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1307 1308 /* If the job isn't paused nor cancelled, we can't be sure that it won't 1309 * issue more requests. We make an exception if we've reached this point 1310 * from one of our own drain sections, to avoid a deadlock waiting for 1311 * ourselves. 1312 */ 1313 WITH_JOB_LOCK_GUARD() { 1314 if (!s->common.job.paused && !job_is_cancelled_locked(&job->job) 1315 && !s->in_drain) { 1316 return true; 1317 } 1318 } 1319 1320 return !!s->in_flight; 1321 } 1322 1323 static bool mirror_cancel(Job *job, bool force) 1324 { 1325 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1326 BlockDriverState *target = blk_bs(s->target); 1327 1328 /* 1329 * Before the job is READY, we treat any cancellation like a 1330 * force-cancellation. 1331 */ 1332 force = force || !job_is_ready(job); 1333 1334 if (force) { 1335 bdrv_cancel_in_flight(target); 1336 } 1337 return force; 1338 } 1339 1340 static bool commit_active_cancel(Job *job, bool force) 1341 { 1342 /* Same as above in mirror_cancel() */ 1343 return force || !job_is_ready(job); 1344 } 1345 1346 static void mirror_change(BlockJob *job, BlockJobChangeOptions *opts, 1347 Error **errp) 1348 { 1349 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1350 BlockJobChangeOptionsMirror *change_opts = &opts->u.mirror; 1351 MirrorCopyMode current; 1352 1353 /* 1354 * The implementation relies on the fact that copy_mode is only written 1355 * under the BQL. Otherwise, further synchronization would be required. 1356 */ 1357 1358 GLOBAL_STATE_CODE(); 1359 1360 if (qatomic_read(&s->copy_mode) == change_opts->copy_mode) { 1361 return; 1362 } 1363 1364 if (change_opts->copy_mode != MIRROR_COPY_MODE_WRITE_BLOCKING) { 1365 error_setg(errp, "Change to copy mode '%s' is not implemented", 1366 MirrorCopyMode_str(change_opts->copy_mode)); 1367 return; 1368 } 1369 1370 current = qatomic_cmpxchg(&s->copy_mode, MIRROR_COPY_MODE_BACKGROUND, 1371 change_opts->copy_mode); 1372 if (current != MIRROR_COPY_MODE_BACKGROUND) { 1373 error_setg(errp, "Expected current copy mode '%s', got '%s'", 1374 MirrorCopyMode_str(MIRROR_COPY_MODE_BACKGROUND), 1375 MirrorCopyMode_str(current)); 1376 } 1377 } 1378 1379 static void mirror_query(BlockJob *job, BlockJobInfo *info) 1380 { 1381 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1382 1383 info->u.mirror = (BlockJobInfoMirror) { 1384 .actively_synced = qatomic_read(&s->actively_synced), 1385 }; 1386 } 1387 1388 static const BlockJobDriver mirror_job_driver = { 1389 .job_driver = { 1390 .instance_size = sizeof(MirrorBlockJob), 1391 .job_type = JOB_TYPE_MIRROR, 1392 .free = block_job_free, 1393 .user_resume = block_job_user_resume, 1394 .run = mirror_run, 1395 .prepare = mirror_prepare, 1396 .abort = mirror_abort, 1397 .pause = mirror_pause, 1398 .complete = mirror_complete, 1399 .cancel = mirror_cancel, 1400 }, 1401 .drained_poll = mirror_drained_poll, 1402 .change = mirror_change, 1403 .query = mirror_query, 1404 }; 1405 1406 static const BlockJobDriver commit_active_job_driver = { 1407 .job_driver = { 1408 .instance_size = sizeof(MirrorBlockJob), 1409 .job_type = JOB_TYPE_COMMIT, 1410 .free = block_job_free, 1411 .user_resume = block_job_user_resume, 1412 .run = mirror_run, 1413 .prepare = mirror_prepare, 1414 .abort = mirror_abort, 1415 .pause = mirror_pause, 1416 .complete = mirror_complete, 1417 .cancel = commit_active_cancel, 1418 }, 1419 .drained_poll = mirror_drained_poll, 1420 }; 1421 1422 static void coroutine_fn 1423 do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, 1424 uint64_t offset, uint64_t bytes, 1425 QEMUIOVector *qiov, int flags) 1426 { 1427 int ret; 1428 size_t qiov_offset = 0; 1429 int64_t dirty_bitmap_offset, dirty_bitmap_end; 1430 int64_t zero_bitmap_offset, zero_bitmap_end; 1431 1432 if (!QEMU_IS_ALIGNED(offset, job->granularity) && 1433 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset)) 1434 { 1435 /* 1436 * Dirty unaligned padding: ignore it. 1437 * 1438 * Reasoning: 1439 * 1. If we copy it, we can't reset corresponding bit in 1440 * dirty_bitmap as there may be some "dirty" bytes still not 1441 * copied. 1442 * 2. It's already dirty, so skipping it we don't diverge mirror 1443 * progress. 1444 * 1445 * Note, that because of this, guest write may have no contribution 1446 * into mirror converge, but that's not bad, as we have background 1447 * process of mirroring. If under some bad circumstances (high guest 1448 * IO load) background process starve, we will not converge anyway, 1449 * even if each write will contribute, as guest is not guaranteed to 1450 * rewrite the whole disk. 1451 */ 1452 qiov_offset = QEMU_ALIGN_UP(offset, job->granularity) - offset; 1453 if (bytes <= qiov_offset) { 1454 /* nothing to do after shrink */ 1455 return; 1456 } 1457 offset += qiov_offset; 1458 bytes -= qiov_offset; 1459 } 1460 1461 if (!QEMU_IS_ALIGNED(offset + bytes, job->granularity) && 1462 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset + bytes - 1)) 1463 { 1464 uint64_t tail = (offset + bytes) % job->granularity; 1465 1466 if (bytes <= tail) { 1467 /* nothing to do after shrink */ 1468 return; 1469 } 1470 bytes -= tail; 1471 } 1472 1473 /* 1474 * Tails are either clean or shrunk, so for dirty bitmap resetting 1475 * we safely align the range narrower. But for zero bitmap, round 1476 * range wider for checking or clearing, and narrower for setting. 1477 */ 1478 dirty_bitmap_offset = QEMU_ALIGN_UP(offset, job->granularity); 1479 dirty_bitmap_end = QEMU_ALIGN_DOWN(offset + bytes, job->granularity); 1480 if (dirty_bitmap_offset < dirty_bitmap_end) { 1481 bdrv_reset_dirty_bitmap(job->dirty_bitmap, dirty_bitmap_offset, 1482 dirty_bitmap_end - dirty_bitmap_offset); 1483 } 1484 zero_bitmap_offset = offset / job->granularity; 1485 zero_bitmap_end = DIV_ROUND_UP(offset + bytes, job->granularity); 1486 1487 job_progress_increase_remaining(&job->common.job, bytes); 1488 job->active_write_bytes_in_flight += bytes; 1489 1490 switch (method) { 1491 case MIRROR_METHOD_COPY: 1492 if (job->zero_bitmap) { 1493 bitmap_clear(job->zero_bitmap, zero_bitmap_offset, 1494 zero_bitmap_end - zero_bitmap_offset); 1495 } 1496 ret = blk_co_pwritev_part(job->target, offset, bytes, 1497 qiov, qiov_offset, flags); 1498 break; 1499 1500 case MIRROR_METHOD_ZERO: 1501 if (job->zero_bitmap) { 1502 if (find_next_zero_bit(job->zero_bitmap, zero_bitmap_end, 1503 zero_bitmap_offset) == zero_bitmap_end) { 1504 ret = 0; 1505 break; 1506 } 1507 } 1508 assert(!qiov); 1509 ret = blk_co_pwrite_zeroes(job->target, offset, bytes, flags); 1510 if (job->zero_bitmap && ret >= 0) { 1511 bitmap_set(job->zero_bitmap, dirty_bitmap_offset / job->granularity, 1512 (dirty_bitmap_end - dirty_bitmap_offset) / 1513 job->granularity); 1514 } 1515 break; 1516 1517 case MIRROR_METHOD_DISCARD: 1518 if (job->zero_bitmap) { 1519 bitmap_clear(job->zero_bitmap, zero_bitmap_offset, 1520 zero_bitmap_end - zero_bitmap_offset); 1521 } 1522 assert(!qiov); 1523 ret = blk_co_pdiscard(job->target, offset, bytes); 1524 break; 1525 1526 default: 1527 abort(); 1528 } 1529 1530 job->active_write_bytes_in_flight -= bytes; 1531 if (ret >= 0) { 1532 job_progress_update(&job->common.job, bytes); 1533 } else { 1534 BlockErrorAction action; 1535 1536 /* 1537 * We failed, so we should mark dirty the whole area, aligned up. 1538 * Note that we don't care about shrunk tails if any: they were dirty 1539 * at function start, and they must be still dirty, as we've locked 1540 * the region for in-flight op. 1541 */ 1542 dirty_bitmap_offset = QEMU_ALIGN_DOWN(offset, job->granularity); 1543 dirty_bitmap_end = QEMU_ALIGN_UP(offset + bytes, job->granularity); 1544 bdrv_set_dirty_bitmap(job->dirty_bitmap, dirty_bitmap_offset, 1545 dirty_bitmap_end - dirty_bitmap_offset); 1546 qatomic_set(&job->actively_synced, false); 1547 1548 action = mirror_error_action(job, false, -ret); 1549 if (action == BLOCK_ERROR_ACTION_REPORT) { 1550 if (!job->ret) { 1551 job->ret = ret; 1552 } 1553 } 1554 } 1555 } 1556 1557 static MirrorOp *coroutine_fn active_write_prepare(MirrorBlockJob *s, 1558 uint64_t offset, 1559 uint64_t bytes) 1560 { 1561 MirrorOp *op; 1562 uint64_t start_chunk = offset / s->granularity; 1563 uint64_t end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 1564 1565 op = g_new(MirrorOp, 1); 1566 *op = (MirrorOp){ 1567 .s = s, 1568 .offset = offset, 1569 .bytes = bytes, 1570 .is_active_write = true, 1571 .is_in_flight = true, 1572 .co = qemu_coroutine_self(), 1573 }; 1574 qemu_co_queue_init(&op->waiting_requests); 1575 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 1576 1577 s->in_active_write_counter++; 1578 1579 /* 1580 * Wait for concurrent requests affecting the area. If there are already 1581 * running requests that are copying off now-to-be stale data in the area, 1582 * we must wait for them to finish before we begin writing fresh data to the 1583 * target so that the write operations appear in the correct order. 1584 * Note that background requests (see mirror_iteration()) in contrast only 1585 * wait for conflicting requests at the start of the dirty area, and then 1586 * (based on the in_flight_bitmap) truncate the area to copy so it will not 1587 * conflict with any requests beyond that. For active writes, however, we 1588 * cannot truncate that area. The request from our parent must be blocked 1589 * until the area is copied in full. Therefore, we must wait for the whole 1590 * area to become free of concurrent requests. 1591 */ 1592 mirror_wait_on_conflicts(op, s, offset, bytes); 1593 1594 bitmap_set(s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1595 1596 return op; 1597 } 1598 1599 static void coroutine_fn GRAPH_RDLOCK active_write_settle(MirrorOp *op) 1600 { 1601 uint64_t start_chunk = op->offset / op->s->granularity; 1602 uint64_t end_chunk = DIV_ROUND_UP(op->offset + op->bytes, 1603 op->s->granularity); 1604 1605 if (!--op->s->in_active_write_counter && 1606 qatomic_read(&op->s->actively_synced)) { 1607 BdrvChild *source = op->s->mirror_top_bs->backing; 1608 1609 if (QLIST_FIRST(&source->bs->parents) == source && 1610 QLIST_NEXT(source, next_parent) == NULL) 1611 { 1612 /* Assert that we are back in sync once all active write 1613 * operations are settled. 1614 * Note that we can only assert this if the mirror node 1615 * is the source node's only parent. */ 1616 assert(!bdrv_get_dirty_count(op->s->dirty_bitmap)); 1617 } 1618 } 1619 bitmap_clear(op->s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1620 QTAILQ_REMOVE(&op->s->ops_in_flight, op, next); 1621 qemu_co_queue_restart_all(&op->waiting_requests); 1622 g_free(op); 1623 } 1624 1625 static int coroutine_fn GRAPH_RDLOCK 1626 bdrv_mirror_top_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes, 1627 QEMUIOVector *qiov, BdrvRequestFlags flags) 1628 { 1629 return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); 1630 } 1631 1632 static bool should_copy_to_target(MirrorBDSOpaque *s) 1633 { 1634 return s->job && s->job->ret >= 0 && 1635 !job_is_cancelled(&s->job->common.job) && 1636 qatomic_read(&s->job->copy_mode) == MIRROR_COPY_MODE_WRITE_BLOCKING; 1637 } 1638 1639 static int coroutine_fn GRAPH_RDLOCK 1640 bdrv_mirror_top_do_write(BlockDriverState *bs, MirrorMethod method, 1641 bool copy_to_target, uint64_t offset, uint64_t bytes, 1642 QEMUIOVector *qiov, int flags) 1643 { 1644 MirrorOp *op = NULL; 1645 MirrorBDSOpaque *s = bs->opaque; 1646 int ret = 0; 1647 1648 if (copy_to_target) { 1649 op = active_write_prepare(s->job, offset, bytes); 1650 } 1651 1652 switch (method) { 1653 case MIRROR_METHOD_COPY: 1654 ret = bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags); 1655 break; 1656 1657 case MIRROR_METHOD_ZERO: 1658 ret = bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags); 1659 break; 1660 1661 case MIRROR_METHOD_DISCARD: 1662 ret = bdrv_co_pdiscard(bs->backing, offset, bytes); 1663 break; 1664 1665 default: 1666 abort(); 1667 } 1668 1669 if (!copy_to_target && s->job && s->job->dirty_bitmap) { 1670 qatomic_set(&s->job->actively_synced, false); 1671 bdrv_set_dirty_bitmap(s->job->dirty_bitmap, offset, bytes); 1672 } 1673 1674 if (ret < 0) { 1675 goto out; 1676 } 1677 1678 if (copy_to_target) { 1679 do_sync_target_write(s->job, method, offset, bytes, qiov, flags); 1680 } 1681 1682 out: 1683 if (copy_to_target) { 1684 active_write_settle(op); 1685 } 1686 return ret; 1687 } 1688 1689 static int coroutine_fn GRAPH_RDLOCK 1690 bdrv_mirror_top_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes, 1691 QEMUIOVector *qiov, BdrvRequestFlags flags) 1692 { 1693 QEMUIOVector bounce_qiov; 1694 void *bounce_buf; 1695 int ret = 0; 1696 bool copy_to_target = should_copy_to_target(bs->opaque); 1697 1698 if (copy_to_target) { 1699 /* The guest might concurrently modify the data to write; but 1700 * the data on source and destination must match, so we have 1701 * to use a bounce buffer if we are going to write to the 1702 * target now. */ 1703 bounce_buf = qemu_blockalign(bs, bytes); 1704 iov_to_buf_full(qiov->iov, qiov->niov, 0, bounce_buf, bytes); 1705 1706 qemu_iovec_init(&bounce_qiov, 1); 1707 qemu_iovec_add(&bounce_qiov, bounce_buf, bytes); 1708 qiov = &bounce_qiov; 1709 1710 flags &= ~BDRV_REQ_REGISTERED_BUF; 1711 } 1712 1713 ret = bdrv_mirror_top_do_write(bs, MIRROR_METHOD_COPY, copy_to_target, 1714 offset, bytes, qiov, flags); 1715 1716 if (copy_to_target) { 1717 qemu_iovec_destroy(&bounce_qiov); 1718 qemu_vfree(bounce_buf); 1719 } 1720 1721 return ret; 1722 } 1723 1724 static int coroutine_fn GRAPH_RDLOCK bdrv_mirror_top_flush(BlockDriverState *bs) 1725 { 1726 if (bs->backing == NULL) { 1727 /* we can be here after failed bdrv_append in mirror_start_job */ 1728 return 0; 1729 } 1730 return bdrv_co_flush(bs->backing->bs); 1731 } 1732 1733 static int coroutine_fn GRAPH_RDLOCK 1734 bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs, int64_t offset, 1735 int64_t bytes, BdrvRequestFlags flags) 1736 { 1737 bool copy_to_target = should_copy_to_target(bs->opaque); 1738 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_ZERO, copy_to_target, 1739 offset, bytes, NULL, flags); 1740 } 1741 1742 static int coroutine_fn GRAPH_RDLOCK 1743 bdrv_mirror_top_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes) 1744 { 1745 bool copy_to_target = should_copy_to_target(bs->opaque); 1746 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_DISCARD, copy_to_target, 1747 offset, bytes, NULL, 0); 1748 } 1749 1750 static void GRAPH_RDLOCK bdrv_mirror_top_refresh_filename(BlockDriverState *bs) 1751 { 1752 if (bs->backing == NULL) { 1753 /* we can be here after failed bdrv_attach_child in 1754 * bdrv_set_backing_hd */ 1755 return; 1756 } 1757 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), 1758 bs->backing->bs->filename); 1759 } 1760 1761 static void bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c, 1762 BdrvChildRole role, 1763 BlockReopenQueue *reopen_queue, 1764 uint64_t perm, uint64_t shared, 1765 uint64_t *nperm, uint64_t *nshared) 1766 { 1767 MirrorBDSOpaque *s = bs->opaque; 1768 1769 if (s->stop) { 1770 /* 1771 * If the job is to be stopped, we do not need to forward 1772 * anything to the real image. 1773 */ 1774 *nperm = 0; 1775 *nshared = BLK_PERM_ALL; 1776 return; 1777 } 1778 1779 bdrv_default_perms(bs, c, role, reopen_queue, 1780 perm, shared, nperm, nshared); 1781 1782 if (s->is_commit) { 1783 /* 1784 * For commit jobs, we cannot take CONSISTENT_READ, because 1785 * that permission is unshared for everything above the base 1786 * node (except for filters on the base node). 1787 * We also have to force-share the WRITE permission, or 1788 * otherwise we would block ourselves at the base node (if 1789 * writes are blocked for a node, they are also blocked for 1790 * its backing file). 1791 * (We could also share RESIZE, because it may be needed for 1792 * the target if its size is less than the top node's; but 1793 * bdrv_default_perms_for_cow() automatically shares RESIZE 1794 * for backing nodes if WRITE is shared, so there is no need 1795 * to do it here.) 1796 */ 1797 *nperm &= ~BLK_PERM_CONSISTENT_READ; 1798 *nshared |= BLK_PERM_WRITE; 1799 } 1800 } 1801 1802 /* Dummy node that provides consistent read to its users without requiring it 1803 * from its backing file and that allows writes on the backing file chain. */ 1804 static BlockDriver bdrv_mirror_top = { 1805 .format_name = "mirror_top", 1806 .bdrv_co_preadv = bdrv_mirror_top_preadv, 1807 .bdrv_co_pwritev = bdrv_mirror_top_pwritev, 1808 .bdrv_co_pwrite_zeroes = bdrv_mirror_top_pwrite_zeroes, 1809 .bdrv_co_pdiscard = bdrv_mirror_top_pdiscard, 1810 .bdrv_co_flush = bdrv_mirror_top_flush, 1811 .bdrv_refresh_filename = bdrv_mirror_top_refresh_filename, 1812 .bdrv_child_perm = bdrv_mirror_top_child_perm, 1813 1814 .is_filter = true, 1815 .filtered_child_is_backing = true, 1816 }; 1817 1818 static BlockJob *mirror_start_job( 1819 const char *job_id, BlockDriverState *bs, 1820 int creation_flags, BlockDriverState *target, 1821 const char *replaces, int64_t speed, 1822 uint32_t granularity, int64_t buf_size, 1823 MirrorSyncMode sync_mode, 1824 BlockMirrorBackingMode backing_mode, 1825 bool target_is_zero, 1826 BlockdevOnError on_source_error, 1827 BlockdevOnError on_target_error, 1828 bool unmap, 1829 BlockCompletionFunc *cb, 1830 void *opaque, 1831 const BlockJobDriver *driver, 1832 BlockDriverState *base, 1833 bool auto_complete, const char *filter_node_name, 1834 bool is_mirror, MirrorCopyMode copy_mode, 1835 bool base_ro, 1836 Error **errp) 1837 { 1838 MirrorBlockJob *s; 1839 MirrorBDSOpaque *bs_opaque; 1840 BlockDriverState *mirror_top_bs; 1841 bool target_is_backing; 1842 uint64_t target_perms, target_shared_perms; 1843 int ret; 1844 1845 GLOBAL_STATE_CODE(); 1846 1847 if (granularity == 0) { 1848 granularity = bdrv_get_default_bitmap_granularity(target); 1849 } 1850 1851 assert(is_power_of_2(granularity)); 1852 1853 if (buf_size < 0) { 1854 error_setg(errp, "Invalid parameter 'buf-size'"); 1855 return NULL; 1856 } 1857 1858 if (buf_size == 0) { 1859 buf_size = DEFAULT_MIRROR_BUF_SIZE; 1860 } 1861 1862 bdrv_graph_rdlock_main_loop(); 1863 if (bdrv_skip_filters(bs) == bdrv_skip_filters(target)) { 1864 error_setg(errp, "Can't mirror node into itself"); 1865 bdrv_graph_rdunlock_main_loop(); 1866 return NULL; 1867 } 1868 1869 target_is_backing = bdrv_chain_contains(bs, target); 1870 bdrv_graph_rdunlock_main_loop(); 1871 1872 /* In the case of active commit, add dummy driver to provide consistent 1873 * reads on the top, while disabling it in the intermediate nodes, and make 1874 * the backing chain writable. */ 1875 mirror_top_bs = bdrv_new_open_driver(&bdrv_mirror_top, filter_node_name, 1876 BDRV_O_RDWR, errp); 1877 if (mirror_top_bs == NULL) { 1878 return NULL; 1879 } 1880 if (!filter_node_name) { 1881 mirror_top_bs->implicit = true; 1882 } 1883 1884 /* So that we can always drop this node */ 1885 mirror_top_bs->never_freeze = true; 1886 1887 mirror_top_bs->total_sectors = bs->total_sectors; 1888 mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED; 1889 mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED | 1890 BDRV_REQ_NO_FALLBACK; 1891 bs_opaque = g_new0(MirrorBDSOpaque, 1); 1892 mirror_top_bs->opaque = bs_opaque; 1893 1894 bs_opaque->is_commit = target_is_backing; 1895 1896 bdrv_drained_begin(bs); 1897 ret = bdrv_append(mirror_top_bs, bs, errp); 1898 bdrv_drained_end(bs); 1899 1900 if (ret < 0) { 1901 bdrv_unref(mirror_top_bs); 1902 return NULL; 1903 } 1904 1905 /* Make sure that the source is not resized while the job is running */ 1906 s = block_job_create(job_id, driver, NULL, mirror_top_bs, 1907 BLK_PERM_CONSISTENT_READ, 1908 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | 1909 BLK_PERM_WRITE, speed, 1910 creation_flags, cb, opaque, errp); 1911 if (!s) { 1912 goto fail; 1913 } 1914 1915 /* The block job now has a reference to this node */ 1916 bdrv_unref(mirror_top_bs); 1917 1918 s->mirror_top_bs = mirror_top_bs; 1919 s->base_ro = base_ro; 1920 1921 /* No resize for the target either; while the mirror is still running, a 1922 * consistent read isn't necessarily possible. We could possibly allow 1923 * writes and graph modifications, though it would likely defeat the 1924 * purpose of a mirror, so leave them blocked for now. 1925 * 1926 * In the case of active commit, things look a bit different, though, 1927 * because the target is an already populated backing file in active use. 1928 * We can allow anything except resize there.*/ 1929 1930 target_perms = BLK_PERM_WRITE; 1931 target_shared_perms = BLK_PERM_WRITE_UNCHANGED; 1932 1933 if (target_is_backing) { 1934 int64_t bs_size, target_size; 1935 bs_size = bdrv_getlength(bs); 1936 if (bs_size < 0) { 1937 error_setg_errno(errp, -bs_size, 1938 "Could not inquire top image size"); 1939 goto fail; 1940 } 1941 1942 target_size = bdrv_getlength(target); 1943 if (target_size < 0) { 1944 error_setg_errno(errp, -target_size, 1945 "Could not inquire base image size"); 1946 goto fail; 1947 } 1948 1949 if (target_size < bs_size) { 1950 target_perms |= BLK_PERM_RESIZE; 1951 } 1952 1953 target_shared_perms |= BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE; 1954 } else { 1955 bdrv_graph_rdlock_main_loop(); 1956 if (bdrv_chain_contains(bs, bdrv_skip_filters(target))) { 1957 /* 1958 * We may want to allow this in the future, but it would 1959 * require taking some extra care. 1960 */ 1961 error_setg(errp, "Cannot mirror to a filter on top of a node in " 1962 "the source's backing chain"); 1963 bdrv_graph_rdunlock_main_loop(); 1964 goto fail; 1965 } 1966 bdrv_graph_rdunlock_main_loop(); 1967 } 1968 1969 s->target = blk_new(s->common.job.aio_context, 1970 target_perms, target_shared_perms); 1971 ret = blk_insert_bs(s->target, target, errp); 1972 if (ret < 0) { 1973 goto fail; 1974 } 1975 if (is_mirror) { 1976 /* XXX: Mirror target could be a NBD server of target QEMU in the case 1977 * of non-shared block migration. To allow migration completion, we 1978 * have to allow "inactivate" of the target BB. When that happens, we 1979 * know the job is drained, and the vcpus are stopped, so no write 1980 * operation will be performed. Block layer already has assertions to 1981 * ensure that. */ 1982 blk_set_force_allow_inactivate(s->target); 1983 } 1984 blk_set_allow_aio_context_change(s->target, true); 1985 blk_set_disable_request_queuing(s->target, true); 1986 1987 bdrv_graph_rdlock_main_loop(); 1988 s->replaces = g_strdup(replaces); 1989 s->on_source_error = on_source_error; 1990 s->on_target_error = on_target_error; 1991 s->sync_mode = sync_mode; 1992 s->backing_mode = backing_mode; 1993 s->target_is_zero = target_is_zero; 1994 qatomic_set(&s->copy_mode, copy_mode); 1995 s->base = base; 1996 s->base_overlay = bdrv_find_overlay(bs, base); 1997 s->granularity = granularity; 1998 s->buf_size = ROUND_UP(buf_size, granularity); 1999 s->unmap = unmap; 2000 if (auto_complete) { 2001 s->should_complete = true; 2002 } 2003 bdrv_graph_rdunlock_main_loop(); 2004 2005 s->dirty_bitmap = bdrv_create_dirty_bitmap(s->mirror_top_bs, granularity, 2006 NULL, errp); 2007 if (!s->dirty_bitmap) { 2008 goto fail; 2009 } 2010 2011 /* 2012 * The dirty bitmap is set by bdrv_mirror_top_do_write() when not in active 2013 * mode. 2014 */ 2015 bdrv_disable_dirty_bitmap(s->dirty_bitmap); 2016 2017 bdrv_graph_wrlock(); 2018 ret = block_job_add_bdrv(&s->common, "source", bs, 0, 2019 BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE | 2020 BLK_PERM_CONSISTENT_READ, 2021 errp); 2022 if (ret < 0) { 2023 bdrv_graph_wrunlock(); 2024 goto fail; 2025 } 2026 2027 /* Required permissions are already taken with blk_new() */ 2028 block_job_add_bdrv(&s->common, "target", target, 0, BLK_PERM_ALL, 2029 &error_abort); 2030 2031 /* In commit_active_start() all intermediate nodes disappear, so 2032 * any jobs in them must be blocked */ 2033 if (target_is_backing) { 2034 BlockDriverState *iter, *filtered_target; 2035 uint64_t iter_shared_perms; 2036 2037 /* 2038 * The topmost node with 2039 * bdrv_skip_filters(filtered_target) == bdrv_skip_filters(target) 2040 */ 2041 filtered_target = bdrv_cow_bs(bdrv_find_overlay(bs, target)); 2042 2043 assert(bdrv_skip_filters(filtered_target) == 2044 bdrv_skip_filters(target)); 2045 2046 /* 2047 * XXX BLK_PERM_WRITE needs to be allowed so we don't block 2048 * ourselves at s->base (if writes are blocked for a node, they are 2049 * also blocked for its backing file). The other options would be a 2050 * second filter driver above s->base (== target). 2051 */ 2052 iter_shared_perms = BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE; 2053 2054 for (iter = bdrv_filter_or_cow_bs(bs); iter != target; 2055 iter = bdrv_filter_or_cow_bs(iter)) 2056 { 2057 if (iter == filtered_target) { 2058 /* 2059 * From here on, all nodes are filters on the base. 2060 * This allows us to share BLK_PERM_CONSISTENT_READ. 2061 */ 2062 iter_shared_perms |= BLK_PERM_CONSISTENT_READ; 2063 } 2064 2065 ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, 2066 iter_shared_perms, errp); 2067 if (ret < 0) { 2068 bdrv_graph_wrunlock(); 2069 goto fail; 2070 } 2071 } 2072 2073 if (bdrv_freeze_backing_chain(mirror_top_bs, target, errp) < 0) { 2074 bdrv_graph_wrunlock(); 2075 goto fail; 2076 } 2077 } 2078 bdrv_graph_wrunlock(); 2079 2080 QTAILQ_INIT(&s->ops_in_flight); 2081 2082 trace_mirror_start(bs, s, opaque); 2083 job_start(&s->common.job); 2084 2085 return &s->common; 2086 2087 fail: 2088 if (s) { 2089 /* Make sure this BDS does not go away until we have completed the graph 2090 * changes below */ 2091 bdrv_ref(mirror_top_bs); 2092 2093 g_free(s->replaces); 2094 blk_unref(s->target); 2095 bs_opaque->job = NULL; 2096 if (s->dirty_bitmap) { 2097 bdrv_release_dirty_bitmap(s->dirty_bitmap); 2098 } 2099 job_early_fail(&s->common.job); 2100 } 2101 2102 bs_opaque->stop = true; 2103 bdrv_drained_begin(bs); 2104 bdrv_graph_wrlock(); 2105 assert(mirror_top_bs->backing->bs == bs); 2106 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 2107 &error_abort); 2108 bdrv_replace_node(mirror_top_bs, bs, &error_abort); 2109 bdrv_graph_wrunlock(); 2110 bdrv_drained_end(bs); 2111 2112 bdrv_unref(mirror_top_bs); 2113 2114 return NULL; 2115 } 2116 2117 void mirror_start(const char *job_id, BlockDriverState *bs, 2118 BlockDriverState *target, const char *replaces, 2119 int creation_flags, int64_t speed, 2120 uint32_t granularity, int64_t buf_size, 2121 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, 2122 bool target_is_zero, 2123 BlockdevOnError on_source_error, 2124 BlockdevOnError on_target_error, 2125 bool unmap, const char *filter_node_name, 2126 MirrorCopyMode copy_mode, Error **errp) 2127 { 2128 BlockDriverState *base; 2129 2130 GLOBAL_STATE_CODE(); 2131 2132 if ((mode == MIRROR_SYNC_MODE_INCREMENTAL) || 2133 (mode == MIRROR_SYNC_MODE_BITMAP)) { 2134 error_setg(errp, "Sync mode '%s' not supported", 2135 MirrorSyncMode_str(mode)); 2136 return; 2137 } 2138 2139 bdrv_graph_rdlock_main_loop(); 2140 base = mode == MIRROR_SYNC_MODE_TOP ? bdrv_backing_chain_next(bs) : NULL; 2141 bdrv_graph_rdunlock_main_loop(); 2142 2143 mirror_start_job(job_id, bs, creation_flags, target, replaces, 2144 speed, granularity, buf_size, mode, backing_mode, 2145 target_is_zero, on_source_error, on_target_error, unmap, 2146 NULL, NULL, &mirror_job_driver, base, false, 2147 filter_node_name, true, copy_mode, false, errp); 2148 } 2149 2150 BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs, 2151 BlockDriverState *base, int creation_flags, 2152 int64_t speed, BlockdevOnError on_error, 2153 const char *filter_node_name, 2154 BlockCompletionFunc *cb, void *opaque, 2155 bool auto_complete, Error **errp) 2156 { 2157 bool base_read_only; 2158 BlockJob *job; 2159 2160 GLOBAL_STATE_CODE(); 2161 2162 base_read_only = bdrv_is_read_only(base); 2163 2164 if (base_read_only) { 2165 if (bdrv_reopen_set_read_only(base, false, errp) < 0) { 2166 return NULL; 2167 } 2168 } 2169 2170 job = mirror_start_job( 2171 job_id, bs, creation_flags, base, NULL, speed, 0, 0, 2172 MIRROR_SYNC_MODE_TOP, MIRROR_LEAVE_BACKING_CHAIN, false, 2173 on_error, on_error, true, cb, opaque, 2174 &commit_active_job_driver, base, auto_complete, 2175 filter_node_name, false, MIRROR_COPY_MODE_BACKGROUND, 2176 base_read_only, errp); 2177 if (!job) { 2178 goto error_restore_flags; 2179 } 2180 2181 return job; 2182 2183 error_restore_flags: 2184 /* ignore error and errp for bdrv_reopen, because we want to propagate 2185 * the original error */ 2186 if (base_read_only) { 2187 bdrv_reopen_set_read_only(base, true, NULL); 2188 } 2189 return NULL; 2190 } 2191