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 AioContext *replace_aio_context = NULL; 666 BlockDriverState *src; 667 BlockDriverState *target_bs; 668 BlockDriverState *mirror_top_bs; 669 Error *local_err = NULL; 670 bool abort = job->ret < 0; 671 int ret = 0; 672 673 GLOBAL_STATE_CODE(); 674 675 if (s->prepared) { 676 return 0; 677 } 678 s->prepared = true; 679 680 aio_context_acquire(qemu_get_aio_context()); 681 bdrv_graph_rdlock_main_loop(); 682 683 mirror_top_bs = s->mirror_top_bs; 684 bs_opaque = mirror_top_bs->opaque; 685 src = mirror_top_bs->backing->bs; 686 target_bs = blk_bs(s->target); 687 688 if (bdrv_chain_contains(src, target_bs)) { 689 bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs); 690 } 691 692 bdrv_release_dirty_bitmap(s->dirty_bitmap); 693 694 /* Make sure that the source BDS doesn't go away during bdrv_replace_node, 695 * before we can call bdrv_drained_end */ 696 bdrv_ref(src); 697 bdrv_ref(mirror_top_bs); 698 bdrv_ref(target_bs); 699 700 bdrv_graph_rdunlock_main_loop(); 701 702 /* 703 * Remove target parent that still uses BLK_PERM_WRITE/RESIZE before 704 * inserting target_bs at s->to_replace, where we might not be able to get 705 * these permissions. 706 */ 707 blk_unref(s->target); 708 s->target = NULL; 709 710 /* We don't access the source any more. Dropping any WRITE/RESIZE is 711 * required before it could become a backing file of target_bs. Not having 712 * these permissions any more means that we can't allow any new requests on 713 * mirror_top_bs from now on, so keep it drained. */ 714 bdrv_drained_begin(mirror_top_bs); 715 bdrv_drained_begin(target_bs); 716 bs_opaque->stop = true; 717 718 bdrv_graph_rdlock_main_loop(); 719 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 720 &error_abort); 721 722 if (!abort && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { 723 BlockDriverState *backing = s->is_none_mode ? src : s->base; 724 BlockDriverState *unfiltered_target = bdrv_skip_filters(target_bs); 725 726 if (bdrv_cow_bs(unfiltered_target) != backing) { 727 bdrv_set_backing_hd(unfiltered_target, backing, &local_err); 728 if (local_err) { 729 error_report_err(local_err); 730 local_err = NULL; 731 ret = -EPERM; 732 } 733 } 734 } else if (!abort && s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { 735 assert(!bdrv_backing_chain_next(target_bs)); 736 ret = bdrv_open_backing_file(bdrv_skip_filters(target_bs), NULL, 737 "backing", &local_err); 738 if (ret < 0) { 739 error_report_err(local_err); 740 local_err = NULL; 741 } 742 } 743 bdrv_graph_rdunlock_main_loop(); 744 745 if (s->to_replace) { 746 replace_aio_context = bdrv_get_aio_context(s->to_replace); 747 aio_context_acquire(replace_aio_context); 748 } 749 750 if (s->should_complete && !abort) { 751 BlockDriverState *to_replace = s->to_replace ?: src; 752 bool ro = bdrv_is_read_only(to_replace); 753 754 if (ro != bdrv_is_read_only(target_bs)) { 755 bdrv_reopen_set_read_only(target_bs, ro, NULL); 756 } 757 758 /* The mirror job has no requests in flight any more, but we need to 759 * drain potential other users of the BDS before changing the graph. */ 760 assert(s->in_drain); 761 bdrv_drained_begin(to_replace); 762 /* 763 * Cannot use check_to_replace_node() here, because that would 764 * check for an op blocker on @to_replace, and we have our own 765 * there. 766 */ 767 bdrv_graph_wrlock(target_bs); 768 if (bdrv_recurse_can_replace(src, to_replace)) { 769 bdrv_replace_node(to_replace, target_bs, &local_err); 770 } else { 771 error_setg(&local_err, "Can no longer replace '%s' by '%s', " 772 "because it can no longer be guaranteed that doing so " 773 "would not lead to an abrupt change of visible data", 774 to_replace->node_name, target_bs->node_name); 775 } 776 bdrv_graph_wrunlock(); 777 bdrv_drained_end(to_replace); 778 if (local_err) { 779 error_report_err(local_err); 780 ret = -EPERM; 781 } 782 } 783 if (s->to_replace) { 784 bdrv_op_unblock_all(s->to_replace, s->replace_blocker); 785 error_free(s->replace_blocker); 786 bdrv_unref(s->to_replace); 787 } 788 if (replace_aio_context) { 789 aio_context_release(replace_aio_context); 790 } 791 g_free(s->replaces); 792 793 /* 794 * Remove the mirror filter driver from the graph. Before this, get rid of 795 * the blockers on the intermediate nodes so that the resulting state is 796 * valid. 797 */ 798 block_job_remove_all_bdrv(bjob); 799 bdrv_graph_wrlock(mirror_top_bs); 800 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort); 801 bdrv_graph_wrunlock(); 802 803 bdrv_drained_end(target_bs); 804 bdrv_unref(target_bs); 805 806 bs_opaque->job = NULL; 807 808 bdrv_drained_end(src); 809 bdrv_drained_end(mirror_top_bs); 810 s->in_drain = false; 811 bdrv_unref(mirror_top_bs); 812 bdrv_unref(src); 813 814 aio_context_release(qemu_get_aio_context()); 815 816 return ret; 817 } 818 819 static int mirror_prepare(Job *job) 820 { 821 return mirror_exit_common(job); 822 } 823 824 static void mirror_abort(Job *job) 825 { 826 int ret = mirror_exit_common(job); 827 assert(ret == 0); 828 } 829 830 static void coroutine_fn mirror_throttle(MirrorBlockJob *s) 831 { 832 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 833 834 if (now - s->last_pause_ns > BLOCK_JOB_SLICE_TIME) { 835 s->last_pause_ns = now; 836 job_sleep_ns(&s->common.job, 0); 837 } else { 838 job_pause_point(&s->common.job); 839 } 840 } 841 842 static int coroutine_fn GRAPH_UNLOCKED mirror_dirty_init(MirrorBlockJob *s) 843 { 844 int64_t offset; 845 BlockDriverState *bs; 846 BlockDriverState *target_bs = blk_bs(s->target); 847 int ret; 848 int64_t count; 849 850 bdrv_graph_co_rdlock(); 851 bs = s->mirror_top_bs->backing->bs; 852 bdrv_graph_co_rdunlock(); 853 854 if (s->zero_target) { 855 if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { 856 bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length); 857 return 0; 858 } 859 860 s->initial_zeroing_ongoing = true; 861 for (offset = 0; offset < s->bdev_length; ) { 862 int bytes = MIN(s->bdev_length - offset, 863 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 864 865 mirror_throttle(s); 866 867 if (job_is_cancelled(&s->common.job)) { 868 s->initial_zeroing_ongoing = false; 869 return 0; 870 } 871 872 if (s->in_flight >= MAX_IN_FLIGHT) { 873 trace_mirror_yield(s, UINT64_MAX, s->buf_free_count, 874 s->in_flight); 875 mirror_wait_for_free_in_flight_slot(s); 876 continue; 877 } 878 879 mirror_perform(s, offset, bytes, MIRROR_METHOD_ZERO); 880 offset += bytes; 881 } 882 883 mirror_wait_for_all_io(s); 884 s->initial_zeroing_ongoing = false; 885 } 886 887 /* First part, loop on the sectors and initialize the dirty bitmap. */ 888 for (offset = 0; offset < s->bdev_length; ) { 889 /* Just to make sure we are not exceeding int limit. */ 890 int bytes = MIN(s->bdev_length - offset, 891 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 892 893 mirror_throttle(s); 894 895 if (job_is_cancelled(&s->common.job)) { 896 return 0; 897 } 898 899 WITH_GRAPH_RDLOCK_GUARD() { 900 ret = bdrv_co_is_allocated_above(bs, s->base_overlay, true, offset, 901 bytes, &count); 902 } 903 if (ret < 0) { 904 return ret; 905 } 906 907 assert(count); 908 if (ret > 0) { 909 bdrv_set_dirty_bitmap(s->dirty_bitmap, offset, count); 910 } 911 offset += count; 912 } 913 return 0; 914 } 915 916 /* Called when going out of the streaming phase to flush the bulk of the 917 * data to the medium, or just before completing. 918 */ 919 static int coroutine_fn mirror_flush(MirrorBlockJob *s) 920 { 921 int ret = blk_co_flush(s->target); 922 if (ret < 0) { 923 if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) { 924 s->ret = ret; 925 } 926 } 927 return ret; 928 } 929 930 static int coroutine_fn mirror_run(Job *job, Error **errp) 931 { 932 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 933 BlockDriverState *bs; 934 MirrorBDSOpaque *mirror_top_opaque = s->mirror_top_bs->opaque; 935 BlockDriverState *target_bs = blk_bs(s->target); 936 bool need_drain = true; 937 BlockDeviceIoStatus iostatus; 938 int64_t length; 939 int64_t target_length; 940 BlockDriverInfo bdi; 941 char backing_filename[2]; /* we only need 2 characters because we are only 942 checking for a NULL string */ 943 int ret = 0; 944 945 bdrv_graph_co_rdlock(); 946 bs = bdrv_filter_bs(s->mirror_top_bs); 947 bdrv_graph_co_rdunlock(); 948 949 if (job_is_cancelled(&s->common.job)) { 950 goto immediate_exit; 951 } 952 953 bdrv_graph_co_rdlock(); 954 s->bdev_length = bdrv_co_getlength(bs); 955 bdrv_graph_co_rdunlock(); 956 957 if (s->bdev_length < 0) { 958 ret = s->bdev_length; 959 goto immediate_exit; 960 } 961 962 target_length = blk_co_getlength(s->target); 963 if (target_length < 0) { 964 ret = target_length; 965 goto immediate_exit; 966 } 967 968 /* Active commit must resize the base image if its size differs from the 969 * active layer. */ 970 if (s->base == blk_bs(s->target)) { 971 if (s->bdev_length > target_length) { 972 ret = blk_co_truncate(s->target, s->bdev_length, false, 973 PREALLOC_MODE_OFF, 0, NULL); 974 if (ret < 0) { 975 goto immediate_exit; 976 } 977 } 978 } else if (s->bdev_length != target_length) { 979 error_setg(errp, "Source and target image have different sizes"); 980 ret = -EINVAL; 981 goto immediate_exit; 982 } 983 984 if (s->bdev_length == 0) { 985 /* Transition to the READY state and wait for complete. */ 986 job_transition_to_ready(&s->common.job); 987 qatomic_set(&s->actively_synced, true); 988 while (!job_cancel_requested(&s->common.job) && !s->should_complete) { 989 job_yield(&s->common.job); 990 } 991 goto immediate_exit; 992 } 993 994 length = DIV_ROUND_UP(s->bdev_length, s->granularity); 995 s->in_flight_bitmap = bitmap_new(length); 996 997 /* If we have no backing file yet in the destination, we cannot let 998 * the destination do COW. Instead, we copy sectors around the 999 * dirty data if needed. We need a bitmap to do that. 1000 */ 1001 bdrv_get_backing_filename(target_bs, backing_filename, 1002 sizeof(backing_filename)); 1003 bdrv_graph_co_rdlock(); 1004 if (!bdrv_co_get_info(target_bs, &bdi) && bdi.cluster_size) { 1005 s->target_cluster_size = bdi.cluster_size; 1006 } else { 1007 s->target_cluster_size = BDRV_SECTOR_SIZE; 1008 } 1009 if (backing_filename[0] && !bdrv_backing_chain_next(target_bs) && 1010 s->granularity < s->target_cluster_size) { 1011 s->buf_size = MAX(s->buf_size, s->target_cluster_size); 1012 s->cow_bitmap = bitmap_new(length); 1013 } 1014 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); 1015 bdrv_graph_co_rdunlock(); 1016 1017 s->buf = qemu_try_blockalign(bs, s->buf_size); 1018 if (s->buf == NULL) { 1019 ret = -ENOMEM; 1020 goto immediate_exit; 1021 } 1022 1023 mirror_free_init(s); 1024 1025 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 1026 if (!s->is_none_mode) { 1027 ret = mirror_dirty_init(s); 1028 if (ret < 0 || job_is_cancelled(&s->common.job)) { 1029 goto immediate_exit; 1030 } 1031 } 1032 1033 /* 1034 * Only now the job is fully initialised and mirror_top_bs should start 1035 * accessing it. 1036 */ 1037 mirror_top_opaque->job = s; 1038 1039 assert(!s->dbi); 1040 s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap); 1041 for (;;) { 1042 int64_t cnt, delta; 1043 bool should_complete; 1044 1045 if (s->ret < 0) { 1046 ret = s->ret; 1047 goto immediate_exit; 1048 } 1049 1050 job_pause_point(&s->common.job); 1051 1052 if (job_is_cancelled(&s->common.job)) { 1053 ret = 0; 1054 goto immediate_exit; 1055 } 1056 1057 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1058 /* cnt is the number of dirty bytes remaining and s->bytes_in_flight is 1059 * the number of bytes currently being processed; together those are 1060 * the current remaining operation length */ 1061 job_progress_set_remaining(&s->common.job, 1062 s->bytes_in_flight + cnt + 1063 s->active_write_bytes_in_flight); 1064 1065 /* Note that even when no rate limit is applied we need to yield 1066 * periodically with no pending I/O so that bdrv_drain_all() returns. 1067 * We do so every BLKOCK_JOB_SLICE_TIME nanoseconds, or when there is 1068 * an error, or when the source is clean, whichever comes first. */ 1069 delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns; 1070 WITH_JOB_LOCK_GUARD() { 1071 iostatus = s->common.iostatus; 1072 } 1073 if (delta < BLOCK_JOB_SLICE_TIME && 1074 iostatus == BLOCK_DEVICE_IO_STATUS_OK) { 1075 if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || 1076 (cnt == 0 && s->in_flight > 0)) { 1077 trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight); 1078 mirror_wait_for_free_in_flight_slot(s); 1079 continue; 1080 } else if (cnt != 0) { 1081 bdrv_graph_co_rdlock(); 1082 mirror_iteration(s); 1083 bdrv_graph_co_rdunlock(); 1084 } 1085 } 1086 1087 should_complete = false; 1088 if (s->in_flight == 0 && cnt == 0) { 1089 trace_mirror_before_flush(s); 1090 if (!job_is_ready(&s->common.job)) { 1091 if (mirror_flush(s) < 0) { 1092 /* Go check s->ret. */ 1093 continue; 1094 } 1095 /* We're out of the streaming phase. From now on, if the job 1096 * is cancelled we will actually complete all pending I/O and 1097 * report completion. This way, block-job-cancel will leave 1098 * the target in a consistent state. 1099 */ 1100 job_transition_to_ready(&s->common.job); 1101 } 1102 if (qatomic_read(&s->copy_mode) != MIRROR_COPY_MODE_BACKGROUND) { 1103 qatomic_set(&s->actively_synced, true); 1104 } 1105 1106 should_complete = s->should_complete || 1107 job_cancel_requested(&s->common.job); 1108 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1109 } 1110 1111 if (cnt == 0 && should_complete) { 1112 /* The dirty bitmap is not updated while operations are pending. 1113 * If we're about to exit, wait for pending operations before 1114 * calling bdrv_get_dirty_count(bs), or we may exit while the 1115 * source has dirty data to copy! 1116 * 1117 * Note that I/O can be submitted by the guest while 1118 * mirror_populate runs, so pause it now. Before deciding 1119 * whether to switch to target check one last time if I/O has 1120 * come in the meanwhile, and if not flush the data to disk. 1121 */ 1122 trace_mirror_before_drain(s, cnt); 1123 1124 s->in_drain = true; 1125 bdrv_drained_begin(bs); 1126 1127 /* Must be zero because we are drained */ 1128 assert(s->in_active_write_counter == 0); 1129 1130 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1131 if (cnt > 0 || mirror_flush(s) < 0) { 1132 bdrv_drained_end(bs); 1133 s->in_drain = false; 1134 continue; 1135 } 1136 1137 /* The two disks are in sync. Exit and report successful 1138 * completion. 1139 */ 1140 assert(QLIST_EMPTY(&bs->tracked_requests)); 1141 need_drain = false; 1142 break; 1143 } 1144 1145 if (job_is_ready(&s->common.job) && !should_complete) { 1146 if (s->in_flight == 0 && cnt == 0) { 1147 trace_mirror_before_sleep(s, cnt, job_is_ready(&s->common.job), 1148 BLOCK_JOB_SLICE_TIME); 1149 job_sleep_ns(&s->common.job, BLOCK_JOB_SLICE_TIME); 1150 } 1151 } else { 1152 block_job_ratelimit_sleep(&s->common); 1153 } 1154 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 1155 } 1156 1157 immediate_exit: 1158 if (s->in_flight > 0) { 1159 /* We get here only if something went wrong. Either the job failed, 1160 * or it was cancelled prematurely so that we do not guarantee that 1161 * the target is a copy of the source. 1162 */ 1163 assert(ret < 0 || job_is_cancelled(&s->common.job)); 1164 assert(need_drain); 1165 mirror_wait_for_all_io(s); 1166 } 1167 1168 assert(s->in_flight == 0); 1169 qemu_vfree(s->buf); 1170 g_free(s->cow_bitmap); 1171 g_free(s->in_flight_bitmap); 1172 bdrv_dirty_iter_free(s->dbi); 1173 1174 if (need_drain) { 1175 s->in_drain = true; 1176 bdrv_drained_begin(bs); 1177 } 1178 1179 return ret; 1180 } 1181 1182 static void mirror_complete(Job *job, Error **errp) 1183 { 1184 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1185 1186 if (!job_is_ready(job)) { 1187 error_setg(errp, "The active block job '%s' cannot be completed", 1188 job->id); 1189 return; 1190 } 1191 1192 /* block all operations on to_replace bs */ 1193 if (s->replaces) { 1194 AioContext *replace_aio_context; 1195 1196 s->to_replace = bdrv_find_node(s->replaces); 1197 if (!s->to_replace) { 1198 error_setg(errp, "Node name '%s' not found", s->replaces); 1199 return; 1200 } 1201 1202 replace_aio_context = bdrv_get_aio_context(s->to_replace); 1203 aio_context_acquire(replace_aio_context); 1204 1205 /* TODO Translate this into child freeze system. */ 1206 error_setg(&s->replace_blocker, 1207 "block device is in use by block-job-complete"); 1208 bdrv_op_block_all(s->to_replace, s->replace_blocker); 1209 bdrv_ref(s->to_replace); 1210 1211 aio_context_release(replace_aio_context); 1212 } 1213 1214 s->should_complete = true; 1215 1216 /* If the job is paused, it will be re-entered when it is resumed */ 1217 WITH_JOB_LOCK_GUARD() { 1218 if (!job->paused) { 1219 job_enter_cond_locked(job, NULL); 1220 } 1221 } 1222 } 1223 1224 static void coroutine_fn mirror_pause(Job *job) 1225 { 1226 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1227 1228 mirror_wait_for_all_io(s); 1229 } 1230 1231 static bool mirror_drained_poll(BlockJob *job) 1232 { 1233 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1234 1235 /* If the job isn't paused nor cancelled, we can't be sure that it won't 1236 * issue more requests. We make an exception if we've reached this point 1237 * from one of our own drain sections, to avoid a deadlock waiting for 1238 * ourselves. 1239 */ 1240 WITH_JOB_LOCK_GUARD() { 1241 if (!s->common.job.paused && !job_is_cancelled_locked(&job->job) 1242 && !s->in_drain) { 1243 return true; 1244 } 1245 } 1246 1247 return !!s->in_flight; 1248 } 1249 1250 static bool mirror_cancel(Job *job, bool force) 1251 { 1252 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1253 BlockDriverState *target = blk_bs(s->target); 1254 1255 /* 1256 * Before the job is READY, we treat any cancellation like a 1257 * force-cancellation. 1258 */ 1259 force = force || !job_is_ready(job); 1260 1261 if (force) { 1262 bdrv_cancel_in_flight(target); 1263 } 1264 return force; 1265 } 1266 1267 static bool commit_active_cancel(Job *job, bool force) 1268 { 1269 /* Same as above in mirror_cancel() */ 1270 return force || !job_is_ready(job); 1271 } 1272 1273 static void mirror_change(BlockJob *job, BlockJobChangeOptions *opts, 1274 Error **errp) 1275 { 1276 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1277 BlockJobChangeOptionsMirror *change_opts = &opts->u.mirror; 1278 MirrorCopyMode current; 1279 1280 /* 1281 * The implementation relies on the fact that copy_mode is only written 1282 * under the BQL. Otherwise, further synchronization would be required. 1283 */ 1284 1285 GLOBAL_STATE_CODE(); 1286 1287 if (qatomic_read(&s->copy_mode) == change_opts->copy_mode) { 1288 return; 1289 } 1290 1291 if (change_opts->copy_mode != MIRROR_COPY_MODE_WRITE_BLOCKING) { 1292 error_setg(errp, "Change to copy mode '%s' is not implemented", 1293 MirrorCopyMode_str(change_opts->copy_mode)); 1294 return; 1295 } 1296 1297 current = qatomic_cmpxchg(&s->copy_mode, MIRROR_COPY_MODE_BACKGROUND, 1298 change_opts->copy_mode); 1299 if (current != MIRROR_COPY_MODE_BACKGROUND) { 1300 error_setg(errp, "Expected current copy mode '%s', got '%s'", 1301 MirrorCopyMode_str(MIRROR_COPY_MODE_BACKGROUND), 1302 MirrorCopyMode_str(current)); 1303 } 1304 } 1305 1306 static void mirror_query(BlockJob *job, BlockJobInfo *info) 1307 { 1308 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1309 1310 info->u.mirror = (BlockJobInfoMirror) { 1311 .actively_synced = qatomic_read(&s->actively_synced), 1312 }; 1313 } 1314 1315 static const BlockJobDriver mirror_job_driver = { 1316 .job_driver = { 1317 .instance_size = sizeof(MirrorBlockJob), 1318 .job_type = JOB_TYPE_MIRROR, 1319 .free = block_job_free, 1320 .user_resume = block_job_user_resume, 1321 .run = mirror_run, 1322 .prepare = mirror_prepare, 1323 .abort = mirror_abort, 1324 .pause = mirror_pause, 1325 .complete = mirror_complete, 1326 .cancel = mirror_cancel, 1327 }, 1328 .drained_poll = mirror_drained_poll, 1329 .change = mirror_change, 1330 .query = mirror_query, 1331 }; 1332 1333 static const BlockJobDriver commit_active_job_driver = { 1334 .job_driver = { 1335 .instance_size = sizeof(MirrorBlockJob), 1336 .job_type = JOB_TYPE_COMMIT, 1337 .free = block_job_free, 1338 .user_resume = block_job_user_resume, 1339 .run = mirror_run, 1340 .prepare = mirror_prepare, 1341 .abort = mirror_abort, 1342 .pause = mirror_pause, 1343 .complete = mirror_complete, 1344 .cancel = commit_active_cancel, 1345 }, 1346 .drained_poll = mirror_drained_poll, 1347 }; 1348 1349 static void coroutine_fn 1350 do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, 1351 uint64_t offset, uint64_t bytes, 1352 QEMUIOVector *qiov, int flags) 1353 { 1354 int ret; 1355 size_t qiov_offset = 0; 1356 int64_t bitmap_offset, bitmap_end; 1357 1358 if (!QEMU_IS_ALIGNED(offset, job->granularity) && 1359 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset)) 1360 { 1361 /* 1362 * Dirty unaligned padding: ignore it. 1363 * 1364 * Reasoning: 1365 * 1. If we copy it, we can't reset corresponding bit in 1366 * dirty_bitmap as there may be some "dirty" bytes still not 1367 * copied. 1368 * 2. It's already dirty, so skipping it we don't diverge mirror 1369 * progress. 1370 * 1371 * Note, that because of this, guest write may have no contribution 1372 * into mirror converge, but that's not bad, as we have background 1373 * process of mirroring. If under some bad circumstances (high guest 1374 * IO load) background process starve, we will not converge anyway, 1375 * even if each write will contribute, as guest is not guaranteed to 1376 * rewrite the whole disk. 1377 */ 1378 qiov_offset = QEMU_ALIGN_UP(offset, job->granularity) - offset; 1379 if (bytes <= qiov_offset) { 1380 /* nothing to do after shrink */ 1381 return; 1382 } 1383 offset += qiov_offset; 1384 bytes -= qiov_offset; 1385 } 1386 1387 if (!QEMU_IS_ALIGNED(offset + bytes, job->granularity) && 1388 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset + bytes - 1)) 1389 { 1390 uint64_t tail = (offset + bytes) % job->granularity; 1391 1392 if (bytes <= tail) { 1393 /* nothing to do after shrink */ 1394 return; 1395 } 1396 bytes -= tail; 1397 } 1398 1399 /* 1400 * Tails are either clean or shrunk, so for bitmap resetting 1401 * we safely align the range down. 1402 */ 1403 bitmap_offset = QEMU_ALIGN_UP(offset, job->granularity); 1404 bitmap_end = QEMU_ALIGN_DOWN(offset + bytes, job->granularity); 1405 if (bitmap_offset < bitmap_end) { 1406 bdrv_reset_dirty_bitmap(job->dirty_bitmap, bitmap_offset, 1407 bitmap_end - bitmap_offset); 1408 } 1409 1410 job_progress_increase_remaining(&job->common.job, bytes); 1411 job->active_write_bytes_in_flight += bytes; 1412 1413 switch (method) { 1414 case MIRROR_METHOD_COPY: 1415 ret = blk_co_pwritev_part(job->target, offset, bytes, 1416 qiov, qiov_offset, flags); 1417 break; 1418 1419 case MIRROR_METHOD_ZERO: 1420 assert(!qiov); 1421 ret = blk_co_pwrite_zeroes(job->target, offset, bytes, flags); 1422 break; 1423 1424 case MIRROR_METHOD_DISCARD: 1425 assert(!qiov); 1426 ret = blk_co_pdiscard(job->target, offset, bytes); 1427 break; 1428 1429 default: 1430 abort(); 1431 } 1432 1433 job->active_write_bytes_in_flight -= bytes; 1434 if (ret >= 0) { 1435 job_progress_update(&job->common.job, bytes); 1436 } else { 1437 BlockErrorAction action; 1438 1439 /* 1440 * We failed, so we should mark dirty the whole area, aligned up. 1441 * Note that we don't care about shrunk tails if any: they were dirty 1442 * at function start, and they must be still dirty, as we've locked 1443 * the region for in-flight op. 1444 */ 1445 bitmap_offset = QEMU_ALIGN_DOWN(offset, job->granularity); 1446 bitmap_end = QEMU_ALIGN_UP(offset + bytes, job->granularity); 1447 bdrv_set_dirty_bitmap(job->dirty_bitmap, bitmap_offset, 1448 bitmap_end - bitmap_offset); 1449 qatomic_set(&job->actively_synced, false); 1450 1451 action = mirror_error_action(job, false, -ret); 1452 if (action == BLOCK_ERROR_ACTION_REPORT) { 1453 if (!job->ret) { 1454 job->ret = ret; 1455 } 1456 } 1457 } 1458 } 1459 1460 static MirrorOp *coroutine_fn active_write_prepare(MirrorBlockJob *s, 1461 uint64_t offset, 1462 uint64_t bytes) 1463 { 1464 MirrorOp *op; 1465 uint64_t start_chunk = offset / s->granularity; 1466 uint64_t end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 1467 1468 op = g_new(MirrorOp, 1); 1469 *op = (MirrorOp){ 1470 .s = s, 1471 .offset = offset, 1472 .bytes = bytes, 1473 .is_active_write = true, 1474 .is_in_flight = true, 1475 .co = qemu_coroutine_self(), 1476 }; 1477 qemu_co_queue_init(&op->waiting_requests); 1478 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 1479 1480 s->in_active_write_counter++; 1481 1482 /* 1483 * Wait for concurrent requests affecting the area. If there are already 1484 * running requests that are copying off now-to-be stale data in the area, 1485 * we must wait for them to finish before we begin writing fresh data to the 1486 * target so that the write operations appear in the correct order. 1487 * Note that background requests (see mirror_iteration()) in contrast only 1488 * wait for conflicting requests at the start of the dirty area, and then 1489 * (based on the in_flight_bitmap) truncate the area to copy so it will not 1490 * conflict with any requests beyond that. For active writes, however, we 1491 * cannot truncate that area. The request from our parent must be blocked 1492 * until the area is copied in full. Therefore, we must wait for the whole 1493 * area to become free of concurrent requests. 1494 */ 1495 mirror_wait_on_conflicts(op, s, offset, bytes); 1496 1497 bitmap_set(s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1498 1499 return op; 1500 } 1501 1502 static void coroutine_fn GRAPH_RDLOCK active_write_settle(MirrorOp *op) 1503 { 1504 uint64_t start_chunk = op->offset / op->s->granularity; 1505 uint64_t end_chunk = DIV_ROUND_UP(op->offset + op->bytes, 1506 op->s->granularity); 1507 1508 if (!--op->s->in_active_write_counter && 1509 qatomic_read(&op->s->actively_synced)) { 1510 BdrvChild *source = op->s->mirror_top_bs->backing; 1511 1512 if (QLIST_FIRST(&source->bs->parents) == source && 1513 QLIST_NEXT(source, next_parent) == NULL) 1514 { 1515 /* Assert that we are back in sync once all active write 1516 * operations are settled. 1517 * Note that we can only assert this if the mirror node 1518 * is the source node's only parent. */ 1519 assert(!bdrv_get_dirty_count(op->s->dirty_bitmap)); 1520 } 1521 } 1522 bitmap_clear(op->s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1523 QTAILQ_REMOVE(&op->s->ops_in_flight, op, next); 1524 qemu_co_queue_restart_all(&op->waiting_requests); 1525 g_free(op); 1526 } 1527 1528 static int coroutine_fn GRAPH_RDLOCK 1529 bdrv_mirror_top_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes, 1530 QEMUIOVector *qiov, BdrvRequestFlags flags) 1531 { 1532 return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); 1533 } 1534 1535 static bool should_copy_to_target(MirrorBDSOpaque *s) 1536 { 1537 return s->job && s->job->ret >= 0 && 1538 !job_is_cancelled(&s->job->common.job) && 1539 qatomic_read(&s->job->copy_mode) == MIRROR_COPY_MODE_WRITE_BLOCKING; 1540 } 1541 1542 static int coroutine_fn GRAPH_RDLOCK 1543 bdrv_mirror_top_do_write(BlockDriverState *bs, MirrorMethod method, 1544 bool copy_to_target, uint64_t offset, uint64_t bytes, 1545 QEMUIOVector *qiov, int flags) 1546 { 1547 MirrorOp *op = NULL; 1548 MirrorBDSOpaque *s = bs->opaque; 1549 int ret = 0; 1550 1551 if (copy_to_target) { 1552 op = active_write_prepare(s->job, offset, bytes); 1553 } 1554 1555 switch (method) { 1556 case MIRROR_METHOD_COPY: 1557 ret = bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags); 1558 break; 1559 1560 case MIRROR_METHOD_ZERO: 1561 ret = bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags); 1562 break; 1563 1564 case MIRROR_METHOD_DISCARD: 1565 ret = bdrv_co_pdiscard(bs->backing, offset, bytes); 1566 break; 1567 1568 default: 1569 abort(); 1570 } 1571 1572 if (!copy_to_target && s->job && s->job->dirty_bitmap) { 1573 qatomic_set(&s->job->actively_synced, false); 1574 bdrv_set_dirty_bitmap(s->job->dirty_bitmap, offset, bytes); 1575 } 1576 1577 if (ret < 0) { 1578 goto out; 1579 } 1580 1581 if (copy_to_target) { 1582 do_sync_target_write(s->job, method, offset, bytes, qiov, flags); 1583 } 1584 1585 out: 1586 if (copy_to_target) { 1587 active_write_settle(op); 1588 } 1589 return ret; 1590 } 1591 1592 static int coroutine_fn GRAPH_RDLOCK 1593 bdrv_mirror_top_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes, 1594 QEMUIOVector *qiov, BdrvRequestFlags flags) 1595 { 1596 QEMUIOVector bounce_qiov; 1597 void *bounce_buf; 1598 int ret = 0; 1599 bool copy_to_target = should_copy_to_target(bs->opaque); 1600 1601 if (copy_to_target) { 1602 /* The guest might concurrently modify the data to write; but 1603 * the data on source and destination must match, so we have 1604 * to use a bounce buffer if we are going to write to the 1605 * target now. */ 1606 bounce_buf = qemu_blockalign(bs, bytes); 1607 iov_to_buf_full(qiov->iov, qiov->niov, 0, bounce_buf, bytes); 1608 1609 qemu_iovec_init(&bounce_qiov, 1); 1610 qemu_iovec_add(&bounce_qiov, bounce_buf, bytes); 1611 qiov = &bounce_qiov; 1612 1613 flags &= ~BDRV_REQ_REGISTERED_BUF; 1614 } 1615 1616 ret = bdrv_mirror_top_do_write(bs, MIRROR_METHOD_COPY, copy_to_target, 1617 offset, bytes, qiov, flags); 1618 1619 if (copy_to_target) { 1620 qemu_iovec_destroy(&bounce_qiov); 1621 qemu_vfree(bounce_buf); 1622 } 1623 1624 return ret; 1625 } 1626 1627 static int coroutine_fn GRAPH_RDLOCK bdrv_mirror_top_flush(BlockDriverState *bs) 1628 { 1629 if (bs->backing == NULL) { 1630 /* we can be here after failed bdrv_append in mirror_start_job */ 1631 return 0; 1632 } 1633 return bdrv_co_flush(bs->backing->bs); 1634 } 1635 1636 static int coroutine_fn GRAPH_RDLOCK 1637 bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs, int64_t offset, 1638 int64_t bytes, BdrvRequestFlags flags) 1639 { 1640 bool copy_to_target = should_copy_to_target(bs->opaque); 1641 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_ZERO, copy_to_target, 1642 offset, bytes, NULL, flags); 1643 } 1644 1645 static int coroutine_fn GRAPH_RDLOCK 1646 bdrv_mirror_top_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes) 1647 { 1648 bool copy_to_target = should_copy_to_target(bs->opaque); 1649 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_DISCARD, copy_to_target, 1650 offset, bytes, NULL, 0); 1651 } 1652 1653 static void GRAPH_RDLOCK bdrv_mirror_top_refresh_filename(BlockDriverState *bs) 1654 { 1655 if (bs->backing == NULL) { 1656 /* we can be here after failed bdrv_attach_child in 1657 * bdrv_set_backing_hd */ 1658 return; 1659 } 1660 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), 1661 bs->backing->bs->filename); 1662 } 1663 1664 static void bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c, 1665 BdrvChildRole role, 1666 BlockReopenQueue *reopen_queue, 1667 uint64_t perm, uint64_t shared, 1668 uint64_t *nperm, uint64_t *nshared) 1669 { 1670 MirrorBDSOpaque *s = bs->opaque; 1671 1672 if (s->stop) { 1673 /* 1674 * If the job is to be stopped, we do not need to forward 1675 * anything to the real image. 1676 */ 1677 *nperm = 0; 1678 *nshared = BLK_PERM_ALL; 1679 return; 1680 } 1681 1682 bdrv_default_perms(bs, c, role, reopen_queue, 1683 perm, shared, nperm, nshared); 1684 1685 if (s->is_commit) { 1686 /* 1687 * For commit jobs, we cannot take CONSISTENT_READ, because 1688 * that permission is unshared for everything above the base 1689 * node (except for filters on the base node). 1690 * We also have to force-share the WRITE permission, or 1691 * otherwise we would block ourselves at the base node (if 1692 * writes are blocked for a node, they are also blocked for 1693 * its backing file). 1694 * (We could also share RESIZE, because it may be needed for 1695 * the target if its size is less than the top node's; but 1696 * bdrv_default_perms_for_cow() automatically shares RESIZE 1697 * for backing nodes if WRITE is shared, so there is no need 1698 * to do it here.) 1699 */ 1700 *nperm &= ~BLK_PERM_CONSISTENT_READ; 1701 *nshared |= BLK_PERM_WRITE; 1702 } 1703 } 1704 1705 /* Dummy node that provides consistent read to its users without requiring it 1706 * from its backing file and that allows writes on the backing file chain. */ 1707 static BlockDriver bdrv_mirror_top = { 1708 .format_name = "mirror_top", 1709 .bdrv_co_preadv = bdrv_mirror_top_preadv, 1710 .bdrv_co_pwritev = bdrv_mirror_top_pwritev, 1711 .bdrv_co_pwrite_zeroes = bdrv_mirror_top_pwrite_zeroes, 1712 .bdrv_co_pdiscard = bdrv_mirror_top_pdiscard, 1713 .bdrv_co_flush = bdrv_mirror_top_flush, 1714 .bdrv_refresh_filename = bdrv_mirror_top_refresh_filename, 1715 .bdrv_child_perm = bdrv_mirror_top_child_perm, 1716 1717 .is_filter = true, 1718 .filtered_child_is_backing = true, 1719 }; 1720 1721 static BlockJob *mirror_start_job( 1722 const char *job_id, BlockDriverState *bs, 1723 int creation_flags, BlockDriverState *target, 1724 const char *replaces, int64_t speed, 1725 uint32_t granularity, int64_t buf_size, 1726 BlockMirrorBackingMode backing_mode, 1727 bool zero_target, 1728 BlockdevOnError on_source_error, 1729 BlockdevOnError on_target_error, 1730 bool unmap, 1731 BlockCompletionFunc *cb, 1732 void *opaque, 1733 const BlockJobDriver *driver, 1734 bool is_none_mode, BlockDriverState *base, 1735 bool auto_complete, const char *filter_node_name, 1736 bool is_mirror, MirrorCopyMode copy_mode, 1737 Error **errp) 1738 { 1739 MirrorBlockJob *s; 1740 MirrorBDSOpaque *bs_opaque; 1741 BlockDriverState *mirror_top_bs; 1742 bool target_is_backing; 1743 uint64_t target_perms, target_shared_perms; 1744 int ret; 1745 1746 GLOBAL_STATE_CODE(); 1747 1748 if (granularity == 0) { 1749 granularity = bdrv_get_default_bitmap_granularity(target); 1750 } 1751 1752 assert(is_power_of_2(granularity)); 1753 1754 if (buf_size < 0) { 1755 error_setg(errp, "Invalid parameter 'buf-size'"); 1756 return NULL; 1757 } 1758 1759 if (buf_size == 0) { 1760 buf_size = DEFAULT_MIRROR_BUF_SIZE; 1761 } 1762 1763 bdrv_graph_rdlock_main_loop(); 1764 if (bdrv_skip_filters(bs) == bdrv_skip_filters(target)) { 1765 error_setg(errp, "Can't mirror node into itself"); 1766 bdrv_graph_rdunlock_main_loop(); 1767 return NULL; 1768 } 1769 1770 target_is_backing = bdrv_chain_contains(bs, target); 1771 bdrv_graph_rdunlock_main_loop(); 1772 1773 /* In the case of active commit, add dummy driver to provide consistent 1774 * reads on the top, while disabling it in the intermediate nodes, and make 1775 * the backing chain writable. */ 1776 mirror_top_bs = bdrv_new_open_driver(&bdrv_mirror_top, filter_node_name, 1777 BDRV_O_RDWR, errp); 1778 if (mirror_top_bs == NULL) { 1779 return NULL; 1780 } 1781 if (!filter_node_name) { 1782 mirror_top_bs->implicit = true; 1783 } 1784 1785 /* So that we can always drop this node */ 1786 mirror_top_bs->never_freeze = true; 1787 1788 mirror_top_bs->total_sectors = bs->total_sectors; 1789 mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED; 1790 mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED | 1791 BDRV_REQ_NO_FALLBACK; 1792 bs_opaque = g_new0(MirrorBDSOpaque, 1); 1793 mirror_top_bs->opaque = bs_opaque; 1794 1795 bs_opaque->is_commit = target_is_backing; 1796 1797 bdrv_drained_begin(bs); 1798 ret = bdrv_append(mirror_top_bs, bs, errp); 1799 bdrv_drained_end(bs); 1800 1801 if (ret < 0) { 1802 bdrv_unref(mirror_top_bs); 1803 return NULL; 1804 } 1805 1806 /* Make sure that the source is not resized while the job is running */ 1807 s = block_job_create(job_id, driver, NULL, mirror_top_bs, 1808 BLK_PERM_CONSISTENT_READ, 1809 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | 1810 BLK_PERM_WRITE, speed, 1811 creation_flags, cb, opaque, errp); 1812 if (!s) { 1813 goto fail; 1814 } 1815 1816 /* The block job now has a reference to this node */ 1817 bdrv_unref(mirror_top_bs); 1818 1819 s->mirror_top_bs = mirror_top_bs; 1820 1821 /* No resize for the target either; while the mirror is still running, a 1822 * consistent read isn't necessarily possible. We could possibly allow 1823 * writes and graph modifications, though it would likely defeat the 1824 * purpose of a mirror, so leave them blocked for now. 1825 * 1826 * In the case of active commit, things look a bit different, though, 1827 * because the target is an already populated backing file in active use. 1828 * We can allow anything except resize there.*/ 1829 1830 target_perms = BLK_PERM_WRITE; 1831 target_shared_perms = BLK_PERM_WRITE_UNCHANGED; 1832 1833 if (target_is_backing) { 1834 int64_t bs_size, target_size; 1835 bs_size = bdrv_getlength(bs); 1836 if (bs_size < 0) { 1837 error_setg_errno(errp, -bs_size, 1838 "Could not inquire top image size"); 1839 goto fail; 1840 } 1841 1842 target_size = bdrv_getlength(target); 1843 if (target_size < 0) { 1844 error_setg_errno(errp, -target_size, 1845 "Could not inquire base image size"); 1846 goto fail; 1847 } 1848 1849 if (target_size < bs_size) { 1850 target_perms |= BLK_PERM_RESIZE; 1851 } 1852 1853 target_shared_perms |= BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE; 1854 } else { 1855 bdrv_graph_rdlock_main_loop(); 1856 if (bdrv_chain_contains(bs, bdrv_skip_filters(target))) { 1857 /* 1858 * We may want to allow this in the future, but it would 1859 * require taking some extra care. 1860 */ 1861 error_setg(errp, "Cannot mirror to a filter on top of a node in " 1862 "the source's backing chain"); 1863 bdrv_graph_rdunlock_main_loop(); 1864 goto fail; 1865 } 1866 bdrv_graph_rdunlock_main_loop(); 1867 } 1868 1869 s->target = blk_new(s->common.job.aio_context, 1870 target_perms, target_shared_perms); 1871 ret = blk_insert_bs(s->target, target, errp); 1872 if (ret < 0) { 1873 goto fail; 1874 } 1875 if (is_mirror) { 1876 /* XXX: Mirror target could be a NBD server of target QEMU in the case 1877 * of non-shared block migration. To allow migration completion, we 1878 * have to allow "inactivate" of the target BB. When that happens, we 1879 * know the job is drained, and the vcpus are stopped, so no write 1880 * operation will be performed. Block layer already has assertions to 1881 * ensure that. */ 1882 blk_set_force_allow_inactivate(s->target); 1883 } 1884 blk_set_allow_aio_context_change(s->target, true); 1885 blk_set_disable_request_queuing(s->target, true); 1886 1887 bdrv_graph_rdlock_main_loop(); 1888 s->replaces = g_strdup(replaces); 1889 s->on_source_error = on_source_error; 1890 s->on_target_error = on_target_error; 1891 s->is_none_mode = is_none_mode; 1892 s->backing_mode = backing_mode; 1893 s->zero_target = zero_target; 1894 qatomic_set(&s->copy_mode, copy_mode); 1895 s->base = base; 1896 s->base_overlay = bdrv_find_overlay(bs, base); 1897 s->granularity = granularity; 1898 s->buf_size = ROUND_UP(buf_size, granularity); 1899 s->unmap = unmap; 1900 if (auto_complete) { 1901 s->should_complete = true; 1902 } 1903 bdrv_graph_rdunlock_main_loop(); 1904 1905 s->dirty_bitmap = bdrv_create_dirty_bitmap(s->mirror_top_bs, granularity, 1906 NULL, errp); 1907 if (!s->dirty_bitmap) { 1908 goto fail; 1909 } 1910 1911 /* 1912 * The dirty bitmap is set by bdrv_mirror_top_do_write() when not in active 1913 * mode. 1914 */ 1915 bdrv_disable_dirty_bitmap(s->dirty_bitmap); 1916 1917 bdrv_graph_wrlock(bs); 1918 ret = block_job_add_bdrv(&s->common, "source", bs, 0, 1919 BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE | 1920 BLK_PERM_CONSISTENT_READ, 1921 errp); 1922 if (ret < 0) { 1923 bdrv_graph_wrunlock(); 1924 goto fail; 1925 } 1926 1927 /* Required permissions are already taken with blk_new() */ 1928 block_job_add_bdrv(&s->common, "target", target, 0, BLK_PERM_ALL, 1929 &error_abort); 1930 1931 /* In commit_active_start() all intermediate nodes disappear, so 1932 * any jobs in them must be blocked */ 1933 if (target_is_backing) { 1934 BlockDriverState *iter, *filtered_target; 1935 uint64_t iter_shared_perms; 1936 1937 /* 1938 * The topmost node with 1939 * bdrv_skip_filters(filtered_target) == bdrv_skip_filters(target) 1940 */ 1941 filtered_target = bdrv_cow_bs(bdrv_find_overlay(bs, target)); 1942 1943 assert(bdrv_skip_filters(filtered_target) == 1944 bdrv_skip_filters(target)); 1945 1946 /* 1947 * XXX BLK_PERM_WRITE needs to be allowed so we don't block 1948 * ourselves at s->base (if writes are blocked for a node, they are 1949 * also blocked for its backing file). The other options would be a 1950 * second filter driver above s->base (== target). 1951 */ 1952 iter_shared_perms = BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE; 1953 1954 for (iter = bdrv_filter_or_cow_bs(bs); iter != target; 1955 iter = bdrv_filter_or_cow_bs(iter)) 1956 { 1957 if (iter == filtered_target) { 1958 /* 1959 * From here on, all nodes are filters on the base. 1960 * This allows us to share BLK_PERM_CONSISTENT_READ. 1961 */ 1962 iter_shared_perms |= BLK_PERM_CONSISTENT_READ; 1963 } 1964 1965 ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, 1966 iter_shared_perms, errp); 1967 if (ret < 0) { 1968 bdrv_graph_wrunlock(); 1969 goto fail; 1970 } 1971 } 1972 1973 if (bdrv_freeze_backing_chain(mirror_top_bs, target, errp) < 0) { 1974 bdrv_graph_wrunlock(); 1975 goto fail; 1976 } 1977 } 1978 bdrv_graph_wrunlock(); 1979 1980 QTAILQ_INIT(&s->ops_in_flight); 1981 1982 trace_mirror_start(bs, s, opaque); 1983 job_start(&s->common.job); 1984 1985 return &s->common; 1986 1987 fail: 1988 if (s) { 1989 /* Make sure this BDS does not go away until we have completed the graph 1990 * changes below */ 1991 bdrv_ref(mirror_top_bs); 1992 1993 g_free(s->replaces); 1994 blk_unref(s->target); 1995 bs_opaque->job = NULL; 1996 if (s->dirty_bitmap) { 1997 bdrv_release_dirty_bitmap(s->dirty_bitmap); 1998 } 1999 job_early_fail(&s->common.job); 2000 } 2001 2002 bs_opaque->stop = true; 2003 bdrv_drained_begin(bs); 2004 bdrv_graph_wrlock(bs); 2005 assert(mirror_top_bs->backing->bs == bs); 2006 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 2007 &error_abort); 2008 bdrv_replace_node(mirror_top_bs, bs, &error_abort); 2009 bdrv_graph_wrunlock(); 2010 bdrv_drained_end(bs); 2011 2012 bdrv_unref(mirror_top_bs); 2013 2014 return NULL; 2015 } 2016 2017 void mirror_start(const char *job_id, BlockDriverState *bs, 2018 BlockDriverState *target, const char *replaces, 2019 int creation_flags, int64_t speed, 2020 uint32_t granularity, int64_t buf_size, 2021 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, 2022 bool zero_target, 2023 BlockdevOnError on_source_error, 2024 BlockdevOnError on_target_error, 2025 bool unmap, const char *filter_node_name, 2026 MirrorCopyMode copy_mode, Error **errp) 2027 { 2028 bool is_none_mode; 2029 BlockDriverState *base; 2030 2031 GLOBAL_STATE_CODE(); 2032 2033 if ((mode == MIRROR_SYNC_MODE_INCREMENTAL) || 2034 (mode == MIRROR_SYNC_MODE_BITMAP)) { 2035 error_setg(errp, "Sync mode '%s' not supported", 2036 MirrorSyncMode_str(mode)); 2037 return; 2038 } 2039 2040 bdrv_graph_rdlock_main_loop(); 2041 is_none_mode = mode == MIRROR_SYNC_MODE_NONE; 2042 base = mode == MIRROR_SYNC_MODE_TOP ? bdrv_backing_chain_next(bs) : NULL; 2043 bdrv_graph_rdunlock_main_loop(); 2044 2045 mirror_start_job(job_id, bs, creation_flags, target, replaces, 2046 speed, granularity, buf_size, backing_mode, zero_target, 2047 on_source_error, on_target_error, unmap, NULL, NULL, 2048 &mirror_job_driver, is_none_mode, base, false, 2049 filter_node_name, true, copy_mode, errp); 2050 } 2051 2052 BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs, 2053 BlockDriverState *base, int creation_flags, 2054 int64_t speed, BlockdevOnError on_error, 2055 const char *filter_node_name, 2056 BlockCompletionFunc *cb, void *opaque, 2057 bool auto_complete, Error **errp) 2058 { 2059 bool base_read_only; 2060 BlockJob *job; 2061 2062 GLOBAL_STATE_CODE(); 2063 2064 base_read_only = bdrv_is_read_only(base); 2065 2066 if (base_read_only) { 2067 if (bdrv_reopen_set_read_only(base, false, errp) < 0) { 2068 return NULL; 2069 } 2070 } 2071 2072 job = mirror_start_job( 2073 job_id, bs, creation_flags, base, NULL, speed, 0, 0, 2074 MIRROR_LEAVE_BACKING_CHAIN, false, 2075 on_error, on_error, true, cb, opaque, 2076 &commit_active_job_driver, false, base, auto_complete, 2077 filter_node_name, false, MIRROR_COPY_MODE_BACKGROUND, 2078 errp); 2079 if (!job) { 2080 goto error_restore_flags; 2081 } 2082 2083 return job; 2084 2085 error_restore_flags: 2086 /* ignore error and errp for bdrv_reopen, because we want to propagate 2087 * the original error */ 2088 if (base_read_only) { 2089 bdrv_reopen_set_read_only(base, true, NULL); 2090 } 2091 return NULL; 2092 } 2093