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 "trace.h" 16 #include "block/blockjob_int.h" 17 #include "block/block_int.h" 18 #include "sysemu/block-backend.h" 19 #include "qapi/error.h" 20 #include "qapi/qmp/qerror.h" 21 #include "qemu/ratelimit.h" 22 #include "qemu/bitmap.h" 23 24 #define SLICE_TIME 100000000ULL /* ns */ 25 #define MAX_IN_FLIGHT 16 26 #define MAX_IO_SECTORS ((1 << 20) >> BDRV_SECTOR_BITS) /* 1 Mb */ 27 #define DEFAULT_MIRROR_BUF_SIZE \ 28 (MAX_IN_FLIGHT * MAX_IO_SECTORS * BDRV_SECTOR_SIZE) 29 30 /* The mirroring buffer is a list of granularity-sized chunks. 31 * Free chunks are organized in a list. 32 */ 33 typedef struct MirrorBuffer { 34 QSIMPLEQ_ENTRY(MirrorBuffer) next; 35 } MirrorBuffer; 36 37 typedef struct MirrorBlockJob { 38 BlockJob common; 39 RateLimit limit; 40 BlockBackend *target; 41 BlockDriverState *base; 42 /* The name of the graph node to replace */ 43 char *replaces; 44 /* The BDS to replace */ 45 BlockDriverState *to_replace; 46 /* Used to block operations on the drive-mirror-replace target */ 47 Error *replace_blocker; 48 bool is_none_mode; 49 BlockMirrorBackingMode backing_mode; 50 BlockdevOnError on_source_error, on_target_error; 51 bool synced; 52 bool should_complete; 53 int64_t granularity; 54 size_t buf_size; 55 int64_t bdev_length; 56 unsigned long *cow_bitmap; 57 BdrvDirtyBitmap *dirty_bitmap; 58 BdrvDirtyBitmapIter *dbi; 59 uint8_t *buf; 60 QSIMPLEQ_HEAD(, MirrorBuffer) buf_free; 61 int buf_free_count; 62 63 uint64_t last_pause_ns; 64 unsigned long *in_flight_bitmap; 65 int in_flight; 66 int64_t sectors_in_flight; 67 int ret; 68 bool unmap; 69 bool waiting_for_io; 70 int target_cluster_sectors; 71 int max_iov; 72 } MirrorBlockJob; 73 74 typedef struct MirrorOp { 75 MirrorBlockJob *s; 76 QEMUIOVector qiov; 77 int64_t sector_num; 78 int nb_sectors; 79 } MirrorOp; 80 81 static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, 82 int error) 83 { 84 s->synced = false; 85 if (read) { 86 return block_job_error_action(&s->common, s->on_source_error, 87 true, error); 88 } else { 89 return block_job_error_action(&s->common, s->on_target_error, 90 false, error); 91 } 92 } 93 94 static void mirror_iteration_done(MirrorOp *op, int ret) 95 { 96 MirrorBlockJob *s = op->s; 97 struct iovec *iov; 98 int64_t chunk_num; 99 int i, nb_chunks, sectors_per_chunk; 100 101 trace_mirror_iteration_done(s, op->sector_num, op->nb_sectors, ret); 102 103 s->in_flight--; 104 s->sectors_in_flight -= op->nb_sectors; 105 iov = op->qiov.iov; 106 for (i = 0; i < op->qiov.niov; i++) { 107 MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base; 108 QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next); 109 s->buf_free_count++; 110 } 111 112 sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; 113 chunk_num = op->sector_num / sectors_per_chunk; 114 nb_chunks = DIV_ROUND_UP(op->nb_sectors, sectors_per_chunk); 115 bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks); 116 if (ret >= 0) { 117 if (s->cow_bitmap) { 118 bitmap_set(s->cow_bitmap, chunk_num, nb_chunks); 119 } 120 s->common.offset += (uint64_t)op->nb_sectors * BDRV_SECTOR_SIZE; 121 } 122 123 qemu_iovec_destroy(&op->qiov); 124 g_free(op); 125 126 if (s->waiting_for_io) { 127 qemu_coroutine_enter(s->common.co); 128 } 129 } 130 131 static void mirror_write_complete(void *opaque, int ret) 132 { 133 MirrorOp *op = opaque; 134 MirrorBlockJob *s = op->s; 135 if (ret < 0) { 136 BlockErrorAction action; 137 138 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->sector_num, op->nb_sectors); 139 action = mirror_error_action(s, false, -ret); 140 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 141 s->ret = ret; 142 } 143 } 144 mirror_iteration_done(op, ret); 145 } 146 147 static void mirror_read_complete(void *opaque, int ret) 148 { 149 MirrorOp *op = opaque; 150 MirrorBlockJob *s = op->s; 151 if (ret < 0) { 152 BlockErrorAction action; 153 154 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->sector_num, op->nb_sectors); 155 action = mirror_error_action(s, true, -ret); 156 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 157 s->ret = ret; 158 } 159 160 mirror_iteration_done(op, ret); 161 return; 162 } 163 blk_aio_pwritev(s->target, op->sector_num * BDRV_SECTOR_SIZE, &op->qiov, 164 0, mirror_write_complete, op); 165 } 166 167 static inline void mirror_clip_sectors(MirrorBlockJob *s, 168 int64_t sector_num, 169 int *nb_sectors) 170 { 171 *nb_sectors = MIN(*nb_sectors, 172 s->bdev_length / BDRV_SECTOR_SIZE - sector_num); 173 } 174 175 /* Round sector_num and/or nb_sectors to target cluster if COW is needed, and 176 * return the offset of the adjusted tail sector against original. */ 177 static int mirror_cow_align(MirrorBlockJob *s, 178 int64_t *sector_num, 179 int *nb_sectors) 180 { 181 bool need_cow; 182 int ret = 0; 183 int chunk_sectors = s->granularity >> BDRV_SECTOR_BITS; 184 int64_t align_sector_num = *sector_num; 185 int align_nb_sectors = *nb_sectors; 186 int max_sectors = chunk_sectors * s->max_iov; 187 188 need_cow = !test_bit(*sector_num / chunk_sectors, s->cow_bitmap); 189 need_cow |= !test_bit((*sector_num + *nb_sectors - 1) / chunk_sectors, 190 s->cow_bitmap); 191 if (need_cow) { 192 bdrv_round_sectors_to_clusters(blk_bs(s->target), *sector_num, 193 *nb_sectors, &align_sector_num, 194 &align_nb_sectors); 195 } 196 197 if (align_nb_sectors > max_sectors) { 198 align_nb_sectors = max_sectors; 199 if (need_cow) { 200 align_nb_sectors = QEMU_ALIGN_DOWN(align_nb_sectors, 201 s->target_cluster_sectors); 202 } 203 } 204 /* Clipping may result in align_nb_sectors unaligned to chunk boundary, but 205 * that doesn't matter because it's already the end of source image. */ 206 mirror_clip_sectors(s, align_sector_num, &align_nb_sectors); 207 208 ret = align_sector_num + align_nb_sectors - (*sector_num + *nb_sectors); 209 *sector_num = align_sector_num; 210 *nb_sectors = align_nb_sectors; 211 assert(ret >= 0); 212 return ret; 213 } 214 215 static inline void mirror_wait_for_io(MirrorBlockJob *s) 216 { 217 assert(!s->waiting_for_io); 218 s->waiting_for_io = true; 219 qemu_coroutine_yield(); 220 s->waiting_for_io = false; 221 } 222 223 /* Submit async read while handling COW. 224 * Returns: The number of sectors copied after and including sector_num, 225 * excluding any sectors copied prior to sector_num due to alignment. 226 * This will be nb_sectors if no alignment is necessary, or 227 * (new_end - sector_num) if tail is rounded up or down due to 228 * alignment or buffer limit. 229 */ 230 static int mirror_do_read(MirrorBlockJob *s, int64_t sector_num, 231 int nb_sectors) 232 { 233 BlockBackend *source = s->common.blk; 234 int sectors_per_chunk, nb_chunks; 235 int ret; 236 MirrorOp *op; 237 int max_sectors; 238 239 sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; 240 max_sectors = sectors_per_chunk * s->max_iov; 241 242 /* We can only handle as much as buf_size at a time. */ 243 nb_sectors = MIN(s->buf_size >> BDRV_SECTOR_BITS, nb_sectors); 244 nb_sectors = MIN(max_sectors, nb_sectors); 245 assert(nb_sectors); 246 ret = nb_sectors; 247 248 if (s->cow_bitmap) { 249 ret += mirror_cow_align(s, §or_num, &nb_sectors); 250 } 251 assert(nb_sectors << BDRV_SECTOR_BITS <= s->buf_size); 252 /* The sector range must meet granularity because: 253 * 1) Caller passes in aligned values; 254 * 2) mirror_cow_align is used only when target cluster is larger. */ 255 assert(!(sector_num % sectors_per_chunk)); 256 nb_chunks = DIV_ROUND_UP(nb_sectors, sectors_per_chunk); 257 258 while (s->buf_free_count < nb_chunks) { 259 trace_mirror_yield_in_flight(s, sector_num, s->in_flight); 260 mirror_wait_for_io(s); 261 } 262 263 /* Allocate a MirrorOp that is used as an AIO callback. */ 264 op = g_new(MirrorOp, 1); 265 op->s = s; 266 op->sector_num = sector_num; 267 op->nb_sectors = nb_sectors; 268 269 /* Now make a QEMUIOVector taking enough granularity-sized chunks 270 * from s->buf_free. 271 */ 272 qemu_iovec_init(&op->qiov, nb_chunks); 273 while (nb_chunks-- > 0) { 274 MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free); 275 size_t remaining = nb_sectors * BDRV_SECTOR_SIZE - op->qiov.size; 276 277 QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next); 278 s->buf_free_count--; 279 qemu_iovec_add(&op->qiov, buf, MIN(s->granularity, remaining)); 280 } 281 282 /* Copy the dirty cluster. */ 283 s->in_flight++; 284 s->sectors_in_flight += nb_sectors; 285 trace_mirror_one_iteration(s, sector_num, nb_sectors); 286 287 blk_aio_preadv(source, sector_num * BDRV_SECTOR_SIZE, &op->qiov, 0, 288 mirror_read_complete, op); 289 return ret; 290 } 291 292 static void mirror_do_zero_or_discard(MirrorBlockJob *s, 293 int64_t sector_num, 294 int nb_sectors, 295 bool is_discard) 296 { 297 MirrorOp *op; 298 299 /* Allocate a MirrorOp that is used as an AIO callback. The qiov is zeroed 300 * so the freeing in mirror_iteration_done is nop. */ 301 op = g_new0(MirrorOp, 1); 302 op->s = s; 303 op->sector_num = sector_num; 304 op->nb_sectors = nb_sectors; 305 306 s->in_flight++; 307 s->sectors_in_flight += nb_sectors; 308 if (is_discard) { 309 blk_aio_pdiscard(s->target, sector_num << BDRV_SECTOR_BITS, 310 op->nb_sectors << BDRV_SECTOR_BITS, 311 mirror_write_complete, op); 312 } else { 313 blk_aio_pwrite_zeroes(s->target, sector_num * BDRV_SECTOR_SIZE, 314 op->nb_sectors * BDRV_SECTOR_SIZE, 315 s->unmap ? BDRV_REQ_MAY_UNMAP : 0, 316 mirror_write_complete, op); 317 } 318 } 319 320 static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) 321 { 322 BlockDriverState *source = blk_bs(s->common.blk); 323 int64_t sector_num, first_chunk; 324 uint64_t delay_ns = 0; 325 /* At least the first dirty chunk is mirrored in one iteration. */ 326 int nb_chunks = 1; 327 int64_t end = s->bdev_length / BDRV_SECTOR_SIZE; 328 int sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; 329 bool write_zeroes_ok = bdrv_can_write_zeroes_with_unmap(blk_bs(s->target)); 330 int max_io_sectors = MAX((s->buf_size >> BDRV_SECTOR_BITS) / MAX_IN_FLIGHT, 331 MAX_IO_SECTORS); 332 333 sector_num = bdrv_dirty_iter_next(s->dbi); 334 if (sector_num < 0) { 335 bdrv_set_dirty_iter(s->dbi, 0); 336 sector_num = bdrv_dirty_iter_next(s->dbi); 337 trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap)); 338 assert(sector_num >= 0); 339 } 340 341 first_chunk = sector_num / sectors_per_chunk; 342 while (test_bit(first_chunk, s->in_flight_bitmap)) { 343 trace_mirror_yield_in_flight(s, sector_num, s->in_flight); 344 mirror_wait_for_io(s); 345 } 346 347 block_job_pause_point(&s->common); 348 349 /* Find the number of consective dirty chunks following the first dirty 350 * one, and wait for in flight requests in them. */ 351 while (nb_chunks * sectors_per_chunk < (s->buf_size >> BDRV_SECTOR_BITS)) { 352 int64_t next_dirty; 353 int64_t next_sector = sector_num + nb_chunks * sectors_per_chunk; 354 int64_t next_chunk = next_sector / sectors_per_chunk; 355 if (next_sector >= end || 356 !bdrv_get_dirty(source, s->dirty_bitmap, next_sector)) { 357 break; 358 } 359 if (test_bit(next_chunk, s->in_flight_bitmap)) { 360 break; 361 } 362 363 next_dirty = bdrv_dirty_iter_next(s->dbi); 364 if (next_dirty > next_sector || next_dirty < 0) { 365 /* The bitmap iterator's cache is stale, refresh it */ 366 bdrv_set_dirty_iter(s->dbi, next_sector); 367 next_dirty = bdrv_dirty_iter_next(s->dbi); 368 } 369 assert(next_dirty == next_sector); 370 nb_chunks++; 371 } 372 373 /* Clear dirty bits before querying the block status, because 374 * calling bdrv_get_block_status_above could yield - if some blocks are 375 * marked dirty in this window, we need to know. 376 */ 377 bdrv_reset_dirty_bitmap(s->dirty_bitmap, sector_num, 378 nb_chunks * sectors_per_chunk); 379 bitmap_set(s->in_flight_bitmap, sector_num / sectors_per_chunk, nb_chunks); 380 while (nb_chunks > 0 && sector_num < end) { 381 int ret; 382 int io_sectors, io_sectors_acct; 383 BlockDriverState *file; 384 enum MirrorMethod { 385 MIRROR_METHOD_COPY, 386 MIRROR_METHOD_ZERO, 387 MIRROR_METHOD_DISCARD 388 } mirror_method = MIRROR_METHOD_COPY; 389 390 assert(!(sector_num % sectors_per_chunk)); 391 ret = bdrv_get_block_status_above(source, NULL, sector_num, 392 nb_chunks * sectors_per_chunk, 393 &io_sectors, &file); 394 if (ret < 0) { 395 io_sectors = MIN(nb_chunks * sectors_per_chunk, max_io_sectors); 396 } else if (ret & BDRV_BLOCK_DATA) { 397 io_sectors = MIN(io_sectors, max_io_sectors); 398 } 399 400 io_sectors -= io_sectors % sectors_per_chunk; 401 if (io_sectors < sectors_per_chunk) { 402 io_sectors = sectors_per_chunk; 403 } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) { 404 int64_t target_sector_num; 405 int target_nb_sectors; 406 bdrv_round_sectors_to_clusters(blk_bs(s->target), sector_num, 407 io_sectors, &target_sector_num, 408 &target_nb_sectors); 409 if (target_sector_num == sector_num && 410 target_nb_sectors == io_sectors) { 411 mirror_method = ret & BDRV_BLOCK_ZERO ? 412 MIRROR_METHOD_ZERO : 413 MIRROR_METHOD_DISCARD; 414 } 415 } 416 417 while (s->in_flight >= MAX_IN_FLIGHT) { 418 trace_mirror_yield_in_flight(s, sector_num, s->in_flight); 419 mirror_wait_for_io(s); 420 } 421 422 if (s->ret < 0) { 423 return 0; 424 } 425 426 mirror_clip_sectors(s, sector_num, &io_sectors); 427 switch (mirror_method) { 428 case MIRROR_METHOD_COPY: 429 io_sectors = mirror_do_read(s, sector_num, io_sectors); 430 io_sectors_acct = io_sectors; 431 break; 432 case MIRROR_METHOD_ZERO: 433 case MIRROR_METHOD_DISCARD: 434 mirror_do_zero_or_discard(s, sector_num, io_sectors, 435 mirror_method == MIRROR_METHOD_DISCARD); 436 if (write_zeroes_ok) { 437 io_sectors_acct = 0; 438 } else { 439 io_sectors_acct = io_sectors; 440 } 441 break; 442 default: 443 abort(); 444 } 445 assert(io_sectors); 446 sector_num += io_sectors; 447 nb_chunks -= DIV_ROUND_UP(io_sectors, sectors_per_chunk); 448 if (s->common.speed) { 449 delay_ns = ratelimit_calculate_delay(&s->limit, io_sectors_acct); 450 } 451 } 452 return delay_ns; 453 } 454 455 static void mirror_free_init(MirrorBlockJob *s) 456 { 457 int granularity = s->granularity; 458 size_t buf_size = s->buf_size; 459 uint8_t *buf = s->buf; 460 461 assert(s->buf_free_count == 0); 462 QSIMPLEQ_INIT(&s->buf_free); 463 while (buf_size != 0) { 464 MirrorBuffer *cur = (MirrorBuffer *)buf; 465 QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); 466 s->buf_free_count++; 467 buf_size -= granularity; 468 buf += granularity; 469 } 470 } 471 472 /* This is also used for the .pause callback. There is no matching 473 * mirror_resume() because mirror_run() will begin iterating again 474 * when the job is resumed. 475 */ 476 static void mirror_wait_for_all_io(MirrorBlockJob *s) 477 { 478 while (s->in_flight > 0) { 479 mirror_wait_for_io(s); 480 } 481 } 482 483 typedef struct { 484 int ret; 485 } MirrorExitData; 486 487 static void mirror_exit(BlockJob *job, void *opaque) 488 { 489 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 490 MirrorExitData *data = opaque; 491 AioContext *replace_aio_context = NULL; 492 BlockDriverState *src = blk_bs(s->common.blk); 493 BlockDriverState *target_bs = blk_bs(s->target); 494 495 /* Make sure that the source BDS doesn't go away before we called 496 * block_job_completed(). */ 497 bdrv_ref(src); 498 499 if (s->to_replace) { 500 replace_aio_context = bdrv_get_aio_context(s->to_replace); 501 aio_context_acquire(replace_aio_context); 502 } 503 504 if (s->should_complete && data->ret == 0) { 505 BlockDriverState *to_replace = src; 506 if (s->to_replace) { 507 to_replace = s->to_replace; 508 } 509 510 if (bdrv_get_flags(target_bs) != bdrv_get_flags(to_replace)) { 511 bdrv_reopen(target_bs, bdrv_get_flags(to_replace), NULL); 512 } 513 514 /* The mirror job has no requests in flight any more, but we need to 515 * drain potential other users of the BDS before changing the graph. */ 516 bdrv_drained_begin(target_bs); 517 bdrv_replace_in_backing_chain(to_replace, target_bs); 518 bdrv_drained_end(target_bs); 519 520 /* We just changed the BDS the job BB refers to */ 521 blk_remove_bs(job->blk); 522 blk_insert_bs(job->blk, src); 523 } 524 if (s->to_replace) { 525 bdrv_op_unblock_all(s->to_replace, s->replace_blocker); 526 error_free(s->replace_blocker); 527 bdrv_unref(s->to_replace); 528 } 529 if (replace_aio_context) { 530 aio_context_release(replace_aio_context); 531 } 532 g_free(s->replaces); 533 blk_unref(s->target); 534 s->target = NULL; 535 block_job_completed(&s->common, data->ret); 536 g_free(data); 537 bdrv_drained_end(src); 538 bdrv_unref(src); 539 } 540 541 static void mirror_throttle(MirrorBlockJob *s) 542 { 543 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 544 545 if (now - s->last_pause_ns > SLICE_TIME) { 546 s->last_pause_ns = now; 547 block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, 0); 548 } else { 549 block_job_pause_point(&s->common); 550 } 551 } 552 553 static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) 554 { 555 int64_t sector_num, end; 556 BlockDriverState *base = s->base; 557 BlockDriverState *bs = blk_bs(s->common.blk); 558 BlockDriverState *target_bs = blk_bs(s->target); 559 int ret, n; 560 561 end = s->bdev_length / BDRV_SECTOR_SIZE; 562 563 if (base == NULL && !bdrv_has_zero_init(target_bs)) { 564 if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { 565 bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, end); 566 return 0; 567 } 568 569 for (sector_num = 0; sector_num < end; ) { 570 int nb_sectors = MIN(end - sector_num, 571 QEMU_ALIGN_DOWN(INT_MAX, s->granularity) >> BDRV_SECTOR_BITS); 572 573 mirror_throttle(s); 574 575 if (block_job_is_cancelled(&s->common)) { 576 return 0; 577 } 578 579 if (s->in_flight >= MAX_IN_FLIGHT) { 580 trace_mirror_yield(s, s->in_flight, s->buf_free_count, -1); 581 mirror_wait_for_io(s); 582 continue; 583 } 584 585 mirror_do_zero_or_discard(s, sector_num, nb_sectors, false); 586 sector_num += nb_sectors; 587 } 588 589 mirror_wait_for_all_io(s); 590 } 591 592 /* First part, loop on the sectors and initialize the dirty bitmap. */ 593 for (sector_num = 0; sector_num < end; ) { 594 /* Just to make sure we are not exceeding int limit. */ 595 int nb_sectors = MIN(INT_MAX >> BDRV_SECTOR_BITS, 596 end - sector_num); 597 598 mirror_throttle(s); 599 600 if (block_job_is_cancelled(&s->common)) { 601 return 0; 602 } 603 604 ret = bdrv_is_allocated_above(bs, base, sector_num, nb_sectors, &n); 605 if (ret < 0) { 606 return ret; 607 } 608 609 assert(n > 0); 610 if (ret == 1) { 611 bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n); 612 } 613 sector_num += n; 614 } 615 return 0; 616 } 617 618 static void coroutine_fn mirror_run(void *opaque) 619 { 620 MirrorBlockJob *s = opaque; 621 MirrorExitData *data; 622 BlockDriverState *bs = blk_bs(s->common.blk); 623 BlockDriverState *target_bs = blk_bs(s->target); 624 bool need_drain = true; 625 int64_t length; 626 BlockDriverInfo bdi; 627 char backing_filename[2]; /* we only need 2 characters because we are only 628 checking for a NULL string */ 629 int ret = 0; 630 int target_cluster_size = BDRV_SECTOR_SIZE; 631 632 if (block_job_is_cancelled(&s->common)) { 633 goto immediate_exit; 634 } 635 636 s->bdev_length = bdrv_getlength(bs); 637 if (s->bdev_length < 0) { 638 ret = s->bdev_length; 639 goto immediate_exit; 640 } else if (s->bdev_length == 0) { 641 /* Report BLOCK_JOB_READY and wait for complete. */ 642 block_job_event_ready(&s->common); 643 s->synced = true; 644 while (!block_job_is_cancelled(&s->common) && !s->should_complete) { 645 block_job_yield(&s->common); 646 } 647 s->common.cancelled = false; 648 goto immediate_exit; 649 } 650 651 length = DIV_ROUND_UP(s->bdev_length, s->granularity); 652 s->in_flight_bitmap = bitmap_new(length); 653 654 /* If we have no backing file yet in the destination, we cannot let 655 * the destination do COW. Instead, we copy sectors around the 656 * dirty data if needed. We need a bitmap to do that. 657 */ 658 bdrv_get_backing_filename(target_bs, backing_filename, 659 sizeof(backing_filename)); 660 if (!bdrv_get_info(target_bs, &bdi) && bdi.cluster_size) { 661 target_cluster_size = bdi.cluster_size; 662 } 663 if (backing_filename[0] && !target_bs->backing 664 && s->granularity < target_cluster_size) { 665 s->buf_size = MAX(s->buf_size, target_cluster_size); 666 s->cow_bitmap = bitmap_new(length); 667 } 668 s->target_cluster_sectors = target_cluster_size >> BDRV_SECTOR_BITS; 669 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); 670 671 s->buf = qemu_try_blockalign(bs, s->buf_size); 672 if (s->buf == NULL) { 673 ret = -ENOMEM; 674 goto immediate_exit; 675 } 676 677 mirror_free_init(s); 678 679 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 680 if (!s->is_none_mode) { 681 ret = mirror_dirty_init(s); 682 if (ret < 0 || block_job_is_cancelled(&s->common)) { 683 goto immediate_exit; 684 } 685 } 686 687 assert(!s->dbi); 688 s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap, 0); 689 for (;;) { 690 uint64_t delay_ns = 0; 691 int64_t cnt, delta; 692 bool should_complete; 693 694 if (s->ret < 0) { 695 ret = s->ret; 696 goto immediate_exit; 697 } 698 699 block_job_pause_point(&s->common); 700 701 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 702 /* s->common.offset contains the number of bytes already processed so 703 * far, cnt is the number of dirty sectors remaining and 704 * s->sectors_in_flight is the number of sectors currently being 705 * processed; together those are the current total operation length */ 706 s->common.len = s->common.offset + 707 (cnt + s->sectors_in_flight) * BDRV_SECTOR_SIZE; 708 709 /* Note that even when no rate limit is applied we need to yield 710 * periodically with no pending I/O so that bdrv_drain_all() returns. 711 * We do so every SLICE_TIME nanoseconds, or when there is an error, 712 * or when the source is clean, whichever comes first. 713 */ 714 delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns; 715 if (delta < SLICE_TIME && 716 s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { 717 if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || 718 (cnt == 0 && s->in_flight > 0)) { 719 trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt); 720 mirror_wait_for_io(s); 721 continue; 722 } else if (cnt != 0) { 723 delay_ns = mirror_iteration(s); 724 } 725 } 726 727 should_complete = false; 728 if (s->in_flight == 0 && cnt == 0) { 729 trace_mirror_before_flush(s); 730 ret = blk_flush(s->target); 731 if (ret < 0) { 732 if (mirror_error_action(s, false, -ret) == 733 BLOCK_ERROR_ACTION_REPORT) { 734 goto immediate_exit; 735 } 736 } else { 737 /* We're out of the streaming phase. From now on, if the job 738 * is cancelled we will actually complete all pending I/O and 739 * report completion. This way, block-job-cancel will leave 740 * the target in a consistent state. 741 */ 742 if (!s->synced) { 743 block_job_event_ready(&s->common); 744 s->synced = true; 745 } 746 747 should_complete = s->should_complete || 748 block_job_is_cancelled(&s->common); 749 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 750 } 751 } 752 753 if (cnt == 0 && should_complete) { 754 /* The dirty bitmap is not updated while operations are pending. 755 * If we're about to exit, wait for pending operations before 756 * calling bdrv_get_dirty_count(bs), or we may exit while the 757 * source has dirty data to copy! 758 * 759 * Note that I/O can be submitted by the guest while 760 * mirror_populate runs, so pause it now. Before deciding 761 * whether to switch to target check one last time if I/O has 762 * come in the meanwhile, and if not flush the data to disk. 763 */ 764 trace_mirror_before_drain(s, cnt); 765 766 bdrv_drained_begin(bs); 767 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 768 if (cnt > 0) { 769 bdrv_drained_end(bs); 770 continue; 771 } 772 773 /* The two disks are in sync. Exit and report successful 774 * completion. 775 */ 776 assert(QLIST_EMPTY(&bs->tracked_requests)); 777 s->common.cancelled = false; 778 need_drain = false; 779 break; 780 } 781 782 ret = 0; 783 trace_mirror_before_sleep(s, cnt, s->synced, delay_ns); 784 if (!s->synced) { 785 block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); 786 if (block_job_is_cancelled(&s->common)) { 787 break; 788 } 789 } else if (!should_complete) { 790 delay_ns = (s->in_flight == 0 && cnt == 0 ? SLICE_TIME : 0); 791 block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); 792 } 793 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 794 } 795 796 immediate_exit: 797 if (s->in_flight > 0) { 798 /* We get here only if something went wrong. Either the job failed, 799 * or it was cancelled prematurely so that we do not guarantee that 800 * the target is a copy of the source. 801 */ 802 assert(ret < 0 || (!s->synced && block_job_is_cancelled(&s->common))); 803 assert(need_drain); 804 mirror_wait_for_all_io(s); 805 } 806 807 assert(s->in_flight == 0); 808 qemu_vfree(s->buf); 809 g_free(s->cow_bitmap); 810 g_free(s->in_flight_bitmap); 811 bdrv_dirty_iter_free(s->dbi); 812 bdrv_release_dirty_bitmap(bs, s->dirty_bitmap); 813 814 data = g_malloc(sizeof(*data)); 815 data->ret = ret; 816 817 if (need_drain) { 818 bdrv_drained_begin(bs); 819 } 820 block_job_defer_to_main_loop(&s->common, mirror_exit, data); 821 } 822 823 static void mirror_set_speed(BlockJob *job, int64_t speed, Error **errp) 824 { 825 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 826 827 if (speed < 0) { 828 error_setg(errp, QERR_INVALID_PARAMETER, "speed"); 829 return; 830 } 831 ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME); 832 } 833 834 static void mirror_complete(BlockJob *job, Error **errp) 835 { 836 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 837 BlockDriverState *src, *target; 838 839 src = blk_bs(job->blk); 840 target = blk_bs(s->target); 841 842 if (!s->synced) { 843 error_setg(errp, "The active block job '%s' cannot be completed", 844 job->id); 845 return; 846 } 847 848 if (s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { 849 int ret; 850 851 assert(!target->backing); 852 ret = bdrv_open_backing_file(target, NULL, "backing", errp); 853 if (ret < 0) { 854 return; 855 } 856 } 857 858 /* block all operations on to_replace bs */ 859 if (s->replaces) { 860 AioContext *replace_aio_context; 861 862 s->to_replace = bdrv_find_node(s->replaces); 863 if (!s->to_replace) { 864 error_setg(errp, "Node name '%s' not found", s->replaces); 865 return; 866 } 867 868 replace_aio_context = bdrv_get_aio_context(s->to_replace); 869 aio_context_acquire(replace_aio_context); 870 871 error_setg(&s->replace_blocker, 872 "block device is in use by block-job-complete"); 873 bdrv_op_block_all(s->to_replace, s->replace_blocker); 874 bdrv_ref(s->to_replace); 875 876 aio_context_release(replace_aio_context); 877 } 878 879 if (s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { 880 BlockDriverState *backing = s->is_none_mode ? src : s->base; 881 if (backing_bs(target) != backing) { 882 bdrv_set_backing_hd(target, backing); 883 } 884 } 885 886 s->should_complete = true; 887 block_job_enter(&s->common); 888 } 889 890 static void mirror_pause(BlockJob *job) 891 { 892 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 893 894 mirror_wait_for_all_io(s); 895 } 896 897 static void mirror_attached_aio_context(BlockJob *job, AioContext *new_context) 898 { 899 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 900 901 blk_set_aio_context(s->target, new_context); 902 } 903 904 static void mirror_drain(BlockJob *job) 905 { 906 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 907 908 /* Need to keep a reference in case blk_drain triggers execution 909 * of mirror_complete... 910 */ 911 if (s->target) { 912 BlockBackend *target = s->target; 913 blk_ref(target); 914 blk_drain(target); 915 blk_unref(target); 916 } 917 } 918 919 static const BlockJobDriver mirror_job_driver = { 920 .instance_size = sizeof(MirrorBlockJob), 921 .job_type = BLOCK_JOB_TYPE_MIRROR, 922 .set_speed = mirror_set_speed, 923 .complete = mirror_complete, 924 .pause = mirror_pause, 925 .attached_aio_context = mirror_attached_aio_context, 926 .drain = mirror_drain, 927 }; 928 929 static const BlockJobDriver commit_active_job_driver = { 930 .instance_size = sizeof(MirrorBlockJob), 931 .job_type = BLOCK_JOB_TYPE_COMMIT, 932 .set_speed = mirror_set_speed, 933 .complete = mirror_complete, 934 .pause = mirror_pause, 935 .attached_aio_context = mirror_attached_aio_context, 936 .drain = mirror_drain, 937 }; 938 939 static void mirror_start_job(const char *job_id, BlockDriverState *bs, 940 int creation_flags, BlockDriverState *target, 941 const char *replaces, int64_t speed, 942 uint32_t granularity, int64_t buf_size, 943 BlockMirrorBackingMode backing_mode, 944 BlockdevOnError on_source_error, 945 BlockdevOnError on_target_error, 946 bool unmap, 947 BlockCompletionFunc *cb, 948 void *opaque, Error **errp, 949 const BlockJobDriver *driver, 950 bool is_none_mode, BlockDriverState *base, 951 bool auto_complete) 952 { 953 MirrorBlockJob *s; 954 955 if (granularity == 0) { 956 granularity = bdrv_get_default_bitmap_granularity(target); 957 } 958 959 assert ((granularity & (granularity - 1)) == 0); 960 961 if (buf_size < 0) { 962 error_setg(errp, "Invalid parameter 'buf-size'"); 963 return; 964 } 965 966 if (buf_size == 0) { 967 buf_size = DEFAULT_MIRROR_BUF_SIZE; 968 } 969 970 s = block_job_create(job_id, driver, bs, speed, creation_flags, 971 cb, opaque, errp); 972 if (!s) { 973 return; 974 } 975 976 s->target = blk_new(); 977 blk_insert_bs(s->target, target); 978 979 s->replaces = g_strdup(replaces); 980 s->on_source_error = on_source_error; 981 s->on_target_error = on_target_error; 982 s->is_none_mode = is_none_mode; 983 s->backing_mode = backing_mode; 984 s->base = base; 985 s->granularity = granularity; 986 s->buf_size = ROUND_UP(buf_size, granularity); 987 s->unmap = unmap; 988 if (auto_complete) { 989 s->should_complete = true; 990 } 991 992 s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp); 993 if (!s->dirty_bitmap) { 994 g_free(s->replaces); 995 blk_unref(s->target); 996 block_job_unref(&s->common); 997 return; 998 } 999 1000 block_job_add_bdrv(&s->common, target); 1001 /* In commit_active_start() all intermediate nodes disappear, so 1002 * any jobs in them must be blocked */ 1003 if (bdrv_chain_contains(bs, target)) { 1004 BlockDriverState *iter; 1005 for (iter = backing_bs(bs); iter != target; iter = backing_bs(iter)) { 1006 block_job_add_bdrv(&s->common, iter); 1007 } 1008 } 1009 1010 s->common.co = qemu_coroutine_create(mirror_run, s); 1011 trace_mirror_start(bs, s, s->common.co, opaque); 1012 qemu_coroutine_enter(s->common.co); 1013 } 1014 1015 void mirror_start(const char *job_id, BlockDriverState *bs, 1016 BlockDriverState *target, const char *replaces, 1017 int64_t speed, uint32_t granularity, int64_t buf_size, 1018 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, 1019 BlockdevOnError on_source_error, 1020 BlockdevOnError on_target_error, 1021 bool unmap, Error **errp) 1022 { 1023 bool is_none_mode; 1024 BlockDriverState *base; 1025 1026 if (mode == MIRROR_SYNC_MODE_INCREMENTAL) { 1027 error_setg(errp, "Sync mode 'incremental' not supported"); 1028 return; 1029 } 1030 is_none_mode = mode == MIRROR_SYNC_MODE_NONE; 1031 base = mode == MIRROR_SYNC_MODE_TOP ? backing_bs(bs) : NULL; 1032 mirror_start_job(job_id, bs, BLOCK_JOB_DEFAULT, target, replaces, 1033 speed, granularity, buf_size, backing_mode, 1034 on_source_error, on_target_error, unmap, NULL, NULL, errp, 1035 &mirror_job_driver, is_none_mode, base, false); 1036 } 1037 1038 void commit_active_start(const char *job_id, BlockDriverState *bs, 1039 BlockDriverState *base, int creation_flags, 1040 int64_t speed, BlockdevOnError on_error, 1041 BlockCompletionFunc *cb, void *opaque, Error **errp, 1042 bool auto_complete) 1043 { 1044 int64_t length, base_length; 1045 int orig_base_flags; 1046 int ret; 1047 Error *local_err = NULL; 1048 1049 orig_base_flags = bdrv_get_flags(base); 1050 1051 if (bdrv_reopen(base, bs->open_flags, errp)) { 1052 return; 1053 } 1054 1055 length = bdrv_getlength(bs); 1056 if (length < 0) { 1057 error_setg_errno(errp, -length, 1058 "Unable to determine length of %s", bs->filename); 1059 goto error_restore_flags; 1060 } 1061 1062 base_length = bdrv_getlength(base); 1063 if (base_length < 0) { 1064 error_setg_errno(errp, -base_length, 1065 "Unable to determine length of %s", base->filename); 1066 goto error_restore_flags; 1067 } 1068 1069 if (length > base_length) { 1070 ret = bdrv_truncate(base, length); 1071 if (ret < 0) { 1072 error_setg_errno(errp, -ret, 1073 "Top image %s is larger than base image %s, and " 1074 "resize of base image failed", 1075 bs->filename, base->filename); 1076 goto error_restore_flags; 1077 } 1078 } 1079 1080 mirror_start_job(job_id, bs, creation_flags, base, NULL, speed, 0, 0, 1081 MIRROR_LEAVE_BACKING_CHAIN, 1082 on_error, on_error, true, cb, opaque, &local_err, 1083 &commit_active_job_driver, false, base, auto_complete); 1084 if (local_err) { 1085 error_propagate(errp, local_err); 1086 goto error_restore_flags; 1087 } 1088 1089 return; 1090 1091 error_restore_flags: 1092 /* ignore error and errp for bdrv_reopen, because we want to propagate 1093 * the original error */ 1094 bdrv_reopen(base, orig_base_flags, NULL); 1095 return; 1096 } 1097