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.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 HBitmapIter hbi; 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 = hbitmap_iter_next(&s->hbi); 334 if (sector_num < 0) { 335 bdrv_dirty_iter_init(s->dirty_bitmap, &s->hbi); 336 sector_num = hbitmap_iter_next(&s->hbi); 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 hbitmap_next; 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 hbitmap_next = hbitmap_iter_next(&s->hbi); 364 if (hbitmap_next > next_sector || hbitmap_next < 0) { 365 /* The bitmap iterator's cache is stale, refresh it */ 366 bdrv_set_dirty_iter(&s->hbi, next_sector); 367 hbitmap_next = hbitmap_iter_next(&s->hbi); 368 } 369 assert(hbitmap_next == 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 mirror_clip_sectors(s, sector_num, &io_sectors); 423 switch (mirror_method) { 424 case MIRROR_METHOD_COPY: 425 io_sectors = mirror_do_read(s, sector_num, io_sectors); 426 io_sectors_acct = io_sectors; 427 break; 428 case MIRROR_METHOD_ZERO: 429 case MIRROR_METHOD_DISCARD: 430 mirror_do_zero_or_discard(s, sector_num, io_sectors, 431 mirror_method == MIRROR_METHOD_DISCARD); 432 if (write_zeroes_ok) { 433 io_sectors_acct = 0; 434 } else { 435 io_sectors_acct = io_sectors; 436 } 437 break; 438 default: 439 abort(); 440 } 441 assert(io_sectors); 442 sector_num += io_sectors; 443 nb_chunks -= DIV_ROUND_UP(io_sectors, sectors_per_chunk); 444 if (s->common.speed) { 445 delay_ns = ratelimit_calculate_delay(&s->limit, io_sectors_acct); 446 } 447 } 448 return delay_ns; 449 } 450 451 static void mirror_free_init(MirrorBlockJob *s) 452 { 453 int granularity = s->granularity; 454 size_t buf_size = s->buf_size; 455 uint8_t *buf = s->buf; 456 457 assert(s->buf_free_count == 0); 458 QSIMPLEQ_INIT(&s->buf_free); 459 while (buf_size != 0) { 460 MirrorBuffer *cur = (MirrorBuffer *)buf; 461 QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); 462 s->buf_free_count++; 463 buf_size -= granularity; 464 buf += granularity; 465 } 466 } 467 468 static void mirror_drain(MirrorBlockJob *s) 469 { 470 while (s->in_flight > 0) { 471 mirror_wait_for_io(s); 472 } 473 } 474 475 typedef struct { 476 int ret; 477 } MirrorExitData; 478 479 static void mirror_exit(BlockJob *job, void *opaque) 480 { 481 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 482 MirrorExitData *data = opaque; 483 AioContext *replace_aio_context = NULL; 484 BlockDriverState *src = blk_bs(s->common.blk); 485 BlockDriverState *target_bs = blk_bs(s->target); 486 487 /* Make sure that the source BDS doesn't go away before we called 488 * block_job_completed(). */ 489 bdrv_ref(src); 490 491 if (s->to_replace) { 492 replace_aio_context = bdrv_get_aio_context(s->to_replace); 493 aio_context_acquire(replace_aio_context); 494 } 495 496 if (s->should_complete && data->ret == 0) { 497 BlockDriverState *to_replace = src; 498 if (s->to_replace) { 499 to_replace = s->to_replace; 500 } 501 502 if (bdrv_get_flags(target_bs) != bdrv_get_flags(to_replace)) { 503 bdrv_reopen(target_bs, bdrv_get_flags(to_replace), NULL); 504 } 505 506 /* The mirror job has no requests in flight any more, but we need to 507 * drain potential other users of the BDS before changing the graph. */ 508 bdrv_drained_begin(target_bs); 509 bdrv_replace_in_backing_chain(to_replace, target_bs); 510 bdrv_drained_end(target_bs); 511 512 /* We just changed the BDS the job BB refers to */ 513 blk_remove_bs(job->blk); 514 blk_insert_bs(job->blk, src); 515 } 516 if (s->to_replace) { 517 bdrv_op_unblock_all(s->to_replace, s->replace_blocker); 518 error_free(s->replace_blocker); 519 bdrv_unref(s->to_replace); 520 } 521 if (replace_aio_context) { 522 aio_context_release(replace_aio_context); 523 } 524 g_free(s->replaces); 525 bdrv_op_unblock_all(target_bs, s->common.blocker); 526 blk_unref(s->target); 527 block_job_completed(&s->common, data->ret); 528 g_free(data); 529 bdrv_drained_end(src); 530 bdrv_unref(src); 531 } 532 533 static void mirror_throttle(MirrorBlockJob *s) 534 { 535 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 536 537 if (now - s->last_pause_ns > SLICE_TIME) { 538 s->last_pause_ns = now; 539 block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, 0); 540 } else { 541 block_job_pause_point(&s->common); 542 } 543 } 544 545 static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) 546 { 547 int64_t sector_num, end; 548 BlockDriverState *base = s->base; 549 BlockDriverState *bs = blk_bs(s->common.blk); 550 BlockDriverState *target_bs = blk_bs(s->target); 551 int ret, n; 552 553 end = s->bdev_length / BDRV_SECTOR_SIZE; 554 555 if (base == NULL && !bdrv_has_zero_init(target_bs)) { 556 if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { 557 bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, end); 558 return 0; 559 } 560 561 for (sector_num = 0; sector_num < end; ) { 562 int nb_sectors = MIN(end - sector_num, 563 QEMU_ALIGN_DOWN(INT_MAX, s->granularity) >> BDRV_SECTOR_BITS); 564 565 mirror_throttle(s); 566 567 if (block_job_is_cancelled(&s->common)) { 568 return 0; 569 } 570 571 if (s->in_flight >= MAX_IN_FLIGHT) { 572 trace_mirror_yield(s, s->in_flight, s->buf_free_count, -1); 573 mirror_wait_for_io(s); 574 continue; 575 } 576 577 mirror_do_zero_or_discard(s, sector_num, nb_sectors, false); 578 sector_num += nb_sectors; 579 } 580 581 mirror_drain(s); 582 } 583 584 /* First part, loop on the sectors and initialize the dirty bitmap. */ 585 for (sector_num = 0; sector_num < end; ) { 586 /* Just to make sure we are not exceeding int limit. */ 587 int nb_sectors = MIN(INT_MAX >> BDRV_SECTOR_BITS, 588 end - sector_num); 589 590 mirror_throttle(s); 591 592 if (block_job_is_cancelled(&s->common)) { 593 return 0; 594 } 595 596 ret = bdrv_is_allocated_above(bs, base, sector_num, nb_sectors, &n); 597 if (ret < 0) { 598 return ret; 599 } 600 601 assert(n > 0); 602 if (ret == 1) { 603 bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n); 604 } 605 sector_num += n; 606 } 607 return 0; 608 } 609 610 static void coroutine_fn mirror_run(void *opaque) 611 { 612 MirrorBlockJob *s = opaque; 613 MirrorExitData *data; 614 BlockDriverState *bs = blk_bs(s->common.blk); 615 BlockDriverState *target_bs = blk_bs(s->target); 616 int64_t length; 617 BlockDriverInfo bdi; 618 char backing_filename[2]; /* we only need 2 characters because we are only 619 checking for a NULL string */ 620 int ret = 0; 621 int target_cluster_size = BDRV_SECTOR_SIZE; 622 623 if (block_job_is_cancelled(&s->common)) { 624 goto immediate_exit; 625 } 626 627 s->bdev_length = bdrv_getlength(bs); 628 if (s->bdev_length < 0) { 629 ret = s->bdev_length; 630 goto immediate_exit; 631 } else if (s->bdev_length == 0) { 632 /* Report BLOCK_JOB_READY and wait for complete. */ 633 block_job_event_ready(&s->common); 634 s->synced = true; 635 while (!block_job_is_cancelled(&s->common) && !s->should_complete) { 636 block_job_yield(&s->common); 637 } 638 s->common.cancelled = false; 639 goto immediate_exit; 640 } 641 642 length = DIV_ROUND_UP(s->bdev_length, s->granularity); 643 s->in_flight_bitmap = bitmap_new(length); 644 645 /* If we have no backing file yet in the destination, we cannot let 646 * the destination do COW. Instead, we copy sectors around the 647 * dirty data if needed. We need a bitmap to do that. 648 */ 649 bdrv_get_backing_filename(target_bs, backing_filename, 650 sizeof(backing_filename)); 651 if (!bdrv_get_info(target_bs, &bdi) && bdi.cluster_size) { 652 target_cluster_size = bdi.cluster_size; 653 } 654 if (backing_filename[0] && !target_bs->backing 655 && s->granularity < target_cluster_size) { 656 s->buf_size = MAX(s->buf_size, target_cluster_size); 657 s->cow_bitmap = bitmap_new(length); 658 } 659 s->target_cluster_sectors = target_cluster_size >> BDRV_SECTOR_BITS; 660 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); 661 662 s->buf = qemu_try_blockalign(bs, s->buf_size); 663 if (s->buf == NULL) { 664 ret = -ENOMEM; 665 goto immediate_exit; 666 } 667 668 mirror_free_init(s); 669 670 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 671 if (!s->is_none_mode) { 672 ret = mirror_dirty_init(s); 673 if (ret < 0 || block_job_is_cancelled(&s->common)) { 674 goto immediate_exit; 675 } 676 } 677 678 bdrv_dirty_iter_init(s->dirty_bitmap, &s->hbi); 679 for (;;) { 680 uint64_t delay_ns = 0; 681 int64_t cnt, delta; 682 bool should_complete; 683 684 if (s->ret < 0) { 685 ret = s->ret; 686 goto immediate_exit; 687 } 688 689 block_job_pause_point(&s->common); 690 691 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 692 /* s->common.offset contains the number of bytes already processed so 693 * far, cnt is the number of dirty sectors remaining and 694 * s->sectors_in_flight is the number of sectors currently being 695 * processed; together those are the current total operation length */ 696 s->common.len = s->common.offset + 697 (cnt + s->sectors_in_flight) * BDRV_SECTOR_SIZE; 698 699 /* Note that even when no rate limit is applied we need to yield 700 * periodically with no pending I/O so that bdrv_drain_all() returns. 701 * We do so every SLICE_TIME nanoseconds, or when there is an error, 702 * or when the source is clean, whichever comes first. 703 */ 704 delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns; 705 if (delta < SLICE_TIME && 706 s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { 707 if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || 708 (cnt == 0 && s->in_flight > 0)) { 709 trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt); 710 mirror_wait_for_io(s); 711 continue; 712 } else if (cnt != 0) { 713 delay_ns = mirror_iteration(s); 714 } 715 } 716 717 should_complete = false; 718 if (s->in_flight == 0 && cnt == 0) { 719 trace_mirror_before_flush(s); 720 ret = blk_flush(s->target); 721 if (ret < 0) { 722 if (mirror_error_action(s, false, -ret) == 723 BLOCK_ERROR_ACTION_REPORT) { 724 goto immediate_exit; 725 } 726 } else { 727 /* We're out of the streaming phase. From now on, if the job 728 * is cancelled we will actually complete all pending I/O and 729 * report completion. This way, block-job-cancel will leave 730 * the target in a consistent state. 731 */ 732 if (!s->synced) { 733 block_job_event_ready(&s->common); 734 s->synced = true; 735 } 736 737 should_complete = s->should_complete || 738 block_job_is_cancelled(&s->common); 739 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 740 } 741 } 742 743 if (cnt == 0 && should_complete) { 744 /* The dirty bitmap is not updated while operations are pending. 745 * If we're about to exit, wait for pending operations before 746 * calling bdrv_get_dirty_count(bs), or we may exit while the 747 * source has dirty data to copy! 748 * 749 * Note that I/O can be submitted by the guest while 750 * mirror_populate runs. 751 */ 752 trace_mirror_before_drain(s, cnt); 753 bdrv_co_drain(bs); 754 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 755 } 756 757 ret = 0; 758 trace_mirror_before_sleep(s, cnt, s->synced, delay_ns); 759 if (!s->synced) { 760 block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); 761 if (block_job_is_cancelled(&s->common)) { 762 break; 763 } 764 } else if (!should_complete) { 765 delay_ns = (s->in_flight == 0 && cnt == 0 ? SLICE_TIME : 0); 766 block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); 767 } else if (cnt == 0) { 768 /* The two disks are in sync. Exit and report successful 769 * completion. 770 */ 771 assert(QLIST_EMPTY(&bs->tracked_requests)); 772 s->common.cancelled = false; 773 break; 774 } 775 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 776 } 777 778 immediate_exit: 779 if (s->in_flight > 0) { 780 /* We get here only if something went wrong. Either the job failed, 781 * or it was cancelled prematurely so that we do not guarantee that 782 * the target is a copy of the source. 783 */ 784 assert(ret < 0 || (!s->synced && block_job_is_cancelled(&s->common))); 785 mirror_drain(s); 786 } 787 788 assert(s->in_flight == 0); 789 qemu_vfree(s->buf); 790 g_free(s->cow_bitmap); 791 g_free(s->in_flight_bitmap); 792 bdrv_release_dirty_bitmap(bs, s->dirty_bitmap); 793 794 data = g_malloc(sizeof(*data)); 795 data->ret = ret; 796 /* Before we switch to target in mirror_exit, make sure data doesn't 797 * change. */ 798 bdrv_drained_begin(bs); 799 block_job_defer_to_main_loop(&s->common, mirror_exit, data); 800 } 801 802 static void mirror_set_speed(BlockJob *job, int64_t speed, Error **errp) 803 { 804 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 805 806 if (speed < 0) { 807 error_setg(errp, QERR_INVALID_PARAMETER, "speed"); 808 return; 809 } 810 ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME); 811 } 812 813 static void mirror_complete(BlockJob *job, Error **errp) 814 { 815 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 816 BlockDriverState *src, *target; 817 818 src = blk_bs(job->blk); 819 target = blk_bs(s->target); 820 821 if (!s->synced) { 822 error_setg(errp, "The active block job '%s' cannot be completed", 823 job->id); 824 return; 825 } 826 827 if (s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { 828 int ret; 829 830 assert(!target->backing); 831 ret = bdrv_open_backing_file(target, NULL, "backing", errp); 832 if (ret < 0) { 833 return; 834 } 835 } 836 837 /* block all operations on to_replace bs */ 838 if (s->replaces) { 839 AioContext *replace_aio_context; 840 841 s->to_replace = bdrv_find_node(s->replaces); 842 if (!s->to_replace) { 843 error_setg(errp, "Node name '%s' not found", s->replaces); 844 return; 845 } 846 847 replace_aio_context = bdrv_get_aio_context(s->to_replace); 848 aio_context_acquire(replace_aio_context); 849 850 error_setg(&s->replace_blocker, 851 "block device is in use by block-job-complete"); 852 bdrv_op_block_all(s->to_replace, s->replace_blocker); 853 bdrv_ref(s->to_replace); 854 855 aio_context_release(replace_aio_context); 856 } 857 858 if (s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { 859 BlockDriverState *backing = s->is_none_mode ? src : s->base; 860 if (backing_bs(target) != backing) { 861 bdrv_set_backing_hd(target, backing); 862 } 863 } 864 865 s->should_complete = true; 866 block_job_enter(&s->common); 867 } 868 869 /* There is no matching mirror_resume() because mirror_run() will begin 870 * iterating again when the job is resumed. 871 */ 872 static void coroutine_fn mirror_pause(BlockJob *job) 873 { 874 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 875 876 mirror_drain(s); 877 } 878 879 static void mirror_attached_aio_context(BlockJob *job, AioContext *new_context) 880 { 881 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 882 883 blk_set_aio_context(s->target, new_context); 884 } 885 886 static const BlockJobDriver mirror_job_driver = { 887 .instance_size = sizeof(MirrorBlockJob), 888 .job_type = BLOCK_JOB_TYPE_MIRROR, 889 .set_speed = mirror_set_speed, 890 .complete = mirror_complete, 891 .pause = mirror_pause, 892 .attached_aio_context = mirror_attached_aio_context, 893 }; 894 895 static const BlockJobDriver commit_active_job_driver = { 896 .instance_size = sizeof(MirrorBlockJob), 897 .job_type = BLOCK_JOB_TYPE_COMMIT, 898 .set_speed = mirror_set_speed, 899 .complete = mirror_complete, 900 .pause = mirror_pause, 901 .attached_aio_context = mirror_attached_aio_context, 902 }; 903 904 static void mirror_start_job(const char *job_id, BlockDriverState *bs, 905 BlockDriverState *target, const char *replaces, 906 int64_t speed, uint32_t granularity, 907 int64_t buf_size, 908 BlockMirrorBackingMode backing_mode, 909 BlockdevOnError on_source_error, 910 BlockdevOnError on_target_error, 911 bool unmap, 912 BlockCompletionFunc *cb, 913 void *opaque, Error **errp, 914 const BlockJobDriver *driver, 915 bool is_none_mode, BlockDriverState *base) 916 { 917 MirrorBlockJob *s; 918 919 if (granularity == 0) { 920 granularity = bdrv_get_default_bitmap_granularity(target); 921 } 922 923 assert ((granularity & (granularity - 1)) == 0); 924 925 if (buf_size < 0) { 926 error_setg(errp, "Invalid parameter 'buf-size'"); 927 return; 928 } 929 930 if (buf_size == 0) { 931 buf_size = DEFAULT_MIRROR_BUF_SIZE; 932 } 933 934 s = block_job_create(job_id, driver, bs, speed, cb, opaque, errp); 935 if (!s) { 936 return; 937 } 938 939 s->target = blk_new(); 940 blk_insert_bs(s->target, target); 941 942 s->replaces = g_strdup(replaces); 943 s->on_source_error = on_source_error; 944 s->on_target_error = on_target_error; 945 s->is_none_mode = is_none_mode; 946 s->backing_mode = backing_mode; 947 s->base = base; 948 s->granularity = granularity; 949 s->buf_size = ROUND_UP(buf_size, granularity); 950 s->unmap = unmap; 951 952 s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp); 953 if (!s->dirty_bitmap) { 954 g_free(s->replaces); 955 blk_unref(s->target); 956 block_job_unref(&s->common); 957 return; 958 } 959 960 bdrv_op_block_all(target, s->common.blocker); 961 962 s->common.co = qemu_coroutine_create(mirror_run, s); 963 trace_mirror_start(bs, s, s->common.co, opaque); 964 qemu_coroutine_enter(s->common.co); 965 } 966 967 void mirror_start(const char *job_id, BlockDriverState *bs, 968 BlockDriverState *target, const char *replaces, 969 int64_t speed, uint32_t granularity, int64_t buf_size, 970 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, 971 BlockdevOnError on_source_error, 972 BlockdevOnError on_target_error, 973 bool unmap, 974 BlockCompletionFunc *cb, 975 void *opaque, Error **errp) 976 { 977 bool is_none_mode; 978 BlockDriverState *base; 979 980 if (mode == MIRROR_SYNC_MODE_INCREMENTAL) { 981 error_setg(errp, "Sync mode 'incremental' not supported"); 982 return; 983 } 984 is_none_mode = mode == MIRROR_SYNC_MODE_NONE; 985 base = mode == MIRROR_SYNC_MODE_TOP ? backing_bs(bs) : NULL; 986 mirror_start_job(job_id, bs, target, replaces, 987 speed, granularity, buf_size, backing_mode, 988 on_source_error, on_target_error, unmap, cb, opaque, errp, 989 &mirror_job_driver, is_none_mode, base); 990 } 991 992 void commit_active_start(const char *job_id, BlockDriverState *bs, 993 BlockDriverState *base, int64_t speed, 994 BlockdevOnError on_error, 995 BlockCompletionFunc *cb, 996 void *opaque, Error **errp) 997 { 998 int64_t length, base_length; 999 int orig_base_flags; 1000 int ret; 1001 Error *local_err = NULL; 1002 1003 orig_base_flags = bdrv_get_flags(base); 1004 1005 if (bdrv_reopen(base, bs->open_flags, errp)) { 1006 return; 1007 } 1008 1009 length = bdrv_getlength(bs); 1010 if (length < 0) { 1011 error_setg_errno(errp, -length, 1012 "Unable to determine length of %s", bs->filename); 1013 goto error_restore_flags; 1014 } 1015 1016 base_length = bdrv_getlength(base); 1017 if (base_length < 0) { 1018 error_setg_errno(errp, -base_length, 1019 "Unable to determine length of %s", base->filename); 1020 goto error_restore_flags; 1021 } 1022 1023 if (length > base_length) { 1024 ret = bdrv_truncate(base, length); 1025 if (ret < 0) { 1026 error_setg_errno(errp, -ret, 1027 "Top image %s is larger than base image %s, and " 1028 "resize of base image failed", 1029 bs->filename, base->filename); 1030 goto error_restore_flags; 1031 } 1032 } 1033 1034 mirror_start_job(job_id, bs, base, NULL, speed, 0, 0, 1035 MIRROR_LEAVE_BACKING_CHAIN, 1036 on_error, on_error, false, cb, opaque, &local_err, 1037 &commit_active_job_driver, false, base); 1038 if (local_err) { 1039 error_propagate(errp, local_err); 1040 goto error_restore_flags; 1041 } 1042 1043 return; 1044 1045 error_restore_flags: 1046 /* ignore error and errp for bdrv_reopen, because we want to propagate 1047 * the original error */ 1048 bdrv_reopen(base, orig_base_flags, NULL); 1049 return; 1050 } 1051