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 bool initial_zeroing_ongoing; 73 } MirrorBlockJob; 74 75 typedef struct MirrorOp { 76 MirrorBlockJob *s; 77 QEMUIOVector qiov; 78 int64_t sector_num; 79 int nb_sectors; 80 } MirrorOp; 81 82 static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, 83 int error) 84 { 85 s->synced = false; 86 if (read) { 87 return block_job_error_action(&s->common, s->on_source_error, 88 true, error); 89 } else { 90 return block_job_error_action(&s->common, s->on_target_error, 91 false, error); 92 } 93 } 94 95 static void mirror_iteration_done(MirrorOp *op, int ret) 96 { 97 MirrorBlockJob *s = op->s; 98 struct iovec *iov; 99 int64_t chunk_num; 100 int i, nb_chunks, sectors_per_chunk; 101 102 trace_mirror_iteration_done(s, op->sector_num, op->nb_sectors, ret); 103 104 s->in_flight--; 105 s->sectors_in_flight -= op->nb_sectors; 106 iov = op->qiov.iov; 107 for (i = 0; i < op->qiov.niov; i++) { 108 MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base; 109 QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next); 110 s->buf_free_count++; 111 } 112 113 sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; 114 chunk_num = op->sector_num / sectors_per_chunk; 115 nb_chunks = DIV_ROUND_UP(op->nb_sectors, sectors_per_chunk); 116 bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks); 117 if (ret >= 0) { 118 if (s->cow_bitmap) { 119 bitmap_set(s->cow_bitmap, chunk_num, nb_chunks); 120 } 121 if (!s->initial_zeroing_ongoing) { 122 s->common.offset += (uint64_t)op->nb_sectors * BDRV_SECTOR_SIZE; 123 } 124 } 125 qemu_iovec_destroy(&op->qiov); 126 g_free(op); 127 128 if (s->waiting_for_io) { 129 qemu_coroutine_enter(s->common.co); 130 } 131 } 132 133 static void mirror_write_complete(void *opaque, int ret) 134 { 135 MirrorOp *op = opaque; 136 MirrorBlockJob *s = op->s; 137 138 aio_context_acquire(blk_get_aio_context(s->common.blk)); 139 if (ret < 0) { 140 BlockErrorAction action; 141 142 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->sector_num, op->nb_sectors); 143 action = mirror_error_action(s, false, -ret); 144 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 145 s->ret = ret; 146 } 147 } 148 mirror_iteration_done(op, ret); 149 aio_context_release(blk_get_aio_context(s->common.blk)); 150 } 151 152 static void mirror_read_complete(void *opaque, int ret) 153 { 154 MirrorOp *op = opaque; 155 MirrorBlockJob *s = op->s; 156 157 aio_context_acquire(blk_get_aio_context(s->common.blk)); 158 if (ret < 0) { 159 BlockErrorAction action; 160 161 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->sector_num, op->nb_sectors); 162 action = mirror_error_action(s, true, -ret); 163 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 164 s->ret = ret; 165 } 166 167 mirror_iteration_done(op, ret); 168 } else { 169 blk_aio_pwritev(s->target, op->sector_num * BDRV_SECTOR_SIZE, &op->qiov, 170 0, mirror_write_complete, op); 171 } 172 aio_context_release(blk_get_aio_context(s->common.blk)); 173 } 174 175 static inline void mirror_clip_sectors(MirrorBlockJob *s, 176 int64_t sector_num, 177 int *nb_sectors) 178 { 179 *nb_sectors = MIN(*nb_sectors, 180 s->bdev_length / BDRV_SECTOR_SIZE - sector_num); 181 } 182 183 /* Round sector_num and/or nb_sectors to target cluster if COW is needed, and 184 * return the offset of the adjusted tail sector against original. */ 185 static int mirror_cow_align(MirrorBlockJob *s, 186 int64_t *sector_num, 187 int *nb_sectors) 188 { 189 bool need_cow; 190 int ret = 0; 191 int chunk_sectors = s->granularity >> BDRV_SECTOR_BITS; 192 int64_t align_sector_num = *sector_num; 193 int align_nb_sectors = *nb_sectors; 194 int max_sectors = chunk_sectors * s->max_iov; 195 196 need_cow = !test_bit(*sector_num / chunk_sectors, s->cow_bitmap); 197 need_cow |= !test_bit((*sector_num + *nb_sectors - 1) / chunk_sectors, 198 s->cow_bitmap); 199 if (need_cow) { 200 bdrv_round_sectors_to_clusters(blk_bs(s->target), *sector_num, 201 *nb_sectors, &align_sector_num, 202 &align_nb_sectors); 203 } 204 205 if (align_nb_sectors > max_sectors) { 206 align_nb_sectors = max_sectors; 207 if (need_cow) { 208 align_nb_sectors = QEMU_ALIGN_DOWN(align_nb_sectors, 209 s->target_cluster_sectors); 210 } 211 } 212 /* Clipping may result in align_nb_sectors unaligned to chunk boundary, but 213 * that doesn't matter because it's already the end of source image. */ 214 mirror_clip_sectors(s, align_sector_num, &align_nb_sectors); 215 216 ret = align_sector_num + align_nb_sectors - (*sector_num + *nb_sectors); 217 *sector_num = align_sector_num; 218 *nb_sectors = align_nb_sectors; 219 assert(ret >= 0); 220 return ret; 221 } 222 223 static inline void mirror_wait_for_io(MirrorBlockJob *s) 224 { 225 assert(!s->waiting_for_io); 226 s->waiting_for_io = true; 227 qemu_coroutine_yield(); 228 s->waiting_for_io = false; 229 } 230 231 /* Submit async read while handling COW. 232 * Returns: The number of sectors copied after and including sector_num, 233 * excluding any sectors copied prior to sector_num due to alignment. 234 * This will be nb_sectors if no alignment is necessary, or 235 * (new_end - sector_num) if tail is rounded up or down due to 236 * alignment or buffer limit. 237 */ 238 static int mirror_do_read(MirrorBlockJob *s, int64_t sector_num, 239 int nb_sectors) 240 { 241 BlockBackend *source = s->common.blk; 242 int sectors_per_chunk, nb_chunks; 243 int ret; 244 MirrorOp *op; 245 int max_sectors; 246 247 sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; 248 max_sectors = sectors_per_chunk * s->max_iov; 249 250 /* We can only handle as much as buf_size at a time. */ 251 nb_sectors = MIN(s->buf_size >> BDRV_SECTOR_BITS, nb_sectors); 252 nb_sectors = MIN(max_sectors, nb_sectors); 253 assert(nb_sectors); 254 ret = nb_sectors; 255 256 if (s->cow_bitmap) { 257 ret += mirror_cow_align(s, §or_num, &nb_sectors); 258 } 259 assert(nb_sectors << BDRV_SECTOR_BITS <= s->buf_size); 260 /* The sector range must meet granularity because: 261 * 1) Caller passes in aligned values; 262 * 2) mirror_cow_align is used only when target cluster is larger. */ 263 assert(!(sector_num % sectors_per_chunk)); 264 nb_chunks = DIV_ROUND_UP(nb_sectors, sectors_per_chunk); 265 266 while (s->buf_free_count < nb_chunks) { 267 trace_mirror_yield_in_flight(s, sector_num, s->in_flight); 268 mirror_wait_for_io(s); 269 } 270 271 /* Allocate a MirrorOp that is used as an AIO callback. */ 272 op = g_new(MirrorOp, 1); 273 op->s = s; 274 op->sector_num = sector_num; 275 op->nb_sectors = nb_sectors; 276 277 /* Now make a QEMUIOVector taking enough granularity-sized chunks 278 * from s->buf_free. 279 */ 280 qemu_iovec_init(&op->qiov, nb_chunks); 281 while (nb_chunks-- > 0) { 282 MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free); 283 size_t remaining = nb_sectors * BDRV_SECTOR_SIZE - op->qiov.size; 284 285 QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next); 286 s->buf_free_count--; 287 qemu_iovec_add(&op->qiov, buf, MIN(s->granularity, remaining)); 288 } 289 290 /* Copy the dirty cluster. */ 291 s->in_flight++; 292 s->sectors_in_flight += nb_sectors; 293 trace_mirror_one_iteration(s, sector_num, nb_sectors); 294 295 blk_aio_preadv(source, sector_num * BDRV_SECTOR_SIZE, &op->qiov, 0, 296 mirror_read_complete, op); 297 return ret; 298 } 299 300 static void mirror_do_zero_or_discard(MirrorBlockJob *s, 301 int64_t sector_num, 302 int nb_sectors, 303 bool is_discard) 304 { 305 MirrorOp *op; 306 307 /* Allocate a MirrorOp that is used as an AIO callback. The qiov is zeroed 308 * so the freeing in mirror_iteration_done is nop. */ 309 op = g_new0(MirrorOp, 1); 310 op->s = s; 311 op->sector_num = sector_num; 312 op->nb_sectors = nb_sectors; 313 314 s->in_flight++; 315 s->sectors_in_flight += nb_sectors; 316 if (is_discard) { 317 blk_aio_pdiscard(s->target, sector_num << BDRV_SECTOR_BITS, 318 op->nb_sectors << BDRV_SECTOR_BITS, 319 mirror_write_complete, op); 320 } else { 321 blk_aio_pwrite_zeroes(s->target, sector_num * BDRV_SECTOR_SIZE, 322 op->nb_sectors * BDRV_SECTOR_SIZE, 323 s->unmap ? BDRV_REQ_MAY_UNMAP : 0, 324 mirror_write_complete, op); 325 } 326 } 327 328 static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) 329 { 330 BlockDriverState *source = blk_bs(s->common.blk); 331 int64_t sector_num, first_chunk; 332 uint64_t delay_ns = 0; 333 /* At least the first dirty chunk is mirrored in one iteration. */ 334 int nb_chunks = 1; 335 int64_t end = s->bdev_length / BDRV_SECTOR_SIZE; 336 int sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; 337 bool write_zeroes_ok = bdrv_can_write_zeroes_with_unmap(blk_bs(s->target)); 338 int max_io_sectors = MAX((s->buf_size >> BDRV_SECTOR_BITS) / MAX_IN_FLIGHT, 339 MAX_IO_SECTORS); 340 341 sector_num = bdrv_dirty_iter_next(s->dbi); 342 if (sector_num < 0) { 343 bdrv_set_dirty_iter(s->dbi, 0); 344 sector_num = bdrv_dirty_iter_next(s->dbi); 345 trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap)); 346 assert(sector_num >= 0); 347 } 348 349 first_chunk = sector_num / sectors_per_chunk; 350 while (test_bit(first_chunk, s->in_flight_bitmap)) { 351 trace_mirror_yield_in_flight(s, sector_num, s->in_flight); 352 mirror_wait_for_io(s); 353 } 354 355 block_job_pause_point(&s->common); 356 357 /* Find the number of consective dirty chunks following the first dirty 358 * one, and wait for in flight requests in them. */ 359 while (nb_chunks * sectors_per_chunk < (s->buf_size >> BDRV_SECTOR_BITS)) { 360 int64_t next_dirty; 361 int64_t next_sector = sector_num + nb_chunks * sectors_per_chunk; 362 int64_t next_chunk = next_sector / sectors_per_chunk; 363 if (next_sector >= end || 364 !bdrv_get_dirty(source, s->dirty_bitmap, next_sector)) { 365 break; 366 } 367 if (test_bit(next_chunk, s->in_flight_bitmap)) { 368 break; 369 } 370 371 next_dirty = bdrv_dirty_iter_next(s->dbi); 372 if (next_dirty > next_sector || next_dirty < 0) { 373 /* The bitmap iterator's cache is stale, refresh it */ 374 bdrv_set_dirty_iter(s->dbi, next_sector); 375 next_dirty = bdrv_dirty_iter_next(s->dbi); 376 } 377 assert(next_dirty == next_sector); 378 nb_chunks++; 379 } 380 381 /* Clear dirty bits before querying the block status, because 382 * calling bdrv_get_block_status_above could yield - if some blocks are 383 * marked dirty in this window, we need to know. 384 */ 385 bdrv_reset_dirty_bitmap(s->dirty_bitmap, sector_num, 386 nb_chunks * sectors_per_chunk); 387 bitmap_set(s->in_flight_bitmap, sector_num / sectors_per_chunk, nb_chunks); 388 while (nb_chunks > 0 && sector_num < end) { 389 int ret; 390 int io_sectors, io_sectors_acct; 391 BlockDriverState *file; 392 enum MirrorMethod { 393 MIRROR_METHOD_COPY, 394 MIRROR_METHOD_ZERO, 395 MIRROR_METHOD_DISCARD 396 } mirror_method = MIRROR_METHOD_COPY; 397 398 assert(!(sector_num % sectors_per_chunk)); 399 ret = bdrv_get_block_status_above(source, NULL, sector_num, 400 nb_chunks * sectors_per_chunk, 401 &io_sectors, &file); 402 if (ret < 0) { 403 io_sectors = MIN(nb_chunks * sectors_per_chunk, max_io_sectors); 404 } else if (ret & BDRV_BLOCK_DATA) { 405 io_sectors = MIN(io_sectors, max_io_sectors); 406 } 407 408 io_sectors -= io_sectors % sectors_per_chunk; 409 if (io_sectors < sectors_per_chunk) { 410 io_sectors = sectors_per_chunk; 411 } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) { 412 int64_t target_sector_num; 413 int target_nb_sectors; 414 bdrv_round_sectors_to_clusters(blk_bs(s->target), sector_num, 415 io_sectors, &target_sector_num, 416 &target_nb_sectors); 417 if (target_sector_num == sector_num && 418 target_nb_sectors == io_sectors) { 419 mirror_method = ret & BDRV_BLOCK_ZERO ? 420 MIRROR_METHOD_ZERO : 421 MIRROR_METHOD_DISCARD; 422 } 423 } 424 425 while (s->in_flight >= MAX_IN_FLIGHT) { 426 trace_mirror_yield_in_flight(s, sector_num, s->in_flight); 427 mirror_wait_for_io(s); 428 } 429 430 if (s->ret < 0) { 431 return 0; 432 } 433 434 mirror_clip_sectors(s, sector_num, &io_sectors); 435 switch (mirror_method) { 436 case MIRROR_METHOD_COPY: 437 io_sectors = mirror_do_read(s, sector_num, io_sectors); 438 io_sectors_acct = io_sectors; 439 break; 440 case MIRROR_METHOD_ZERO: 441 case MIRROR_METHOD_DISCARD: 442 mirror_do_zero_or_discard(s, sector_num, io_sectors, 443 mirror_method == MIRROR_METHOD_DISCARD); 444 if (write_zeroes_ok) { 445 io_sectors_acct = 0; 446 } else { 447 io_sectors_acct = io_sectors; 448 } 449 break; 450 default: 451 abort(); 452 } 453 assert(io_sectors); 454 sector_num += io_sectors; 455 nb_chunks -= DIV_ROUND_UP(io_sectors, sectors_per_chunk); 456 if (s->common.speed) { 457 delay_ns = ratelimit_calculate_delay(&s->limit, io_sectors_acct); 458 } 459 } 460 return delay_ns; 461 } 462 463 static void mirror_free_init(MirrorBlockJob *s) 464 { 465 int granularity = s->granularity; 466 size_t buf_size = s->buf_size; 467 uint8_t *buf = s->buf; 468 469 assert(s->buf_free_count == 0); 470 QSIMPLEQ_INIT(&s->buf_free); 471 while (buf_size != 0) { 472 MirrorBuffer *cur = (MirrorBuffer *)buf; 473 QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); 474 s->buf_free_count++; 475 buf_size -= granularity; 476 buf += granularity; 477 } 478 } 479 480 /* This is also used for the .pause callback. There is no matching 481 * mirror_resume() because mirror_run() will begin iterating again 482 * when the job is resumed. 483 */ 484 static void mirror_wait_for_all_io(MirrorBlockJob *s) 485 { 486 while (s->in_flight > 0) { 487 mirror_wait_for_io(s); 488 } 489 } 490 491 typedef struct { 492 int ret; 493 } MirrorExitData; 494 495 static void mirror_exit(BlockJob *job, void *opaque) 496 { 497 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 498 MirrorExitData *data = opaque; 499 AioContext *replace_aio_context = NULL; 500 BlockDriverState *src = blk_bs(s->common.blk); 501 BlockDriverState *target_bs = blk_bs(s->target); 502 503 /* Make sure that the source BDS doesn't go away before we called 504 * block_job_completed(). */ 505 bdrv_ref(src); 506 507 if (s->to_replace) { 508 replace_aio_context = bdrv_get_aio_context(s->to_replace); 509 aio_context_acquire(replace_aio_context); 510 } 511 512 if (s->should_complete && data->ret == 0) { 513 BlockDriverState *to_replace = src; 514 if (s->to_replace) { 515 to_replace = s->to_replace; 516 } 517 518 if (bdrv_get_flags(target_bs) != bdrv_get_flags(to_replace)) { 519 bdrv_reopen(target_bs, bdrv_get_flags(to_replace), NULL); 520 } 521 522 /* The mirror job has no requests in flight any more, but we need to 523 * drain potential other users of the BDS before changing the graph. */ 524 bdrv_drained_begin(target_bs); 525 bdrv_replace_in_backing_chain(to_replace, target_bs); 526 bdrv_drained_end(target_bs); 527 528 /* We just changed the BDS the job BB refers to */ 529 blk_remove_bs(job->blk); 530 blk_insert_bs(job->blk, src); 531 } 532 if (s->to_replace) { 533 bdrv_op_unblock_all(s->to_replace, s->replace_blocker); 534 error_free(s->replace_blocker); 535 bdrv_unref(s->to_replace); 536 } 537 if (replace_aio_context) { 538 aio_context_release(replace_aio_context); 539 } 540 g_free(s->replaces); 541 blk_unref(s->target); 542 s->target = NULL; 543 block_job_completed(&s->common, data->ret); 544 g_free(data); 545 bdrv_drained_end(src); 546 bdrv_unref(src); 547 } 548 549 static void mirror_throttle(MirrorBlockJob *s) 550 { 551 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 552 553 if (now - s->last_pause_ns > SLICE_TIME) { 554 s->last_pause_ns = now; 555 block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, 0); 556 } else { 557 block_job_pause_point(&s->common); 558 } 559 } 560 561 static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) 562 { 563 int64_t sector_num, end; 564 BlockDriverState *base = s->base; 565 BlockDriverState *bs = blk_bs(s->common.blk); 566 BlockDriverState *target_bs = blk_bs(s->target); 567 int ret, n; 568 569 end = s->bdev_length / BDRV_SECTOR_SIZE; 570 571 if (base == NULL && !bdrv_has_zero_init(target_bs)) { 572 if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { 573 bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, end); 574 return 0; 575 } 576 577 s->initial_zeroing_ongoing = true; 578 for (sector_num = 0; sector_num < end; ) { 579 int nb_sectors = MIN(end - sector_num, 580 QEMU_ALIGN_DOWN(INT_MAX, s->granularity) >> BDRV_SECTOR_BITS); 581 582 mirror_throttle(s); 583 584 if (block_job_is_cancelled(&s->common)) { 585 s->initial_zeroing_ongoing = false; 586 return 0; 587 } 588 589 if (s->in_flight >= MAX_IN_FLIGHT) { 590 trace_mirror_yield(s, s->in_flight, s->buf_free_count, -1); 591 mirror_wait_for_io(s); 592 continue; 593 } 594 595 mirror_do_zero_or_discard(s, sector_num, nb_sectors, false); 596 sector_num += nb_sectors; 597 } 598 599 mirror_wait_for_all_io(s); 600 s->initial_zeroing_ongoing = false; 601 } 602 603 /* First part, loop on the sectors and initialize the dirty bitmap. */ 604 for (sector_num = 0; sector_num < end; ) { 605 /* Just to make sure we are not exceeding int limit. */ 606 int nb_sectors = MIN(INT_MAX >> BDRV_SECTOR_BITS, 607 end - sector_num); 608 609 mirror_throttle(s); 610 611 if (block_job_is_cancelled(&s->common)) { 612 return 0; 613 } 614 615 ret = bdrv_is_allocated_above(bs, base, sector_num, nb_sectors, &n); 616 if (ret < 0) { 617 return ret; 618 } 619 620 assert(n > 0); 621 if (ret == 1) { 622 bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n); 623 } 624 sector_num += n; 625 } 626 return 0; 627 } 628 629 /* Called when going out of the streaming phase to flush the bulk of the 630 * data to the medium, or just before completing. 631 */ 632 static int mirror_flush(MirrorBlockJob *s) 633 { 634 int ret = blk_flush(s->target); 635 if (ret < 0) { 636 if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) { 637 s->ret = ret; 638 } 639 } 640 return ret; 641 } 642 643 static void coroutine_fn mirror_run(void *opaque) 644 { 645 MirrorBlockJob *s = opaque; 646 MirrorExitData *data; 647 BlockDriverState *bs = blk_bs(s->common.blk); 648 BlockDriverState *target_bs = blk_bs(s->target); 649 bool need_drain = true; 650 int64_t length; 651 BlockDriverInfo bdi; 652 char backing_filename[2]; /* we only need 2 characters because we are only 653 checking for a NULL string */ 654 int ret = 0; 655 int target_cluster_size = BDRV_SECTOR_SIZE; 656 657 if (block_job_is_cancelled(&s->common)) { 658 goto immediate_exit; 659 } 660 661 s->bdev_length = bdrv_getlength(bs); 662 if (s->bdev_length < 0) { 663 ret = s->bdev_length; 664 goto immediate_exit; 665 } else if (s->bdev_length == 0) { 666 /* Report BLOCK_JOB_READY and wait for complete. */ 667 block_job_event_ready(&s->common); 668 s->synced = true; 669 while (!block_job_is_cancelled(&s->common) && !s->should_complete) { 670 block_job_yield(&s->common); 671 } 672 s->common.cancelled = false; 673 goto immediate_exit; 674 } 675 676 length = DIV_ROUND_UP(s->bdev_length, s->granularity); 677 s->in_flight_bitmap = bitmap_new(length); 678 679 /* If we have no backing file yet in the destination, we cannot let 680 * the destination do COW. Instead, we copy sectors around the 681 * dirty data if needed. We need a bitmap to do that. 682 */ 683 bdrv_get_backing_filename(target_bs, backing_filename, 684 sizeof(backing_filename)); 685 if (!bdrv_get_info(target_bs, &bdi) && bdi.cluster_size) { 686 target_cluster_size = bdi.cluster_size; 687 } 688 if (backing_filename[0] && !target_bs->backing 689 && s->granularity < target_cluster_size) { 690 s->buf_size = MAX(s->buf_size, target_cluster_size); 691 s->cow_bitmap = bitmap_new(length); 692 } 693 s->target_cluster_sectors = target_cluster_size >> BDRV_SECTOR_BITS; 694 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); 695 696 s->buf = qemu_try_blockalign(bs, s->buf_size); 697 if (s->buf == NULL) { 698 ret = -ENOMEM; 699 goto immediate_exit; 700 } 701 702 mirror_free_init(s); 703 704 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 705 if (!s->is_none_mode) { 706 ret = mirror_dirty_init(s); 707 if (ret < 0 || block_job_is_cancelled(&s->common)) { 708 goto immediate_exit; 709 } 710 } 711 712 assert(!s->dbi); 713 s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap, 0); 714 for (;;) { 715 uint64_t delay_ns = 0; 716 int64_t cnt, delta; 717 bool should_complete; 718 719 if (s->ret < 0) { 720 ret = s->ret; 721 goto immediate_exit; 722 } 723 724 block_job_pause_point(&s->common); 725 726 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 727 /* s->common.offset contains the number of bytes already processed so 728 * far, cnt is the number of dirty sectors remaining and 729 * s->sectors_in_flight is the number of sectors currently being 730 * processed; together those are the current total operation length */ 731 s->common.len = s->common.offset + 732 (cnt + s->sectors_in_flight) * BDRV_SECTOR_SIZE; 733 734 /* Note that even when no rate limit is applied we need to yield 735 * periodically with no pending I/O so that bdrv_drain_all() returns. 736 * We do so every SLICE_TIME nanoseconds, or when there is an error, 737 * or when the source is clean, whichever comes first. 738 */ 739 delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns; 740 if (delta < SLICE_TIME && 741 s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { 742 if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || 743 (cnt == 0 && s->in_flight > 0)) { 744 trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt); 745 mirror_wait_for_io(s); 746 continue; 747 } else if (cnt != 0) { 748 delay_ns = mirror_iteration(s); 749 } 750 } 751 752 should_complete = false; 753 if (s->in_flight == 0 && cnt == 0) { 754 trace_mirror_before_flush(s); 755 if (!s->synced) { 756 if (mirror_flush(s) < 0) { 757 /* Go check s->ret. */ 758 continue; 759 } 760 /* We're out of the streaming phase. From now on, if the job 761 * is cancelled we will actually complete all pending I/O and 762 * report completion. This way, block-job-cancel will leave 763 * the target in a consistent state. 764 */ 765 block_job_event_ready(&s->common); 766 s->synced = true; 767 } 768 769 should_complete = s->should_complete || 770 block_job_is_cancelled(&s->common); 771 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 772 } 773 774 if (cnt == 0 && should_complete) { 775 /* The dirty bitmap is not updated while operations are pending. 776 * If we're about to exit, wait for pending operations before 777 * calling bdrv_get_dirty_count(bs), or we may exit while the 778 * source has dirty data to copy! 779 * 780 * Note that I/O can be submitted by the guest while 781 * mirror_populate runs, so pause it now. Before deciding 782 * whether to switch to target check one last time if I/O has 783 * come in the meanwhile, and if not flush the data to disk. 784 */ 785 trace_mirror_before_drain(s, cnt); 786 787 bdrv_drained_begin(bs); 788 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 789 if (cnt > 0 || mirror_flush(s) < 0) { 790 bdrv_drained_end(bs); 791 continue; 792 } 793 794 /* The two disks are in sync. Exit and report successful 795 * completion. 796 */ 797 assert(QLIST_EMPTY(&bs->tracked_requests)); 798 s->common.cancelled = false; 799 need_drain = false; 800 break; 801 } 802 803 ret = 0; 804 trace_mirror_before_sleep(s, cnt, s->synced, delay_ns); 805 if (!s->synced) { 806 block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); 807 if (block_job_is_cancelled(&s->common)) { 808 break; 809 } 810 } else if (!should_complete) { 811 delay_ns = (s->in_flight == 0 && cnt == 0 ? SLICE_TIME : 0); 812 block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); 813 } 814 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 815 } 816 817 immediate_exit: 818 if (s->in_flight > 0) { 819 /* We get here only if something went wrong. Either the job failed, 820 * or it was cancelled prematurely so that we do not guarantee that 821 * the target is a copy of the source. 822 */ 823 assert(ret < 0 || (!s->synced && block_job_is_cancelled(&s->common))); 824 assert(need_drain); 825 mirror_wait_for_all_io(s); 826 } 827 828 assert(s->in_flight == 0); 829 qemu_vfree(s->buf); 830 g_free(s->cow_bitmap); 831 g_free(s->in_flight_bitmap); 832 bdrv_dirty_iter_free(s->dbi); 833 bdrv_release_dirty_bitmap(bs, s->dirty_bitmap); 834 835 data = g_malloc(sizeof(*data)); 836 data->ret = ret; 837 838 if (need_drain) { 839 bdrv_drained_begin(bs); 840 } 841 block_job_defer_to_main_loop(&s->common, mirror_exit, data); 842 } 843 844 static void mirror_set_speed(BlockJob *job, int64_t speed, Error **errp) 845 { 846 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 847 848 if (speed < 0) { 849 error_setg(errp, QERR_INVALID_PARAMETER, "speed"); 850 return; 851 } 852 ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME); 853 } 854 855 static void mirror_complete(BlockJob *job, Error **errp) 856 { 857 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 858 BlockDriverState *src, *target; 859 860 src = blk_bs(job->blk); 861 target = blk_bs(s->target); 862 863 if (!s->synced) { 864 error_setg(errp, "The active block job '%s' cannot be completed", 865 job->id); 866 return; 867 } 868 869 if (s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { 870 int ret; 871 872 assert(!target->backing); 873 ret = bdrv_open_backing_file(target, NULL, "backing", errp); 874 if (ret < 0) { 875 return; 876 } 877 } 878 879 /* block all operations on to_replace bs */ 880 if (s->replaces) { 881 AioContext *replace_aio_context; 882 883 s->to_replace = bdrv_find_node(s->replaces); 884 if (!s->to_replace) { 885 error_setg(errp, "Node name '%s' not found", s->replaces); 886 return; 887 } 888 889 replace_aio_context = bdrv_get_aio_context(s->to_replace); 890 aio_context_acquire(replace_aio_context); 891 892 error_setg(&s->replace_blocker, 893 "block device is in use by block-job-complete"); 894 bdrv_op_block_all(s->to_replace, s->replace_blocker); 895 bdrv_ref(s->to_replace); 896 897 aio_context_release(replace_aio_context); 898 } 899 900 if (s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { 901 BlockDriverState *backing = s->is_none_mode ? src : s->base; 902 if (backing_bs(target) != backing) { 903 bdrv_set_backing_hd(target, backing); 904 } 905 } 906 907 s->should_complete = true; 908 block_job_enter(&s->common); 909 } 910 911 static void mirror_pause(BlockJob *job) 912 { 913 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 914 915 mirror_wait_for_all_io(s); 916 } 917 918 static void mirror_attached_aio_context(BlockJob *job, AioContext *new_context) 919 { 920 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 921 922 blk_set_aio_context(s->target, new_context); 923 } 924 925 static void mirror_drain(BlockJob *job) 926 { 927 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 928 929 /* Need to keep a reference in case blk_drain triggers execution 930 * of mirror_complete... 931 */ 932 if (s->target) { 933 BlockBackend *target = s->target; 934 blk_ref(target); 935 blk_drain(target); 936 blk_unref(target); 937 } 938 } 939 940 static const BlockJobDriver mirror_job_driver = { 941 .instance_size = sizeof(MirrorBlockJob), 942 .job_type = BLOCK_JOB_TYPE_MIRROR, 943 .set_speed = mirror_set_speed, 944 .start = mirror_run, 945 .complete = mirror_complete, 946 .pause = mirror_pause, 947 .attached_aio_context = mirror_attached_aio_context, 948 .drain = mirror_drain, 949 }; 950 951 static const BlockJobDriver commit_active_job_driver = { 952 .instance_size = sizeof(MirrorBlockJob), 953 .job_type = BLOCK_JOB_TYPE_COMMIT, 954 .set_speed = mirror_set_speed, 955 .start = mirror_run, 956 .complete = mirror_complete, 957 .pause = mirror_pause, 958 .attached_aio_context = mirror_attached_aio_context, 959 .drain = mirror_drain, 960 }; 961 962 static void mirror_start_job(const char *job_id, BlockDriverState *bs, 963 int creation_flags, BlockDriverState *target, 964 const char *replaces, int64_t speed, 965 uint32_t granularity, int64_t buf_size, 966 BlockMirrorBackingMode backing_mode, 967 BlockdevOnError on_source_error, 968 BlockdevOnError on_target_error, 969 bool unmap, 970 BlockCompletionFunc *cb, 971 void *opaque, Error **errp, 972 const BlockJobDriver *driver, 973 bool is_none_mode, BlockDriverState *base, 974 bool auto_complete) 975 { 976 MirrorBlockJob *s; 977 978 if (granularity == 0) { 979 granularity = bdrv_get_default_bitmap_granularity(target); 980 } 981 982 assert ((granularity & (granularity - 1)) == 0); 983 984 if (buf_size < 0) { 985 error_setg(errp, "Invalid parameter 'buf-size'"); 986 return; 987 } 988 989 if (buf_size == 0) { 990 buf_size = DEFAULT_MIRROR_BUF_SIZE; 991 } 992 993 s = block_job_create(job_id, driver, bs, speed, creation_flags, 994 cb, opaque, errp); 995 if (!s) { 996 return; 997 } 998 999 s->target = blk_new(); 1000 blk_insert_bs(s->target, target); 1001 1002 s->replaces = g_strdup(replaces); 1003 s->on_source_error = on_source_error; 1004 s->on_target_error = on_target_error; 1005 s->is_none_mode = is_none_mode; 1006 s->backing_mode = backing_mode; 1007 s->base = base; 1008 s->granularity = granularity; 1009 s->buf_size = ROUND_UP(buf_size, granularity); 1010 s->unmap = unmap; 1011 if (auto_complete) { 1012 s->should_complete = true; 1013 } 1014 1015 s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp); 1016 if (!s->dirty_bitmap) { 1017 g_free(s->replaces); 1018 blk_unref(s->target); 1019 block_job_unref(&s->common); 1020 return; 1021 } 1022 1023 block_job_add_bdrv(&s->common, target); 1024 /* In commit_active_start() all intermediate nodes disappear, so 1025 * any jobs in them must be blocked */ 1026 if (bdrv_chain_contains(bs, target)) { 1027 BlockDriverState *iter; 1028 for (iter = backing_bs(bs); iter != target; iter = backing_bs(iter)) { 1029 block_job_add_bdrv(&s->common, iter); 1030 } 1031 } 1032 1033 trace_mirror_start(bs, s, opaque); 1034 block_job_start(&s->common); 1035 } 1036 1037 void mirror_start(const char *job_id, BlockDriverState *bs, 1038 BlockDriverState *target, const char *replaces, 1039 int64_t speed, uint32_t granularity, int64_t buf_size, 1040 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, 1041 BlockdevOnError on_source_error, 1042 BlockdevOnError on_target_error, 1043 bool unmap, Error **errp) 1044 { 1045 bool is_none_mode; 1046 BlockDriverState *base; 1047 1048 if (mode == MIRROR_SYNC_MODE_INCREMENTAL) { 1049 error_setg(errp, "Sync mode 'incremental' not supported"); 1050 return; 1051 } 1052 is_none_mode = mode == MIRROR_SYNC_MODE_NONE; 1053 base = mode == MIRROR_SYNC_MODE_TOP ? backing_bs(bs) : NULL; 1054 mirror_start_job(job_id, bs, BLOCK_JOB_DEFAULT, target, replaces, 1055 speed, granularity, buf_size, backing_mode, 1056 on_source_error, on_target_error, unmap, NULL, NULL, errp, 1057 &mirror_job_driver, is_none_mode, base, false); 1058 } 1059 1060 void commit_active_start(const char *job_id, BlockDriverState *bs, 1061 BlockDriverState *base, int creation_flags, 1062 int64_t speed, BlockdevOnError on_error, 1063 BlockCompletionFunc *cb, void *opaque, Error **errp, 1064 bool auto_complete) 1065 { 1066 int64_t length, base_length; 1067 int orig_base_flags; 1068 int ret; 1069 Error *local_err = NULL; 1070 1071 orig_base_flags = bdrv_get_flags(base); 1072 1073 if (bdrv_reopen(base, bs->open_flags, errp)) { 1074 return; 1075 } 1076 1077 length = bdrv_getlength(bs); 1078 if (length < 0) { 1079 error_setg_errno(errp, -length, 1080 "Unable to determine length of %s", bs->filename); 1081 goto error_restore_flags; 1082 } 1083 1084 base_length = bdrv_getlength(base); 1085 if (base_length < 0) { 1086 error_setg_errno(errp, -base_length, 1087 "Unable to determine length of %s", base->filename); 1088 goto error_restore_flags; 1089 } 1090 1091 if (length > base_length) { 1092 ret = bdrv_truncate(base, length); 1093 if (ret < 0) { 1094 error_setg_errno(errp, -ret, 1095 "Top image %s is larger than base image %s, and " 1096 "resize of base image failed", 1097 bs->filename, base->filename); 1098 goto error_restore_flags; 1099 } 1100 } 1101 1102 mirror_start_job(job_id, bs, creation_flags, base, NULL, speed, 0, 0, 1103 MIRROR_LEAVE_BACKING_CHAIN, 1104 on_error, on_error, true, cb, opaque, &local_err, 1105 &commit_active_job_driver, false, base, auto_complete); 1106 if (local_err) { 1107 error_propagate(errp, local_err); 1108 goto error_restore_flags; 1109 } 1110 1111 return; 1112 1113 error_restore_flags: 1114 /* ignore error and errp for bdrv_reopen, because we want to propagate 1115 * the original error */ 1116 bdrv_reopen(base, orig_base_flags, NULL); 1117 return; 1118 } 1119