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 DEFAULT_MIRROR_BUF_SIZE (10 << 20) 27 28 /* The mirroring buffer is a list of granularity-sized chunks. 29 * Free chunks are organized in a list. 30 */ 31 typedef struct MirrorBuffer { 32 QSIMPLEQ_ENTRY(MirrorBuffer) next; 33 } MirrorBuffer; 34 35 typedef struct MirrorBlockJob { 36 BlockJob common; 37 RateLimit limit; 38 BlockBackend *target; 39 BlockDriverState *base; 40 /* The name of the graph node to replace */ 41 char *replaces; 42 /* The BDS to replace */ 43 BlockDriverState *to_replace; 44 /* Used to block operations on the drive-mirror-replace target */ 45 Error *replace_blocker; 46 bool is_none_mode; 47 BlockMirrorBackingMode backing_mode; 48 BlockdevOnError on_source_error, on_target_error; 49 bool synced; 50 bool should_complete; 51 int64_t granularity; 52 size_t buf_size; 53 int64_t bdev_length; 54 unsigned long *cow_bitmap; 55 BdrvDirtyBitmap *dirty_bitmap; 56 HBitmapIter hbi; 57 uint8_t *buf; 58 QSIMPLEQ_HEAD(, MirrorBuffer) buf_free; 59 int buf_free_count; 60 61 unsigned long *in_flight_bitmap; 62 int in_flight; 63 int sectors_in_flight; 64 int ret; 65 bool unmap; 66 bool waiting_for_io; 67 int target_cluster_sectors; 68 int max_iov; 69 } MirrorBlockJob; 70 71 typedef struct MirrorOp { 72 MirrorBlockJob *s; 73 QEMUIOVector qiov; 74 int64_t sector_num; 75 int nb_sectors; 76 } MirrorOp; 77 78 static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, 79 int error) 80 { 81 s->synced = false; 82 if (read) { 83 return block_job_error_action(&s->common, s->on_source_error, 84 true, error); 85 } else { 86 return block_job_error_action(&s->common, s->on_target_error, 87 false, error); 88 } 89 } 90 91 static void mirror_iteration_done(MirrorOp *op, int ret) 92 { 93 MirrorBlockJob *s = op->s; 94 struct iovec *iov; 95 int64_t chunk_num; 96 int i, nb_chunks, sectors_per_chunk; 97 98 trace_mirror_iteration_done(s, op->sector_num, op->nb_sectors, ret); 99 100 s->in_flight--; 101 s->sectors_in_flight -= op->nb_sectors; 102 iov = op->qiov.iov; 103 for (i = 0; i < op->qiov.niov; i++) { 104 MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base; 105 QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next); 106 s->buf_free_count++; 107 } 108 109 sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; 110 chunk_num = op->sector_num / sectors_per_chunk; 111 nb_chunks = DIV_ROUND_UP(op->nb_sectors, sectors_per_chunk); 112 bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks); 113 if (ret >= 0) { 114 if (s->cow_bitmap) { 115 bitmap_set(s->cow_bitmap, chunk_num, nb_chunks); 116 } 117 s->common.offset += (uint64_t)op->nb_sectors * BDRV_SECTOR_SIZE; 118 } 119 120 qemu_iovec_destroy(&op->qiov); 121 g_free(op); 122 123 if (s->waiting_for_io) { 124 qemu_coroutine_enter(s->common.co); 125 } 126 } 127 128 static void mirror_write_complete(void *opaque, int ret) 129 { 130 MirrorOp *op = opaque; 131 MirrorBlockJob *s = op->s; 132 if (ret < 0) { 133 BlockErrorAction action; 134 135 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->sector_num, op->nb_sectors); 136 action = mirror_error_action(s, false, -ret); 137 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 138 s->ret = ret; 139 } 140 } 141 mirror_iteration_done(op, ret); 142 } 143 144 static void mirror_read_complete(void *opaque, int ret) 145 { 146 MirrorOp *op = opaque; 147 MirrorBlockJob *s = op->s; 148 if (ret < 0) { 149 BlockErrorAction action; 150 151 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->sector_num, op->nb_sectors); 152 action = mirror_error_action(s, true, -ret); 153 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 154 s->ret = ret; 155 } 156 157 mirror_iteration_done(op, ret); 158 return; 159 } 160 blk_aio_pwritev(s->target, op->sector_num * BDRV_SECTOR_SIZE, &op->qiov, 161 0, mirror_write_complete, op); 162 } 163 164 static inline void mirror_clip_sectors(MirrorBlockJob *s, 165 int64_t sector_num, 166 int *nb_sectors) 167 { 168 *nb_sectors = MIN(*nb_sectors, 169 s->bdev_length / BDRV_SECTOR_SIZE - sector_num); 170 } 171 172 /* Round sector_num and/or nb_sectors to target cluster if COW is needed, and 173 * return the offset of the adjusted tail sector against original. */ 174 static int mirror_cow_align(MirrorBlockJob *s, 175 int64_t *sector_num, 176 int *nb_sectors) 177 { 178 bool need_cow; 179 int ret = 0; 180 int chunk_sectors = s->granularity >> BDRV_SECTOR_BITS; 181 int64_t align_sector_num = *sector_num; 182 int align_nb_sectors = *nb_sectors; 183 int max_sectors = chunk_sectors * s->max_iov; 184 185 need_cow = !test_bit(*sector_num / chunk_sectors, s->cow_bitmap); 186 need_cow |= !test_bit((*sector_num + *nb_sectors - 1) / chunk_sectors, 187 s->cow_bitmap); 188 if (need_cow) { 189 bdrv_round_sectors_to_clusters(blk_bs(s->target), *sector_num, 190 *nb_sectors, &align_sector_num, 191 &align_nb_sectors); 192 } 193 194 if (align_nb_sectors > max_sectors) { 195 align_nb_sectors = max_sectors; 196 if (need_cow) { 197 align_nb_sectors = QEMU_ALIGN_DOWN(align_nb_sectors, 198 s->target_cluster_sectors); 199 } 200 } 201 /* Clipping may result in align_nb_sectors unaligned to chunk boundary, but 202 * that doesn't matter because it's already the end of source image. */ 203 mirror_clip_sectors(s, align_sector_num, &align_nb_sectors); 204 205 ret = align_sector_num + align_nb_sectors - (*sector_num + *nb_sectors); 206 *sector_num = align_sector_num; 207 *nb_sectors = align_nb_sectors; 208 assert(ret >= 0); 209 return ret; 210 } 211 212 static inline void mirror_wait_for_io(MirrorBlockJob *s) 213 { 214 assert(!s->waiting_for_io); 215 s->waiting_for_io = true; 216 qemu_coroutine_yield(); 217 s->waiting_for_io = false; 218 } 219 220 /* Submit async read while handling COW. 221 * Returns: The number of sectors copied after and including sector_num, 222 * excluding any sectors copied prior to sector_num due to alignment. 223 * This will be nb_sectors if no alignment is necessary, or 224 * (new_end - sector_num) if tail is rounded up or down due to 225 * alignment or buffer limit. 226 */ 227 static int mirror_do_read(MirrorBlockJob *s, int64_t sector_num, 228 int nb_sectors) 229 { 230 BlockBackend *source = s->common.blk; 231 int sectors_per_chunk, nb_chunks; 232 int ret; 233 MirrorOp *op; 234 int max_sectors; 235 236 sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; 237 max_sectors = sectors_per_chunk * s->max_iov; 238 239 /* We can only handle as much as buf_size at a time. */ 240 nb_sectors = MIN(s->buf_size >> BDRV_SECTOR_BITS, nb_sectors); 241 nb_sectors = MIN(max_sectors, nb_sectors); 242 assert(nb_sectors); 243 ret = nb_sectors; 244 245 if (s->cow_bitmap) { 246 ret += mirror_cow_align(s, §or_num, &nb_sectors); 247 } 248 assert(nb_sectors << BDRV_SECTOR_BITS <= s->buf_size); 249 /* The sector range must meet granularity because: 250 * 1) Caller passes in aligned values; 251 * 2) mirror_cow_align is used only when target cluster is larger. */ 252 assert(!(sector_num % sectors_per_chunk)); 253 nb_chunks = DIV_ROUND_UP(nb_sectors, sectors_per_chunk); 254 255 while (s->buf_free_count < nb_chunks) { 256 trace_mirror_yield_in_flight(s, sector_num, s->in_flight); 257 mirror_wait_for_io(s); 258 } 259 260 /* Allocate a MirrorOp that is used as an AIO callback. */ 261 op = g_new(MirrorOp, 1); 262 op->s = s; 263 op->sector_num = sector_num; 264 op->nb_sectors = nb_sectors; 265 266 /* Now make a QEMUIOVector taking enough granularity-sized chunks 267 * from s->buf_free. 268 */ 269 qemu_iovec_init(&op->qiov, nb_chunks); 270 while (nb_chunks-- > 0) { 271 MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free); 272 size_t remaining = nb_sectors * BDRV_SECTOR_SIZE - op->qiov.size; 273 274 QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next); 275 s->buf_free_count--; 276 qemu_iovec_add(&op->qiov, buf, MIN(s->granularity, remaining)); 277 } 278 279 /* Copy the dirty cluster. */ 280 s->in_flight++; 281 s->sectors_in_flight += nb_sectors; 282 trace_mirror_one_iteration(s, sector_num, nb_sectors); 283 284 blk_aio_preadv(source, sector_num * BDRV_SECTOR_SIZE, &op->qiov, 0, 285 mirror_read_complete, op); 286 return ret; 287 } 288 289 static void mirror_do_zero_or_discard(MirrorBlockJob *s, 290 int64_t sector_num, 291 int nb_sectors, 292 bool is_discard) 293 { 294 MirrorOp *op; 295 296 /* Allocate a MirrorOp that is used as an AIO callback. The qiov is zeroed 297 * so the freeing in mirror_iteration_done is nop. */ 298 op = g_new0(MirrorOp, 1); 299 op->s = s; 300 op->sector_num = sector_num; 301 op->nb_sectors = nb_sectors; 302 303 s->in_flight++; 304 s->sectors_in_flight += nb_sectors; 305 if (is_discard) { 306 blk_aio_discard(s->target, sector_num, op->nb_sectors, 307 mirror_write_complete, op); 308 } else { 309 blk_aio_pwrite_zeroes(s->target, sector_num * BDRV_SECTOR_SIZE, 310 op->nb_sectors * BDRV_SECTOR_SIZE, 311 s->unmap ? BDRV_REQ_MAY_UNMAP : 0, 312 mirror_write_complete, op); 313 } 314 } 315 316 static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) 317 { 318 BlockDriverState *source = blk_bs(s->common.blk); 319 int64_t sector_num, first_chunk; 320 uint64_t delay_ns = 0; 321 /* At least the first dirty chunk is mirrored in one iteration. */ 322 int nb_chunks = 1; 323 int64_t end = s->bdev_length / BDRV_SECTOR_SIZE; 324 int sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; 325 326 sector_num = hbitmap_iter_next(&s->hbi); 327 if (sector_num < 0) { 328 bdrv_dirty_iter_init(s->dirty_bitmap, &s->hbi); 329 sector_num = hbitmap_iter_next(&s->hbi); 330 trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap)); 331 assert(sector_num >= 0); 332 } 333 334 first_chunk = sector_num / sectors_per_chunk; 335 while (test_bit(first_chunk, s->in_flight_bitmap)) { 336 trace_mirror_yield_in_flight(s, sector_num, s->in_flight); 337 mirror_wait_for_io(s); 338 } 339 340 block_job_pause_point(&s->common); 341 342 /* Find the number of consective dirty chunks following the first dirty 343 * one, and wait for in flight requests in them. */ 344 while (nb_chunks * sectors_per_chunk < (s->buf_size >> BDRV_SECTOR_BITS)) { 345 int64_t hbitmap_next; 346 int64_t next_sector = sector_num + nb_chunks * sectors_per_chunk; 347 int64_t next_chunk = next_sector / sectors_per_chunk; 348 if (next_sector >= end || 349 !bdrv_get_dirty(source, s->dirty_bitmap, next_sector)) { 350 break; 351 } 352 if (test_bit(next_chunk, s->in_flight_bitmap)) { 353 break; 354 } 355 356 hbitmap_next = hbitmap_iter_next(&s->hbi); 357 if (hbitmap_next > next_sector || hbitmap_next < 0) { 358 /* The bitmap iterator's cache is stale, refresh it */ 359 bdrv_set_dirty_iter(&s->hbi, next_sector); 360 hbitmap_next = hbitmap_iter_next(&s->hbi); 361 } 362 assert(hbitmap_next == next_sector); 363 nb_chunks++; 364 } 365 366 /* Clear dirty bits before querying the block status, because 367 * calling bdrv_get_block_status_above could yield - if some blocks are 368 * marked dirty in this window, we need to know. 369 */ 370 bdrv_reset_dirty_bitmap(s->dirty_bitmap, sector_num, 371 nb_chunks * sectors_per_chunk); 372 bitmap_set(s->in_flight_bitmap, sector_num / sectors_per_chunk, nb_chunks); 373 while (nb_chunks > 0 && sector_num < end) { 374 int ret; 375 int io_sectors; 376 BlockDriverState *file; 377 enum MirrorMethod { 378 MIRROR_METHOD_COPY, 379 MIRROR_METHOD_ZERO, 380 MIRROR_METHOD_DISCARD 381 } mirror_method = MIRROR_METHOD_COPY; 382 383 assert(!(sector_num % sectors_per_chunk)); 384 ret = bdrv_get_block_status_above(source, NULL, sector_num, 385 nb_chunks * sectors_per_chunk, 386 &io_sectors, &file); 387 if (ret < 0) { 388 io_sectors = nb_chunks * sectors_per_chunk; 389 } 390 391 io_sectors -= io_sectors % sectors_per_chunk; 392 if (io_sectors < sectors_per_chunk) { 393 io_sectors = sectors_per_chunk; 394 } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) { 395 int64_t target_sector_num; 396 int target_nb_sectors; 397 bdrv_round_sectors_to_clusters(blk_bs(s->target), sector_num, 398 io_sectors, &target_sector_num, 399 &target_nb_sectors); 400 if (target_sector_num == sector_num && 401 target_nb_sectors == io_sectors) { 402 mirror_method = ret & BDRV_BLOCK_ZERO ? 403 MIRROR_METHOD_ZERO : 404 MIRROR_METHOD_DISCARD; 405 } 406 } 407 408 mirror_clip_sectors(s, sector_num, &io_sectors); 409 switch (mirror_method) { 410 case MIRROR_METHOD_COPY: 411 io_sectors = mirror_do_read(s, sector_num, io_sectors); 412 break; 413 case MIRROR_METHOD_ZERO: 414 mirror_do_zero_or_discard(s, sector_num, io_sectors, false); 415 break; 416 case MIRROR_METHOD_DISCARD: 417 mirror_do_zero_or_discard(s, sector_num, io_sectors, true); 418 break; 419 default: 420 abort(); 421 } 422 assert(io_sectors); 423 sector_num += io_sectors; 424 nb_chunks -= DIV_ROUND_UP(io_sectors, sectors_per_chunk); 425 if (s->common.speed) { 426 delay_ns = ratelimit_calculate_delay(&s->limit, io_sectors); 427 } 428 } 429 return delay_ns; 430 } 431 432 static void mirror_free_init(MirrorBlockJob *s) 433 { 434 int granularity = s->granularity; 435 size_t buf_size = s->buf_size; 436 uint8_t *buf = s->buf; 437 438 assert(s->buf_free_count == 0); 439 QSIMPLEQ_INIT(&s->buf_free); 440 while (buf_size != 0) { 441 MirrorBuffer *cur = (MirrorBuffer *)buf; 442 QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); 443 s->buf_free_count++; 444 buf_size -= granularity; 445 buf += granularity; 446 } 447 } 448 449 static void mirror_drain(MirrorBlockJob *s) 450 { 451 while (s->in_flight > 0) { 452 mirror_wait_for_io(s); 453 } 454 } 455 456 typedef struct { 457 int ret; 458 } MirrorExitData; 459 460 static void mirror_exit(BlockJob *job, void *opaque) 461 { 462 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 463 MirrorExitData *data = opaque; 464 AioContext *replace_aio_context = NULL; 465 BlockDriverState *src = blk_bs(s->common.blk); 466 BlockDriverState *target_bs = blk_bs(s->target); 467 468 /* Make sure that the source BDS doesn't go away before we called 469 * block_job_completed(). */ 470 bdrv_ref(src); 471 472 if (s->to_replace) { 473 replace_aio_context = bdrv_get_aio_context(s->to_replace); 474 aio_context_acquire(replace_aio_context); 475 } 476 477 if (s->should_complete && data->ret == 0) { 478 BlockDriverState *to_replace = src; 479 if (s->to_replace) { 480 to_replace = s->to_replace; 481 } 482 483 if (bdrv_get_flags(target_bs) != bdrv_get_flags(to_replace)) { 484 bdrv_reopen(target_bs, bdrv_get_flags(to_replace), NULL); 485 } 486 487 /* The mirror job has no requests in flight any more, but we need to 488 * drain potential other users of the BDS before changing the graph. */ 489 bdrv_drained_begin(target_bs); 490 bdrv_replace_in_backing_chain(to_replace, target_bs); 491 bdrv_drained_end(target_bs); 492 493 /* We just changed the BDS the job BB refers to */ 494 blk_remove_bs(job->blk); 495 blk_insert_bs(job->blk, src); 496 } 497 if (s->to_replace) { 498 bdrv_op_unblock_all(s->to_replace, s->replace_blocker); 499 error_free(s->replace_blocker); 500 bdrv_unref(s->to_replace); 501 } 502 if (replace_aio_context) { 503 aio_context_release(replace_aio_context); 504 } 505 g_free(s->replaces); 506 bdrv_op_unblock_all(target_bs, s->common.blocker); 507 blk_unref(s->target); 508 block_job_completed(&s->common, data->ret); 509 g_free(data); 510 bdrv_drained_end(src); 511 if (qemu_get_aio_context() == bdrv_get_aio_context(src)) { 512 aio_enable_external(iohandler_get_aio_context()); 513 } 514 bdrv_unref(src); 515 } 516 517 static void coroutine_fn mirror_run(void *opaque) 518 { 519 MirrorBlockJob *s = opaque; 520 MirrorExitData *data; 521 BlockDriverState *bs = blk_bs(s->common.blk); 522 BlockDriverState *target_bs = blk_bs(s->target); 523 int64_t sector_num, end, length; 524 uint64_t last_pause_ns; 525 BlockDriverInfo bdi; 526 char backing_filename[2]; /* we only need 2 characters because we are only 527 checking for a NULL string */ 528 int ret = 0; 529 int n; 530 int target_cluster_size = BDRV_SECTOR_SIZE; 531 532 if (block_job_is_cancelled(&s->common)) { 533 goto immediate_exit; 534 } 535 536 s->bdev_length = bdrv_getlength(bs); 537 if (s->bdev_length < 0) { 538 ret = s->bdev_length; 539 goto immediate_exit; 540 } else if (s->bdev_length == 0) { 541 /* Report BLOCK_JOB_READY and wait for complete. */ 542 block_job_event_ready(&s->common); 543 s->synced = true; 544 while (!block_job_is_cancelled(&s->common) && !s->should_complete) { 545 block_job_yield(&s->common); 546 } 547 s->common.cancelled = false; 548 goto immediate_exit; 549 } 550 551 length = DIV_ROUND_UP(s->bdev_length, s->granularity); 552 s->in_flight_bitmap = bitmap_new(length); 553 554 /* If we have no backing file yet in the destination, we cannot let 555 * the destination do COW. Instead, we copy sectors around the 556 * dirty data if needed. We need a bitmap to do that. 557 */ 558 bdrv_get_backing_filename(target_bs, backing_filename, 559 sizeof(backing_filename)); 560 if (!bdrv_get_info(target_bs, &bdi) && bdi.cluster_size) { 561 target_cluster_size = bdi.cluster_size; 562 } 563 if (backing_filename[0] && !target_bs->backing 564 && s->granularity < target_cluster_size) { 565 s->buf_size = MAX(s->buf_size, target_cluster_size); 566 s->cow_bitmap = bitmap_new(length); 567 } 568 s->target_cluster_sectors = target_cluster_size >> BDRV_SECTOR_BITS; 569 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); 570 571 end = s->bdev_length / BDRV_SECTOR_SIZE; 572 s->buf = qemu_try_blockalign(bs, s->buf_size); 573 if (s->buf == NULL) { 574 ret = -ENOMEM; 575 goto immediate_exit; 576 } 577 578 mirror_free_init(s); 579 580 last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 581 if (!s->is_none_mode) { 582 /* First part, loop on the sectors and initialize the dirty bitmap. */ 583 BlockDriverState *base = s->base; 584 bool mark_all_dirty = s->base == NULL && !bdrv_has_zero_init(target_bs); 585 586 for (sector_num = 0; sector_num < end; ) { 587 /* Just to make sure we are not exceeding int limit. */ 588 int nb_sectors = MIN(INT_MAX >> BDRV_SECTOR_BITS, 589 end - sector_num); 590 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 591 592 if (now - last_pause_ns > SLICE_TIME) { 593 last_pause_ns = now; 594 block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, 0); 595 } else { 596 block_job_pause_point(&s->common); 597 } 598 599 if (block_job_is_cancelled(&s->common)) { 600 goto immediate_exit; 601 } 602 603 ret = bdrv_is_allocated_above(bs, base, sector_num, nb_sectors, &n); 604 605 if (ret < 0) { 606 goto immediate_exit; 607 } 608 609 assert(n > 0); 610 if (ret == 1 || mark_all_dirty) { 611 bdrv_set_dirty_bitmap(s->dirty_bitmap, sector_num, n); 612 } 613 sector_num += n; 614 } 615 } 616 617 bdrv_dirty_iter_init(s->dirty_bitmap, &s->hbi); 618 for (;;) { 619 uint64_t delay_ns = 0; 620 int64_t cnt; 621 bool should_complete; 622 623 if (s->ret < 0) { 624 ret = s->ret; 625 goto immediate_exit; 626 } 627 628 block_job_pause_point(&s->common); 629 630 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 631 /* s->common.offset contains the number of bytes already processed so 632 * far, cnt is the number of dirty sectors remaining and 633 * s->sectors_in_flight is the number of sectors currently being 634 * processed; together those are the current total operation length */ 635 s->common.len = s->common.offset + 636 (cnt + s->sectors_in_flight) * BDRV_SECTOR_SIZE; 637 638 /* Note that even when no rate limit is applied we need to yield 639 * periodically with no pending I/O so that bdrv_drain_all() returns. 640 * We do so every SLICE_TIME nanoseconds, or when there is an error, 641 * or when the source is clean, whichever comes first. 642 */ 643 if (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - last_pause_ns < SLICE_TIME && 644 s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { 645 if (s->in_flight == MAX_IN_FLIGHT || s->buf_free_count == 0 || 646 (cnt == 0 && s->in_flight > 0)) { 647 trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt); 648 mirror_wait_for_io(s); 649 continue; 650 } else if (cnt != 0) { 651 delay_ns = mirror_iteration(s); 652 } 653 } 654 655 should_complete = false; 656 if (s->in_flight == 0 && cnt == 0) { 657 trace_mirror_before_flush(s); 658 ret = blk_flush(s->target); 659 if (ret < 0) { 660 if (mirror_error_action(s, false, -ret) == 661 BLOCK_ERROR_ACTION_REPORT) { 662 goto immediate_exit; 663 } 664 } else { 665 /* We're out of the streaming phase. From now on, if the job 666 * is cancelled we will actually complete all pending I/O and 667 * report completion. This way, block-job-cancel will leave 668 * the target in a consistent state. 669 */ 670 if (!s->synced) { 671 block_job_event_ready(&s->common); 672 s->synced = true; 673 } 674 675 should_complete = s->should_complete || 676 block_job_is_cancelled(&s->common); 677 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 678 } 679 } 680 681 if (cnt == 0 && should_complete) { 682 /* The dirty bitmap is not updated while operations are pending. 683 * If we're about to exit, wait for pending operations before 684 * calling bdrv_get_dirty_count(bs), or we may exit while the 685 * source has dirty data to copy! 686 * 687 * Note that I/O can be submitted by the guest while 688 * mirror_populate runs. 689 */ 690 trace_mirror_before_drain(s, cnt); 691 bdrv_co_drain(bs); 692 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 693 } 694 695 ret = 0; 696 trace_mirror_before_sleep(s, cnt, s->synced, delay_ns); 697 if (!s->synced) { 698 block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); 699 if (block_job_is_cancelled(&s->common)) { 700 break; 701 } 702 } else if (!should_complete) { 703 delay_ns = (s->in_flight == 0 && cnt == 0 ? SLICE_TIME : 0); 704 block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); 705 } else if (cnt == 0) { 706 /* The two disks are in sync. Exit and report successful 707 * completion. 708 */ 709 assert(QLIST_EMPTY(&bs->tracked_requests)); 710 s->common.cancelled = false; 711 break; 712 } 713 last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 714 } 715 716 immediate_exit: 717 if (s->in_flight > 0) { 718 /* We get here only if something went wrong. Either the job failed, 719 * or it was cancelled prematurely so that we do not guarantee that 720 * the target is a copy of the source. 721 */ 722 assert(ret < 0 || (!s->synced && block_job_is_cancelled(&s->common))); 723 mirror_drain(s); 724 } 725 726 assert(s->in_flight == 0); 727 qemu_vfree(s->buf); 728 g_free(s->cow_bitmap); 729 g_free(s->in_flight_bitmap); 730 bdrv_release_dirty_bitmap(bs, s->dirty_bitmap); 731 732 data = g_malloc(sizeof(*data)); 733 data->ret = ret; 734 /* Before we switch to target in mirror_exit, make sure data doesn't 735 * change. */ 736 bdrv_drained_begin(bs); 737 if (qemu_get_aio_context() == bdrv_get_aio_context(bs)) { 738 /* FIXME: virtio host notifiers run on iohandler_ctx, therefore the 739 * above bdrv_drained_end isn't enough to quiesce it. This is ugly, we 740 * need a block layer API change to achieve this. */ 741 aio_disable_external(iohandler_get_aio_context()); 742 } 743 block_job_defer_to_main_loop(&s->common, mirror_exit, data); 744 } 745 746 static void mirror_set_speed(BlockJob *job, int64_t speed, Error **errp) 747 { 748 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 749 750 if (speed < 0) { 751 error_setg(errp, QERR_INVALID_PARAMETER, "speed"); 752 return; 753 } 754 ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME); 755 } 756 757 static void mirror_complete(BlockJob *job, Error **errp) 758 { 759 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 760 BlockDriverState *src, *target; 761 762 src = blk_bs(job->blk); 763 target = blk_bs(s->target); 764 765 if (!s->synced) { 766 error_setg(errp, "The active block job '%s' cannot be completed", 767 job->id); 768 return; 769 } 770 771 if (s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { 772 int ret; 773 774 assert(!target->backing); 775 ret = bdrv_open_backing_file(target, NULL, "backing", errp); 776 if (ret < 0) { 777 return; 778 } 779 } 780 781 /* block all operations on to_replace bs */ 782 if (s->replaces) { 783 AioContext *replace_aio_context; 784 785 s->to_replace = bdrv_find_node(s->replaces); 786 if (!s->to_replace) { 787 error_setg(errp, "Node name '%s' not found", s->replaces); 788 return; 789 } 790 791 replace_aio_context = bdrv_get_aio_context(s->to_replace); 792 aio_context_acquire(replace_aio_context); 793 794 error_setg(&s->replace_blocker, 795 "block device is in use by block-job-complete"); 796 bdrv_op_block_all(s->to_replace, s->replace_blocker); 797 bdrv_ref(s->to_replace); 798 799 aio_context_release(replace_aio_context); 800 } 801 802 if (s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { 803 BlockDriverState *backing = s->is_none_mode ? src : s->base; 804 if (backing_bs(target) != backing) { 805 bdrv_set_backing_hd(target, backing); 806 } 807 } 808 809 s->should_complete = true; 810 block_job_enter(&s->common); 811 } 812 813 /* There is no matching mirror_resume() because mirror_run() will begin 814 * iterating again when the job is resumed. 815 */ 816 static void coroutine_fn mirror_pause(BlockJob *job) 817 { 818 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 819 820 mirror_drain(s); 821 } 822 823 static void mirror_attached_aio_context(BlockJob *job, AioContext *new_context) 824 { 825 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 826 827 blk_set_aio_context(s->target, new_context); 828 } 829 830 static const BlockJobDriver mirror_job_driver = { 831 .instance_size = sizeof(MirrorBlockJob), 832 .job_type = BLOCK_JOB_TYPE_MIRROR, 833 .set_speed = mirror_set_speed, 834 .complete = mirror_complete, 835 .pause = mirror_pause, 836 .attached_aio_context = mirror_attached_aio_context, 837 }; 838 839 static const BlockJobDriver commit_active_job_driver = { 840 .instance_size = sizeof(MirrorBlockJob), 841 .job_type = BLOCK_JOB_TYPE_COMMIT, 842 .set_speed = mirror_set_speed, 843 .complete = mirror_complete, 844 .pause = mirror_pause, 845 .attached_aio_context = mirror_attached_aio_context, 846 }; 847 848 static void mirror_start_job(const char *job_id, BlockDriverState *bs, 849 BlockDriverState *target, const char *replaces, 850 int64_t speed, uint32_t granularity, 851 int64_t buf_size, 852 BlockMirrorBackingMode backing_mode, 853 BlockdevOnError on_source_error, 854 BlockdevOnError on_target_error, 855 bool unmap, 856 BlockCompletionFunc *cb, 857 void *opaque, Error **errp, 858 const BlockJobDriver *driver, 859 bool is_none_mode, BlockDriverState *base) 860 { 861 MirrorBlockJob *s; 862 863 if (granularity == 0) { 864 granularity = bdrv_get_default_bitmap_granularity(target); 865 } 866 867 assert ((granularity & (granularity - 1)) == 0); 868 869 if (buf_size < 0) { 870 error_setg(errp, "Invalid parameter 'buf-size'"); 871 return; 872 } 873 874 if (buf_size == 0) { 875 buf_size = DEFAULT_MIRROR_BUF_SIZE; 876 } 877 878 s = block_job_create(job_id, driver, bs, speed, cb, opaque, errp); 879 if (!s) { 880 return; 881 } 882 883 s->target = blk_new(); 884 blk_insert_bs(s->target, target); 885 886 s->replaces = g_strdup(replaces); 887 s->on_source_error = on_source_error; 888 s->on_target_error = on_target_error; 889 s->is_none_mode = is_none_mode; 890 s->backing_mode = backing_mode; 891 s->base = base; 892 s->granularity = granularity; 893 s->buf_size = ROUND_UP(buf_size, granularity); 894 s->unmap = unmap; 895 896 s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp); 897 if (!s->dirty_bitmap) { 898 g_free(s->replaces); 899 blk_unref(s->target); 900 block_job_unref(&s->common); 901 return; 902 } 903 904 bdrv_op_block_all(target, s->common.blocker); 905 906 s->common.co = qemu_coroutine_create(mirror_run, s); 907 trace_mirror_start(bs, s, s->common.co, opaque); 908 qemu_coroutine_enter(s->common.co); 909 } 910 911 void mirror_start(const char *job_id, BlockDriverState *bs, 912 BlockDriverState *target, const char *replaces, 913 int64_t speed, uint32_t granularity, int64_t buf_size, 914 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, 915 BlockdevOnError on_source_error, 916 BlockdevOnError on_target_error, 917 bool unmap, 918 BlockCompletionFunc *cb, 919 void *opaque, Error **errp) 920 { 921 bool is_none_mode; 922 BlockDriverState *base; 923 924 if (mode == MIRROR_SYNC_MODE_INCREMENTAL) { 925 error_setg(errp, "Sync mode 'incremental' not supported"); 926 return; 927 } 928 is_none_mode = mode == MIRROR_SYNC_MODE_NONE; 929 base = mode == MIRROR_SYNC_MODE_TOP ? backing_bs(bs) : NULL; 930 mirror_start_job(job_id, bs, target, replaces, 931 speed, granularity, buf_size, backing_mode, 932 on_source_error, on_target_error, unmap, cb, opaque, errp, 933 &mirror_job_driver, is_none_mode, base); 934 } 935 936 void commit_active_start(const char *job_id, BlockDriverState *bs, 937 BlockDriverState *base, int64_t speed, 938 BlockdevOnError on_error, 939 BlockCompletionFunc *cb, 940 void *opaque, Error **errp) 941 { 942 int64_t length, base_length; 943 int orig_base_flags; 944 int ret; 945 Error *local_err = NULL; 946 947 orig_base_flags = bdrv_get_flags(base); 948 949 if (bdrv_reopen(base, bs->open_flags, errp)) { 950 return; 951 } 952 953 length = bdrv_getlength(bs); 954 if (length < 0) { 955 error_setg_errno(errp, -length, 956 "Unable to determine length of %s", bs->filename); 957 goto error_restore_flags; 958 } 959 960 base_length = bdrv_getlength(base); 961 if (base_length < 0) { 962 error_setg_errno(errp, -base_length, 963 "Unable to determine length of %s", base->filename); 964 goto error_restore_flags; 965 } 966 967 if (length > base_length) { 968 ret = bdrv_truncate(base, length); 969 if (ret < 0) { 970 error_setg_errno(errp, -ret, 971 "Top image %s is larger than base image %s, and " 972 "resize of base image failed", 973 bs->filename, base->filename); 974 goto error_restore_flags; 975 } 976 } 977 978 mirror_start_job(job_id, bs, base, NULL, speed, 0, 0, 979 MIRROR_LEAVE_BACKING_CHAIN, 980 on_error, on_error, false, cb, opaque, &local_err, 981 &commit_active_job_driver, false, base); 982 if (local_err) { 983 error_propagate(errp, local_err); 984 goto error_restore_flags; 985 } 986 987 return; 988 989 error_restore_flags: 990 /* ignore error and errp for bdrv_reopen, because we want to propagate 991 * the original error */ 992 bdrv_reopen(base, orig_base_flags, NULL); 993 return; 994 } 995