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