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 "qemu/cutils.h" 16 #include "qemu/coroutine.h" 17 #include "qemu/range.h" 18 #include "trace.h" 19 #include "block/blockjob_int.h" 20 #include "block/block_int.h" 21 #include "sysemu/block-backend.h" 22 #include "qapi/error.h" 23 #include "qapi/qmp/qerror.h" 24 #include "qemu/ratelimit.h" 25 #include "qemu/bitmap.h" 26 #include "qemu/memalign.h" 27 28 #define MAX_IN_FLIGHT 16 29 #define MAX_IO_BYTES (1 << 20) /* 1 Mb */ 30 #define DEFAULT_MIRROR_BUF_SIZE (MAX_IN_FLIGHT * MAX_IO_BYTES) 31 32 /* The mirroring buffer is a list of granularity-sized chunks. 33 * Free chunks are organized in a list. 34 */ 35 typedef struct MirrorBuffer { 36 QSIMPLEQ_ENTRY(MirrorBuffer) next; 37 } MirrorBuffer; 38 39 typedef struct MirrorOp MirrorOp; 40 41 typedef struct MirrorBlockJob { 42 BlockJob common; 43 BlockBackend *target; 44 BlockDriverState *mirror_top_bs; 45 BlockDriverState *base; 46 BlockDriverState *base_overlay; 47 48 /* The name of the graph node to replace */ 49 char *replaces; 50 /* The BDS to replace */ 51 BlockDriverState *to_replace; 52 /* Used to block operations on the drive-mirror-replace target */ 53 Error *replace_blocker; 54 bool is_none_mode; 55 BlockMirrorBackingMode backing_mode; 56 /* Whether the target image requires explicit zero-initialization */ 57 bool zero_target; 58 MirrorCopyMode copy_mode; 59 BlockdevOnError on_source_error, on_target_error; 60 /* Set when the target is synced (dirty bitmap is clean, nothing 61 * in flight) and the job is running in active mode */ 62 bool actively_synced; 63 bool should_complete; 64 int64_t granularity; 65 size_t buf_size; 66 int64_t bdev_length; 67 unsigned long *cow_bitmap; 68 BdrvDirtyBitmap *dirty_bitmap; 69 BdrvDirtyBitmapIter *dbi; 70 uint8_t *buf; 71 QSIMPLEQ_HEAD(, MirrorBuffer) buf_free; 72 int buf_free_count; 73 74 uint64_t last_pause_ns; 75 unsigned long *in_flight_bitmap; 76 unsigned in_flight; 77 int64_t bytes_in_flight; 78 QTAILQ_HEAD(, MirrorOp) ops_in_flight; 79 int ret; 80 bool unmap; 81 int target_cluster_size; 82 int max_iov; 83 bool initial_zeroing_ongoing; 84 int in_active_write_counter; 85 bool prepared; 86 bool in_drain; 87 } MirrorBlockJob; 88 89 typedef struct MirrorBDSOpaque { 90 MirrorBlockJob *job; 91 bool stop; 92 bool is_commit; 93 } MirrorBDSOpaque; 94 95 struct MirrorOp { 96 MirrorBlockJob *s; 97 QEMUIOVector qiov; 98 int64_t offset; 99 uint64_t bytes; 100 101 /* The pointee is set by mirror_co_read(), mirror_co_zero(), and 102 * mirror_co_discard() before yielding for the first time */ 103 int64_t *bytes_handled; 104 105 bool is_pseudo_op; 106 bool is_active_write; 107 bool is_in_flight; 108 CoQueue waiting_requests; 109 Coroutine *co; 110 MirrorOp *waiting_for_op; 111 112 QTAILQ_ENTRY(MirrorOp) next; 113 }; 114 115 typedef enum MirrorMethod { 116 MIRROR_METHOD_COPY, 117 MIRROR_METHOD_ZERO, 118 MIRROR_METHOD_DISCARD, 119 } MirrorMethod; 120 121 static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, 122 int error) 123 { 124 s->actively_synced = false; 125 if (read) { 126 return block_job_error_action(&s->common, s->on_source_error, 127 true, error); 128 } else { 129 return block_job_error_action(&s->common, s->on_target_error, 130 false, error); 131 } 132 } 133 134 static void coroutine_fn mirror_wait_on_conflicts(MirrorOp *self, 135 MirrorBlockJob *s, 136 uint64_t offset, 137 uint64_t bytes) 138 { 139 uint64_t self_start_chunk = offset / s->granularity; 140 uint64_t self_end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 141 uint64_t self_nb_chunks = self_end_chunk - self_start_chunk; 142 143 while (find_next_bit(s->in_flight_bitmap, self_end_chunk, 144 self_start_chunk) < self_end_chunk && 145 s->ret >= 0) 146 { 147 MirrorOp *op; 148 149 QTAILQ_FOREACH(op, &s->ops_in_flight, next) { 150 uint64_t op_start_chunk = op->offset / s->granularity; 151 uint64_t op_nb_chunks = DIV_ROUND_UP(op->offset + op->bytes, 152 s->granularity) - 153 op_start_chunk; 154 155 if (op == self) { 156 continue; 157 } 158 159 if (ranges_overlap(self_start_chunk, self_nb_chunks, 160 op_start_chunk, op_nb_chunks)) 161 { 162 if (self) { 163 /* 164 * If the operation is already (indirectly) waiting for us, 165 * or will wait for us as soon as it wakes up, then just go 166 * on (instead of producing a deadlock in the former case). 167 */ 168 if (op->waiting_for_op) { 169 continue; 170 } 171 172 self->waiting_for_op = op; 173 } 174 175 qemu_co_queue_wait(&op->waiting_requests, NULL); 176 177 if (self) { 178 self->waiting_for_op = NULL; 179 } 180 181 break; 182 } 183 } 184 } 185 } 186 187 static void coroutine_fn mirror_iteration_done(MirrorOp *op, int ret) 188 { 189 MirrorBlockJob *s = op->s; 190 struct iovec *iov; 191 int64_t chunk_num; 192 int i, nb_chunks; 193 194 trace_mirror_iteration_done(s, op->offset, op->bytes, ret); 195 196 s->in_flight--; 197 s->bytes_in_flight -= op->bytes; 198 iov = op->qiov.iov; 199 for (i = 0; i < op->qiov.niov; i++) { 200 MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base; 201 QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next); 202 s->buf_free_count++; 203 } 204 205 chunk_num = op->offset / s->granularity; 206 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity); 207 208 bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks); 209 QTAILQ_REMOVE(&s->ops_in_flight, op, next); 210 if (ret >= 0) { 211 if (s->cow_bitmap) { 212 bitmap_set(s->cow_bitmap, chunk_num, nb_chunks); 213 } 214 if (!s->initial_zeroing_ongoing) { 215 job_progress_update(&s->common.job, op->bytes); 216 } 217 } 218 qemu_iovec_destroy(&op->qiov); 219 220 qemu_co_queue_restart_all(&op->waiting_requests); 221 g_free(op); 222 } 223 224 static void coroutine_fn mirror_write_complete(MirrorOp *op, int ret) 225 { 226 MirrorBlockJob *s = op->s; 227 228 if (ret < 0) { 229 BlockErrorAction action; 230 231 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes); 232 action = mirror_error_action(s, false, -ret); 233 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 234 s->ret = ret; 235 } 236 } 237 238 mirror_iteration_done(op, ret); 239 } 240 241 static void coroutine_fn mirror_read_complete(MirrorOp *op, int ret) 242 { 243 MirrorBlockJob *s = op->s; 244 245 if (ret < 0) { 246 BlockErrorAction action; 247 248 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes); 249 action = mirror_error_action(s, true, -ret); 250 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 251 s->ret = ret; 252 } 253 254 mirror_iteration_done(op, ret); 255 return; 256 } 257 258 ret = blk_co_pwritev(s->target, op->offset, op->qiov.size, &op->qiov, 0); 259 mirror_write_complete(op, ret); 260 } 261 262 /* Clip bytes relative to offset to not exceed end-of-file */ 263 static inline int64_t mirror_clip_bytes(MirrorBlockJob *s, 264 int64_t offset, 265 int64_t bytes) 266 { 267 return MIN(bytes, s->bdev_length - offset); 268 } 269 270 /* Round offset and/or bytes to target cluster if COW is needed, and 271 * return the offset of the adjusted tail against original. */ 272 static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset, 273 uint64_t *bytes) 274 { 275 bool need_cow; 276 int ret = 0; 277 int64_t align_offset = *offset; 278 int64_t align_bytes = *bytes; 279 int max_bytes = s->granularity * s->max_iov; 280 281 need_cow = !test_bit(*offset / s->granularity, s->cow_bitmap); 282 need_cow |= !test_bit((*offset + *bytes - 1) / s->granularity, 283 s->cow_bitmap); 284 if (need_cow) { 285 bdrv_round_to_clusters(blk_bs(s->target), *offset, *bytes, 286 &align_offset, &align_bytes); 287 } 288 289 if (align_bytes > max_bytes) { 290 align_bytes = max_bytes; 291 if (need_cow) { 292 align_bytes = QEMU_ALIGN_DOWN(align_bytes, s->target_cluster_size); 293 } 294 } 295 /* Clipping may result in align_bytes unaligned to chunk boundary, but 296 * that doesn't matter because it's already the end of source image. */ 297 align_bytes = mirror_clip_bytes(s, align_offset, align_bytes); 298 299 ret = align_offset + align_bytes - (*offset + *bytes); 300 *offset = align_offset; 301 *bytes = align_bytes; 302 assert(ret >= 0); 303 return ret; 304 } 305 306 static inline void coroutine_fn 307 mirror_wait_for_any_operation(MirrorBlockJob *s, bool active) 308 { 309 MirrorOp *op; 310 311 QTAILQ_FOREACH(op, &s->ops_in_flight, next) { 312 /* Do not wait on pseudo ops, because it may in turn wait on 313 * some other operation to start, which may in fact be the 314 * caller of this function. Since there is only one pseudo op 315 * at any given time, we will always find some real operation 316 * to wait on. */ 317 if (!op->is_pseudo_op && op->is_in_flight && 318 op->is_active_write == active) 319 { 320 qemu_co_queue_wait(&op->waiting_requests, NULL); 321 return; 322 } 323 } 324 abort(); 325 } 326 327 static inline void coroutine_fn 328 mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s) 329 { 330 /* Only non-active operations use up in-flight slots */ 331 mirror_wait_for_any_operation(s, false); 332 } 333 334 /* Perform a mirror copy operation. 335 * 336 * *op->bytes_handled is set to the number of bytes copied after and 337 * including offset, excluding any bytes copied prior to offset due 338 * to alignment. This will be op->bytes if no alignment is necessary, 339 * or (new_end - op->offset) if the tail is rounded up or down due to 340 * alignment or buffer limit. 341 */ 342 static void coroutine_fn mirror_co_read(void *opaque) 343 { 344 MirrorOp *op = opaque; 345 MirrorBlockJob *s = op->s; 346 int nb_chunks; 347 uint64_t ret; 348 uint64_t max_bytes; 349 350 max_bytes = s->granularity * s->max_iov; 351 352 /* We can only handle as much as buf_size at a time. */ 353 op->bytes = MIN(s->buf_size, MIN(max_bytes, op->bytes)); 354 assert(op->bytes); 355 assert(op->bytes < BDRV_REQUEST_MAX_BYTES); 356 *op->bytes_handled = op->bytes; 357 358 if (s->cow_bitmap) { 359 *op->bytes_handled += mirror_cow_align(s, &op->offset, &op->bytes); 360 } 361 /* Cannot exceed BDRV_REQUEST_MAX_BYTES + INT_MAX */ 362 assert(*op->bytes_handled <= UINT_MAX); 363 assert(op->bytes <= s->buf_size); 364 /* The offset is granularity-aligned because: 365 * 1) Caller passes in aligned values; 366 * 2) mirror_cow_align is used only when target cluster is larger. */ 367 assert(QEMU_IS_ALIGNED(op->offset, s->granularity)); 368 /* The range is sector-aligned, since bdrv_getlength() rounds up. */ 369 assert(QEMU_IS_ALIGNED(op->bytes, BDRV_SECTOR_SIZE)); 370 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity); 371 372 while (s->buf_free_count < nb_chunks) { 373 trace_mirror_yield_in_flight(s, op->offset, s->in_flight); 374 mirror_wait_for_free_in_flight_slot(s); 375 } 376 377 /* Now make a QEMUIOVector taking enough granularity-sized chunks 378 * from s->buf_free. 379 */ 380 qemu_iovec_init(&op->qiov, nb_chunks); 381 while (nb_chunks-- > 0) { 382 MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free); 383 size_t remaining = op->bytes - op->qiov.size; 384 385 QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next); 386 s->buf_free_count--; 387 qemu_iovec_add(&op->qiov, buf, MIN(s->granularity, remaining)); 388 } 389 390 /* Copy the dirty cluster. */ 391 s->in_flight++; 392 s->bytes_in_flight += op->bytes; 393 op->is_in_flight = true; 394 trace_mirror_one_iteration(s, op->offset, op->bytes); 395 396 ret = bdrv_co_preadv(s->mirror_top_bs->backing, op->offset, op->bytes, 397 &op->qiov, 0); 398 mirror_read_complete(op, ret); 399 } 400 401 static void coroutine_fn mirror_co_zero(void *opaque) 402 { 403 MirrorOp *op = opaque; 404 int ret; 405 406 op->s->in_flight++; 407 op->s->bytes_in_flight += op->bytes; 408 *op->bytes_handled = op->bytes; 409 op->is_in_flight = true; 410 411 ret = blk_co_pwrite_zeroes(op->s->target, op->offset, op->bytes, 412 op->s->unmap ? BDRV_REQ_MAY_UNMAP : 0); 413 mirror_write_complete(op, ret); 414 } 415 416 static void coroutine_fn mirror_co_discard(void *opaque) 417 { 418 MirrorOp *op = opaque; 419 int ret; 420 421 op->s->in_flight++; 422 op->s->bytes_in_flight += op->bytes; 423 *op->bytes_handled = op->bytes; 424 op->is_in_flight = true; 425 426 ret = blk_co_pdiscard(op->s->target, op->offset, op->bytes); 427 mirror_write_complete(op, ret); 428 } 429 430 static unsigned mirror_perform(MirrorBlockJob *s, int64_t offset, 431 unsigned bytes, MirrorMethod mirror_method) 432 { 433 MirrorOp *op; 434 Coroutine *co; 435 int64_t bytes_handled = -1; 436 437 op = g_new(MirrorOp, 1); 438 *op = (MirrorOp){ 439 .s = s, 440 .offset = offset, 441 .bytes = bytes, 442 .bytes_handled = &bytes_handled, 443 }; 444 qemu_co_queue_init(&op->waiting_requests); 445 446 switch (mirror_method) { 447 case MIRROR_METHOD_COPY: 448 co = qemu_coroutine_create(mirror_co_read, op); 449 break; 450 case MIRROR_METHOD_ZERO: 451 co = qemu_coroutine_create(mirror_co_zero, op); 452 break; 453 case MIRROR_METHOD_DISCARD: 454 co = qemu_coroutine_create(mirror_co_discard, op); 455 break; 456 default: 457 abort(); 458 } 459 op->co = co; 460 461 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 462 qemu_coroutine_enter(co); 463 /* At this point, ownership of op has been moved to the coroutine 464 * and the object may already be freed */ 465 466 /* Assert that this value has been set */ 467 assert(bytes_handled >= 0); 468 469 /* Same assertion as in mirror_co_read() (and for mirror_co_read() 470 * and mirror_co_discard(), bytes_handled == op->bytes, which 471 * is the @bytes parameter given to this function) */ 472 assert(bytes_handled <= UINT_MAX); 473 return bytes_handled; 474 } 475 476 static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) 477 { 478 BlockDriverState *source = s->mirror_top_bs->backing->bs; 479 MirrorOp *pseudo_op; 480 int64_t offset; 481 uint64_t delay_ns = 0, ret = 0; 482 /* At least the first dirty chunk is mirrored in one iteration. */ 483 int nb_chunks = 1; 484 bool write_zeroes_ok = bdrv_can_write_zeroes_with_unmap(blk_bs(s->target)); 485 int max_io_bytes = MAX(s->buf_size / MAX_IN_FLIGHT, MAX_IO_BYTES); 486 487 bdrv_dirty_bitmap_lock(s->dirty_bitmap); 488 offset = bdrv_dirty_iter_next(s->dbi); 489 if (offset < 0) { 490 bdrv_set_dirty_iter(s->dbi, 0); 491 offset = bdrv_dirty_iter_next(s->dbi); 492 trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap)); 493 assert(offset >= 0); 494 } 495 bdrv_dirty_bitmap_unlock(s->dirty_bitmap); 496 497 mirror_wait_on_conflicts(NULL, s, offset, 1); 498 499 job_pause_point(&s->common.job); 500 501 /* Find the number of consective dirty chunks following the first dirty 502 * one, and wait for in flight requests in them. */ 503 bdrv_dirty_bitmap_lock(s->dirty_bitmap); 504 while (nb_chunks * s->granularity < s->buf_size) { 505 int64_t next_dirty; 506 int64_t next_offset = offset + nb_chunks * s->granularity; 507 int64_t next_chunk = next_offset / s->granularity; 508 if (next_offset >= s->bdev_length || 509 !bdrv_dirty_bitmap_get_locked(s->dirty_bitmap, next_offset)) { 510 break; 511 } 512 if (test_bit(next_chunk, s->in_flight_bitmap)) { 513 break; 514 } 515 516 next_dirty = bdrv_dirty_iter_next(s->dbi); 517 if (next_dirty > next_offset || next_dirty < 0) { 518 /* The bitmap iterator's cache is stale, refresh it */ 519 bdrv_set_dirty_iter(s->dbi, next_offset); 520 next_dirty = bdrv_dirty_iter_next(s->dbi); 521 } 522 assert(next_dirty == next_offset); 523 nb_chunks++; 524 } 525 526 /* Clear dirty bits before querying the block status, because 527 * calling bdrv_block_status_above could yield - if some blocks are 528 * marked dirty in this window, we need to know. 529 */ 530 bdrv_reset_dirty_bitmap_locked(s->dirty_bitmap, offset, 531 nb_chunks * s->granularity); 532 bdrv_dirty_bitmap_unlock(s->dirty_bitmap); 533 534 /* Before claiming an area in the in-flight bitmap, we have to 535 * create a MirrorOp for it so that conflicting requests can wait 536 * for it. mirror_perform() will create the real MirrorOps later, 537 * for now we just create a pseudo operation that will wake up all 538 * conflicting requests once all real operations have been 539 * launched. */ 540 pseudo_op = g_new(MirrorOp, 1); 541 *pseudo_op = (MirrorOp){ 542 .offset = offset, 543 .bytes = nb_chunks * s->granularity, 544 .is_pseudo_op = true, 545 }; 546 qemu_co_queue_init(&pseudo_op->waiting_requests); 547 QTAILQ_INSERT_TAIL(&s->ops_in_flight, pseudo_op, next); 548 549 bitmap_set(s->in_flight_bitmap, offset / s->granularity, nb_chunks); 550 while (nb_chunks > 0 && offset < s->bdev_length) { 551 int ret; 552 int64_t io_bytes; 553 int64_t io_bytes_acct; 554 MirrorMethod mirror_method = MIRROR_METHOD_COPY; 555 556 assert(!(offset % s->granularity)); 557 ret = bdrv_block_status_above(source, NULL, offset, 558 nb_chunks * s->granularity, 559 &io_bytes, NULL, NULL); 560 if (ret < 0) { 561 io_bytes = MIN(nb_chunks * s->granularity, max_io_bytes); 562 } else if (ret & BDRV_BLOCK_DATA) { 563 io_bytes = MIN(io_bytes, max_io_bytes); 564 } 565 566 io_bytes -= io_bytes % s->granularity; 567 if (io_bytes < s->granularity) { 568 io_bytes = s->granularity; 569 } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) { 570 int64_t target_offset; 571 int64_t target_bytes; 572 bdrv_round_to_clusters(blk_bs(s->target), offset, io_bytes, 573 &target_offset, &target_bytes); 574 if (target_offset == offset && 575 target_bytes == io_bytes) { 576 mirror_method = ret & BDRV_BLOCK_ZERO ? 577 MIRROR_METHOD_ZERO : 578 MIRROR_METHOD_DISCARD; 579 } 580 } 581 582 while (s->in_flight >= MAX_IN_FLIGHT) { 583 trace_mirror_yield_in_flight(s, offset, s->in_flight); 584 mirror_wait_for_free_in_flight_slot(s); 585 } 586 587 if (s->ret < 0) { 588 ret = 0; 589 goto fail; 590 } 591 592 io_bytes = mirror_clip_bytes(s, offset, io_bytes); 593 io_bytes = mirror_perform(s, offset, io_bytes, mirror_method); 594 if (mirror_method != MIRROR_METHOD_COPY && write_zeroes_ok) { 595 io_bytes_acct = 0; 596 } else { 597 io_bytes_acct = io_bytes; 598 } 599 assert(io_bytes); 600 offset += io_bytes; 601 nb_chunks -= DIV_ROUND_UP(io_bytes, s->granularity); 602 delay_ns = block_job_ratelimit_get_delay(&s->common, io_bytes_acct); 603 } 604 605 ret = delay_ns; 606 fail: 607 QTAILQ_REMOVE(&s->ops_in_flight, pseudo_op, next); 608 qemu_co_queue_restart_all(&pseudo_op->waiting_requests); 609 g_free(pseudo_op); 610 611 return ret; 612 } 613 614 static void mirror_free_init(MirrorBlockJob *s) 615 { 616 int granularity = s->granularity; 617 size_t buf_size = s->buf_size; 618 uint8_t *buf = s->buf; 619 620 assert(s->buf_free_count == 0); 621 QSIMPLEQ_INIT(&s->buf_free); 622 while (buf_size != 0) { 623 MirrorBuffer *cur = (MirrorBuffer *)buf; 624 QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); 625 s->buf_free_count++; 626 buf_size -= granularity; 627 buf += granularity; 628 } 629 } 630 631 /* This is also used for the .pause callback. There is no matching 632 * mirror_resume() because mirror_run() will begin iterating again 633 * when the job is resumed. 634 */ 635 static void coroutine_fn mirror_wait_for_all_io(MirrorBlockJob *s) 636 { 637 while (s->in_flight > 0) { 638 mirror_wait_for_free_in_flight_slot(s); 639 } 640 } 641 642 /** 643 * mirror_exit_common: handle both abort() and prepare() cases. 644 * for .prepare, returns 0 on success and -errno on failure. 645 * for .abort cases, denoted by abort = true, MUST return 0. 646 */ 647 static int mirror_exit_common(Job *job) 648 { 649 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 650 BlockJob *bjob = &s->common; 651 MirrorBDSOpaque *bs_opaque; 652 AioContext *replace_aio_context = NULL; 653 BlockDriverState *src; 654 BlockDriverState *target_bs; 655 BlockDriverState *mirror_top_bs; 656 Error *local_err = NULL; 657 bool abort = job->ret < 0; 658 int ret = 0; 659 660 if (s->prepared) { 661 return 0; 662 } 663 s->prepared = true; 664 665 mirror_top_bs = s->mirror_top_bs; 666 bs_opaque = mirror_top_bs->opaque; 667 src = mirror_top_bs->backing->bs; 668 target_bs = blk_bs(s->target); 669 670 if (bdrv_chain_contains(src, target_bs)) { 671 bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs); 672 } 673 674 bdrv_release_dirty_bitmap(s->dirty_bitmap); 675 676 /* Make sure that the source BDS doesn't go away during bdrv_replace_node, 677 * before we can call bdrv_drained_end */ 678 bdrv_ref(src); 679 bdrv_ref(mirror_top_bs); 680 bdrv_ref(target_bs); 681 682 /* 683 * Remove target parent that still uses BLK_PERM_WRITE/RESIZE before 684 * inserting target_bs at s->to_replace, where we might not be able to get 685 * these permissions. 686 */ 687 blk_unref(s->target); 688 s->target = NULL; 689 690 /* We don't access the source any more. Dropping any WRITE/RESIZE is 691 * required before it could become a backing file of target_bs. Not having 692 * these permissions any more means that we can't allow any new requests on 693 * mirror_top_bs from now on, so keep it drained. */ 694 bdrv_drained_begin(mirror_top_bs); 695 bs_opaque->stop = true; 696 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 697 &error_abort); 698 if (!abort && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { 699 BlockDriverState *backing = s->is_none_mode ? src : s->base; 700 BlockDriverState *unfiltered_target = bdrv_skip_filters(target_bs); 701 702 if (bdrv_cow_bs(unfiltered_target) != backing) { 703 bdrv_set_backing_hd(unfiltered_target, backing, &local_err); 704 if (local_err) { 705 error_report_err(local_err); 706 local_err = NULL; 707 ret = -EPERM; 708 } 709 } 710 } else if (!abort && s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { 711 assert(!bdrv_backing_chain_next(target_bs)); 712 ret = bdrv_open_backing_file(bdrv_skip_filters(target_bs), NULL, 713 "backing", &local_err); 714 if (ret < 0) { 715 error_report_err(local_err); 716 local_err = NULL; 717 } 718 } 719 720 if (s->to_replace) { 721 replace_aio_context = bdrv_get_aio_context(s->to_replace); 722 aio_context_acquire(replace_aio_context); 723 } 724 725 if (s->should_complete && !abort) { 726 BlockDriverState *to_replace = s->to_replace ?: src; 727 bool ro = bdrv_is_read_only(to_replace); 728 729 if (ro != bdrv_is_read_only(target_bs)) { 730 bdrv_reopen_set_read_only(target_bs, ro, NULL); 731 } 732 733 /* The mirror job has no requests in flight any more, but we need to 734 * drain potential other users of the BDS before changing the graph. */ 735 assert(s->in_drain); 736 bdrv_drained_begin(target_bs); 737 /* 738 * Cannot use check_to_replace_node() here, because that would 739 * check for an op blocker on @to_replace, and we have our own 740 * there. 741 */ 742 if (bdrv_recurse_can_replace(src, to_replace)) { 743 bdrv_replace_node(to_replace, target_bs, &local_err); 744 } else { 745 error_setg(&local_err, "Can no longer replace '%s' by '%s', " 746 "because it can no longer be guaranteed that doing so " 747 "would not lead to an abrupt change of visible data", 748 to_replace->node_name, target_bs->node_name); 749 } 750 bdrv_drained_end(target_bs); 751 if (local_err) { 752 error_report_err(local_err); 753 ret = -EPERM; 754 } 755 } 756 if (s->to_replace) { 757 bdrv_op_unblock_all(s->to_replace, s->replace_blocker); 758 error_free(s->replace_blocker); 759 bdrv_unref(s->to_replace); 760 } 761 if (replace_aio_context) { 762 aio_context_release(replace_aio_context); 763 } 764 g_free(s->replaces); 765 bdrv_unref(target_bs); 766 767 /* 768 * Remove the mirror filter driver from the graph. Before this, get rid of 769 * the blockers on the intermediate nodes so that the resulting state is 770 * valid. 771 */ 772 block_job_remove_all_bdrv(bjob); 773 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort); 774 775 bs_opaque->job = NULL; 776 777 bdrv_drained_end(src); 778 bdrv_drained_end(mirror_top_bs); 779 s->in_drain = false; 780 bdrv_unref(mirror_top_bs); 781 bdrv_unref(src); 782 783 return ret; 784 } 785 786 static int mirror_prepare(Job *job) 787 { 788 return mirror_exit_common(job); 789 } 790 791 static void mirror_abort(Job *job) 792 { 793 int ret = mirror_exit_common(job); 794 assert(ret == 0); 795 } 796 797 static void coroutine_fn mirror_throttle(MirrorBlockJob *s) 798 { 799 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 800 801 if (now - s->last_pause_ns > BLOCK_JOB_SLICE_TIME) { 802 s->last_pause_ns = now; 803 job_sleep_ns(&s->common.job, 0); 804 } else { 805 job_pause_point(&s->common.job); 806 } 807 } 808 809 static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) 810 { 811 int64_t offset; 812 BlockDriverState *bs = s->mirror_top_bs->backing->bs; 813 BlockDriverState *target_bs = blk_bs(s->target); 814 int ret; 815 int64_t count; 816 817 if (s->zero_target) { 818 if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { 819 bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length); 820 return 0; 821 } 822 823 s->initial_zeroing_ongoing = true; 824 for (offset = 0; offset < s->bdev_length; ) { 825 int bytes = MIN(s->bdev_length - offset, 826 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 827 828 mirror_throttle(s); 829 830 if (job_is_cancelled(&s->common.job)) { 831 s->initial_zeroing_ongoing = false; 832 return 0; 833 } 834 835 if (s->in_flight >= MAX_IN_FLIGHT) { 836 trace_mirror_yield(s, UINT64_MAX, s->buf_free_count, 837 s->in_flight); 838 mirror_wait_for_free_in_flight_slot(s); 839 continue; 840 } 841 842 mirror_perform(s, offset, bytes, MIRROR_METHOD_ZERO); 843 offset += bytes; 844 } 845 846 mirror_wait_for_all_io(s); 847 s->initial_zeroing_ongoing = false; 848 } 849 850 /* First part, loop on the sectors and initialize the dirty bitmap. */ 851 for (offset = 0; offset < s->bdev_length; ) { 852 /* Just to make sure we are not exceeding int limit. */ 853 int bytes = MIN(s->bdev_length - offset, 854 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 855 856 mirror_throttle(s); 857 858 if (job_is_cancelled(&s->common.job)) { 859 return 0; 860 } 861 862 ret = bdrv_is_allocated_above(bs, s->base_overlay, true, offset, bytes, 863 &count); 864 if (ret < 0) { 865 return ret; 866 } 867 868 assert(count); 869 if (ret > 0) { 870 bdrv_set_dirty_bitmap(s->dirty_bitmap, offset, count); 871 } 872 offset += count; 873 } 874 return 0; 875 } 876 877 /* Called when going out of the streaming phase to flush the bulk of the 878 * data to the medium, or just before completing. 879 */ 880 static int mirror_flush(MirrorBlockJob *s) 881 { 882 int ret = blk_flush(s->target); 883 if (ret < 0) { 884 if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) { 885 s->ret = ret; 886 } 887 } 888 return ret; 889 } 890 891 static int coroutine_fn mirror_run(Job *job, Error **errp) 892 { 893 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 894 BlockDriverState *bs = s->mirror_top_bs->backing->bs; 895 BlockDriverState *target_bs = blk_bs(s->target); 896 bool need_drain = true; 897 int64_t length; 898 int64_t target_length; 899 BlockDriverInfo bdi; 900 char backing_filename[2]; /* we only need 2 characters because we are only 901 checking for a NULL string */ 902 int ret = 0; 903 904 if (job_is_cancelled(&s->common.job)) { 905 goto immediate_exit; 906 } 907 908 s->bdev_length = bdrv_getlength(bs); 909 if (s->bdev_length < 0) { 910 ret = s->bdev_length; 911 goto immediate_exit; 912 } 913 914 target_length = blk_getlength(s->target); 915 if (target_length < 0) { 916 ret = target_length; 917 goto immediate_exit; 918 } 919 920 /* Active commit must resize the base image if its size differs from the 921 * active layer. */ 922 if (s->base == blk_bs(s->target)) { 923 if (s->bdev_length > target_length) { 924 ret = blk_truncate(s->target, s->bdev_length, false, 925 PREALLOC_MODE_OFF, 0, NULL); 926 if (ret < 0) { 927 goto immediate_exit; 928 } 929 } 930 } else if (s->bdev_length != target_length) { 931 error_setg(errp, "Source and target image have different sizes"); 932 ret = -EINVAL; 933 goto immediate_exit; 934 } 935 936 if (s->bdev_length == 0) { 937 /* Transition to the READY state and wait for complete. */ 938 job_transition_to_ready(&s->common.job); 939 s->actively_synced = true; 940 while (!job_cancel_requested(&s->common.job) && !s->should_complete) { 941 job_yield(&s->common.job); 942 } 943 goto immediate_exit; 944 } 945 946 length = DIV_ROUND_UP(s->bdev_length, s->granularity); 947 s->in_flight_bitmap = bitmap_new(length); 948 949 /* If we have no backing file yet in the destination, we cannot let 950 * the destination do COW. Instead, we copy sectors around the 951 * dirty data if needed. We need a bitmap to do that. 952 */ 953 bdrv_get_backing_filename(target_bs, backing_filename, 954 sizeof(backing_filename)); 955 if (!bdrv_get_info(target_bs, &bdi) && bdi.cluster_size) { 956 s->target_cluster_size = bdi.cluster_size; 957 } else { 958 s->target_cluster_size = BDRV_SECTOR_SIZE; 959 } 960 if (backing_filename[0] && !bdrv_backing_chain_next(target_bs) && 961 s->granularity < s->target_cluster_size) { 962 s->buf_size = MAX(s->buf_size, s->target_cluster_size); 963 s->cow_bitmap = bitmap_new(length); 964 } 965 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); 966 967 s->buf = qemu_try_blockalign(bs, s->buf_size); 968 if (s->buf == NULL) { 969 ret = -ENOMEM; 970 goto immediate_exit; 971 } 972 973 mirror_free_init(s); 974 975 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 976 if (!s->is_none_mode) { 977 ret = mirror_dirty_init(s); 978 if (ret < 0 || job_is_cancelled(&s->common.job)) { 979 goto immediate_exit; 980 } 981 } 982 983 assert(!s->dbi); 984 s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap); 985 for (;;) { 986 uint64_t delay_ns = 0; 987 int64_t cnt, delta; 988 bool should_complete; 989 990 /* Do not start passive operations while there are active 991 * writes in progress */ 992 while (s->in_active_write_counter) { 993 mirror_wait_for_any_operation(s, true); 994 } 995 996 if (s->ret < 0) { 997 ret = s->ret; 998 goto immediate_exit; 999 } 1000 1001 job_pause_point(&s->common.job); 1002 1003 if (job_is_cancelled(&s->common.job)) { 1004 ret = 0; 1005 goto immediate_exit; 1006 } 1007 1008 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1009 /* cnt is the number of dirty bytes remaining and s->bytes_in_flight is 1010 * the number of bytes currently being processed; together those are 1011 * the current remaining operation length */ 1012 job_progress_set_remaining(&s->common.job, s->bytes_in_flight + cnt); 1013 1014 /* Note that even when no rate limit is applied we need to yield 1015 * periodically with no pending I/O so that bdrv_drain_all() returns. 1016 * We do so every BLKOCK_JOB_SLICE_TIME nanoseconds, or when there is 1017 * an error, or when the source is clean, whichever comes first. */ 1018 delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns; 1019 if (delta < BLOCK_JOB_SLICE_TIME && 1020 s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { 1021 if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || 1022 (cnt == 0 && s->in_flight > 0)) { 1023 trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight); 1024 mirror_wait_for_free_in_flight_slot(s); 1025 continue; 1026 } else if (cnt != 0) { 1027 delay_ns = mirror_iteration(s); 1028 } 1029 } 1030 1031 should_complete = false; 1032 if (s->in_flight == 0 && cnt == 0) { 1033 trace_mirror_before_flush(s); 1034 if (!job_is_ready(&s->common.job)) { 1035 if (mirror_flush(s) < 0) { 1036 /* Go check s->ret. */ 1037 continue; 1038 } 1039 /* We're out of the streaming phase. From now on, if the job 1040 * is cancelled we will actually complete all pending I/O and 1041 * report completion. This way, block-job-cancel will leave 1042 * the target in a consistent state. 1043 */ 1044 job_transition_to_ready(&s->common.job); 1045 if (s->copy_mode != MIRROR_COPY_MODE_BACKGROUND) { 1046 s->actively_synced = true; 1047 } 1048 } 1049 1050 should_complete = s->should_complete || 1051 job_cancel_requested(&s->common.job); 1052 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1053 } 1054 1055 if (cnt == 0 && should_complete) { 1056 /* The dirty bitmap is not updated while operations are pending. 1057 * If we're about to exit, wait for pending operations before 1058 * calling bdrv_get_dirty_count(bs), or we may exit while the 1059 * source has dirty data to copy! 1060 * 1061 * Note that I/O can be submitted by the guest while 1062 * mirror_populate runs, so pause it now. Before deciding 1063 * whether to switch to target check one last time if I/O has 1064 * come in the meanwhile, and if not flush the data to disk. 1065 */ 1066 trace_mirror_before_drain(s, cnt); 1067 1068 s->in_drain = true; 1069 bdrv_drained_begin(bs); 1070 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1071 if (cnt > 0 || mirror_flush(s) < 0) { 1072 bdrv_drained_end(bs); 1073 s->in_drain = false; 1074 continue; 1075 } 1076 1077 /* The two disks are in sync. Exit and report successful 1078 * completion. 1079 */ 1080 assert(QLIST_EMPTY(&bs->tracked_requests)); 1081 need_drain = false; 1082 break; 1083 } 1084 1085 if (job_is_ready(&s->common.job) && !should_complete) { 1086 delay_ns = (s->in_flight == 0 && 1087 cnt == 0 ? BLOCK_JOB_SLICE_TIME : 0); 1088 } 1089 trace_mirror_before_sleep(s, cnt, job_is_ready(&s->common.job), 1090 delay_ns); 1091 job_sleep_ns(&s->common.job, delay_ns); 1092 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 1093 } 1094 1095 immediate_exit: 1096 if (s->in_flight > 0) { 1097 /* We get here only if something went wrong. Either the job failed, 1098 * or it was cancelled prematurely so that we do not guarantee that 1099 * the target is a copy of the source. 1100 */ 1101 assert(ret < 0 || job_is_cancelled(&s->common.job)); 1102 assert(need_drain); 1103 mirror_wait_for_all_io(s); 1104 } 1105 1106 assert(s->in_flight == 0); 1107 qemu_vfree(s->buf); 1108 g_free(s->cow_bitmap); 1109 g_free(s->in_flight_bitmap); 1110 bdrv_dirty_iter_free(s->dbi); 1111 1112 if (need_drain) { 1113 s->in_drain = true; 1114 bdrv_drained_begin(bs); 1115 } 1116 1117 return ret; 1118 } 1119 1120 static void mirror_complete(Job *job, Error **errp) 1121 { 1122 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1123 1124 if (!job_is_ready(job)) { 1125 error_setg(errp, "The active block job '%s' cannot be completed", 1126 job->id); 1127 return; 1128 } 1129 1130 /* block all operations on to_replace bs */ 1131 if (s->replaces) { 1132 AioContext *replace_aio_context; 1133 1134 s->to_replace = bdrv_find_node(s->replaces); 1135 if (!s->to_replace) { 1136 error_setg(errp, "Node name '%s' not found", s->replaces); 1137 return; 1138 } 1139 1140 replace_aio_context = bdrv_get_aio_context(s->to_replace); 1141 aio_context_acquire(replace_aio_context); 1142 1143 /* TODO Translate this into child freeze system. */ 1144 error_setg(&s->replace_blocker, 1145 "block device is in use by block-job-complete"); 1146 bdrv_op_block_all(s->to_replace, s->replace_blocker); 1147 bdrv_ref(s->to_replace); 1148 1149 aio_context_release(replace_aio_context); 1150 } 1151 1152 s->should_complete = true; 1153 1154 /* If the job is paused, it will be re-entered when it is resumed */ 1155 if (!job->paused) { 1156 job_enter(job); 1157 } 1158 } 1159 1160 static void coroutine_fn mirror_pause(Job *job) 1161 { 1162 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1163 1164 mirror_wait_for_all_io(s); 1165 } 1166 1167 static bool mirror_drained_poll(BlockJob *job) 1168 { 1169 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1170 1171 /* If the job isn't paused nor cancelled, we can't be sure that it won't 1172 * issue more requests. We make an exception if we've reached this point 1173 * from one of our own drain sections, to avoid a deadlock waiting for 1174 * ourselves. 1175 */ 1176 if (!s->common.job.paused && !job_is_cancelled(&job->job) && !s->in_drain) { 1177 return true; 1178 } 1179 1180 return !!s->in_flight; 1181 } 1182 1183 static bool mirror_cancel(Job *job, bool force) 1184 { 1185 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1186 BlockDriverState *target = blk_bs(s->target); 1187 1188 /* 1189 * Before the job is READY, we treat any cancellation like a 1190 * force-cancellation. 1191 */ 1192 force = force || !job_is_ready(job); 1193 1194 if (force) { 1195 bdrv_cancel_in_flight(target); 1196 } 1197 return force; 1198 } 1199 1200 static bool commit_active_cancel(Job *job, bool force) 1201 { 1202 /* Same as above in mirror_cancel() */ 1203 return force || !job_is_ready(job); 1204 } 1205 1206 static const BlockJobDriver mirror_job_driver = { 1207 .job_driver = { 1208 .instance_size = sizeof(MirrorBlockJob), 1209 .job_type = JOB_TYPE_MIRROR, 1210 .free = block_job_free, 1211 .user_resume = block_job_user_resume, 1212 .run = mirror_run, 1213 .prepare = mirror_prepare, 1214 .abort = mirror_abort, 1215 .pause = mirror_pause, 1216 .complete = mirror_complete, 1217 .cancel = mirror_cancel, 1218 }, 1219 .drained_poll = mirror_drained_poll, 1220 }; 1221 1222 static const BlockJobDriver commit_active_job_driver = { 1223 .job_driver = { 1224 .instance_size = sizeof(MirrorBlockJob), 1225 .job_type = JOB_TYPE_COMMIT, 1226 .free = block_job_free, 1227 .user_resume = block_job_user_resume, 1228 .run = mirror_run, 1229 .prepare = mirror_prepare, 1230 .abort = mirror_abort, 1231 .pause = mirror_pause, 1232 .complete = mirror_complete, 1233 .cancel = commit_active_cancel, 1234 }, 1235 .drained_poll = mirror_drained_poll, 1236 }; 1237 1238 static void coroutine_fn 1239 do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, 1240 uint64_t offset, uint64_t bytes, 1241 QEMUIOVector *qiov, int flags) 1242 { 1243 int ret; 1244 size_t qiov_offset = 0; 1245 int64_t bitmap_offset, bitmap_end; 1246 1247 if (!QEMU_IS_ALIGNED(offset, job->granularity) && 1248 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset)) 1249 { 1250 /* 1251 * Dirty unaligned padding: ignore it. 1252 * 1253 * Reasoning: 1254 * 1. If we copy it, we can't reset corresponding bit in 1255 * dirty_bitmap as there may be some "dirty" bytes still not 1256 * copied. 1257 * 2. It's already dirty, so skipping it we don't diverge mirror 1258 * progress. 1259 * 1260 * Note, that because of this, guest write may have no contribution 1261 * into mirror converge, but that's not bad, as we have background 1262 * process of mirroring. If under some bad circumstances (high guest 1263 * IO load) background process starve, we will not converge anyway, 1264 * even if each write will contribute, as guest is not guaranteed to 1265 * rewrite the whole disk. 1266 */ 1267 qiov_offset = QEMU_ALIGN_UP(offset, job->granularity) - offset; 1268 if (bytes <= qiov_offset) { 1269 /* nothing to do after shrink */ 1270 return; 1271 } 1272 offset += qiov_offset; 1273 bytes -= qiov_offset; 1274 } 1275 1276 if (!QEMU_IS_ALIGNED(offset + bytes, job->granularity) && 1277 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset + bytes - 1)) 1278 { 1279 uint64_t tail = (offset + bytes) % job->granularity; 1280 1281 if (bytes <= tail) { 1282 /* nothing to do after shrink */ 1283 return; 1284 } 1285 bytes -= tail; 1286 } 1287 1288 /* 1289 * Tails are either clean or shrunk, so for bitmap resetting 1290 * we safely align the range down. 1291 */ 1292 bitmap_offset = QEMU_ALIGN_UP(offset, job->granularity); 1293 bitmap_end = QEMU_ALIGN_DOWN(offset + bytes, job->granularity); 1294 if (bitmap_offset < bitmap_end) { 1295 bdrv_reset_dirty_bitmap(job->dirty_bitmap, bitmap_offset, 1296 bitmap_end - bitmap_offset); 1297 } 1298 1299 job_progress_increase_remaining(&job->common.job, bytes); 1300 1301 switch (method) { 1302 case MIRROR_METHOD_COPY: 1303 ret = blk_co_pwritev_part(job->target, offset, bytes, 1304 qiov, qiov_offset, flags); 1305 break; 1306 1307 case MIRROR_METHOD_ZERO: 1308 assert(!qiov); 1309 ret = blk_co_pwrite_zeroes(job->target, offset, bytes, flags); 1310 break; 1311 1312 case MIRROR_METHOD_DISCARD: 1313 assert(!qiov); 1314 ret = blk_co_pdiscard(job->target, offset, bytes); 1315 break; 1316 1317 default: 1318 abort(); 1319 } 1320 1321 if (ret >= 0) { 1322 job_progress_update(&job->common.job, bytes); 1323 } else { 1324 BlockErrorAction action; 1325 1326 /* 1327 * We failed, so we should mark dirty the whole area, aligned up. 1328 * Note that we don't care about shrunk tails if any: they were dirty 1329 * at function start, and they must be still dirty, as we've locked 1330 * the region for in-flight op. 1331 */ 1332 bitmap_offset = QEMU_ALIGN_DOWN(offset, job->granularity); 1333 bitmap_end = QEMU_ALIGN_UP(offset + bytes, job->granularity); 1334 bdrv_set_dirty_bitmap(job->dirty_bitmap, bitmap_offset, 1335 bitmap_end - bitmap_offset); 1336 job->actively_synced = false; 1337 1338 action = mirror_error_action(job, false, -ret); 1339 if (action == BLOCK_ERROR_ACTION_REPORT) { 1340 if (!job->ret) { 1341 job->ret = ret; 1342 } 1343 } 1344 } 1345 } 1346 1347 static MirrorOp *coroutine_fn active_write_prepare(MirrorBlockJob *s, 1348 uint64_t offset, 1349 uint64_t bytes) 1350 { 1351 MirrorOp *op; 1352 uint64_t start_chunk = offset / s->granularity; 1353 uint64_t end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 1354 1355 op = g_new(MirrorOp, 1); 1356 *op = (MirrorOp){ 1357 .s = s, 1358 .offset = offset, 1359 .bytes = bytes, 1360 .is_active_write = true, 1361 .is_in_flight = true, 1362 .co = qemu_coroutine_self(), 1363 }; 1364 qemu_co_queue_init(&op->waiting_requests); 1365 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 1366 1367 s->in_active_write_counter++; 1368 1369 mirror_wait_on_conflicts(op, s, offset, bytes); 1370 1371 bitmap_set(s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1372 1373 return op; 1374 } 1375 1376 static void coroutine_fn active_write_settle(MirrorOp *op) 1377 { 1378 uint64_t start_chunk = op->offset / op->s->granularity; 1379 uint64_t end_chunk = DIV_ROUND_UP(op->offset + op->bytes, 1380 op->s->granularity); 1381 1382 if (!--op->s->in_active_write_counter && op->s->actively_synced) { 1383 BdrvChild *source = op->s->mirror_top_bs->backing; 1384 1385 if (QLIST_FIRST(&source->bs->parents) == source && 1386 QLIST_NEXT(source, next_parent) == NULL) 1387 { 1388 /* Assert that we are back in sync once all active write 1389 * operations are settled. 1390 * Note that we can only assert this if the mirror node 1391 * is the source node's only parent. */ 1392 assert(!bdrv_get_dirty_count(op->s->dirty_bitmap)); 1393 } 1394 } 1395 bitmap_clear(op->s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1396 QTAILQ_REMOVE(&op->s->ops_in_flight, op, next); 1397 qemu_co_queue_restart_all(&op->waiting_requests); 1398 g_free(op); 1399 } 1400 1401 static int coroutine_fn bdrv_mirror_top_preadv(BlockDriverState *bs, 1402 int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags) 1403 { 1404 return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); 1405 } 1406 1407 static int coroutine_fn bdrv_mirror_top_do_write(BlockDriverState *bs, 1408 MirrorMethod method, uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, 1409 int flags) 1410 { 1411 MirrorOp *op = NULL; 1412 MirrorBDSOpaque *s = bs->opaque; 1413 int ret = 0; 1414 bool copy_to_target; 1415 1416 copy_to_target = s->job->ret >= 0 && 1417 !job_is_cancelled(&s->job->common.job) && 1418 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING; 1419 1420 if (copy_to_target) { 1421 op = active_write_prepare(s->job, offset, bytes); 1422 } 1423 1424 switch (method) { 1425 case MIRROR_METHOD_COPY: 1426 ret = bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags); 1427 break; 1428 1429 case MIRROR_METHOD_ZERO: 1430 ret = bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags); 1431 break; 1432 1433 case MIRROR_METHOD_DISCARD: 1434 ret = bdrv_co_pdiscard(bs->backing, offset, bytes); 1435 break; 1436 1437 default: 1438 abort(); 1439 } 1440 1441 if (ret < 0) { 1442 goto out; 1443 } 1444 1445 if (copy_to_target) { 1446 do_sync_target_write(s->job, method, offset, bytes, qiov, flags); 1447 } 1448 1449 out: 1450 if (copy_to_target) { 1451 active_write_settle(op); 1452 } 1453 return ret; 1454 } 1455 1456 static int coroutine_fn bdrv_mirror_top_pwritev(BlockDriverState *bs, 1457 int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags) 1458 { 1459 MirrorBDSOpaque *s = bs->opaque; 1460 QEMUIOVector bounce_qiov; 1461 void *bounce_buf; 1462 int ret = 0; 1463 bool copy_to_target; 1464 1465 copy_to_target = s->job->ret >= 0 && 1466 !job_is_cancelled(&s->job->common.job) && 1467 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING; 1468 1469 if (copy_to_target) { 1470 /* The guest might concurrently modify the data to write; but 1471 * the data on source and destination must match, so we have 1472 * to use a bounce buffer if we are going to write to the 1473 * target now. */ 1474 bounce_buf = qemu_blockalign(bs, bytes); 1475 iov_to_buf_full(qiov->iov, qiov->niov, 0, bounce_buf, bytes); 1476 1477 qemu_iovec_init(&bounce_qiov, 1); 1478 qemu_iovec_add(&bounce_qiov, bounce_buf, bytes); 1479 qiov = &bounce_qiov; 1480 } 1481 1482 ret = bdrv_mirror_top_do_write(bs, MIRROR_METHOD_COPY, offset, bytes, qiov, 1483 flags); 1484 1485 if (copy_to_target) { 1486 qemu_iovec_destroy(&bounce_qiov); 1487 qemu_vfree(bounce_buf); 1488 } 1489 1490 return ret; 1491 } 1492 1493 static int coroutine_fn bdrv_mirror_top_flush(BlockDriverState *bs) 1494 { 1495 if (bs->backing == NULL) { 1496 /* we can be here after failed bdrv_append in mirror_start_job */ 1497 return 0; 1498 } 1499 return bdrv_co_flush(bs->backing->bs); 1500 } 1501 1502 static int coroutine_fn bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs, 1503 int64_t offset, int64_t bytes, BdrvRequestFlags flags) 1504 { 1505 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_ZERO, offset, bytes, NULL, 1506 flags); 1507 } 1508 1509 static int coroutine_fn bdrv_mirror_top_pdiscard(BlockDriverState *bs, 1510 int64_t offset, int64_t bytes) 1511 { 1512 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_DISCARD, offset, bytes, 1513 NULL, 0); 1514 } 1515 1516 static void bdrv_mirror_top_refresh_filename(BlockDriverState *bs) 1517 { 1518 if (bs->backing == NULL) { 1519 /* we can be here after failed bdrv_attach_child in 1520 * bdrv_set_backing_hd */ 1521 return; 1522 } 1523 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), 1524 bs->backing->bs->filename); 1525 } 1526 1527 static void bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c, 1528 BdrvChildRole role, 1529 BlockReopenQueue *reopen_queue, 1530 uint64_t perm, uint64_t shared, 1531 uint64_t *nperm, uint64_t *nshared) 1532 { 1533 MirrorBDSOpaque *s = bs->opaque; 1534 1535 if (s->stop) { 1536 /* 1537 * If the job is to be stopped, we do not need to forward 1538 * anything to the real image. 1539 */ 1540 *nperm = 0; 1541 *nshared = BLK_PERM_ALL; 1542 return; 1543 } 1544 1545 bdrv_default_perms(bs, c, role, reopen_queue, 1546 perm, shared, nperm, nshared); 1547 1548 if (s->is_commit) { 1549 /* 1550 * For commit jobs, we cannot take CONSISTENT_READ, because 1551 * that permission is unshared for everything above the base 1552 * node (except for filters on the base node). 1553 * We also have to force-share the WRITE permission, or 1554 * otherwise we would block ourselves at the base node (if 1555 * writes are blocked for a node, they are also blocked for 1556 * its backing file). 1557 * (We could also share RESIZE, because it may be needed for 1558 * the target if its size is less than the top node's; but 1559 * bdrv_default_perms_for_cow() automatically shares RESIZE 1560 * for backing nodes if WRITE is shared, so there is no need 1561 * to do it here.) 1562 */ 1563 *nperm &= ~BLK_PERM_CONSISTENT_READ; 1564 *nshared |= BLK_PERM_WRITE; 1565 } 1566 } 1567 1568 /* Dummy node that provides consistent read to its users without requiring it 1569 * from its backing file and that allows writes on the backing file chain. */ 1570 static BlockDriver bdrv_mirror_top = { 1571 .format_name = "mirror_top", 1572 .bdrv_co_preadv = bdrv_mirror_top_preadv, 1573 .bdrv_co_pwritev = bdrv_mirror_top_pwritev, 1574 .bdrv_co_pwrite_zeroes = bdrv_mirror_top_pwrite_zeroes, 1575 .bdrv_co_pdiscard = bdrv_mirror_top_pdiscard, 1576 .bdrv_co_flush = bdrv_mirror_top_flush, 1577 .bdrv_refresh_filename = bdrv_mirror_top_refresh_filename, 1578 .bdrv_child_perm = bdrv_mirror_top_child_perm, 1579 1580 .is_filter = true, 1581 }; 1582 1583 static BlockJob *mirror_start_job( 1584 const char *job_id, BlockDriverState *bs, 1585 int creation_flags, BlockDriverState *target, 1586 const char *replaces, int64_t speed, 1587 uint32_t granularity, int64_t buf_size, 1588 BlockMirrorBackingMode backing_mode, 1589 bool zero_target, 1590 BlockdevOnError on_source_error, 1591 BlockdevOnError on_target_error, 1592 bool unmap, 1593 BlockCompletionFunc *cb, 1594 void *opaque, 1595 const BlockJobDriver *driver, 1596 bool is_none_mode, BlockDriverState *base, 1597 bool auto_complete, const char *filter_node_name, 1598 bool is_mirror, MirrorCopyMode copy_mode, 1599 Error **errp) 1600 { 1601 MirrorBlockJob *s; 1602 MirrorBDSOpaque *bs_opaque; 1603 BlockDriverState *mirror_top_bs; 1604 bool target_is_backing; 1605 uint64_t target_perms, target_shared_perms; 1606 int ret; 1607 1608 if (granularity == 0) { 1609 granularity = bdrv_get_default_bitmap_granularity(target); 1610 } 1611 1612 assert(is_power_of_2(granularity)); 1613 1614 if (buf_size < 0) { 1615 error_setg(errp, "Invalid parameter 'buf-size'"); 1616 return NULL; 1617 } 1618 1619 if (buf_size == 0) { 1620 buf_size = DEFAULT_MIRROR_BUF_SIZE; 1621 } 1622 1623 if (bdrv_skip_filters(bs) == bdrv_skip_filters(target)) { 1624 error_setg(errp, "Can't mirror node into itself"); 1625 return NULL; 1626 } 1627 1628 target_is_backing = bdrv_chain_contains(bs, target); 1629 1630 /* In the case of active commit, add dummy driver to provide consistent 1631 * reads on the top, while disabling it in the intermediate nodes, and make 1632 * the backing chain writable. */ 1633 mirror_top_bs = bdrv_new_open_driver(&bdrv_mirror_top, filter_node_name, 1634 BDRV_O_RDWR, errp); 1635 if (mirror_top_bs == NULL) { 1636 return NULL; 1637 } 1638 if (!filter_node_name) { 1639 mirror_top_bs->implicit = true; 1640 } 1641 1642 /* So that we can always drop this node */ 1643 mirror_top_bs->never_freeze = true; 1644 1645 mirror_top_bs->total_sectors = bs->total_sectors; 1646 mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED; 1647 mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED | 1648 BDRV_REQ_NO_FALLBACK; 1649 bs_opaque = g_new0(MirrorBDSOpaque, 1); 1650 mirror_top_bs->opaque = bs_opaque; 1651 1652 bs_opaque->is_commit = target_is_backing; 1653 1654 bdrv_drained_begin(bs); 1655 ret = bdrv_append(mirror_top_bs, bs, errp); 1656 bdrv_drained_end(bs); 1657 1658 if (ret < 0) { 1659 bdrv_unref(mirror_top_bs); 1660 return NULL; 1661 } 1662 1663 /* Make sure that the source is not resized while the job is running */ 1664 s = block_job_create(job_id, driver, NULL, mirror_top_bs, 1665 BLK_PERM_CONSISTENT_READ, 1666 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | 1667 BLK_PERM_WRITE, speed, 1668 creation_flags, cb, opaque, errp); 1669 if (!s) { 1670 goto fail; 1671 } 1672 bs_opaque->job = s; 1673 1674 /* The block job now has a reference to this node */ 1675 bdrv_unref(mirror_top_bs); 1676 1677 s->mirror_top_bs = mirror_top_bs; 1678 1679 /* No resize for the target either; while the mirror is still running, a 1680 * consistent read isn't necessarily possible. We could possibly allow 1681 * writes and graph modifications, though it would likely defeat the 1682 * purpose of a mirror, so leave them blocked for now. 1683 * 1684 * In the case of active commit, things look a bit different, though, 1685 * because the target is an already populated backing file in active use. 1686 * We can allow anything except resize there.*/ 1687 1688 target_perms = BLK_PERM_WRITE; 1689 target_shared_perms = BLK_PERM_WRITE_UNCHANGED; 1690 1691 if (target_is_backing) { 1692 int64_t bs_size, target_size; 1693 bs_size = bdrv_getlength(bs); 1694 if (bs_size < 0) { 1695 error_setg_errno(errp, -bs_size, 1696 "Could not inquire top image size"); 1697 goto fail; 1698 } 1699 1700 target_size = bdrv_getlength(target); 1701 if (target_size < 0) { 1702 error_setg_errno(errp, -target_size, 1703 "Could not inquire base image size"); 1704 goto fail; 1705 } 1706 1707 if (target_size < bs_size) { 1708 target_perms |= BLK_PERM_RESIZE; 1709 } 1710 1711 target_shared_perms |= BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE; 1712 } else if (bdrv_chain_contains(bs, bdrv_skip_filters(target))) { 1713 /* 1714 * We may want to allow this in the future, but it would 1715 * require taking some extra care. 1716 */ 1717 error_setg(errp, "Cannot mirror to a filter on top of a node in the " 1718 "source's backing chain"); 1719 goto fail; 1720 } 1721 1722 s->target = blk_new(s->common.job.aio_context, 1723 target_perms, target_shared_perms); 1724 ret = blk_insert_bs(s->target, target, errp); 1725 if (ret < 0) { 1726 goto fail; 1727 } 1728 if (is_mirror) { 1729 /* XXX: Mirror target could be a NBD server of target QEMU in the case 1730 * of non-shared block migration. To allow migration completion, we 1731 * have to allow "inactivate" of the target BB. When that happens, we 1732 * know the job is drained, and the vcpus are stopped, so no write 1733 * operation will be performed. Block layer already has assertions to 1734 * ensure that. */ 1735 blk_set_force_allow_inactivate(s->target); 1736 } 1737 blk_set_allow_aio_context_change(s->target, true); 1738 blk_set_disable_request_queuing(s->target, true); 1739 1740 s->replaces = g_strdup(replaces); 1741 s->on_source_error = on_source_error; 1742 s->on_target_error = on_target_error; 1743 s->is_none_mode = is_none_mode; 1744 s->backing_mode = backing_mode; 1745 s->zero_target = zero_target; 1746 s->copy_mode = copy_mode; 1747 s->base = base; 1748 s->base_overlay = bdrv_find_overlay(bs, base); 1749 s->granularity = granularity; 1750 s->buf_size = ROUND_UP(buf_size, granularity); 1751 s->unmap = unmap; 1752 if (auto_complete) { 1753 s->should_complete = true; 1754 } 1755 1756 s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp); 1757 if (!s->dirty_bitmap) { 1758 goto fail; 1759 } 1760 if (s->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING) { 1761 bdrv_disable_dirty_bitmap(s->dirty_bitmap); 1762 } 1763 1764 ret = block_job_add_bdrv(&s->common, "source", bs, 0, 1765 BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE | 1766 BLK_PERM_CONSISTENT_READ, 1767 errp); 1768 if (ret < 0) { 1769 goto fail; 1770 } 1771 1772 /* Required permissions are already taken with blk_new() */ 1773 block_job_add_bdrv(&s->common, "target", target, 0, BLK_PERM_ALL, 1774 &error_abort); 1775 1776 /* In commit_active_start() all intermediate nodes disappear, so 1777 * any jobs in them must be blocked */ 1778 if (target_is_backing) { 1779 BlockDriverState *iter, *filtered_target; 1780 uint64_t iter_shared_perms; 1781 1782 /* 1783 * The topmost node with 1784 * bdrv_skip_filters(filtered_target) == bdrv_skip_filters(target) 1785 */ 1786 filtered_target = bdrv_cow_bs(bdrv_find_overlay(bs, target)); 1787 1788 assert(bdrv_skip_filters(filtered_target) == 1789 bdrv_skip_filters(target)); 1790 1791 /* 1792 * XXX BLK_PERM_WRITE needs to be allowed so we don't block 1793 * ourselves at s->base (if writes are blocked for a node, they are 1794 * also blocked for its backing file). The other options would be a 1795 * second filter driver above s->base (== target). 1796 */ 1797 iter_shared_perms = BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE; 1798 1799 for (iter = bdrv_filter_or_cow_bs(bs); iter != target; 1800 iter = bdrv_filter_or_cow_bs(iter)) 1801 { 1802 if (iter == filtered_target) { 1803 /* 1804 * From here on, all nodes are filters on the base. 1805 * This allows us to share BLK_PERM_CONSISTENT_READ. 1806 */ 1807 iter_shared_perms |= BLK_PERM_CONSISTENT_READ; 1808 } 1809 1810 ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, 1811 iter_shared_perms, errp); 1812 if (ret < 0) { 1813 goto fail; 1814 } 1815 } 1816 1817 if (bdrv_freeze_backing_chain(mirror_top_bs, target, errp) < 0) { 1818 goto fail; 1819 } 1820 } 1821 1822 QTAILQ_INIT(&s->ops_in_flight); 1823 1824 trace_mirror_start(bs, s, opaque); 1825 job_start(&s->common.job); 1826 1827 return &s->common; 1828 1829 fail: 1830 if (s) { 1831 /* Make sure this BDS does not go away until we have completed the graph 1832 * changes below */ 1833 bdrv_ref(mirror_top_bs); 1834 1835 g_free(s->replaces); 1836 blk_unref(s->target); 1837 bs_opaque->job = NULL; 1838 if (s->dirty_bitmap) { 1839 bdrv_release_dirty_bitmap(s->dirty_bitmap); 1840 } 1841 job_early_fail(&s->common.job); 1842 } 1843 1844 bs_opaque->stop = true; 1845 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 1846 &error_abort); 1847 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort); 1848 1849 bdrv_unref(mirror_top_bs); 1850 1851 return NULL; 1852 } 1853 1854 void mirror_start(const char *job_id, BlockDriverState *bs, 1855 BlockDriverState *target, const char *replaces, 1856 int creation_flags, int64_t speed, 1857 uint32_t granularity, int64_t buf_size, 1858 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, 1859 bool zero_target, 1860 BlockdevOnError on_source_error, 1861 BlockdevOnError on_target_error, 1862 bool unmap, const char *filter_node_name, 1863 MirrorCopyMode copy_mode, Error **errp) 1864 { 1865 bool is_none_mode; 1866 BlockDriverState *base; 1867 1868 GLOBAL_STATE_CODE(); 1869 1870 if ((mode == MIRROR_SYNC_MODE_INCREMENTAL) || 1871 (mode == MIRROR_SYNC_MODE_BITMAP)) { 1872 error_setg(errp, "Sync mode '%s' not supported", 1873 MirrorSyncMode_str(mode)); 1874 return; 1875 } 1876 is_none_mode = mode == MIRROR_SYNC_MODE_NONE; 1877 base = mode == MIRROR_SYNC_MODE_TOP ? bdrv_backing_chain_next(bs) : NULL; 1878 mirror_start_job(job_id, bs, creation_flags, target, replaces, 1879 speed, granularity, buf_size, backing_mode, zero_target, 1880 on_source_error, on_target_error, unmap, NULL, NULL, 1881 &mirror_job_driver, is_none_mode, base, false, 1882 filter_node_name, true, copy_mode, errp); 1883 } 1884 1885 BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs, 1886 BlockDriverState *base, int creation_flags, 1887 int64_t speed, BlockdevOnError on_error, 1888 const char *filter_node_name, 1889 BlockCompletionFunc *cb, void *opaque, 1890 bool auto_complete, Error **errp) 1891 { 1892 bool base_read_only; 1893 BlockJob *job; 1894 1895 GLOBAL_STATE_CODE(); 1896 1897 base_read_only = bdrv_is_read_only(base); 1898 1899 if (base_read_only) { 1900 if (bdrv_reopen_set_read_only(base, false, errp) < 0) { 1901 return NULL; 1902 } 1903 } 1904 1905 job = mirror_start_job( 1906 job_id, bs, creation_flags, base, NULL, speed, 0, 0, 1907 MIRROR_LEAVE_BACKING_CHAIN, false, 1908 on_error, on_error, true, cb, opaque, 1909 &commit_active_job_driver, false, base, auto_complete, 1910 filter_node_name, false, MIRROR_COPY_MODE_BACKGROUND, 1911 errp); 1912 if (!job) { 1913 goto error_restore_flags; 1914 } 1915 1916 return job; 1917 1918 error_restore_flags: 1919 /* ignore error and errp for bdrv_reopen, because we want to propagate 1920 * the original error */ 1921 if (base_read_only) { 1922 bdrv_reopen_set_read_only(base, true, NULL); 1923 } 1924 return NULL; 1925 } 1926