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