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