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