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