1 /* 2 * Image mirroring 3 * 4 * Copyright Red Hat, Inc. 2012 5 * 6 * Authors: 7 * Paolo Bonzini <pbonzini@redhat.com> 8 * 9 * This work is licensed under the terms of the GNU LGPL, version 2 or later. 10 * See the COPYING.LIB file in the top-level directory. 11 * 12 */ 13 14 #include "qemu/osdep.h" 15 #include "qemu/cutils.h" 16 #include "qemu/coroutine.h" 17 #include "qemu/range.h" 18 #include "trace.h" 19 #include "block/blockjob_int.h" 20 #include "block/block_int.h" 21 #include "sysemu/block-backend.h" 22 #include "qapi/error.h" 23 #include "qapi/qmp/qerror.h" 24 #include "qemu/ratelimit.h" 25 #include "qemu/bitmap.h" 26 27 #define MAX_IN_FLIGHT 16 28 #define MAX_IO_BYTES (1 << 20) /* 1 Mb */ 29 #define DEFAULT_MIRROR_BUF_SIZE (MAX_IN_FLIGHT * MAX_IO_BYTES) 30 31 /* The mirroring buffer is a list of granularity-sized chunks. 32 * Free chunks are organized in a list. 33 */ 34 typedef struct MirrorBuffer { 35 QSIMPLEQ_ENTRY(MirrorBuffer) next; 36 } MirrorBuffer; 37 38 typedef struct MirrorOp MirrorOp; 39 40 typedef struct MirrorBlockJob { 41 BlockJob common; 42 BlockBackend *target; 43 BlockDriverState *mirror_top_bs; 44 BlockDriverState *base; 45 46 /* The name of the graph node to replace */ 47 char *replaces; 48 /* The BDS to replace */ 49 BlockDriverState *to_replace; 50 /* Used to block operations on the drive-mirror-replace target */ 51 Error *replace_blocker; 52 bool is_none_mode; 53 BlockMirrorBackingMode backing_mode; 54 /* Whether the target image requires explicit zero-initialization */ 55 bool zero_target; 56 MirrorCopyMode copy_mode; 57 BlockdevOnError on_source_error, on_target_error; 58 bool synced; 59 /* Set when the target is synced (dirty bitmap is clean, nothing 60 * in flight) and the job is running in active mode */ 61 bool actively_synced; 62 bool should_complete; 63 int64_t granularity; 64 size_t buf_size; 65 int64_t bdev_length; 66 unsigned long *cow_bitmap; 67 BdrvDirtyBitmap *dirty_bitmap; 68 BdrvDirtyBitmapIter *dbi; 69 uint8_t *buf; 70 QSIMPLEQ_HEAD(, MirrorBuffer) buf_free; 71 int buf_free_count; 72 73 uint64_t last_pause_ns; 74 unsigned long *in_flight_bitmap; 75 int in_flight; 76 int64_t bytes_in_flight; 77 QTAILQ_HEAD(, MirrorOp) ops_in_flight; 78 int ret; 79 bool unmap; 80 int target_cluster_size; 81 int max_iov; 82 bool initial_zeroing_ongoing; 83 int in_active_write_counter; 84 bool prepared; 85 bool in_drain; 86 } MirrorBlockJob; 87 88 typedef struct MirrorBDSOpaque { 89 MirrorBlockJob *job; 90 bool stop; 91 } MirrorBDSOpaque; 92 93 struct MirrorOp { 94 MirrorBlockJob *s; 95 QEMUIOVector qiov; 96 int64_t offset; 97 uint64_t bytes; 98 99 /* The pointee is set by mirror_co_read(), mirror_co_zero(), and 100 * mirror_co_discard() before yielding for the first time */ 101 int64_t *bytes_handled; 102 103 bool is_pseudo_op; 104 bool is_active_write; 105 CoQueue waiting_requests; 106 107 QTAILQ_ENTRY(MirrorOp) next; 108 }; 109 110 typedef enum MirrorMethod { 111 MIRROR_METHOD_COPY, 112 MIRROR_METHOD_ZERO, 113 MIRROR_METHOD_DISCARD, 114 } MirrorMethod; 115 116 static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, 117 int error) 118 { 119 s->synced = false; 120 s->actively_synced = false; 121 if (read) { 122 return block_job_error_action(&s->common, s->on_source_error, 123 true, error); 124 } else { 125 return block_job_error_action(&s->common, s->on_target_error, 126 false, error); 127 } 128 } 129 130 static void coroutine_fn mirror_wait_on_conflicts(MirrorOp *self, 131 MirrorBlockJob *s, 132 uint64_t offset, 133 uint64_t bytes) 134 { 135 uint64_t self_start_chunk = offset / s->granularity; 136 uint64_t self_end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 137 uint64_t self_nb_chunks = self_end_chunk - self_start_chunk; 138 139 while (find_next_bit(s->in_flight_bitmap, self_end_chunk, 140 self_start_chunk) < self_end_chunk && 141 s->ret >= 0) 142 { 143 MirrorOp *op; 144 145 QTAILQ_FOREACH(op, &s->ops_in_flight, next) { 146 uint64_t op_start_chunk = op->offset / s->granularity; 147 uint64_t op_nb_chunks = DIV_ROUND_UP(op->offset + op->bytes, 148 s->granularity) - 149 op_start_chunk; 150 151 if (op == self) { 152 continue; 153 } 154 155 if (ranges_overlap(self_start_chunk, self_nb_chunks, 156 op_start_chunk, op_nb_chunks)) 157 { 158 qemu_co_queue_wait(&op->waiting_requests, NULL); 159 break; 160 } 161 } 162 } 163 } 164 165 static void coroutine_fn mirror_iteration_done(MirrorOp *op, int ret) 166 { 167 MirrorBlockJob *s = op->s; 168 struct iovec *iov; 169 int64_t chunk_num; 170 int i, nb_chunks; 171 172 trace_mirror_iteration_done(s, op->offset, op->bytes, ret); 173 174 s->in_flight--; 175 s->bytes_in_flight -= op->bytes; 176 iov = op->qiov.iov; 177 for (i = 0; i < op->qiov.niov; i++) { 178 MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base; 179 QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next); 180 s->buf_free_count++; 181 } 182 183 chunk_num = op->offset / s->granularity; 184 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity); 185 186 bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks); 187 QTAILQ_REMOVE(&s->ops_in_flight, op, next); 188 if (ret >= 0) { 189 if (s->cow_bitmap) { 190 bitmap_set(s->cow_bitmap, chunk_num, nb_chunks); 191 } 192 if (!s->initial_zeroing_ongoing) { 193 job_progress_update(&s->common.job, op->bytes); 194 } 195 } 196 qemu_iovec_destroy(&op->qiov); 197 198 qemu_co_queue_restart_all(&op->waiting_requests); 199 g_free(op); 200 } 201 202 static void coroutine_fn mirror_write_complete(MirrorOp *op, int ret) 203 { 204 MirrorBlockJob *s = op->s; 205 206 if (ret < 0) { 207 BlockErrorAction action; 208 209 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes); 210 action = mirror_error_action(s, false, -ret); 211 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 212 s->ret = ret; 213 } 214 } 215 216 mirror_iteration_done(op, ret); 217 } 218 219 static void coroutine_fn mirror_read_complete(MirrorOp *op, int ret) 220 { 221 MirrorBlockJob *s = op->s; 222 223 if (ret < 0) { 224 BlockErrorAction action; 225 226 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes); 227 action = mirror_error_action(s, true, -ret); 228 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 229 s->ret = ret; 230 } 231 232 mirror_iteration_done(op, ret); 233 return; 234 } 235 236 ret = blk_co_pwritev(s->target, op->offset, op->qiov.size, &op->qiov, 0); 237 mirror_write_complete(op, ret); 238 } 239 240 /* Clip bytes relative to offset to not exceed end-of-file */ 241 static inline int64_t mirror_clip_bytes(MirrorBlockJob *s, 242 int64_t offset, 243 int64_t bytes) 244 { 245 return MIN(bytes, s->bdev_length - offset); 246 } 247 248 /* Round offset and/or bytes to target cluster if COW is needed, and 249 * return the offset of the adjusted tail against original. */ 250 static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset, 251 uint64_t *bytes) 252 { 253 bool need_cow; 254 int ret = 0; 255 int64_t align_offset = *offset; 256 int64_t align_bytes = *bytes; 257 int max_bytes = s->granularity * s->max_iov; 258 259 need_cow = !test_bit(*offset / s->granularity, s->cow_bitmap); 260 need_cow |= !test_bit((*offset + *bytes - 1) / s->granularity, 261 s->cow_bitmap); 262 if (need_cow) { 263 bdrv_round_to_clusters(blk_bs(s->target), *offset, *bytes, 264 &align_offset, &align_bytes); 265 } 266 267 if (align_bytes > max_bytes) { 268 align_bytes = max_bytes; 269 if (need_cow) { 270 align_bytes = QEMU_ALIGN_DOWN(align_bytes, s->target_cluster_size); 271 } 272 } 273 /* Clipping may result in align_bytes unaligned to chunk boundary, but 274 * that doesn't matter because it's already the end of source image. */ 275 align_bytes = mirror_clip_bytes(s, align_offset, align_bytes); 276 277 ret = align_offset + align_bytes - (*offset + *bytes); 278 *offset = align_offset; 279 *bytes = align_bytes; 280 assert(ret >= 0); 281 return ret; 282 } 283 284 static inline void coroutine_fn 285 mirror_wait_for_any_operation(MirrorBlockJob *s, bool active) 286 { 287 MirrorOp *op; 288 289 QTAILQ_FOREACH(op, &s->ops_in_flight, next) { 290 /* Do not wait on pseudo ops, because it may in turn wait on 291 * some other operation to start, which may in fact be the 292 * caller of this function. Since there is only one pseudo op 293 * at any given time, we will always find some real operation 294 * to wait on. */ 295 if (!op->is_pseudo_op && op->is_active_write == active) { 296 qemu_co_queue_wait(&op->waiting_requests, NULL); 297 return; 298 } 299 } 300 abort(); 301 } 302 303 static inline void coroutine_fn 304 mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s) 305 { 306 /* Only non-active operations use up in-flight slots */ 307 mirror_wait_for_any_operation(s, false); 308 } 309 310 /* Perform a mirror copy operation. 311 * 312 * *op->bytes_handled is set to the number of bytes copied after and 313 * including offset, excluding any bytes copied prior to offset due 314 * to alignment. This will be op->bytes if no alignment is necessary, 315 * or (new_end - op->offset) if the tail is rounded up or down due to 316 * alignment or buffer limit. 317 */ 318 static void coroutine_fn mirror_co_read(void *opaque) 319 { 320 MirrorOp *op = opaque; 321 MirrorBlockJob *s = op->s; 322 int nb_chunks; 323 uint64_t ret; 324 uint64_t max_bytes; 325 326 max_bytes = s->granularity * s->max_iov; 327 328 /* We can only handle as much as buf_size at a time. */ 329 op->bytes = MIN(s->buf_size, MIN(max_bytes, op->bytes)); 330 assert(op->bytes); 331 assert(op->bytes < BDRV_REQUEST_MAX_BYTES); 332 *op->bytes_handled = op->bytes; 333 334 if (s->cow_bitmap) { 335 *op->bytes_handled += mirror_cow_align(s, &op->offset, &op->bytes); 336 } 337 /* Cannot exceed BDRV_REQUEST_MAX_BYTES + INT_MAX */ 338 assert(*op->bytes_handled <= UINT_MAX); 339 assert(op->bytes <= s->buf_size); 340 /* The offset is granularity-aligned because: 341 * 1) Caller passes in aligned values; 342 * 2) mirror_cow_align is used only when target cluster is larger. */ 343 assert(QEMU_IS_ALIGNED(op->offset, s->granularity)); 344 /* The range is sector-aligned, since bdrv_getlength() rounds up. */ 345 assert(QEMU_IS_ALIGNED(op->bytes, BDRV_SECTOR_SIZE)); 346 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity); 347 348 while (s->buf_free_count < nb_chunks) { 349 trace_mirror_yield_in_flight(s, op->offset, s->in_flight); 350 mirror_wait_for_free_in_flight_slot(s); 351 } 352 353 /* Now make a QEMUIOVector taking enough granularity-sized chunks 354 * from s->buf_free. 355 */ 356 qemu_iovec_init(&op->qiov, nb_chunks); 357 while (nb_chunks-- > 0) { 358 MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free); 359 size_t remaining = op->bytes - op->qiov.size; 360 361 QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next); 362 s->buf_free_count--; 363 qemu_iovec_add(&op->qiov, buf, MIN(s->granularity, remaining)); 364 } 365 366 /* Copy the dirty cluster. */ 367 s->in_flight++; 368 s->bytes_in_flight += op->bytes; 369 trace_mirror_one_iteration(s, op->offset, op->bytes); 370 371 ret = bdrv_co_preadv(s->mirror_top_bs->backing, op->offset, op->bytes, 372 &op->qiov, 0); 373 mirror_read_complete(op, ret); 374 } 375 376 static void coroutine_fn mirror_co_zero(void *opaque) 377 { 378 MirrorOp *op = opaque; 379 int ret; 380 381 op->s->in_flight++; 382 op->s->bytes_in_flight += op->bytes; 383 *op->bytes_handled = op->bytes; 384 385 ret = blk_co_pwrite_zeroes(op->s->target, op->offset, op->bytes, 386 op->s->unmap ? BDRV_REQ_MAY_UNMAP : 0); 387 mirror_write_complete(op, ret); 388 } 389 390 static void coroutine_fn mirror_co_discard(void *opaque) 391 { 392 MirrorOp *op = opaque; 393 int ret; 394 395 op->s->in_flight++; 396 op->s->bytes_in_flight += op->bytes; 397 *op->bytes_handled = op->bytes; 398 399 ret = blk_co_pdiscard(op->s->target, op->offset, op->bytes); 400 mirror_write_complete(op, ret); 401 } 402 403 static unsigned mirror_perform(MirrorBlockJob *s, int64_t offset, 404 unsigned bytes, MirrorMethod mirror_method) 405 { 406 MirrorOp *op; 407 Coroutine *co; 408 int64_t bytes_handled = -1; 409 410 op = g_new(MirrorOp, 1); 411 *op = (MirrorOp){ 412 .s = s, 413 .offset = offset, 414 .bytes = bytes, 415 .bytes_handled = &bytes_handled, 416 }; 417 qemu_co_queue_init(&op->waiting_requests); 418 419 switch (mirror_method) { 420 case MIRROR_METHOD_COPY: 421 co = qemu_coroutine_create(mirror_co_read, op); 422 break; 423 case MIRROR_METHOD_ZERO: 424 co = qemu_coroutine_create(mirror_co_zero, op); 425 break; 426 case MIRROR_METHOD_DISCARD: 427 co = qemu_coroutine_create(mirror_co_discard, op); 428 break; 429 default: 430 abort(); 431 } 432 433 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 434 qemu_coroutine_enter(co); 435 /* At this point, ownership of op has been moved to the coroutine 436 * and the object may already be freed */ 437 438 /* Assert that this value has been set */ 439 assert(bytes_handled >= 0); 440 441 /* Same assertion as in mirror_co_read() (and for mirror_co_read() 442 * and mirror_co_discard(), bytes_handled == op->bytes, which 443 * is the @bytes parameter given to this function) */ 444 assert(bytes_handled <= UINT_MAX); 445 return bytes_handled; 446 } 447 448 static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) 449 { 450 BlockDriverState *source = s->mirror_top_bs->backing->bs; 451 MirrorOp *pseudo_op; 452 int64_t offset; 453 uint64_t delay_ns = 0, ret = 0; 454 /* At least the first dirty chunk is mirrored in one iteration. */ 455 int nb_chunks = 1; 456 bool write_zeroes_ok = bdrv_can_write_zeroes_with_unmap(blk_bs(s->target)); 457 int max_io_bytes = MAX(s->buf_size / MAX_IN_FLIGHT, MAX_IO_BYTES); 458 459 bdrv_dirty_bitmap_lock(s->dirty_bitmap); 460 offset = bdrv_dirty_iter_next(s->dbi); 461 if (offset < 0) { 462 bdrv_set_dirty_iter(s->dbi, 0); 463 offset = bdrv_dirty_iter_next(s->dbi); 464 trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap)); 465 assert(offset >= 0); 466 } 467 bdrv_dirty_bitmap_unlock(s->dirty_bitmap); 468 469 mirror_wait_on_conflicts(NULL, s, offset, 1); 470 471 job_pause_point(&s->common.job); 472 473 /* Find the number of consective dirty chunks following the first dirty 474 * one, and wait for in flight requests in them. */ 475 bdrv_dirty_bitmap_lock(s->dirty_bitmap); 476 while (nb_chunks * s->granularity < s->buf_size) { 477 int64_t next_dirty; 478 int64_t next_offset = offset + nb_chunks * s->granularity; 479 int64_t next_chunk = next_offset / s->granularity; 480 if (next_offset >= s->bdev_length || 481 !bdrv_dirty_bitmap_get_locked(s->dirty_bitmap, next_offset)) { 482 break; 483 } 484 if (test_bit(next_chunk, s->in_flight_bitmap)) { 485 break; 486 } 487 488 next_dirty = bdrv_dirty_iter_next(s->dbi); 489 if (next_dirty > next_offset || next_dirty < 0) { 490 /* The bitmap iterator's cache is stale, refresh it */ 491 bdrv_set_dirty_iter(s->dbi, next_offset); 492 next_dirty = bdrv_dirty_iter_next(s->dbi); 493 } 494 assert(next_dirty == next_offset); 495 nb_chunks++; 496 } 497 498 /* Clear dirty bits before querying the block status, because 499 * calling bdrv_block_status_above could yield - if some blocks are 500 * marked dirty in this window, we need to know. 501 */ 502 bdrv_reset_dirty_bitmap_locked(s->dirty_bitmap, offset, 503 nb_chunks * s->granularity); 504 bdrv_dirty_bitmap_unlock(s->dirty_bitmap); 505 506 /* Before claiming an area in the in-flight bitmap, we have to 507 * create a MirrorOp for it so that conflicting requests can wait 508 * for it. mirror_perform() will create the real MirrorOps later, 509 * for now we just create a pseudo operation that will wake up all 510 * conflicting requests once all real operations have been 511 * launched. */ 512 pseudo_op = g_new(MirrorOp, 1); 513 *pseudo_op = (MirrorOp){ 514 .offset = offset, 515 .bytes = nb_chunks * s->granularity, 516 .is_pseudo_op = true, 517 }; 518 qemu_co_queue_init(&pseudo_op->waiting_requests); 519 QTAILQ_INSERT_TAIL(&s->ops_in_flight, pseudo_op, next); 520 521 bitmap_set(s->in_flight_bitmap, offset / s->granularity, nb_chunks); 522 while (nb_chunks > 0 && offset < s->bdev_length) { 523 int ret; 524 int64_t io_bytes; 525 int64_t io_bytes_acct; 526 MirrorMethod mirror_method = MIRROR_METHOD_COPY; 527 528 assert(!(offset % s->granularity)); 529 ret = bdrv_block_status_above(source, NULL, offset, 530 nb_chunks * s->granularity, 531 &io_bytes, NULL, NULL); 532 if (ret < 0) { 533 io_bytes = MIN(nb_chunks * s->granularity, max_io_bytes); 534 } else if (ret & BDRV_BLOCK_DATA) { 535 io_bytes = MIN(io_bytes, max_io_bytes); 536 } 537 538 io_bytes -= io_bytes % s->granularity; 539 if (io_bytes < s->granularity) { 540 io_bytes = s->granularity; 541 } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) { 542 int64_t target_offset; 543 int64_t target_bytes; 544 bdrv_round_to_clusters(blk_bs(s->target), offset, io_bytes, 545 &target_offset, &target_bytes); 546 if (target_offset == offset && 547 target_bytes == io_bytes) { 548 mirror_method = ret & BDRV_BLOCK_ZERO ? 549 MIRROR_METHOD_ZERO : 550 MIRROR_METHOD_DISCARD; 551 } 552 } 553 554 while (s->in_flight >= MAX_IN_FLIGHT) { 555 trace_mirror_yield_in_flight(s, offset, s->in_flight); 556 mirror_wait_for_free_in_flight_slot(s); 557 } 558 559 if (s->ret < 0) { 560 ret = 0; 561 goto fail; 562 } 563 564 io_bytes = mirror_clip_bytes(s, offset, io_bytes); 565 io_bytes = mirror_perform(s, offset, io_bytes, mirror_method); 566 if (mirror_method != MIRROR_METHOD_COPY && write_zeroes_ok) { 567 io_bytes_acct = 0; 568 } else { 569 io_bytes_acct = io_bytes; 570 } 571 assert(io_bytes); 572 offset += io_bytes; 573 nb_chunks -= DIV_ROUND_UP(io_bytes, s->granularity); 574 delay_ns = block_job_ratelimit_get_delay(&s->common, io_bytes_acct); 575 } 576 577 ret = delay_ns; 578 fail: 579 QTAILQ_REMOVE(&s->ops_in_flight, pseudo_op, next); 580 qemu_co_queue_restart_all(&pseudo_op->waiting_requests); 581 g_free(pseudo_op); 582 583 return ret; 584 } 585 586 static void mirror_free_init(MirrorBlockJob *s) 587 { 588 int granularity = s->granularity; 589 size_t buf_size = s->buf_size; 590 uint8_t *buf = s->buf; 591 592 assert(s->buf_free_count == 0); 593 QSIMPLEQ_INIT(&s->buf_free); 594 while (buf_size != 0) { 595 MirrorBuffer *cur = (MirrorBuffer *)buf; 596 QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); 597 s->buf_free_count++; 598 buf_size -= granularity; 599 buf += granularity; 600 } 601 } 602 603 /* This is also used for the .pause callback. There is no matching 604 * mirror_resume() because mirror_run() will begin iterating again 605 * when the job is resumed. 606 */ 607 static void coroutine_fn mirror_wait_for_all_io(MirrorBlockJob *s) 608 { 609 while (s->in_flight > 0) { 610 mirror_wait_for_free_in_flight_slot(s); 611 } 612 } 613 614 /** 615 * mirror_exit_common: handle both abort() and prepare() cases. 616 * for .prepare, returns 0 on success and -errno on failure. 617 * for .abort cases, denoted by abort = true, MUST return 0. 618 */ 619 static int mirror_exit_common(Job *job) 620 { 621 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 622 BlockJob *bjob = &s->common; 623 MirrorBDSOpaque *bs_opaque = s->mirror_top_bs->opaque; 624 AioContext *replace_aio_context = NULL; 625 BlockDriverState *src = s->mirror_top_bs->backing->bs; 626 BlockDriverState *target_bs = blk_bs(s->target); 627 BlockDriverState *mirror_top_bs = s->mirror_top_bs; 628 Error *local_err = NULL; 629 bool abort = job->ret < 0; 630 int ret = 0; 631 632 if (s->prepared) { 633 return 0; 634 } 635 s->prepared = true; 636 637 if (bdrv_chain_contains(src, target_bs)) { 638 bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs); 639 } 640 641 bdrv_release_dirty_bitmap(src, s->dirty_bitmap); 642 643 /* Make sure that the source BDS doesn't go away during bdrv_replace_node, 644 * before we can call bdrv_drained_end */ 645 bdrv_ref(src); 646 bdrv_ref(mirror_top_bs); 647 bdrv_ref(target_bs); 648 649 /* 650 * Remove target parent that still uses BLK_PERM_WRITE/RESIZE before 651 * inserting target_bs at s->to_replace, where we might not be able to get 652 * these permissions. 653 */ 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. Not having 659 * these permissions any more means that we can't allow any new requests on 660 * mirror_top_bs from now on, so keep it drained. */ 661 bdrv_drained_begin(mirror_top_bs); 662 bs_opaque->stop = true; 663 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 664 &error_abort); 665 if (!abort && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { 666 BlockDriverState *backing = s->is_none_mode ? src : s->base; 667 if (backing_bs(target_bs) != backing) { 668 bdrv_set_backing_hd(target_bs, backing, &local_err); 669 if (local_err) { 670 error_report_err(local_err); 671 ret = -EPERM; 672 } 673 } 674 } 675 676 if (s->to_replace) { 677 replace_aio_context = bdrv_get_aio_context(s->to_replace); 678 aio_context_acquire(replace_aio_context); 679 } 680 681 if (s->should_complete && !abort) { 682 BlockDriverState *to_replace = s->to_replace ?: src; 683 bool ro = bdrv_is_read_only(to_replace); 684 685 if (ro != bdrv_is_read_only(target_bs)) { 686 bdrv_reopen_set_read_only(target_bs, ro, NULL); 687 } 688 689 /* The mirror job has no requests in flight any more, but we need to 690 * drain potential other users of the BDS before changing the graph. */ 691 assert(s->in_drain); 692 bdrv_drained_begin(target_bs); 693 bdrv_replace_node(to_replace, target_bs, &local_err); 694 bdrv_drained_end(target_bs); 695 if (local_err) { 696 error_report_err(local_err); 697 ret = -EPERM; 698 } 699 } 700 if (s->to_replace) { 701 bdrv_op_unblock_all(s->to_replace, s->replace_blocker); 702 error_free(s->replace_blocker); 703 bdrv_unref(s->to_replace); 704 } 705 if (replace_aio_context) { 706 aio_context_release(replace_aio_context); 707 } 708 g_free(s->replaces); 709 bdrv_unref(target_bs); 710 711 /* 712 * Remove the mirror filter driver from the graph. Before this, get rid of 713 * the blockers on the intermediate nodes so that the resulting state is 714 * valid. 715 */ 716 block_job_remove_all_bdrv(bjob); 717 bdrv_replace_node(mirror_top_bs, backing_bs(mirror_top_bs), &error_abort); 718 719 /* We just changed the BDS the job BB refers to (with either or both of the 720 * bdrv_replace_node() calls), so switch the BB back so the cleanup does 721 * the right thing. We don't need any permissions any more now. */ 722 blk_remove_bs(bjob->blk); 723 blk_set_perm(bjob->blk, 0, BLK_PERM_ALL, &error_abort); 724 blk_insert_bs(bjob->blk, mirror_top_bs, &error_abort); 725 726 bs_opaque->job = NULL; 727 728 bdrv_drained_end(src); 729 bdrv_drained_end(mirror_top_bs); 730 s->in_drain = false; 731 bdrv_unref(mirror_top_bs); 732 bdrv_unref(src); 733 734 return ret; 735 } 736 737 static int mirror_prepare(Job *job) 738 { 739 return mirror_exit_common(job); 740 } 741 742 static void mirror_abort(Job *job) 743 { 744 int ret = mirror_exit_common(job); 745 assert(ret == 0); 746 } 747 748 static void coroutine_fn mirror_throttle(MirrorBlockJob *s) 749 { 750 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 751 752 if (now - s->last_pause_ns > BLOCK_JOB_SLICE_TIME) { 753 s->last_pause_ns = now; 754 job_sleep_ns(&s->common.job, 0); 755 } else { 756 job_pause_point(&s->common.job); 757 } 758 } 759 760 static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) 761 { 762 int64_t offset; 763 BlockDriverState *base = s->base; 764 BlockDriverState *bs = s->mirror_top_bs->backing->bs; 765 BlockDriverState *target_bs = blk_bs(s->target); 766 int ret; 767 int64_t count; 768 769 if (s->zero_target) { 770 if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { 771 bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length); 772 return 0; 773 } 774 775 s->initial_zeroing_ongoing = true; 776 for (offset = 0; offset < s->bdev_length; ) { 777 int bytes = MIN(s->bdev_length - offset, 778 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 779 780 mirror_throttle(s); 781 782 if (job_is_cancelled(&s->common.job)) { 783 s->initial_zeroing_ongoing = false; 784 return 0; 785 } 786 787 if (s->in_flight >= MAX_IN_FLIGHT) { 788 trace_mirror_yield(s, UINT64_MAX, s->buf_free_count, 789 s->in_flight); 790 mirror_wait_for_free_in_flight_slot(s); 791 continue; 792 } 793 794 mirror_perform(s, offset, bytes, MIRROR_METHOD_ZERO); 795 offset += bytes; 796 } 797 798 mirror_wait_for_all_io(s); 799 s->initial_zeroing_ongoing = false; 800 } 801 802 /* First part, loop on the sectors and initialize the dirty bitmap. */ 803 for (offset = 0; offset < s->bdev_length; ) { 804 /* Just to make sure we are not exceeding int limit. */ 805 int bytes = MIN(s->bdev_length - offset, 806 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 807 808 mirror_throttle(s); 809 810 if (job_is_cancelled(&s->common.job)) { 811 return 0; 812 } 813 814 ret = bdrv_is_allocated_above(bs, base, false, offset, bytes, &count); 815 if (ret < 0) { 816 return ret; 817 } 818 819 assert(count); 820 if (ret == 1) { 821 bdrv_set_dirty_bitmap(s->dirty_bitmap, offset, count); 822 } 823 offset += count; 824 } 825 return 0; 826 } 827 828 /* Called when going out of the streaming phase to flush the bulk of the 829 * data to the medium, or just before completing. 830 */ 831 static int mirror_flush(MirrorBlockJob *s) 832 { 833 int ret = blk_flush(s->target); 834 if (ret < 0) { 835 if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) { 836 s->ret = ret; 837 } 838 } 839 return ret; 840 } 841 842 static int coroutine_fn mirror_run(Job *job, Error **errp) 843 { 844 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 845 BlockDriverState *bs = s->mirror_top_bs->backing->bs; 846 BlockDriverState *target_bs = blk_bs(s->target); 847 bool need_drain = true; 848 int64_t length; 849 BlockDriverInfo bdi; 850 char backing_filename[2]; /* we only need 2 characters because we are only 851 checking for a NULL string */ 852 int ret = 0; 853 854 if (job_is_cancelled(&s->common.job)) { 855 goto immediate_exit; 856 } 857 858 s->bdev_length = bdrv_getlength(bs); 859 if (s->bdev_length < 0) { 860 ret = s->bdev_length; 861 goto immediate_exit; 862 } 863 864 /* Active commit must resize the base image if its size differs from the 865 * active layer. */ 866 if (s->base == blk_bs(s->target)) { 867 int64_t base_length; 868 869 base_length = blk_getlength(s->target); 870 if (base_length < 0) { 871 ret = base_length; 872 goto immediate_exit; 873 } 874 875 if (s->bdev_length > base_length) { 876 ret = blk_truncate(s->target, s->bdev_length, PREALLOC_MODE_OFF, 877 NULL); 878 if (ret < 0) { 879 goto immediate_exit; 880 } 881 } 882 } 883 884 if (s->bdev_length == 0) { 885 /* Transition to the READY state and wait for complete. */ 886 job_transition_to_ready(&s->common.job); 887 s->synced = true; 888 s->actively_synced = true; 889 while (!job_is_cancelled(&s->common.job) && !s->should_complete) { 890 job_yield(&s->common.job); 891 } 892 s->common.job.cancelled = false; 893 goto immediate_exit; 894 } 895 896 length = DIV_ROUND_UP(s->bdev_length, s->granularity); 897 s->in_flight_bitmap = bitmap_new(length); 898 899 /* If we have no backing file yet in the destination, we cannot let 900 * the destination do COW. Instead, we copy sectors around the 901 * dirty data if needed. We need a bitmap to do that. 902 */ 903 bdrv_get_backing_filename(target_bs, backing_filename, 904 sizeof(backing_filename)); 905 if (!bdrv_get_info(target_bs, &bdi) && bdi.cluster_size) { 906 s->target_cluster_size = bdi.cluster_size; 907 } else { 908 s->target_cluster_size = BDRV_SECTOR_SIZE; 909 } 910 if (backing_filename[0] && !target_bs->backing && 911 s->granularity < s->target_cluster_size) { 912 s->buf_size = MAX(s->buf_size, s->target_cluster_size); 913 s->cow_bitmap = bitmap_new(length); 914 } 915 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); 916 917 s->buf = qemu_try_blockalign(bs, s->buf_size); 918 if (s->buf == NULL) { 919 ret = -ENOMEM; 920 goto immediate_exit; 921 } 922 923 mirror_free_init(s); 924 925 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 926 if (!s->is_none_mode) { 927 ret = mirror_dirty_init(s); 928 if (ret < 0 || job_is_cancelled(&s->common.job)) { 929 goto immediate_exit; 930 } 931 } 932 933 assert(!s->dbi); 934 s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap); 935 for (;;) { 936 uint64_t delay_ns = 0; 937 int64_t cnt, delta; 938 bool should_complete; 939 940 /* Do not start passive operations while there are active 941 * writes in progress */ 942 while (s->in_active_write_counter) { 943 mirror_wait_for_any_operation(s, true); 944 } 945 946 if (s->ret < 0) { 947 ret = s->ret; 948 goto immediate_exit; 949 } 950 951 job_pause_point(&s->common.job); 952 953 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 954 /* cnt is the number of dirty bytes remaining and s->bytes_in_flight is 955 * the number of bytes currently being processed; together those are 956 * the current remaining operation length */ 957 job_progress_set_remaining(&s->common.job, s->bytes_in_flight + cnt); 958 959 /* Note that even when no rate limit is applied we need to yield 960 * periodically with no pending I/O so that bdrv_drain_all() returns. 961 * We do so every BLKOCK_JOB_SLICE_TIME nanoseconds, or when there is 962 * an error, or when the source is clean, whichever comes first. */ 963 delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns; 964 if (delta < BLOCK_JOB_SLICE_TIME && 965 s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { 966 if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || 967 (cnt == 0 && s->in_flight > 0)) { 968 trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight); 969 mirror_wait_for_free_in_flight_slot(s); 970 continue; 971 } else if (cnt != 0) { 972 delay_ns = mirror_iteration(s); 973 } 974 } 975 976 should_complete = false; 977 if (s->in_flight == 0 && cnt == 0) { 978 trace_mirror_before_flush(s); 979 if (!s->synced) { 980 if (mirror_flush(s) < 0) { 981 /* Go check s->ret. */ 982 continue; 983 } 984 /* We're out of the streaming phase. From now on, if the job 985 * is cancelled we will actually complete all pending I/O and 986 * report completion. This way, block-job-cancel will leave 987 * the target in a consistent state. 988 */ 989 job_transition_to_ready(&s->common.job); 990 s->synced = true; 991 if (s->copy_mode != MIRROR_COPY_MODE_BACKGROUND) { 992 s->actively_synced = true; 993 } 994 } 995 996 should_complete = s->should_complete || 997 job_is_cancelled(&s->common.job); 998 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 999 } 1000 1001 if (cnt == 0 && should_complete) { 1002 /* The dirty bitmap is not updated while operations are pending. 1003 * If we're about to exit, wait for pending operations before 1004 * calling bdrv_get_dirty_count(bs), or we may exit while the 1005 * source has dirty data to copy! 1006 * 1007 * Note that I/O can be submitted by the guest while 1008 * mirror_populate runs, so pause it now. Before deciding 1009 * whether to switch to target check one last time if I/O has 1010 * come in the meanwhile, and if not flush the data to disk. 1011 */ 1012 trace_mirror_before_drain(s, cnt); 1013 1014 s->in_drain = true; 1015 bdrv_drained_begin(bs); 1016 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 1017 if (cnt > 0 || mirror_flush(s) < 0) { 1018 bdrv_drained_end(bs); 1019 s->in_drain = false; 1020 continue; 1021 } 1022 1023 /* The two disks are in sync. Exit and report successful 1024 * completion. 1025 */ 1026 assert(QLIST_EMPTY(&bs->tracked_requests)); 1027 s->common.job.cancelled = false; 1028 need_drain = false; 1029 break; 1030 } 1031 1032 ret = 0; 1033 1034 if (s->synced && !should_complete) { 1035 delay_ns = (s->in_flight == 0 && 1036 cnt == 0 ? BLOCK_JOB_SLICE_TIME : 0); 1037 } 1038 trace_mirror_before_sleep(s, cnt, s->synced, delay_ns); 1039 job_sleep_ns(&s->common.job, delay_ns); 1040 if (job_is_cancelled(&s->common.job) && 1041 (!s->synced || s->common.job.force_cancel)) 1042 { 1043 break; 1044 } 1045 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 1046 } 1047 1048 immediate_exit: 1049 if (s->in_flight > 0) { 1050 /* We get here only if something went wrong. Either the job failed, 1051 * or it was cancelled prematurely so that we do not guarantee that 1052 * the target is a copy of the source. 1053 */ 1054 assert(ret < 0 || ((s->common.job.force_cancel || !s->synced) && 1055 job_is_cancelled(&s->common.job))); 1056 assert(need_drain); 1057 mirror_wait_for_all_io(s); 1058 } 1059 1060 assert(s->in_flight == 0); 1061 qemu_vfree(s->buf); 1062 g_free(s->cow_bitmap); 1063 g_free(s->in_flight_bitmap); 1064 bdrv_dirty_iter_free(s->dbi); 1065 1066 if (need_drain) { 1067 s->in_drain = true; 1068 bdrv_drained_begin(bs); 1069 } 1070 1071 return ret; 1072 } 1073 1074 static void mirror_complete(Job *job, Error **errp) 1075 { 1076 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1077 BlockDriverState *target; 1078 1079 target = blk_bs(s->target); 1080 1081 if (!s->synced) { 1082 error_setg(errp, "The active block job '%s' cannot be completed", 1083 job->id); 1084 return; 1085 } 1086 1087 if (s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { 1088 int ret; 1089 1090 assert(!target->backing); 1091 ret = bdrv_open_backing_file(target, NULL, "backing", errp); 1092 if (ret < 0) { 1093 return; 1094 } 1095 } 1096 1097 /* block all operations on to_replace bs */ 1098 if (s->replaces) { 1099 AioContext *replace_aio_context; 1100 1101 s->to_replace = bdrv_find_node(s->replaces); 1102 if (!s->to_replace) { 1103 error_setg(errp, "Node name '%s' not found", s->replaces); 1104 return; 1105 } 1106 1107 replace_aio_context = bdrv_get_aio_context(s->to_replace); 1108 aio_context_acquire(replace_aio_context); 1109 1110 /* TODO Translate this into permission system. Current definition of 1111 * GRAPH_MOD would require to request it for the parents; they might 1112 * not even be BlockDriverStates, however, so a BdrvChild can't address 1113 * them. May need redefinition of GRAPH_MOD. */ 1114 error_setg(&s->replace_blocker, 1115 "block device is in use by block-job-complete"); 1116 bdrv_op_block_all(s->to_replace, s->replace_blocker); 1117 bdrv_ref(s->to_replace); 1118 1119 aio_context_release(replace_aio_context); 1120 } 1121 1122 s->should_complete = true; 1123 job_enter(job); 1124 } 1125 1126 static void coroutine_fn mirror_pause(Job *job) 1127 { 1128 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1129 1130 mirror_wait_for_all_io(s); 1131 } 1132 1133 static bool mirror_drained_poll(BlockJob *job) 1134 { 1135 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1136 1137 /* If the job isn't paused nor cancelled, we can't be sure that it won't 1138 * issue more requests. We make an exception if we've reached this point 1139 * from one of our own drain sections, to avoid a deadlock waiting for 1140 * ourselves. 1141 */ 1142 if (!s->common.job.paused && !s->common.job.cancelled && !s->in_drain) { 1143 return true; 1144 } 1145 1146 return !!s->in_flight; 1147 } 1148 1149 static const BlockJobDriver mirror_job_driver = { 1150 .job_driver = { 1151 .instance_size = sizeof(MirrorBlockJob), 1152 .job_type = JOB_TYPE_MIRROR, 1153 .free = block_job_free, 1154 .user_resume = block_job_user_resume, 1155 .run = mirror_run, 1156 .prepare = mirror_prepare, 1157 .abort = mirror_abort, 1158 .pause = mirror_pause, 1159 .complete = mirror_complete, 1160 }, 1161 .drained_poll = mirror_drained_poll, 1162 }; 1163 1164 static const BlockJobDriver commit_active_job_driver = { 1165 .job_driver = { 1166 .instance_size = sizeof(MirrorBlockJob), 1167 .job_type = JOB_TYPE_COMMIT, 1168 .free = block_job_free, 1169 .user_resume = block_job_user_resume, 1170 .run = mirror_run, 1171 .prepare = mirror_prepare, 1172 .abort = mirror_abort, 1173 .pause = mirror_pause, 1174 .complete = mirror_complete, 1175 }, 1176 .drained_poll = mirror_drained_poll, 1177 }; 1178 1179 static void coroutine_fn 1180 do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, 1181 uint64_t offset, uint64_t bytes, 1182 QEMUIOVector *qiov, int flags) 1183 { 1184 QEMUIOVector target_qiov; 1185 uint64_t dirty_offset = offset; 1186 uint64_t dirty_bytes; 1187 1188 if (qiov) { 1189 qemu_iovec_init(&target_qiov, qiov->niov); 1190 } 1191 1192 while (true) { 1193 bool valid_area; 1194 int ret; 1195 1196 bdrv_dirty_bitmap_lock(job->dirty_bitmap); 1197 dirty_bytes = MIN(offset + bytes - dirty_offset, INT_MAX); 1198 valid_area = bdrv_dirty_bitmap_next_dirty_area(job->dirty_bitmap, 1199 &dirty_offset, 1200 &dirty_bytes); 1201 if (!valid_area) { 1202 bdrv_dirty_bitmap_unlock(job->dirty_bitmap); 1203 break; 1204 } 1205 1206 bdrv_reset_dirty_bitmap_locked(job->dirty_bitmap, 1207 dirty_offset, dirty_bytes); 1208 bdrv_dirty_bitmap_unlock(job->dirty_bitmap); 1209 1210 job_progress_increase_remaining(&job->common.job, dirty_bytes); 1211 1212 assert(dirty_offset - offset <= SIZE_MAX); 1213 if (qiov) { 1214 qemu_iovec_reset(&target_qiov); 1215 qemu_iovec_concat(&target_qiov, qiov, 1216 dirty_offset - offset, dirty_bytes); 1217 } 1218 1219 switch (method) { 1220 case MIRROR_METHOD_COPY: 1221 ret = blk_co_pwritev(job->target, dirty_offset, dirty_bytes, 1222 qiov ? &target_qiov : NULL, flags); 1223 break; 1224 1225 case MIRROR_METHOD_ZERO: 1226 assert(!qiov); 1227 ret = blk_co_pwrite_zeroes(job->target, dirty_offset, dirty_bytes, 1228 flags); 1229 break; 1230 1231 case MIRROR_METHOD_DISCARD: 1232 assert(!qiov); 1233 ret = blk_co_pdiscard(job->target, dirty_offset, dirty_bytes); 1234 break; 1235 1236 default: 1237 abort(); 1238 } 1239 1240 if (ret >= 0) { 1241 job_progress_update(&job->common.job, dirty_bytes); 1242 } else { 1243 BlockErrorAction action; 1244 1245 bdrv_set_dirty_bitmap(job->dirty_bitmap, dirty_offset, dirty_bytes); 1246 job->actively_synced = false; 1247 1248 action = mirror_error_action(job, false, -ret); 1249 if (action == BLOCK_ERROR_ACTION_REPORT) { 1250 if (!job->ret) { 1251 job->ret = ret; 1252 } 1253 break; 1254 } 1255 } 1256 1257 dirty_offset += dirty_bytes; 1258 } 1259 1260 if (qiov) { 1261 qemu_iovec_destroy(&target_qiov); 1262 } 1263 } 1264 1265 static MirrorOp *coroutine_fn active_write_prepare(MirrorBlockJob *s, 1266 uint64_t offset, 1267 uint64_t bytes) 1268 { 1269 MirrorOp *op; 1270 uint64_t start_chunk = offset / s->granularity; 1271 uint64_t end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 1272 1273 op = g_new(MirrorOp, 1); 1274 *op = (MirrorOp){ 1275 .s = s, 1276 .offset = offset, 1277 .bytes = bytes, 1278 .is_active_write = true, 1279 }; 1280 qemu_co_queue_init(&op->waiting_requests); 1281 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 1282 1283 s->in_active_write_counter++; 1284 1285 mirror_wait_on_conflicts(op, s, offset, bytes); 1286 1287 bitmap_set(s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1288 1289 return op; 1290 } 1291 1292 static void coroutine_fn active_write_settle(MirrorOp *op) 1293 { 1294 uint64_t start_chunk = op->offset / op->s->granularity; 1295 uint64_t end_chunk = DIV_ROUND_UP(op->offset + op->bytes, 1296 op->s->granularity); 1297 1298 if (!--op->s->in_active_write_counter && op->s->actively_synced) { 1299 BdrvChild *source = op->s->mirror_top_bs->backing; 1300 1301 if (QLIST_FIRST(&source->bs->parents) == source && 1302 QLIST_NEXT(source, next_parent) == NULL) 1303 { 1304 /* Assert that we are back in sync once all active write 1305 * operations are settled. 1306 * Note that we can only assert this if the mirror node 1307 * is the source node's only parent. */ 1308 assert(!bdrv_get_dirty_count(op->s->dirty_bitmap)); 1309 } 1310 } 1311 bitmap_clear(op->s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1312 QTAILQ_REMOVE(&op->s->ops_in_flight, op, next); 1313 qemu_co_queue_restart_all(&op->waiting_requests); 1314 g_free(op); 1315 } 1316 1317 static int coroutine_fn bdrv_mirror_top_preadv(BlockDriverState *bs, 1318 uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) 1319 { 1320 return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); 1321 } 1322 1323 static int coroutine_fn bdrv_mirror_top_do_write(BlockDriverState *bs, 1324 MirrorMethod method, uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, 1325 int flags) 1326 { 1327 MirrorOp *op = NULL; 1328 MirrorBDSOpaque *s = bs->opaque; 1329 int ret = 0; 1330 bool copy_to_target; 1331 1332 copy_to_target = s->job->ret >= 0 && 1333 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING; 1334 1335 if (copy_to_target) { 1336 op = active_write_prepare(s->job, offset, bytes); 1337 } 1338 1339 switch (method) { 1340 case MIRROR_METHOD_COPY: 1341 ret = bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags); 1342 break; 1343 1344 case MIRROR_METHOD_ZERO: 1345 ret = bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags); 1346 break; 1347 1348 case MIRROR_METHOD_DISCARD: 1349 ret = bdrv_co_pdiscard(bs->backing, offset, bytes); 1350 break; 1351 1352 default: 1353 abort(); 1354 } 1355 1356 if (ret < 0) { 1357 goto out; 1358 } 1359 1360 if (copy_to_target) { 1361 do_sync_target_write(s->job, method, offset, bytes, qiov, flags); 1362 } 1363 1364 out: 1365 if (copy_to_target) { 1366 active_write_settle(op); 1367 } 1368 return ret; 1369 } 1370 1371 static int coroutine_fn bdrv_mirror_top_pwritev(BlockDriverState *bs, 1372 uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) 1373 { 1374 MirrorBDSOpaque *s = bs->opaque; 1375 QEMUIOVector bounce_qiov; 1376 void *bounce_buf; 1377 int ret = 0; 1378 bool copy_to_target; 1379 1380 copy_to_target = s->job->ret >= 0 && 1381 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING; 1382 1383 if (copy_to_target) { 1384 /* The guest might concurrently modify the data to write; but 1385 * the data on source and destination must match, so we have 1386 * to use a bounce buffer if we are going to write to the 1387 * target now. */ 1388 bounce_buf = qemu_blockalign(bs, bytes); 1389 iov_to_buf_full(qiov->iov, qiov->niov, 0, bounce_buf, bytes); 1390 1391 qemu_iovec_init(&bounce_qiov, 1); 1392 qemu_iovec_add(&bounce_qiov, bounce_buf, bytes); 1393 qiov = &bounce_qiov; 1394 } 1395 1396 ret = bdrv_mirror_top_do_write(bs, MIRROR_METHOD_COPY, offset, bytes, qiov, 1397 flags); 1398 1399 if (copy_to_target) { 1400 qemu_iovec_destroy(&bounce_qiov); 1401 qemu_vfree(bounce_buf); 1402 } 1403 1404 return ret; 1405 } 1406 1407 static int coroutine_fn bdrv_mirror_top_flush(BlockDriverState *bs) 1408 { 1409 if (bs->backing == NULL) { 1410 /* we can be here after failed bdrv_append in mirror_start_job */ 1411 return 0; 1412 } 1413 return bdrv_co_flush(bs->backing->bs); 1414 } 1415 1416 static int coroutine_fn bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs, 1417 int64_t offset, int bytes, BdrvRequestFlags flags) 1418 { 1419 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_ZERO, offset, bytes, NULL, 1420 flags); 1421 } 1422 1423 static int coroutine_fn bdrv_mirror_top_pdiscard(BlockDriverState *bs, 1424 int64_t offset, int bytes) 1425 { 1426 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_DISCARD, offset, bytes, 1427 NULL, 0); 1428 } 1429 1430 static void bdrv_mirror_top_refresh_filename(BlockDriverState *bs) 1431 { 1432 if (bs->backing == NULL) { 1433 /* we can be here after failed bdrv_attach_child in 1434 * bdrv_set_backing_hd */ 1435 return; 1436 } 1437 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), 1438 bs->backing->bs->filename); 1439 } 1440 1441 static void bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c, 1442 const BdrvChildRole *role, 1443 BlockReopenQueue *reopen_queue, 1444 uint64_t perm, uint64_t shared, 1445 uint64_t *nperm, uint64_t *nshared) 1446 { 1447 MirrorBDSOpaque *s = bs->opaque; 1448 1449 if (s->stop) { 1450 /* 1451 * If the job is to be stopped, we do not need to forward 1452 * anything to the real image. 1453 */ 1454 *nperm = 0; 1455 *nshared = BLK_PERM_ALL; 1456 return; 1457 } 1458 1459 /* Must be able to forward guest writes to the real image */ 1460 *nperm = 0; 1461 if (perm & BLK_PERM_WRITE) { 1462 *nperm |= BLK_PERM_WRITE; 1463 } 1464 1465 *nshared = BLK_PERM_ALL; 1466 } 1467 1468 static void bdrv_mirror_top_refresh_limits(BlockDriverState *bs, Error **errp) 1469 { 1470 MirrorBDSOpaque *s = bs->opaque; 1471 1472 if (s && s->job && s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING) { 1473 bs->bl.request_alignment = s->job->granularity; 1474 } 1475 } 1476 1477 /* Dummy node that provides consistent read to its users without requiring it 1478 * from its backing file and that allows writes on the backing file chain. */ 1479 static BlockDriver bdrv_mirror_top = { 1480 .format_name = "mirror_top", 1481 .bdrv_co_preadv = bdrv_mirror_top_preadv, 1482 .bdrv_co_pwritev = bdrv_mirror_top_pwritev, 1483 .bdrv_co_pwrite_zeroes = bdrv_mirror_top_pwrite_zeroes, 1484 .bdrv_co_pdiscard = bdrv_mirror_top_pdiscard, 1485 .bdrv_co_flush = bdrv_mirror_top_flush, 1486 .bdrv_co_block_status = bdrv_co_block_status_from_backing, 1487 .bdrv_refresh_filename = bdrv_mirror_top_refresh_filename, 1488 .bdrv_child_perm = bdrv_mirror_top_child_perm, 1489 .bdrv_refresh_limits = bdrv_mirror_top_refresh_limits, 1490 }; 1491 1492 static BlockJob *mirror_start_job( 1493 const char *job_id, BlockDriverState *bs, 1494 int creation_flags, BlockDriverState *target, 1495 const char *replaces, int64_t speed, 1496 uint32_t granularity, int64_t buf_size, 1497 BlockMirrorBackingMode backing_mode, 1498 bool zero_target, 1499 BlockdevOnError on_source_error, 1500 BlockdevOnError on_target_error, 1501 bool unmap, 1502 BlockCompletionFunc *cb, 1503 void *opaque, 1504 const BlockJobDriver *driver, 1505 bool is_none_mode, BlockDriverState *base, 1506 bool auto_complete, const char *filter_node_name, 1507 bool is_mirror, MirrorCopyMode copy_mode, 1508 Error **errp) 1509 { 1510 MirrorBlockJob *s; 1511 MirrorBDSOpaque *bs_opaque; 1512 BlockDriverState *mirror_top_bs; 1513 bool target_graph_mod; 1514 bool target_is_backing; 1515 Error *local_err = NULL; 1516 int ret; 1517 1518 if (granularity == 0) { 1519 granularity = bdrv_get_default_bitmap_granularity(target); 1520 } 1521 1522 assert(is_power_of_2(granularity)); 1523 1524 if (buf_size < 0) { 1525 error_setg(errp, "Invalid parameter 'buf-size'"); 1526 return NULL; 1527 } 1528 1529 if (buf_size == 0) { 1530 buf_size = DEFAULT_MIRROR_BUF_SIZE; 1531 } 1532 1533 if (bs == target) { 1534 error_setg(errp, "Can't mirror node into itself"); 1535 return NULL; 1536 } 1537 1538 /* In the case of active commit, add dummy driver to provide consistent 1539 * reads on the top, while disabling it in the intermediate nodes, and make 1540 * the backing chain writable. */ 1541 mirror_top_bs = bdrv_new_open_driver(&bdrv_mirror_top, filter_node_name, 1542 BDRV_O_RDWR, errp); 1543 if (mirror_top_bs == NULL) { 1544 return NULL; 1545 } 1546 if (!filter_node_name) { 1547 mirror_top_bs->implicit = true; 1548 } 1549 1550 /* So that we can always drop this node */ 1551 mirror_top_bs->never_freeze = true; 1552 1553 mirror_top_bs->total_sectors = bs->total_sectors; 1554 mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED; 1555 mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED | 1556 BDRV_REQ_NO_FALLBACK; 1557 bs_opaque = g_new0(MirrorBDSOpaque, 1); 1558 mirror_top_bs->opaque = bs_opaque; 1559 1560 /* bdrv_append takes ownership of the mirror_top_bs reference, need to keep 1561 * it alive until block_job_create() succeeds even if bs has no parent. */ 1562 bdrv_ref(mirror_top_bs); 1563 bdrv_drained_begin(bs); 1564 bdrv_append(mirror_top_bs, bs, &local_err); 1565 bdrv_drained_end(bs); 1566 1567 if (local_err) { 1568 bdrv_unref(mirror_top_bs); 1569 error_propagate(errp, local_err); 1570 return NULL; 1571 } 1572 1573 /* Make sure that the source is not resized while the job is running */ 1574 s = block_job_create(job_id, driver, NULL, mirror_top_bs, 1575 BLK_PERM_CONSISTENT_READ, 1576 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | 1577 BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD, speed, 1578 creation_flags, cb, opaque, errp); 1579 if (!s) { 1580 goto fail; 1581 } 1582 bs_opaque->job = s; 1583 1584 /* The block job now has a reference to this node */ 1585 bdrv_unref(mirror_top_bs); 1586 1587 s->mirror_top_bs = mirror_top_bs; 1588 1589 /* No resize for the target either; while the mirror is still running, a 1590 * consistent read isn't necessarily possible. We could possibly allow 1591 * writes and graph modifications, though it would likely defeat the 1592 * purpose of a mirror, so leave them blocked for now. 1593 * 1594 * In the case of active commit, things look a bit different, though, 1595 * because the target is an already populated backing file in active use. 1596 * We can allow anything except resize there.*/ 1597 target_is_backing = bdrv_chain_contains(bs, target); 1598 target_graph_mod = (backing_mode != MIRROR_LEAVE_BACKING_CHAIN); 1599 s->target = blk_new(s->common.job.aio_context, 1600 BLK_PERM_WRITE | BLK_PERM_RESIZE | 1601 (target_graph_mod ? BLK_PERM_GRAPH_MOD : 0), 1602 BLK_PERM_WRITE_UNCHANGED | 1603 (target_is_backing ? BLK_PERM_CONSISTENT_READ | 1604 BLK_PERM_WRITE | 1605 BLK_PERM_GRAPH_MOD : 0)); 1606 ret = blk_insert_bs(s->target, target, errp); 1607 if (ret < 0) { 1608 goto fail; 1609 } 1610 if (is_mirror) { 1611 /* XXX: Mirror target could be a NBD server of target QEMU in the case 1612 * of non-shared block migration. To allow migration completion, we 1613 * have to allow "inactivate" of the target BB. When that happens, we 1614 * know the job is drained, and the vcpus are stopped, so no write 1615 * operation will be performed. Block layer already has assertions to 1616 * ensure that. */ 1617 blk_set_force_allow_inactivate(s->target); 1618 } 1619 blk_set_allow_aio_context_change(s->target, true); 1620 blk_set_disable_request_queuing(s->target, true); 1621 1622 s->replaces = g_strdup(replaces); 1623 s->on_source_error = on_source_error; 1624 s->on_target_error = on_target_error; 1625 s->is_none_mode = is_none_mode; 1626 s->backing_mode = backing_mode; 1627 s->zero_target = zero_target; 1628 s->copy_mode = copy_mode; 1629 s->base = base; 1630 s->granularity = granularity; 1631 s->buf_size = ROUND_UP(buf_size, granularity); 1632 s->unmap = unmap; 1633 if (auto_complete) { 1634 s->should_complete = true; 1635 } 1636 1637 /* 1638 * Must be called before we start tracking writes, but after 1639 * 1640 * ((MirrorBlockJob *) 1641 * ((MirrorBDSOpaque *) 1642 * mirror_top_bs->opaque 1643 * )->job 1644 * )->copy_mode 1645 * 1646 * has the correct value. 1647 * (We start tracking writes as of the following 1648 * bdrv_create_dirty_bitmap() call.) 1649 */ 1650 bdrv_refresh_limits(mirror_top_bs, &local_err); 1651 if (local_err) { 1652 error_propagate(errp, local_err); 1653 goto fail; 1654 } 1655 1656 s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp); 1657 if (!s->dirty_bitmap) { 1658 goto fail; 1659 } 1660 1661 ret = block_job_add_bdrv(&s->common, "source", bs, 0, 1662 BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE | 1663 BLK_PERM_CONSISTENT_READ, 1664 errp); 1665 if (ret < 0) { 1666 goto fail; 1667 } 1668 1669 /* Required permissions are already taken with blk_new() */ 1670 block_job_add_bdrv(&s->common, "target", target, 0, BLK_PERM_ALL, 1671 &error_abort); 1672 1673 /* In commit_active_start() all intermediate nodes disappear, so 1674 * any jobs in them must be blocked */ 1675 if (target_is_backing) { 1676 BlockDriverState *iter; 1677 for (iter = backing_bs(bs); iter != target; iter = backing_bs(iter)) { 1678 /* XXX BLK_PERM_WRITE needs to be allowed so we don't block 1679 * ourselves at s->base (if writes are blocked for a node, they are 1680 * also blocked for its backing file). The other options would be a 1681 * second filter driver above s->base (== target). */ 1682 ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, 1683 BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE, 1684 errp); 1685 if (ret < 0) { 1686 goto fail; 1687 } 1688 } 1689 1690 if (bdrv_freeze_backing_chain(mirror_top_bs, target, errp) < 0) { 1691 goto fail; 1692 } 1693 } 1694 1695 QTAILQ_INIT(&s->ops_in_flight); 1696 1697 trace_mirror_start(bs, s, opaque); 1698 job_start(&s->common.job); 1699 1700 return &s->common; 1701 1702 fail: 1703 if (s) { 1704 /* Make sure this BDS does not go away until we have completed the graph 1705 * changes below */ 1706 bdrv_ref(mirror_top_bs); 1707 1708 g_free(s->replaces); 1709 blk_unref(s->target); 1710 bs_opaque->job = NULL; 1711 if (s->dirty_bitmap) { 1712 bdrv_release_dirty_bitmap(bs, s->dirty_bitmap); 1713 } 1714 job_early_fail(&s->common.job); 1715 } 1716 1717 bs_opaque->stop = true; 1718 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing, 1719 &error_abort); 1720 bdrv_replace_node(mirror_top_bs, backing_bs(mirror_top_bs), &error_abort); 1721 1722 bdrv_unref(mirror_top_bs); 1723 1724 return NULL; 1725 } 1726 1727 void mirror_start(const char *job_id, BlockDriverState *bs, 1728 BlockDriverState *target, const char *replaces, 1729 int creation_flags, int64_t speed, 1730 uint32_t granularity, int64_t buf_size, 1731 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, 1732 bool zero_target, 1733 BlockdevOnError on_source_error, 1734 BlockdevOnError on_target_error, 1735 bool unmap, const char *filter_node_name, 1736 MirrorCopyMode copy_mode, Error **errp) 1737 { 1738 bool is_none_mode; 1739 BlockDriverState *base; 1740 1741 if ((mode == MIRROR_SYNC_MODE_INCREMENTAL) || 1742 (mode == MIRROR_SYNC_MODE_BITMAP)) { 1743 error_setg(errp, "Sync mode '%s' not supported", 1744 MirrorSyncMode_str(mode)); 1745 return; 1746 } 1747 is_none_mode = mode == MIRROR_SYNC_MODE_NONE; 1748 base = mode == MIRROR_SYNC_MODE_TOP ? backing_bs(bs) : NULL; 1749 mirror_start_job(job_id, bs, creation_flags, target, replaces, 1750 speed, granularity, buf_size, backing_mode, zero_target, 1751 on_source_error, on_target_error, unmap, NULL, NULL, 1752 &mirror_job_driver, is_none_mode, base, false, 1753 filter_node_name, true, copy_mode, errp); 1754 } 1755 1756 BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs, 1757 BlockDriverState *base, int creation_flags, 1758 int64_t speed, BlockdevOnError on_error, 1759 const char *filter_node_name, 1760 BlockCompletionFunc *cb, void *opaque, 1761 bool auto_complete, Error **errp) 1762 { 1763 bool base_read_only; 1764 Error *local_err = NULL; 1765 BlockJob *ret; 1766 1767 base_read_only = bdrv_is_read_only(base); 1768 1769 if (base_read_only) { 1770 if (bdrv_reopen_set_read_only(base, false, errp) < 0) { 1771 return NULL; 1772 } 1773 } 1774 1775 ret = mirror_start_job( 1776 job_id, bs, creation_flags, base, NULL, speed, 0, 0, 1777 MIRROR_LEAVE_BACKING_CHAIN, false, 1778 on_error, on_error, true, cb, opaque, 1779 &commit_active_job_driver, false, base, auto_complete, 1780 filter_node_name, false, MIRROR_COPY_MODE_BACKGROUND, 1781 &local_err); 1782 if (local_err) { 1783 error_propagate(errp, local_err); 1784 goto error_restore_flags; 1785 } 1786 1787 return ret; 1788 1789 error_restore_flags: 1790 /* ignore error and errp for bdrv_reopen, because we want to propagate 1791 * the original error */ 1792 if (base_read_only) { 1793 bdrv_reopen_set_read_only(base, true, NULL); 1794 } 1795 return NULL; 1796 } 1797