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