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