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 } MirrorBlockJob; 83 84 typedef struct MirrorBDSOpaque { 85 MirrorBlockJob *job; 86 } MirrorBDSOpaque; 87 88 struct MirrorOp { 89 MirrorBlockJob *s; 90 QEMUIOVector qiov; 91 int64_t offset; 92 uint64_t bytes; 93 94 /* The pointee is set by mirror_co_read(), mirror_co_zero(), and 95 * mirror_co_discard() before yielding for the first time */ 96 int64_t *bytes_handled; 97 98 bool is_pseudo_op; 99 bool is_active_write; 100 CoQueue waiting_requests; 101 102 QTAILQ_ENTRY(MirrorOp) next; 103 }; 104 105 typedef enum MirrorMethod { 106 MIRROR_METHOD_COPY, 107 MIRROR_METHOD_ZERO, 108 MIRROR_METHOD_DISCARD, 109 } MirrorMethod; 110 111 static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, 112 int error) 113 { 114 s->synced = false; 115 s->actively_synced = false; 116 if (read) { 117 return block_job_error_action(&s->common, s->on_source_error, 118 true, error); 119 } else { 120 return block_job_error_action(&s->common, s->on_target_error, 121 false, error); 122 } 123 } 124 125 static void coroutine_fn mirror_wait_on_conflicts(MirrorOp *self, 126 MirrorBlockJob *s, 127 uint64_t offset, 128 uint64_t bytes) 129 { 130 uint64_t self_start_chunk = offset / s->granularity; 131 uint64_t self_end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 132 uint64_t self_nb_chunks = self_end_chunk - self_start_chunk; 133 134 while (find_next_bit(s->in_flight_bitmap, self_end_chunk, 135 self_start_chunk) < self_end_chunk && 136 s->ret >= 0) 137 { 138 MirrorOp *op; 139 140 QTAILQ_FOREACH(op, &s->ops_in_flight, next) { 141 uint64_t op_start_chunk = op->offset / s->granularity; 142 uint64_t op_nb_chunks = DIV_ROUND_UP(op->offset + op->bytes, 143 s->granularity) - 144 op_start_chunk; 145 146 if (op == self) { 147 continue; 148 } 149 150 if (ranges_overlap(self_start_chunk, self_nb_chunks, 151 op_start_chunk, op_nb_chunks)) 152 { 153 qemu_co_queue_wait(&op->waiting_requests, NULL); 154 break; 155 } 156 } 157 } 158 } 159 160 static void coroutine_fn mirror_iteration_done(MirrorOp *op, int ret) 161 { 162 MirrorBlockJob *s = op->s; 163 struct iovec *iov; 164 int64_t chunk_num; 165 int i, nb_chunks; 166 167 trace_mirror_iteration_done(s, op->offset, op->bytes, ret); 168 169 s->in_flight--; 170 s->bytes_in_flight -= op->bytes; 171 iov = op->qiov.iov; 172 for (i = 0; i < op->qiov.niov; i++) { 173 MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base; 174 QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next); 175 s->buf_free_count++; 176 } 177 178 chunk_num = op->offset / s->granularity; 179 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity); 180 181 bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks); 182 QTAILQ_REMOVE(&s->ops_in_flight, op, next); 183 if (ret >= 0) { 184 if (s->cow_bitmap) { 185 bitmap_set(s->cow_bitmap, chunk_num, nb_chunks); 186 } 187 if (!s->initial_zeroing_ongoing) { 188 job_progress_update(&s->common.job, op->bytes); 189 } 190 } 191 qemu_iovec_destroy(&op->qiov); 192 193 qemu_co_queue_restart_all(&op->waiting_requests); 194 g_free(op); 195 } 196 197 static void coroutine_fn mirror_write_complete(MirrorOp *op, int ret) 198 { 199 MirrorBlockJob *s = op->s; 200 201 aio_context_acquire(blk_get_aio_context(s->common.blk)); 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 mirror_iteration_done(op, ret); 212 aio_context_release(blk_get_aio_context(s->common.blk)); 213 } 214 215 static void coroutine_fn mirror_read_complete(MirrorOp *op, int ret) 216 { 217 MirrorBlockJob *s = op->s; 218 219 aio_context_acquire(blk_get_aio_context(s->common.blk)); 220 if (ret < 0) { 221 BlockErrorAction action; 222 223 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes); 224 action = mirror_error_action(s, true, -ret); 225 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) { 226 s->ret = ret; 227 } 228 229 mirror_iteration_done(op, ret); 230 } else { 231 ret = blk_co_pwritev(s->target, op->offset, 232 op->qiov.size, &op->qiov, 0); 233 mirror_write_complete(op, ret); 234 } 235 aio_context_release(blk_get_aio_context(s->common.blk)); 236 } 237 238 /* Clip bytes relative to offset to not exceed end-of-file */ 239 static inline int64_t mirror_clip_bytes(MirrorBlockJob *s, 240 int64_t offset, 241 int64_t bytes) 242 { 243 return MIN(bytes, s->bdev_length - offset); 244 } 245 246 /* Round offset and/or bytes to target cluster if COW is needed, and 247 * return the offset of the adjusted tail against original. */ 248 static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset, 249 uint64_t *bytes) 250 { 251 bool need_cow; 252 int ret = 0; 253 int64_t align_offset = *offset; 254 int64_t align_bytes = *bytes; 255 int max_bytes = s->granularity * s->max_iov; 256 257 need_cow = !test_bit(*offset / s->granularity, s->cow_bitmap); 258 need_cow |= !test_bit((*offset + *bytes - 1) / s->granularity, 259 s->cow_bitmap); 260 if (need_cow) { 261 bdrv_round_to_clusters(blk_bs(s->target), *offset, *bytes, 262 &align_offset, &align_bytes); 263 } 264 265 if (align_bytes > max_bytes) { 266 align_bytes = max_bytes; 267 if (need_cow) { 268 align_bytes = QEMU_ALIGN_DOWN(align_bytes, s->target_cluster_size); 269 } 270 } 271 /* Clipping may result in align_bytes unaligned to chunk boundary, but 272 * that doesn't matter because it's already the end of source image. */ 273 align_bytes = mirror_clip_bytes(s, align_offset, align_bytes); 274 275 ret = align_offset + align_bytes - (*offset + *bytes); 276 *offset = align_offset; 277 *bytes = align_bytes; 278 assert(ret >= 0); 279 return ret; 280 } 281 282 static inline void mirror_wait_for_any_operation(MirrorBlockJob *s, bool active) 283 { 284 MirrorOp *op; 285 286 QTAILQ_FOREACH(op, &s->ops_in_flight, next) { 287 /* Do not wait on pseudo ops, because it may in turn wait on 288 * some other operation to start, which may in fact be the 289 * caller of this function. Since there is only one pseudo op 290 * at any given time, we will always find some real operation 291 * to wait on. */ 292 if (!op->is_pseudo_op && op->is_active_write == active) { 293 qemu_co_queue_wait(&op->waiting_requests, NULL); 294 return; 295 } 296 } 297 abort(); 298 } 299 300 static inline void 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 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 typedef struct { 611 int ret; 612 } MirrorExitData; 613 614 static void mirror_exit(Job *job, void *opaque) 615 { 616 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 617 BlockJob *bjob = &s->common; 618 MirrorExitData *data = opaque; 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; 625 626 bdrv_release_dirty_bitmap(src, s->dirty_bitmap); 627 628 /* Make sure that the source BDS doesn't go away before we called 629 * job_completed(). */ 630 bdrv_ref(src); 631 bdrv_ref(mirror_top_bs); 632 bdrv_ref(target_bs); 633 634 /* Remove target parent that still uses BLK_PERM_WRITE/RESIZE before 635 * inserting target_bs at s->to_replace, where we might not be able to get 636 * these permissions. 637 * 638 * Note that blk_unref() alone doesn't necessarily drop permissions because 639 * we might be running nested inside mirror_drain(), which takes an extra 640 * reference, so use an explicit blk_set_perm() first. */ 641 blk_set_perm(s->target, 0, BLK_PERM_ALL, &error_abort); 642 blk_unref(s->target); 643 s->target = NULL; 644 645 /* We don't access the source any more. Dropping any WRITE/RESIZE is 646 * required before it could become a backing file of target_bs. */ 647 bdrv_child_try_set_perm(mirror_top_bs->backing, 0, BLK_PERM_ALL, 648 &error_abort); 649 if (s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) { 650 BlockDriverState *backing = s->is_none_mode ? src : s->base; 651 if (backing_bs(target_bs) != backing) { 652 bdrv_set_backing_hd(target_bs, backing, &local_err); 653 if (local_err) { 654 error_report_err(local_err); 655 data->ret = -EPERM; 656 } 657 } 658 } 659 660 if (s->to_replace) { 661 replace_aio_context = bdrv_get_aio_context(s->to_replace); 662 aio_context_acquire(replace_aio_context); 663 } 664 665 if (s->should_complete && data->ret == 0) { 666 BlockDriverState *to_replace = src; 667 if (s->to_replace) { 668 to_replace = s->to_replace; 669 } 670 671 if (bdrv_get_flags(target_bs) != bdrv_get_flags(to_replace)) { 672 bdrv_reopen(target_bs, bdrv_get_flags(to_replace), NULL); 673 } 674 675 /* The mirror job has no requests in flight any more, but we need to 676 * drain potential other users of the BDS before changing the graph. */ 677 bdrv_drained_begin(target_bs); 678 bdrv_replace_node(to_replace, target_bs, &local_err); 679 bdrv_drained_end(target_bs); 680 if (local_err) { 681 error_report_err(local_err); 682 data->ret = -EPERM; 683 } 684 } 685 if (s->to_replace) { 686 bdrv_op_unblock_all(s->to_replace, s->replace_blocker); 687 error_free(s->replace_blocker); 688 bdrv_unref(s->to_replace); 689 } 690 if (replace_aio_context) { 691 aio_context_release(replace_aio_context); 692 } 693 g_free(s->replaces); 694 bdrv_unref(target_bs); 695 696 /* Remove the mirror filter driver from the graph. Before this, get rid of 697 * the blockers on the intermediate nodes so that the resulting state is 698 * valid. Also give up permissions on mirror_top_bs->backing, which might 699 * block the removal. */ 700 block_job_remove_all_bdrv(bjob); 701 bdrv_child_try_set_perm(mirror_top_bs->backing, 0, BLK_PERM_ALL, 702 &error_abort); 703 bdrv_replace_node(mirror_top_bs, backing_bs(mirror_top_bs), &error_abort); 704 705 /* We just changed the BDS the job BB refers to (with either or both of the 706 * bdrv_replace_node() calls), so switch the BB back so the cleanup does 707 * the right thing. We don't need any permissions any more now. */ 708 blk_remove_bs(bjob->blk); 709 blk_set_perm(bjob->blk, 0, BLK_PERM_ALL, &error_abort); 710 blk_insert_bs(bjob->blk, mirror_top_bs, &error_abort); 711 712 bs_opaque->job = NULL; 713 job_completed(job, data->ret, NULL); 714 715 g_free(data); 716 bdrv_drained_end(src); 717 bdrv_unref(mirror_top_bs); 718 bdrv_unref(src); 719 } 720 721 static void mirror_throttle(MirrorBlockJob *s) 722 { 723 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 724 725 if (now - s->last_pause_ns > BLOCK_JOB_SLICE_TIME) { 726 s->last_pause_ns = now; 727 job_sleep_ns(&s->common.job, 0); 728 } else { 729 job_pause_point(&s->common.job); 730 } 731 } 732 733 static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) 734 { 735 int64_t offset; 736 BlockDriverState *base = s->base; 737 BlockDriverState *bs = s->mirror_top_bs->backing->bs; 738 BlockDriverState *target_bs = blk_bs(s->target); 739 int ret; 740 int64_t count; 741 742 if (base == NULL && !bdrv_has_zero_init(target_bs)) { 743 if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { 744 bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length); 745 return 0; 746 } 747 748 s->initial_zeroing_ongoing = true; 749 for (offset = 0; offset < s->bdev_length; ) { 750 int bytes = MIN(s->bdev_length - offset, 751 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 752 753 mirror_throttle(s); 754 755 if (job_is_cancelled(&s->common.job)) { 756 s->initial_zeroing_ongoing = false; 757 return 0; 758 } 759 760 if (s->in_flight >= MAX_IN_FLIGHT) { 761 trace_mirror_yield(s, UINT64_MAX, s->buf_free_count, 762 s->in_flight); 763 mirror_wait_for_free_in_flight_slot(s); 764 continue; 765 } 766 767 mirror_perform(s, offset, bytes, MIRROR_METHOD_ZERO); 768 offset += bytes; 769 } 770 771 mirror_wait_for_all_io(s); 772 s->initial_zeroing_ongoing = false; 773 } 774 775 /* First part, loop on the sectors and initialize the dirty bitmap. */ 776 for (offset = 0; offset < s->bdev_length; ) { 777 /* Just to make sure we are not exceeding int limit. */ 778 int bytes = MIN(s->bdev_length - offset, 779 QEMU_ALIGN_DOWN(INT_MAX, s->granularity)); 780 781 mirror_throttle(s); 782 783 if (job_is_cancelled(&s->common.job)) { 784 return 0; 785 } 786 787 ret = bdrv_is_allocated_above(bs, base, offset, bytes, &count); 788 if (ret < 0) { 789 return ret; 790 } 791 792 assert(count); 793 if (ret == 1) { 794 bdrv_set_dirty_bitmap(s->dirty_bitmap, offset, count); 795 } 796 offset += count; 797 } 798 return 0; 799 } 800 801 /* Called when going out of the streaming phase to flush the bulk of the 802 * data to the medium, or just before completing. 803 */ 804 static int mirror_flush(MirrorBlockJob *s) 805 { 806 int ret = blk_flush(s->target); 807 if (ret < 0) { 808 if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) { 809 s->ret = ret; 810 } 811 } 812 return ret; 813 } 814 815 static void coroutine_fn mirror_run(void *opaque) 816 { 817 MirrorBlockJob *s = opaque; 818 MirrorExitData *data; 819 BlockDriverState *bs = s->mirror_top_bs->backing->bs; 820 BlockDriverState *target_bs = blk_bs(s->target); 821 bool need_drain = true; 822 int64_t length; 823 BlockDriverInfo bdi; 824 char backing_filename[2]; /* we only need 2 characters because we are only 825 checking for a NULL string */ 826 int ret = 0; 827 828 if (job_is_cancelled(&s->common.job)) { 829 goto immediate_exit; 830 } 831 832 s->bdev_length = bdrv_getlength(bs); 833 if (s->bdev_length < 0) { 834 ret = s->bdev_length; 835 goto immediate_exit; 836 } 837 838 /* Active commit must resize the base image if its size differs from the 839 * active layer. */ 840 if (s->base == blk_bs(s->target)) { 841 int64_t base_length; 842 843 base_length = blk_getlength(s->target); 844 if (base_length < 0) { 845 ret = base_length; 846 goto immediate_exit; 847 } 848 849 if (s->bdev_length > base_length) { 850 ret = blk_truncate(s->target, s->bdev_length, PREALLOC_MODE_OFF, 851 NULL); 852 if (ret < 0) { 853 goto immediate_exit; 854 } 855 } 856 } 857 858 if (s->bdev_length == 0) { 859 /* Transition to the READY state and wait for complete. */ 860 job_transition_to_ready(&s->common.job); 861 s->synced = true; 862 s->actively_synced = true; 863 while (!job_is_cancelled(&s->common.job) && !s->should_complete) { 864 job_yield(&s->common.job); 865 } 866 s->common.job.cancelled = false; 867 goto immediate_exit; 868 } 869 870 length = DIV_ROUND_UP(s->bdev_length, s->granularity); 871 s->in_flight_bitmap = bitmap_new(length); 872 873 /* If we have no backing file yet in the destination, we cannot let 874 * the destination do COW. Instead, we copy sectors around the 875 * dirty data if needed. We need a bitmap to do that. 876 */ 877 bdrv_get_backing_filename(target_bs, backing_filename, 878 sizeof(backing_filename)); 879 if (!bdrv_get_info(target_bs, &bdi) && bdi.cluster_size) { 880 s->target_cluster_size = bdi.cluster_size; 881 } else { 882 s->target_cluster_size = BDRV_SECTOR_SIZE; 883 } 884 if (backing_filename[0] && !target_bs->backing && 885 s->granularity < s->target_cluster_size) { 886 s->buf_size = MAX(s->buf_size, s->target_cluster_size); 887 s->cow_bitmap = bitmap_new(length); 888 } 889 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov); 890 891 s->buf = qemu_try_blockalign(bs, s->buf_size); 892 if (s->buf == NULL) { 893 ret = -ENOMEM; 894 goto immediate_exit; 895 } 896 897 mirror_free_init(s); 898 899 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 900 if (!s->is_none_mode) { 901 ret = mirror_dirty_init(s); 902 if (ret < 0 || job_is_cancelled(&s->common.job)) { 903 goto immediate_exit; 904 } 905 } 906 907 assert(!s->dbi); 908 s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap); 909 for (;;) { 910 uint64_t delay_ns = 0; 911 int64_t cnt, delta; 912 bool should_complete; 913 914 /* Do not start passive operations while there are active 915 * writes in progress */ 916 while (s->in_active_write_counter) { 917 mirror_wait_for_any_operation(s, true); 918 } 919 920 if (s->ret < 0) { 921 ret = s->ret; 922 goto immediate_exit; 923 } 924 925 job_pause_point(&s->common.job); 926 927 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 928 /* cnt is the number of dirty bytes remaining and s->bytes_in_flight is 929 * the number of bytes currently being processed; together those are 930 * the current remaining operation length */ 931 job_progress_set_remaining(&s->common.job, s->bytes_in_flight + cnt); 932 933 /* Note that even when no rate limit is applied we need to yield 934 * periodically with no pending I/O so that bdrv_drain_all() returns. 935 * We do so every BLKOCK_JOB_SLICE_TIME nanoseconds, or when there is 936 * an error, or when the source is clean, whichever comes first. */ 937 delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns; 938 if (delta < BLOCK_JOB_SLICE_TIME && 939 s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { 940 if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || 941 (cnt == 0 && s->in_flight > 0)) { 942 trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight); 943 mirror_wait_for_free_in_flight_slot(s); 944 continue; 945 } else if (cnt != 0) { 946 delay_ns = mirror_iteration(s); 947 } 948 } 949 950 should_complete = false; 951 if (s->in_flight == 0 && cnt == 0) { 952 trace_mirror_before_flush(s); 953 if (!s->synced) { 954 if (mirror_flush(s) < 0) { 955 /* Go check s->ret. */ 956 continue; 957 } 958 /* We're out of the streaming phase. From now on, if the job 959 * is cancelled we will actually complete all pending I/O and 960 * report completion. This way, block-job-cancel will leave 961 * the target in a consistent state. 962 */ 963 job_transition_to_ready(&s->common.job); 964 s->synced = true; 965 if (s->copy_mode != MIRROR_COPY_MODE_BACKGROUND) { 966 s->actively_synced = true; 967 } 968 } 969 970 should_complete = s->should_complete || 971 job_is_cancelled(&s->common.job); 972 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 973 } 974 975 if (cnt == 0 && should_complete) { 976 /* The dirty bitmap is not updated while operations are pending. 977 * If we're about to exit, wait for pending operations before 978 * calling bdrv_get_dirty_count(bs), or we may exit while the 979 * source has dirty data to copy! 980 * 981 * Note that I/O can be submitted by the guest while 982 * mirror_populate runs, so pause it now. Before deciding 983 * whether to switch to target check one last time if I/O has 984 * come in the meanwhile, and if not flush the data to disk. 985 */ 986 trace_mirror_before_drain(s, cnt); 987 988 bdrv_drained_begin(bs); 989 cnt = bdrv_get_dirty_count(s->dirty_bitmap); 990 if (cnt > 0 || mirror_flush(s) < 0) { 991 bdrv_drained_end(bs); 992 continue; 993 } 994 995 /* The two disks are in sync. Exit and report successful 996 * completion. 997 */ 998 assert(QLIST_EMPTY(&bs->tracked_requests)); 999 s->common.job.cancelled = false; 1000 need_drain = false; 1001 break; 1002 } 1003 1004 ret = 0; 1005 1006 if (s->synced && !should_complete) { 1007 delay_ns = (s->in_flight == 0 && 1008 cnt == 0 ? BLOCK_JOB_SLICE_TIME : 0); 1009 } 1010 trace_mirror_before_sleep(s, cnt, s->synced, delay_ns); 1011 job_sleep_ns(&s->common.job, delay_ns); 1012 if (job_is_cancelled(&s->common.job) && 1013 (!s->synced || s->common.job.force_cancel)) 1014 { 1015 break; 1016 } 1017 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); 1018 } 1019 1020 immediate_exit: 1021 if (s->in_flight > 0) { 1022 /* We get here only if something went wrong. Either the job failed, 1023 * or it was cancelled prematurely so that we do not guarantee that 1024 * the target is a copy of the source. 1025 */ 1026 assert(ret < 0 || ((s->common.job.force_cancel || !s->synced) && 1027 job_is_cancelled(&s->common.job))); 1028 assert(need_drain); 1029 mirror_wait_for_all_io(s); 1030 } 1031 1032 assert(s->in_flight == 0); 1033 qemu_vfree(s->buf); 1034 g_free(s->cow_bitmap); 1035 g_free(s->in_flight_bitmap); 1036 bdrv_dirty_iter_free(s->dbi); 1037 1038 data = g_malloc(sizeof(*data)); 1039 data->ret = ret; 1040 1041 if (need_drain) { 1042 bdrv_drained_begin(bs); 1043 } 1044 job_defer_to_main_loop(&s->common.job, mirror_exit, data); 1045 } 1046 1047 static void mirror_complete(Job *job, Error **errp) 1048 { 1049 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1050 BlockDriverState *target; 1051 1052 target = blk_bs(s->target); 1053 1054 if (!s->synced) { 1055 error_setg(errp, "The active block job '%s' cannot be completed", 1056 job->id); 1057 return; 1058 } 1059 1060 if (s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) { 1061 int ret; 1062 1063 assert(!target->backing); 1064 ret = bdrv_open_backing_file(target, NULL, "backing", errp); 1065 if (ret < 0) { 1066 return; 1067 } 1068 } 1069 1070 /* block all operations on to_replace bs */ 1071 if (s->replaces) { 1072 AioContext *replace_aio_context; 1073 1074 s->to_replace = bdrv_find_node(s->replaces); 1075 if (!s->to_replace) { 1076 error_setg(errp, "Node name '%s' not found", s->replaces); 1077 return; 1078 } 1079 1080 replace_aio_context = bdrv_get_aio_context(s->to_replace); 1081 aio_context_acquire(replace_aio_context); 1082 1083 /* TODO Translate this into permission system. Current definition of 1084 * GRAPH_MOD would require to request it for the parents; they might 1085 * not even be BlockDriverStates, however, so a BdrvChild can't address 1086 * them. May need redefinition of GRAPH_MOD. */ 1087 error_setg(&s->replace_blocker, 1088 "block device is in use by block-job-complete"); 1089 bdrv_op_block_all(s->to_replace, s->replace_blocker); 1090 bdrv_ref(s->to_replace); 1091 1092 aio_context_release(replace_aio_context); 1093 } 1094 1095 s->should_complete = true; 1096 job_enter(job); 1097 } 1098 1099 static void mirror_pause(Job *job) 1100 { 1101 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job); 1102 1103 mirror_wait_for_all_io(s); 1104 } 1105 1106 static bool mirror_drained_poll(BlockJob *job) 1107 { 1108 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1109 return !!s->in_flight; 1110 } 1111 1112 static void mirror_attached_aio_context(BlockJob *job, AioContext *new_context) 1113 { 1114 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1115 1116 blk_set_aio_context(s->target, new_context); 1117 } 1118 1119 static void mirror_drain(BlockJob *job) 1120 { 1121 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); 1122 1123 /* Need to keep a reference in case blk_drain triggers execution 1124 * of mirror_complete... 1125 */ 1126 if (s->target) { 1127 BlockBackend *target = s->target; 1128 blk_ref(target); 1129 blk_drain(target); 1130 blk_unref(target); 1131 } 1132 } 1133 1134 static const BlockJobDriver mirror_job_driver = { 1135 .job_driver = { 1136 .instance_size = sizeof(MirrorBlockJob), 1137 .job_type = JOB_TYPE_MIRROR, 1138 .free = block_job_free, 1139 .user_resume = block_job_user_resume, 1140 .drain = block_job_drain, 1141 .start = mirror_run, 1142 .pause = mirror_pause, 1143 .complete = mirror_complete, 1144 }, 1145 .drained_poll = mirror_drained_poll, 1146 .attached_aio_context = mirror_attached_aio_context, 1147 .drain = mirror_drain, 1148 }; 1149 1150 static const BlockJobDriver commit_active_job_driver = { 1151 .job_driver = { 1152 .instance_size = sizeof(MirrorBlockJob), 1153 .job_type = JOB_TYPE_COMMIT, 1154 .free = block_job_free, 1155 .user_resume = block_job_user_resume, 1156 .drain = block_job_drain, 1157 .start = mirror_run, 1158 .pause = mirror_pause, 1159 .complete = mirror_complete, 1160 }, 1161 .drained_poll = mirror_drained_poll, 1162 .attached_aio_context = mirror_attached_aio_context, 1163 .drain = mirror_drain, 1164 }; 1165 1166 static void do_sync_target_write(MirrorBlockJob *job, MirrorMethod method, 1167 uint64_t offset, uint64_t bytes, 1168 QEMUIOVector *qiov, int flags) 1169 { 1170 BdrvDirtyBitmapIter *iter; 1171 QEMUIOVector target_qiov; 1172 uint64_t dirty_offset; 1173 int dirty_bytes; 1174 1175 if (qiov) { 1176 qemu_iovec_init(&target_qiov, qiov->niov); 1177 } 1178 1179 iter = bdrv_dirty_iter_new(job->dirty_bitmap); 1180 bdrv_set_dirty_iter(iter, offset); 1181 1182 while (true) { 1183 bool valid_area; 1184 int ret; 1185 1186 bdrv_dirty_bitmap_lock(job->dirty_bitmap); 1187 valid_area = bdrv_dirty_iter_next_area(iter, offset + bytes, 1188 &dirty_offset, &dirty_bytes); 1189 if (!valid_area) { 1190 bdrv_dirty_bitmap_unlock(job->dirty_bitmap); 1191 break; 1192 } 1193 1194 bdrv_reset_dirty_bitmap_locked(job->dirty_bitmap, 1195 dirty_offset, dirty_bytes); 1196 bdrv_dirty_bitmap_unlock(job->dirty_bitmap); 1197 1198 job_progress_increase_remaining(&job->common.job, dirty_bytes); 1199 1200 assert(dirty_offset - offset <= SIZE_MAX); 1201 if (qiov) { 1202 qemu_iovec_reset(&target_qiov); 1203 qemu_iovec_concat(&target_qiov, qiov, 1204 dirty_offset - offset, dirty_bytes); 1205 } 1206 1207 switch (method) { 1208 case MIRROR_METHOD_COPY: 1209 ret = blk_co_pwritev(job->target, dirty_offset, dirty_bytes, 1210 qiov ? &target_qiov : NULL, flags); 1211 break; 1212 1213 case MIRROR_METHOD_ZERO: 1214 assert(!qiov); 1215 ret = blk_co_pwrite_zeroes(job->target, dirty_offset, dirty_bytes, 1216 flags); 1217 break; 1218 1219 case MIRROR_METHOD_DISCARD: 1220 assert(!qiov); 1221 ret = blk_co_pdiscard(job->target, dirty_offset, dirty_bytes); 1222 break; 1223 1224 default: 1225 abort(); 1226 } 1227 1228 if (ret >= 0) { 1229 job_progress_update(&job->common.job, dirty_bytes); 1230 } else { 1231 BlockErrorAction action; 1232 1233 bdrv_set_dirty_bitmap(job->dirty_bitmap, dirty_offset, dirty_bytes); 1234 job->actively_synced = false; 1235 1236 action = mirror_error_action(job, false, -ret); 1237 if (action == BLOCK_ERROR_ACTION_REPORT) { 1238 if (!job->ret) { 1239 job->ret = ret; 1240 } 1241 break; 1242 } 1243 } 1244 } 1245 1246 bdrv_dirty_iter_free(iter); 1247 if (qiov) { 1248 qemu_iovec_destroy(&target_qiov); 1249 } 1250 } 1251 1252 static MirrorOp *coroutine_fn active_write_prepare(MirrorBlockJob *s, 1253 uint64_t offset, 1254 uint64_t bytes) 1255 { 1256 MirrorOp *op; 1257 uint64_t start_chunk = offset / s->granularity; 1258 uint64_t end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity); 1259 1260 op = g_new(MirrorOp, 1); 1261 *op = (MirrorOp){ 1262 .s = s, 1263 .offset = offset, 1264 .bytes = bytes, 1265 .is_active_write = true, 1266 }; 1267 qemu_co_queue_init(&op->waiting_requests); 1268 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next); 1269 1270 s->in_active_write_counter++; 1271 1272 mirror_wait_on_conflicts(op, s, offset, bytes); 1273 1274 bitmap_set(s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1275 1276 return op; 1277 } 1278 1279 static void coroutine_fn active_write_settle(MirrorOp *op) 1280 { 1281 uint64_t start_chunk = op->offset / op->s->granularity; 1282 uint64_t end_chunk = DIV_ROUND_UP(op->offset + op->bytes, 1283 op->s->granularity); 1284 1285 if (!--op->s->in_active_write_counter && op->s->actively_synced) { 1286 BdrvChild *source = op->s->mirror_top_bs->backing; 1287 1288 if (QLIST_FIRST(&source->bs->parents) == source && 1289 QLIST_NEXT(source, next_parent) == NULL) 1290 { 1291 /* Assert that we are back in sync once all active write 1292 * operations are settled. 1293 * Note that we can only assert this if the mirror node 1294 * is the source node's only parent. */ 1295 assert(!bdrv_get_dirty_count(op->s->dirty_bitmap)); 1296 } 1297 } 1298 bitmap_clear(op->s->in_flight_bitmap, start_chunk, end_chunk - start_chunk); 1299 QTAILQ_REMOVE(&op->s->ops_in_flight, op, next); 1300 qemu_co_queue_restart_all(&op->waiting_requests); 1301 g_free(op); 1302 } 1303 1304 static int coroutine_fn bdrv_mirror_top_preadv(BlockDriverState *bs, 1305 uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) 1306 { 1307 return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); 1308 } 1309 1310 static int coroutine_fn bdrv_mirror_top_do_write(BlockDriverState *bs, 1311 MirrorMethod method, uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, 1312 int flags) 1313 { 1314 MirrorOp *op = NULL; 1315 MirrorBDSOpaque *s = bs->opaque; 1316 int ret = 0; 1317 bool copy_to_target; 1318 1319 copy_to_target = s->job->ret >= 0 && 1320 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING; 1321 1322 if (copy_to_target) { 1323 op = active_write_prepare(s->job, offset, bytes); 1324 } 1325 1326 switch (method) { 1327 case MIRROR_METHOD_COPY: 1328 ret = bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags); 1329 break; 1330 1331 case MIRROR_METHOD_ZERO: 1332 ret = bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags); 1333 break; 1334 1335 case MIRROR_METHOD_DISCARD: 1336 ret = bdrv_co_pdiscard(bs->backing, offset, bytes); 1337 break; 1338 1339 default: 1340 abort(); 1341 } 1342 1343 if (ret < 0) { 1344 goto out; 1345 } 1346 1347 if (copy_to_target) { 1348 do_sync_target_write(s->job, method, offset, bytes, qiov, flags); 1349 } 1350 1351 out: 1352 if (copy_to_target) { 1353 active_write_settle(op); 1354 } 1355 return ret; 1356 } 1357 1358 static int coroutine_fn bdrv_mirror_top_pwritev(BlockDriverState *bs, 1359 uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags) 1360 { 1361 MirrorBDSOpaque *s = bs->opaque; 1362 QEMUIOVector bounce_qiov; 1363 void *bounce_buf; 1364 int ret = 0; 1365 bool copy_to_target; 1366 1367 copy_to_target = s->job->ret >= 0 && 1368 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING; 1369 1370 if (copy_to_target) { 1371 /* The guest might concurrently modify the data to write; but 1372 * the data on source and destination must match, so we have 1373 * to use a bounce buffer if we are going to write to the 1374 * target now. */ 1375 bounce_buf = qemu_blockalign(bs, bytes); 1376 iov_to_buf_full(qiov->iov, qiov->niov, 0, bounce_buf, bytes); 1377 1378 qemu_iovec_init(&bounce_qiov, 1); 1379 qemu_iovec_add(&bounce_qiov, bounce_buf, bytes); 1380 qiov = &bounce_qiov; 1381 } 1382 1383 ret = bdrv_mirror_top_do_write(bs, MIRROR_METHOD_COPY, offset, bytes, qiov, 1384 flags); 1385 1386 if (copy_to_target) { 1387 qemu_iovec_destroy(&bounce_qiov); 1388 qemu_vfree(bounce_buf); 1389 } 1390 1391 return ret; 1392 } 1393 1394 static int coroutine_fn bdrv_mirror_top_flush(BlockDriverState *bs) 1395 { 1396 if (bs->backing == NULL) { 1397 /* we can be here after failed bdrv_append in mirror_start_job */ 1398 return 0; 1399 } 1400 return bdrv_co_flush(bs->backing->bs); 1401 } 1402 1403 static int coroutine_fn bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs, 1404 int64_t offset, int bytes, BdrvRequestFlags flags) 1405 { 1406 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_ZERO, offset, bytes, NULL, 1407 flags); 1408 } 1409 1410 static int coroutine_fn bdrv_mirror_top_pdiscard(BlockDriverState *bs, 1411 int64_t offset, int bytes) 1412 { 1413 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_DISCARD, offset, bytes, 1414 NULL, 0); 1415 } 1416 1417 static void bdrv_mirror_top_refresh_filename(BlockDriverState *bs, QDict *opts) 1418 { 1419 if (bs->backing == NULL) { 1420 /* we can be here after failed bdrv_attach_child in 1421 * bdrv_set_backing_hd */ 1422 return; 1423 } 1424 bdrv_refresh_filename(bs->backing->bs); 1425 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), 1426 bs->backing->bs->filename); 1427 } 1428 1429 static void bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c, 1430 const BdrvChildRole *role, 1431 BlockReopenQueue *reopen_queue, 1432 uint64_t perm, uint64_t shared, 1433 uint64_t *nperm, uint64_t *nshared) 1434 { 1435 /* Must be able to forward guest writes to the real image */ 1436 *nperm = 0; 1437 if (perm & BLK_PERM_WRITE) { 1438 *nperm |= BLK_PERM_WRITE; 1439 } 1440 1441 *nshared = BLK_PERM_ALL; 1442 } 1443 1444 /* Dummy node that provides consistent read to its users without requiring it 1445 * from its backing file and that allows writes on the backing file chain. */ 1446 static BlockDriver bdrv_mirror_top = { 1447 .format_name = "mirror_top", 1448 .bdrv_co_preadv = bdrv_mirror_top_preadv, 1449 .bdrv_co_pwritev = bdrv_mirror_top_pwritev, 1450 .bdrv_co_pwrite_zeroes = bdrv_mirror_top_pwrite_zeroes, 1451 .bdrv_co_pdiscard = bdrv_mirror_top_pdiscard, 1452 .bdrv_co_flush = bdrv_mirror_top_flush, 1453 .bdrv_co_block_status = bdrv_co_block_status_from_backing, 1454 .bdrv_refresh_filename = bdrv_mirror_top_refresh_filename, 1455 .bdrv_child_perm = bdrv_mirror_top_child_perm, 1456 }; 1457 1458 static void mirror_start_job(const char *job_id, BlockDriverState *bs, 1459 int creation_flags, BlockDriverState *target, 1460 const char *replaces, int64_t speed, 1461 uint32_t granularity, int64_t buf_size, 1462 BlockMirrorBackingMode backing_mode, 1463 BlockdevOnError on_source_error, 1464 BlockdevOnError on_target_error, 1465 bool unmap, 1466 BlockCompletionFunc *cb, 1467 void *opaque, 1468 const BlockJobDriver *driver, 1469 bool is_none_mode, BlockDriverState *base, 1470 bool auto_complete, const char *filter_node_name, 1471 bool is_mirror, MirrorCopyMode copy_mode, 1472 Error **errp) 1473 { 1474 MirrorBlockJob *s; 1475 MirrorBDSOpaque *bs_opaque; 1476 BlockDriverState *mirror_top_bs; 1477 bool target_graph_mod; 1478 bool target_is_backing; 1479 Error *local_err = NULL; 1480 int ret; 1481 1482 if (granularity == 0) { 1483 granularity = bdrv_get_default_bitmap_granularity(target); 1484 } 1485 1486 assert(is_power_of_2(granularity)); 1487 1488 if (buf_size < 0) { 1489 error_setg(errp, "Invalid parameter 'buf-size'"); 1490 return; 1491 } 1492 1493 if (buf_size == 0) { 1494 buf_size = DEFAULT_MIRROR_BUF_SIZE; 1495 } 1496 1497 if (bs == target) { 1498 error_setg(errp, "Can't mirror node into itself"); 1499 return; 1500 } 1501 1502 /* In the case of active commit, add dummy driver to provide consistent 1503 * reads on the top, while disabling it in the intermediate nodes, and make 1504 * the backing chain writable. */ 1505 mirror_top_bs = bdrv_new_open_driver(&bdrv_mirror_top, filter_node_name, 1506 BDRV_O_RDWR, errp); 1507 if (mirror_top_bs == NULL) { 1508 return; 1509 } 1510 if (!filter_node_name) { 1511 mirror_top_bs->implicit = true; 1512 } 1513 mirror_top_bs->total_sectors = bs->total_sectors; 1514 mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED; 1515 mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED; 1516 bs_opaque = g_new0(MirrorBDSOpaque, 1); 1517 mirror_top_bs->opaque = bs_opaque; 1518 bdrv_set_aio_context(mirror_top_bs, bdrv_get_aio_context(bs)); 1519 1520 /* bdrv_append takes ownership of the mirror_top_bs reference, need to keep 1521 * it alive until block_job_create() succeeds even if bs has no parent. */ 1522 bdrv_ref(mirror_top_bs); 1523 bdrv_drained_begin(bs); 1524 bdrv_append(mirror_top_bs, bs, &local_err); 1525 bdrv_drained_end(bs); 1526 1527 if (local_err) { 1528 bdrv_unref(mirror_top_bs); 1529 error_propagate(errp, local_err); 1530 return; 1531 } 1532 1533 /* Make sure that the source is not resized while the job is running */ 1534 s = block_job_create(job_id, driver, NULL, mirror_top_bs, 1535 BLK_PERM_CONSISTENT_READ, 1536 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED | 1537 BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD, speed, 1538 creation_flags, cb, opaque, errp); 1539 if (!s) { 1540 goto fail; 1541 } 1542 bs_opaque->job = s; 1543 1544 /* The block job now has a reference to this node */ 1545 bdrv_unref(mirror_top_bs); 1546 1547 s->mirror_top_bs = mirror_top_bs; 1548 1549 /* No resize for the target either; while the mirror is still running, a 1550 * consistent read isn't necessarily possible. We could possibly allow 1551 * writes and graph modifications, though it would likely defeat the 1552 * purpose of a mirror, so leave them blocked for now. 1553 * 1554 * In the case of active commit, things look a bit different, though, 1555 * because the target is an already populated backing file in active use. 1556 * We can allow anything except resize there.*/ 1557 target_is_backing = bdrv_chain_contains(bs, target); 1558 target_graph_mod = (backing_mode != MIRROR_LEAVE_BACKING_CHAIN); 1559 s->target = blk_new(BLK_PERM_WRITE | BLK_PERM_RESIZE | 1560 (target_graph_mod ? BLK_PERM_GRAPH_MOD : 0), 1561 BLK_PERM_WRITE_UNCHANGED | 1562 (target_is_backing ? BLK_PERM_CONSISTENT_READ | 1563 BLK_PERM_WRITE | 1564 BLK_PERM_GRAPH_MOD : 0)); 1565 ret = blk_insert_bs(s->target, target, errp); 1566 if (ret < 0) { 1567 goto fail; 1568 } 1569 if (is_mirror) { 1570 /* XXX: Mirror target could be a NBD server of target QEMU in the case 1571 * of non-shared block migration. To allow migration completion, we 1572 * have to allow "inactivate" of the target BB. When that happens, we 1573 * know the job is drained, and the vcpus are stopped, so no write 1574 * operation will be performed. Block layer already has assertions to 1575 * ensure that. */ 1576 blk_set_force_allow_inactivate(s->target); 1577 } 1578 1579 s->replaces = g_strdup(replaces); 1580 s->on_source_error = on_source_error; 1581 s->on_target_error = on_target_error; 1582 s->is_none_mode = is_none_mode; 1583 s->backing_mode = backing_mode; 1584 s->copy_mode = copy_mode; 1585 s->base = base; 1586 s->granularity = granularity; 1587 s->buf_size = ROUND_UP(buf_size, granularity); 1588 s->unmap = unmap; 1589 if (auto_complete) { 1590 s->should_complete = true; 1591 } 1592 1593 s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp); 1594 if (!s->dirty_bitmap) { 1595 goto fail; 1596 } 1597 1598 /* Required permissions are already taken with blk_new() */ 1599 block_job_add_bdrv(&s->common, "target", target, 0, BLK_PERM_ALL, 1600 &error_abort); 1601 1602 /* In commit_active_start() all intermediate nodes disappear, so 1603 * any jobs in them must be blocked */ 1604 if (target_is_backing) { 1605 BlockDriverState *iter; 1606 for (iter = backing_bs(bs); iter != target; iter = backing_bs(iter)) { 1607 /* XXX BLK_PERM_WRITE needs to be allowed so we don't block 1608 * ourselves at s->base (if writes are blocked for a node, they are 1609 * also blocked for its backing file). The other options would be a 1610 * second filter driver above s->base (== target). */ 1611 ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0, 1612 BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE, 1613 errp); 1614 if (ret < 0) { 1615 goto fail; 1616 } 1617 } 1618 } 1619 1620 QTAILQ_INIT(&s->ops_in_flight); 1621 1622 trace_mirror_start(bs, s, opaque); 1623 job_start(&s->common.job); 1624 return; 1625 1626 fail: 1627 if (s) { 1628 /* Make sure this BDS does not go away until we have completed the graph 1629 * changes below */ 1630 bdrv_ref(mirror_top_bs); 1631 1632 g_free(s->replaces); 1633 blk_unref(s->target); 1634 bs_opaque->job = NULL; 1635 job_early_fail(&s->common.job); 1636 } 1637 1638 bdrv_child_try_set_perm(mirror_top_bs->backing, 0, BLK_PERM_ALL, 1639 &error_abort); 1640 bdrv_replace_node(mirror_top_bs, backing_bs(mirror_top_bs), &error_abort); 1641 1642 bdrv_unref(mirror_top_bs); 1643 } 1644 1645 void mirror_start(const char *job_id, BlockDriverState *bs, 1646 BlockDriverState *target, const char *replaces, 1647 int64_t speed, uint32_t granularity, int64_t buf_size, 1648 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode, 1649 BlockdevOnError on_source_error, 1650 BlockdevOnError on_target_error, 1651 bool unmap, const char *filter_node_name, 1652 MirrorCopyMode copy_mode, Error **errp) 1653 { 1654 bool is_none_mode; 1655 BlockDriverState *base; 1656 1657 if (mode == MIRROR_SYNC_MODE_INCREMENTAL) { 1658 error_setg(errp, "Sync mode 'incremental' not supported"); 1659 return; 1660 } 1661 is_none_mode = mode == MIRROR_SYNC_MODE_NONE; 1662 base = mode == MIRROR_SYNC_MODE_TOP ? backing_bs(bs) : NULL; 1663 mirror_start_job(job_id, bs, JOB_DEFAULT, target, replaces, 1664 speed, granularity, buf_size, backing_mode, 1665 on_source_error, on_target_error, unmap, NULL, NULL, 1666 &mirror_job_driver, is_none_mode, base, false, 1667 filter_node_name, true, copy_mode, errp); 1668 } 1669 1670 void commit_active_start(const char *job_id, BlockDriverState *bs, 1671 BlockDriverState *base, int creation_flags, 1672 int64_t speed, BlockdevOnError on_error, 1673 const char *filter_node_name, 1674 BlockCompletionFunc *cb, void *opaque, 1675 bool auto_complete, Error **errp) 1676 { 1677 int orig_base_flags; 1678 Error *local_err = NULL; 1679 1680 orig_base_flags = bdrv_get_flags(base); 1681 1682 if (bdrv_reopen(base, bs->open_flags, errp)) { 1683 return; 1684 } 1685 1686 mirror_start_job(job_id, bs, creation_flags, base, NULL, speed, 0, 0, 1687 MIRROR_LEAVE_BACKING_CHAIN, 1688 on_error, on_error, true, cb, opaque, 1689 &commit_active_job_driver, false, base, auto_complete, 1690 filter_node_name, false, MIRROR_COPY_MODE_BACKGROUND, 1691 &local_err); 1692 if (local_err) { 1693 error_propagate(errp, local_err); 1694 goto error_restore_flags; 1695 } 1696 1697 return; 1698 1699 error_restore_flags: 1700 /* ignore error and errp for bdrv_reopen, because we want to propagate 1701 * the original error */ 1702 bdrv_reopen(base, orig_base_flags, NULL); 1703 return; 1704 } 1705