tests/acceptance/boot_linux: Accept SSH pubkey
[qemu.git] / block / mirror.c
blob26acf4af6fb76ec950aaa9fbb85f3de8a3fe4adf
1 /*
2 * Image mirroring
4 * Copyright Red Hat, Inc. 2012
6 * Authors:
7 * Paolo Bonzini <pbonzini@redhat.com>
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.
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"
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)
31 /* The mirroring buffer is a list of granularity-sized chunks.
32 * Free chunks are organized in a list.
34 typedef struct MirrorBuffer {
35 QSIMPLEQ_ENTRY(MirrorBuffer) next;
36 } MirrorBuffer;
38 typedef struct MirrorOp MirrorOp;
40 typedef struct MirrorBlockJob {
41 BlockJob common;
42 BlockBackend *target;
43 BlockDriverState *mirror_top_bs;
44 BlockDriverState *base;
45 BlockDriverState *base_overlay;
47 /* The name of the graph node to replace */
48 char *replaces;
49 /* The BDS to replace */
50 BlockDriverState *to_replace;
51 /* Used to block operations on the drive-mirror-replace target */
52 Error *replace_blocker;
53 bool is_none_mode;
54 BlockMirrorBackingMode backing_mode;
55 /* Whether the target image requires explicit zero-initialization */
56 bool zero_target;
57 MirrorCopyMode copy_mode;
58 BlockdevOnError on_source_error, on_target_error;
59 bool synced;
60 /* Set when the target is synced (dirty bitmap is clean, nothing
61 * in flight) and the job is running in active mode */
62 bool actively_synced;
63 bool should_complete;
64 int64_t granularity;
65 size_t buf_size;
66 int64_t bdev_length;
67 unsigned long *cow_bitmap;
68 BdrvDirtyBitmap *dirty_bitmap;
69 BdrvDirtyBitmapIter *dbi;
70 uint8_t *buf;
71 QSIMPLEQ_HEAD(, MirrorBuffer) buf_free;
72 int buf_free_count;
74 uint64_t last_pause_ns;
75 unsigned long *in_flight_bitmap;
76 int in_flight;
77 int64_t bytes_in_flight;
78 QTAILQ_HEAD(, MirrorOp) ops_in_flight;
79 int ret;
80 bool unmap;
81 int target_cluster_size;
82 int max_iov;
83 bool initial_zeroing_ongoing;
84 int in_active_write_counter;
85 bool prepared;
86 bool in_drain;
87 } MirrorBlockJob;
89 typedef struct MirrorBDSOpaque {
90 MirrorBlockJob *job;
91 bool stop;
92 } MirrorBDSOpaque;
94 struct MirrorOp {
95 MirrorBlockJob *s;
96 QEMUIOVector qiov;
97 int64_t offset;
98 uint64_t bytes;
100 /* The pointee is set by mirror_co_read(), mirror_co_zero(), and
101 * mirror_co_discard() before yielding for the first time */
102 int64_t *bytes_handled;
104 bool is_pseudo_op;
105 bool is_active_write;
106 bool is_in_flight;
107 CoQueue waiting_requests;
108 Coroutine *co;
110 QTAILQ_ENTRY(MirrorOp) next;
113 typedef enum MirrorMethod {
114 MIRROR_METHOD_COPY,
115 MIRROR_METHOD_ZERO,
116 MIRROR_METHOD_DISCARD,
117 } MirrorMethod;
119 static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read,
120 int error)
122 s->synced = false;
123 s->actively_synced = false;
124 if (read) {
125 return block_job_error_action(&s->common, s->on_source_error,
126 true, error);
127 } else {
128 return block_job_error_action(&s->common, s->on_target_error,
129 false, error);
133 static void coroutine_fn mirror_wait_on_conflicts(MirrorOp *self,
134 MirrorBlockJob *s,
135 uint64_t offset,
136 uint64_t bytes)
138 uint64_t self_start_chunk = offset / s->granularity;
139 uint64_t self_end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity);
140 uint64_t self_nb_chunks = self_end_chunk - self_start_chunk;
142 while (find_next_bit(s->in_flight_bitmap, self_end_chunk,
143 self_start_chunk) < self_end_chunk &&
144 s->ret >= 0)
146 MirrorOp *op;
148 QTAILQ_FOREACH(op, &s->ops_in_flight, next) {
149 uint64_t op_start_chunk = op->offset / s->granularity;
150 uint64_t op_nb_chunks = DIV_ROUND_UP(op->offset + op->bytes,
151 s->granularity) -
152 op_start_chunk;
154 if (op == self) {
155 continue;
158 if (ranges_overlap(self_start_chunk, self_nb_chunks,
159 op_start_chunk, op_nb_chunks))
161 qemu_co_queue_wait(&op->waiting_requests, NULL);
162 break;
168 static void coroutine_fn mirror_iteration_done(MirrorOp *op, int ret)
170 MirrorBlockJob *s = op->s;
171 struct iovec *iov;
172 int64_t chunk_num;
173 int i, nb_chunks;
175 trace_mirror_iteration_done(s, op->offset, op->bytes, ret);
177 s->in_flight--;
178 s->bytes_in_flight -= op->bytes;
179 iov = op->qiov.iov;
180 for (i = 0; i < op->qiov.niov; i++) {
181 MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base;
182 QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next);
183 s->buf_free_count++;
186 chunk_num = op->offset / s->granularity;
187 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity);
189 bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks);
190 QTAILQ_REMOVE(&s->ops_in_flight, op, next);
191 if (ret >= 0) {
192 if (s->cow_bitmap) {
193 bitmap_set(s->cow_bitmap, chunk_num, nb_chunks);
195 if (!s->initial_zeroing_ongoing) {
196 job_progress_update(&s->common.job, op->bytes);
199 qemu_iovec_destroy(&op->qiov);
201 qemu_co_queue_restart_all(&op->waiting_requests);
202 g_free(op);
205 static void coroutine_fn mirror_write_complete(MirrorOp *op, int ret)
207 MirrorBlockJob *s = op->s;
209 if (ret < 0) {
210 BlockErrorAction action;
212 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes);
213 action = mirror_error_action(s, false, -ret);
214 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) {
215 s->ret = ret;
219 mirror_iteration_done(op, ret);
222 static void coroutine_fn mirror_read_complete(MirrorOp *op, int ret)
224 MirrorBlockJob *s = op->s;
226 if (ret < 0) {
227 BlockErrorAction action;
229 bdrv_set_dirty_bitmap(s->dirty_bitmap, op->offset, op->bytes);
230 action = mirror_error_action(s, true, -ret);
231 if (action == BLOCK_ERROR_ACTION_REPORT && s->ret >= 0) {
232 s->ret = ret;
235 mirror_iteration_done(op, ret);
236 return;
239 ret = blk_co_pwritev(s->target, op->offset, op->qiov.size, &op->qiov, 0);
240 mirror_write_complete(op, ret);
243 /* Clip bytes relative to offset to not exceed end-of-file */
244 static inline int64_t mirror_clip_bytes(MirrorBlockJob *s,
245 int64_t offset,
246 int64_t bytes)
248 return MIN(bytes, s->bdev_length - offset);
251 /* Round offset and/or bytes to target cluster if COW is needed, and
252 * return the offset of the adjusted tail against original. */
253 static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset,
254 uint64_t *bytes)
256 bool need_cow;
257 int ret = 0;
258 int64_t align_offset = *offset;
259 int64_t align_bytes = *bytes;
260 int max_bytes = s->granularity * s->max_iov;
262 need_cow = !test_bit(*offset / s->granularity, s->cow_bitmap);
263 need_cow |= !test_bit((*offset + *bytes - 1) / s->granularity,
264 s->cow_bitmap);
265 if (need_cow) {
266 bdrv_round_to_clusters(blk_bs(s->target), *offset, *bytes,
267 &align_offset, &align_bytes);
270 if (align_bytes > max_bytes) {
271 align_bytes = max_bytes;
272 if (need_cow) {
273 align_bytes = QEMU_ALIGN_DOWN(align_bytes, s->target_cluster_size);
276 /* Clipping may result in align_bytes unaligned to chunk boundary, but
277 * that doesn't matter because it's already the end of source image. */
278 align_bytes = mirror_clip_bytes(s, align_offset, align_bytes);
280 ret = align_offset + align_bytes - (*offset + *bytes);
281 *offset = align_offset;
282 *bytes = align_bytes;
283 assert(ret >= 0);
284 return ret;
287 static inline void coroutine_fn
288 mirror_wait_for_any_operation(MirrorBlockJob *s, bool active)
290 MirrorOp *op;
292 QTAILQ_FOREACH(op, &s->ops_in_flight, next) {
293 /* Do not wait on pseudo ops, because it may in turn wait on
294 * some other operation to start, which may in fact be the
295 * caller of this function. Since there is only one pseudo op
296 * at any given time, we will always find some real operation
297 * to wait on. */
298 if (!op->is_pseudo_op && op->is_in_flight &&
299 op->is_active_write == active)
301 qemu_co_queue_wait(&op->waiting_requests, NULL);
302 return;
305 abort();
308 static inline void coroutine_fn
309 mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s)
311 /* Only non-active operations use up in-flight slots */
312 mirror_wait_for_any_operation(s, false);
315 /* Perform a mirror copy operation.
317 * *op->bytes_handled is set to the number of bytes copied after and
318 * including offset, excluding any bytes copied prior to offset due
319 * to alignment. This will be op->bytes if no alignment is necessary,
320 * or (new_end - op->offset) if the tail is rounded up or down due to
321 * alignment or buffer limit.
323 static void coroutine_fn mirror_co_read(void *opaque)
325 MirrorOp *op = opaque;
326 MirrorBlockJob *s = op->s;
327 int nb_chunks;
328 uint64_t ret;
329 uint64_t max_bytes;
331 max_bytes = s->granularity * s->max_iov;
333 /* We can only handle as much as buf_size at a time. */
334 op->bytes = MIN(s->buf_size, MIN(max_bytes, op->bytes));
335 assert(op->bytes);
336 assert(op->bytes < BDRV_REQUEST_MAX_BYTES);
337 *op->bytes_handled = op->bytes;
339 if (s->cow_bitmap) {
340 *op->bytes_handled += mirror_cow_align(s, &op->offset, &op->bytes);
342 /* Cannot exceed BDRV_REQUEST_MAX_BYTES + INT_MAX */
343 assert(*op->bytes_handled <= UINT_MAX);
344 assert(op->bytes <= s->buf_size);
345 /* The offset is granularity-aligned because:
346 * 1) Caller passes in aligned values;
347 * 2) mirror_cow_align is used only when target cluster is larger. */
348 assert(QEMU_IS_ALIGNED(op->offset, s->granularity));
349 /* The range is sector-aligned, since bdrv_getlength() rounds up. */
350 assert(QEMU_IS_ALIGNED(op->bytes, BDRV_SECTOR_SIZE));
351 nb_chunks = DIV_ROUND_UP(op->bytes, s->granularity);
353 while (s->buf_free_count < nb_chunks) {
354 trace_mirror_yield_in_flight(s, op->offset, s->in_flight);
355 mirror_wait_for_free_in_flight_slot(s);
358 /* Now make a QEMUIOVector taking enough granularity-sized chunks
359 * from s->buf_free.
361 qemu_iovec_init(&op->qiov, nb_chunks);
362 while (nb_chunks-- > 0) {
363 MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free);
364 size_t remaining = op->bytes - op->qiov.size;
366 QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next);
367 s->buf_free_count--;
368 qemu_iovec_add(&op->qiov, buf, MIN(s->granularity, remaining));
371 /* Copy the dirty cluster. */
372 s->in_flight++;
373 s->bytes_in_flight += op->bytes;
374 op->is_in_flight = true;
375 trace_mirror_one_iteration(s, op->offset, op->bytes);
377 ret = bdrv_co_preadv(s->mirror_top_bs->backing, op->offset, op->bytes,
378 &op->qiov, 0);
379 mirror_read_complete(op, ret);
382 static void coroutine_fn mirror_co_zero(void *opaque)
384 MirrorOp *op = opaque;
385 int ret;
387 op->s->in_flight++;
388 op->s->bytes_in_flight += op->bytes;
389 *op->bytes_handled = op->bytes;
390 op->is_in_flight = true;
392 ret = blk_co_pwrite_zeroes(op->s->target, op->offset, op->bytes,
393 op->s->unmap ? BDRV_REQ_MAY_UNMAP : 0);
394 mirror_write_complete(op, ret);
397 static void coroutine_fn mirror_co_discard(void *opaque)
399 MirrorOp *op = opaque;
400 int ret;
402 op->s->in_flight++;
403 op->s->bytes_in_flight += op->bytes;
404 *op->bytes_handled = op->bytes;
405 op->is_in_flight = true;
407 ret = blk_co_pdiscard(op->s->target, op->offset, op->bytes);
408 mirror_write_complete(op, ret);
411 static unsigned mirror_perform(MirrorBlockJob *s, int64_t offset,
412 unsigned bytes, MirrorMethod mirror_method)
414 MirrorOp *op;
415 Coroutine *co;
416 int64_t bytes_handled = -1;
418 op = g_new(MirrorOp, 1);
419 *op = (MirrorOp){
420 .s = s,
421 .offset = offset,
422 .bytes = bytes,
423 .bytes_handled = &bytes_handled,
425 qemu_co_queue_init(&op->waiting_requests);
427 switch (mirror_method) {
428 case MIRROR_METHOD_COPY:
429 co = qemu_coroutine_create(mirror_co_read, op);
430 break;
431 case MIRROR_METHOD_ZERO:
432 co = qemu_coroutine_create(mirror_co_zero, op);
433 break;
434 case MIRROR_METHOD_DISCARD:
435 co = qemu_coroutine_create(mirror_co_discard, op);
436 break;
437 default:
438 abort();
440 op->co = co;
442 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next);
443 qemu_coroutine_enter(co);
444 /* At this point, ownership of op has been moved to the coroutine
445 * and the object may already be freed */
447 /* Assert that this value has been set */
448 assert(bytes_handled >= 0);
450 /* Same assertion as in mirror_co_read() (and for mirror_co_read()
451 * and mirror_co_discard(), bytes_handled == op->bytes, which
452 * is the @bytes parameter given to this function) */
453 assert(bytes_handled <= UINT_MAX);
454 return bytes_handled;
457 static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
459 BlockDriverState *source = s->mirror_top_bs->backing->bs;
460 MirrorOp *pseudo_op;
461 int64_t offset;
462 uint64_t delay_ns = 0, ret = 0;
463 /* At least the first dirty chunk is mirrored in one iteration. */
464 int nb_chunks = 1;
465 bool write_zeroes_ok = bdrv_can_write_zeroes_with_unmap(blk_bs(s->target));
466 int max_io_bytes = MAX(s->buf_size / MAX_IN_FLIGHT, MAX_IO_BYTES);
468 bdrv_dirty_bitmap_lock(s->dirty_bitmap);
469 offset = bdrv_dirty_iter_next(s->dbi);
470 if (offset < 0) {
471 bdrv_set_dirty_iter(s->dbi, 0);
472 offset = bdrv_dirty_iter_next(s->dbi);
473 trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap));
474 assert(offset >= 0);
476 bdrv_dirty_bitmap_unlock(s->dirty_bitmap);
478 mirror_wait_on_conflicts(NULL, s, offset, 1);
480 job_pause_point(&s->common.job);
482 /* Find the number of consective dirty chunks following the first dirty
483 * one, and wait for in flight requests in them. */
484 bdrv_dirty_bitmap_lock(s->dirty_bitmap);
485 while (nb_chunks * s->granularity < s->buf_size) {
486 int64_t next_dirty;
487 int64_t next_offset = offset + nb_chunks * s->granularity;
488 int64_t next_chunk = next_offset / s->granularity;
489 if (next_offset >= s->bdev_length ||
490 !bdrv_dirty_bitmap_get_locked(s->dirty_bitmap, next_offset)) {
491 break;
493 if (test_bit(next_chunk, s->in_flight_bitmap)) {
494 break;
497 next_dirty = bdrv_dirty_iter_next(s->dbi);
498 if (next_dirty > next_offset || next_dirty < 0) {
499 /* The bitmap iterator's cache is stale, refresh it */
500 bdrv_set_dirty_iter(s->dbi, next_offset);
501 next_dirty = bdrv_dirty_iter_next(s->dbi);
503 assert(next_dirty == next_offset);
504 nb_chunks++;
507 /* Clear dirty bits before querying the block status, because
508 * calling bdrv_block_status_above could yield - if some blocks are
509 * marked dirty in this window, we need to know.
511 bdrv_reset_dirty_bitmap_locked(s->dirty_bitmap, offset,
512 nb_chunks * s->granularity);
513 bdrv_dirty_bitmap_unlock(s->dirty_bitmap);
515 /* Before claiming an area in the in-flight bitmap, we have to
516 * create a MirrorOp for it so that conflicting requests can wait
517 * for it. mirror_perform() will create the real MirrorOps later,
518 * for now we just create a pseudo operation that will wake up all
519 * conflicting requests once all real operations have been
520 * launched. */
521 pseudo_op = g_new(MirrorOp, 1);
522 *pseudo_op = (MirrorOp){
523 .offset = offset,
524 .bytes = nb_chunks * s->granularity,
525 .is_pseudo_op = true,
527 qemu_co_queue_init(&pseudo_op->waiting_requests);
528 QTAILQ_INSERT_TAIL(&s->ops_in_flight, pseudo_op, next);
530 bitmap_set(s->in_flight_bitmap, offset / s->granularity, nb_chunks);
531 while (nb_chunks > 0 && offset < s->bdev_length) {
532 int ret;
533 int64_t io_bytes;
534 int64_t io_bytes_acct;
535 MirrorMethod mirror_method = MIRROR_METHOD_COPY;
537 assert(!(offset % s->granularity));
538 ret = bdrv_block_status_above(source, NULL, offset,
539 nb_chunks * s->granularity,
540 &io_bytes, NULL, NULL);
541 if (ret < 0) {
542 io_bytes = MIN(nb_chunks * s->granularity, max_io_bytes);
543 } else if (ret & BDRV_BLOCK_DATA) {
544 io_bytes = MIN(io_bytes, max_io_bytes);
547 io_bytes -= io_bytes % s->granularity;
548 if (io_bytes < s->granularity) {
549 io_bytes = s->granularity;
550 } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) {
551 int64_t target_offset;
552 int64_t target_bytes;
553 bdrv_round_to_clusters(blk_bs(s->target), offset, io_bytes,
554 &target_offset, &target_bytes);
555 if (target_offset == offset &&
556 target_bytes == io_bytes) {
557 mirror_method = ret & BDRV_BLOCK_ZERO ?
558 MIRROR_METHOD_ZERO :
559 MIRROR_METHOD_DISCARD;
563 while (s->in_flight >= MAX_IN_FLIGHT) {
564 trace_mirror_yield_in_flight(s, offset, s->in_flight);
565 mirror_wait_for_free_in_flight_slot(s);
568 if (s->ret < 0) {
569 ret = 0;
570 goto fail;
573 io_bytes = mirror_clip_bytes(s, offset, io_bytes);
574 io_bytes = mirror_perform(s, offset, io_bytes, mirror_method);
575 if (mirror_method != MIRROR_METHOD_COPY && write_zeroes_ok) {
576 io_bytes_acct = 0;
577 } else {
578 io_bytes_acct = io_bytes;
580 assert(io_bytes);
581 offset += io_bytes;
582 nb_chunks -= DIV_ROUND_UP(io_bytes, s->granularity);
583 delay_ns = block_job_ratelimit_get_delay(&s->common, io_bytes_acct);
586 ret = delay_ns;
587 fail:
588 QTAILQ_REMOVE(&s->ops_in_flight, pseudo_op, next);
589 qemu_co_queue_restart_all(&pseudo_op->waiting_requests);
590 g_free(pseudo_op);
592 return ret;
595 static void mirror_free_init(MirrorBlockJob *s)
597 int granularity = s->granularity;
598 size_t buf_size = s->buf_size;
599 uint8_t *buf = s->buf;
601 assert(s->buf_free_count == 0);
602 QSIMPLEQ_INIT(&s->buf_free);
603 while (buf_size != 0) {
604 MirrorBuffer *cur = (MirrorBuffer *)buf;
605 QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next);
606 s->buf_free_count++;
607 buf_size -= granularity;
608 buf += granularity;
612 /* This is also used for the .pause callback. There is no matching
613 * mirror_resume() because mirror_run() will begin iterating again
614 * when the job is resumed.
616 static void coroutine_fn mirror_wait_for_all_io(MirrorBlockJob *s)
618 while (s->in_flight > 0) {
619 mirror_wait_for_free_in_flight_slot(s);
624 * mirror_exit_common: handle both abort() and prepare() cases.
625 * for .prepare, returns 0 on success and -errno on failure.
626 * for .abort cases, denoted by abort = true, MUST return 0.
628 static int mirror_exit_common(Job *job)
630 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job);
631 BlockJob *bjob = &s->common;
632 MirrorBDSOpaque *bs_opaque;
633 AioContext *replace_aio_context = NULL;
634 BlockDriverState *src;
635 BlockDriverState *target_bs;
636 BlockDriverState *mirror_top_bs;
637 Error *local_err = NULL;
638 bool abort = job->ret < 0;
639 int ret = 0;
641 if (s->prepared) {
642 return 0;
644 s->prepared = true;
646 mirror_top_bs = s->mirror_top_bs;
647 bs_opaque = mirror_top_bs->opaque;
648 src = mirror_top_bs->backing->bs;
649 target_bs = blk_bs(s->target);
651 if (bdrv_chain_contains(src, target_bs)) {
652 bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs);
655 bdrv_release_dirty_bitmap(s->dirty_bitmap);
657 /* Make sure that the source BDS doesn't go away during bdrv_replace_node,
658 * before we can call bdrv_drained_end */
659 bdrv_ref(src);
660 bdrv_ref(mirror_top_bs);
661 bdrv_ref(target_bs);
664 * Remove target parent that still uses BLK_PERM_WRITE/RESIZE before
665 * inserting target_bs at s->to_replace, where we might not be able to get
666 * these permissions.
668 blk_unref(s->target);
669 s->target = NULL;
671 /* We don't access the source any more. Dropping any WRITE/RESIZE is
672 * required before it could become a backing file of target_bs. Not having
673 * these permissions any more means that we can't allow any new requests on
674 * mirror_top_bs from now on, so keep it drained. */
675 bdrv_drained_begin(mirror_top_bs);
676 bs_opaque->stop = true;
677 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing,
678 &error_abort);
679 if (!abort && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) {
680 BlockDriverState *backing = s->is_none_mode ? src : s->base;
681 BlockDriverState *unfiltered_target = bdrv_skip_filters(target_bs);
683 if (bdrv_cow_bs(unfiltered_target) != backing) {
684 bdrv_set_backing_hd(unfiltered_target, backing, &local_err);
685 if (local_err) {
686 error_report_err(local_err);
687 local_err = NULL;
688 ret = -EPERM;
693 if (s->to_replace) {
694 replace_aio_context = bdrv_get_aio_context(s->to_replace);
695 aio_context_acquire(replace_aio_context);
698 if (s->should_complete && !abort) {
699 BlockDriverState *to_replace = s->to_replace ?: src;
700 bool ro = bdrv_is_read_only(to_replace);
702 if (ro != bdrv_is_read_only(target_bs)) {
703 bdrv_reopen_set_read_only(target_bs, ro, NULL);
706 /* The mirror job has no requests in flight any more, but we need to
707 * drain potential other users of the BDS before changing the graph. */
708 assert(s->in_drain);
709 bdrv_drained_begin(target_bs);
711 * Cannot use check_to_replace_node() here, because that would
712 * check for an op blocker on @to_replace, and we have our own
713 * there.
715 if (bdrv_recurse_can_replace(src, to_replace)) {
716 bdrv_replace_node(to_replace, target_bs, &local_err);
717 } else {
718 error_setg(&local_err, "Can no longer replace '%s' by '%s', "
719 "because it can no longer be guaranteed that doing so "
720 "would not lead to an abrupt change of visible data",
721 to_replace->node_name, target_bs->node_name);
723 bdrv_drained_end(target_bs);
724 if (local_err) {
725 error_report_err(local_err);
726 ret = -EPERM;
729 if (s->to_replace) {
730 bdrv_op_unblock_all(s->to_replace, s->replace_blocker);
731 error_free(s->replace_blocker);
732 bdrv_unref(s->to_replace);
734 if (replace_aio_context) {
735 aio_context_release(replace_aio_context);
737 g_free(s->replaces);
738 bdrv_unref(target_bs);
741 * Remove the mirror filter driver from the graph. Before this, get rid of
742 * the blockers on the intermediate nodes so that the resulting state is
743 * valid.
745 block_job_remove_all_bdrv(bjob);
746 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort);
748 /* We just changed the BDS the job BB refers to (with either or both of the
749 * bdrv_replace_node() calls), so switch the BB back so the cleanup does
750 * the right thing. We don't need any permissions any more now. */
751 blk_remove_bs(bjob->blk);
752 blk_set_perm(bjob->blk, 0, BLK_PERM_ALL, &error_abort);
753 blk_insert_bs(bjob->blk, mirror_top_bs, &error_abort);
755 bs_opaque->job = NULL;
757 bdrv_drained_end(src);
758 bdrv_drained_end(mirror_top_bs);
759 s->in_drain = false;
760 bdrv_unref(mirror_top_bs);
761 bdrv_unref(src);
763 return ret;
766 static int mirror_prepare(Job *job)
768 return mirror_exit_common(job);
771 static void mirror_abort(Job *job)
773 int ret = mirror_exit_common(job);
774 assert(ret == 0);
777 static void coroutine_fn mirror_throttle(MirrorBlockJob *s)
779 int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
781 if (now - s->last_pause_ns > BLOCK_JOB_SLICE_TIME) {
782 s->last_pause_ns = now;
783 job_sleep_ns(&s->common.job, 0);
784 } else {
785 job_pause_point(&s->common.job);
789 static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s)
791 int64_t offset;
792 BlockDriverState *bs = s->mirror_top_bs->backing->bs;
793 BlockDriverState *target_bs = blk_bs(s->target);
794 int ret;
795 int64_t count;
797 if (s->zero_target) {
798 if (!bdrv_can_write_zeroes_with_unmap(target_bs)) {
799 bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, s->bdev_length);
800 return 0;
803 s->initial_zeroing_ongoing = true;
804 for (offset = 0; offset < s->bdev_length; ) {
805 int bytes = MIN(s->bdev_length - offset,
806 QEMU_ALIGN_DOWN(INT_MAX, s->granularity));
808 mirror_throttle(s);
810 if (job_is_cancelled(&s->common.job)) {
811 s->initial_zeroing_ongoing = false;
812 return 0;
815 if (s->in_flight >= MAX_IN_FLIGHT) {
816 trace_mirror_yield(s, UINT64_MAX, s->buf_free_count,
817 s->in_flight);
818 mirror_wait_for_free_in_flight_slot(s);
819 continue;
822 mirror_perform(s, offset, bytes, MIRROR_METHOD_ZERO);
823 offset += bytes;
826 mirror_wait_for_all_io(s);
827 s->initial_zeroing_ongoing = false;
830 /* First part, loop on the sectors and initialize the dirty bitmap. */
831 for (offset = 0; offset < s->bdev_length; ) {
832 /* Just to make sure we are not exceeding int limit. */
833 int bytes = MIN(s->bdev_length - offset,
834 QEMU_ALIGN_DOWN(INT_MAX, s->granularity));
836 mirror_throttle(s);
838 if (job_is_cancelled(&s->common.job)) {
839 return 0;
842 ret = bdrv_is_allocated_above(bs, s->base_overlay, true, offset, bytes,
843 &count);
844 if (ret < 0) {
845 return ret;
848 assert(count);
849 if (ret == 1) {
850 bdrv_set_dirty_bitmap(s->dirty_bitmap, offset, count);
852 offset += count;
854 return 0;
857 /* Called when going out of the streaming phase to flush the bulk of the
858 * data to the medium, or just before completing.
860 static int mirror_flush(MirrorBlockJob *s)
862 int ret = blk_flush(s->target);
863 if (ret < 0) {
864 if (mirror_error_action(s, false, -ret) == BLOCK_ERROR_ACTION_REPORT) {
865 s->ret = ret;
868 return ret;
871 static int coroutine_fn mirror_run(Job *job, Error **errp)
873 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job);
874 BlockDriverState *bs = s->mirror_top_bs->backing->bs;
875 BlockDriverState *target_bs = blk_bs(s->target);
876 bool need_drain = true;
877 int64_t length;
878 int64_t target_length;
879 BlockDriverInfo bdi;
880 char backing_filename[2]; /* we only need 2 characters because we are only
881 checking for a NULL string */
882 int ret = 0;
884 if (job_is_cancelled(&s->common.job)) {
885 goto immediate_exit;
888 s->bdev_length = bdrv_getlength(bs);
889 if (s->bdev_length < 0) {
890 ret = s->bdev_length;
891 goto immediate_exit;
894 target_length = blk_getlength(s->target);
895 if (target_length < 0) {
896 ret = target_length;
897 goto immediate_exit;
900 /* Active commit must resize the base image if its size differs from the
901 * active layer. */
902 if (s->base == blk_bs(s->target)) {
903 if (s->bdev_length > target_length) {
904 ret = blk_truncate(s->target, s->bdev_length, false,
905 PREALLOC_MODE_OFF, 0, NULL);
906 if (ret < 0) {
907 goto immediate_exit;
910 } else if (s->bdev_length != target_length) {
911 error_setg(errp, "Source and target image have different sizes");
912 ret = -EINVAL;
913 goto immediate_exit;
916 if (s->bdev_length == 0) {
917 /* Transition to the READY state and wait for complete. */
918 job_transition_to_ready(&s->common.job);
919 s->synced = true;
920 s->actively_synced = true;
921 while (!job_is_cancelled(&s->common.job) && !s->should_complete) {
922 job_yield(&s->common.job);
924 s->common.job.cancelled = false;
925 goto immediate_exit;
928 length = DIV_ROUND_UP(s->bdev_length, s->granularity);
929 s->in_flight_bitmap = bitmap_new(length);
931 /* If we have no backing file yet in the destination, we cannot let
932 * the destination do COW. Instead, we copy sectors around the
933 * dirty data if needed. We need a bitmap to do that.
935 bdrv_get_backing_filename(target_bs, backing_filename,
936 sizeof(backing_filename));
937 if (!bdrv_get_info(target_bs, &bdi) && bdi.cluster_size) {
938 s->target_cluster_size = bdi.cluster_size;
939 } else {
940 s->target_cluster_size = BDRV_SECTOR_SIZE;
942 if (backing_filename[0] && !bdrv_backing_chain_next(target_bs) &&
943 s->granularity < s->target_cluster_size) {
944 s->buf_size = MAX(s->buf_size, s->target_cluster_size);
945 s->cow_bitmap = bitmap_new(length);
947 s->max_iov = MIN(bs->bl.max_iov, target_bs->bl.max_iov);
949 s->buf = qemu_try_blockalign(bs, s->buf_size);
950 if (s->buf == NULL) {
951 ret = -ENOMEM;
952 goto immediate_exit;
955 mirror_free_init(s);
957 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
958 if (!s->is_none_mode) {
959 ret = mirror_dirty_init(s);
960 if (ret < 0 || job_is_cancelled(&s->common.job)) {
961 goto immediate_exit;
965 assert(!s->dbi);
966 s->dbi = bdrv_dirty_iter_new(s->dirty_bitmap);
967 for (;;) {
968 uint64_t delay_ns = 0;
969 int64_t cnt, delta;
970 bool should_complete;
972 /* Do not start passive operations while there are active
973 * writes in progress */
974 while (s->in_active_write_counter) {
975 mirror_wait_for_any_operation(s, true);
978 if (s->ret < 0) {
979 ret = s->ret;
980 goto immediate_exit;
983 job_pause_point(&s->common.job);
985 cnt = bdrv_get_dirty_count(s->dirty_bitmap);
986 /* cnt is the number of dirty bytes remaining and s->bytes_in_flight is
987 * the number of bytes currently being processed; together those are
988 * the current remaining operation length */
989 job_progress_set_remaining(&s->common.job, s->bytes_in_flight + cnt);
991 /* Note that even when no rate limit is applied we need to yield
992 * periodically with no pending I/O so that bdrv_drain_all() returns.
993 * We do so every BLKOCK_JOB_SLICE_TIME nanoseconds, or when there is
994 * an error, or when the source is clean, whichever comes first. */
995 delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns;
996 if (delta < BLOCK_JOB_SLICE_TIME &&
997 s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
998 if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 ||
999 (cnt == 0 && s->in_flight > 0)) {
1000 trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight);
1001 mirror_wait_for_free_in_flight_slot(s);
1002 continue;
1003 } else if (cnt != 0) {
1004 delay_ns = mirror_iteration(s);
1008 should_complete = false;
1009 if (s->in_flight == 0 && cnt == 0) {
1010 trace_mirror_before_flush(s);
1011 if (!s->synced) {
1012 if (mirror_flush(s) < 0) {
1013 /* Go check s->ret. */
1014 continue;
1016 /* We're out of the streaming phase. From now on, if the job
1017 * is cancelled we will actually complete all pending I/O and
1018 * report completion. This way, block-job-cancel will leave
1019 * the target in a consistent state.
1021 job_transition_to_ready(&s->common.job);
1022 s->synced = true;
1023 if (s->copy_mode != MIRROR_COPY_MODE_BACKGROUND) {
1024 s->actively_synced = true;
1028 should_complete = s->should_complete ||
1029 job_is_cancelled(&s->common.job);
1030 cnt = bdrv_get_dirty_count(s->dirty_bitmap);
1033 if (cnt == 0 && should_complete) {
1034 /* The dirty bitmap is not updated while operations are pending.
1035 * If we're about to exit, wait for pending operations before
1036 * calling bdrv_get_dirty_count(bs), or we may exit while the
1037 * source has dirty data to copy!
1039 * Note that I/O can be submitted by the guest while
1040 * mirror_populate runs, so pause it now. Before deciding
1041 * whether to switch to target check one last time if I/O has
1042 * come in the meanwhile, and if not flush the data to disk.
1044 trace_mirror_before_drain(s, cnt);
1046 s->in_drain = true;
1047 bdrv_drained_begin(bs);
1048 cnt = bdrv_get_dirty_count(s->dirty_bitmap);
1049 if (cnt > 0 || mirror_flush(s) < 0) {
1050 bdrv_drained_end(bs);
1051 s->in_drain = false;
1052 continue;
1055 /* The two disks are in sync. Exit and report successful
1056 * completion.
1058 assert(QLIST_EMPTY(&bs->tracked_requests));
1059 s->common.job.cancelled = false;
1060 need_drain = false;
1061 break;
1064 ret = 0;
1066 if (s->synced && !should_complete) {
1067 delay_ns = (s->in_flight == 0 &&
1068 cnt == 0 ? BLOCK_JOB_SLICE_TIME : 0);
1070 trace_mirror_before_sleep(s, cnt, s->synced, delay_ns);
1071 job_sleep_ns(&s->common.job, delay_ns);
1072 if (job_is_cancelled(&s->common.job) &&
1073 (!s->synced || s->common.job.force_cancel))
1075 break;
1077 s->last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
1080 immediate_exit:
1081 if (s->in_flight > 0) {
1082 /* We get here only if something went wrong. Either the job failed,
1083 * or it was cancelled prematurely so that we do not guarantee that
1084 * the target is a copy of the source.
1086 assert(ret < 0 || ((s->common.job.force_cancel || !s->synced) &&
1087 job_is_cancelled(&s->common.job)));
1088 assert(need_drain);
1089 mirror_wait_for_all_io(s);
1092 assert(s->in_flight == 0);
1093 qemu_vfree(s->buf);
1094 g_free(s->cow_bitmap);
1095 g_free(s->in_flight_bitmap);
1096 bdrv_dirty_iter_free(s->dbi);
1098 if (need_drain) {
1099 s->in_drain = true;
1100 bdrv_drained_begin(bs);
1103 return ret;
1106 static void mirror_complete(Job *job, Error **errp)
1108 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job);
1109 BlockDriverState *target;
1111 target = blk_bs(s->target);
1113 if (!s->synced) {
1114 error_setg(errp, "The active block job '%s' cannot be completed",
1115 job->id);
1116 return;
1119 if (s->backing_mode == MIRROR_OPEN_BACKING_CHAIN) {
1120 int ret;
1122 assert(!bdrv_backing_chain_next(target));
1123 ret = bdrv_open_backing_file(bdrv_skip_filters(target), NULL,
1124 "backing", errp);
1125 if (ret < 0) {
1126 return;
1130 /* block all operations on to_replace bs */
1131 if (s->replaces) {
1132 AioContext *replace_aio_context;
1134 s->to_replace = bdrv_find_node(s->replaces);
1135 if (!s->to_replace) {
1136 error_setg(errp, "Node name '%s' not found", s->replaces);
1137 return;
1140 replace_aio_context = bdrv_get_aio_context(s->to_replace);
1141 aio_context_acquire(replace_aio_context);
1143 /* TODO Translate this into permission system. Current definition of
1144 * GRAPH_MOD would require to request it for the parents; they might
1145 * not even be BlockDriverStates, however, so a BdrvChild can't address
1146 * them. May need redefinition of GRAPH_MOD. */
1147 error_setg(&s->replace_blocker,
1148 "block device is in use by block-job-complete");
1149 bdrv_op_block_all(s->to_replace, s->replace_blocker);
1150 bdrv_ref(s->to_replace);
1152 aio_context_release(replace_aio_context);
1155 s->should_complete = true;
1156 job_enter(job);
1159 static void coroutine_fn mirror_pause(Job *job)
1161 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job);
1163 mirror_wait_for_all_io(s);
1166 static bool mirror_drained_poll(BlockJob *job)
1168 MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
1170 /* If the job isn't paused nor cancelled, we can't be sure that it won't
1171 * issue more requests. We make an exception if we've reached this point
1172 * from one of our own drain sections, to avoid a deadlock waiting for
1173 * ourselves.
1175 if (!s->common.job.paused && !s->common.job.cancelled && !s->in_drain) {
1176 return true;
1179 return !!s->in_flight;
1182 static const BlockJobDriver mirror_job_driver = {
1183 .job_driver = {
1184 .instance_size = sizeof(MirrorBlockJob),
1185 .job_type = JOB_TYPE_MIRROR,
1186 .free = block_job_free,
1187 .user_resume = block_job_user_resume,
1188 .run = mirror_run,
1189 .prepare = mirror_prepare,
1190 .abort = mirror_abort,
1191 .pause = mirror_pause,
1192 .complete = mirror_complete,
1194 .drained_poll = mirror_drained_poll,
1197 static const BlockJobDriver commit_active_job_driver = {
1198 .job_driver = {
1199 .instance_size = sizeof(MirrorBlockJob),
1200 .job_type = JOB_TYPE_COMMIT,
1201 .free = block_job_free,
1202 .user_resume = block_job_user_resume,
1203 .run = mirror_run,
1204 .prepare = mirror_prepare,
1205 .abort = mirror_abort,
1206 .pause = mirror_pause,
1207 .complete = mirror_complete,
1209 .drained_poll = mirror_drained_poll,
1212 static void coroutine_fn
1213 do_sync_target_write(MirrorBlockJob *job, MirrorMethod method,
1214 uint64_t offset, uint64_t bytes,
1215 QEMUIOVector *qiov, int flags)
1217 int ret;
1218 size_t qiov_offset = 0;
1219 int64_t bitmap_offset, bitmap_end;
1221 if (!QEMU_IS_ALIGNED(offset, job->granularity) &&
1222 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset))
1225 * Dirty unaligned padding: ignore it.
1227 * Reasoning:
1228 * 1. If we copy it, we can't reset corresponding bit in
1229 * dirty_bitmap as there may be some "dirty" bytes still not
1230 * copied.
1231 * 2. It's already dirty, so skipping it we don't diverge mirror
1232 * progress.
1234 * Note, that because of this, guest write may have no contribution
1235 * into mirror converge, but that's not bad, as we have background
1236 * process of mirroring. If under some bad circumstances (high guest
1237 * IO load) background process starve, we will not converge anyway,
1238 * even if each write will contribute, as guest is not guaranteed to
1239 * rewrite the whole disk.
1241 qiov_offset = QEMU_ALIGN_UP(offset, job->granularity) - offset;
1242 if (bytes <= qiov_offset) {
1243 /* nothing to do after shrink */
1244 return;
1246 offset += qiov_offset;
1247 bytes -= qiov_offset;
1250 if (!QEMU_IS_ALIGNED(offset + bytes, job->granularity) &&
1251 bdrv_dirty_bitmap_get(job->dirty_bitmap, offset + bytes - 1))
1253 uint64_t tail = (offset + bytes) % job->granularity;
1255 if (bytes <= tail) {
1256 /* nothing to do after shrink */
1257 return;
1259 bytes -= tail;
1263 * Tails are either clean or shrunk, so for bitmap resetting
1264 * we safely align the range down.
1266 bitmap_offset = QEMU_ALIGN_UP(offset, job->granularity);
1267 bitmap_end = QEMU_ALIGN_DOWN(offset + bytes, job->granularity);
1268 if (bitmap_offset < bitmap_end) {
1269 bdrv_reset_dirty_bitmap(job->dirty_bitmap, bitmap_offset,
1270 bitmap_end - bitmap_offset);
1273 job_progress_increase_remaining(&job->common.job, bytes);
1275 switch (method) {
1276 case MIRROR_METHOD_COPY:
1277 ret = blk_co_pwritev_part(job->target, offset, bytes,
1278 qiov, qiov_offset, flags);
1279 break;
1281 case MIRROR_METHOD_ZERO:
1282 assert(!qiov);
1283 ret = blk_co_pwrite_zeroes(job->target, offset, bytes, flags);
1284 break;
1286 case MIRROR_METHOD_DISCARD:
1287 assert(!qiov);
1288 ret = blk_co_pdiscard(job->target, offset, bytes);
1289 break;
1291 default:
1292 abort();
1295 if (ret >= 0) {
1296 job_progress_update(&job->common.job, bytes);
1297 } else {
1298 BlockErrorAction action;
1301 * We failed, so we should mark dirty the whole area, aligned up.
1302 * Note that we don't care about shrunk tails if any: they were dirty
1303 * at function start, and they must be still dirty, as we've locked
1304 * the region for in-flight op.
1306 bitmap_offset = QEMU_ALIGN_DOWN(offset, job->granularity);
1307 bitmap_end = QEMU_ALIGN_UP(offset + bytes, job->granularity);
1308 bdrv_set_dirty_bitmap(job->dirty_bitmap, bitmap_offset,
1309 bitmap_end - bitmap_offset);
1310 job->actively_synced = false;
1312 action = mirror_error_action(job, false, -ret);
1313 if (action == BLOCK_ERROR_ACTION_REPORT) {
1314 if (!job->ret) {
1315 job->ret = ret;
1321 static MirrorOp *coroutine_fn active_write_prepare(MirrorBlockJob *s,
1322 uint64_t offset,
1323 uint64_t bytes)
1325 MirrorOp *op;
1326 uint64_t start_chunk = offset / s->granularity;
1327 uint64_t end_chunk = DIV_ROUND_UP(offset + bytes, s->granularity);
1329 op = g_new(MirrorOp, 1);
1330 *op = (MirrorOp){
1331 .s = s,
1332 .offset = offset,
1333 .bytes = bytes,
1334 .is_active_write = true,
1335 .is_in_flight = true,
1337 qemu_co_queue_init(&op->waiting_requests);
1338 QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next);
1340 s->in_active_write_counter++;
1342 mirror_wait_on_conflicts(op, s, offset, bytes);
1344 bitmap_set(s->in_flight_bitmap, start_chunk, end_chunk - start_chunk);
1346 return op;
1349 static void coroutine_fn active_write_settle(MirrorOp *op)
1351 uint64_t start_chunk = op->offset / op->s->granularity;
1352 uint64_t end_chunk = DIV_ROUND_UP(op->offset + op->bytes,
1353 op->s->granularity);
1355 if (!--op->s->in_active_write_counter && op->s->actively_synced) {
1356 BdrvChild *source = op->s->mirror_top_bs->backing;
1358 if (QLIST_FIRST(&source->bs->parents) == source &&
1359 QLIST_NEXT(source, next_parent) == NULL)
1361 /* Assert that we are back in sync once all active write
1362 * operations are settled.
1363 * Note that we can only assert this if the mirror node
1364 * is the source node's only parent. */
1365 assert(!bdrv_get_dirty_count(op->s->dirty_bitmap));
1368 bitmap_clear(op->s->in_flight_bitmap, start_chunk, end_chunk - start_chunk);
1369 QTAILQ_REMOVE(&op->s->ops_in_flight, op, next);
1370 qemu_co_queue_restart_all(&op->waiting_requests);
1371 g_free(op);
1374 static int coroutine_fn bdrv_mirror_top_preadv(BlockDriverState *bs,
1375 uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags)
1377 return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags);
1380 static int coroutine_fn bdrv_mirror_top_do_write(BlockDriverState *bs,
1381 MirrorMethod method, uint64_t offset, uint64_t bytes, QEMUIOVector *qiov,
1382 int flags)
1384 MirrorOp *op = NULL;
1385 MirrorBDSOpaque *s = bs->opaque;
1386 int ret = 0;
1387 bool copy_to_target;
1389 copy_to_target = s->job->ret >= 0 &&
1390 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING;
1392 if (copy_to_target) {
1393 op = active_write_prepare(s->job, offset, bytes);
1396 switch (method) {
1397 case MIRROR_METHOD_COPY:
1398 ret = bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags);
1399 break;
1401 case MIRROR_METHOD_ZERO:
1402 ret = bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags);
1403 break;
1405 case MIRROR_METHOD_DISCARD:
1406 ret = bdrv_co_pdiscard(bs->backing, offset, bytes);
1407 break;
1409 default:
1410 abort();
1413 if (ret < 0) {
1414 goto out;
1417 if (copy_to_target) {
1418 do_sync_target_write(s->job, method, offset, bytes, qiov, flags);
1421 out:
1422 if (copy_to_target) {
1423 active_write_settle(op);
1425 return ret;
1428 static int coroutine_fn bdrv_mirror_top_pwritev(BlockDriverState *bs,
1429 uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags)
1431 MirrorBDSOpaque *s = bs->opaque;
1432 QEMUIOVector bounce_qiov;
1433 void *bounce_buf;
1434 int ret = 0;
1435 bool copy_to_target;
1437 copy_to_target = s->job->ret >= 0 &&
1438 s->job->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING;
1440 if (copy_to_target) {
1441 /* The guest might concurrently modify the data to write; but
1442 * the data on source and destination must match, so we have
1443 * to use a bounce buffer if we are going to write to the
1444 * target now. */
1445 bounce_buf = qemu_blockalign(bs, bytes);
1446 iov_to_buf_full(qiov->iov, qiov->niov, 0, bounce_buf, bytes);
1448 qemu_iovec_init(&bounce_qiov, 1);
1449 qemu_iovec_add(&bounce_qiov, bounce_buf, bytes);
1450 qiov = &bounce_qiov;
1453 ret = bdrv_mirror_top_do_write(bs, MIRROR_METHOD_COPY, offset, bytes, qiov,
1454 flags);
1456 if (copy_to_target) {
1457 qemu_iovec_destroy(&bounce_qiov);
1458 qemu_vfree(bounce_buf);
1461 return ret;
1464 static int coroutine_fn bdrv_mirror_top_flush(BlockDriverState *bs)
1466 if (bs->backing == NULL) {
1467 /* we can be here after failed bdrv_append in mirror_start_job */
1468 return 0;
1470 return bdrv_co_flush(bs->backing->bs);
1473 static int coroutine_fn bdrv_mirror_top_pwrite_zeroes(BlockDriverState *bs,
1474 int64_t offset, int bytes, BdrvRequestFlags flags)
1476 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_ZERO, offset, bytes, NULL,
1477 flags);
1480 static int coroutine_fn bdrv_mirror_top_pdiscard(BlockDriverState *bs,
1481 int64_t offset, int bytes)
1483 return bdrv_mirror_top_do_write(bs, MIRROR_METHOD_DISCARD, offset, bytes,
1484 NULL, 0);
1487 static void bdrv_mirror_top_refresh_filename(BlockDriverState *bs)
1489 if (bs->backing == NULL) {
1490 /* we can be here after failed bdrv_attach_child in
1491 * bdrv_set_backing_hd */
1492 return;
1494 pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
1495 bs->backing->bs->filename);
1498 static void bdrv_mirror_top_child_perm(BlockDriverState *bs, BdrvChild *c,
1499 BdrvChildRole role,
1500 BlockReopenQueue *reopen_queue,
1501 uint64_t perm, uint64_t shared,
1502 uint64_t *nperm, uint64_t *nshared)
1504 MirrorBDSOpaque *s = bs->opaque;
1506 if (s->stop) {
1508 * If the job is to be stopped, we do not need to forward
1509 * anything to the real image.
1511 *nperm = 0;
1512 *nshared = BLK_PERM_ALL;
1513 return;
1516 /* Must be able to forward guest writes to the real image */
1517 *nperm = 0;
1518 if (perm & BLK_PERM_WRITE) {
1519 *nperm |= BLK_PERM_WRITE;
1522 *nshared = BLK_PERM_ALL;
1525 /* Dummy node that provides consistent read to its users without requiring it
1526 * from its backing file and that allows writes on the backing file chain. */
1527 static BlockDriver bdrv_mirror_top = {
1528 .format_name = "mirror_top",
1529 .bdrv_co_preadv = bdrv_mirror_top_preadv,
1530 .bdrv_co_pwritev = bdrv_mirror_top_pwritev,
1531 .bdrv_co_pwrite_zeroes = bdrv_mirror_top_pwrite_zeroes,
1532 .bdrv_co_pdiscard = bdrv_mirror_top_pdiscard,
1533 .bdrv_co_flush = bdrv_mirror_top_flush,
1534 .bdrv_refresh_filename = bdrv_mirror_top_refresh_filename,
1535 .bdrv_child_perm = bdrv_mirror_top_child_perm,
1537 .is_filter = true,
1540 static BlockJob *mirror_start_job(
1541 const char *job_id, BlockDriverState *bs,
1542 int creation_flags, BlockDriverState *target,
1543 const char *replaces, int64_t speed,
1544 uint32_t granularity, int64_t buf_size,
1545 BlockMirrorBackingMode backing_mode,
1546 bool zero_target,
1547 BlockdevOnError on_source_error,
1548 BlockdevOnError on_target_error,
1549 bool unmap,
1550 BlockCompletionFunc *cb,
1551 void *opaque,
1552 const BlockJobDriver *driver,
1553 bool is_none_mode, BlockDriverState *base,
1554 bool auto_complete, const char *filter_node_name,
1555 bool is_mirror, MirrorCopyMode copy_mode,
1556 Error **errp)
1558 MirrorBlockJob *s;
1559 MirrorBDSOpaque *bs_opaque;
1560 BlockDriverState *mirror_top_bs;
1561 bool target_is_backing;
1562 uint64_t target_perms, target_shared_perms;
1563 Error *local_err = NULL;
1564 int ret;
1566 if (granularity == 0) {
1567 granularity = bdrv_get_default_bitmap_granularity(target);
1570 assert(is_power_of_2(granularity));
1572 if (buf_size < 0) {
1573 error_setg(errp, "Invalid parameter 'buf-size'");
1574 return NULL;
1577 if (buf_size == 0) {
1578 buf_size = DEFAULT_MIRROR_BUF_SIZE;
1581 if (bdrv_skip_filters(bs) == bdrv_skip_filters(target)) {
1582 error_setg(errp, "Can't mirror node into itself");
1583 return NULL;
1586 /* In the case of active commit, add dummy driver to provide consistent
1587 * reads on the top, while disabling it in the intermediate nodes, and make
1588 * the backing chain writable. */
1589 mirror_top_bs = bdrv_new_open_driver(&bdrv_mirror_top, filter_node_name,
1590 BDRV_O_RDWR, errp);
1591 if (mirror_top_bs == NULL) {
1592 return NULL;
1594 if (!filter_node_name) {
1595 mirror_top_bs->implicit = true;
1598 /* So that we can always drop this node */
1599 mirror_top_bs->never_freeze = true;
1601 mirror_top_bs->total_sectors = bs->total_sectors;
1602 mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED;
1603 mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
1604 BDRV_REQ_NO_FALLBACK;
1605 bs_opaque = g_new0(MirrorBDSOpaque, 1);
1606 mirror_top_bs->opaque = bs_opaque;
1608 /* bdrv_append takes ownership of the mirror_top_bs reference, need to keep
1609 * it alive until block_job_create() succeeds even if bs has no parent. */
1610 bdrv_ref(mirror_top_bs);
1611 bdrv_drained_begin(bs);
1612 bdrv_append(mirror_top_bs, bs, &local_err);
1613 bdrv_drained_end(bs);
1615 if (local_err) {
1616 bdrv_unref(mirror_top_bs);
1617 error_propagate(errp, local_err);
1618 return NULL;
1621 /* Make sure that the source is not resized while the job is running */
1622 s = block_job_create(job_id, driver, NULL, mirror_top_bs,
1623 BLK_PERM_CONSISTENT_READ,
1624 BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
1625 BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD, speed,
1626 creation_flags, cb, opaque, errp);
1627 if (!s) {
1628 goto fail;
1630 bs_opaque->job = s;
1632 /* The block job now has a reference to this node */
1633 bdrv_unref(mirror_top_bs);
1635 s->mirror_top_bs = mirror_top_bs;
1637 /* No resize for the target either; while the mirror is still running, a
1638 * consistent read isn't necessarily possible. We could possibly allow
1639 * writes and graph modifications, though it would likely defeat the
1640 * purpose of a mirror, so leave them blocked for now.
1642 * In the case of active commit, things look a bit different, though,
1643 * because the target is an already populated backing file in active use.
1644 * We can allow anything except resize there.*/
1646 target_perms = BLK_PERM_WRITE;
1647 target_shared_perms = BLK_PERM_WRITE_UNCHANGED;
1649 target_is_backing = bdrv_chain_contains(bs, target);
1650 if (target_is_backing) {
1651 int64_t bs_size, target_size;
1652 bs_size = bdrv_getlength(bs);
1653 if (bs_size < 0) {
1654 error_setg_errno(errp, -bs_size,
1655 "Could not inquire top image size");
1656 goto fail;
1659 target_size = bdrv_getlength(target);
1660 if (target_size < 0) {
1661 error_setg_errno(errp, -target_size,
1662 "Could not inquire base image size");
1663 goto fail;
1666 if (target_size < bs_size) {
1667 target_perms |= BLK_PERM_RESIZE;
1670 target_shared_perms |= BLK_PERM_CONSISTENT_READ
1671 | BLK_PERM_WRITE
1672 | BLK_PERM_GRAPH_MOD;
1673 } else if (bdrv_chain_contains(bs, bdrv_skip_filters(target))) {
1675 * We may want to allow this in the future, but it would
1676 * require taking some extra care.
1678 error_setg(errp, "Cannot mirror to a filter on top of a node in the "
1679 "source's backing chain");
1680 goto fail;
1683 if (backing_mode != MIRROR_LEAVE_BACKING_CHAIN) {
1684 target_perms |= BLK_PERM_GRAPH_MOD;
1687 s->target = blk_new(s->common.job.aio_context,
1688 target_perms, target_shared_perms);
1689 ret = blk_insert_bs(s->target, target, errp);
1690 if (ret < 0) {
1691 goto fail;
1693 if (is_mirror) {
1694 /* XXX: Mirror target could be a NBD server of target QEMU in the case
1695 * of non-shared block migration. To allow migration completion, we
1696 * have to allow "inactivate" of the target BB. When that happens, we
1697 * know the job is drained, and the vcpus are stopped, so no write
1698 * operation will be performed. Block layer already has assertions to
1699 * ensure that. */
1700 blk_set_force_allow_inactivate(s->target);
1702 blk_set_allow_aio_context_change(s->target, true);
1703 blk_set_disable_request_queuing(s->target, true);
1705 s->replaces = g_strdup(replaces);
1706 s->on_source_error = on_source_error;
1707 s->on_target_error = on_target_error;
1708 s->is_none_mode = is_none_mode;
1709 s->backing_mode = backing_mode;
1710 s->zero_target = zero_target;
1711 s->copy_mode = copy_mode;
1712 s->base = base;
1713 s->base_overlay = bdrv_find_overlay(bs, base);
1714 s->granularity = granularity;
1715 s->buf_size = ROUND_UP(buf_size, granularity);
1716 s->unmap = unmap;
1717 if (auto_complete) {
1718 s->should_complete = true;
1721 s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp);
1722 if (!s->dirty_bitmap) {
1723 goto fail;
1725 if (s->copy_mode == MIRROR_COPY_MODE_WRITE_BLOCKING) {
1726 bdrv_disable_dirty_bitmap(s->dirty_bitmap);
1729 ret = block_job_add_bdrv(&s->common, "source", bs, 0,
1730 BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE |
1731 BLK_PERM_CONSISTENT_READ,
1732 errp);
1733 if (ret < 0) {
1734 goto fail;
1737 /* Required permissions are already taken with blk_new() */
1738 block_job_add_bdrv(&s->common, "target", target, 0, BLK_PERM_ALL,
1739 &error_abort);
1741 /* In commit_active_start() all intermediate nodes disappear, so
1742 * any jobs in them must be blocked */
1743 if (target_is_backing) {
1744 BlockDriverState *iter, *filtered_target;
1745 uint64_t iter_shared_perms;
1748 * The topmost node with
1749 * bdrv_skip_filters(filtered_target) == bdrv_skip_filters(target)
1751 filtered_target = bdrv_cow_bs(bdrv_find_overlay(bs, target));
1753 assert(bdrv_skip_filters(filtered_target) ==
1754 bdrv_skip_filters(target));
1757 * XXX BLK_PERM_WRITE needs to be allowed so we don't block
1758 * ourselves at s->base (if writes are blocked for a node, they are
1759 * also blocked for its backing file). The other options would be a
1760 * second filter driver above s->base (== target).
1762 iter_shared_perms = BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE;
1764 for (iter = bdrv_filter_or_cow_bs(bs); iter != target;
1765 iter = bdrv_filter_or_cow_bs(iter))
1767 if (iter == filtered_target) {
1769 * From here on, all nodes are filters on the base.
1770 * This allows us to share BLK_PERM_CONSISTENT_READ.
1772 iter_shared_perms |= BLK_PERM_CONSISTENT_READ;
1775 ret = block_job_add_bdrv(&s->common, "intermediate node", iter, 0,
1776 iter_shared_perms, errp);
1777 if (ret < 0) {
1778 goto fail;
1782 if (bdrv_freeze_backing_chain(mirror_top_bs, target, errp) < 0) {
1783 goto fail;
1787 QTAILQ_INIT(&s->ops_in_flight);
1789 trace_mirror_start(bs, s, opaque);
1790 job_start(&s->common.job);
1792 return &s->common;
1794 fail:
1795 if (s) {
1796 /* Make sure this BDS does not go away until we have completed the graph
1797 * changes below */
1798 bdrv_ref(mirror_top_bs);
1800 g_free(s->replaces);
1801 blk_unref(s->target);
1802 bs_opaque->job = NULL;
1803 if (s->dirty_bitmap) {
1804 bdrv_release_dirty_bitmap(s->dirty_bitmap);
1806 job_early_fail(&s->common.job);
1809 bs_opaque->stop = true;
1810 bdrv_child_refresh_perms(mirror_top_bs, mirror_top_bs->backing,
1811 &error_abort);
1812 bdrv_replace_node(mirror_top_bs, mirror_top_bs->backing->bs, &error_abort);
1814 bdrv_unref(mirror_top_bs);
1816 return NULL;
1819 void mirror_start(const char *job_id, BlockDriverState *bs,
1820 BlockDriverState *target, const char *replaces,
1821 int creation_flags, int64_t speed,
1822 uint32_t granularity, int64_t buf_size,
1823 MirrorSyncMode mode, BlockMirrorBackingMode backing_mode,
1824 bool zero_target,
1825 BlockdevOnError on_source_error,
1826 BlockdevOnError on_target_error,
1827 bool unmap, const char *filter_node_name,
1828 MirrorCopyMode copy_mode, Error **errp)
1830 bool is_none_mode;
1831 BlockDriverState *base;
1833 if ((mode == MIRROR_SYNC_MODE_INCREMENTAL) ||
1834 (mode == MIRROR_SYNC_MODE_BITMAP)) {
1835 error_setg(errp, "Sync mode '%s' not supported",
1836 MirrorSyncMode_str(mode));
1837 return;
1839 is_none_mode = mode == MIRROR_SYNC_MODE_NONE;
1840 base = mode == MIRROR_SYNC_MODE_TOP ? bdrv_backing_chain_next(bs) : NULL;
1841 mirror_start_job(job_id, bs, creation_flags, target, replaces,
1842 speed, granularity, buf_size, backing_mode, zero_target,
1843 on_source_error, on_target_error, unmap, NULL, NULL,
1844 &mirror_job_driver, is_none_mode, base, false,
1845 filter_node_name, true, copy_mode, errp);
1848 BlockJob *commit_active_start(const char *job_id, BlockDriverState *bs,
1849 BlockDriverState *base, int creation_flags,
1850 int64_t speed, BlockdevOnError on_error,
1851 const char *filter_node_name,
1852 BlockCompletionFunc *cb, void *opaque,
1853 bool auto_complete, Error **errp)
1855 bool base_read_only;
1856 Error *local_err = NULL;
1857 BlockJob *ret;
1859 base_read_only = bdrv_is_read_only(base);
1861 if (base_read_only) {
1862 if (bdrv_reopen_set_read_only(base, false, errp) < 0) {
1863 return NULL;
1867 ret = mirror_start_job(
1868 job_id, bs, creation_flags, base, NULL, speed, 0, 0,
1869 MIRROR_LEAVE_BACKING_CHAIN, false,
1870 on_error, on_error, true, cb, opaque,
1871 &commit_active_job_driver, false, base, auto_complete,
1872 filter_node_name, false, MIRROR_COPY_MODE_BACKGROUND,
1873 &local_err);
1874 if (local_err) {
1875 error_propagate(errp, local_err);
1876 goto error_restore_flags;
1879 return ret;
1881 error_restore_flags:
1882 /* ignore error and errp for bdrv_reopen, because we want to propagate
1883 * the original error */
1884 if (base_read_only) {
1885 bdrv_reopen_set_read_only(base, true, NULL);
1887 return NULL;