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/*
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* Image mirroring
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*
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* Copyright Red Hat, Inc. 2012
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*
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* Authors:
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* Paolo Bonzini <pbonzini@redhat.com>
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*
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* This work is licensed under the terms of the GNU LGPL, version 2 or later.
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* See the COPYING.LIB file in the top-level directory.
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*
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*/
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#include "trace.h" |
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#include "block/blockjob.h" |
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#include "block/block_int.h" |
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#include "qemu/ratelimit.h" |
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#include "qemu/bitmap.h" |
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|
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#define SLICE_TIME 100000000ULL /* ns */ |
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#define MAX_IN_FLIGHT 16 |
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/* The mirroring buffer is a list of granularity-sized chunks.
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* Free chunks are organized in a list.
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*/
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typedef struct MirrorBuffer { |
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QSIMPLEQ_ENTRY(MirrorBuffer) next; |
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} MirrorBuffer; |
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|
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typedef struct MirrorBlockJob { |
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BlockJob common; |
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RateLimit limit; |
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BlockDriverState *target; |
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BlockDriverState *base; |
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MirrorSyncMode mode; |
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BlockdevOnError on_source_error, on_target_error; |
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bool synced;
|
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bool should_complete;
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int64_t sector_num; |
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int64_t granularity; |
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size_t buf_size; |
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unsigned long *cow_bitmap; |
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BdrvDirtyBitmap *dirty_bitmap; |
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HBitmapIter hbi; |
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uint8_t *buf; |
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QSIMPLEQ_HEAD(, MirrorBuffer) buf_free; |
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int buf_free_count;
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|
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unsigned long *in_flight_bitmap; |
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int in_flight;
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int ret;
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} MirrorBlockJob; |
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|
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typedef struct MirrorOp { |
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MirrorBlockJob *s; |
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QEMUIOVector qiov; |
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int64_t sector_num; |
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int nb_sectors;
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} MirrorOp; |
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|
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static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, |
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int error)
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{ |
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s->synced = false;
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if (read) {
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return block_job_error_action(&s->common, s->common.bs,
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s->on_source_error, true, error);
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} else {
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return block_job_error_action(&s->common, s->target,
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s->on_target_error, false, error);
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} |
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} |
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|
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static void mirror_iteration_done(MirrorOp *op, int ret) |
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{ |
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MirrorBlockJob *s = op->s; |
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struct iovec *iov;
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int64_t chunk_num; |
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int i, nb_chunks, sectors_per_chunk;
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|
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trace_mirror_iteration_done(s, op->sector_num, op->nb_sectors, ret); |
82 |
|
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s->in_flight--; |
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iov = op->qiov.iov; |
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for (i = 0; i < op->qiov.niov; i++) { |
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MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base; |
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QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next); |
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s->buf_free_count++; |
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} |
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|
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sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; |
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chunk_num = op->sector_num / sectors_per_chunk; |
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nb_chunks = op->nb_sectors / sectors_per_chunk; |
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bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks); |
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if (s->cow_bitmap && ret >= 0) { |
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bitmap_set(s->cow_bitmap, chunk_num, nb_chunks); |
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} |
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|
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g_slice_free(MirrorOp, op); |
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qemu_coroutine_enter(s->common.co, NULL);
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} |
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static void mirror_write_complete(void *opaque, int ret) |
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{ |
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MirrorOp *op = opaque; |
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MirrorBlockJob *s = op->s; |
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if (ret < 0) { |
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BlockDriverState *source = s->common.bs; |
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BlockErrorAction action; |
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|
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bdrv_set_dirty(source, op->sector_num, op->nb_sectors); |
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action = mirror_error_action(s, false, -ret);
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if (action == BDRV_ACTION_REPORT && s->ret >= 0) { |
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s->ret = ret; |
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} |
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} |
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mirror_iteration_done(op, ret); |
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} |
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|
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static void mirror_read_complete(void *opaque, int ret) |
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{ |
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MirrorOp *op = opaque; |
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MirrorBlockJob *s = op->s; |
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if (ret < 0) { |
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BlockDriverState *source = s->common.bs; |
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BlockErrorAction action; |
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bdrv_set_dirty(source, op->sector_num, op->nb_sectors); |
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action = mirror_error_action(s, true, -ret);
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if (action == BDRV_ACTION_REPORT && s->ret >= 0) { |
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s->ret = ret; |
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} |
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mirror_iteration_done(op, ret); |
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return;
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} |
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bdrv_aio_writev(s->target, op->sector_num, &op->qiov, op->nb_sectors, |
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mirror_write_complete, op); |
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} |
140 |
|
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static void coroutine_fn mirror_iteration(MirrorBlockJob *s) |
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{ |
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BlockDriverState *source = s->common.bs; |
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int nb_sectors, sectors_per_chunk, nb_chunks;
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int64_t end, sector_num, next_chunk, next_sector, hbitmap_next_sector; |
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MirrorOp *op; |
147 |
|
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s->sector_num = hbitmap_iter_next(&s->hbi); |
149 |
if (s->sector_num < 0) { |
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bdrv_dirty_iter_init(source, s->dirty_bitmap, &s->hbi); |
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s->sector_num = hbitmap_iter_next(&s->hbi); |
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trace_mirror_restart_iter(s, |
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bdrv_get_dirty_count(source, s->dirty_bitmap)); |
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assert(s->sector_num >= 0);
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} |
156 |
|
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hbitmap_next_sector = s->sector_num; |
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sector_num = s->sector_num; |
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sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; |
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end = s->common.len >> BDRV_SECTOR_BITS; |
161 |
|
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/* Extend the QEMUIOVector to include all adjacent blocks that will
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* be copied in this operation.
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*
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* We have to do this if we have no backing file yet in the destination,
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* and the cluster size is very large. Then we need to do COW ourselves.
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* The first time a cluster is copied, copy it entirely. Note that,
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* because both the granularity and the cluster size are powers of two,
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* the number of sectors to copy cannot exceed one cluster.
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*
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* We also want to extend the QEMUIOVector to include more adjacent
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* dirty blocks if possible, to limit the number of I/O operations and
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* run efficiently even with a small granularity.
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*/
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nb_chunks = 0;
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nb_sectors = 0;
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next_sector = sector_num; |
178 |
next_chunk = sector_num / sectors_per_chunk; |
179 |
|
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/* Wait for I/O to this cluster (from a previous iteration) to be done. */
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while (test_bit(next_chunk, s->in_flight_bitmap)) {
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trace_mirror_yield_in_flight(s, sector_num, s->in_flight); |
183 |
qemu_coroutine_yield(); |
184 |
} |
185 |
|
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do {
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int added_sectors, added_chunks;
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if (!bdrv_get_dirty(source, s->dirty_bitmap, next_sector) ||
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test_bit(next_chunk, s->in_flight_bitmap)) { |
191 |
assert(nb_sectors > 0);
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break;
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} |
194 |
|
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added_sectors = sectors_per_chunk; |
196 |
if (s->cow_bitmap && !test_bit(next_chunk, s->cow_bitmap)) {
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bdrv_round_to_clusters(s->target, |
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next_sector, added_sectors, |
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&next_sector, &added_sectors); |
200 |
|
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/* On the first iteration, the rounding may make us copy
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* sectors before the first dirty one.
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*/
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if (next_sector < sector_num) {
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assert(nb_sectors == 0);
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sector_num = next_sector; |
207 |
next_chunk = next_sector / sectors_per_chunk; |
208 |
} |
209 |
} |
210 |
|
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added_sectors = MIN(added_sectors, end - (sector_num + nb_sectors)); |
212 |
added_chunks = (added_sectors + sectors_per_chunk - 1) / sectors_per_chunk;
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|
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/* When doing COW, it may happen that there is not enough space for
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* a full cluster. Wait if that is the case.
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*/
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while (nb_chunks == 0 && s->buf_free_count < added_chunks) { |
218 |
trace_mirror_yield_buf_busy(s, nb_chunks, s->in_flight); |
219 |
qemu_coroutine_yield(); |
220 |
} |
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if (s->buf_free_count < nb_chunks + added_chunks) {
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trace_mirror_break_buf_busy(s, nb_chunks, s->in_flight); |
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break;
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} |
225 |
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/* We have enough free space to copy these sectors. */
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bitmap_set(s->in_flight_bitmap, next_chunk, added_chunks); |
228 |
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nb_sectors += added_sectors; |
230 |
nb_chunks += added_chunks; |
231 |
next_sector += added_sectors; |
232 |
next_chunk += added_chunks; |
233 |
} while (next_sector < end);
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|
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/* Allocate a MirrorOp that is used as an AIO callback. */
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op = g_slice_new(MirrorOp); |
237 |
op->s = s; |
238 |
op->sector_num = sector_num; |
239 |
op->nb_sectors = nb_sectors; |
240 |
|
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/* Now make a QEMUIOVector taking enough granularity-sized chunks
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* from s->buf_free.
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*/
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qemu_iovec_init(&op->qiov, nb_chunks); |
245 |
next_sector = sector_num; |
246 |
while (nb_chunks-- > 0) { |
247 |
MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free); |
248 |
QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next); |
249 |
s->buf_free_count--; |
250 |
qemu_iovec_add(&op->qiov, buf, s->granularity); |
251 |
|
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/* Advance the HBitmapIter in parallel, so that we do not examine
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* the same sector twice.
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*/
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if (next_sector > hbitmap_next_sector
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&& bdrv_get_dirty(source, s->dirty_bitmap, next_sector)) { |
257 |
hbitmap_next_sector = hbitmap_iter_next(&s->hbi); |
258 |
} |
259 |
|
260 |
next_sector += sectors_per_chunk; |
261 |
} |
262 |
|
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bdrv_reset_dirty(source, sector_num, nb_sectors); |
264 |
|
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/* Copy the dirty cluster. */
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s->in_flight++; |
267 |
trace_mirror_one_iteration(s, sector_num, nb_sectors); |
268 |
bdrv_aio_readv(source, sector_num, &op->qiov, nb_sectors, |
269 |
mirror_read_complete, op); |
270 |
} |
271 |
|
272 |
static void mirror_free_init(MirrorBlockJob *s) |
273 |
{ |
274 |
int granularity = s->granularity;
|
275 |
size_t buf_size = s->buf_size; |
276 |
uint8_t *buf = s->buf; |
277 |
|
278 |
assert(s->buf_free_count == 0);
|
279 |
QSIMPLEQ_INIT(&s->buf_free); |
280 |
while (buf_size != 0) { |
281 |
MirrorBuffer *cur = (MirrorBuffer *)buf; |
282 |
QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); |
283 |
s->buf_free_count++; |
284 |
buf_size -= granularity; |
285 |
buf += granularity; |
286 |
} |
287 |
} |
288 |
|
289 |
static void mirror_drain(MirrorBlockJob *s) |
290 |
{ |
291 |
while (s->in_flight > 0) { |
292 |
qemu_coroutine_yield(); |
293 |
} |
294 |
} |
295 |
|
296 |
static void coroutine_fn mirror_run(void *opaque) |
297 |
{ |
298 |
MirrorBlockJob *s = opaque; |
299 |
BlockDriverState *bs = s->common.bs; |
300 |
int64_t sector_num, end, sectors_per_chunk, length; |
301 |
uint64_t last_pause_ns; |
302 |
BlockDriverInfo bdi; |
303 |
char backing_filename[1024]; |
304 |
int ret = 0; |
305 |
int n;
|
306 |
|
307 |
if (block_job_is_cancelled(&s->common)) {
|
308 |
goto immediate_exit;
|
309 |
} |
310 |
|
311 |
s->common.len = bdrv_getlength(bs); |
312 |
if (s->common.len <= 0) { |
313 |
block_job_completed(&s->common, s->common.len); |
314 |
return;
|
315 |
} |
316 |
|
317 |
length = (bdrv_getlength(bs) + s->granularity - 1) / s->granularity;
|
318 |
s->in_flight_bitmap = bitmap_new(length); |
319 |
|
320 |
/* If we have no backing file yet in the destination, we cannot let
|
321 |
* the destination do COW. Instead, we copy sectors around the
|
322 |
* dirty data if needed. We need a bitmap to do that.
|
323 |
*/
|
324 |
bdrv_get_backing_filename(s->target, backing_filename, |
325 |
sizeof(backing_filename));
|
326 |
if (backing_filename[0] && !s->target->backing_hd) { |
327 |
bdrv_get_info(s->target, &bdi); |
328 |
if (s->granularity < bdi.cluster_size) {
|
329 |
s->buf_size = MAX(s->buf_size, bdi.cluster_size); |
330 |
s->cow_bitmap = bitmap_new(length); |
331 |
} |
332 |
} |
333 |
|
334 |
end = s->common.len >> BDRV_SECTOR_BITS; |
335 |
s->buf = qemu_blockalign(bs, s->buf_size); |
336 |
sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; |
337 |
mirror_free_init(s); |
338 |
|
339 |
if (s->mode != MIRROR_SYNC_MODE_NONE) {
|
340 |
/* First part, loop on the sectors and initialize the dirty bitmap. */
|
341 |
BlockDriverState *base = s->base; |
342 |
for (sector_num = 0; sector_num < end; ) { |
343 |
int64_t next = (sector_num | (sectors_per_chunk - 1)) + 1; |
344 |
ret = bdrv_is_allocated_above(bs, base, |
345 |
sector_num, next - sector_num, &n); |
346 |
|
347 |
if (ret < 0) { |
348 |
goto immediate_exit;
|
349 |
} |
350 |
|
351 |
assert(n > 0);
|
352 |
if (ret == 1) { |
353 |
bdrv_set_dirty(bs, sector_num, n); |
354 |
sector_num = next; |
355 |
} else {
|
356 |
sector_num += n; |
357 |
} |
358 |
} |
359 |
} |
360 |
|
361 |
bdrv_dirty_iter_init(bs, s->dirty_bitmap, &s->hbi); |
362 |
last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); |
363 |
for (;;) {
|
364 |
uint64_t delay_ns; |
365 |
int64_t cnt; |
366 |
bool should_complete;
|
367 |
|
368 |
if (s->ret < 0) { |
369 |
ret = s->ret; |
370 |
goto immediate_exit;
|
371 |
} |
372 |
|
373 |
cnt = bdrv_get_dirty_count(bs, s->dirty_bitmap); |
374 |
|
375 |
/* Note that even when no rate limit is applied we need to yield
|
376 |
* periodically with no pending I/O so that qemu_aio_flush() returns.
|
377 |
* We do so every SLICE_TIME nanoseconds, or when there is an error,
|
378 |
* or when the source is clean, whichever comes first.
|
379 |
*/
|
380 |
if (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - last_pause_ns < SLICE_TIME &&
|
381 |
s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { |
382 |
if (s->in_flight == MAX_IN_FLIGHT || s->buf_free_count == 0 || |
383 |
(cnt == 0 && s->in_flight > 0)) { |
384 |
trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt); |
385 |
qemu_coroutine_yield(); |
386 |
continue;
|
387 |
} else if (cnt != 0) { |
388 |
mirror_iteration(s); |
389 |
continue;
|
390 |
} |
391 |
} |
392 |
|
393 |
should_complete = false;
|
394 |
if (s->in_flight == 0 && cnt == 0) { |
395 |
trace_mirror_before_flush(s); |
396 |
ret = bdrv_flush(s->target); |
397 |
if (ret < 0) { |
398 |
if (mirror_error_action(s, false, -ret) == BDRV_ACTION_REPORT) { |
399 |
goto immediate_exit;
|
400 |
} |
401 |
} else {
|
402 |
/* We're out of the streaming phase. From now on, if the job
|
403 |
* is cancelled we will actually complete all pending I/O and
|
404 |
* report completion. This way, block-job-cancel will leave
|
405 |
* the target in a consistent state.
|
406 |
*/
|
407 |
s->common.offset = end * BDRV_SECTOR_SIZE; |
408 |
if (!s->synced) {
|
409 |
block_job_ready(&s->common); |
410 |
s->synced = true;
|
411 |
} |
412 |
|
413 |
should_complete = s->should_complete || |
414 |
block_job_is_cancelled(&s->common); |
415 |
cnt = bdrv_get_dirty_count(bs, s->dirty_bitmap); |
416 |
} |
417 |
} |
418 |
|
419 |
if (cnt == 0 && should_complete) { |
420 |
/* The dirty bitmap is not updated while operations are pending.
|
421 |
* If we're about to exit, wait for pending operations before
|
422 |
* calling bdrv_get_dirty_count(bs), or we may exit while the
|
423 |
* source has dirty data to copy!
|
424 |
*
|
425 |
* Note that I/O can be submitted by the guest while
|
426 |
* mirror_populate runs.
|
427 |
*/
|
428 |
trace_mirror_before_drain(s, cnt); |
429 |
bdrv_drain_all(); |
430 |
cnt = bdrv_get_dirty_count(bs, s->dirty_bitmap); |
431 |
} |
432 |
|
433 |
ret = 0;
|
434 |
trace_mirror_before_sleep(s, cnt, s->synced); |
435 |
if (!s->synced) {
|
436 |
/* Publish progress */
|
437 |
s->common.offset = (end - cnt) * BDRV_SECTOR_SIZE; |
438 |
|
439 |
if (s->common.speed) {
|
440 |
delay_ns = ratelimit_calculate_delay(&s->limit, sectors_per_chunk); |
441 |
} else {
|
442 |
delay_ns = 0;
|
443 |
} |
444 |
|
445 |
block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); |
446 |
if (block_job_is_cancelled(&s->common)) {
|
447 |
break;
|
448 |
} |
449 |
} else if (!should_complete) { |
450 |
delay_ns = (s->in_flight == 0 && cnt == 0 ? SLICE_TIME : 0); |
451 |
block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns); |
452 |
} else if (cnt == 0) { |
453 |
/* The two disks are in sync. Exit and report successful
|
454 |
* completion.
|
455 |
*/
|
456 |
assert(QLIST_EMPTY(&bs->tracked_requests)); |
457 |
s->common.cancelled = false;
|
458 |
break;
|
459 |
} |
460 |
last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); |
461 |
} |
462 |
|
463 |
immediate_exit:
|
464 |
if (s->in_flight > 0) { |
465 |
/* We get here only if something went wrong. Either the job failed,
|
466 |
* or it was cancelled prematurely so that we do not guarantee that
|
467 |
* the target is a copy of the source.
|
468 |
*/
|
469 |
assert(ret < 0 || (!s->synced && block_job_is_cancelled(&s->common)));
|
470 |
mirror_drain(s); |
471 |
} |
472 |
|
473 |
assert(s->in_flight == 0);
|
474 |
qemu_vfree(s->buf); |
475 |
g_free(s->cow_bitmap); |
476 |
g_free(s->in_flight_bitmap); |
477 |
bdrv_release_dirty_bitmap(bs, s->dirty_bitmap); |
478 |
bdrv_iostatus_disable(s->target); |
479 |
if (s->should_complete && ret == 0) { |
480 |
if (bdrv_get_flags(s->target) != bdrv_get_flags(s->common.bs)) {
|
481 |
bdrv_reopen(s->target, bdrv_get_flags(s->common.bs), NULL);
|
482 |
} |
483 |
bdrv_swap(s->target, s->common.bs); |
484 |
} |
485 |
bdrv_unref(s->target); |
486 |
block_job_completed(&s->common, ret); |
487 |
} |
488 |
|
489 |
static void mirror_set_speed(BlockJob *job, int64_t speed, Error **errp) |
490 |
{ |
491 |
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); |
492 |
|
493 |
if (speed < 0) { |
494 |
error_set(errp, QERR_INVALID_PARAMETER, "speed");
|
495 |
return;
|
496 |
} |
497 |
ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME); |
498 |
} |
499 |
|
500 |
static void mirror_iostatus_reset(BlockJob *job) |
501 |
{ |
502 |
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); |
503 |
|
504 |
bdrv_iostatus_reset(s->target); |
505 |
} |
506 |
|
507 |
static void mirror_complete(BlockJob *job, Error **errp) |
508 |
{ |
509 |
MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); |
510 |
Error *local_err = NULL;
|
511 |
int ret;
|
512 |
|
513 |
ret = bdrv_open_backing_file(s->target, NULL, &local_err);
|
514 |
if (ret < 0) { |
515 |
char backing_filename[PATH_MAX];
|
516 |
bdrv_get_full_backing_filename(s->target, backing_filename, |
517 |
sizeof(backing_filename));
|
518 |
error_propagate(errp, local_err); |
519 |
return;
|
520 |
} |
521 |
if (!s->synced) {
|
522 |
error_set(errp, QERR_BLOCK_JOB_NOT_READY, job->bs->device_name); |
523 |
return;
|
524 |
} |
525 |
|
526 |
s->should_complete = true;
|
527 |
block_job_resume(job); |
528 |
} |
529 |
|
530 |
static const BlockJobDriver mirror_job_driver = { |
531 |
.instance_size = sizeof(MirrorBlockJob),
|
532 |
.job_type = BLOCK_JOB_TYPE_MIRROR, |
533 |
.set_speed = mirror_set_speed, |
534 |
.iostatus_reset= mirror_iostatus_reset, |
535 |
.complete = mirror_complete, |
536 |
}; |
537 |
|
538 |
void mirror_start(BlockDriverState *bs, BlockDriverState *target,
|
539 |
int64_t speed, int64_t granularity, int64_t buf_size, |
540 |
MirrorSyncMode mode, BlockdevOnError on_source_error, |
541 |
BlockdevOnError on_target_error, |
542 |
BlockDriverCompletionFunc *cb, |
543 |
void *opaque, Error **errp)
|
544 |
{ |
545 |
MirrorBlockJob *s; |
546 |
BlockDriverState *base = NULL;
|
547 |
|
548 |
if (granularity == 0) { |
549 |
/* Choose the default granularity based on the target file's cluster
|
550 |
* size, clamped between 4k and 64k. */
|
551 |
BlockDriverInfo bdi; |
552 |
if (bdrv_get_info(target, &bdi) >= 0 && bdi.cluster_size != 0) { |
553 |
granularity = MAX(4096, bdi.cluster_size);
|
554 |
granularity = MIN(65536, granularity);
|
555 |
} else {
|
556 |
granularity = 65536;
|
557 |
} |
558 |
} |
559 |
|
560 |
assert ((granularity & (granularity - 1)) == 0); |
561 |
|
562 |
if ((on_source_error == BLOCKDEV_ON_ERROR_STOP ||
|
563 |
on_source_error == BLOCKDEV_ON_ERROR_ENOSPC) && |
564 |
!bdrv_iostatus_is_enabled(bs)) { |
565 |
error_set(errp, QERR_INVALID_PARAMETER, "on-source-error");
|
566 |
return;
|
567 |
} |
568 |
|
569 |
if (mode == MIRROR_SYNC_MODE_TOP) {
|
570 |
base = bs->backing_hd; |
571 |
} else {
|
572 |
base = NULL;
|
573 |
} |
574 |
|
575 |
s = block_job_create(&mirror_job_driver, bs, speed, cb, opaque, errp); |
576 |
if (!s) {
|
577 |
return;
|
578 |
} |
579 |
|
580 |
s->on_source_error = on_source_error; |
581 |
s->on_target_error = on_target_error; |
582 |
s->target = target; |
583 |
s->mode = mode; |
584 |
s->base = base; |
585 |
s->granularity = granularity; |
586 |
s->buf_size = MAX(buf_size, granularity); |
587 |
|
588 |
s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity); |
589 |
bdrv_set_enable_write_cache(s->target, true);
|
590 |
bdrv_set_on_error(s->target, on_target_error, on_target_error); |
591 |
bdrv_iostatus_enable(s->target); |
592 |
s->common.co = qemu_coroutine_create(mirror_run); |
593 |
trace_mirror_start(bs, s, s->common.co, opaque); |
594 |
qemu_coroutine_enter(s->common.co, s); |
595 |
} |