diff options
Diffstat (limited to 'block/mirror.c')
| -rw-r--r-- | block/mirror.c | 235 |
1 files changed, 235 insertions, 0 deletions
diff --git a/block/mirror.c b/block/mirror.c new file mode 100644 index 0000000000..b353798e8f --- /dev/null +++ b/block/mirror.c @@ -0,0 +1,235 @@ +/* + * Image mirroring + * + * Copyright Red Hat, Inc. 2012 + * + * Authors: + * Paolo Bonzini <pbonzini@redhat.com> + * + * This work is licensed under the terms of the GNU LGPL, version 2 or later. + * See the COPYING.LIB file in the top-level directory. + * + */ + +#include "trace.h" +#include "blockjob.h" +#include "block_int.h" +#include "qemu/ratelimit.h" + +enum { + /* + * Size of data buffer for populating the image file. This should be large + * enough to process multiple clusters in a single call, so that populating + * contiguous regions of the image is efficient. + */ + BLOCK_SIZE = 512 * BDRV_SECTORS_PER_DIRTY_CHUNK, /* in bytes */ +}; + +#define SLICE_TIME 100000000ULL /* ns */ + +typedef struct MirrorBlockJob { + BlockJob common; + RateLimit limit; + BlockDriverState *target; + MirrorSyncMode mode; + int64_t sector_num; + uint8_t *buf; +} MirrorBlockJob; + +static int coroutine_fn mirror_iteration(MirrorBlockJob *s) +{ + BlockDriverState *source = s->common.bs; + BlockDriverState *target = s->target; + QEMUIOVector qiov; + int ret, nb_sectors; + int64_t end; + struct iovec iov; + + end = s->common.len >> BDRV_SECTOR_BITS; + s->sector_num = bdrv_get_next_dirty(source, s->sector_num); + nb_sectors = MIN(BDRV_SECTORS_PER_DIRTY_CHUNK, end - s->sector_num); + bdrv_reset_dirty(source, s->sector_num, nb_sectors); + + /* Copy the dirty cluster. */ + iov.iov_base = s->buf; + iov.iov_len = nb_sectors * 512; + qemu_iovec_init_external(&qiov, &iov, 1); + + trace_mirror_one_iteration(s, s->sector_num, nb_sectors); + ret = bdrv_co_readv(source, s->sector_num, nb_sectors, &qiov); + if (ret < 0) { + return ret; + } + return bdrv_co_writev(target, s->sector_num, nb_sectors, &qiov); +} + +static void coroutine_fn mirror_run(void *opaque) +{ + MirrorBlockJob *s = opaque; + BlockDriverState *bs = s->common.bs; + int64_t sector_num, end; + int ret = 0; + int n; + bool synced = false; + + if (block_job_is_cancelled(&s->common)) { + goto immediate_exit; + } + + s->common.len = bdrv_getlength(bs); + if (s->common.len < 0) { + block_job_completed(&s->common, s->common.len); + return; + } + + end = s->common.len >> BDRV_SECTOR_BITS; + s->buf = qemu_blockalign(bs, BLOCK_SIZE); + + if (s->mode != MIRROR_SYNC_MODE_NONE) { + /* First part, loop on the sectors and initialize the dirty bitmap. */ + BlockDriverState *base; + base = s->mode == MIRROR_SYNC_MODE_FULL ? NULL : bs->backing_hd; + for (sector_num = 0; sector_num < end; ) { + int64_t next = (sector_num | (BDRV_SECTORS_PER_DIRTY_CHUNK - 1)) + 1; + ret = bdrv_co_is_allocated_above(bs, base, + sector_num, next - sector_num, &n); + + if (ret < 0) { + goto immediate_exit; + } + + assert(n > 0); + if (ret == 1) { + bdrv_set_dirty(bs, sector_num, n); + sector_num = next; + } else { + sector_num += n; + } + } + } + + s->sector_num = -1; + for (;;) { + uint64_t delay_ns; + int64_t cnt; + bool should_complete; + + cnt = bdrv_get_dirty_count(bs); + if (cnt != 0) { + ret = mirror_iteration(s); + if (ret < 0) { + goto immediate_exit; + } + cnt = bdrv_get_dirty_count(bs); + } + + should_complete = false; + if (cnt == 0) { + trace_mirror_before_flush(s); + ret = bdrv_flush(s->target); + if (ret < 0) { + goto immediate_exit; + } + + /* We're out of the streaming phase. From now on, if the job + * is cancelled we will actually complete all pending I/O and + * report completion. This way, block-job-cancel will leave + * the target in a consistent state. + */ + synced = true; + s->common.offset = end * BDRV_SECTOR_SIZE; + should_complete = block_job_is_cancelled(&s->common); + cnt = bdrv_get_dirty_count(bs); + } + + if (cnt == 0 && should_complete) { + /* The dirty bitmap is not updated while operations are pending. + * If we're about to exit, wait for pending operations before + * calling bdrv_get_dirty_count(bs), or we may exit while the + * source has dirty data to copy! + * + * Note that I/O can be submitted by the guest while + * mirror_populate runs. + */ + trace_mirror_before_drain(s, cnt); + bdrv_drain_all(); + cnt = bdrv_get_dirty_count(bs); + } + + ret = 0; + trace_mirror_before_sleep(s, cnt, synced); + if (!synced) { + /* Publish progress */ + s->common.offset = end * BDRV_SECTOR_SIZE - cnt * BLOCK_SIZE; + + if (s->common.speed) { + delay_ns = ratelimit_calculate_delay(&s->limit, BDRV_SECTORS_PER_DIRTY_CHUNK); + } else { + delay_ns = 0; + } + + /* Note that even when no rate limit is applied we need to yield + * with no pending I/O here so that qemu_aio_flush() returns. + */ + block_job_sleep_ns(&s->common, rt_clock, delay_ns); + if (block_job_is_cancelled(&s->common)) { + break; + } + } else if (!should_complete) { + delay_ns = (cnt == 0 ? SLICE_TIME : 0); + block_job_sleep_ns(&s->common, rt_clock, delay_ns); + } else if (cnt == 0) { + /* The two disks are in sync. Exit and report successful + * completion. + */ + assert(QLIST_EMPTY(&bs->tracked_requests)); + s->common.cancelled = false; + break; + } + } + +immediate_exit: + g_free(s->buf); + bdrv_set_dirty_tracking(bs, false); + bdrv_close(s->target); + bdrv_delete(s->target); + block_job_completed(&s->common, ret); +} + +static void mirror_set_speed(BlockJob *job, int64_t speed, Error **errp) +{ + MirrorBlockJob *s = container_of(job, MirrorBlockJob, common); + + if (speed < 0) { + error_set(errp, QERR_INVALID_PARAMETER, "speed"); + return; + } + ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME); +} + +static BlockJobType mirror_job_type = { + .instance_size = sizeof(MirrorBlockJob), + .job_type = "mirror", + .set_speed = mirror_set_speed, +}; + +void mirror_start(BlockDriverState *bs, BlockDriverState *target, + int64_t speed, MirrorSyncMode mode, + BlockDriverCompletionFunc *cb, + void *opaque, Error **errp) +{ + MirrorBlockJob *s; + + s = block_job_create(&mirror_job_type, bs, speed, cb, opaque, errp); + if (!s) { + return; + } + + s->target = target; + s->mode = mode; + bdrv_set_dirty_tracking(bs, true); + bdrv_set_enable_write_cache(s->target, true); + s->common.co = qemu_coroutine_create(mirror_run); + trace_mirror_start(bs, s, s->common.co, opaque); + qemu_coroutine_enter(s->common.co, s); +} |