diff options
Diffstat (limited to 'block/mirror.c')
-rw-r--r-- | block/mirror.c | 382 |
1 files changed, 322 insertions, 60 deletions
diff --git a/block/mirror.c b/block/mirror.c index 6180aa3..a62ad86 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -15,17 +15,17 @@ #include "block/blockjob.h" #include "block/block_int.h" #include "qemu/ratelimit.h" +#include "qemu/bitmap.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 */ +#define MAX_IN_FLIGHT 16 -#define SLICE_TIME 100000000ULL /* ns */ +/* The mirroring buffer is a list of granularity-sized chunks. + * Free chunks are organized in a list. + */ +typedef struct MirrorBuffer { + QSIMPLEQ_ENTRY(MirrorBuffer) next; +} MirrorBuffer; typedef struct MirrorBlockJob { BlockJob common; @@ -36,9 +36,26 @@ typedef struct MirrorBlockJob { bool synced; bool should_complete; int64_t sector_num; + int64_t granularity; + size_t buf_size; + unsigned long *cow_bitmap; + HBitmapIter hbi; uint8_t *buf; + QSIMPLEQ_HEAD(, MirrorBuffer) buf_free; + int buf_free_count; + + unsigned long *in_flight_bitmap; + int in_flight; + int ret; } MirrorBlockJob; +typedef struct MirrorOp { + MirrorBlockJob *s; + QEMUIOVector qiov; + int64_t sector_num; + int nb_sectors; +} MirrorOp; + static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, int error) { @@ -52,51 +69,234 @@ static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read, } } -static int coroutine_fn mirror_iteration(MirrorBlockJob *s, - BlockErrorAction *p_action) +static void mirror_iteration_done(MirrorOp *op, int ret) { - BlockDriverState *source = s->common.bs; - BlockDriverState *target = s->target; - QEMUIOVector qiov; - int ret, nb_sectors; - int64_t end; - struct iovec iov; + MirrorBlockJob *s = op->s; + struct iovec *iov; + int64_t chunk_num; + int i, nb_chunks, sectors_per_chunk; + + trace_mirror_iteration_done(s, op->sector_num, op->nb_sectors, ret); + + s->in_flight--; + iov = op->qiov.iov; + for (i = 0; i < op->qiov.niov; i++) { + MirrorBuffer *buf = (MirrorBuffer *) iov[i].iov_base; + QSIMPLEQ_INSERT_TAIL(&s->buf_free, buf, next); + s->buf_free_count++; + } - 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); + sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; + chunk_num = op->sector_num / sectors_per_chunk; + nb_chunks = op->nb_sectors / sectors_per_chunk; + bitmap_clear(s->in_flight_bitmap, chunk_num, nb_chunks); + if (s->cow_bitmap && ret >= 0) { + bitmap_set(s->cow_bitmap, chunk_num, nb_chunks); + } - /* Copy the dirty cluster. */ - iov.iov_base = s->buf; - iov.iov_len = nb_sectors * 512; - qemu_iovec_init_external(&qiov, &iov, 1); + g_slice_free(MirrorOp, op); + qemu_coroutine_enter(s->common.co, NULL); +} - trace_mirror_one_iteration(s, s->sector_num, nb_sectors); - ret = bdrv_co_readv(source, s->sector_num, nb_sectors, &qiov); +static void mirror_write_complete(void *opaque, int ret) +{ + MirrorOp *op = opaque; + MirrorBlockJob *s = op->s; if (ret < 0) { - *p_action = mirror_error_action(s, true, -ret); - goto fail; + BlockDriverState *source = s->common.bs; + BlockErrorAction action; + + bdrv_set_dirty(source, op->sector_num, op->nb_sectors); + action = mirror_error_action(s, false, -ret); + if (action == BDRV_ACTION_REPORT && s->ret >= 0) { + s->ret = ret; + } } - ret = bdrv_co_writev(target, s->sector_num, nb_sectors, &qiov); + mirror_iteration_done(op, ret); +} + +static void mirror_read_complete(void *opaque, int ret) +{ + MirrorOp *op = opaque; + MirrorBlockJob *s = op->s; if (ret < 0) { - *p_action = mirror_error_action(s, false, -ret); - s->synced = false; - goto fail; + BlockDriverState *source = s->common.bs; + BlockErrorAction action; + + bdrv_set_dirty(source, op->sector_num, op->nb_sectors); + action = mirror_error_action(s, true, -ret); + if (action == BDRV_ACTION_REPORT && s->ret >= 0) { + s->ret = ret; + } + + mirror_iteration_done(op, ret); + return; + } + bdrv_aio_writev(s->target, op->sector_num, &op->qiov, op->nb_sectors, + mirror_write_complete, op); +} + +static void coroutine_fn mirror_iteration(MirrorBlockJob *s) +{ + BlockDriverState *source = s->common.bs; + int nb_sectors, sectors_per_chunk, nb_chunks; + int64_t end, sector_num, next_chunk, next_sector, hbitmap_next_sector; + MirrorOp *op; + + s->sector_num = hbitmap_iter_next(&s->hbi); + if (s->sector_num < 0) { + bdrv_dirty_iter_init(source, &s->hbi); + s->sector_num = hbitmap_iter_next(&s->hbi); + trace_mirror_restart_iter(s, bdrv_get_dirty_count(source)); + assert(s->sector_num >= 0); + } + + hbitmap_next_sector = s->sector_num; + sector_num = s->sector_num; + sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; + end = s->common.len >> BDRV_SECTOR_BITS; + + /* Extend the QEMUIOVector to include all adjacent blocks that will + * be copied in this operation. + * + * We have to do this if we have no backing file yet in the destination, + * and the cluster size is very large. Then we need to do COW ourselves. + * The first time a cluster is copied, copy it entirely. Note that, + * because both the granularity and the cluster size are powers of two, + * the number of sectors to copy cannot exceed one cluster. + * + * We also want to extend the QEMUIOVector to include more adjacent + * dirty blocks if possible, to limit the number of I/O operations and + * run efficiently even with a small granularity. + */ + nb_chunks = 0; + nb_sectors = 0; + next_sector = sector_num; + next_chunk = sector_num / sectors_per_chunk; + + /* Wait for I/O to this cluster (from a previous iteration) to be done. */ + while (test_bit(next_chunk, s->in_flight_bitmap)) { + trace_mirror_yield_in_flight(s, sector_num, s->in_flight); + qemu_coroutine_yield(); + } + + do { + int added_sectors, added_chunks; + + if (!bdrv_get_dirty(source, next_sector) || + test_bit(next_chunk, s->in_flight_bitmap)) { + assert(nb_sectors > 0); + break; + } + + added_sectors = sectors_per_chunk; + if (s->cow_bitmap && !test_bit(next_chunk, s->cow_bitmap)) { + bdrv_round_to_clusters(s->target, + next_sector, added_sectors, + &next_sector, &added_sectors); + + /* On the first iteration, the rounding may make us copy + * sectors before the first dirty one. + */ + if (next_sector < sector_num) { + assert(nb_sectors == 0); + sector_num = next_sector; + next_chunk = next_sector / sectors_per_chunk; + } + } + + added_sectors = MIN(added_sectors, end - (sector_num + nb_sectors)); + added_chunks = (added_sectors + sectors_per_chunk - 1) / sectors_per_chunk; + + /* When doing COW, it may happen that there is not enough space for + * a full cluster. Wait if that is the case. + */ + while (nb_chunks == 0 && s->buf_free_count < added_chunks) { + trace_mirror_yield_buf_busy(s, nb_chunks, s->in_flight); + qemu_coroutine_yield(); + } + if (s->buf_free_count < nb_chunks + added_chunks) { + trace_mirror_break_buf_busy(s, nb_chunks, s->in_flight); + break; + } + + /* We have enough free space to copy these sectors. */ + bitmap_set(s->in_flight_bitmap, next_chunk, added_chunks); + + nb_sectors += added_sectors; + nb_chunks += added_chunks; + next_sector += added_sectors; + next_chunk += added_chunks; + } while (next_sector < end); + + /* Allocate a MirrorOp that is used as an AIO callback. */ + op = g_slice_new(MirrorOp); + op->s = s; + op->sector_num = sector_num; + op->nb_sectors = nb_sectors; + + /* Now make a QEMUIOVector taking enough granularity-sized chunks + * from s->buf_free. + */ + qemu_iovec_init(&op->qiov, nb_chunks); + next_sector = sector_num; + while (nb_chunks-- > 0) { + MirrorBuffer *buf = QSIMPLEQ_FIRST(&s->buf_free); + QSIMPLEQ_REMOVE_HEAD(&s->buf_free, next); + s->buf_free_count--; + qemu_iovec_add(&op->qiov, buf, s->granularity); + + /* Advance the HBitmapIter in parallel, so that we do not examine + * the same sector twice. + */ + if (next_sector > hbitmap_next_sector && bdrv_get_dirty(source, next_sector)) { + hbitmap_next_sector = hbitmap_iter_next(&s->hbi); + } + + next_sector += sectors_per_chunk; } - return 0; -fail: - /* Try again later. */ - bdrv_set_dirty(source, s->sector_num, nb_sectors); - return ret; + bdrv_reset_dirty(source, sector_num, nb_sectors); + + /* Copy the dirty cluster. */ + s->in_flight++; + trace_mirror_one_iteration(s, sector_num, nb_sectors); + bdrv_aio_readv(source, sector_num, &op->qiov, nb_sectors, + mirror_read_complete, op); +} + +static void mirror_free_init(MirrorBlockJob *s) +{ + int granularity = s->granularity; + size_t buf_size = s->buf_size; + uint8_t *buf = s->buf; + + assert(s->buf_free_count == 0); + QSIMPLEQ_INIT(&s->buf_free); + while (buf_size != 0) { + MirrorBuffer *cur = (MirrorBuffer *)buf; + QSIMPLEQ_INSERT_TAIL(&s->buf_free, cur, next); + s->buf_free_count++; + buf_size -= granularity; + buf += granularity; + } +} + +static void mirror_drain(MirrorBlockJob *s) +{ + while (s->in_flight > 0) { + qemu_coroutine_yield(); + } } static void coroutine_fn mirror_run(void *opaque) { MirrorBlockJob *s = opaque; BlockDriverState *bs = s->common.bs; - int64_t sector_num, end; + int64_t sector_num, end, sectors_per_chunk, length; + uint64_t last_pause_ns; + BlockDriverInfo bdi; + char backing_filename[1024]; int ret = 0; int n; @@ -105,20 +305,39 @@ static void coroutine_fn mirror_run(void *opaque) } s->common.len = bdrv_getlength(bs); - if (s->common.len < 0) { + if (s->common.len <= 0) { block_job_completed(&s->common, s->common.len); return; } + length = (bdrv_getlength(bs) + s->granularity - 1) / s->granularity; + s->in_flight_bitmap = bitmap_new(length); + + /* If we have no backing file yet in the destination, we cannot let + * the destination do COW. Instead, we copy sectors around the + * dirty data if needed. We need a bitmap to do that. + */ + bdrv_get_backing_filename(s->target, backing_filename, + sizeof(backing_filename)); + if (backing_filename[0] && !s->target->backing_hd) { + bdrv_get_info(s->target, &bdi); + if (s->granularity < bdi.cluster_size) { + s->buf_size = MAX(s->buf_size, bdi.cluster_size); + s->cow_bitmap = bitmap_new(length); + } + } + end = s->common.len >> BDRV_SECTOR_BITS; - s->buf = qemu_blockalign(bs, BLOCK_SIZE); + s->buf = qemu_blockalign(bs, s->buf_size); + sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; + mirror_free_init(s); 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; + int64_t next = (sector_num | (sectors_per_chunk - 1)) + 1; ret = bdrv_co_is_allocated_above(bs, base, sector_num, next - sector_num, &n); @@ -136,24 +355,40 @@ static void coroutine_fn mirror_run(void *opaque) } } - s->sector_num = -1; + bdrv_dirty_iter_init(bs, &s->hbi); + last_pause_ns = qemu_get_clock_ns(rt_clock); for (;;) { uint64_t delay_ns; int64_t cnt; bool should_complete; + if (s->ret < 0) { + ret = s->ret; + goto immediate_exit; + } + cnt = bdrv_get_dirty_count(bs); - if (cnt != 0) { - BlockErrorAction action = BDRV_ACTION_REPORT; - ret = mirror_iteration(s, &action); - if (ret < 0 && action == BDRV_ACTION_REPORT) { - goto immediate_exit; + + /* Note that even when no rate limit is applied we need to yield + * periodically with no pending I/O so that qemu_aio_flush() returns. + * We do so every SLICE_TIME nanoseconds, or when there is an error, + * or when the source is clean, whichever comes first. + */ + if (qemu_get_clock_ns(rt_clock) - last_pause_ns < SLICE_TIME && + s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { + if (s->in_flight == MAX_IN_FLIGHT || s->buf_free_count == 0 || + (cnt == 0 && s->in_flight > 0)) { + trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt); + qemu_coroutine_yield(); + continue; + } else if (cnt != 0) { + mirror_iteration(s); + continue; } - cnt = bdrv_get_dirty_count(bs); } should_complete = false; - if (cnt == 0) { + if (s->in_flight == 0 && cnt == 0) { trace_mirror_before_flush(s); ret = bdrv_flush(s->target); if (ret < 0) { @@ -196,23 +431,20 @@ static void coroutine_fn mirror_run(void *opaque) trace_mirror_before_sleep(s, cnt, s->synced); if (!s->synced) { /* Publish progress */ - s->common.offset = end * BDRV_SECTOR_SIZE - cnt * BLOCK_SIZE; + s->common.offset = (end - cnt) * BDRV_SECTOR_SIZE; if (s->common.speed) { - delay_ns = ratelimit_calculate_delay(&s->limit, BDRV_SECTORS_PER_DIRTY_CHUNK); + delay_ns = ratelimit_calculate_delay(&s->limit, sectors_per_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 bdrv_drain_all() 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); + delay_ns = (s->in_flight == 0 && 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 @@ -222,11 +454,24 @@ static void coroutine_fn mirror_run(void *opaque) s->common.cancelled = false; break; } + last_pause_ns = qemu_get_clock_ns(rt_clock); } immediate_exit: + if (s->in_flight > 0) { + /* We get here only if something went wrong. Either the job failed, + * or it was cancelled prematurely so that we do not guarantee that + * the target is a copy of the source. + */ + assert(ret < 0 || (!s->synced && block_job_is_cancelled(&s->common))); + mirror_drain(s); + } + + assert(s->in_flight == 0); qemu_vfree(s->buf); - bdrv_set_dirty_tracking(bs, false); + g_free(s->cow_bitmap); + g_free(s->in_flight_bitmap); + bdrv_set_dirty_tracking(bs, 0); bdrv_iostatus_disable(s->target); if (s->should_complete && ret == 0) { if (bdrv_get_flags(s->target) != bdrv_get_flags(s->common.bs)) { @@ -288,14 +533,28 @@ static BlockJobType mirror_job_type = { }; void mirror_start(BlockDriverState *bs, BlockDriverState *target, - int64_t speed, MirrorSyncMode mode, - BlockdevOnError on_source_error, + int64_t speed, int64_t granularity, int64_t buf_size, + MirrorSyncMode mode, BlockdevOnError on_source_error, BlockdevOnError on_target_error, BlockDriverCompletionFunc *cb, void *opaque, Error **errp) { MirrorBlockJob *s; + if (granularity == 0) { + /* Choose the default granularity based on the target file's cluster + * size, clamped between 4k and 64k. */ + BlockDriverInfo bdi; + if (bdrv_get_info(target, &bdi) >= 0 && bdi.cluster_size != 0) { + granularity = MAX(4096, bdi.cluster_size); + granularity = MIN(65536, granularity); + } else { + granularity = 65536; + } + } + + assert ((granularity & (granularity - 1)) == 0); + if ((on_source_error == BLOCKDEV_ON_ERROR_STOP || on_source_error == BLOCKDEV_ON_ERROR_ENOSPC) && !bdrv_iostatus_is_enabled(bs)) { @@ -312,7 +571,10 @@ void mirror_start(BlockDriverState *bs, BlockDriverState *target, s->on_target_error = on_target_error; s->target = target; s->mode = mode; - bdrv_set_dirty_tracking(bs, true); + s->granularity = granularity; + s->buf_size = MAX(buf_size, granularity); + + bdrv_set_dirty_tracking(bs, granularity); bdrv_set_enable_write_cache(s->target, true); bdrv_set_on_error(s->target, on_target_error, on_target_error); bdrv_iostatus_enable(s->target); |