From: John Snow <js...@redhat.com> Teach mirror two new tricks for using bitmaps:
Always: no matter what, we synchronize the copy_bitmap back to the sync_bitmap. In effect, this allows us resume a failed mirror at a later date, since the target bdrv should be exactly in the state referenced by the bitmap. Conditional: On success only, we sync the bitmap. This is akin to incremental backup modes; we can use this bitmap to later refresh a successfully created mirror, or possibly re-try the whole failed mirror if we are able to rollback the target to the state before starting the mirror. Based on original work by John Snow. Signed-off-by: Fabian Grünbichler <f.gruenbich...@proxmox.com> --- block/mirror.c | 28 ++++++++++++++++++++-------- blockdev.c | 3 +++ 2 files changed, 23 insertions(+), 8 deletions(-) diff --git a/block/mirror.c b/block/mirror.c index d64c8203ef..bc4f4563d9 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -654,8 +654,6 @@ static int mirror_exit_common(Job *job) bdrv_unfreeze_backing_chain(mirror_top_bs, target_bs); } - bdrv_release_dirty_bitmap(s->dirty_bitmap); - /* Make sure that the source BDS doesn't go away during bdrv_replace_node, * before we can call bdrv_drained_end */ bdrv_ref(src); @@ -755,6 +753,18 @@ static int mirror_exit_common(Job *job) blk_set_perm(bjob->blk, 0, BLK_PERM_ALL, &error_abort); blk_insert_bs(bjob->blk, mirror_top_bs, &error_abort); + if (s->sync_bitmap) { + if (s->bitmap_mode == BITMAP_SYNC_MODE_ALWAYS || + (s->bitmap_mode == BITMAP_SYNC_MODE_ON_SUCCESS && + job->ret == 0 && ret == 0)) { + /* Success; synchronize copy back to sync. */ + bdrv_clear_dirty_bitmap(s->sync_bitmap, NULL); + bdrv_dirty_bitmap_merge_internal(s->sync_bitmap, s->dirty_bitmap, + NULL, true); + } + } + bdrv_release_dirty_bitmap(s->dirty_bitmap); + bs_opaque->job = NULL; bdrv_drained_end(src); @@ -1592,10 +1602,6 @@ static BlockJob *mirror_start_job( " sync mode", MirrorSyncMode_str(sync_mode)); return NULL; - } else if (bitmap_mode != BITMAP_SYNC_MODE_NEVER) { - error_setg(errp, - "Bitmap Sync Mode '%s' is not supported by Mirror", - BitmapSyncMode_str(bitmap_mode)); } } else if (bitmap) { error_setg(errp, @@ -1612,6 +1618,12 @@ static BlockJob *mirror_start_job( return NULL; } granularity = bdrv_dirty_bitmap_granularity(bitmap); + + if (bitmap_mode != BITMAP_SYNC_MODE_NEVER) { + if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_DEFAULT, errp)) { + return NULL; + } + } } else if (granularity == 0) { granularity = bdrv_get_default_bitmap_granularity(target); } @@ -1781,8 +1793,8 @@ static BlockJob *mirror_start_job( } if (s->sync_mode == MIRROR_SYNC_MODE_BITMAP) { - bdrv_merge_dirty_bitmap(s->dirty_bitmap, s->sync_bitmap, - NULL, &local_err); + bdrv_dirty_bitmap_merge_internal(s->dirty_bitmap, s->sync_bitmap, + NULL, true); if (local_err) { goto fail; } diff --git a/blockdev.c b/blockdev.c index 6baa1a33f5..0fd30a392d 100644 --- a/blockdev.c +++ b/blockdev.c @@ -3019,6 +3019,9 @@ static void blockdev_mirror_common(const char *job_id, BlockDriverState *bs, if (bdrv_dirty_bitmap_check(bitmap, BDRV_BITMAP_ALLOW_RO, errp)) { return; } + } else if (has_bitmap_mode) { + error_setg(errp, "Cannot specify bitmap sync mode without a bitmap"); + return; } if (!has_replaces) { -- 2.20.1