From 9f8e668eb1826434f61a63ff260d6c8b466e483a Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Fri, 17 Sep 2010 17:02:09 +0200 Subject: [PATCH] qcow2: Get rid of additional sync on COW We always have a sync for the refcount update when a new cluster is allocated. If we move this past the COW, we can save an additional sync. Signed-off-by: Kevin Wolf --- block/qcow2-cluster.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 818c0dbd44..cb2e33f1ac 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -415,7 +415,7 @@ static int copy_sectors(BlockDriverState *bs, uint64_t start_sect, &s->aes_encrypt_key); } BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE); - ret = bdrv_write_sync(bs->file, (cluster_offset >> 9) + n_start, + ret = bdrv_write(bs->file, (cluster_offset >> 9) + n_start, s->cluster_data, n); if (ret < 0) return ret; @@ -714,6 +714,13 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m) (i << s->cluster_bits)) | QCOW_OFLAG_COPIED); } + /* + * Before we update the L2 table to actually point to the new cluster, we + * need to be sure that the refcounts have been increased and COW was + * handled. + */ + bdrv_flush(bs->file); + ret = write_l2_entries(bs, l2_table, l2_offset, l2_index, m->nb_clusters); if (ret < 0) { qcow2_l2_cache_reset(bs); @@ -865,7 +872,6 @@ int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset, QLIST_REMOVE(m, next_in_flight); return cluster_offset; } - bdrv_flush(bs->file); /* save info needed for meta data update */ m->offset = offset; -- 2.11.4.GIT