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qcow2: Remove unnecessary flush after L2 write

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When a new cluster was allocated, we only need a flush after the write to the
L2 table if it was a COW and we need to decrease the refcounts of the old
clusters.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2010-09-01 12:40:52 +02:00
parent ceb25e5c75
commit 7ec5e6a4ca
1 changed files with 12 additions and 4 deletions
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12
block/qcow2-cluster.c
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@ -655,7 +655,7 @@ static int write_l2_entries(BlockDriverState *bs, uint64_t *l2_table,
int ret;
BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE);
ret = bdrv_pwrite_sync(bs->file, l2_offset + start_offset,
ret = bdrv_pwrite(bs->file, l2_offset + start_offset,
&l2_table[l2_start_index], len);
if (ret < 0) {
return ret;
@ -718,9 +718,17 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
goto err;
}
for (i = 0; i < j; i++)
/*
* If this was a COW, we need to decrease the refcount of the old cluster.
* Also flush bs->file to get the right order for L2 and refcount update.
*/
if (j != 0) {
bdrv_flush(bs->file);
for (i = 0; i < j; i++) {
qcow2_free_any_clusters(bs,
be64_to_cpu(old_cluster[i]) & ~QCOW_OFLAG_COPIED, 1);
}
}
ret = 0;
err: