diff options
| author | Eric Blake <eblake@redhat.com> | 2016-11-17 14:13:55 -0600 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2016-11-22 15:59:22 +0100 |
| commit | ecdbead659f037dc572bba9eb1cd31a5a1a9ad9a (patch) | |
| tree | bee33b3293e97e6758588754336761f7ceba1b9f | |
| parent | a7764f1548ef9946af30a8f96be9cef10761f0c1 (diff) | |
qcow2: Inform block layer about discard boundaries
At the qcow2 layer, discard is only possible on a per-cluster
basis; at the moment, qcow2 silently rounds any unaligned
requests to this granularity. However, an upcoming patch will
fix a regression in the block layer ignoring too much of an
unaligned discard request, by changing the block layer to
break up a discard request at alignment boundaries; for that
to work, the block layer must know about our limits.
However, we can't go one step further by changing
qcow2_discard_clusters() to assert that requests are always
aligned, since that helper function is reached on paths
outside of the block layer.
CC: qemu-stable@nongnu.org
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
| -rw-r--r-- | block/qcow2.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/block/qcow2.c b/block/qcow2.c index 6d5689a23c..e22f6dc0c6 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1206,6 +1206,7 @@ static void qcow2_refresh_limits(BlockDriverState *bs, Error **errp) bs->bl.request_alignment = BDRV_SECTOR_SIZE; } bs->bl.pwrite_zeroes_alignment = s->cluster_size; + bs->bl.pdiscard_alignment = s->cluster_size; } static int qcow2_set_key(BlockDriverState *bs, const char *key) |