[PATCH v4 26/30] qcow2: Restrict qcow2_co_pwrite_zeroes() to full clusters only

[Alberto Garcia]

Ideally it should be possible to zero individual subclusters using
this function, but this is currently not implemented.

Signed-off-by: Alberto Garcia <be...@igalia.com>
Reviewed-by: Max Reitz <mre...@redhat.com>
---
 block/qcow2.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/block/qcow2.c b/block/qcow2.c
index ad230ed1b1..d406ef355b 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -3743,7 +3743,9 @@ static coroutine_fn int 
qcow2_co_pwrite_zeroes(BlockDriverState *bs,
         bytes = s->cluster_size;
         nr = s->cluster_size;
         ret = qcow2_get_host_offset(bs, offset, &nr, &off, &type);
-        if (ret < 0 ||
+        /* TODO: allow zeroing separate subclusters, we only allow
+         * zeroing full clusters at the moment. */
+        if (ret < 0 || nr != bytes ||
             (type != QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN &&
              type != QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC &&
              type != QCOW2_SUBCLUSTER_ZERO_PLAIN &&
-- 
2.20.1