block: avoid creating oversized writes in multiwrite_merge

Signed-off-by: Peter Lieven <[email protected]>
Reviewed-by: Ronnie Sahlberg <[email protected]>
Reviewed-by: Max Reitz <[email protected]>
Signed-off-by: Stefan Hajnoczi <[email protected]>

diff --git a/block.c b/block.c
index 76fcc1d6d36a754448d36e9f24c81cb17072d12b..41793419d8e1e8b3d429402af077988a02bec899 100644 (file)
--- a/block.c
+++ b/block.c
@@ -4446,6 +4446,11 @@ static int multiwrite_merge(BlockDriverState *bs, BlockRequest *reqs,
             merge = 0;
         }
 
+        if (bs->bl.max_transfer_length && reqs[outidx].nb_sectors +
+            reqs[i].nb_sectors > bs->bl.max_transfer_length) {
+            merge = 0;
+        }
+
         if (merge) {
             size_t size;
             QEMUIOVector *qiov = g_malloc0(sizeof(*qiov));