[PATCH] block/block-copy: fix s->copy_size for compressed cluster

[Vladimir Sementsov-Ogievskiy]

0e2402452f1f20429 allowed writes larger than cluster, but that's
unsupported for compressed write. Fix it.

Fixes: 0e2402452f1f20429
Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
 block/block-copy.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/block/block-copy.c b/block/block-copy.c
index c39cc9cffe..79798a1567 100644
--- a/block/block-copy.c
+++ b/block/block-copy.c
@@ -109,9 +109,9 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, 
BdrvChild *target,
         s->use_copy_range = false;
         s->copy_size = cluster_size;
     } else if (write_flags & BDRV_REQ_WRITE_COMPRESSED) {
-        /* Compression is not supported for copy_range */
+        /* Compression supports only cluster-size writes and no copy-range. */
         s->use_copy_range = false;
-        s->copy_size = MAX(cluster_size, BLOCK_COPY_MAX_BUFFER);
+        s->copy_size = cluster_size;
     } else {
         /*
          * copy_range does not respect max_transfer (it's a TODO), so we factor
-- 
2.21.0