[Qemu-devel] [PATCH] qcow2: preserve free_byte_offset when qcow2_alloc_bytes() fails

[Stefan Hajnoczi]

When qcow2_alloc_clusters() error handling code was introduced in commit
5d757b563d59142ca81e1073a8e8396750a0ad1a, the value of free_byte_offset
was clobbered in the error case.  This patch keeps free_byte_offset at 0
so we will try to allocate clusters again next time this function is
called.

Signed-off-by: Stefan Hajnoczi <address@hidden>
---
 block/qcow2-refcount.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 812c93c..2d5420c 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -627,10 +627,11 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
     BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_BYTES);
     assert(size > 0 && size <= s->cluster_size);
     if (s->free_byte_offset == 0) {
-        s->free_byte_offset = qcow2_alloc_clusters(bs, s->cluster_size);
-        if (s->free_byte_offset < 0) {
-            return s->free_byte_offset;
+        offset = qcow2_alloc_clusters(bs, s->cluster_size);
+        if (offset < 0) {
+            return offset;
         }
+        s->free_byte_offset = offset;
     }
  redo:
     free_in_cluster = s->cluster_size -
-- 
1.7.10