After it is done with updating refcounts in the cache, update_refcount writes
all changed entries to disk. If a refcount block allocation fails, however,
there was no change yet and therefore first_index = last_index = -1. Don't
treat -1 as a normal sector index (resulting in a 512 byte write!) but return
without updating anything in this case.
Signed-off-by: Kevin Wolf <kw...@redhat.com>
---
block/qcow2-refcount.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 5b7cda4..22b0b45 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -417,6 +417,10 @@ static int write_refcount_block_entries(BlockDriverState
*bs,
return 0;
}
+ if (first_index < 0) {
+ return 0;
+ }
+
first_index &= ~(REFCOUNTS_PER_SECTOR - 1);
last_index = (last_index + REFCOUNTS_PER_SECTOR)
& ~(REFCOUNTS_PER_SECTOR - 1);
--
1.6.6.1
