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authorMax Reitz <mreitz@redhat.com>2015-09-11 18:47:51 +0200
committerKevin Wolf <kwolf@redhat.com>2015-09-14 16:51:37 +0200
commit2ac01520be8717f3492b10a083c3e0e22cb52cda (patch)
treecf39358b64bb3eb0d227db2b753d163f8012797a /block
parent3efffc3292d94271a15b1606b4a56adf6c6f04ed (diff)
qcow2: Make qcow2_alloc_bytes() more explicit
In case of -EAGAIN returned by update_refcount(), we should discard the cluster offset we were trying to allocate and request a new one, because in theory that old offset might now be taken by a refcount block. In practice, this was not the case due to update_refcount() generally returning strictly monotonic increasing cluster offsets. However, this behavior is not set in stone, and it is also not obvious when looking at qcow2_alloc_bytes() alone, so we should not rely on it. Reported-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block')
-rw-r--r--block/qcow2-refcount.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index a49d59e71e..2110839da4 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -949,11 +949,17 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
if (!offset || ROUND_UP(offset, s->cluster_size) != new_cluster) {
offset = new_cluster;
+ free_in_cluster = s->cluster_size;
+ } else {
+ free_in_cluster += s->cluster_size;
}
}
assert(offset);
ret = update_refcount(bs, offset, size, 1, false, QCOW2_DISCARD_NEVER);
+ if (ret < 0) {
+ offset = 0;
+ }
} while (ret == -EAGAIN);
if (ret < 0) {
return ret;