diff options
| author | Max Reitz <mreitz@redhat.com> | 2015-09-11 18:47:51 +0200 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2015-09-14 16:51:37 +0200 |
| commit | 2ac01520be8717f3492b10a083c3e0e22cb52cda (patch) | |
| tree | cf39358b64bb3eb0d227db2b753d163f8012797a | |
| parent | 3efffc3292d94271a15b1606b4a56adf6c6f04ed (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>
| -rw-r--r-- | block/qcow2-refcount.c | 6 |
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; |