Btrfs: advance window_start if we're using a bitmap

If we span a long area in a bitmap we could end up taking a lot of time
searching to the next free area if we're searching from the original
window_start, so advance window_start in order to make sure we don't do any
superficial searching.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 61447a51f645..5802b1473c3d 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -2251,6 +2251,7 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group,
                                                  offset_index);
                                 continue;
                         }
+                        cluster->window_start += bytes;
                 } else {
                         ret = entry->offset;