[PATCH 3/3] btrfs: Remove BUG_ON() when failed searching block_group_cache in unpin_extent_range()

[Zhaolei <zhaolei@cn.fujitsu.com>]

From: Zhao Lei <zhaolei@cn.fujitsu.com>

Above BUG_ON() was triggered only one time in my test, but hadn't
happened again in same env.

The reason maybe:
A block group which include pinned space was removed before
unpin_extent_range(), and no other block_group_cache after
"start" pos, so the code entered into above BUG_ON().

To support auto-remove-bgs, we can remove above BUG_ON(), and bypass
removed bgs.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
---
 fs/btrfs/extent-tree.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 8b51eb5..ef0b40d 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5751,7 +5751,8 @@ static int unpin_extent_range(struct btrfs_root *root, u64 start, u64 end,
 			if (cache)
 				btrfs_put_block_group(cache);
 			cache = btrfs_lookup_block_group(fs_info, start);
-			BUG_ON(!cache); /* Logic error */
+			if (!cache)
+				break;
 		}
 
 		len = cache->key.objectid + cache->key.offset - start;
-- 
1.8.5.1