btrfs_drop_extents: make sure the item is getting smaller before truncate

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 3c00f967eccb..55abdf997ca5 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -45,6 +45,9 @@ static int cache_block_group(struct btrfs_root *root,
         u64 first_free;
         int found = 0;
 
+        if (!block_group)
+                return 0;
+
         root = root->fs_info->extent_root;
         free_space_cache = &root->fs_info->free_space_cache;
 
@@ -168,6 +171,11 @@ static u64 find_search_start(struct btrfs_root *root,
         u64 cache_miss = 0;
         int wrapped = 0;
 
+        if (!cache) {
+                cache = btrfs_lookup_block_group(root->fs_info, search_start);
+                if (!cache)
+                        return search_start;
+        }
 again:
         ret = cache_block_group(root, cache);
         if (ret)