1 files changed, 36 insertions, 11 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 4a4f2d810d9f..a6969538bca2 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -365,8 +365,9 @@ error:
  *
  * returns 0 if everything worked, non-zero otherwise.
  */
-int alloc_extent(struct btrfs_root *root, u64 num_blocks, u64 search_start,
-                         u64 search_end, u64 owner, struct btrfs_key *ins)
+static int alloc_extent(struct btrfs_root *root, u64 num_blocks,
+                        u64 search_start, u64 search_end, u64 owner,
+                        struct btrfs_key *ins)
 {
         int ret;
         int pending_ret;
@@ -425,7 +426,12 @@ struct btrfs_buffer *btrfs_alloc_free_block(struct btrfs_root *root)
         return buf;
 }
 
-int walk_down_tree(struct btrfs_root *root, struct btrfs_path *path, int *level)
+/*
+ * helper function for drop_snapshot, this walks down the tree dropping ref
+ * counts as it goes.
+ */
+static int walk_down_tree(struct btrfs_root *root,
+                          struct btrfs_path *path, int *level)
 {
         struct btrfs_buffer *next;
         struct btrfs_buffer *cur;
@@ -437,6 +443,9 @@ int walk_down_tree(struct btrfs_root *root, struct btrfs_path *path, int *level)
         BUG_ON(ret);
         if (refs > 1)
                 goto out;
+        /*
+         * walk down to the last node level and free all the leaves
+         */
         while(*level > 0) {
                 cur = path->nodes[*level];
                 if (path->slots[*level] >=
@@ -467,7 +476,13 @@ out:
         return 0;
 }
 
-int walk_up_tree(struct btrfs_root *root, struct btrfs_path *path, int *level)
+/*
+ * helper for dropping snapshots.  This walks back up the tree in the path
+ * to find the first node higher up where we haven't yet gone through
+ * all the slots
+ */
+static int walk_up_tree(struct btrfs_root *root, struct btrfs_path *path,
+                        int *level)
 {
         int i;
         int slot;
@@ -491,9 +506,15 @@ int walk_up_tree(struct btrfs_root *root, struct btrfs_path *path, int *level)
         return 1;
 }
 
+/*
+ * drop the reference count on the tree rooted at 'snap'.  This traverses
+ * the tree freeing any blocks that have a ref count of zero after being
+ * decremented.
+ */
 int btrfs_drop_snapshot(struct btrfs_root *root, struct btrfs_buffer *snap)
 {
-        int ret;
+        int ret = 0;;
+        int wret;
         int level;
         struct btrfs_path path;
         int i;
@@ -506,18 +527,22 @@ int btrfs_drop_snapshot(struct btrfs_root *root, struct btrfs_buffer *snap)
         path.nodes[level] = snap;
         path.slots[level] = 0;
         while(1) {
-                ret = walk_down_tree(root, &path, &level);
-                if (ret > 0)
+                wret = walk_down_tree(root, &path, &level);
+                if (wret > 0)
                         break;
-                ret = walk_up_tree(root, &path, &level);
-                if (ret > 0)
+                if (wret < 0)
+                        ret = wret;
+
+                wret = walk_up_tree(root, &path, &level);
+                if (wret > 0)
                         break;
+                if (wret < 0)
+                        ret = wret;
         }
         for (i = 0; i <= orig_level; i++) {
                 if (path.nodes[i]) {
                         btrfs_block_release(root, path.nodes[i]);
                 }
         }
-
-        return 0;
+        return ret;
 }