1 files changed, 58 insertions, 14 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index aabbb3f53683..e8755c21f4b9 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -1656,16 +1656,60 @@ static int ext4_ext_try_to_merge_right(struct inode *inode,
 }
 
 /*
+ * This function does a very simple check to see if we can collapse
+ * an extent tree with a single extent tree leaf block into the inode.
+ */
+static void ext4_ext_try_to_merge_up(handle_t *handle,
+                                     struct inode *inode,
+                                     struct ext4_ext_path *path)
+{
+        size_t s;
+        unsigned max_root = ext4_ext_space_root(inode, 0);
+        ext4_fsblk_t blk;
+
+        if ((path[0].p_depth != 1) ||
+            (le16_to_cpu(path[0].p_hdr->eh_entries) != 1) ||
+            (le16_to_cpu(path[1].p_hdr->eh_entries) > max_root))
+                return;
+
+        /*
+         * We need to modify the block allocation bitmap and the block
+         * group descriptor to release the extent tree block.  If we
+         * can't get the journal credits, give up.
+         */
+        if (ext4_journal_extend(handle, 2))
+                return;
+
+        /*
+         * Copy the extent data up to the inode
+         */
+        blk = ext4_idx_pblock(path[0].p_idx);
+        s = le16_to_cpu(path[1].p_hdr->eh_entries) *
+                sizeof(struct ext4_extent_idx);
+        s += sizeof(struct ext4_extent_header);
+
+        memcpy(path[0].p_hdr, path[1].p_hdr, s);
+        path[0].p_depth = 0;
+        path[0].p_ext = EXT_FIRST_EXTENT(path[0].p_hdr) +
+                (path[1].p_ext - EXT_FIRST_EXTENT(path[1].p_hdr));
+        path[0].p_hdr->eh_max = cpu_to_le16(max_root);
+
+        brelse(path[1].p_bh);
+        ext4_free_blocks(handle, inode, NULL, blk, 1,
+                         EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
+}
+
+/*
  * This function tries to merge the @ex extent to neighbours in the tree.
  * return 1 if merge left else 0.
  */
-static int ext4_ext_try_to_merge(struct inode *inode,
+static void ext4_ext_try_to_merge(handle_t *handle,
+                                  struct inode *inode,
                                   struct ext4_ext_path *path,
                                   struct ext4_extent *ex) {
         struct ext4_extent_header *eh;
         unsigned int depth;
         int merge_done = 0;
-        int ret = 0;
 
         depth = ext_depth(inode);
         BUG_ON(path[depth].p_hdr == NULL);
@@ -1675,9 +1719,9 @@ static int ext4_ext_try_to_merge(struct inode *inode,
                 merge_done = ext4_ext_try_to_merge_right(inode, path, ex - 1);
 
         if (!merge_done)
-                ret = ext4_ext_try_to_merge_right(inode, path, ex);
+                (void) ext4_ext_try_to_merge_right(inode, path, ex);
 
-        return ret;
+        ext4_ext_try_to_merge_up(handle, inode, path);
 }
 
 /*
@@ -1893,7 +1937,7 @@ has_space:
 merge:
         /* try to merge extents */
         if (!(flag & EXT4_GET_BLOCKS_PRE_IO))
-                ext4_ext_try_to_merge(inode, path, nearex);
+                ext4_ext_try_to_merge(handle, inode, path, nearex);
 
 
         /* time to correct all indexes above */
@@ -1901,7 +1945,7 @@ merge:
         if (err)
                 goto cleanup;
 
-        err = ext4_ext_dirty(handle, inode, path + depth);
+        err = ext4_ext_dirty(handle, inode, path + path->p_depth);
 
 cleanup:
         if (npath) {
@@ -2924,9 +2968,9 @@ static int ext4_split_extent_at(handle_t *handle,
                         ext4_ext_mark_initialized(ex);
 
                 if (!(flags & EXT4_GET_BLOCKS_PRE_IO))
-                        ext4_ext_try_to_merge(inode, path, ex);
+                        ext4_ext_try_to_merge(handle, inode, path, ex);
 
-                err = ext4_ext_dirty(handle, inode, path + depth);
+                err = ext4_ext_dirty(handle, inode, path + path->p_depth);
                 goto out;
         }
 
@@ -2958,8 +3002,8 @@ static int ext4_split_extent_at(handle_t *handle,
                         goto fix_extent_len;
                 /* update the extent length and mark as initialized */
                 ex->ee_len = cpu_to_le16(ee_len);
-                ext4_ext_try_to_merge(inode, path, ex);
-                err = ext4_ext_dirty(handle, inode, path + depth);
+                ext4_ext_try_to_merge(handle, inode, path, ex);
+                err = ext4_ext_dirty(handle, inode, path + path->p_depth);
                 goto out;
         } else if (err)
                 goto fix_extent_len;
@@ -3191,8 +3235,8 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
                 if (err)
                         goto out;
                 ext4_ext_mark_initialized(ex);
-                ext4_ext_try_to_merge(inode, path, ex);
-                err = ext4_ext_dirty(handle, inode, path + depth);
+                ext4_ext_try_to_merge(handle, inode, path, ex);
+                err = ext4_ext_dirty(handle, inode, path + path->p_depth);
                 goto out;
         }
 
@@ -3333,10 +3377,10 @@ static int ext4_convert_unwritten_extents_endio(handle_t *handle,
         /* note: ext4_ext_correct_indexes() isn't needed here because
          * borders are not changed
          */
-        ext4_ext_try_to_merge(inode, path, ex);
+        ext4_ext_try_to_merge(handle, inode, path, ex);
 
         /* Mark modified extent as dirty */
-        err = ext4_ext_dirty(handle, inode, path + depth);
+        err = ext4_ext_dirty(handle, inode, path + path->p_depth);
 out:
         ext4_ext_show_leaf(inode, path);
         return err;