ext4: call ext4_ext_drop_refs() from ext4_ext_find_extent()

In nearly all of the calls to ext4_ext_find_extent() where the caller
is trying to recycle the path object, ext4_ext_drop_refs() gets called
to release the buffer heads before the path object gets overwritten.
To simplify things for the callers, and to avoid the possibility of a
memory leak, make ext4_ext_find_extent() responsible for dropping the
buffers.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index ccdd2af..4f4d523 100644 (file)
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -867,8 +867,10 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
        eh = ext_inode_hdr(inode);
        depth = ext_depth(inode);
 
-       /* account possible depth increase */
-       if (!path) {
+       if (path)
+               ext4_ext_drop_refs(path);
+       else {
+               /* account possible depth increase */
                path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
                                GFP_NOFS);
                if (unlikely(!path))
@@ -1356,7 +1358,6 @@ repeat:
                        goto out;
 
                /* refill path */
-               ext4_ext_drop_refs(path);
                path = ext4_ext_find_extent(inode,
                                    (ext4_lblk_t)le32_to_cpu(newext->ee_block),
                                    ppath, gb_flags);
@@ -1369,7 +1370,6 @@ repeat:
                        goto out;
 
                /* refill path */
-               ext4_ext_drop_refs(path);
                path = ext4_ext_find_extent(inode,
                                   (ext4_lblk_t)le32_to_cpu(newext->ee_block),
                                    ppath, gb_flags);
@@ -3319,7 +3319,6 @@ static int ext4_split_extent(handle_t *handle,
         * Update path is required because previous ext4_split_extent_at() may
         * result in split of original leaf or extent zeroout.
         */
-       ext4_ext_drop_refs(path);
        path = ext4_ext_find_extent(inode, map->m_lblk, ppath, 0);
        if (IS_ERR(path))
                return PTR_ERR(path);
@@ -3718,7 +3717,6 @@ static int ext4_convert_unwritten_extents_endio(handle_t *handle,
                                                 EXT4_GET_BLOCKS_CONVERT);
                if (err < 0)
                        return err;
-               ext4_ext_drop_refs(path);
                path = ext4_ext_find_extent(inode, map->m_lblk, ppath, 0);
                if (IS_ERR(path))
                        return PTR_ERR(path);
@@ -3947,7 +3945,6 @@ convert_initialized_extent(handle_t *handle, struct inode *inode,
                                EXT4_GET_BLOCKS_CONVERT_UNWRITTEN);
                if (err < 0)
                        return err;
-               ext4_ext_drop_refs(path);
                path = ext4_ext_find_extent(inode, map->m_lblk, ppath, 0);
                if (IS_ERR(path))
                        return PTR_ERR(path);