ext4: Fix memory and buffer head leak in callers to ext4_ext_find_extent()

The path variable returned via ext4_ext_find_extent is a kmalloc
variable and needs to be freeded.  It also contains a reference to
buffer_head which needs to be dropped.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMingming Cao <cmm@us.ibm.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/extents.c

@@ -349,7 +349,7 @@ static void ext4_ext_show_leaf(struct inode *inode, struct ext4_ext_path *path)
 #define ext4_ext_show_leaf(inode,path)
 #endif
 
-static void ext4_ext_drop_refs(struct ext4_ext_path *path)
+void ext4_ext_drop_refs(struct ext4_ext_path *path)
 {
 	int depth = path->p_depth;
 	int i;
@@ -2200,10 +2200,10 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
 		newdepth = ext_depth(inode);
 		if (newdepth != depth) {
 			depth = newdepth;
-			path = ext4_ext_find_extent(inode, iblock, NULL);
+			ext4_ext_drop_refs(path);
+			path = ext4_ext_find_extent(inode, iblock, path);
 			if (IS_ERR(path)) {
 				err = PTR_ERR(path);
-				path = NULL;
 				goto out;
 			}
 			eh = path[depth].p_hdr;

fs/ext4/migrate.c

@@ -43,6 +43,7 @@ static int finish_range(handle_t *handle, struct inode *inode,
 
 	if (IS_ERR(path)) {
 		retval = PTR_ERR(path);
+		path = NULL;
 		goto err_out;
 	}
 
@@ -74,6 +75,10 @@ static int finish_range(handle_t *handle, struct inode *inode,
 	}
 	retval = ext4_ext_insert_extent(handle, inode, path, &newext);
 err_out:
+	if (path) {
+		ext4_ext_drop_refs(path);
+		kfree(path);
+	}
 	lb->first_pblock = 0;
 	return retval;
 }

include/linux/ext4_fs_extents.h

@@ -227,5 +227,6 @@ extern int ext4_ext_search_left(struct inode *, struct ext4_ext_path *,
 						ext4_lblk_t *, ext4_fsblk_t *);
 extern int ext4_ext_search_right(struct inode *, struct ext4_ext_path *,
 						ext4_lblk_t *, ext4_fsblk_t *);
+extern void ext4_ext_drop_refs(struct ext4_ext_path *);
 #endif /* _LINUX_EXT4_EXTENTS */