ext4: get rid of ppath in convert_initialized_extent()

The use of path and ppath is now very confusing, so to make the code more
readable, pass path between functions uniformly, and get rid of ppath.

To get rid of the ppath in convert_initialized_extent(), the following is
done here:

 * Free the extents path when an error is encountered.

No functional changes.
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/20240822023545.1994557-23-libaokun@huaweicloud.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/extents.c

@@ -3811,13 +3811,12 @@ ext4_convert_unwritten_extents_endio(handle_t *handle, struct inode *inode,
 	return ERR_PTR(err);
 }
 
-static int
+static struct ext4_ext_path *
 convert_initialized_extent(handle_t *handle, struct inode *inode,
 			   struct ext4_map_blocks *map,
-			   struct ext4_ext_path **ppath,
+			   struct ext4_ext_path *path,
 			   unsigned int *allocated)
 {
-	struct ext4_ext_path *path = *ppath;
 	struct ext4_extent *ex;
 	ext4_lblk_t ee_block;
 	unsigned int ee_len;
@@ -3842,29 +3841,25 @@ convert_initialized_extent(handle_t *handle, struct inode *inode,
 	if (ee_block != map->m_lblk || ee_len > map->m_len) {
 		path = ext4_split_convert_extents(handle, inode, map, path,
 				EXT4_GET_BLOCKS_CONVERT_UNWRITTEN, NULL);
-		if (IS_ERR(path)) {
-			*ppath = NULL;
-			return PTR_ERR(path);
-		}
+		if (IS_ERR(path))
+			return path;
 
 		path = ext4_find_extent(inode, map->m_lblk, path, 0);
-		if (IS_ERR(path)) {
-			*ppath = NULL;
-			return PTR_ERR(path);
-		}
-		*ppath = path;
+		if (IS_ERR(path))
+			return path;
 		depth = ext_depth(inode);
 		ex = path[depth].p_ext;
 		if (!ex) {
 			EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
 					 (unsigned long) map->m_lblk);
-			return -EFSCORRUPTED;
+			err = -EFSCORRUPTED;
+			goto errout;
 		}
 	}
 
 	err = ext4_ext_get_access(handle, inode, path + depth);
 	if (err)
-		return err;
+		goto errout;
 	/* first mark the extent as unwritten */
 	ext4_ext_mark_unwritten(ex);
 
@@ -3876,7 +3871,7 @@ convert_initialized_extent(handle_t *handle, struct inode *inode,
 	/* Mark modified extent as dirty */
 	err = ext4_ext_dirty(handle, inode, path + path->p_depth);
 	if (err)
-		return err;
+		goto errout;
 	ext4_ext_show_leaf(inode, path);
 
 	ext4_update_inode_fsync_trans(handle, inode, 1);
@@ -3885,7 +3880,11 @@ convert_initialized_extent(handle_t *handle, struct inode *inode,
 	if (*allocated > map->m_len)
 		*allocated = map->m_len;
 	map->m_len = *allocated;
-	return 0;
+	return path;
+
+errout:
+	ext4_free_ext_path(path);
+	return ERR_PTR(err);
 }
 
 static struct ext4_ext_path *
@@ -4256,8 +4255,10 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 			 */
 			if ((!ext4_ext_is_unwritten(ex)) &&
 			    (flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN)) {
-				err = convert_initialized_extent(handle,
-					inode, map, &path, &allocated);
+				path = convert_initialized_extent(handle,
+					inode, map, path, &allocated);
+				if (IS_ERR(path))
+					err = PTR_ERR(path);
 				goto out;
 			} else if (!ext4_ext_is_unwritten(ex)) {
 				map->m_flags |= EXT4_MAP_MAPPED;