ext4: get rid of ppath in ext4_ext_create_new_leaf()

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 ext4_ext_create_new_leaf(), the following is
done here:

 * Free the extents path when an error is encountered.
 * Its caller needs to update ppath if it uses ppath.

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/20240822023545.1994557-14-libaokun@huaweicloud.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/extents.c

@@ -1397,13 +1397,12 @@ static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
  * finds empty index and adds new leaf.
  * if no free index is found, then it requests in-depth growing.
  */
-static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
-				    unsigned int mb_flags,
-				    unsigned int gb_flags,
-				    struct ext4_ext_path **ppath,
-				    struct ext4_extent *newext)
+static struct ext4_ext_path *
+ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
+			 unsigned int mb_flags, unsigned int gb_flags,
+			 struct ext4_ext_path *path,
+			 struct ext4_extent *newext)
 {
-	struct ext4_ext_path *path = *ppath;
 	struct ext4_ext_path *curp;
 	int depth, i, err = 0;
 
@@ -1424,28 +1423,25 @@ static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
 		 * entry: create all needed subtree and add new leaf */
 		err = ext4_ext_split(handle, inode, mb_flags, path, newext, i);
 		if (err)
-			goto out;
+			goto errout;
 
 		/* refill path */
 		path = ext4_find_extent(inode,
 				    (ext4_lblk_t)le32_to_cpu(newext->ee_block),
 				    path, gb_flags);
-		if (IS_ERR(path))
-			err = PTR_ERR(path);
+		return path;
 	} else {
 		/* tree is full, time to grow in depth */
 		err = ext4_ext_grow_indepth(handle, inode, mb_flags);
 		if (err)
-			goto out;
+			goto errout;
 
 		/* refill path */
 		path = ext4_find_extent(inode,
 				   (ext4_lblk_t)le32_to_cpu(newext->ee_block),
 				    path, gb_flags);
-		if (IS_ERR(path)) {
-			err = PTR_ERR(path);
-			goto out;
-		}
+		if (IS_ERR(path))
+			return path;
 
 		/*
 		 * only first (depth 0 -> 1) produces free space;
@@ -1457,9 +1453,11 @@ static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
 			goto repeat;
 		}
 	}
-out:
-	*ppath = IS_ERR(path) ? NULL : path;
-	return err;
+	return path;
+
+errout:
+	ext4_free_ext_path(path);
+	return ERR_PTR(err);
 }
 
 /*
@@ -2112,11 +2110,14 @@ int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
 	 */
 	if (gb_flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
 		mb_flags |= EXT4_MB_USE_RESERVED;
-	err = ext4_ext_create_new_leaf(handle, inode, mb_flags, gb_flags,
-				       ppath, newext);
-	if (err)
+	path = ext4_ext_create_new_leaf(handle, inode, mb_flags, gb_flags,
+					path, newext);
+	if (IS_ERR(path)) {
+		*ppath = NULL;
+		err = PTR_ERR(path);
 		goto cleanup;
-	path = *ppath;
+	}
+	*ppath = path;
 	depth = ext_depth(inode);
 	eh = path[depth].p_hdr;