ext4: get rid of ppath in ext4_split_convert_extents()

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_split_convert_extents(), the following is
done here:

 * 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/20240822023545.1994557-19-libaokun@huaweicloud.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/extents.c

@@ -3700,21 +3700,21 @@ static int ext4_ext_convert_to_initialized(handle_t *handle,
  * being filled will be convert to initialized by the end_io callback function
  * via ext4_convert_unwritten_extents().
  *
- * Returns the size of unwritten extent to be written on success.
+ * The size of unwritten extent to be written is passed to the caller via the
+ * allocated pointer. Return an extent path pointer on success, or an error
+ * pointer on failure.
  */
-static int ext4_split_convert_extents(handle_t *handle,
+static struct ext4_ext_path *ext4_split_convert_extents(handle_t *handle,
 					struct inode *inode,
 					struct ext4_map_blocks *map,
-					struct ext4_ext_path **ppath,
-					int flags)
+					struct ext4_ext_path *path,
+					int flags, unsigned int *allocated)
 {
-	struct ext4_ext_path *path = *ppath;
 	ext4_lblk_t eof_block;
 	ext4_lblk_t ee_block;
 	struct ext4_extent *ex;
 	unsigned int ee_len;
 	int split_flag = 0, depth;
-	unsigned int allocated = 0;
 
 	ext_debug(inode, "logical block %llu, max_blocks %u\n",
 		  (unsigned long long)map->m_lblk, map->m_len);
@@ -3742,14 +3742,8 @@ static int ext4_split_convert_extents(handle_t *handle,
 		split_flag |= (EXT4_EXT_MARK_UNWRIT2 | EXT4_EXT_DATA_VALID2);
 	}
 	flags |= EXT4_GET_BLOCKS_PRE_IO;
-	path = ext4_split_extent(handle, inode, path, map, split_flag, flags,
-				 &allocated);
-	if (IS_ERR(path)) {
-		*ppath = NULL;
-		return PTR_ERR(path);
-	}
-	*ppath = path;
-	return allocated;
+	return ext4_split_extent(handle, inode, path, map, split_flag, flags,
+				 allocated);
 }
 
 static int ext4_convert_unwritten_extents_endio(handle_t *handle,
@@ -3785,11 +3779,14 @@ static int ext4_convert_unwritten_extents_endio(handle_t *handle,
 			     inode->i_ino, (unsigned long long)ee_block, ee_len,
 			     (unsigned long long)map->m_lblk, map->m_len);
 #endif
-		err = ext4_split_convert_extents(handle, inode, map, ppath,
-						 EXT4_GET_BLOCKS_CONVERT);
-		if (err < 0)
-			return err;
-		path = ext4_find_extent(inode, map->m_lblk, *ppath, 0);
+		path = ext4_split_convert_extents(handle, inode, map, path,
+						EXT4_GET_BLOCKS_CONVERT, NULL);
+		if (IS_ERR(path)) {
+			*ppath = NULL;
+			return PTR_ERR(path);
+		}
+
+		path = ext4_find_extent(inode, map->m_lblk, path, 0);
 		if (IS_ERR(path)) {
 			*ppath = NULL;
 			return PTR_ERR(path);
@@ -3846,11 +3843,14 @@ convert_initialized_extent(handle_t *handle, struct inode *inode,
 		  (unsigned long long)ee_block, ee_len);
 
 	if (ee_block != map->m_lblk || ee_len > map->m_len) {
-		err = ext4_split_convert_extents(handle, inode, map, ppath,
-				EXT4_GET_BLOCKS_CONVERT_UNWRITTEN);
-		if (err < 0)
-			return err;
-		path = ext4_find_extent(inode, map->m_lblk, *ppath, 0);
+		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);
+		}
+
+		path = ext4_find_extent(inode, map->m_lblk, path, 0);
 		if (IS_ERR(path)) {
 			*ppath = NULL;
 			return PTR_ERR(path);
@@ -3916,19 +3916,20 @@ ext4_ext_handle_unwritten_extents(handle_t *handle, struct inode *inode,
 
 	/* get_block() before submitting IO, split the extent */
 	if (flags & EXT4_GET_BLOCKS_PRE_IO) {
-		ret = ext4_split_convert_extents(handle, inode, map, ppath,
-					 flags | EXT4_GET_BLOCKS_CONVERT);
-		if (ret < 0) {
-			err = ret;
+		*ppath = ext4_split_convert_extents(handle, inode, map, *ppath,
+				flags | EXT4_GET_BLOCKS_CONVERT, &allocated);
+		if (IS_ERR(*ppath)) {
+			err = PTR_ERR(*ppath);
+			*ppath = NULL;
 			goto out2;
 		}
 		/*
-		 * shouldn't get a 0 return when splitting an extent unless
+		 * shouldn't get a 0 allocated when splitting an extent unless
 		 * m_len is 0 (bug) or extent has been corrupted
 		 */
-		if (unlikely(ret == 0)) {
+		if (unlikely(allocated == 0)) {
 			EXT4_ERROR_INODE(inode,
-					 "unexpected ret == 0, m_len = %u",
+					 "unexpected allocated == 0, m_len = %u",
 					 map->m_len);
 			err = -EFSCORRUPTED;
 			goto out2;
@@ -3989,9 +3990,9 @@ ext4_ext_handle_unwritten_extents(handle_t *handle, struct inode *inode,
 		err = -EFSCORRUPTED;
 		goto out2;
 	}
+	allocated = ret;
 
 out:
-	allocated = ret;
 	map->m_flags |= EXT4_MAP_NEW;
 map_out:
 	map->m_flags |= EXT4_MAP_MAPPED;