ext4: get rid of ppath in ext4_ext_handle_unwritten_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_ext_handle_unwritten_extents(), the
following is done here:

 * Free the extents path when an error is encountered.
 * The 'allocated' is changed from passing a value to passing an address.

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/20240822023545.1994557-22-libaokun@huaweicloud.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/extents.c

@@ -3888,18 +3888,18 @@ convert_initialized_extent(handle_t *handle, struct inode *inode,
 	return 0;
 }
 
-static int
+static struct ext4_ext_path *
 ext4_ext_handle_unwritten_extents(handle_t *handle, struct inode *inode,
 			struct ext4_map_blocks *map,
-			struct ext4_ext_path **ppath, int flags,
-			unsigned int allocated, ext4_fsblk_t newblock)
+			struct ext4_ext_path *path, int flags,
+			unsigned int *allocated, ext4_fsblk_t newblock)
 {
 	int err = 0;
 
 	ext_debug(inode, "logical block %llu, max_blocks %u, flags 0x%x, allocated %u\n",
 		  (unsigned long long)map->m_lblk, map->m_len, flags,
-		  allocated);
-	ext4_ext_show_leaf(inode, *ppath);
+		  *allocated);
+	ext4_ext_show_leaf(inode, path);
 
 	/*
 	 * When writing into unwritten space, we should not fail to
@@ -3908,40 +3908,34 @@ ext4_ext_handle_unwritten_extents(handle_t *handle, struct inode *inode,
 	flags |= EXT4_GET_BLOCKS_METADATA_NOFAIL;
 
 	trace_ext4_ext_handle_unwritten_extents(inode, map, flags,
-						    allocated, newblock);
+						*allocated, newblock);
 
 	/* get_block() before submitting IO, split the extent */
 	if (flags & EXT4_GET_BLOCKS_PRE_IO) {
-		*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;
-		}
+		path = ext4_split_convert_extents(handle, inode, map, path,
+				flags | EXT4_GET_BLOCKS_CONVERT, allocated);
+		if (IS_ERR(path))
+			return path;
 		/*
 		 * shouldn't get a 0 allocated when splitting an extent unless
 		 * m_len is 0 (bug) or extent has been corrupted
 		 */
-		if (unlikely(allocated == 0)) {
+		if (unlikely(*allocated == 0)) {
 			EXT4_ERROR_INODE(inode,
 					 "unexpected allocated == 0, m_len = %u",
 					 map->m_len);
 			err = -EFSCORRUPTED;
-			goto out2;
+			goto errout;
 		}
 		map->m_flags |= EXT4_MAP_UNWRITTEN;
 		goto out;
 	}
 	/* IO end_io complete, convert the filled extent to written */
 	if (flags & EXT4_GET_BLOCKS_CONVERT) {
-		*ppath = ext4_convert_unwritten_extents_endio(handle, inode,
-							      map, *ppath);
-		if (IS_ERR(*ppath)) {
-			err = PTR_ERR(*ppath);
-			*ppath = NULL;
-			goto out2;
-		}
+		path = ext4_convert_unwritten_extents_endio(handle, inode,
+							    map, path);
+		if (IS_ERR(path))
+			return path;
 		ext4_update_inode_fsync_trans(handle, inode, 1);
 		goto map_out;
 	}
@@ -3973,23 +3967,20 @@ ext4_ext_handle_unwritten_extents(handle_t *handle, struct inode *inode,
 	 * For buffered writes, at writepage time, etc.  Convert a
 	 * discovered unwritten extent to written.
 	 */
-	*ppath = ext4_ext_convert_to_initialized(handle, inode, map, *ppath,
-						 flags, &allocated);
-	if (IS_ERR(*ppath)) {
-		err = PTR_ERR(*ppath);
-		*ppath = NULL;
-		goto out2;
-	}
+	path = ext4_ext_convert_to_initialized(handle, inode, map, path,
+					       flags, allocated);
+	if (IS_ERR(path))
+		return path;
 	ext4_update_inode_fsync_trans(handle, inode, 1);
 	/*
 	 * shouldn't get a 0 allocated when converting an unwritten extent
 	 * unless m_len is 0 (bug) or extent has been corrupted
 	 */
-	if (unlikely(allocated == 0)) {
+	if (unlikely(*allocated == 0)) {
 		EXT4_ERROR_INODE(inode, "unexpected allocated == 0, m_len = %u",
 				 map->m_len);
 		err = -EFSCORRUPTED;
-		goto out2;
+		goto errout;
 	}
 
 out:
@@ -3998,12 +3989,15 @@ ext4_ext_handle_unwritten_extents(handle_t *handle, struct inode *inode,
 	map->m_flags |= EXT4_MAP_MAPPED;
 out1:
 	map->m_pblk = newblock;
-	if (allocated > map->m_len)
-		allocated = map->m_len;
-	map->m_len = allocated;
-	ext4_ext_show_leaf(inode, *ppath);
-out2:
-	return err ? err : allocated;
+	if (*allocated > map->m_len)
+		*allocated = map->m_len;
+	map->m_len = *allocated;
+	ext4_ext_show_leaf(inode, path);
+	return path;
+
+errout:
+	ext4_free_ext_path(path);
+	return ERR_PTR(err);
 }
 
 /*
@@ -4201,7 +4195,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 	struct ext4_extent newex, *ex, ex2;
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 	ext4_fsblk_t newblock = 0, pblk;
-	int err = 0, depth, ret;
+	int err = 0, depth;
 	unsigned int allocated = 0, offset = 0;
 	unsigned int allocated_clusters = 0;
 	struct ext4_allocation_request ar;
@@ -4275,13 +4269,11 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 				goto out;
 			}
 
-			ret = ext4_ext_handle_unwritten_extents(
-				handle, inode, map, &path, flags,
-				allocated, newblock);
-			if (ret < 0)
-				err = ret;
-			else
-				allocated = ret;
+			path = ext4_ext_handle_unwritten_extents(
+				handle, inode, map, path, flags,
+				&allocated, newblock);
+			if (IS_ERR(path))
+				err = PTR_ERR(path);
 			goto out;
 		}
 	}