ext4: use ERR_CAST to return an error-valued pointer

Instead of directly casting and returning an error-valued pointer,
use ERR_CAST to make the error handling more explicit and improve
code clarity.

Signed-off-by: Yu Jiaoliang <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>

Author: Yu Jiaoliang

fs/ext4/namei.c

@@ -1747,7 +1747,7 @@ static struct buffer_head * ext4_dx_find_entry(struct inode *dir,
 #endif
 	frame = dx_probe(fname, dir, NULL, frames);
 	if (IS_ERR(frame))
-		return (struct buffer_head *) frame;
+		return ERR_CAST(frame);
 	do {
 		block = dx_get_block(frame->at);
 		bh = ext4_read_dirblock(dir, block, DIRENT_HTREE);
@@ -1952,7 +1952,7 @@ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir,
 	if (IS_ERR(bh2)) {
 		brelse(*bh);
 		*bh = NULL;
-		return (struct ext4_dir_entry_2 *) bh2;
+		return ERR_CAST(bh2);
 	}
 
 	BUFFER_TRACE(*bh, "get_write_access");