ext4: Annotate struct fname with __counted_by()

Add the __counted_by compiler attribute to the flexible array member name to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and CONFIG_FORTIFY_SOURCE.

---
Changes in v2:
- Split the patch into two separate patches as suggested by Greg KH
- Link to v1: https://lore.kernel.org/r/[email protected]/

---
 fs/ext4/dir.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index ef6a3c8f3a9a..233479647f1b 100644
@@ -418,7 +418,7 @@ struct fname {
 	__u32		inode;
 	__u8		name_len;
 	__u8		file_type;
-	char		name[];
+	char		name[] __counted_by(name_len);
 };
 
 /*

2.47.0