f2fs: avoid BUG_ON from check_nid_range and update return path in do_read_inode

In function check_nid_range, there is no need to trigger BUG_ON and make kernel stop.
Instead it could just check and indicate the inode number to be EINVAL.
Update the return path in do_read_inode to use the return from check_nid_range.

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
[Jaegeuk: replace BUG_ON with WARN_ON]
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

fs/f2fs/f2fs.h

@@ -515,9 +515,12 @@ static inline void mutex_unlock_op(struct f2fs_sb_info *sbi, enum lock_type t)
 /*
  * Check whether the given nid is within node id range.
  */
-static inline void check_nid_range(struct f2fs_sb_info *sbi, nid_t nid)
+static inline int check_nid_range(struct f2fs_sb_info *sbi, nid_t nid)
 {
-	BUG_ON((nid >= NM_I(sbi)->max_nid));
+	WARN_ON((nid >= NM_I(sbi)->max_nid));
+	if (nid >= NM_I(sbi)->max_nid)
+		return -EINVAL;
+	return 0;
 }
 
 #define F2FS_DEFAULT_ALLOCATED_BLOCKS	1

fs/f2fs/inode.c

@@ -44,7 +44,11 @@ static int do_read_inode(struct inode *inode)
 	struct f2fs_inode *ri;
 
 	/* Check if ino is within scope */
-	check_nid_range(sbi, inode->i_ino);
+	if (check_nid_range(sbi, inode->i_ino)) {
+		f2fs_msg(inode->i_sb, KERN_ERR, "bad inode number: %lu",
+			 (unsigned long) inode->i_ino);
+		return -EINVAL;
+	}
 
 	node_page = get_node_page(sbi, inode->i_ino);
 	if (IS_ERR(node_page))