ext4: Limit number of links that can be created by ext4_link()

In ext4_link we need to check using EXT4_LINK_MAX, and not
EXT4_DIR_LINK_MAX(), since ext4_link() is creating hard links of
regular files, and not directories.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/namei.c

@@ -2318,7 +2318,7 @@ static int ext4_link(struct dentry *old_dentry,
 	struct inode *inode = old_dentry->d_inode;
 	int err, retries = 0;
 
-	if (EXT4_DIR_LINK_MAX(inode))
+	if (inode->i_nlink >= EXT4_LINK_MAX)
 		return -EMLINK;
 
 	/*