hugetlbfs: Implement show_options

Implement the show_options superblock op for hugetlbfs as part of a bid to
get rid of s_options and generic_show_options() to make it easier to
implement a context-based mount where the mount options can be passed
individually over a file descriptor.

Note that the uid and gid should possibly be displayed relative to the
viewer's user namespace.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Nadia Yvette Chambers <nyc@holomorphy.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index b857fc8..3b6eeaa 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -262,6 +262,9 @@ struct hugetlbfs_sb_info {
 	spinlock_t	stat_lock;
 	struct hstate *hstate;
 	struct hugepage_subpool *spool;
+	kuid_t	uid;
+	kgid_t	gid;
+	umode_t mode;
 };
 
 static inline struct hugetlbfs_sb_info *HUGETLBFS_SB(struct super_block *sb)