sysctl: Allow creating permanently empty directories that serve as mountpoints.
Add a magic sysctl table sysctl_mount_point that when used to
create a directory forces that directory to be permanently empty.
Update the code to use make_empty_dir_inode when accessing permanently
empty directories.
Update the code to not allow adding to permanently empty directories.
Update /proc/sys/fs/binfmt_misc to be a permanently empty directory.
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 795d5fe..fa7bc29 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -188,6 +188,9 @@
void unregister_sysctl_table(struct ctl_table_header * table);
extern int sysctl_init(void);
+
+extern struct ctl_table sysctl_mount_point[];
+
#else /* CONFIG_SYSCTL */
static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
{