vfs: simple_set_mnt() should return void

simple_set_mnt() is defined as returning 'int' but always returns 0.
Callers assume simple_set_mnt() never fails and don't properly cleanup if
it were to _ever_ fail.  For instance, get_sb_single() and get_sb_nodev()
should:

        up_write(sb->s_unmount);
        deactivate_super(sb);

if simple_set_mnt() fails.

Since simple_set_mnt() never fails, would be cleaner if it did not
return anything.

[akpm@linux-foundation.org: fix build]
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c2c4454..a7d7391 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1719,7 +1719,7 @@
 extern int get_sb_pseudo(struct file_system_type *, char *,
 	const struct super_operations *ops, unsigned long,
 	struct vfsmount *mnt);
-extern int simple_set_mnt(struct vfsmount *mnt, struct super_block *sb);
+extern void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb);
 int __put_super_and_need_restart(struct super_block *sb);
 
 /* Alas, no aliases. Too much hassle with bringing module.h everywhere */