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/drivers/mtd/mtdsuper.c b/drivers/mtd/mtdsuper.c
index 00d46e1..92285d0 100644
--- a/drivers/mtd/mtdsuper.c
+++ b/drivers/mtd/mtdsuper.c
@@ -81,13 +81,16 @@
 
 	/* go */
 	sb->s_flags |= MS_ACTIVE;
-	return simple_set_mnt(mnt, sb);
+	simple_set_mnt(mnt, sb);
+
+	return 0;
 
 	/* new mountpoint for an already mounted superblock */
 already_mounted:
 	DEBUG(1, "MTDSB: Device %d (\"%s\") is already mounted\n",
 	      mtd->index, mtd->name);
-	ret = simple_set_mnt(mnt, sb);
+	simple_set_mnt(mnt, sb);
+	ret = 0;
 	goto out_put;
 
 out_error: