Move grabbing s_umount to callers of grab_super()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/super.c b/fs/super.c
index dba74e7..61fa181 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -210,7 +210,6 @@
 {
 	if (atomic_inc_not_zero(&s->s_active)) {
 		spin_unlock(&sb_lock);
-		down_write(&s->s_umount);
 		return 1;
 	}
 	/* it's going away */
@@ -317,6 +316,7 @@
 				up_write(&s->s_umount);
 				destroy_super(s);
 			}
+			down_write(&old->s_umount);
 			return old;
 		}
 	}
@@ -466,7 +466,7 @@
  *
  * Scans the superblock list and finds the superblock of the file system
  * mounted on the device given.  Returns the superblock with an active
- * reference and s_umount held exclusively or %NULL if none was found.
+ * reference or %NULL if none was found.
  */
 struct super_block *get_active_super(struct block_device *bdev)
 {