Convert obvious places to deactivate_locked_super()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 3536bdb..6dfae5b 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -502,8 +502,7 @@
 
 	if (s->s_root) {
 		if ((flags ^ s->s_flags) & MS_RDONLY) {
-			up_write(&s->s_umount);
-			deactivate_super(s);
+			deactivate_locked_super(s);
 			error = -EBUSY;
 			goto error_close_devices;
 		}
@@ -517,8 +516,7 @@
 		error = btrfs_fill_super(s, fs_devices, data,
 					 flags & MS_SILENT ? 1 : 0);
 		if (error) {
-			up_write(&s->s_umount);
-			deactivate_super(s);
+			deactivate_locked_super(s);
 			goto error_free_subvol_name;
 		}
 
@@ -535,15 +533,13 @@
 		mutex_unlock(&s->s_root->d_inode->i_mutex);
 
 		if (IS_ERR(root)) {
-			up_write(&s->s_umount);
-			deactivate_super(s);
+			deactivate_locked_super(s);
 			error = PTR_ERR(root);
 			goto error_free_subvol_name;
 		}
 		if (!root->d_inode) {
 			dput(root);
-			up_write(&s->s_umount);
-			deactivate_super(s);
+			deactivate_locked_super(s);
 			error = -ENXIO;
 			goto error_free_subvol_name;
 		}