btrfs: btrfs_test_opt and friends should take a btrfs_fs_info

btrfs_test_opt and friends only use the root pointer to access
the fs_info.  Let's pass the fs_info directly in preparation to
eliminate similar patterns all over btrfs.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 0517356..ffb1628 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2406,7 +2406,7 @@
 		 * rmdir(2).
 		 */
 		err = -EPERM;
-		if (!btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
+		if (!btrfs_test_opt(root->fs_info, USER_SUBVOL_RM_ALLOWED))
 			goto out_dput;
 
 		/*