vfs: switch ->show_options() to struct dentry *

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index dc62d3c..ae488aa 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -661,9 +661,9 @@
 	return ret;
 }
 
-static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
+static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 {
-	struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
+	struct btrfs_root *root = btrfs_sb(dentry->d_sb);
 	struct btrfs_fs_info *info = root->fs_info;
 	char *compress_type;