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

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/mm/shmem.c b/mm/shmem.c
index 86a19ef..feead19 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2118,9 +2118,9 @@
 	return error;
 }
 
-static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs)
+static int shmem_show_options(struct seq_file *seq, struct dentry *root)
 {
-	struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb);
+	struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
 
 	if (sbinfo->max_blocks != shmem_default_max_blocks())
 		seq_printf(seq, ",size=%luk",