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

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index dd74d3b..6e6faa1 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -263,7 +263,7 @@
 static void nfs_umount_begin(struct super_block *);
 static int  nfs_statfs(struct dentry *, struct kstatfs *);
 static int  nfs_show_options(struct seq_file *, struct vfsmount *);
-static int  nfs_show_devname(struct seq_file *, struct vfsmount *);
+static int  nfs_show_devname(struct seq_file *, struct dentry *);
 static int  nfs_show_path(struct seq_file *, struct vfsmount *);
 static int  nfs_show_stats(struct seq_file *, struct dentry *);
 static struct dentry *nfs_fs_mount(struct file_system_type *,
@@ -760,14 +760,14 @@
 #endif
 #endif
 
-static int nfs_show_devname(struct seq_file *m, struct vfsmount *mnt)
+static int nfs_show_devname(struct seq_file *m, struct dentry *root)
 {
 	char *page = (char *) __get_free_page(GFP_KERNEL);
 	char *devname, *dummy;
 	int err = 0;
 	if (!page)
 		return -ENOMEM;
-	devname = nfs_path(&dummy, mnt->mnt_root, page, PAGE_SIZE);
+	devname = nfs_path(&dummy, root, page, PAGE_SIZE);
 	if (IS_ERR(devname))
 		err = PTR_ERR(devname);
 	else
diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
index 61a09a6..6d4583d 100644
--- a/fs/proc_namespace.c
+++ b/fs/proc_namespace.c
@@ -94,9 +94,10 @@
 	struct mount *r = real_mount(mnt);
 	int err = 0;
 	struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
+	struct super_block *sb = mnt_path.dentry->d_sb;
 
-	if (mnt->mnt_sb->s_op->show_devname) {
-		err = mnt->mnt_sb->s_op->show_devname(m, mnt);
+	if (sb->s_op->show_devname) {
+		err = sb->s_op->show_devname(m, mnt_path.dentry);
 		if (err)
 			goto out;
 	} else {
@@ -105,14 +106,14 @@
 	seq_putc(m, ' ');
 	seq_path(m, &mnt_path, " \t\n\\");
 	seq_putc(m, ' ');
-	show_type(m, mnt->mnt_sb);
+	show_type(m, sb);
 	seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw");
-	err = show_sb_opts(m, mnt->mnt_sb);
+	err = show_sb_opts(m, sb);
 	if (err)
 		goto out;
 	show_mnt_opts(m, mnt);
-	if (mnt->mnt_sb->s_op->show_options)
-		err = mnt->mnt_sb->s_op->show_options(m, mnt);
+	if (sb->s_op->show_options)
+		err = sb->s_op->show_options(m, mnt);
 	seq_puts(m, " 0 0\n");
 out:
 	return err;
@@ -163,7 +164,7 @@
 	show_type(m, sb);
 	seq_putc(m, ' ');
 	if (sb->s_op->show_devname)
-		err = sb->s_op->show_devname(m, mnt);
+		err = sb->s_op->show_devname(m, mnt->mnt_root);
 	else
 		mangle(m, r->mnt_devname ? r->mnt_devname : "none");
 	if (err)
@@ -189,7 +190,7 @@
 	/* device */
 	if (sb->s_op->show_devname) {
 		seq_puts(m, "device ");
-		err = sb->s_op->show_devname(m, mnt);
+		err = sb->s_op->show_devname(m, mnt_path.dentry);
 	} else {
 		if (r->mnt_devname) {
 			seq_puts(m, "device ");
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b2e4b6f..a8dff43 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1673,7 +1673,7 @@
 	void (*umount_begin) (struct super_block *);
 
 	int (*show_options)(struct seq_file *, struct vfsmount *);
-	int (*show_devname)(struct seq_file *, struct vfsmount *);
+	int (*show_devname)(struct seq_file *, struct dentry *);
 	int (*show_path)(struct seq_file *, struct vfsmount *);
 	int (*show_stats)(struct seq_file *, struct dentry *);
 #ifdef CONFIG_QUOTA