afs: Implement show_options

Implement the show_options superblock op for afs as part of a bid to get
rid of s_options and generic_show_options() to make it easier to implement
a context-based mount where the mount options can be passed individually
over a file descriptor.

Also implement the show_devname op to display the correct device name and thus
avoid the need to display the cell= and volume= options.

Signed-off-by: David Howells <[e-mail]>
cc: [e-mail]
Signed-off-by: Al Viro <[e-mail]>

fs/afs/super.c

···
 static struct inode *afs_alloc_inode(struct super_block *sb);
 static void afs_destroy_inode(struct inode *inode);
 static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
+static int afs_show_devname(struct seq_file *m, struct dentry *root);
+static int afs_show_options(struct seq_file *m, struct dentry *root);
 
 struct file_system_type afs_fs_type = {
 	.owner		= THIS_MODULE,
···
 	.drop_inode	= afs_drop_inode,
 	.destroy_inode	= afs_destroy_inode,
 	.evict_inode	= afs_evict_inode,
-	.show_options	= generic_show_options,
+	.show_devname	= afs_show_devname,
+	.show_options	= afs_show_options,
 };
 
 static struct kmem_cache *afs_inode_cachep;
···
 	rcu_barrier();
 	kmem_cache_destroy(afs_inode_cachep);
 	_leave("");
+}
+
+/*
+ * Display the mount device name in /proc/mounts.
+ */
+static int afs_show_devname(struct seq_file *m, struct dentry *root)
+{
+	struct afs_super_info *as = root->d_sb->s_fs_info;
+	struct afs_volume *volume = as->volume;
+	struct afs_cell *cell = volume->cell;
+	const char *suf = "";
+	char pref = '%';
+
+	switch (volume->type) {
+	case AFSVL_RWVOL:
+		break;
+	case AFSVL_ROVOL:
+		pref = '#';
+		if (volume->type_force)
+			suf = ".readonly";
+		break;
+	case AFSVL_BACKVOL:
+		pref = '#';
+		suf = ".backup";
+		break;
+	}
+
+	seq_printf(m, "%c%s:%s%s", pref, cell->name, volume->vlocation->vldb.name, suf);
+	return 0;
+}
+
+/*
+ * Display the mount options in /proc/mounts.
+ */
+static int afs_show_options(struct seq_file *m, struct dentry *root)
+{
+	if (test_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(d_inode(root))->flags))
+		seq_puts(m, "autocell");
+	return 0;
 }
 
 /*
···
 			deactivate_locked_super(sb);
 			goto error;
 		}
-		save_mount_options(sb, new_opts);
 		sb->s_flags |= MS_ACTIVE;
 	} else {
 		_debug("reuse");