btrfs: add missing options displayed in mount output

There are three missed mount options settable by user which are not
currently displayed in mount output.

Signed-off-by: David Sterba <[e-mail]>
Signed-off-by: Chris Mason <[e-mail]>

fs/btrfs/ctree.h

···
  */
 #define BTRFS_STRING_ITEM_KEY	253
 
+/*
+ * Flags for mount options.
+ *
+ * Note: don't forget to add new options to btrfs_show_options()
+ */
 #define BTRFS_MOUNT_NODATASUM		(1 << 0)
 #define BTRFS_MOUNT_NODATACOW		(1 << 1)
 #define BTRFS_MOUNT_NOBARRIER		(1 << 2)

fs/btrfs/super.c

···
 		seq_puts(seq, ",clear_cache");
 	if (btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
 		seq_puts(seq, ",user_subvol_rm_allowed");
+	if (btrfs_test_opt(root, ENOSPC_DEBUG))
+		seq_puts(seq, ",enospc_debug");
+	if (btrfs_test_opt(root, AUTO_DEFRAG))
+		seq_puts(seq, ",autodefrag");
+	if (btrfs_test_opt(root, INODE_MAP_CACHE))
+		seq_puts(seq, ",inode_cache");
 	return 0;
 }