ocfs2: Add the 'inode64' mount option.

Now that ocfs2 limits inode numbers to 32bits, add a mount option to
disable the limit.  This parallels XFS.  64bit systems can handle the
larger inode numbers.

[ Added description of inode64 mount option in ocfs2.txt. --Mark ]

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

fs/ocfs2/super.c

@@ -157,6 +157,7 @@ enum {
 	Opt_stack,
 	Opt_user_xattr,
 	Opt_nouser_xattr,
+	Opt_inode64,
 	Opt_err,
 };
 
@@ -178,6 +179,7 @@ static const match_table_t tokens = {
 	{Opt_stack, "cluster_stack=%s"},
 	{Opt_user_xattr, "user_xattr"},
 	{Opt_nouser_xattr, "nouser_xattr"},
+	{Opt_inode64, "inode64"},
 	{Opt_err, NULL}
 };
 
@@ -411,6 +413,15 @@ static int ocfs2_remount(struct super_block *sb, int *flags, char *data)
 		goto out;
 	}
 
+	/* Probably don't want this on remount; it might
+	 * mess with other nodes */
+	if (!(osb->s_mount_opt & OCFS2_MOUNT_INODE64) &&
+	    (parsed_options.mount_opt & OCFS2_MOUNT_INODE64)) {
+		ret = -EINVAL;
+		mlog(ML_ERROR, "Cannot enable inode64 on remount\n");
+		goto out;
+	}
+
 	/* We're going to/from readonly mode. */
 	if ((*flags & MS_RDONLY) != (sb->s_flags & MS_RDONLY)) {
 		/* Lock here so the check of HARD_RO and the potential
@@ -930,6 +941,9 @@ static int ocfs2_parse_options(struct super_block *sb,
 			       OCFS2_STACK_LABEL_LEN);
 			mopt->cluster_stack[OCFS2_STACK_LABEL_LEN] = '\0';
 			break;
+		case Opt_inode64:
+			mopt->mount_opt |= OCFS2_MOUNT_INODE64;
+			break;
 		default:
 			mlog(ML_ERROR,
 			     "Unrecognized mount option \"%s\" "
@@ -994,6 +1008,9 @@ static int ocfs2_show_options(struct seq_file *s, struct vfsmount *mnt)
 		seq_printf(s, ",cluster_stack=%.*s", OCFS2_STACK_LABEL_LEN,
 			   osb->osb_cluster_stack);
 
+	if (opts & OCFS2_MOUNT_INODE64)
+		seq_printf(s, ",inode64");
+
 	return 0;
 }