diff -up btrfs-progs-0.19/mkfs.c.orig btrfs-progs-0.19/mkfs.c

--- btrfs-progs-0.19/mkfs.c.orig	2012-04-11 10:38:26.825973948 -0400

+++ btrfs-progs-0.19/mkfs.c	2012-04-11 10:39:46.031360540 -0400

@@ -372,7 +372,6 @@ static u64 parse_profile(char *s)

 static char *parse_label(char *input)

 {

-	int i;

 	int len = strlen(input);

 	if (len >= BTRFS_LABEL_SIZE) {

@@ -380,12 +379,6 @@ static char *parse_label(char *input)

 			BTRFS_LABEL_SIZE - 1);

 		exit(1);

 	}

-	for (i = 0; i < len; i++) {

-		if (input[i] == '/' || input[i] == '\\') {

-			fprintf(stderr, "invalid label %s\n", input);

-			exit(1);

-		}

-	}

 	return strdup(input);

 }