diff --git a/cmd_format.c b/cmd_format.c
index fff2d77b..065efd9d 100644
--- a/cmd_format.c
+++ b/cmd_format.c
@@ -30,19 +30,20 @@
 
 #define OPTS									\
 t("bcachefs format - create a new bcachefs filesystem on one or more devices")	\
-t("Usage: bcachefs format [OPTION]... <devices>")					\
+t("Usage: bcachefs format [OPTION]... <devices>")				\
 t("")										\
 x('b',	block_size,		"size",			NULL)			\
 x(0,	btree_node_size,	"size",			"Default 256k")		\
 x(0,	metadata_checksum_type,	"(none|crc32c|crc64)",	NULL)			\
 x(0,	data_checksum_type,	"(none|crc32c|crc64)",	NULL)			\
 x(0,	compression_type,	"(none|lz4|gzip)",	NULL)			\
+x(0,	background_compression_type,	"(none|lz4|gzip)",	NULL)		\
 x(0,	replicas,		"#",			NULL)			\
 x(0,	data_replicas,		"#",			NULL)			\
 x(0,	metadata_replicas,	"#",			NULL)			\
 x(0,	foreground_target,	"target",		NULL)			\
 x(0,	background_target,	"target",		NULL)			\
-x(0,	promote_target,	"target",		NULL)			\
+x(0,	promote_target,		"target",		NULL)			\
 x(0,	encrypted,		NULL,			"Enable whole filesystem encryption (chacha20/poly1305)")\
 x(0,	no_passphrase,		NULL,			"Don't encrypt master encryption key")\
 x('e',	error_action,		"(continue|remount-ro|panic)", NULL)		\
@@ -78,7 +79,8 @@ static void usage(void)
 	     "      --btree_node=size       Btree node size, default 256k\n"
 	     "      --metadata_checksum_type=(none|crc32c|crc64)\n"
 	     "      --data_checksum_type=(none|crc32c|crc64)\n"
-	     "      --compression_type=(none|lz4|gzip)\n"
+	     "      --compression_type=(none|lz4|gzip|zstd)\n"
+	     "      --background_compression_type=(none|lz4|gzip|zstd)\n"
 	     "      --data_replicas=#       Number of data replicas\n"
 	     "      --metadata_replicas=#   Number of metadata replicas\n"
 	     "      --replicas=#            Sets both data and metadata replicas\n"
@@ -178,6 +180,12 @@ int cmd_format(int argc, char *argv[])
 						bch2_compression_types,
 						"compression type");
 			break;
+		case O_background_compression_type:
+			opts.background_compression_type =
+				read_string_list_or_die(optarg,
+						bch2_compression_types,
+						"compression type");
+			break;
 		case O_data_replicas:
 			if (kstrtouint(optarg, 10, &opts.data_replicas) ||
 			    !opts.data_replicas ||
diff --git a/libbcachefs.c b/libbcachefs.c
index 9baaff04..cd277fa7 100644
--- a/libbcachefs.c
+++ b/libbcachefs.c
@@ -128,8 +128,8 @@ static unsigned parse_target(struct dev_opts *devs, size_t nr_devs,
 			     struct bch_sb_field_disk_groups *gi,
 			     const char *s)
 {
-	struct bch_disk_group *g;
 	struct dev_opts *i;
+	int idx;
 
 	if (!s)
 		return 0;
@@ -138,15 +138,9 @@ static unsigned parse_target(struct dev_opts *devs, size_t nr_devs,
 		if (!strcmp(s, i->path))
 			return dev_to_target(i - devs);
 
-	for (g = gi->entries;
-	     g < gi->entries + disk_groups_nr(gi);
-	     g++) {
-		unsigned len = strnlen(g->label, sizeof(g->label));
-
-		if (len == strlen(s) &&
-		    !memcmp(s, g->label, len))
-			return group_to_target(g - gi->entries);
-	}
+	idx = __bch2_disk_group_find(gi, s);
+	if (idx >= 0)
+		return group_to_target(idx);
 
 	die("Invalid target %s", s);
 	return 0;
@@ -212,6 +206,7 @@ struct bch_sb *bch2_format(struct format_opts opts,
 	SET_BCH_SB_META_CSUM_TYPE(sb,		opts.meta_csum_type);
 	SET_BCH_SB_DATA_CSUM_TYPE(sb,		opts.data_csum_type);
 	SET_BCH_SB_COMPRESSION_TYPE(sb,		opts.compression_type);
+	SET_BCH_SB_BACKGROUND_COMPRESSION_TYPE(sb, opts.background_compression_type);
 
 	SET_BCH_SB_BTREE_NODE_SIZE(sb,		opts.btree_node_size);
 	SET_BCH_SB_GC_RESERVE(sb,		8);
@@ -446,11 +441,15 @@ static void bch2_sb_print_members(struct bch_sb *sb, struct bch_sb_field *f,
 		uuid_unparse(m->uuid.b, member_uuid_str);
 
 		if (BCH_MEMBER_GROUP(m)) {
-			if (BCH_MEMBER_GROUP(m) < disk_groups_nr(gi))
-				memcpy(group, gi->entries[BCH_MEMBER_GROUP(m)].label,
+			unsigned idx = BCH_MEMBER_GROUP(m) - 1;
+
+			if (idx < disk_groups_nr(gi)) {
+				memcpy(group, gi->entries[idx].label,
 				       BCH_SB_LABEL_SIZE);
-			else
+				group[BCH_SB_LABEL_SIZE] = '\0';
+			} else {
 				strcpy(group, "(bad disk groups section");
+			}
 		}
 
 		bch2_scnprint_flag_list(data_allowed_str,
diff --git a/libbcachefs.h b/libbcachefs.h
index d27b4e8f..deaa2875 100644
--- a/libbcachefs.h
+++ b/libbcachefs.h
@@ -32,6 +32,7 @@ struct format_opts {
 	unsigned	meta_csum_type;
 	unsigned	data_csum_type;
 	unsigned	compression_type;
+	unsigned	background_compression_type;
 
 	bool		encrypted;
 	char		*passphrase;