Index: uspace/srv/fs/mfs/mfs_ops.c
===================================================================
--- uspace/srv/fs/mfs/mfs_ops.c	(revision e2f706e3ea21cc61ee413bac5947584169d648d7)
+++ uspace/srv/fs/mfs/mfs_ops.c	(revision 736b07b371eff9ddb7417f9783783a70634cebb4)
@@ -64,7 +64,7 @@
 static int mfs_check_sanity(struct mfs_sb_info *sbi);
 static bool is_power_of_two(uint32_t n);
-static uint32_t mfs_size_block(service_id_t service_id);
-static uint64_t mfs_total_block_count(service_id_t service_id);
-static uint64_t mfs_free_block_count(service_id_t service_id);
+static int mfs_size_block(service_id_t service_id, uint32_t *size);
+static int mfs_total_block_count(service_id_t service_id, uint64_t *count);
+static int mfs_free_block_count(service_id_t service_id, uint64_t *count);
 
 static hash_table_t open_nodes;
@@ -1135,28 +1135,29 @@
 }
 
-static uint32_t
-mfs_size_block(service_id_t service_id)
-{
-	uint32_t block_size;
-
+static int
+mfs_size_block(service_id_t service_id, uint32_t *size)
+{
 	struct mfs_instance *inst;
-	int rc = mfs_instance_get(service_id, &inst);
+	int rc;
+
+	rc = mfs_instance_get(service_id, &inst);
 	if (rc != EOK)
 		return rc;
+
 	if (NULL == inst)
 		return ENOENT;
 	
-	block_size = inst->sbi->block_size;
-
-	return block_size;
-}
-
-static uint64_t
-mfs_total_block_count(service_id_t service_id)
-{
-	uint64_t block_total;
+	*size = inst->sbi->block_size;
+
+	return EOK;
+}
+
+static int
+mfs_total_block_count(service_id_t service_id, uint64_t *count)
+{
+	struct mfs_instance *inst;
+	int rc;
 	
-	struct mfs_instance *inst;
-	int rc = mfs_instance_get(service_id, &inst);
+	rc = mfs_instance_get(service_id, &inst);
 	if (rc != EOK)
 		return rc;
@@ -1165,11 +1166,11 @@
 		return ENOENT;
 	
-	block_total = (uint64_t) MFS_BMAP_SIZE_BITS(inst->sbi, BMAP_ZONE);
-
-	return block_total;
-}
-
-static uint64_t
-mfs_free_block_count(service_id_t service_id)
+	*count = (uint64_t) MFS_BMAP_SIZE_BITS(inst->sbi, BMAP_ZONE);
+
+	return EOK;
+}
+
+static int
+mfs_free_block_count(service_id_t service_id, uint64_t *count)
 {
 	uint32_t block_free;
@@ -1184,6 +1185,7 @@
 
 	mfs_count_free_zones(inst, &block_free);
-
-	return (uint64_t)block_free;
+	*count = block_free;
+
+	return EOK;
 }