Index: uspace/lib/libblock/libblock.c
===================================================================
--- uspace/lib/libblock/libblock.c	(revision dccf72146c31b468c546d35ed8f671e5e26cda76)
+++ uspace/lib/libblock/libblock.c	(revision 1ac3a52793b357f936bd41ef49db586aa1e5c1a3)
@@ -87,4 +87,5 @@
 static int write_blocks(devcon_t *devcon, bn_t ba, size_t cnt);
 static int get_block_size(int dev_phone, size_t *bsize);
+static int get_num_blocks(int dev_phone, bn_t *nblocks);
 
 static devcon_t *devcon_search(dev_handle_t dev_handle)
@@ -738,4 +739,21 @@
 }
 
+/** Get number of blocks on device.
+ *
+ * @param dev_handle	Device handle of the block device.
+ * @param nblocks	Output number of blocks.
+ *
+ * @return		EOK on success or negative error code on failure.
+ */
+int block_get_nblocks(dev_handle_t dev_handle, bn_t *nblocks)
+{
+	devcon_t *devcon;
+
+	devcon = devcon_search(dev_handle);
+	assert(devcon);
+	
+	return get_num_blocks(devcon->dev_phone, nblocks);
+}
+
 /** Read blocks from block device.
  *
@@ -789,4 +807,18 @@
 }
 
+/** Get total number of blocks on block device. */
+static int get_num_blocks(int dev_phone, bn_t *nblocks)
+{
+	ipcarg_t nb_l, nb_h;
+	int rc;
+
+	rc = async_req_0_2(dev_phone, BD_GET_NUM_BLOCKS, &nb_l, &nb_h);
+	if (rc == EOK) {
+		*nblocks = (bn_t) MERGE_LOUP32(nb_l, nb_h);
+	}
+
+	return rc;
+}
+
 /** @}
  */
Index: uspace/lib/libblock/libblock.h
===================================================================
--- uspace/lib/libblock/libblock.h	(revision dccf72146c31b468c546d35ed8f671e5e26cda76)
+++ uspace/lib/libblock/libblock.h	(revision 1ac3a52793b357f936bd41ef49db586aa1e5c1a3)
@@ -60,6 +60,4 @@
 #define BLOCK_FLAGS_NOREAD	1
 
-typedef uint64_t bn_t;	/**< Block number type. */
-
 typedef struct block {
 	/** Mutex protecting the reference count. */
@@ -110,4 +108,5 @@
 
 extern int block_get_bsize(dev_handle_t, size_t *);
+extern int block_get_nblocks(dev_handle_t, bn_t *);
 extern int block_read_direct(dev_handle_t, bn_t, size_t, void *);
 extern int block_write_direct(dev_handle_t, bn_t, size_t, const void *);