diff --git a/src/arch/x86/interface/pcbios/int13.c b/src/arch/x86/interface/pcbios/int13.c
index 8ac14e58..ca789a0d 100644
--- a/src/arch/x86/interface/pcbios/int13.c
+++ b/src/arch/x86/interface/pcbios/int13.c
@@ -181,8 +181,8 @@ static int int13_parse_eltorito ( struct san_device *sandev, void *scratch ) {
 	int rc;
 
 	/* Read boot record volume descriptor */
-	if ( ( rc = sandev_rw ( sandev, ELTORITO_LBA, 1,
-				virt_to_user ( boot ), block_read ) ) != 0 ) {
+	if ( ( rc = sandev_read ( sandev, ELTORITO_LBA, 1,
+				  virt_to_user ( boot ) ) ) != 0 ) {
 		DBGC ( sandev, "INT13 drive %02x could not read El Torito boot "
 		       "record volume descriptor: %s\n",
 		       sandev->drive, strerror ( rc ) );
@@ -227,8 +227,7 @@ static int int13_guess_geometry_hdd ( struct san_device *sandev, void *scratch,
 	int rc;
 
 	/* Read partition table */
-	if ( ( rc = sandev_rw ( sandev, 0, 1, virt_to_user ( mbr ),
-				block_read ) ) != 0 ) {
+	if ( ( rc = sandev_read ( sandev, 0, 1, virt_to_user ( mbr ) ) ) != 0 ) {
 		DBGC ( sandev, "INT13 drive %02x could not read "
 		       "partition table to guess geometry: %s\n",
 		       sandev->drive, strerror ( rc ) );
@@ -506,18 +505,16 @@ static int int13_get_last_status ( struct san_device *sandev,
  * @v cl (bits 5:0)	Sector number
  * @v dh		Head number
  * @v es:bx		Data buffer
- * @v block_rw		Block read/write method
+ * @v sandev_rw		SAN device read/write method
  * @ret status		Status code
  * @ret al		Number of sectors read or written
  */
 static int int13_rw_sectors ( struct san_device *sandev,
 			      struct i386_all_regs *ix86,
-			      int ( * block_rw ) ( struct interface *control,
-						   struct interface *data,
-						   uint64_t lba,
-						   unsigned int count,
-						   userptr_t buffer,
-						   size_t len ) ) {
+			      int ( * sandev_rw ) ( struct san_device *sandev,
+						    uint64_t lba,
+						    unsigned int count,
+						    userptr_t buffer ) ) {
 	struct int13_data *int13 = sandev->priv;
 	unsigned int cylinder, head, sector;
 	unsigned long lba;
@@ -555,7 +552,7 @@ static int int13_rw_sectors ( struct san_device *sandev,
 		count );
 
 	/* Read from / write to block device */
-	if ( ( rc = sandev_rw ( sandev, lba, count, buffer, block_rw ) ) != 0 ){
+	if ( ( rc = sandev_rw ( sandev, lba, count, buffer ) ) != 0 ){
 		DBGC ( sandev, "INT13 drive %02x I/O failed: %s\n",
 		       sandev->drive, strerror ( rc ) );
 		return -INT13_STATUS_READ_ERROR;
@@ -581,7 +578,7 @@ static int int13_read_sectors ( struct san_device *sandev,
 				struct i386_all_regs *ix86 ) {
 
 	DBGC2 ( sandev, "Read: " );
-	return int13_rw_sectors ( sandev, ix86, block_read );
+	return int13_rw_sectors ( sandev, ix86, sandev_read );
 }
 
 /**
@@ -601,7 +598,7 @@ static int int13_write_sectors ( struct san_device *sandev,
 				 struct i386_all_regs *ix86 ) {
 
 	DBGC2 ( sandev, "Write: " );
-	return int13_rw_sectors ( sandev, ix86, block_write );
+	return int13_rw_sectors ( sandev, ix86, sandev_write );
 }
 
 /**
@@ -701,17 +698,15 @@ static int int13_extension_check ( struct san_device *sandev __unused,
  *
  * @v sandev		SAN device
  * @v ds:si		Disk address packet
- * @v block_rw		Block read/write method
+ * @v sandev_rw		SAN device read/write method
  * @ret status		Status code
  */
 static int int13_extended_rw ( struct san_device *sandev,
 			       struct i386_all_regs *ix86,
-			       int ( * block_rw ) ( struct interface *control,
-						    struct interface *data,
-						    uint64_t lba,
-						    unsigned int count,
-						    userptr_t buffer,
-						    size_t len ) ) {
+			       int ( * sandev_rw ) ( struct san_device *sandev,
+						     uint64_t lba,
+						     unsigned int count,
+						     userptr_t buffer ) ) {
 	struct int13_disk_address addr;
 	uint8_t bufsize;
 	uint64_t lba;
@@ -762,7 +757,7 @@ static int int13_extended_rw ( struct san_device *sandev,
 	DBGC2 ( sandev, " (count %ld)\n", count );
 
 	/* Read from / write to block device */
-	if ( ( rc = sandev_rw ( sandev, lba, count, buffer, block_rw ) ) != 0 ){
+	if ( ( rc = sandev_rw ( sandev, lba, count, buffer ) ) != 0 ) {
 		DBGC ( sandev, "INT13 drive %02x extended I/O failed: %s\n",
 		       sandev->drive, strerror ( rc ) );
 		/* Record that no blocks were transferred successfully */
@@ -787,7 +782,7 @@ static int int13_extended_read ( struct san_device *sandev,
 				 struct i386_all_regs *ix86 ) {
 
 	DBGC2 ( sandev, "Extended read: " );
-	return int13_extended_rw ( sandev, ix86, block_read );
+	return int13_extended_rw ( sandev, ix86, sandev_read );
 }
 
 /**
@@ -801,7 +796,7 @@ static int int13_extended_write ( struct san_device *sandev,
 				  struct i386_all_regs *ix86 ) {
 
 	DBGC2 ( sandev, "Extended write: " );
-	return int13_extended_rw ( sandev, ix86, block_write );
+	return int13_extended_rw ( sandev, ix86, sandev_write );
 }
 
 /**
@@ -1038,6 +1033,7 @@ static int int13_cdrom_read_boot_catalog ( struct san_device *sandev,
 					   struct i386_all_regs *ix86 ) {
 	struct int13_data *int13 = sandev->priv;
 	struct int13_cdrom_boot_catalog_command command;
+	unsigned int start;
 	int rc;
 
 	/* Read parameters from command packet */
@@ -1051,11 +1047,11 @@ static int int13_cdrom_read_boot_catalog ( struct san_device *sandev,
 		       sandev->drive );
 		return -INT13_STATUS_INVALID;
 	}
+	start = ( int13->boot_catalog + command.start );
 
 	/* Read from boot catalog */
-	if ( ( rc = sandev_rw ( sandev, ( int13->boot_catalog + command.start ),
-				command.count, phys_to_user ( command.buffer ),
-				block_read ) ) != 0 ) {
+	if ( ( rc = sandev_read ( sandev, start, command.count,
+				  phys_to_user ( command.buffer ) ) ) != 0 ) {
 		DBGC ( sandev, "INT13 drive %02x could not read boot catalog: "
 		       "%s\n", sandev->drive, strerror ( rc ) );
 		return -INT13_STATUS_READ_ERROR;
diff --git a/src/core/sanboot.c b/src/core/sanboot.c
index f134f76a..1fd63490 100644
--- a/src/core/sanboot.c
+++ b/src/core/sanboot.c
@@ -577,12 +577,12 @@ int sandev_reset ( struct san_device *sandev ) {
  * @v block_rw		Block read/write method
  * @ret rc		Return status code
  */
-int sandev_rw ( struct san_device *sandev, uint64_t lba,
-		unsigned int count, userptr_t buffer,
-		int ( * block_rw ) ( struct interface *control,
-				     struct interface *data,
-				     uint64_t lba, unsigned int count,
-				     userptr_t buffer, size_t len ) ) {
+static int sandev_rw ( struct san_device *sandev, uint64_t lba,
+		       unsigned int count, userptr_t buffer,
+		       int ( * block_rw ) ( struct interface *control,
+					    struct interface *data,
+					    uint64_t lba, unsigned int count,
+					    userptr_t buffer, size_t len ) ) {
 	union san_command_params params;
 	unsigned int remaining;
 	size_t frag_len;
@@ -617,6 +617,46 @@ int sandev_rw ( struct san_device *sandev, uint64_t lba,
 	return 0;
 }
 
+/**
+ * Read from SAN device
+ *
+ * @v sandev		SAN device
+ * @v lba		Starting logical block address
+ * @v count		Number of logical blocks
+ * @v buffer		Data buffer
+ * @ret rc		Return status code
+ */
+int sandev_read ( struct san_device *sandev, uint64_t lba,
+		  unsigned int count, userptr_t buffer ) {
+	int rc;
+
+	/* Read from device */
+	if ( ( rc = sandev_rw ( sandev, lba, count, buffer, block_read ) ) != 0 )
+		return rc;
+
+	return 0;
+}
+
+/**
+ * Write to SAN device
+ *
+ * @v sandev		SAN device
+ * @v lba		Starting logical block address
+ * @v count		Number of logical blocks
+ * @v buffer		Data buffer
+ * @ret rc		Return status code
+ */
+int sandev_write ( struct san_device *sandev, uint64_t lba,
+		   unsigned int count, userptr_t buffer ) {
+	int rc;
+
+	/* Write to device */
+	if ( ( rc = sandev_rw ( sandev, lba, count, buffer, block_write ) ) != 0 )
+		return rc;
+
+	return 0;
+}
+
 /**
  * Describe SAN device
  *
@@ -735,8 +775,8 @@ static int sandev_parse_iso9660 ( struct san_device *sandev ) {
 	}
 
 	/* Read primary volume descriptor */
-	if ( ( rc = sandev_rw ( sandev, lba, count, virt_to_user ( scratch ),
-				block_read ) ) != 0 ) {
+	if ( ( rc = sandev_read ( sandev, lba, count,
+				  virt_to_user ( scratch ) ) ) != 0 ) {
 		DBGC ( sandev, "SAN %#02x could not read ISO9660 primary"
 		       "volume descriptor: %s\n",
 		       sandev->drive, strerror ( rc ) );
diff --git a/src/include/ipxe/sanboot.h b/src/include/ipxe/sanboot.h
index 8b3e2b28..b163a94b 100644
--- a/src/include/ipxe/sanboot.h
+++ b/src/include/ipxe/sanboot.h
@@ -236,12 +236,10 @@ static inline int sandev_needs_reopen ( struct san_device *sandev ) {
 extern struct san_device * sandev_find ( unsigned int drive );
 extern int sandev_reopen ( struct san_device *sandev );
 extern int sandev_reset ( struct san_device *sandev );
-extern int sandev_rw ( struct san_device *sandev, uint64_t lba,
-		       unsigned int count, userptr_t buffer,
-		       int ( * block_rw ) ( struct interface *control,
-					    struct interface *data,
-					    uint64_t lba, unsigned int count,
-					    userptr_t buffer, size_t len ) );
+extern int sandev_read ( struct san_device *sandev, uint64_t lba,
+			 unsigned int count, userptr_t buffer );
+extern int sandev_write ( struct san_device *sandev, uint64_t lba,
+			  unsigned int count, userptr_t buffer );
 extern struct san_device * alloc_sandev ( struct uri **uris, unsigned int count,
 					  size_t priv_size );
 extern int register_sandev ( struct san_device *sandev, unsigned int drive,
diff --git a/src/interface/efi/efi_block.c b/src/interface/efi/efi_block.c
index 70a87dcf..c6445ab6 100644
--- a/src/interface/efi/efi_block.c
+++ b/src/interface/efi/efi_block.c
@@ -102,15 +102,14 @@ struct efi_block_data {
  * @v lba		Starting LBA
  * @v data		Data buffer
  * @v len		Size of buffer
- * @v block_rw		Block read/write method
+ * @v sandev_rw		SAN device read/write method
  * @ret rc		Return status code
  */
 static int efi_block_rw ( struct san_device *sandev, uint64_t lba,
 			  void *data, size_t len,
-			  int ( * block_rw ) ( struct interface *control,
-					       struct interface *data,
-					       uint64_t lba, unsigned int count,
-					       userptr_t buffer, size_t len ) ){
+			  int ( * sandev_rw ) ( struct san_device *sandev,
+						uint64_t lba, unsigned int count,
+						userptr_t buffer ) ) {
 	struct efi_block_data *block = sandev->priv;
 	unsigned int count;
 	int rc;
@@ -124,8 +123,8 @@ static int efi_block_rw ( struct san_device *sandev, uint64_t lba,
 	}
 
 	/* Read from / write to block device */
-	if ( ( rc = sandev_rw ( sandev, lba, count, virt_to_user ( data ),
-				block_rw ) ) != 0 ) {
+	if ( ( rc = sandev_rw ( sandev, lba, count,
+				virt_to_user ( data ) ) ) != 0 ) {
 		DBGC ( sandev, "EFIBLK %#02x I/O failed: %s\n",
 		       sandev->drive, strerror ( rc ) );
 		return rc;
@@ -176,7 +175,7 @@ efi_block_io_read ( EFI_BLOCK_IO_PROTOCOL *block_io, UINT32 media __unused,
 	DBGC2 ( sandev, "EFIBLK %#02x read LBA %#08llx to %p+%#08zx\n",
 		sandev->drive, lba, data, ( ( size_t ) len ) );
 	efi_snp_claim();
-	rc = efi_block_rw ( sandev, lba, data, len, block_read );
+	rc = efi_block_rw ( sandev, lba, data, len, sandev_read );
 	efi_snp_release();
 	return EFIRC ( rc );
 }
@@ -202,7 +201,7 @@ efi_block_io_write ( EFI_BLOCK_IO_PROTOCOL *block_io, UINT32 media __unused,
 	DBGC2 ( sandev, "EFIBLK %#02x write LBA %#08llx from %p+%#08zx\n",
 		sandev->drive, lba, data, ( ( size_t ) len ) );
 	efi_snp_claim();
-	rc = efi_block_rw ( sandev, lba, data, len, block_write );
+	rc = efi_block_rw ( sandev, lba, data, len, sandev_write );
 	efi_snp_release();
 	return EFIRC ( rc );
 }