target: Handle ATA_16 passthrough for pSCSI backend devices

The cdrecord uses ATA_PASS_THROUGH_16 command while burning CDs
with a SATA CD-ROM. This patch adds support to it so that PSCSI
CD-ROM passthrough works with the cdrecord.

(nab: Add !passthrough check to prevent non pSCSI backends from ATA_16)

Signed-off-by: Cong Meng <mc@linux.vnet.ibm.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 32 insertions, 0 deletions

diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index f95a74da4d40..b05fdc0c05d3 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2927,6 +2927,38 @@ static int transport_generic_cmd_sequencer(
                 size = (cdb[7] << 8) | cdb[8];
                 cmd->se_cmd_flags |= SCF_SCSI_CONTROL_SG_IO_CDB;
                 break;
+        case ATA_16:
+                /* Only support ATA passthrough to pSCSI backends.. */
+                if (!passthrough)
+                        goto out_unsupported_cdb;
+
+                /* T_LENGTH */
+                switch (cdb[2] & 0x3) {
+                case 0x0:
+                        sectors = 0;
+                        break;
+                case 0x1:
+                        sectors = (((cdb[1] & 0x1) ? cdb[3] : 0) << 8) | cdb[4];
+                        break;
+                case 0x2:
+                        sectors = (((cdb[1] & 0x1) ? cdb[5] : 0) << 8) | cdb[6];
+                        break;
+                case 0x3:
+                        pr_err("T_LENGTH=0x3 not supported for ATA_16\n");
+                        goto out_invalid_cdb_field;
+                }
+
+                /* BYTE_BLOCK */
+                if (cdb[2] & 0x4) {
+                        /* BLOCK T_TYPE: 512 or sector */
+                        size = sectors * ((cdb[2] & 0x10) ?
+                                dev->se_sub_dev->se_dev_attrib.block_size : 512);
+                } else {
+                        /* BYTE */
+                        size = sectors;
+                }
+                cmd->se_cmd_flags |= SCF_SCSI_CONTROL_SG_IO_CDB;
+                break;
         default:
                 pr_warn("TARGET_CORE[%s]: Unsupported SCSI Opcode"
                         " 0x%02x, sending CHECK_CONDITION.\n",