commit 55e51eda4820ec5a1c1fc8693a51029f74eac2b9
author Sagi Grimberg <sagig@mellanox.com> Wed Mar 05 19:43:49 2014 +0200
committer Roland Dreier <roland@purestorage.com> Mon Mar 17 22:33:58 2014 -0700
tree 77198a5b21bff21aecc44f625b620efd2342d2f9
parent 177e31bd5a40999028f6694623ceea1bec5abff6

SCSI/libiscsi: Add check_protection callback for transports

iSCSI needs to be at least aware that a task involves protection
information.  In case it does, after the transaction completed libiscsi
will ask the transport to check the protection status of the
transaction.

Unlike transport errors, DIF errors should not prevent successful
completion of the transaction from the transport point of view, but
should be escelated to scsi mid-layer when constructing the scsi
result and sense data.

check_protection routine will return the ascq corresponding to the DIF
error that occured (or 0 if no error happened).

return ascq:
- 0x1: GUARD_CHECK_FAILED
- 0x2: APPTAG_CHECK_FAILED
- 0x3: REFTAG_CHECK_FAILED

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Alex Tabachnik <alext@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/scsi/libiscsi.c

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 4046241..3c11acf 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -395,6 +395,10 @@
 		if (rc)
 			return rc;
 	}
+
+	if (scsi_get_prot_op(sc) != SCSI_PROT_NORMAL)
+		task->protected = true;
+
 	if (sc->sc_data_direction == DMA_TO_DEVICE) {
 		unsigned out_len = scsi_out(sc)->length;
 		struct iscsi_r2t_info *r2t = &task->unsol_r2t;
@@ -823,6 +827,33 @@
 
 	sc->result = (DID_OK << 16) | rhdr->cmd_status;
 
+	if (task->protected) {
+		sector_t sector;
+		u8 ascq;
+
+		/**
+		 * Transports that didn't implement check_protection
+		 * callback but still published T10-PI support to scsi-mid
+		 * deserve this BUG_ON.
+		 **/
+		BUG_ON(!session->tt->check_protection);
+
+		ascq = session->tt->check_protection(task, &sector);
+		if (ascq) {
+			sc->result = DRIVER_SENSE << 24 |
+				     SAM_STAT_CHECK_CONDITION;
+			scsi_build_sense_buffer(1, sc->sense_buffer,
+						ILLEGAL_REQUEST, 0x10, ascq);
+			sc->sense_buffer[7] = 0xc; /* Additional sense length */
+			sc->sense_buffer[8] = 0;   /* Information desc type */
+			sc->sense_buffer[9] = 0xa; /* Additional desc length */
+			sc->sense_buffer[10] = 0x80; /* Validity bit */
+
+			put_unaligned_be64(sector, &sc->sense_buffer[12]);
+			goto out;
+		}
+	}
+
 	if (rhdr->response != ISCSI_STATUS_CMD_COMPLETED) {
 		sc->result = DID_ERROR << 16;
 		goto out;
@@ -1567,6 +1598,7 @@
 	task->have_checked_conn = false;
 	task->last_timeout = jiffies;
 	task->last_xfer = jiffies;
+	task->protected = false;
 	INIT_LIST_HEAD(&task->running);
 	return task;
 }