[SCSI] iscsi: Some fixes in preparation for bidirectional support - exp_datasn

This patch fixes handling of expected datasn/r2tsn as received from
target. It is done according to: T10 rfc3720 section 3.2.2.3. Data Sequencing.

. unify expected datasn/r2tsn into one counter
. calculate than check expected datasn/r2tsn. On error print a message
  and fail the request. (TODO use iscsi retransmits)
. remove the FIXME   ;)
. avoid zero length memset

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 5e6a42429c39..eb5113607958 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -120,7 +120,9 @@ static void iscsi_prep_scsi_cmd_pdu(struct iscsi_cmd_task *ctask)
         session->cmdsn++;
         hdr->exp_statsn = cpu_to_be32(conn->exp_statsn);
         memcpy(hdr->cdb, sc->cmnd, sc->cmd_len);
-        memset(&hdr->cdb[sc->cmd_len], 0, MAX_COMMAND_SIZE - sc->cmd_len);
+        if (sc->cmd_len < MAX_COMMAND_SIZE)
+                memset(&hdr->cdb[sc->cmd_len], 0,
+                        MAX_COMMAND_SIZE - sc->cmd_len);
 
         ctask->data_count = 0;
         if (sc->sc_data_direction == DMA_TO_DEVICE) {
@@ -165,7 +167,6 @@ static void iscsi_prep_scsi_cmd_pdu(struct iscsi_cmd_task *ctask)
                         /* No unsolicit Data-Out's */
                         ctask->hdr->flags |= ISCSI_FLAG_CMD_FINAL;
         } else {
-                ctask->datasn = 0;
                 hdr->flags |= ISCSI_FLAG_CMD_FINAL;
                 zero_data(hdr->dlength);