[SCSI] iscsi: bidi support at the generic libiscsi level

- prepare the additional bidi_read rlength header.
- access the right scsi_in() and/or scsi_out() side of things.
  also for resid.
- Handle BIDI underflow overflow from target

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Reviewed-by: Pete Wyckoff <pw@osc.edu>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 70 insertions, 15 deletions

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 2f6b0955ff01..010c1b9b178c 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -176,6 +176,31 @@ static int iscsi_prep_ecdb_ahs(struct iscsi_cmd_task *ctask)
         return 0;
 }
 
+static int iscsi_prep_bidi_ahs(struct iscsi_cmd_task *ctask)
+{
+        struct scsi_cmnd *sc = ctask->sc;
+        struct iscsi_rlength_ahdr *rlen_ahdr;
+        int rc;
+
+        rlen_ahdr = iscsi_next_hdr(ctask);
+        rc = iscsi_add_hdr(ctask, sizeof(*rlen_ahdr));
+        if (rc)
+                return rc;
+
+        rlen_ahdr->ahslength =
+                cpu_to_be16(sizeof(rlen_ahdr->read_length) +
+                                                  sizeof(rlen_ahdr->reserved));
+        rlen_ahdr->ahstype = ISCSI_AHSTYPE_RLENGTH;
+        rlen_ahdr->reserved = 0;
+        rlen_ahdr->read_length = cpu_to_be32(scsi_in(sc)->length);
+
+        debug_scsi("bidi-in rlen_ahdr->read_length(%d) "
+                   "rlen_ahdr->ahslength(%d)\n",
+                   be32_to_cpu(rlen_ahdr->read_length),
+                   be16_to_cpu(rlen_ahdr->ahslength));
+        return 0;
+}
+
 /**
  * iscsi_prep_scsi_cmd_pdu - prep iscsi scsi cmd pdu
  * @ctask: iscsi cmd task
@@ -200,7 +225,6 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_cmd_task *ctask)
         hdr->flags = ISCSI_ATTR_SIMPLE;
         int_to_scsilun(sc->device->lun, (struct scsi_lun *)hdr->lun);
         hdr->itt = build_itt(ctask->itt, session->age);
-        hdr->data_length = cpu_to_be32(scsi_bufflen(sc));
         hdr->cmdsn = cpu_to_be32(session->cmdsn);
         session->cmdsn++;
         hdr->exp_statsn = cpu_to_be32(conn->exp_statsn);
@@ -216,7 +240,15 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_cmd_task *ctask)
         memcpy(hdr->cdb, sc->cmnd, cmd_len);
 
         ctask->imm_count = 0;
+        if (scsi_bidi_cmnd(sc)) {
+                hdr->flags |= ISCSI_FLAG_CMD_READ;
+                rc = iscsi_prep_bidi_ahs(ctask);
+                if (rc)
+                        return rc;
+        }
         if (sc->sc_data_direction == DMA_TO_DEVICE) {
+                unsigned out_len = scsi_out(sc)->length;
+                hdr->data_length = cpu_to_be32(out_len);
                 hdr->flags |= ISCSI_FLAG_CMD_WRITE;
                 /*
                  * Write counters:
@@ -237,19 +269,19 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_cmd_task *ctask)
                 ctask->unsol_datasn = 0;
 
                 if (session->imm_data_en) {
-                        if (scsi_bufflen(sc) >= session->first_burst)
+                        if (out_len >= session->first_burst)
                                 ctask->imm_count = min(session->first_burst,
                                                         conn->max_xmit_dlength);
                         else
-                                ctask->imm_count = min(scsi_bufflen(sc),
+                                ctask->imm_count = min(out_len,
                                                         conn->max_xmit_dlength);
                         hton24(hdr->dlength, ctask->imm_count);
                 } else
                         zero_data(hdr->dlength);
 
                 if (!session->initial_r2t_en) {
-                        ctask->unsol_count = min((session->first_burst),
-                                (scsi_bufflen(sc))) - ctask->imm_count;
+                        ctask->unsol_count = min(session->first_burst, out_len)
+                                                             - ctask->imm_count;
                         ctask->unsol_offset = ctask->imm_count;
                 }
 
@@ -259,6 +291,7 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_cmd_task *ctask)
         } else {
                 hdr->flags |= ISCSI_FLAG_CMD_FINAL;
                 zero_data(hdr->dlength);
+                hdr->data_length = cpu_to_be32(scsi_in(sc)->length);
 
                 if (sc->sc_data_direction == DMA_FROM_DEVICE)
                         hdr->flags |= ISCSI_FLAG_CMD_READ;
@@ -277,10 +310,12 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_cmd_task *ctask)
                 return EIO;
 
         conn->scsicmd_pdus_cnt++;
-        debug_scsi("iscsi prep [%s cid %d sc %p cdb 0x%x itt 0x%x len %d "
-                "cmdsn %d win %d]\n",
-                sc->sc_data_direction == DMA_TO_DEVICE ? "write" : "read",
-                conn->id, sc, sc->cmnd[0], ctask->itt, scsi_bufflen(sc),
+        debug_scsi("iscsi prep [%s cid %d sc %p cdb 0x%x itt 0x%x "
+                "len %d bidi_len %d cmdsn %d win %d]\n",
+                scsi_bidi_cmnd(sc) ? "bidirectional" :
+                     sc->sc_data_direction == DMA_TO_DEVICE ? "write" : "read",
+                conn->id, sc, sc->cmnd[0], ctask->itt,
+                scsi_bufflen(sc), scsi_bidi_cmnd(sc) ? scsi_in(sc)->length : 0,
                 session->cmdsn, session->max_cmdsn - session->exp_cmdsn + 1);
         return 0;
 }
@@ -343,7 +378,12 @@ static void fail_command(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
                 conn->session->tt->cleanup_cmd_task(conn, ctask);
 
         sc->result = err;
-        scsi_set_resid(sc, scsi_bufflen(sc));
+        if (!scsi_bidi_cmnd(sc))
+                scsi_set_resid(sc, scsi_bufflen(sc));
+        else {
+                scsi_out(sc)->resid = scsi_out(sc)->length;
+                scsi_in(sc)->resid = scsi_in(sc)->length;
+        }
         if (conn->ctask == ctask)
                 conn->ctask = NULL;
         /* release ref from queuecommand */
@@ -478,6 +518,18 @@ invalid_datalen:
                            min_t(uint16_t, senselen, SCSI_SENSE_BUFFERSIZE));
         }
 
+        if (rhdr->flags & (ISCSI_FLAG_CMD_BIDI_UNDERFLOW |
+                           ISCSI_FLAG_CMD_BIDI_OVERFLOW)) {
+                int res_count = be32_to_cpu(rhdr->bi_residual_count);
+
+                if (scsi_bidi_cmnd(sc) && res_count > 0 &&
+                                (rhdr->flags & ISCSI_FLAG_CMD_BIDI_OVERFLOW ||
+                                 res_count <= scsi_in(sc)->length))
+                        scsi_in(sc)->resid = res_count;
+                else
+                        sc->result = (DID_BAD_TARGET << 16) | rhdr->cmd_status;
+        }
+
         if (rhdr->flags & (ISCSI_FLAG_CMD_UNDERFLOW |
                            ISCSI_FLAG_CMD_OVERFLOW)) {
                 int res_count = be32_to_cpu(rhdr->residual_count);
@@ -485,13 +537,11 @@ invalid_datalen:
                 if (res_count > 0 &&
                     (rhdr->flags & ISCSI_FLAG_CMD_OVERFLOW ||
                      res_count <= scsi_bufflen(sc)))
+                        /* write side for bidi or uni-io set_resid */
                         scsi_set_resid(sc, res_count);
                 else
                         sc->result = (DID_BAD_TARGET << 16) | rhdr->cmd_status;
-        } else if (rhdr->flags & (ISCSI_FLAG_CMD_BIDI_UNDERFLOW |
-                                  ISCSI_FLAG_CMD_BIDI_OVERFLOW))
-                sc->result = (DID_BAD_TARGET << 16) | rhdr->cmd_status;
-
+        }
 out:
         debug_scsi("done [sc %lx res %d itt 0x%x]\n",
                    (long)sc, sc->result, ctask->itt);
@@ -1147,7 +1197,12 @@ reject:
 fault:
         spin_unlock(&session->lock);
         debug_scsi("iscsi: cmd 0x%x is not queued (%d)\n", sc->cmnd[0], reason);
-        scsi_set_resid(sc, scsi_bufflen(sc));
+        if (!scsi_bidi_cmnd(sc))
+                scsi_set_resid(sc, scsi_bufflen(sc));
+        else {
+                scsi_out(sc)->resid = scsi_out(sc)->length;
+                scsi_in(sc)->resid = scsi_in(sc)->length;
+        }
         sc->scsi_done(sc);
         spin_lock(host->host_lock);
         return 0;