[SCSI] libfc: add support of large receive offload by ddp in fc_fcp

When LLD supports direct data placement (ddp) for large receive of an scsi
i/o coming into fc_fcp, we call into libfc_function_template's ddp_setup()
to prepare for a ddp of large receive for this read I/O. When I/O is complete,
we call the corresponding ddp_done() to get the length of data ddped as well
as to let LLD do clean up.

fc_fcp_ddp_setup()/fc_fcp_ddp_done() are added to setup and complete a ddped
read I/O described by the given fc_fcp_pkt. They would call into corresponding
ddp_setup/ddp_done implemented by the fcoe layer. Eventually, fcoe layer calls
into LLD's ddp_setup/ddp_done provided through net_device

Signed-off-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

2 files changed, 63 insertions, 2 deletions

diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c
index 8a0c5c2..992af05 100644
--- a/drivers/scsi/libfc/fc_exch.c
+++ b/drivers/scsi/libfc/fc_exch.c
@@ -489,7 +489,7 @@ static u16 fc_em_alloc_xid(struct fc_exch_mgr *mp, const struct fc_frame *fp)
 	struct fc_exch *ep = NULL;
 
 	if (mp->max_read) {
-		if (fc_frame_is_read(fp)) {
+		if (fc_fcp_is_read(fr_fsp(fp))) {
 			min = mp->min_xid;
 			max = mp->max_read;
 			plast = &mp->last_read;
@@ -1841,6 +1841,8 @@ struct fc_seq *fc_exch_seq_send(struct fc_lport *lp,
 	fc_exch_setup_hdr(ep, fp, ep->f_ctl);
 	sp->cnt++;
 
+	fc_fcp_ddp_setup(fr_fsp(fp), ep->xid);
+
 	if (unlikely(lp->tt.frame_send(lp, fp)))
 		goto err;
 
diff --git a/drivers/scsi/libfc/fc_fcp.c b/drivers/scsi/libfc/fc_fcp.c
index 48adb89..a5725f3 100644
--- a/drivers/scsi/libfc/fc_fcp.c
+++ b/drivers/scsi/libfc/fc_fcp.c
@@ -265,6 +265,56 @@ static void fc_fcp_retry_cmd(struct fc_fcp_pkt *fsp)
 }
 
 /*
+ * fc_fcp_ddp_setup - calls to LLD's ddp_setup to set up DDP
+ * transfer for a read I/O indicated by the fc_fcp_pkt.
+ * @fsp: ptr to the fc_fcp_pkt
+ *
+ * This is called in exch_seq_send() when we have a newly allocated
+ * exchange with a valid exchange id to setup ddp.
+ *
+ * returns: none
+ */
+void fc_fcp_ddp_setup(struct fc_fcp_pkt *fsp, u16 xid)
+{
+	struct fc_lport *lp;
+
+	if (!fsp)
+		return;
+
+	lp = fsp->lp;
+	if ((fsp->req_flags & FC_SRB_READ) &&
+	    (lp->lro_enabled) && (lp->tt.ddp_setup)) {
+		if (lp->tt.ddp_setup(lp, xid, scsi_sglist(fsp->cmd),
+				     scsi_sg_count(fsp->cmd)))
+			fsp->xfer_ddp = xid;
+	}
+}
+EXPORT_SYMBOL(fc_fcp_ddp_setup);
+
+/*
+ * fc_fcp_ddp_done - calls to LLD's ddp_done to release any
+ * DDP related resources for this I/O if it is initialized
+ * as a ddp transfer
+ * @fsp: ptr to the fc_fcp_pkt
+ *
+ * returns: none
+ */
+static void fc_fcp_ddp_done(struct fc_fcp_pkt *fsp)
+{
+	struct fc_lport *lp;
+
+	if (!fsp)
+		return;
+
+	lp = fsp->lp;
+	if (fsp->xfer_ddp && lp->tt.ddp_done) {
+		fsp->xfer_len = lp->tt.ddp_done(lp, fsp->xfer_ddp);
+		fsp->xfer_ddp = 0;
+	}
+}
+
+
+/*
  * Receive SCSI data from target.
  * Called after receiving solicited data.
  */
@@ -289,6 +339,9 @@ static void fc_fcp_recv_data(struct fc_fcp_pkt *fsp, struct fc_frame *fp)
 	len = fr_len(fp) - sizeof(*fh);
 	buf = fc_frame_payload_get(fp, 0);
 
+	/* if this I/O is ddped, update xfer len */
+	fc_fcp_ddp_done(fsp);
+
 	if (offset + len > fsp->data_len) {
 		/* this should never happen */
 		if ((fr_flags(fp) & FCPHF_CRC_UNCHECKED) &&
@@ -750,6 +803,9 @@ static void fc_fcp_resp(struct fc_fcp_pkt *fsp, struct fc_frame *fp)
 	fsp->scsi_comp_flags = flags;
 	expected_len = fsp->data_len;
 
+	/* if ddp, update xfer len */
+	fc_fcp_ddp_done(fsp);
+
 	if (unlikely((flags & ~FCP_CONF_REQ) || fc_rp->fr_status)) {
 		rp_ex = (void *)(fc_rp + 1);
 		if (flags & (FCP_RSP_LEN_VAL | FCP_SNS_LEN_VAL)) {
@@ -1012,7 +1068,7 @@ static int fc_fcp_cmd_send(struct fc_lport *lp, struct fc_fcp_pkt *fsp,
 	}
 
 	memcpy(fc_frame_payload_get(fp, len), &fsp->cdb_cmd, len);
-	fr_cmd(fp) = fsp->cmd;
+	fr_fsp(fp) = fsp;
 	rport = fsp->rport;
 	fsp->max_payload = rport->maxframe_size;
 	rp = rport->dd_data;
@@ -1746,6 +1802,9 @@ static void fc_io_compl(struct fc_fcp_pkt *fsp)
 	struct fc_lport *lp;
 	unsigned long flags;
 
+	/* release outstanding ddp context */
+	fc_fcp_ddp_done(fsp);
+
 	fsp->state |= FC_SRB_COMPL;
 	if (!(fsp->state & FC_SRB_FCP_PROCESSING_TMO)) {
 		spin_unlock_bh(&fsp->scsi_pkt_lock);