From 4d9c05f1ee6054f8d9e2162c2026d6da6f0368aa Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bart.vanassche@sandisk.com>
Date: Wed, 14 Oct 2015 22:22:19 +0000
Subject: [PATCH] ib_srpt: Increase maximum sg-list length from 128 to 65536

This avoids that the following message appears in the target system
kernel log:

Unable to complete command due to SG IO count limitation


git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@6545 d57e44dd-8a1f-0410-8b47-8ef2f437770f
---
 srpt/src/ib_srpt.c | 46 +++++++++++++++++++++++++++++++++-------------
 1 file changed, 33 insertions(+), 13 deletions(-)

diff --git a/srpt/src/ib_srpt.c b/srpt/src/ib_srpt.c
index 3a69578a8..7579ea64c 100644
--- a/srpt/src/ib_srpt.c
+++ b/srpt/src/ib_srpt.c
@@ -1449,15 +1449,24 @@ static void srpt_handle_send_err_comp(struct srpt_rdma_ch *ch, u64 wr_id,
 {
 	u32 index = idx_from_wr_id(wr_id);
 	struct srpt_send_ioctx *ioctx = ch->ioctx_ring[index];
+	struct scst_cmd *cmd = &ioctx->cmd;
 	enum srpt_command_state state = ioctx->state;
-
-	srpt_adjust_sq_wr_avail(ch, 1);
+	int wr_avail_delta = 1;
 
 	switch (state) {
 	case SRPT_STATE_NEED_DATA:
 		srpt_abort_cmd(ioctx, context);
 		break;
 	case SRPT_STATE_CMD_RSP_SENT:
+		if (scst_cmd_get_data_direction(cmd) == SCST_DATA_READ) {
+			/*
+			 * IB_SEND_SIGNALED is not set for RDMA writes so
+			 * process the wr_avail delta when the response
+			 * send completion has been received.
+			 */
+			EXTRACHECKS_WARN_ON(ioctx->n_rdma <= 0);
+			wr_avail_delta += ioctx->n_rdma;
+		}
 		srpt_undo_inc_req_lim(ch, ioctx->req_lim_delta);
 		srpt_abort_cmd(ioctx, context);
 		break;
@@ -1473,6 +1482,8 @@ static void srpt_handle_send_err_comp(struct srpt_rdma_ch *ch, u64 wr_id,
 		EXTRACHECKS_WARN_ON(true);
 		break;
 	}
+
+	srpt_adjust_sq_wr_avail(ch, wr_avail_delta);
 }
 
 /**
@@ -1482,10 +1493,20 @@ static void srpt_handle_send_comp(struct srpt_rdma_ch *ch,
 				  struct srpt_send_ioctx *ioctx,
 				  enum scst_exec_context context)
 {
-	srpt_adjust_sq_wr_avail(ch, 1);
+	struct scst_cmd *cmd = &ioctx->cmd;
+	int wr_avail_delta = 1;
 
 	switch (srpt_set_cmd_state(ioctx, SRPT_STATE_DONE)) {
 	case SRPT_STATE_CMD_RSP_SENT:
+		if (scst_cmd_get_data_direction(cmd) == SCST_DATA_READ) {
+			/*
+			 * IB_SEND_SIGNALED is not set for RDMA writes so
+			 * process the wr_avail delta when the response
+			 * send completion has been received.
+			 */
+			EXTRACHECKS_WARN_ON(ioctx->n_rdma <= 0);
+			wr_avail_delta += ioctx->n_rdma;
+		}
 		srpt_unmap_sg_to_ib_sge(ch, ioctx);
 		scst_tgt_cmd_done(&ioctx->cmd, context);
 		break;
@@ -1499,6 +1520,8 @@ static void srpt_handle_send_comp(struct srpt_rdma_ch *ch,
 	default:
 		EXTRACHECKS_WARN_ON(true);
 	}
+
+	srpt_adjust_sq_wr_avail(ch, wr_avail_delta);
 }
 
 /**
@@ -3347,18 +3370,15 @@ static int srpt_perform_rdmas(struct srpt_rdma_ch *ch,
 	struct ib_send_wr *bad_wr;
 	struct rdma_iu *riu;
 	int i;
-	int ret;
+	int ret = -ENOMEM;
 	int sq_wr_avail;
 	const int n_rdma = ioctx->n_rdma;
 
-	if (dir == SCST_DATA_WRITE) {
-		ret = -ENOMEM;
-		sq_wr_avail = srpt_adjust_sq_wr_avail(ch, -n_rdma);
-		if (sq_wr_avail < 0) {
-			pr_warn("ch %s-%d send queue full (needed %d)\n",
-				ch->sess_name, ch->qp->qp_num, n_rdma);
-			goto out;
-		}
+	sq_wr_avail = srpt_adjust_sq_wr_avail(ch, -n_rdma);
+	if (sq_wr_avail < 0) {
+		pr_warn("ch %s-%d send queue full (needed %d)\n",
+			ch->sess_name, ch->qp->qp_num, n_rdma);
+		goto out;
 	}
 
 	ioctx->rdma_aborted = false;
@@ -3421,7 +3441,7 @@ static int srpt_perform_rdmas(struct srpt_rdma_ch *ch,
 	}
 
 out:
-	if (unlikely(dir == SCST_DATA_WRITE && ret < 0))
+	if (unlikely(ret < 0))
 		srpt_adjust_sq_wr_avail(ch, n_rdma);
 	return ret;
 }