RDMA/srpt: Add support for immediate data

Modify allocation of the non-SRQ receive queues such that immediate
data is aligned on a 512 byte boundary. That alignment is necessary
to pass the immediate data without copying to the block layer. When
receiving an SRP_CMD with immediate data, postpone the ib_post_recv()
call until target_execute_cmd() has finished. See also
srpt_release_cmd().

Cc: Sergey Gorenko <sergeygo@mellanox.com>
Cc: Max Gurtovoy <maxg@mellanox.com>
Cc: Laurence Oberman <loberman@redhat.com>
Signed-off-by: NBart Van Assche <bvanassche@acm.org>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/srpt/ib_srpt.c

@@ -648,24 +648,26 @@ static void srpt_unregister_mad_agent(struct srpt_device *sdev)
  * srpt_alloc_ioctx - allocate a SRPT I/O context structure
  * @sdev: SRPT HCA pointer.
  * @ioctx_size: I/O context size.
- * @dma_size: Size of I/O context DMA buffer.
+ * @buf_cache: I/O buffer cache.
  * @dir: DMA data direction.
  */
 static struct srpt_ioctx *srpt_alloc_ioctx(struct srpt_device *sdev,
-					   int ioctx_size, int dma_size,
+					   int ioctx_size,
+					   struct kmem_cache *buf_cache,
 					   enum dma_data_direction dir)
 {
 	struct srpt_ioctx *ioctx;
 
-	ioctx = kmalloc(ioctx_size, GFP_KERNEL);
+	ioctx = kzalloc(ioctx_size, GFP_KERNEL);
 	if (!ioctx)
 		goto err;
 
-	ioctx->buf = kmalloc(dma_size, GFP_KERNEL);
+	ioctx->buf = kmem_cache_alloc(buf_cache, GFP_KERNEL);
 	if (!ioctx->buf)
 		goto err_free_ioctx;
 
-	ioctx->dma = ib_dma_map_single(sdev->device, ioctx->buf, dma_size, dir);
+	ioctx->dma = ib_dma_map_single(sdev->device, ioctx->buf,
+				       kmem_cache_size(buf_cache), dir);
 	if (ib_dma_mapping_error(sdev->device, ioctx->dma))
 		goto err_free_buf;
 
@@ -683,17 +685,19 @@ static struct srpt_ioctx *srpt_alloc_ioctx(struct srpt_device *sdev,
  * srpt_free_ioctx - free a SRPT I/O context structure
  * @sdev: SRPT HCA pointer.
  * @ioctx: I/O context pointer.
- * @dma_size: Size of I/O context DMA buffer.
+ * @buf_cache: I/O buffer cache.
  * @dir: DMA data direction.
  */
 static void srpt_free_ioctx(struct srpt_device *sdev, struct srpt_ioctx *ioctx,
-			    int dma_size, enum dma_data_direction dir)
+			    struct kmem_cache *buf_cache,
+			    enum dma_data_direction dir)
 {
 	if (!ioctx)
 		return;
 
-	ib_dma_unmap_single(sdev->device, ioctx->dma, dma_size, dir);
-	kfree(ioctx->buf);
+	ib_dma_unmap_single(sdev->device, ioctx->dma,
+			    kmem_cache_size(buf_cache), dir);
+	kmem_cache_free(buf_cache, ioctx->buf);
 	kfree(ioctx);
 }
 
@@ -702,12 +706,16 @@ static void srpt_free_ioctx(struct srpt_device *sdev, struct srpt_ioctx *ioctx,
  * @sdev:       Device to allocate the I/O context ring for.
  * @ring_size:  Number of elements in the I/O context ring.
  * @ioctx_size: I/O context size.
- * @dma_size:   DMA buffer size.
+ * @buf_cache:  I/O buffer cache.
+ * @alignment_offset: Offset in each ring buffer at which the SRP information
+ *		unit starts.
  * @dir:        DMA data direction.
  */
 static struct srpt_ioctx **srpt_alloc_ioctx_ring(struct srpt_device *sdev,
 				int ring_size, int ioctx_size,
-				int dma_size, enum dma_data_direction dir)
+				struct kmem_cache *buf_cache,
+				int alignment_offset,
+				enum dma_data_direction dir)
 {
 	struct srpt_ioctx **ring;
 	int i;
@@ -719,16 +727,17 @@ static struct srpt_ioctx **srpt_alloc_ioctx_ring(struct srpt_device *sdev,
 	if (!ring)
 		goto out;
 	for (i = 0; i < ring_size; ++i) {
-		ring[i] = srpt_alloc_ioctx(sdev, ioctx_size, dma_size, dir);
+		ring[i] = srpt_alloc_ioctx(sdev, ioctx_size, buf_cache, dir);
 		if (!ring[i])
 			goto err;
 		ring[i]->index = i;
+		ring[i]->offset = alignment_offset;
 	}
 	goto out;
 
 err:
 	while (--i >= 0)
-		srpt_free_ioctx(sdev, ring[i], dma_size, dir);
+		srpt_free_ioctx(sdev, ring[i], buf_cache, dir);
 	kvfree(ring);
 	ring = NULL;
 out:
@@ -740,12 +749,13 @@ static struct srpt_ioctx **srpt_alloc_ioctx_ring(struct srpt_device *sdev,
  * @ioctx_ring: I/O context ring to be freed.
  * @sdev: SRPT HCA pointer.
  * @ring_size: Number of ring elements.
- * @dma_size: Size of I/O context DMA buffer.
+ * @buf_cache: I/O buffer cache.
  * @dir: DMA data direction.
  */
 static void srpt_free_ioctx_ring(struct srpt_ioctx **ioctx_ring,
 				 struct srpt_device *sdev, int ring_size,
-				 int dma_size, enum dma_data_direction dir)
+				 struct kmem_cache *buf_cache,
+				 enum dma_data_direction dir)
 {
 	int i;
 
@@ -753,7 +763,7 @@ static void srpt_free_ioctx_ring(struct srpt_ioctx **ioctx_ring,
 		return;
 
 	for (i = 0; i < ring_size; ++i)
-		srpt_free_ioctx(sdev, ioctx_ring[i], dma_size, dir);
+		srpt_free_ioctx(sdev, ioctx_ring[i], buf_cache, dir);
 	kvfree(ioctx_ring);
 }
 
@@ -815,7 +825,7 @@ static int srpt_post_recv(struct srpt_device *sdev, struct srpt_rdma_ch *ch,
 	struct ib_recv_wr wr;
 
 	BUG_ON(!sdev);
-	list.addr = ioctx->ioctx.dma;
+	list.addr = ioctx->ioctx.dma + ioctx->ioctx.offset;
 	list.length = srp_max_req_size;
 	list.lkey = sdev->lkey;
 
@@ -981,23 +991,28 @@ static inline void *srpt_get_desc_buf(struct srp_cmd *srp_cmd)
 
 /**
  * srpt_get_desc_tbl - parse the data descriptors of a SRP_CMD request
- * @ioctx: Pointer to the I/O context associated with the request.
+ * @recv_ioctx: I/O context associated with the received command @srp_cmd.
+ * @ioctx: I/O context that will be used for responding to the initiator.
  * @srp_cmd: Pointer to the SRP_CMD request data.
  * @dir: Pointer to the variable to which the transfer direction will be
  *   written.
- * @sg: [out] scatterlist allocated for the parsed SRP_CMD.
+ * @sg: [out] scatterlist for the parsed SRP_CMD.
  * @sg_cnt: [out] length of @sg.
  * @data_len: Pointer to the variable to which the total data length of all
  *   descriptors in the SRP_CMD request will be written.
+ * @imm_data_offset: [in] Offset in SRP_CMD requests at which immediate data
+ *   starts.
  *
  * This function initializes ioctx->nrbuf and ioctx->r_bufs.
  *
  * Returns -EINVAL when the SRP_CMD request contains inconsistent descriptors;
  * -ENOMEM when memory allocation fails and zero upon success.
  */
-static int srpt_get_desc_tbl(struct srpt_send_ioctx *ioctx,
+static int srpt_get_desc_tbl(struct srpt_recv_ioctx *recv_ioctx,
+		struct srpt_send_ioctx *ioctx,
 		struct srp_cmd *srp_cmd, enum dma_data_direction *dir,
-		struct scatterlist **sg, unsigned *sg_cnt, u64 *data_len)
+		struct scatterlist **sg, unsigned int *sg_cnt, u64 *data_len,
+		u16 imm_data_offset)
 {
 	BUG_ON(!dir);
 	BUG_ON(!data_len);
@@ -1044,6 +1059,40 @@ static int srpt_get_desc_tbl(struct srpt_send_ioctx *ioctx,
 		*data_len = be32_to_cpu(idb->len);
 		return srpt_alloc_rw_ctxs(ioctx, idb->desc_list, nbufs,
 				sg, sg_cnt);
+	} else if ((srp_cmd->buf_fmt >> 4) == SRP_DATA_DESC_IMM) {
+		struct srp_imm_buf *imm_buf = srpt_get_desc_buf(srp_cmd);
+		void *data = (void *)srp_cmd + imm_data_offset;
+		uint32_t len = be32_to_cpu(imm_buf->len);
+		uint32_t req_size = imm_data_offset + len;
+
+		if (req_size > srp_max_req_size) {
+			pr_err("Immediate data (length %d + %d) exceeds request size %d\n",
+			       imm_data_offset, len, srp_max_req_size);
+			return -EINVAL;
+		}
+		if (recv_ioctx->byte_len < req_size) {
+			pr_err("Received too few data - %d < %d\n",
+			       recv_ioctx->byte_len, req_size);
+			return -EIO;
+		}
+		/*
+		 * The immediate data buffer descriptor must occur before the
+		 * immediate data itself.
+		 */
+		if ((void *)(imm_buf + 1) > (void *)data) {
+			pr_err("Received invalid write request\n");
+			return -EINVAL;
+		}
+		*data_len = len;
+		ioctx->recv_ioctx = recv_ioctx;
+		if ((uintptr_t)data & 511) {
+			pr_warn_once("Internal error - the receive buffers are not aligned properly.\n");
+			return -EINVAL;
+		}
+		sg_init_one(&ioctx->imm_sg, data, len);
+		*sg = &ioctx->imm_sg;
+		*sg_cnt = 1;
+		return 0;
 	} else {
 		*data_len = 0;
 		return 0;
@@ -1186,6 +1235,7 @@ static struct srpt_send_ioctx *srpt_get_send_ioctx(struct srpt_rdma_ch *ch)
 
 	BUG_ON(ioctx->ch != ch);
 	ioctx->state = SRPT_STATE_NEW;
+	WARN_ON_ONCE(ioctx->recv_ioctx);
 	ioctx->n_rdma = 0;
 	ioctx->n_rw_ctx = 0;
 	ioctx->queue_status_only = false;
@@ -1428,7 +1478,7 @@ static void srpt_handle_cmd(struct srpt_rdma_ch *ch,
 
 	BUG_ON(!send_ioctx);
 
-	srp_cmd = recv_ioctx->ioctx.buf;
+	srp_cmd = recv_ioctx->ioctx.buf + recv_ioctx->ioctx.offset;
 	cmd = &send_ioctx->cmd;
 	cmd->tag = srp_cmd->tag;
 
@@ -1448,8 +1498,8 @@ static void srpt_handle_cmd(struct srpt_rdma_ch *ch,
 		break;
 	}
 
-	rc = srpt_get_desc_tbl(send_ioctx, srp_cmd, &dir, &sg, &sg_cnt,
-			&data_len);
+	rc = srpt_get_desc_tbl(recv_ioctx, send_ioctx, srp_cmd, &dir,
+			       &sg, &sg_cnt, &data_len, ch->imm_data_offset);
 	if (rc) {
 		if (rc != -EAGAIN) {
 			pr_err("0x%llx: parsing SRP descriptor table failed.\n",
@@ -1516,7 +1566,7 @@ static void srpt_handle_tsk_mgmt(struct srpt_rdma_ch *ch,
 
 	BUG_ON(!send_ioctx);
 
-	srp_tsk = recv_ioctx->ioctx.buf;
+	srp_tsk = recv_ioctx->ioctx.buf + recv_ioctx->ioctx.offset;
 	cmd = &send_ioctx->cmd;
 
 	pr_debug("recv tsk_mgmt fn %d for task_tag %lld and cmd tag %lld ch %p sess %p\n",
@@ -1559,10 +1609,11 @@ srpt_handle_new_iu(struct srpt_rdma_ch *ch, struct srpt_recv_ioctx *recv_ioctx)
 		goto push;
 
 	ib_dma_sync_single_for_cpu(ch->sport->sdev->device,
-				   recv_ioctx->ioctx.dma, srp_max_req_size,
+				   recv_ioctx->ioctx.dma,
+				   recv_ioctx->ioctx.offset + srp_max_req_size,
 				   DMA_FROM_DEVICE);
 
-	srp_cmd = recv_ioctx->ioctx.buf;
+	srp_cmd = recv_ioctx->ioctx.buf + recv_ioctx->ioctx.offset;
 	opcode = srp_cmd->opcode;
 	if (opcode == SRP_CMD || opcode == SRP_TSK_MGMT) {
 		send_ioctx = srpt_get_send_ioctx(ch);
@@ -1599,7 +1650,8 @@ srpt_handle_new_iu(struct srpt_rdma_ch *ch, struct srpt_recv_ioctx *recv_ioctx)
 		break;
 	}
 
-	srpt_post_recv(ch->sport->sdev, ch, recv_ioctx);
+	if (!send_ioctx || !send_ioctx->recv_ioctx)
+		srpt_post_recv(ch->sport->sdev, ch, recv_ioctx);
 	res = true;
 
 out:
@@ -1625,6 +1677,7 @@ static void srpt_recv_done(struct ib_cq *cq, struct ib_wc *wc)
 		req_lim = atomic_dec_return(&ch->req_lim);
 		if (unlikely(req_lim < 0))
 			pr_err("req_lim = %d < 0\n", req_lim);
+		ioctx->byte_len = wc->byte_len;
 		srpt_handle_new_iu(ch, ioctx);
 	} else {
 		pr_info_ratelimited("receiving failed for ioctx %p with status %d\n",
@@ -1749,6 +1802,8 @@ static int srpt_create_ch_ib(struct srpt_rdma_ch *ch)
 	qp_init->cap.max_rdma_ctxs = sq_size / 2;
 	qp_init->cap.max_send_sge = min(attrs->max_send_sge,
 					SRPT_MAX_SG_PER_WQE);
+	qp_init->cap.max_recv_sge = min(attrs->max_recv_sge,
+					SRPT_MAX_SG_PER_WQE);
 	qp_init->port_num = ch->sport->port;
 	if (sdev->use_srq) {
 		qp_init->srq = sdev->srq;
@@ -2049,11 +2104,15 @@ static void srpt_release_channel_work(struct work_struct *w)
 
 	srpt_free_ioctx_ring((struct srpt_ioctx **)ch->ioctx_ring,
 			     ch->sport->sdev, ch->rq_size,
-			     ch->max_rsp_size, DMA_TO_DEVICE);
+			     ch->rsp_buf_cache, DMA_TO_DEVICE);
+
+	kmem_cache_destroy(ch->rsp_buf_cache);
 
 	srpt_free_ioctx_ring((struct srpt_ioctx **)ch->ioctx_recv_ring,
 			     sdev, ch->rq_size,
-			     srp_max_req_size, DMA_FROM_DEVICE);
+			     ch->req_buf_cache, DMA_FROM_DEVICE);
+
+	kmem_cache_destroy(ch->req_buf_cache);
 
 	wake_up(&sport->ch_releaseQ);
 
@@ -2177,14 +2236,19 @@ static int srpt_cm_req_recv(struct srpt_device *const sdev,
 	INIT_LIST_HEAD(&ch->cmd_wait_list);
 	ch->max_rsp_size = ch->sport->port_attrib.srp_max_rsp_size;
 
+	ch->rsp_buf_cache = kmem_cache_create("srpt-rsp-buf", ch->max_rsp_size,
+					      512, 0, NULL);
+	if (!ch->rsp_buf_cache)
+		goto free_ch;
+
 	ch->ioctx_ring = (struct srpt_send_ioctx **)
 		srpt_alloc_ioctx_ring(ch->sport->sdev, ch->rq_size,
 				      sizeof(*ch->ioctx_ring[0]),
-				      ch->max_rsp_size, DMA_TO_DEVICE);
+				      ch->rsp_buf_cache, 0, DMA_TO_DEVICE);
 	if (!ch->ioctx_ring) {
 		pr_err("rejected SRP_LOGIN_REQ because creating a new QP SQ ring failed.\n");
 		rej->reason = cpu_to_be32(SRP_LOGIN_REJ_INSUFFICIENT_RESOURCES);
-		goto free_ch;
+		goto free_rsp_cache;
 	}
 
 	INIT_LIST_HEAD(&ch->free_list);
@@ -2193,16 +2257,39 @@ static int srpt_cm_req_recv(struct srpt_device *const sdev,
 		list_add_tail(&ch->ioctx_ring[i]->free_list, &ch->free_list);
 	}
 	if (!sdev->use_srq) {
+		u16 imm_data_offset = req->req_flags & SRP_IMMED_REQUESTED ?
+			be16_to_cpu(req->imm_data_offset) : 0;
+		u16 alignment_offset;
+		u32 req_sz;
+
+		if (req->req_flags & SRP_IMMED_REQUESTED)
+			pr_debug("imm_data_offset = %d\n",
+				 be16_to_cpu(req->imm_data_offset));
+		if (imm_data_offset >= sizeof(struct srp_cmd)) {
+			ch->imm_data_offset = imm_data_offset;
+			rsp->rsp_flags |= SRP_LOGIN_RSP_IMMED_SUPP;
+		} else {
+			ch->imm_data_offset = 0;
+		}
+		alignment_offset = round_up(imm_data_offset, 512) -
+			imm_data_offset;
+		req_sz = alignment_offset + imm_data_offset + srp_max_req_size;
+		ch->req_buf_cache = kmem_cache_create("srpt-req-buf", req_sz,
+						      512, 0, NULL);
+		if (!ch->req_buf_cache)
+			goto free_rsp_ring;
+
 		ch->ioctx_recv_ring = (struct srpt_recv_ioctx **)
 			srpt_alloc_ioctx_ring(ch->sport->sdev, ch->rq_size,
 					      sizeof(*ch->ioctx_recv_ring[0]),
-					      srp_max_req_size,
+					      ch->req_buf_cache,
+					      alignment_offset,
 					      DMA_FROM_DEVICE);
 		if (!ch->ioctx_recv_ring) {
 			pr_err("rejected SRP_LOGIN_REQ because creating a new QP RQ ring failed.\n");
 			rej->reason =
 			    cpu_to_be32(SRP_LOGIN_REJ_INSUFFICIENT_RESOURCES);
-			goto free_ring;
+			goto free_recv_cache;
 		}
 		for (i = 0; i < ch->rq_size; i++)
 			INIT_LIST_HEAD(&ch->ioctx_recv_ring[i]->wait_list);
@@ -2252,17 +2339,15 @@ static int srpt_cm_req_recv(struct srpt_device *const sdev,
 	if ((req->req_flags & SRP_MTCH_ACTION) == SRP_MULTICHAN_SINGLE) {
 		struct srpt_rdma_ch *ch2;
 
-		rsp->rsp_flags = SRP_LOGIN_RSP_MULTICHAN_NO_CHAN;
-
 		list_for_each_entry(ch2, &nexus->ch_list, list) {
 			if (srpt_disconnect_ch(ch2) < 0)
 				continue;
 			pr_info("Relogin - closed existing channel %s\n",
 				ch2->sess_name);
-			rsp->rsp_flags = SRP_LOGIN_RSP_MULTICHAN_TERMINATED;
+			rsp->rsp_flags |= SRP_LOGIN_RSP_MULTICHAN_TERMINATED;
 		}
 	} else {
-		rsp->rsp_flags = SRP_LOGIN_RSP_MULTICHAN_MAINTAINED;
+		rsp->rsp_flags |= SRP_LOGIN_RSP_MULTICHAN_MAINTAINED;
 	}
 
 	list_add_tail_rcu(&ch->list, &nexus->ch_list);
@@ -2292,7 +2377,7 @@ static int srpt_cm_req_recv(struct srpt_device *const sdev,
 	/* create srp_login_response */
 	rsp->opcode = SRP_LOGIN_RSP;
 	rsp->tag = req->tag;
-	rsp->max_it_iu_len = req->req_it_iu_len;
+	rsp->max_it_iu_len = cpu_to_be32(srp_max_req_size);
 	rsp->max_ti_iu_len = req->req_it_iu_len;
 	ch->max_ti_iu_len = it_iu_len;
 	rsp->buf_fmt = cpu_to_be16(SRP_BUF_FORMAT_DIRECT |
@@ -2356,12 +2441,18 @@ static int srpt_cm_req_recv(struct srpt_device *const sdev,
 free_recv_ring:
 	srpt_free_ioctx_ring((struct srpt_ioctx **)ch->ioctx_recv_ring,
 			     ch->sport->sdev, ch->rq_size,
-			     srp_max_req_size, DMA_FROM_DEVICE);
+			     ch->req_buf_cache, DMA_FROM_DEVICE);
 
-free_ring:
+free_recv_cache:
+	kmem_cache_destroy(ch->req_buf_cache);
+
+free_rsp_ring:
 	srpt_free_ioctx_ring((struct srpt_ioctx **)ch->ioctx_ring,
 			     ch->sport->sdev, ch->rq_size,
-			     ch->max_rsp_size, DMA_TO_DEVICE);
+			     ch->rsp_buf_cache, DMA_TO_DEVICE);
+
+free_rsp_cache:
+	kmem_cache_destroy(ch->rsp_buf_cache);
 
 free_ch:
 	if (rdma_cm_id)
@@ -2442,6 +2533,7 @@ static int srpt_rdma_cm_req_recv(struct rdma_cm_id *cm_id,
 	req.req_flags		= req_rdma->req_flags;
 	memcpy(req.initiator_port_id, req_rdma->initiator_port_id, 16);
 	memcpy(req.target_port_id, req_rdma->target_port_id, 16);
+	req.imm_data_offset	= req_rdma->imm_data_offset;
 
 	snprintf(src_addr, sizeof(src_addr), "%pIS",
 		 &cm_id->route.addr.src_addr);
@@ -2632,6 +2724,12 @@ static int srpt_write_pending(struct se_cmd *se_cmd)
 	enum srpt_command_state new_state;
 	int ret, i;
 
+	if (ioctx->recv_ioctx) {
+		srpt_set_cmd_state(ioctx, SRPT_STATE_DATA_IN);
+		target_execute_cmd(&ioctx->cmd);
+		return 0;
+	}
+
 	new_state = srpt_set_cmd_state(ioctx, SRPT_STATE_NEED_DATA);
 	WARN_ON(new_state == SRPT_STATE_DONE);
 
@@ -2911,7 +3009,9 @@ static void srpt_free_srq(struct srpt_device *sdev)
 
 	ib_destroy_srq(sdev->srq);
 	srpt_free_ioctx_ring((struct srpt_ioctx **)sdev->ioctx_ring, sdev,
-			     sdev->srq_size, srp_max_req_size, DMA_FROM_DEVICE);
+			     sdev->srq_size, sdev->req_buf_cache,
+			     DMA_FROM_DEVICE);
+	kmem_cache_destroy(sdev->req_buf_cache);
 	sdev->srq = NULL;
 }
 
@@ -2938,12 +3038,17 @@ static int srpt_alloc_srq(struct srpt_device *sdev)
 	pr_debug("create SRQ #wr= %d max_allow=%d dev= %s\n", sdev->srq_size,
 		 sdev->device->attrs.max_srq_wr, dev_name(&device->dev));
 
+	sdev->req_buf_cache = kmem_cache_create("srpt-srq-req-buf",
+						srp_max_req_size, 0, 0, NULL);
+	if (!sdev->req_buf_cache)
+		goto free_srq;
+
 	sdev->ioctx_ring = (struct srpt_recv_ioctx **)
 		srpt_alloc_ioctx_ring(sdev, sdev->srq_size,
 				      sizeof(*sdev->ioctx_ring[0]),
-				      srp_max_req_size, DMA_FROM_DEVICE);
+				      sdev->req_buf_cache, 0, DMA_FROM_DEVICE);
 	if (!sdev->ioctx_ring)
-		goto free_srq;
+		goto free_cache;
 
 	sdev->use_srq = true;
 	sdev->srq = srq;
@@ -2955,6 +3060,9 @@ static int srpt_alloc_srq(struct srpt_device *sdev)
 
 	return 0;
 
+free_cache:
+	kmem_cache_destroy(sdev->req_buf_cache);
+
 free_srq:
 	ib_destroy_srq(srq);
 	return -ENOMEM;
@@ -3186,11 +3294,18 @@ static void srpt_release_cmd(struct se_cmd *se_cmd)
 	struct srpt_send_ioctx *ioctx = container_of(se_cmd,
 				struct srpt_send_ioctx, cmd);
 	struct srpt_rdma_ch *ch = ioctx->ch;
+	struct srpt_recv_ioctx *recv_ioctx = ioctx->recv_ioctx;
 	unsigned long flags;
 
 	WARN_ON_ONCE(ioctx->state != SRPT_STATE_DONE &&
 		     !(ioctx->cmd.transport_state & CMD_T_ABORTED));
 
+	if (recv_ioctx) {
+		WARN_ON_ONCE(!list_empty(&recv_ioctx->wait_list));
+		ioctx->recv_ioctx = NULL;
+		srpt_post_recv(ch->sport->sdev, ch, recv_ioctx);
+	}
+
 	if (ioctx->n_rw_ctx) {
 		srpt_free_rw_ctxs(ch, ioctx);
 		ioctx->n_rw_ctx = 0;

drivers/infiniband/ulp/srpt/ib_srpt.h

@@ -120,11 +120,18 @@ enum {
 	MAX_SRPT_RDMA_SIZE = 1U << 24,
 	MAX_SRPT_RSP_SIZE = 1024,
 
+	SRP_MAX_ADD_CDB_LEN = 16,
+	SRP_MAX_IMM_DATA_OFFSET = 80,
+	SRP_MAX_IMM_DATA = 8 * 1024,
 	MIN_MAX_REQ_SIZE = 996,
-	DEFAULT_MAX_REQ_SIZE
-		= sizeof(struct srp_cmd)/*48*/
-		+ sizeof(struct srp_indirect_buf)/*20*/
-		+ 128 * sizeof(struct srp_direct_buf)/*16*/,
+	DEFAULT_MAX_REQ_SIZE_1 = sizeof(struct srp_cmd)/*48*/ +
+				 SRP_MAX_ADD_CDB_LEN +
+				 sizeof(struct srp_indirect_buf)/*20*/ +
+				 128 * sizeof(struct srp_direct_buf)/*16*/,
+	DEFAULT_MAX_REQ_SIZE_2 = SRP_MAX_IMM_DATA_OFFSET +
+				 sizeof(struct srp_imm_buf) + SRP_MAX_IMM_DATA,
+	DEFAULT_MAX_REQ_SIZE = DEFAULT_MAX_REQ_SIZE_1 > DEFAULT_MAX_REQ_SIZE_2 ?
+			       DEFAULT_MAX_REQ_SIZE_1 : DEFAULT_MAX_REQ_SIZE_2,
 
 	MIN_MAX_RSP_SIZE = sizeof(struct srp_rsp)/*36*/ + 4,
 	DEFAULT_MAX_RSP_SIZE = 256, /* leaves 220 bytes for sense data */
@@ -161,12 +168,14 @@ enum srpt_command_state {
  * @cqe:   Completion queue element.
  * @buf:   Pointer to the buffer.
  * @dma:   DMA address of the buffer.
+ * @offset: Offset of the first byte in @buf and @dma that is actually used.
  * @index: Index of the I/O context in its ioctx_ring array.
  */
 struct srpt_ioctx {
 	struct ib_cqe		cqe;
 	void			*buf;
 	dma_addr_t		dma;
+	uint32_t		offset;
 	uint32_t		index;
 };
 
@@ -174,10 +183,12 @@ struct srpt_ioctx {
  * struct srpt_recv_ioctx - SRPT receive I/O context
  * @ioctx:     See above.
  * @wait_list: Node for insertion in srpt_rdma_ch.cmd_wait_list.
+ * @byte_len:  Number of bytes in @ioctx.buf.
  */
 struct srpt_recv_ioctx {
 	struct srpt_ioctx	ioctx;
 	struct list_head	wait_list;
+	int			byte_len;
 };
 
 struct srpt_rw_ctx {
@@ -190,8 +201,11 @@ struct srpt_rw_ctx {
  * struct srpt_send_ioctx - SRPT send I/O context
  * @ioctx:       See above.
  * @ch:          Channel pointer.
+ * @recv_ioctx:  Receive I/O context associated with this send I/O context.
+ *		 Only used for processing immediate data.
  * @s_rw_ctx:    @rw_ctxs points here if only a single rw_ctx is needed.
  * @rw_ctxs:     RDMA read/write contexts.
+ * @imm_sg:      Scatterlist for immediate data.
  * @rdma_cqe:    RDMA completion queue element.
  * @free_list:   Node in srpt_rdma_ch.free_list.
  * @state:       I/O context state.
@@ -205,10 +219,13 @@ struct srpt_rw_ctx {
 struct srpt_send_ioctx {
 	struct srpt_ioctx	ioctx;
 	struct srpt_rdma_ch	*ch;
+	struct srpt_recv_ioctx	*recv_ioctx;
 
 	struct srpt_rw_ctx	s_rw_ctx;
 	struct srpt_rw_ctx	*rw_ctxs;
 
+	struct scatterlist	imm_sg;
+
 	struct ib_cqe		rdma_cqe;
 	struct list_head	free_list;
 	enum srpt_command_state	state;
@@ -258,12 +275,15 @@ enum rdma_ch_state {
  * @req_lim:       request limit: maximum number of requests that may be sent
  *                 by the initiator without having received a response.
  * @req_lim_delta: Number of credits not yet sent back to the initiator.
+ * @imm_data_offset: Offset from start of SRP_CMD for immediate data.
  * @spinlock:      Protects free_list and state.
  * @free_list:     Head of list with free send I/O contexts.
  * @state:         channel state. See also enum rdma_ch_state.
  * @using_rdma_cm: Whether the RDMA/CM or IB/CM is used for this channel.
  * @processing_wait_list: Whether or not cmd_wait_list is being processed.
+ * @rsp_buf_cache: kmem_cache for @ioctx_ring.
  * @ioctx_ring:    Send ring.
+ * @req_buf_cache: kmem_cache for @ioctx_recv_ring.
  * @ioctx_recv_ring: Receive I/O context ring.
  * @list:          Node in srpt_nexus.ch_list.
  * @cmd_wait_list: List of SCSI commands that arrived before the RTU event. This
@@ -296,10 +316,13 @@ struct srpt_rdma_ch {
 	int			max_ti_iu_len;
 	atomic_t		req_lim;
 	atomic_t		req_lim_delta;
+	u16			imm_data_offset;
 	spinlock_t		spinlock;
 	struct list_head	free_list;
 	enum rdma_ch_state	state;
+	struct kmem_cache	*rsp_buf_cache;
 	struct srpt_send_ioctx	**ioctx_ring;
+	struct kmem_cache	*req_buf_cache;
 	struct srpt_recv_ioctx	**ioctx_recv_ring;
 	struct list_head	list;
 	struct list_head	cmd_wait_list;
@@ -394,6 +417,7 @@ struct srpt_port {
  * @srq_size:      SRQ size.
  * @sdev_mutex:	   Serializes use_srq changes.
  * @use_srq:       Whether or not to use SRQ.
+ * @req_buf_cache: kmem_cache for @ioctx_ring buffers.
  * @ioctx_ring:    Per-HCA SRQ.
  * @event_handler: Per-HCA asynchronous IB event handler.
  * @list:          Node in srpt_dev_list.
@@ -408,6 +432,7 @@ struct srpt_device {
 	int			srq_size;
 	struct mutex		sdev_mutex;
 	bool			use_srq;
+	struct kmem_cache	*req_buf_cache;
 	struct srpt_recv_ioctx	**ioctx_ring;
 	struct ib_event_handler	event_handler;
 	struct list_head	list;