svcrdma: refactor marshalling logic

From: Tom Tucker <[email protected]>

Change poll logic to grab up to 6 completions at a time.

RDMA write and send completions no longer deal with fastreg objects.

Set SVCRDMA_DEVCAP_FAST_REG and allocate a dma_mr based on the device capabilities.

Signed-off-by Tom Tucker <[email protected]>

Signed-off-by Steve Wise <[email protected]>

---

 include/linux/sunrpc/svc_rdma.h          |    3 -
 net/sunrpc/xprtrdma/svc_rdma_transport.c |   62 +++++++++++++++++-------------
 2 files changed, 37 insertions(+), 28 deletions(-)

include/linux/sunrpc/svc_rdma.h +1 -2

index 0b8e3e6..5cf99a0 100644
@@ -115,14 +115,13 @@ struct svc_rdma_fastreg_mr {
 	struct list_head frmr_list;
 };
 struct svc_rdma_req_map {
-	struct svc_rdma_fastreg_mr *frmr;
 	unsigned long count;
 	union {
 		struct kvec sge[RPCSVC_MAXPAGES];
 		struct svc_rdma_chunk_sge ch[RPCSVC_MAXPAGES];
+		unsigned long lkey[RPCSVC_MAXPAGES];
 	};
 };
-#define RDMACTXT_F_FAST_UNREG	1
 #define RDMACTXT_F_LAST_CTXT	2
 
 #define	SVCRDMA_DEVCAP_FAST_REG		1	/* fast mr registration */

net/sunrpc/xprtrdma/svc_rdma_transport.c +4 -5

index 25688fa..2c5b201 100644
@@ -1,4 +1,5 @@
 /*
+ * Copyright (c) 2014 Open Grid Computing, Inc. All rights reserved.
  * Copyright (c) 2005-2007 Network Appliance, Inc. All rights reserved.
  *
  * This software is available to you under a choice of one of two

@@ -160,7 +161,6 @@ struct svc_rdma_req_map *svc_rdma_get_req_map(void)
 		schedule_timeout_uninterruptible(msecs_to_jiffies(500));
 	}
 	map->count = 0;
-	map->frmr = NULL;
 	return map;
 }
 

@@ -336,22 +336,21 @@ static void process_context(struct svcxprt_rdma *xprt,
 
 	switch (ctxt->wr_op) {
 	case IB_WR_SEND:
-		if (test_bit(RDMACTXT_F_FAST_UNREG, &ctxt->flags))
-			svc_rdma_put_frmr(xprt, ctxt->frmr);
+		BUG_ON(ctxt->frmr);
 		svc_rdma_put_context(ctxt, 1);
 		break;
 
 	case IB_WR_RDMA_WRITE:
+		BUG_ON(ctxt->frmr);
 		svc_rdma_put_context(ctxt, 0);
 		break;
 
 	case IB_WR_RDMA_READ:
 	case IB_WR_RDMA_READ_WITH_INV:
+		svc_rdma_put_frmr(xprt, ctxt->frmr);
 		if (test_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags)) {
 			struct svc_rdma_op_ctxt *read_hdr = ctxt->read_hdr;
 			BUG_ON(!read_hdr);
-			if (test_bit(RDMACTXT_F_FAST_UNREG, &ctxt->flags))
-				svc_rdma_put_frmr(xprt, ctxt->frmr);
 			spin_lock_bh(&xprt->sc_rq_dto_lock);
 			set_bit(XPT_DATA, &xprt->sc_xprt.xpt_flags);
 			list_add_tail(&read_hdr->dto_q,

net/sunrpc/xprtrdma/svc_rdma_transport.c +28 -14

+	memset(wc_a, 0, sizeof(wc_a));
+
 	if (!test_and_clear_bit(RDMAXPRT_SQ_PENDING, &xprt->sc_flags))
 		return;
 
 	ib_req_notify_cq(xprt->sc_sq_cq, IB_CQ_NEXT_COMP);
 	atomic_inc(&rdma_stat_sq_poll);
-	while ((ret = ib_poll_cq(cq, 1, &wc)) > 0) {
-		if (wc.status != IB_WC_SUCCESS)
-			/* Close the transport */
-			set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
+	while ((ret = ib_poll_cq(cq, ARRAY_SIZE(wc_a), wc_a)) > 0) {
+		int i;
 
-		/* Decrement used SQ WR count */
-		atomic_dec(&xprt->sc_sq_count);
-		wake_up(&xprt->sc_send_wait);
+		for (i = 0; i < ret; i++) {
+			wc = &wc_a[i];
+			if (wc->status != IB_WC_SUCCESS) {
+				dprintk("svcrdma: sq wc err status %d\n",
+					wc->status);
 
-		ctxt = (struct svc_rdma_op_ctxt *)(unsigned long)wc.wr_id;
-		if (ctxt)
-			process_context(xprt, ctxt);
+				/* Close the transport */
+				set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
+			}
 
-		svc_xprt_put(&xprt->sc_xprt);
+			/* Decrement used SQ WR count */
+			atomic_dec(&xprt->sc_sq_count);
+			wake_up(&xprt->sc_send_wait);
+
+			ctxt = (struct svc_rdma_op_ctxt *)
+				(unsigned long)wc->wr_id;
+			if (ctxt)
+				process_context(xprt, ctxt);
+
+			svc_xprt_put(&xprt->sc_xprt);
+		}
 	}
 
 	if (ctxt)

@@ -993,7 +1006,11 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 			need_dma_mr = 0;
 		break;
 	case RDMA_TRANSPORT_IB:
-		if (!(devattr.device_cap_flags & IB_DEVICE_LOCAL_DMA_LKEY)) {
+		if (!(newxprt->sc_dev_caps & SVCRDMA_DEVCAP_FAST_REG)) {
+			need_dma_mr = 1;
+			dma_mr_acc = IB_ACCESS_LOCAL_WRITE;
+		} else if (!(devattr.device_cap_flags &
+			     IB_DEVICE_LOCAL_DMA_LKEY)) {
 			need_dma_mr = 1;
 			dma_mr_acc = IB_ACCESS_LOCAL_WRITE;
 		} else

@@ -1190,14 +1207,7 @@ static int svc_rdma_has_wspace(struct svc_xprt *xprt)
 		container_of(xprt, struct svcxprt_rdma, sc_xprt);
 
 	/*
-	 * If there are fewer SQ WR available than required to send a
-	 * simple response, return false.

Quoted 84 lines · Steve Wise

From: Tom Tucker <[email protected]>

Change poll logic to grab up to 6 completions at a time.

RDMA write and send completions no longer deal with fastreg objects.

Set SVCRDMA_DEVCAP_FAST_REG and allocate a dma_mr based on the device capabilities.

Signed-off-by Tom Tucker <[email protected]>

Signed-off-by Steve Wise <[email protected]>

---

  include/linux/sunrpc/svc_rdma.h          |    3 -
  net/sunrpc/xprtrdma/svc_rdma_transport.c |   62 +++++++++++++++++-------------
  2 files changed, 37 insertions(+), 28 deletions(-)

include/linux/sunrpc/svc_rdma.h +1 -2

index 0b8e3e6..5cf99a0 100644
@@ -115,14 +115,13 @@ struct svc_rdma_fastreg_mr {
  	struct list_head frmr_list;
  };
  struct svc_rdma_req_map {
-	struct svc_rdma_fastreg_mr *frmr;
  	unsigned long count;
  	union {
  		struct kvec sge[RPCSVC_MAXPAGES];
  		struct svc_rdma_chunk_sge ch[RPCSVC_MAXPAGES];
+		unsigned long lkey[RPCSVC_MAXPAGES];
  	};
  };
-#define RDMACTXT_F_FAST_UNREG	1
  #define RDMACTXT_F_LAST_CTXT	2
 
  #define	SVCRDMA_DEVCAP_FAST_REG		1	/* fast mr registration */

net/sunrpc/xprtrdma/svc_rdma_transport.c +4 -5

index 25688fa..2c5b201 100644
@@ -1,4 +1,5 @@
  /*
+ * Copyright (c) 2014 Open Grid Computing, Inc. All rights reserved.
   * Copyright (c) 2005-2007 Network Appliance, Inc. All rights reserved.
   *
   * This software is available to you under a choice of one of two

@@ -160,7 +161,6 @@ struct svc_rdma_req_map *svc_rdma_get_req_map(void)
  		schedule_timeout_uninterruptible(msecs_to_jiffies(500));
  	}
  	map->count = 0;
-	map->frmr = NULL;
  	return map;
  }
 

@@ -336,22 +336,21 @@ static void process_context(struct svcxprt_rdma *xprt,
 
  	switch (ctxt->wr_op) {
  	case IB_WR_SEND:
-		if (test_bit(RDMACTXT_F_FAST_UNREG, &ctxt->flags))
-			svc_rdma_put_frmr(xprt, ctxt->frmr);
+		BUG_ON(ctxt->frmr);
  		svc_rdma_put_context(ctxt, 1);
  		break;
 
  	case IB_WR_RDMA_WRITE:
+		BUG_ON(ctxt->frmr);
  		svc_rdma_put_context(ctxt, 0);
  		break;
 
  	case IB_WR_RDMA_READ:
  	case IB_WR_RDMA_READ_WITH_INV:
+		svc_rdma_put_frmr(xprt, ctxt->frmr);
  		if (test_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags)) {
  			struct svc_rdma_op_ctxt *read_hdr = ctxt->read_hdr;
  			BUG_ON(!read_hdr);
-			if (test_bit(RDMACTXT_F_FAST_UNREG, &ctxt->flags))
-				svc_rdma_put_frmr(xprt, ctxt->frmr);
  			spin_lock_bh(&xprt->sc_rq_dto_lock);
  			set_bit(XPT_DATA, &xprt->sc_xprt.xpt_flags);
  			list_add_tail(&read_hdr->dto_q,

@@ -363,6 +362,7 @@ static void process_context(struct svcxprt_rdma *xprt,
  		break;
 

net/sunrpc/xprtrdma/svc_rdma_transport.c static void process_context(struct svcxprt_rdma *xprt, · line 368

Quoted 5 lines

net/sunrpc/xprtrdma/svc_rdma_transport.c +1 -0

  	default:
+		BUG_ON(1);
  		printk(KERN_ERR "svcrdma: unexpected completion type, "
  		       "opcode=%d\n",
  		       ctxt->wr_op);

Note the printk's unreachable now. Should some of these BUG_ON()'s be WARN_ON()'s?

net/sunrpc/xprtrdma/svc_rdma_transport.c static void process_context(struct svcxprt_rdma *xprt, · line 384

Quoted 9 lines

net/sunrpc/xprtrdma/svc_rdma_transport.c +2 -1

@@ -378,29 +378,42 @@ static void process_context(struct svcxprt_rdma *xprt,
  static void sq_cq_reap(struct svcxprt_rdma *xprt)
  {
  	struct svc_rdma_op_ctxt *ctxt = NULL;
-	struct ib_wc wc;
+	struct ib_wc wc_a[6];
+	struct ib_wc *wc;
  	struct ib_cq *cq = xprt->sc_sq_cq;
  	int ret;

May want to keep an eye on the stack usage here?

--b.

Quoted 72 lines

net/sunrpc/xprtrdma/svc_rdma_transport.c +29 -20

+	memset(wc_a, 0, sizeof(wc_a));
+
  	if (!test_and_clear_bit(RDMAXPRT_SQ_PENDING, &xprt->sc_flags))
  		return;
 
  	ib_req_notify_cq(xprt->sc_sq_cq, IB_CQ_NEXT_COMP);
  	atomic_inc(&rdma_stat_sq_poll);
-	while ((ret = ib_poll_cq(cq, 1, &wc)) > 0) {
-		if (wc.status != IB_WC_SUCCESS)
-			/* Close the transport */
-			set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
+	while ((ret = ib_poll_cq(cq, ARRAY_SIZE(wc_a), wc_a)) > 0) {
+		int i;
 
-		/* Decrement used SQ WR count */
-		atomic_dec(&xprt->sc_sq_count);
-		wake_up(&xprt->sc_send_wait);
+		for (i = 0; i < ret; i++) {
+			wc = &wc_a[i];
+			if (wc->status != IB_WC_SUCCESS) {
+				dprintk("svcrdma: sq wc err status %d\n",
+					wc->status);
 
-		ctxt = (struct svc_rdma_op_ctxt *)(unsigned long)wc.wr_id;
-		if (ctxt)
-			process_context(xprt, ctxt);
+				/* Close the transport */
+				set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
+			}
 
-		svc_xprt_put(&xprt->sc_xprt);
+			/* Decrement used SQ WR count */
+			atomic_dec(&xprt->sc_sq_count);
+			wake_up(&xprt->sc_send_wait);
+
+			ctxt = (struct svc_rdma_op_ctxt *)
+				(unsigned long)wc->wr_id;
+			if (ctxt)
+				process_context(xprt, ctxt);
+
+			svc_xprt_put(&xprt->sc_xprt);
+		}
  	}
 
  	if (ctxt)

@@ -993,7 +1006,11 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
  			need_dma_mr = 0;
  		break;
  	case RDMA_TRANSPORT_IB:
-		if (!(devattr.device_cap_flags & IB_DEVICE_LOCAL_DMA_LKEY)) {
+		if (!(newxprt->sc_dev_caps & SVCRDMA_DEVCAP_FAST_REG)) {
+			need_dma_mr = 1;
+			dma_mr_acc = IB_ACCESS_LOCAL_WRITE;
+		} else if (!(devattr.device_cap_flags &
+			     IB_DEVICE_LOCAL_DMA_LKEY)) {
  			need_dma_mr = 1;
  			dma_mr_acc = IB_ACCESS_LOCAL_WRITE;
  		} else

@@ -1190,14 +1207,7 @@ static int svc_rdma_has_wspace(struct svc_xprt *xprt)
  		container_of(xprt, struct svcxprt_rdma, sc_xprt);
 
  	/*
-	 * If there are fewer SQ WR available than required to send a
-	 * simple response, return false.
-	 */
-	if ((rdma->sc_sq_depth - atomic_read(&rdma->sc_sq_count) < 3))
-		return 0;
-
-	/*
-	 * ...or there are already waiters on the SQ,
+	 * If there are already waiters on the SQ,

net/sunrpc/xprtrdma/svc_rdma_transport.c static int svc_rdma_has_wspace(struct svc_xprt *xprt) · line 1213

Quoted 4 lines

net/sunrpc/xprtrdma/svc_rdma_transport.c +0 -0

  	 * return false.
  	 */
  	if (waitqueue_active(&rdma->sc_send_wait))

--
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Quoted 78 lines · J. Bruce Fields

Quoted 77 lines · Steve Wise

From: Tom Tucker <[email protected]>

Change poll logic to grab up to 6 completions at a time.

RDMA write and send completions no longer deal with fastreg objects.

Set SVCRDMA_DEVCAP_FAST_REG and allocate a dma_mr based on the device capabilities.

Signed-off-by Tom Tucker <[email protected]>

Signed-off-by Steve Wise <[email protected]>

---

 include/linux/sunrpc/svc_rdma.h          |    3 -
 net/sunrpc/xprtrdma/svc_rdma_transport.c |   62 +++++++++++++++++-------------
 2 files changed, 37 insertions(+), 28 deletions(-)

include/linux/sunrpc/svc_rdma.h +1 -2

index 0b8e3e6..5cf99a0 100644
@@ -115,14 +115,13 @@ struct svc_rdma_fastreg_mr {
 	struct list_head frmr_list;
 };
 struct svc_rdma_req_map {
-	struct svc_rdma_fastreg_mr *frmr;
 	unsigned long count;
 	union {
 		struct kvec sge[RPCSVC_MAXPAGES];
 		struct svc_rdma_chunk_sge ch[RPCSVC_MAXPAGES];
+		unsigned long lkey[RPCSVC_MAXPAGES];
 	};
 };
-#define RDMACTXT_F_FAST_UNREG	1
 #define RDMACTXT_F_LAST_CTXT	2
 #define	SVCRDMA_DEVCAP_FAST_REG		1	/* fast mr registration */

net/sunrpc/xprtrdma/svc_rdma_transport.c +4 -5

index 25688fa..2c5b201 100644
@@ -1,4 +1,5 @@
 /*
+ * Copyright (c) 2014 Open Grid Computing, Inc. All rights reserved.
  * Copyright (c) 2005-2007 Network Appliance, Inc. All rights reserved.
  *
  * This software is available to you under a choice of one of two

@@ -160,7 +161,6 @@ struct svc_rdma_req_map *svc_rdma_get_req_map(void)
 		schedule_timeout_uninterruptible(msecs_to_jiffies(500));
 	}
 	map->count = 0;
-	map->frmr = NULL;
 	return map;
 }

@@ -336,22 +336,21 @@ static void process_context(struct svcxprt_rdma *xprt,
 	switch (ctxt->wr_op) {
 	case IB_WR_SEND:
-		if (test_bit(RDMACTXT_F_FAST_UNREG, &ctxt->flags))
-			svc_rdma_put_frmr(xprt, ctxt->frmr);
+		BUG_ON(ctxt->frmr);
 		svc_rdma_put_context(ctxt, 1);
 		break;
 	case IB_WR_RDMA_WRITE:
+		BUG_ON(ctxt->frmr);
 		svc_rdma_put_context(ctxt, 0);
 		break;
 	case IB_WR_RDMA_READ:
 	case IB_WR_RDMA_READ_WITH_INV:
+		svc_rdma_put_frmr(xprt, ctxt->frmr);
 		if (test_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags)) {
 			struct svc_rdma_op_ctxt *read_hdr = ctxt->read_hdr;
 			BUG_ON(!read_hdr);
-			if (test_bit(RDMACTXT_F_FAST_UNREG, &ctxt->flags))
-				svc_rdma_put_frmr(xprt, ctxt->frmr);
 			spin_lock_bh(&xprt->sc_rq_dto_lock);
 			set_bit(XPT_DATA, &xprt->sc_xprt.xpt_flags);
 			list_add_tail(&read_hdr->dto_q,

@@ -363,6 +362,7 @@ static void process_context(struct svcxprt_rdma *xprt,

Quoted 8 lines

net/sunrpc/xprtrdma/svc_rdma_transport.c static void process_context(struct svcxprt_rdma *xprt, · line 368

Quoted 6 lines

net/sunrpc/xprtrdma/svc_rdma_transport.c +1 -0

 		break;
 	default:
+		BUG_ON(1);
 		printk(KERN_ERR "svcrdma: unexpected completion type, "
 		       "opcode=%d\n",
 		       ctxt->wr_op);

Note the printk's unreachable now. Should some of these BUG_ON()'s be WARN_ON()'s?

I'll remove the printk. And if any of the new BUG_ON()'s can be WARN_ON(), then I'll do that. But only if proceeding after a WARN_ON() results in a working server.

From: Tom Tucker <[email protected]>

Based on device support, RDMA read target sgls are fast-registered, or composed using the local dma lkey or a dma_mr lkey. A given NFS Write chunk list will be split into a set of rdma reads based on the limitations of the device.

Signed-off-by Tom Tucker <[email protected]>

Signed-off-by Steve Wise <[email protected]>

---

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 633 +++++++++++++------------------

1 files changed, 259 insertions(+), 374 deletions(-)

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +218 -258

index 8d904e4..1c4c285 100644
@@ -1,4 +1,5 @@
 /*
+ * Copyright (c) 2014 Open Grid Computing, Inc. All rights reserved.
 * Copyright (c) 2005-2006 Network Appliance, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two

@@ -69,7 +70,8 @@ static void rdma_build_arg_xdr(struct svc_rqst *rqstp,
 
 	/* Set up the XDR head */
 	rqstp->rq_arg.head[0].iov_base = page_address(page);
-	rqstp->rq_arg.head[0].iov_len = min(byte_count, ctxt->sge[0].length);
+	rqstp->rq_arg.head[0].iov_len =
+		min_t(size_t, byte_count, ctxt->sge[0].length);
 	rqstp->rq_arg.len = byte_count;
 	rqstp->rq_arg.buflen = byte_count;
 

@@ -85,7 +87,7 @@ static void rdma_build_arg_xdr(struct svc_rqst *rqstp,
 		page = ctxt->pages[sge_no];
 		put_page(rqstp->rq_pages[sge_no]);
 		rqstp->rq_pages[sge_no] = page;
-		bc -= min(bc, ctxt->sge[sge_no].length);
+		bc -= min_t(u32, bc, ctxt->sge[sge_no].length);
 		rqstp->rq_arg.buflen += ctxt->sge[sge_no].length;
 		sge_no++;
 	}

@@ -113,291 +115,249 @@ static void rdma_build_arg_xdr(struct svc_rqst *rqstp,
 	rqstp->rq_arg.tail[0].iov_len = 0;
 }
 
-/* Encode a read-chunk-list as an array of IB SGE
- *
- * Assumptions:
- * - chunk[0]->position points to pages[0] at an offset of 0
- * - pages[] is not physically or virtually contiguous and consists of
- *   PAGE_SIZE elements.
- *
- * Output:
- * - sge array pointing into pages[] array.
- * - chunk_sge array specifying sge index and count for each
- *   chunk in the read list
- *
- */
-static int map_read_chunks(struct svcxprt_rdma *xprt,
-			   struct svc_rqst *rqstp,
-			   struct svc_rdma_op_ctxt *head,
-			   struct rpcrdma_msg *rmsgp,
-			   struct svc_rdma_req_map *rpl_map,
-			   struct svc_rdma_req_map *chl_map,
-			   int ch_count,
-			   int byte_count)
+static int rdma_read_max_sge(struct svcxprt_rdma *xprt, int sge_count)
 {
-	int sge_no;
-	int sge_bytes;
-	int page_off;
-	int page_no;
-	int ch_bytes;
-	int ch_no;
-	struct rpcrdma_read_chunk *ch;
+	if (rdma_node_get_transport(xprt->sc_cm_id->device->node_type) ==
+	     RDMA_TRANSPORT_IWARP)
+		return 1;
+	else
+		return min_t(int, sge_count, xprt->sc_max_sge);
+}
 
-	sge_no = 0;
-	page_no = 0;
-	page_off = 0;
-	ch = (struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];
-	ch_no = 0;
-	ch_bytes = ntohl(ch->rc_target.rs_length);
-	head->arg.head[0] = rqstp->rq_arg.head[0];
-	head->arg.tail[0] = rqstp->rq_arg.tail[0];
-	head->arg.pages = &head->pages[head->count];
-	head->hdr_count = head->count; /* save count of hdr pages */
-	head->arg.page_base = 0;
-	head->arg.page_len = ch_bytes;
-	head->arg.len = rqstp->rq_arg.len + ch_bytes;
-	head->arg.buflen = rqstp->rq_arg.buflen + ch_bytes;
-	head->count++;
-	chl_map->ch[0].start = 0;
-	while (byte_count) {
-		rpl_map->sge[sge_no].iov_base =
-			page_address(rqstp->rq_arg.pages[page_no]) + page_off;
-		sge_bytes = min_t(int, PAGE_SIZE-page_off, ch_bytes);
-		rpl_map->sge[sge_no].iov_len = sge_bytes;
-		/*
-		 * Don't bump head->count here because the same page
-		 * may be used by multiple SGE.
-		 */
-		head->arg.pages[page_no] = rqstp->rq_arg.pages[page_no];
-		rqstp->rq_respages = &rqstp->rq_arg.pages[page_no+1];
+typedef int (*rdma_reader_fn)(struct svcxprt_rdma *xprt,
+			      struct svc_rqst *rqstp,
+			      struct svc_rdma_op_ctxt *head,
+			      int *page_no,
+			      u32 *page_offset,
+			      u32 rs_handle,
+			      u32 rs_length,
+			      u64 rs_offset,
+			      int last);
+
+/* Issue an RDMA_READ using the local lkey to map the data sink */
+static int rdma_read_chunk_lcl(struct svcxprt_rdma *xprt,
+			       struct svc_rqst *rqstp,
+			       struct svc_rdma_op_ctxt *head,
+			       int *page_no,
+			       u32 *page_offset,
+			       u32 rs_handle,
+			       u32 rs_length,
+			       u64 rs_offset,
+			       int last)
+{
+	struct ib_send_wr read_wr;
+	int pages_needed = PAGE_ALIGN(*page_offset + rs_length) >> PAGE_SHIFT;
+	struct svc_rdma_op_ctxt *ctxt = svc_rdma_get_context(xprt);
+	int ret, read, pno;
+	u32 pg_off = *page_offset;
+	u32 pg_no = *page_no;
+
+	ctxt->direction = DMA_FROM_DEVICE;
+	ctxt->read_hdr = head;
+	pages_needed =
+		min_t(int, pages_needed, rdma_read_max_sge(xprt, pages_needed));
+	read = min_t(int, pages_needed << PAGE_SHIFT, rs_length);
+
+	for (pno = 0; pno < pages_needed; pno++) {
+		int len = min_t(int, rs_length, PAGE_SIZE - pg_off);
+
+		head->arg.pages[pg_no] = rqstp->rq_arg.pages[pg_no];
+		head->arg.page_len += len;
+		head->arg.len += len;
+		head->count++;
+		rqstp->rq_respages = &rqstp->rq_arg.pages[pg_no+1];
 		rqstp->rq_next_page = rqstp->rq_respages + 1;
+		ctxt->sge[pno].addr =
+			ib_dma_map_page(xprt->sc_cm_id->device,
+					head->arg.pages[pg_no], pg_off,
+					PAGE_SIZE - pg_off,
+					DMA_FROM_DEVICE);
+		ret = ib_dma_mapping_error(xprt->sc_cm_id->device,
+					   ctxt->sge[pno].addr);
+		if (ret)
+			goto err;
+		atomic_inc(&xprt->sc_dma_used);
 
-		byte_count -= sge_bytes;
-		ch_bytes -= sge_bytes;
-		sge_no++;
-		/*
-		 * If all bytes for this chunk have been mapped to an
-		 * SGE, move to the next SGE
-		 */
-		if (ch_bytes == 0) {
-			chl_map->ch[ch_no].count =
-				sge_no - chl_map->ch[ch_no].start;
-			ch_no++;
-			ch++;
-			chl_map->ch[ch_no].start = sge_no;
-			ch_bytes = ntohl(ch->rc_target.rs_length);
-			/* If bytes remaining account for next chunk */
-			if (byte_count) {
-				head->arg.page_len += ch_bytes;
-				head->arg.len += ch_bytes;
-				head->arg.buflen += ch_bytes;
-			}
-		}
-		/*
-		 * If this SGE consumed all of the page, move to the
-		 * next page
-		 */
-		if ((sge_bytes + page_off) == PAGE_SIZE) {
-			page_no++;
-			page_off = 0;
-			/*
-			 * If there are still bytes left to map, bump
-			 * the page count
-			 */
-			if (byte_count)
-				head->count++;
-		} else
-			page_off += sge_bytes;
+		/* The lkey here is either a local dma lkey or a dma_mr lkey */
+		ctxt->sge[pno].lkey = xprt->sc_dma_lkey;
+		ctxt->sge[pno].length = len;
+		ctxt->count++;
+
+		pg_no++;
+		pg_off = 0;
+		rs_length -= len;
+	}
+
+	if (last && rs_length == 0)
+		set_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
+	else
+		clear_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
+
+	memset(&read_wr, 0, sizeof(read_wr));
+	read_wr.wr_id = (unsigned long)ctxt;
+	read_wr.opcode = IB_WR_RDMA_READ;
+	ctxt->wr_op = read_wr.opcode;
+	read_wr.send_flags = IB_SEND_SIGNALED;
+	read_wr.wr.rdma.rkey = rs_handle;
+	read_wr.wr.rdma.remote_addr = rs_offset;
+	read_wr.sg_list = ctxt->sge;
+	read_wr.num_sge = pages_needed;
+
+	ret = svc_rdma_send(xprt, &read_wr);
+	if (ret) {
+		pr_err("svcrdma: Error %d posting RDMA_READ\n", ret);
+		set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
+		goto err;
 	}
-	BUG_ON(byte_count != 0);
-	return sge_no;
+	*page_no = pg_no;
+	*page_offset = pg_off;
+	ret = read;
+	atomic_inc(&rdma_stat_read);
+	return ret;
+ err:
+	svc_rdma_unmap_dma(ctxt);
+	svc_rdma_put_context(ctxt, 0);
+	return ret;
 }
 
-/* Map a read-chunk-list to an XDR and fast register the page-list.
- *
- * Assumptions:
- * - chunk[0]	position points to pages[0] at an offset of 0
- * - pages[]	will be made physically contiguous by creating a one-off memory
- *		region using the fastreg verb.
- * - byte_count is # of bytes in read-chunk-list
- * - ch_count	is # of chunks in read-chunk-list
- *
- * Output:
- * - sge array pointing into pages[] array.
- * - chunk_sge array specifying sge index and count for each
- *   chunk in the read list
- */
-static int fast_reg_read_chunks(struct svcxprt_rdma *xprt,
+/* Issue an RDMA_READ using an FRMR to map the data sink */
+static int rdma_read_chunk_frmr(struct svcxprt_rdma *xprt,
 				struct svc_rqst *rqstp,
 				struct svc_rdma_op_ctxt *head,
-				struct rpcrdma_msg *rmsgp,
-				struct svc_rdma_req_map *rpl_map,
-				struct svc_rdma_req_map *chl_map,
-				int ch_count,
-				int byte_count)
+				int *page_no,
+				u32 *page_offset,
+				u32 rs_handle,
+				u32 rs_length,
+				u64 rs_offset,
+				int last)
 {
-	int page_no;
-	int ch_no;
-	u32 offset;
-	struct rpcrdma_read_chunk *ch;
-	struct svc_rdma_fastreg_mr *frmr;
-	int ret = 0;
+	struct ib_send_wr read_wr;
+	struct ib_send_wr inv_wr;
+	struct ib_send_wr fastreg_wr;
+	u8 key;
+	int pages_needed = PAGE_ALIGN(*page_offset + rs_length) >> PAGE_SHIFT;
+	struct svc_rdma_op_ctxt *ctxt = svc_rdma_get_context(xprt);
+	struct svc_rdma_fastreg_mr *frmr = svc_rdma_get_frmr(xprt);
+	int ret, read, pno;
+	u32 pg_off = *page_offset;
+	u32 pg_no = *page_no;
 
-	frmr = svc_rdma_get_frmr(xprt);
 	if (IS_ERR(frmr))
 		return -ENOMEM;
 
-	head->frmr = frmr;
-	head->arg.head[0] = rqstp->rq_arg.head[0];
-	head->arg.tail[0] = rqstp->rq_arg.tail[0];
-	head->arg.pages = &head->pages[head->count];
-	head->hdr_count = head->count; /* save count of hdr pages */
-	head->arg.page_base = 0;
-	head->arg.page_len = byte_count;
-	head->arg.len = rqstp->rq_arg.len + byte_count;
-	head->arg.buflen = rqstp->rq_arg.buflen + byte_count;
+	ctxt->direction = DMA_FROM_DEVICE;
+	ctxt->frmr = frmr;
+	pages_needed = min_t(int, pages_needed, xprt->sc_frmr_pg_list_len);
+	read = min_t(int, pages_needed << PAGE_SHIFT, rs_length);
 
-	/* Fast register the page list */
-	frmr->kva = page_address(rqstp->rq_arg.pages[0]);
+	frmr->kva = page_address(rqstp->rq_arg.pages[pg_no]);
 	frmr->direction = DMA_FROM_DEVICE;
 	frmr->access_flags = (IB_ACCESS_LOCAL_WRITE|IB_ACCESS_REMOTE_WRITE);
-	frmr->map_len = byte_count;
-	frmr->page_list_len = PAGE_ALIGN(byte_count) >> PAGE_SHIFT;
-	for (page_no = 0; page_no < frmr->page_list_len; page_no++) {
-		frmr->page_list->page_list[page_no] =
+	frmr->map_len = pages_needed << PAGE_SHIFT;
+	frmr->page_list_len = pages_needed;
+
+	for (pno = 0; pno < pages_needed; pno++) {
+		int len = min_t(int, rs_length, PAGE_SIZE - pg_off);
+
+		head->arg.pages[pg_no] = rqstp->rq_arg.pages[pg_no];
+		head->arg.page_len += len;
+		head->arg.len += len;
+		head->count++;
+		rqstp->rq_respages = &rqstp->rq_arg.pages[pg_no+1];
+		rqstp->rq_next_page = rqstp->rq_respages + 1;
+		frmr->page_list->page_list[pno] =
 			ib_dma_map_page(xprt->sc_cm_id->device,
-					rqstp->rq_arg.pages[page_no], 0,
+					head->arg.pages[pg_no], 0,
 					PAGE_SIZE, DMA_FROM_DEVICE);
-		if (ib_dma_mapping_error(xprt->sc_cm_id->device,
-					 frmr->page_list->page_list[page_no]))
-			goto fatal_err;
+		ret = ib_dma_mapping_error(xprt->sc_cm_id->device,
+					   frmr->page_list->page_list[pno]);
+		if (ret)
+			goto err;
 		atomic_inc(&xprt->sc_dma_used);
-		head->arg.pages[page_no] = rqstp->rq_arg.pages[page_no];
+		pg_no++;
+		pg_off = 0;
 	}
-	head->count += page_no;
 
-	/* rq_respages points one past arg pages */
-	rqstp->rq_respages = &rqstp->rq_arg.pages[page_no];
-	rqstp->rq_next_page = rqstp->rq_respages + 1;
+	if (last && read == rs_length)
+		set_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
+	else
+		clear_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
 
-	/* Create the reply and chunk maps */
-	offset = 0;
-	ch = (struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];
-	for (ch_no = 0; ch_no < ch_count; ch_no++) {
-		int len = ntohl(ch->rc_target.rs_length);
-		rpl_map->sge[ch_no].iov_base = frmr->kva + offset;
-		rpl_map->sge[ch_no].iov_len = len;
-		chl_map->ch[ch_no].count = 1;
-		chl_map->ch[ch_no].start = ch_no;
-		offset += len;
-		ch++;
+	/* Bump the key */
+	key = (u8)(frmr->mr->lkey & 0x000000FF);
+	ib_update_fast_reg_key(frmr->mr, ++key);
+
+	ctxt->sge[0].addr = (unsigned long)frmr->kva;
+	ctxt->sge[0].lkey = frmr->mr->lkey;
+	ctxt->sge[0].length = read;
+	ctxt->count = 1;
+	ctxt->read_hdr = head;
+
+	/* Prepare FASTREG WR */
+	memset(&fastreg_wr, 0, sizeof(fastreg_wr));
+	fastreg_wr.opcode = IB_WR_FAST_REG_MR;
+	fastreg_wr.send_flags = IB_SEND_SIGNALED;
+	fastreg_wr.wr.fast_reg.iova_start = (unsigned long)frmr->kva;
+	fastreg_wr.wr.fast_reg.page_list = frmr->page_list;
+	fastreg_wr.wr.fast_reg.page_list_len = frmr->page_list_len;
+	fastreg_wr.wr.fast_reg.page_shift = PAGE_SHIFT;
+	fastreg_wr.wr.fast_reg.length = frmr->map_len;
+	fastreg_wr.wr.fast_reg.access_flags = frmr->access_flags;
+	fastreg_wr.wr.fast_reg.rkey = frmr->mr->lkey;
+	fastreg_wr.next = &read_wr;
+
+	/* Prepare RDMA_READ */
+	memset(&read_wr, 0, sizeof(read_wr));
+	read_wr.send_flags = IB_SEND_SIGNALED;
+	read_wr.wr.rdma.rkey = rs_handle;
+	read_wr.wr.rdma.remote_addr = rs_offset;
+	read_wr.sg_list = ctxt->sge;
+	read_wr.num_sge = 1;
+	if (xprt->sc_dev_caps & SVCRDMA_DEVCAP_READ_W_INV) {
+		read_wr.opcode = IB_WR_RDMA_READ_WITH_INV;
+		read_wr.wr_id = (unsigned long)ctxt;
+		read_wr.ex.invalidate_rkey = ctxt->frmr->mr->lkey;
+	} else {
+		read_wr.opcode = IB_WR_RDMA_READ;
+		read_wr.next = &inv_wr;
+		/* Prepare invalidate */
+		memset(&inv_wr, 0, sizeof(inv_wr));
+		inv_wr.wr_id = (unsigned long)ctxt;
+		inv_wr.opcode = IB_WR_LOCAL_INV;
+		inv_wr.send_flags = IB_SEND_SIGNALED;
+		inv_wr.ex.invalidate_rkey = frmr->mr->lkey;
 	}
-
-	ret = svc_rdma_fastreg(xprt, frmr);
-	if (ret)
-		goto fatal_err;
-
-	return ch_no;
-
- fatal_err:
-	printk("svcrdma: error fast registering xdr for xprt %p", xprt);
-	svc_rdma_put_frmr(xprt, frmr);
-	return -EIO;
-}
-
-static int rdma_set_ctxt_sge(struct svcxprt_rdma *xprt,
-			     struct svc_rdma_op_ctxt *ctxt,
-			     struct svc_rdma_fastreg_mr *frmr,
-			     struct kvec *vec,
-			     u64 *sgl_offset,
-			     int count)
-{
-	int i;
-	unsigned long off;
-
-	ctxt->count = count;
-	ctxt->direction = DMA_FROM_DEVICE;
-	for (i = 0; i < count; i++) {
-		ctxt->sge[i].length = 0; /* in case map fails */
-		if (!frmr) {
-			BUG_ON(!virt_to_page(vec[i].iov_base));
-			off = (unsigned long)vec[i].iov_base & ~PAGE_MASK;
-			ctxt->sge[i].addr =
-				ib_dma_map_page(xprt->sc_cm_id->device,
-						virt_to_page(vec[i].iov_base),
-						off,
-						vec[i].iov_len,
-						DMA_FROM_DEVICE);
-			if (ib_dma_mapping_error(xprt->sc_cm_id->device,
-						 ctxt->sge[i].addr))
-				return -EINVAL;
-			ctxt->sge[i].lkey = xprt->sc_dma_lkey;
-			atomic_inc(&xprt->sc_dma_used);
-		} else {
-			ctxt->sge[i].addr = (unsigned long)vec[i].iov_base;
-			ctxt->sge[i].lkey = frmr->mr->lkey;
-		}
-		ctxt->sge[i].length = vec[i].iov_len;
-		*sgl_offset = *sgl_offset + vec[i].iov_len;
+	ctxt->wr_op = read_wr.opcode;
+
+	/* Post the chain */
+	ret = svc_rdma_send(xprt, &fastreg_wr);
+	if (ret) {
+		pr_err("svcrdma: Error %d posting RDMA_READ\n", ret);
+		set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
+		goto err;
 	}
-	return 0;
-}
-
-static int rdma_read_max_sge(struct svcxprt_rdma *xprt, int sge_count)
-{
-	if ((rdma_node_get_transport(xprt->sc_cm_id->device->node_type) ==
-	     RDMA_TRANSPORT_IWARP) &&
-	    sge_count > 1)
-		return 1;
-	else
-		return min_t(int, sge_count, xprt->sc_max_sge);
+	*page_no = pg_no;
+	*page_offset = pg_off;
+	ret = read;
+	atomic_inc(&rdma_stat_read);
+	return ret;
+ err:
+	svc_rdma_unmap_dma(ctxt);
+	svc_rdma_put_context(ctxt, 0);
+	svc_rdma_put_frmr(xprt, frmr);
+	return ret;
 }
 
-/*
- * Use RDMA_READ to read data from the advertised client buffer into the
- * XDR stream starting at rq_arg.head[0].iov_base.
- * Each chunk in the array
- * contains the following fields:
- * discrim      - '1', This isn't used for data placement
- * position     - The xdr stream offset (the same for every chunk)
- * handle       - RMR for client memory region
- * length       - data transfer length
- * offset       - 64 bit tagged offset in remote memory region
- *
- * On our side, we need to read into a pagelist. The first page immediately
- * follows the RPC header.
- *
- * This function returns:
- * 0 - No error and no read-list found.
- *
- * 1 - Successful read-list processing. The data is not yet in
- * the pagelist and therefore the RPC request must be deferred. The
- * I/O completion will enqueue the transport again and
- * svc_rdma_recvfrom will complete the request.
- *
- * <0 - Error processing/posting read-list.
- *
- * NOTE: The ctxt must not be touched after the last WR has been posted
- * because the I/O completion processing may occur on another
- * processor and free / modify the context. Ne touche pas!
- */
-static int rdma_read_xdr(struct svcxprt_rdma *xprt,
-			 struct rpcrdma_msg *rmsgp,
-			 struct svc_rqst *rqstp,
-			 struct svc_rdma_op_ctxt *hdr_ctxt)
+static int rdma_read_chunks(struct svcxprt_rdma *xprt,
+			    struct rpcrdma_msg *rmsgp,
+			    struct svc_rqst *rqstp,
+			    struct svc_rdma_op_ctxt *head)
 {
-	struct ib_send_wr read_wr;
-	struct ib_send_wr inv_wr;
-	int err = 0;
-	int ch_no;
-	int ch_count;
-	int byte_count;
-	int sge_count;
-	u64 sgl_offset;
+	int page_no, ch_count, ret;
 	struct rpcrdma_read_chunk *ch;
-	struct svc_rdma_op_ctxt *ctxt = NULL;
-	struct svc_rdma_req_map *rpl_map;
-	struct svc_rdma_req_map *chl_map;
+	u32 page_offset, byte_count;
+	u64 rs_offset;
+	rdma_reader_fn reader;
 
 	/* If no read list is present, return 0 */
 	ch = svc_rdma_get_read_chunk(rmsgp);

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +13 -19

-	/* Allocate temporary reply and chunk maps */
-	rpl_map = svc_rdma_get_req_map();
-	chl_map = svc_rdma_get_req_map();
-
-	if (!xprt->sc_frmr_pg_list_len)
-		sge_count = map_read_chunks(xprt, rqstp, hdr_ctxt, rmsgp,
-					    rpl_map, chl_map, ch_count,
-					    byte_count);
-	else
-		sge_count = fast_reg_read_chunks(xprt, rqstp, hdr_ctxt, rmsgp,
-						 rpl_map, chl_map, ch_count,
-						 byte_count);
-	if (sge_count < 0) {
-		err = -EIO;
-		goto out;
-	}
-
-	sgl_offset = 0;
-	ch_no = 0;
+	/* The request is completed when the RDMA_READs complete. The
+	 * head context keeps all the pages that comprise the
+	 * request.
+	 */
+	head->arg.head[0] = rqstp->rq_arg.head[0];
+	head->arg.tail[0] = rqstp->rq_arg.tail[0];
+	head->arg.pages = &head->pages[head->count];
+	head->hdr_count = head->count;
+	head->arg.page_base = 0;
+	head->arg.page_len = 0;
+	head->arg.len = rqstp->rq_arg.len;
+	head->arg.buflen = rqstp->rq_arg.buflen + PAGE_SIZE;
 
+	page_no = 0; page_offset = 0;
 	for (ch = (struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +0 -59

-		/* Prepare READ WR */
-		memset(&read_wr, 0, sizeof read_wr);
-		read_wr.wr_id = (unsigned long)ctxt;
-		read_wr.opcode = IB_WR_RDMA_READ;
-		ctxt->wr_op = read_wr.opcode;
-		read_wr.send_flags = IB_SEND_SIGNALED;
-		read_wr.wr.rdma.rkey = ntohl(ch->rc_target.rs_handle);
 		xdr_decode_hyper((__be32 *)&ch->rc_target.rs_offset,
 				 &rs_offset);
-		read_wr.wr.rdma.remote_addr = rs_offset + sgl_offset;
-		read_wr.sg_list = ctxt->sge;
-		read_wr.num_sge =
-			rdma_read_max_sge(xprt, chl_map->ch[ch_no].count);
-		err = rdma_set_ctxt_sge(xprt, ctxt, hdr_ctxt->frmr,
-					&rpl_map->sge[chl_map->ch[ch_no].start],
-					&sgl_offset,
-					read_wr.num_sge);
-		if (err) {
-			svc_rdma_unmap_dma(ctxt);
-			svc_rdma_put_context(ctxt, 0);
-			goto out;
-		}
-		if (((ch+1)->rc_discrim == 0) &&
-		    (read_wr.num_sge == chl_map->ch[ch_no].count)) {
-			/*
-			 * Mark the last RDMA_READ with a bit to
-			 * indicate all RPC data has been fetched from
-			 * the client and the RPC needs to be enqueued.
-			 */
-			set_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
-			if (hdr_ctxt->frmr) {
-				set_bit(RDMACTXT_F_FAST_UNREG, &ctxt->flags);
-				/*
-				 * Invalidate the local MR used to map the data
-				 * sink.
-				 */
-				if (xprt->sc_dev_caps &
-				    SVCRDMA_DEVCAP_READ_W_INV) {
-					read_wr.opcode =
-						IB_WR_RDMA_READ_WITH_INV;
-					ctxt->wr_op = read_wr.opcode;
-					read_wr.ex.invalidate_rkey =
-						ctxt->frmr->mr->lkey;
-				} else {
-					/* Prepare INVALIDATE WR */
-					memset(&inv_wr, 0, sizeof inv_wr);
-					inv_wr.opcode = IB_WR_LOCAL_INV;
-					inv_wr.send_flags = IB_SEND_SIGNALED;
-					inv_wr.ex.invalidate_rkey =
-						hdr_ctxt->frmr->mr->lkey;
-					read_wr.next = &inv_wr;
-				}
-			}
-			ctxt->read_hdr = hdr_ctxt;
-		}
-		/* Post the read */
-		err = svc_rdma_send(xprt, &read_wr);
-		if (err) {
-			printk(KERN_ERR "svcrdma: Error %d posting RDMA_READ\n",
-			       err);
-			set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +20 -27

+		while (byte_count > 0) {
+			ret = reader(xprt, rqstp, head,
+				     &page_no, &page_offset,
+				     ntohl(ch->rc_target.rs_handle),
+				     byte_count, rs_offset,
+				     ((ch+1)->rc_discrim == 0) /* last */
+				     );
+			if (ret < 0)
+				goto err;
+			byte_count -= ret;
+			rs_offset += ret;
 		}
-		atomic_inc(&rdma_stat_read);
-
-		if (read_wr.num_sge < chl_map->ch[ch_no].count) {
-			chl_map->ch[ch_no].count -= read_wr.num_sge;
-			chl_map->ch[ch_no].start += read_wr.num_sge;
-			goto next_sge;
-		}
-		sgl_offset = 0;
-		err = 1;
 	}
-
- out:
-	svc_rdma_put_req_map(rpl_map);
-	svc_rdma_put_req_map(chl_map);
-
+	ret = 1;
+ err:
 	/* Detach arg pages. svc_recv will replenish them */
-	for (ch_no = 0; &rqstp->rq_pages[ch_no] < rqstp->rq_respages; ch_no++)
-		rqstp->rq_pages[ch_no] = NULL;
+	for (page_no = 0;
+	     &rqstp->rq_pages[page_no] < rqstp->rq_respages; page_no++)
+		rqstp->rq_pages[page_no] = NULL;
 
-	return err;
+	return ret;
 }
 
 static int rdma_read_complete(struct svc_rqst *rqstp,

@@ -595,13 +486,9 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
 				  struct svc_rdma_op_ctxt,
 				  dto_q);
 		list_del_init(&ctxt->dto_q);
-	}
-	if (ctxt) {
 		spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock);
 		return rdma_read_complete(rqstp, ctxt);
-	}
-
-	if (!list_empty(&rdma_xprt->sc_rq_dto_q)) {
+	} else if (!list_empty(&rdma_xprt->sc_rq_dto_q)) {
 		ctxt = list_entry(rdma_xprt->sc_rq_dto_q.next,
 				  struct svc_rdma_op_ctxt,
 				  dto_q);

@@ -621,7 +508,6 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
 		if (test_bit(XPT_CLOSE, &xprt->xpt_flags))
 			goto close_out;
 
-		BUG_ON(ret);
 		goto out;
 	}
 	dprintk("svcrdma: processing ctxt=%p on xprt=%p, rqstp=%p, status=%d\n",

@@ -644,12 +530,11 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
 	}
 
 	/* Read read-list data. */
-	ret = rdma_read_xdr(rdma_xprt, rmsgp, rqstp, ctxt);
+	ret = rdma_read_chunks(rdma_xprt, rmsgp, rqstp, ctxt);
 	if (ret > 0) {
 		/* read-list posted, defer until data received from client. */
 		goto defer;
-	}
-	if (ret < 0) {
+	} else if (ret < 0) {
 		/* Post of read-list failed, free context. */
 		svc_rdma_put_context(ctxt, 1);
 		return 0;
 
--

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-----Original Message-----
From: Chuck Lever [mailto:[email protected]]
Sent: Tuesday, May 13, 2014 1:22 PM
To: Steve Wise
Cc: J. Bruce Fields; Linux NFS Mailing List; [email protected]; Tom Tucker
Subject: Re: [PATCH V2 RFC 2/3] svcrdma: Recvfrom changes

Hi Steve-

Some random review comments, see below.

Quoted 22 lines

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +4 -0

+static int rdma_read_chunks(struct svcxprt_rdma *xprt,
+			    struct rpcrdma_msg *rmsgp,
+			    struct svc_rqst *rqstp,
+			    struct svc_rdma_op_ctxt *head)

{

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +1 -8

-	struct ib_send_wr read_wr;
-	struct ib_send_wr inv_wr;
-	int err = 0;
-	int ch_no;
-	int ch_count;
-	int byte_count;
-	int sge_count;
-	u64 sgl_offset;
+	int page_no, ch_count, ret;

	struct rpcrdma_read_chunk *ch;

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +3 -3

-	struct svc_rdma_op_ctxt *ctxt = NULL;
-	struct svc_rdma_req_map *rpl_map;
-	struct svc_rdma_req_map *chl_map;
+	u32 page_offset, byte_count;
+	u64 rs_offset;
+	rdma_reader_fn reader;

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c static int rdma_read_xdr(struct svcxprt_rdma *xprt, · line 369

Quoted 5 lines

	/* If no read list is present, return 0 */
	ch = svc_rdma_get_read_chunk(rmsgp);

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +0 -0

@@ -408,122 +368,53 @@ static int rdma_read_xdr(struct svcxprt_rdma *xprt,
 	if (ch_count > RPCSVC_MAXPAGES)
 		return -EINVAL;

I'm not sure what this ^^^ ch_count check is doing, but maybe I haven't had enough caffeine this morning. Shouldn't this code be comparing the segment count, not the chunk count, with MAXPAGES?

Quoted 37 lines

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +13 -19

-	/* Allocate temporary reply and chunk maps */
-	rpl_map = svc_rdma_get_req_map();
-	chl_map = svc_rdma_get_req_map();
-
-	if (!xprt->sc_frmr_pg_list_len)
-		sge_count = map_read_chunks(xprt, rqstp, hdr_ctxt, rmsgp,
-					    rpl_map, chl_map, ch_count,
-					    byte_count);
-	else
-		sge_count = fast_reg_read_chunks(xprt, rqstp, hdr_ctxt, rmsgp,
-						 rpl_map, chl_map, ch_count,
-						 byte_count);
-	if (sge_count < 0) {
-		err = -EIO;
-		goto out;
-	}
-
-	sgl_offset = 0;
-	ch_no = 0;
+	/* The request is completed when the RDMA_READs complete. The
+	 * head context keeps all the pages that comprise the
+	 * request.
+	 */
+	head->arg.head[0] = rqstp->rq_arg.head[0];
+	head->arg.tail[0] = rqstp->rq_arg.tail[0];
+	head->arg.pages = &head->pages[head->count];
+	head->hdr_count = head->count;
+	head->arg.page_base = 0;
+	head->arg.page_len = 0;
+	head->arg.len = rqstp->rq_arg.len;
+	head->arg.buflen = rqstp->rq_arg.buflen + PAGE_SIZE;
 
+	page_no = 0; page_offset = 0;
 	for (ch = (struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c static int rdma_read_xdr(struct svcxprt_rdma *xprt, · line 386

Quoted 10 lines

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +1 -9

-	     ch->rc_discrim != 0; ch++, ch_no++) {
-		u64 rs_offset;
-next_sge:
-		ctxt = svc_rdma_get_context(xprt);
-		ctxt->direction = DMA_FROM_DEVICE;
-		ctxt->frmr = hdr_ctxt->frmr;
-		ctxt->read_hdr = NULL;
-		clear_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
-		clear_bit(RDMACTXT_F_FAST_UNREG, &ctxt->flags);
+	     ch->rc_discrim != 0; ch++) {

As I understand it, this loop is iterating over the items in the RPC header's read chunk list.

RFC 5667 section 4 says

"The server MUST ignore any Read list for other NFS procedures, as well as additional Read list entries beyond the first in the list."

But rdma_read_chunks() still expects multiple chunks in the incoming list.

Should this code follow the RFC and process only the first chunk in each RPC header, or did I misunderstand the RFC text?

I'm not sure how the RPC layer should enforce the requirement to ignore chunks for particular classes of NFS requests. But seems like valid NFS/RDMA requests will have only zero or one item in each chunk list.

The ramification of this change:

The Linux client sends an extra chunk which is a zero pad to satisfy XDR alignment. This results in an extra RDMA READ on the wire for a payload that is never more than 3 bytes of zeros.

Section 3.7 of RFC 5666 states:

"If in turn, no data remains to be decoded from the inline portion, then the receiver MUST conclude that roundup is present, and therefore it advances the XDR decode position to that indicated by the next chunk (if any). In this way, roundup is passed without ever actually transferring additional XDR bytes."

Later, it states:

"Senders SHOULD therefore avoid encoding individual RDMA Read Chunks for roundup whenever possible."

The Solaris NFS/RDMA server does not require this extra chunk, but Linux appears to need it. When I enable pad optimization on the Linux client, it works fine with the Solaris server. But the first NFS WRITE with an odd length against the Linux server causes connection loss and the client workload hangs.

At some point I'd like to permanently enable this optimization on the Linux client. You can try this out with:

sudo echo 1 > /proc/sys/sunrpc/rdma_pad_optimize

The default contents of this file leave pad optimization disabled, for compatibility with the current Linux NFS/RDMA server.

So rdma_read_chunks() needs to handle the implicit XDR length round-up. That's probably not hard.

What I'm asking is:

Do you agree the server should be changed to comply with section 4 of 5667?

Should you change now in this patch, or do you want me to write a patch for it once the refactoring patch has been accepted?

Quoted 64 lines

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +0 -59

-		/* Prepare READ WR */
-		memset(&read_wr, 0, sizeof read_wr);
-		read_wr.wr_id = (unsigned long)ctxt;
-		read_wr.opcode = IB_WR_RDMA_READ;
-		ctxt->wr_op = read_wr.opcode;
-		read_wr.send_flags = IB_SEND_SIGNALED;
-		read_wr.wr.rdma.rkey = ntohl(ch->rc_target.rs_handle);
 		xdr_decode_hyper((__be32 *)&ch->rc_target.rs_offset,
 				 &rs_offset);
-		read_wr.wr.rdma.remote_addr = rs_offset + sgl_offset;
-		read_wr.sg_list = ctxt->sge;
-		read_wr.num_sge =
-			rdma_read_max_sge(xprt, chl_map->ch[ch_no].count);
-		err = rdma_set_ctxt_sge(xprt, ctxt, hdr_ctxt->frmr,
-					&rpl_map->sge[chl_map->ch[ch_no].start],
-					&sgl_offset,
-					read_wr.num_sge);
-		if (err) {
-			svc_rdma_unmap_dma(ctxt);
-			svc_rdma_put_context(ctxt, 0);
-			goto out;
-		}
-		if (((ch+1)->rc_discrim == 0) &&
-		    (read_wr.num_sge == chl_map->ch[ch_no].count)) {
-			/*
-			 * Mark the last RDMA_READ with a bit to
-			 * indicate all RPC data has been fetched from
-			 * the client and the RPC needs to be enqueued.
-			 */
-			set_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
-			if (hdr_ctxt->frmr) {
-				set_bit(RDMACTXT_F_FAST_UNREG, &ctxt->flags);
-				/*
-				 * Invalidate the local MR used to map the data
-				 * sink.
-				 */
-				if (xprt->sc_dev_caps &
-				    SVCRDMA_DEVCAP_READ_W_INV) {
-					read_wr.opcode =
-						IB_WR_RDMA_READ_WITH_INV;
-					ctxt->wr_op = read_wr.opcode;
-					read_wr.ex.invalidate_rkey =
-						ctxt->frmr->mr->lkey;
-				} else {
-					/* Prepare INVALIDATE WR */
-					memset(&inv_wr, 0, sizeof inv_wr);
-					inv_wr.opcode = IB_WR_LOCAL_INV;
-					inv_wr.send_flags = IB_SEND_SIGNALED;
-					inv_wr.ex.invalidate_rkey =
-						hdr_ctxt->frmr->mr->lkey;
-					read_wr.next = &inv_wr;
-				}
-			}
-			ctxt->read_hdr = hdr_ctxt;
-		}
-		/* Post the read */
-		err = svc_rdma_send(xprt, &read_wr);
-		if (err) {
-			printk(KERN_ERR "svcrdma: Error %d posting RDMA_READ\n",
-			       err);
-			set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c static int rdma_read_xdr(struct svcxprt_rdma *xprt, · line 396

Quoted 10 lines

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +7 -3

-			svc_rdma_unmap_dma(ctxt);
-			svc_rdma_put_context(ctxt, 0);
-			goto out;
+		byte_count = ntohl(ch->rc_target.rs_length);
+
+		/* Use FRMR if supported */
+		if (xprt->sc_dev_caps & SVCRDMA_DEVCAP_FAST_REG)
+			reader = rdma_read_chunk_frmr;
+		else
+			reader = rdma_read_chunk_lcl;

The reader function is invariant across iterations of the for() loop. In fact, it is invariant for all incoming requests on an xprt, isn't it?

Can svc_rdma_create() plant that function pointer in the xprt?

Quoted 13 lines

-----Original Message-----
From: Chuck Lever [mailto:[email protected]]
Sent: Tuesday, May 13, 2014 1:22 PM
To: Steve Wise
Cc: J. Bruce Fields; Linux NFS Mailing List; [email protected]; Tom Tucker
Subject: Re: [PATCH V2 RFC 2/3] svcrdma: Recvfrom changes

Hi Steve-

Some random review comments, see below.

<snip>

Quoted 22 lines

Quoted 22 lines

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +4 -0

+static int rdma_read_chunks(struct svcxprt_rdma *xprt,
+			    struct rpcrdma_msg *rmsgp,
+			    struct svc_rqst *rqstp,
+			    struct svc_rdma_op_ctxt *head)

{

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +1 -8

-	struct ib_send_wr read_wr;
-	struct ib_send_wr inv_wr;
-	int err = 0;
-	int ch_no;
-	int ch_count;
-	int byte_count;
-	int sge_count;
-	u64 sgl_offset;
+	int page_no, ch_count, ret;

	struct rpcrdma_read_chunk *ch;

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +3 -3

-	struct svc_rdma_op_ctxt *ctxt = NULL;
-	struct svc_rdma_req_map *rpl_map;
-	struct svc_rdma_req_map *chl_map;
+	u32 page_offset, byte_count;
+	u64 rs_offset;
+	rdma_reader_fn reader;

Quoted 9 lines

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c static int rdma_read_xdr(struct svcxprt_rdma *xprt, · line 369

Quoted 5 lines

	/* If no read list is present, return 0 */
	ch = svc_rdma_get_read_chunk(rmsgp);

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +0 -0

@@ -408,122 +368,53 @@ static int rdma_read_xdr(struct svcxprt_rdma *xprt,
 	if (ch_count > RPCSVC_MAXPAGES)
 		return -EINVAL;

I'm not sure what this ^^^ ch_count check is doing, but maybe I haven't had enough caffeine this morning. Shouldn't this code be comparing the segment count, not the chunk count, with MAXPAGES?

Isn't ch_count really the number of chunks in the RPC?

I'm not sure what "segment count” you are talking about?

Quoted 55 lines

Quoted 38 lines

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +13 -19

-	/* Allocate temporary reply and chunk maps */
-	rpl_map = svc_rdma_get_req_map();
-	chl_map = svc_rdma_get_req_map();
-
-	if (!xprt->sc_frmr_pg_list_len)
-		sge_count = map_read_chunks(xprt, rqstp, hdr_ctxt, rmsgp,
-					    rpl_map, chl_map, ch_count,
-					    byte_count);
-	else
-		sge_count = fast_reg_read_chunks(xprt, rqstp, hdr_ctxt, rmsgp,
-						 rpl_map, chl_map, ch_count,
-						 byte_count);
-	if (sge_count < 0) {
-		err = -EIO;
-		goto out;
-	}
-
-	sgl_offset = 0;
-	ch_no = 0;
+	/* The request is completed when the RDMA_READs complete. The
+	 * head context keeps all the pages that comprise the
+	 * request.
+	 */
+	head->arg.head[0] = rqstp->rq_arg.head[0];
+	head->arg.tail[0] = rqstp->rq_arg.tail[0];
+	head->arg.pages = &head->pages[head->count];
+	head->hdr_count = head->count;
+	head->arg.page_base = 0;
+	head->arg.page_len = 0;
+	head->arg.len = rqstp->rq_arg.len;
+	head->arg.buflen = rqstp->rq_arg.buflen + PAGE_SIZE;
 
+	page_no = 0; page_offset = 0;
 	for (ch = (struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c static int rdma_read_xdr(struct svcxprt_rdma *xprt, · line 386

Quoted 10 lines

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +1 -9

-	     ch->rc_discrim != 0; ch++, ch_no++) {
-		u64 rs_offset;
-next_sge:
-		ctxt = svc_rdma_get_context(xprt);
-		ctxt->direction = DMA_FROM_DEVICE;
-		ctxt->frmr = hdr_ctxt->frmr;
-		ctxt->read_hdr = NULL;
-		clear_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
-		clear_bit(RDMACTXT_F_FAST_UNREG, &ctxt->flags);
+	     ch->rc_discrim != 0; ch++) {

As I understand it, this loop is iterating over the items in the RPC header's read chunk list.

RFC 5667 section 4 says

Quoted 3 lines

"The server MUST ignore any Read list for other NFS procedures, as well as additional Read list entries beyond the first in the list."

I interpret this to say the server should ignore an RDMA Write list, if present, when processing an NFS WRITE (because the server emits RDMA Reads to the client in this case). Similarly, it should ignore an RDMA Read list when processing an NFS READ (which generates RDMA Writes from the server->client to fulfill the NFS READ).

Quoted 2 lines

But rdma_read_chunks() still expects multiple chunks in the incoming list.

An RDMA Read list can have multiple chunks, yes?

Quoted 9 lines

Should this code follow the RFC and process only the first chunk in each RPC header, or did I misunderstand the RFC text?

I'm not sure how the RPC layer should enforce the requirement to ignore chunks for particular classes of NFS requests. But seems like valid NFS/RDMA requests will have only zero or one item in each chunk list.

Quoted 6 lines

The ramification of this change:

The Linux client sends an extra chunk which is a zero pad to satisfy XDR alignment. This results in an extra RDMA READ on the wire for a payload that is never more than 3 bytes of zeros.

This sounds like a logic bug in the server then.

You see these IOs on the wire?

Quoted 33 lines

Section 3.7 of RFC 5666 states:

"If in turn, no data remains to be decoded from the inline portion, then the receiver MUST conclude that roundup is present, and therefore it advances the XDR decode position to that indicated by the next chunk (if any). In this way, roundup is passed without ever actually transferring additional XDR bytes."

Later, it states:

"Senders SHOULD therefore avoid encoding individual RDMA Read Chunks for roundup whenever possible."

The Solaris NFS/RDMA server does not require this extra chunk, but Linux appears to need it. When I enable pad optimization on the Linux client, it works fine with the Solaris server. But the first NFS WRITE with an odd length against the Linux server causes connection loss and the client workload hangs.

At some point I'd like to permanently enable this optimization on the Linux client. You can try this out with:

sudo echo 1 > /proc/sys/sunrpc/rdma_pad_optimize

The default contents of this file leave pad optimization disabled, for compatibility with the current Linux NFS/RDMA server.

So rdma_read_chunks() needs to handle the implicit XDR length round-up. That's probably not hard.

What I'm asking is:

Quoted 2 lines

Do you agree the server should be changed to comply with section 4 of 5667?

I think it is complying and you are misinterpreting. But I could be misinterpreting it too :)

But we should fix the pad thing.

Quoted 30 lines

Quoted 22 lines

Quoted 22 lines

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +4 -0

+static int rdma_read_chunks(struct svcxprt_rdma *xprt,
+			    struct rpcrdma_msg *rmsgp,
+			    struct svc_rqst *rqstp,
+			    struct svc_rdma_op_ctxt *head)

{

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +1 -8

-	struct ib_send_wr read_wr;
-	struct ib_send_wr inv_wr;
-	int err = 0;
-	int ch_no;
-	int ch_count;
-	int byte_count;
-	int sge_count;
-	u64 sgl_offset;
+	int page_no, ch_count, ret;

	struct rpcrdma_read_chunk *ch;

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +3 -3

-	struct svc_rdma_op_ctxt *ctxt = NULL;
-	struct svc_rdma_req_map *rpl_map;
-	struct svc_rdma_req_map *chl_map;
+	u32 page_offset, byte_count;
+	u64 rs_offset;
+	rdma_reader_fn reader;

Quoted 8 lines

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c static int rdma_read_xdr(struct svcxprt_rdma *xprt, · line 369

Quoted 5 lines

	/* If no read list is present, return 0 */
	ch = svc_rdma_get_read_chunk(rmsgp);

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +0 -0

@@ -408,122 +368,53 @@ static int rdma_read_xdr(struct svcxprt_rdma *xprt,
 	if (ch_count > RPCSVC_MAXPAGES)
 		return -EINVAL;

I'm not sure what this ^^^ ch_count check is doing, but maybe I haven't had enough caffeine this morning. Shouldn't this code be comparing the segment count, not the chunk count, with MAXPAGES?

Quoted 1 line

Isn't ch_count really the number of chunks in the RPC?

Sort of. Block comment in front of svc_rdma_rcl_chunk_counts() reads:

74 * Determine number of chunks and total bytes in chunk list. The chunk 75 * list has already been verified to fit within the RPCRDMA header.

So, called from rdma_read_chunks(), ch_count is the number of chunks in the Read list.

As you point out below, NFS/RDMA passes either a Read or a Write list, not both. So it amounts to the same thing as the total number of chunks in the RPC.

Quoted 1 line

I'm not sure what "segment count” you are talking about?

AFAICT a chunk is a list of segments. Thus one chunk can reference many pages, one per segment.

If you print ch_count, it is 2 for NFS WRITEs from a Linux client, no matter how large the write payload is. Therefore I think the check as it is written is not particularly useful.

The returned ch_count here is not used beyond that check, after the refactoring patch is applied. The returned byte_count includes all chunks in the passed-in chunk list, whereas I think it should count only the first chunk in the list.

Quoted 51 lines

Quoted 51 lines

Quoted 35 lines

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +13 -19

-	/* Allocate temporary reply and chunk maps */
-	rpl_map = svc_rdma_get_req_map();
-	chl_map = svc_rdma_get_req_map();
-
-	if (!xprt->sc_frmr_pg_list_len)
-		sge_count = map_read_chunks(xprt, rqstp, hdr_ctxt, rmsgp,
-					    rpl_map, chl_map, ch_count,
-					    byte_count);
-	else
-		sge_count = fast_reg_read_chunks(xprt, rqstp, hdr_ctxt, rmsgp,
-						 rpl_map, chl_map, ch_count,
-						 byte_count);
-	if (sge_count < 0) {
-		err = -EIO;
-		goto out;
-	}
-
-	sgl_offset = 0;
-	ch_no = 0;
+	/* The request is completed when the RDMA_READs complete. The
+	 * head context keeps all the pages that comprise the
+	 * request.
+	 */
+	head->arg.head[0] = rqstp->rq_arg.head[0];
+	head->arg.tail[0] = rqstp->rq_arg.tail[0];
+	head->arg.pages = &head->pages[head->count];
+	head->hdr_count = head->count;
+	head->arg.page_base = 0;
+	head->arg.page_len = 0;
+	head->arg.len = rqstp->rq_arg.len;
+	head->arg.buflen = rqstp->rq_arg.buflen + PAGE_SIZE;
 
+	page_no = 0; page_offset = 0;
 	for (ch = (struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c static int rdma_read_xdr(struct svcxprt_rdma *xprt, · line 386

Quoted 10 lines

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +1 -9

-	     ch->rc_discrim != 0; ch++, ch_no++) {
-		u64 rs_offset;
-next_sge:
-		ctxt = svc_rdma_get_context(xprt);
-		ctxt->direction = DMA_FROM_DEVICE;
-		ctxt->frmr = hdr_ctxt->frmr;
-		ctxt->read_hdr = NULL;
-		clear_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
-		clear_bit(RDMACTXT_F_FAST_UNREG, &ctxt->flags);
+	     ch->rc_discrim != 0; ch++) {

As I understand it, this loop is iterating over the items in the RPC header's read chunk list.

RFC 5667 section 4 says

Quoted 7 lines

Quoted 3 lines

"The server MUST ignore any Read list for other NFS procedures, as well as additional Read list entries beyond the first in the list."

I interpret this to say the server should ignore an RDMA Write list, if present, when processing an NFS WRITE (because the server emits RDMA Reads to the client in this case). Similarly, it should ignore an RDMA Read list when processing an NFS READ (which generates RDMA Writes from the server->client to fulfill the NFS READ).

That’s already stated explicitly in a later paragraph. So this text is getting at something else, IMO. Here’s the full context:

4. NFS Versions 2 and 3 Mapping

A single RDMA Write list entry MAY be posted by the client to receive either the opaque file data from a READ request or the pathname from a READLINK request. The server MUST ignore a Write list for any other NFS procedure, as well as any Write list entries beyond the first in the list.

Similarly, a single RDMA Read list entry MAY be posted by the client to supply the opaque file data for a WRITE request or the pathname for a SYMLINK request. The server MUST ignore any Read list for other NFS procedures, as well as additional Read list entries beyond the first in the list.

Because there are no NFS version 2 or 3 requests that transfer bulk data in both directions, it is not necessary to post requests containing both Write and Read lists. Any unneeded Read or Write lists are ignored by the server.

If there is a Read list, it can contain one chunk for NFS WRITE and SYMLINK operations, otherwise it should contain zero chunks. Anything else MUST be ignored (ie, the server mustn’t process the additional chunks, and mustn’t throw an error).

Processing the second chunk from the client during NFS WRITE operations is incorrect. The additional chunk should be ignored, and the first chunk should be padded on the server to make things work right in the upper layer (the server’s NFS WRITE XDR decoder).

Quoted 3 lines

Quoted 2 lines

But rdma_read_chunks() still expects multiple chunks in the incoming list.

An RDMA Read list can have multiple chunks, yes?

It can. But RFC 5667 suggests that particularly for NFS requests, only a Read list of zero or one chunks is valid.

Quoted 10 lines

Quoted 10 lines

Should this code follow the RFC and process only the first chunk in each RPC header, or did I misunderstand the RFC text?

I'm not sure how the RPC layer should enforce the requirement to ignore chunks for particular classes of NFS requests. But seems like valid NFS/RDMA requests will have only zero or one item in each chunk list.

The ramification of this change:

Quoted 5 lines

Quoted 4 lines

The Linux client sends an extra chunk which is a zero pad to satisfy XDR alignment. This results in an extra RDMA READ on the wire for a payload that is never more than 3 bytes of zeros.

This sounds like a logic bug in the server then.

Perhaps it’s simply that this code was designed before RFC 5667 was published. Certainly the client expects the server might work this way.

Quoted 1 line

You see these IOs on the wire?

I see extra iterations in the RDMA READ loop on the server, both before and after the refactoring patch.

I haven’t looked at the wire because ib_dump doesn’t work with the mthca provider.

Quoted 30 lines

Quoted 30 lines

Section 3.7 of RFC 5666 states:

"If in turn, no data remains to be decoded from the inline portion, then the receiver MUST conclude that roundup is present, and therefore it advances the XDR decode position to that indicated by the next chunk (if any). In this way, roundup is passed without ever actually transferring additional XDR bytes."

Later, it states:

"Senders SHOULD therefore avoid encoding individual RDMA Read Chunks for roundup whenever possible."

The Solaris NFS/RDMA server does not require this extra chunk, but Linux appears to need it. When I enable pad optimization on the Linux client, it works fine with the Solaris server. But the first NFS WRITE with an odd length against the Linux server causes connection loss and the client workload hangs.

At some point I'd like to permanently enable this optimization on the Linux client. You can try this out with:

sudo echo 1 > /proc/sys/sunrpc/rdma_pad_optimize

The default contents of this file leave pad optimization disabled, for compatibility with the current Linux NFS/RDMA server.

So rdma_read_chunks() needs to handle the implicit XDR length round-up. That's probably not hard.

Quoted 8 lines

Quoted 4 lines

What I'm asking is:

Do you agree the server should be changed to comply with section 4 of 5667?

I think it is complying and you are misinterpreting. But I could be misinterpreting it too :)

But we should fix the pad thing.

That may be enough to support a client that does not send the pad bytes in a separate chunk. However, I wonder how such a server would behave with the current client.

True, this isn’t a regression, per se. The server is already behaving incorrectly without the refactoring patch.

However, Tom’s refactoring rewrites all this logic anyway, and it wouldn’t be much of a stretch to make the server comply with RFC 5667, at this point.

Quoted 4 lines · Chuck Lever

Quoted 2 lines

I'm not sure what "segment count” you are talking about?

AFAICT a chunk is a list of segments. Thus one chunk can reference many pages, one per segment.

Ok yes. rdma_read_chunk_frmr()/rdma_read_chunk_lcl() walk the segments creating rdma read work requests to pull the data for this chunk.

Quoted 3 lines

If you print ch_count, it is 2 for NFS WRITEs from a Linux client, no matter how large the write payload is. Therefore I think the check as it is written is not particularly useful.

Why are there 2?

Quoted 5 lines

The returned ch_count here is not used beyond that check, after the refactoring patch is applied. The returned byte_count includes all chunks in the passed-in chunk list, whereas I think it should count only the first chunk in the list.

So I'll investigate this more with the goal of only grabbing the first chunk.

Quoted 13 lines

Quoted 9 lines

Quoted 5 lines

What I'm asking is:

Do you agree the server should be changed to comply with section 4 of 5667?

I think it is complying and you are misinterpreting. But I could be misinterpreting it too :)

But we should fix the pad thing.

That may be enough to support a client that does not send the pad bytes in a separate chunk. However, I wonder how such a server would behave with the current client.

Quoted 6 lines

True, this isn’t a regression, per se. The server is already behaving incorrectly without the refactoring patch.

However, Tom’s refactoring rewrites all this logic anyway, and it wouldn’t be much of a stretch to make the server comply with RFC 5667, at this point.

Can we defer this until the refactor patch is in, then I'll work on a new patch for the pad stuff.

Quoted 6 lines

Quoted 5 lines

If you print ch_count, it is 2 for NFS WRITEs from a Linux client, no matter how large the write payload is. Therefore I think the check as it is written is not particularly useful.

Quoted 1 line

Why are there 2?

The first chunk lists the pages the server is to read, and the second chunk has the zero pad for XDR alignment.

If pad optimization is enabled on the client, there is just 1 chunk in the RPC's Read list.

Quoted 8 lines

Quoted 7 lines

Quoted 5 lines

If you print ch_count, it is 2 for NFS WRITEs from a Linux client, no matter how large the write payload is. Therefore I think the check as it is written is not particularly useful.

Why are there 2?

Quoted 6 lines

The first chunk lists the pages the server is to read, and the second chunk has the zero pad for XDR alignment.

If pad optimization is enabled on the client, there is just 1 chunk in the RPC's Read list.

So the code as it stands violates the RFC by sending 2 chunks?

And if I change the server
to only consume 1, then everything unaligned will break?

Quoted 4 lines

Quoted 2 lines

So the code as it stands violates the RFC by sending 2 chunks?

The Linux client is non-compliant because it sends two chunks. A compliant server

second chunk, so this is functionally harmless (but a waste of resources).

The Linux server is non-compliant because it _requires_ the XDR pad chunk. A compliant

(eg. Linux with pad optimization enabled) does not interoperate with it.

Quoted 2 lines

And if I change the server
to only consume 1, then everything unaligned will break?

If you change the server to consume only the first chunk, but do not also make it deal

padding as recommended in chapter 3 of RFC 5666, then WRITEs with a length that is not a multiple of four will fail. SYMLINKs with a large payload will also have this problem.

This patch series refactors the NFSRDMA server marshalling logic to remove the intermediary map structures. It also fixes an existing bug where the NFSRDMA server was not minding the device fast register page list length limitations.

I've also made a git repo available with these patches on top of 3.15-rc4:

git://git.openfabrics.org/~swise/linux svcrdma-refactor

Changes since V1:

- fixed regression for devices that don't support FRMRs (see rdma_read_chunk_lcl())

- split patch up for closer review. However I request it be squashed before merging as they is not bisectable, and I think these changes should all be a single commit anyway.

Please review, and test if you can.

Signed-off-by Tom Tucker <[email protected]>

Signed-off-by Steve Wise <[email protected]>

---

Tom Tucker (3):
svcrdma: Sendto changes
svcrdma: Recvfrom changes
svcrdma: Transport and header file changes

 include/linux/sunrpc/svc_rdma.h          |    3 
 net/sunrpc/xprtrdma/svc_rdma_recvfrom.c  |  633 ++++++++++++------------------
 net/sunrpc/xprtrdma/svc_rdma_sendto.c    |  230 +----------
 net/sunrpc/xprtrdma/svc_rdma_transport.c |   62 ++-
 4 files changed, 318 insertions(+), 610 deletions(-)

Signature · 1 line

Steve / Tom

Quoted 11 lines · Steve Wise

This patch series refactors the NFSRDMA server marshalling logic to remove the intermediary map structures. It also fixes an existing bug where the NFSRDMA server was not minding the device fast register page list length limitations.

I've also made a git repo available with these patches on top of 3.15-rc4:

git://git.openfabrics.org/~swise/linux svcrdma-refactor

Changes since V1:

Quoted 6 lines

- fixed regression for devices that don't support FRMRs (see rdma_read_chunk_lcl())

- split patch up for closer review. However I request it be squashed before merging as they is not bisectable, and I think these changes should all be a single commit anyway.

If it's not split up in a way that's bisectable, then yes, just don't bother.

-----Original Message-----
From: [email protected] [mailto:linux-rdma- [email protected]] On Behalf Of Steve Wise
Sent: Wednesday, May 07, 2014 2:39 AM
To: J. Bruce Fields
Cc: [email protected]; [email protected]; [email protected]
Subject: Re: [PATCH V2 RFC 0/3] svcrdma: refactor marshalling logic

Quoted 12 lines · J. Bruce Fields

Quoted 11 lines · Steve Wise

This patch series refactors the NFSRDMA server marshalling logic to remove the intermediary map structures. It also fixes an existing bug where the NFSRDMA server was not minding the device fast register page list length limitations.

I've also made a git repo available with these patches on top of 3.15-rc4:

git://git.openfabrics.org/~swise/linux svcrdma-refactor

Changes since V1:

Quoted 8 lines

Quoted 6 lines

- fixed regression for devices that don't support FRMRs (see rdma_read_chunk_lcl())

- split patch up for closer review. However I request it be squashed before merging as they is not bisectable, and I think these changes should all be a single commit anyway.

If it's not split up in a way that's bisectable, then yes, just don't bother.

I didn't see a good way to split it up, have it bisectable, and not have all the big stuff in one patch. I think its a little more reviewable in these 3 patches, but when I post V3, I'll put it back as an uber patch.
Hopefully folks can have a look at these 3 patches ignoring the bisect
issue. Having said that, the rdma read logic really is better
reviewed by look at the code after applying the patches. That's why I
published a git branch.

Thanks!

Steve.

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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Devesh Sharma
Sent: Monday, May 19, 2014 2:07 PM
To: Steve Wise; J. Bruce Fields
Cc: [email protected]; [email protected]; [email protected]
Subject: RE: [PATCH V2 RFC 0/3] svcrdma: refactor marshalling logic

While testing with ocrdma driver I am finding server side SQ full. Following is the log,

identify why it's happening. Once this is reported Client side crashes due to some

My kdump is not working properly therefore I am not able to analyze the situation

May 19 23:47:02 neo01-el64 kernel: svcrdma: RDMA_WRITE rmr=8008b12, to=45a2d790c,
xdr_off=0, write_len=68, vec->sge=ffff88086cb4a0c8, vec->count=2
May 19 23:47:02 neo01-el64 kernel: svcrdma: send_reply returns 0
May 19 23:47:02 neo01-el64 kernel: svc: server ffff88086409a000 waiting for data (to =
3600000)
May 19 23:47:02 neo01-el64 kernel: svc: transport ffff88087dfa2400 served by daemon
ffff88086409a000
May 19 23:47:02 neo01-el64 kernel: svc: server ffff88086409a000, pool 0, transport
ffff88087dfa2400, inuse=18
May 19 23:47:02 neo01-el64 kernel: svcrdma: rqstp=ffff88086409a000
May 19 23:47:02 neo01-el64 kernel: svcrdma: processing ctxt=ffff880866754540 on
xprt=ffff88087dfa2400, rqstp=ffff88086409a000, status=0
May 19 23:47:02 neo01-el64 kernel: svcrdma: failed to post SQ WR rc=-22, sc_sq_count=0,
sc_sq_depth=128
May 19 23:47:02 neo01-el64 kernel: svcrdma: Error -22 posting RDMA_READ

-----Original Message-----
From: Steve Wise [mailto:[email protected]]
Sent: Tuesday, May 20, 2014 12:44 AM
To: Devesh Sharma; 'J. Bruce Fields'
Cc: [email protected]; [email protected]; [email protected]
Subject: RE: [PATCH V2 RFC 0/3] svcrdma: refactor marshalling logic

Quoted 11 lines

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Devesh Sharma
Sent: Monday, May 19, 2014 2:07 PM
To: Steve Wise; J. Bruce Fields
Cc: [email protected]; [email protected]; [email protected]
Subject: RE: [PATCH V2 RFC 0/3] svcrdma: refactor marshalling logic

While testing with ocrdma driver I am finding server side SQ full. Following is the log,

yet to

Quoted 2 lines

identify why it's happening. Once this is reported Client side crashes due to some

reason.

Quoted 2 lines

My kdump is not working properly therefore I am not able to analyze the situation

properly.

Quoted 18 lines

May 19 23:47:02 neo01-el64 kernel: svcrdma: RDMA_WRITE rmr=8008b12,

to=45a2d790c, xdr_off=0, write_len=68, vec->sge=ffff88086cb4a0c8, vec->count=2 May 19 23:47:02 neo01-el64 kernel: svcrdma: send_reply returns 0 May 19 23:47:02 neo01-el64 kernel: svc: server ffff88086409a000 waiting for data (to =
3600000)

May 19 23:47:02 neo01-el64 kernel: svc: transport ffff88087dfa2400
served by daemon
ffff88086409a000
May 19 23:47:02 neo01-el64 kernel: svc: server ffff88086409a000, pool

0, transport ffff88087dfa2400, inuse=18 May 19 23:47:02 neo01-el64
kernel: svcrdma: rqstp=ffff88086409a000 May 19 23:47:02 neo01-el64
kernel: svcrdma: processing ctxt=ffff880866754540 on xprt=ffff88087dfa2400, rqstp=ffff88086409a000, status=0 May 19 23:47:02 neo01-el64 kernel: svcrdma: failed to post SQ WR rc=-22, sc_sq_count=0,
sc_sq_depth=128

Quoted 2 lines

May 19 23:47:02 neo01-el64 kernel: svcrdma: Error -22 posting

RDMA_READ

Hey Deevesh,

Looking ocrdma_post_send(),-22 (-EINVAL) is returned when the QP is not in RTS. If the SQ is full, -ENOMEM is returned. So I think the send error is a downstream error because the connection got knocked down. You should try and figure out what kicked the QP out of RTS.

Steve.