[PATCH v2 00/14] NFS/RDMA client side for Linux 4.3

[PATCH v2 00/14] NFS/RDMA client side for Linux 4.3

[Chuck Lever]

Several important client-side performance and scalability
improvements are made in this series, proposed for the 4.3
kernel, including:

- Increase maximum RDMA credits to 128
- Increase maximum NFS r/wsize to one megabyte
- Prefer inline rather than reply chunk replies

And these fixes:

- Send NFSv4 WRITE compounds correctly
- Support RDMA_NOMSG calls
- Fix large NFS symlink operations
- Get inline threshold accounting right

Also available in the "nfs-rdma-for-4.3" topic branch of this git repo:

 git://git.linux-nfs.org/projects/cel/cel-2.6.git

Or for browsing:

 http://git.linux-nfs.org/?p=cel/cel-2.6.git;a=log;h=refs/heads/nfs-rdma-for-4.3


Changes since v1:
 - Rebased on Linux v4.2-rc2
 - PHYSICAL registration, being insecure, must now be explicitly selected
 - Further clean-ups were done because ib_reg_phys_mr() is gone
 - Support for RDMA_MSGP type calls has been removed
 - Some patch descriptions have been clarified

---

Chuck Lever (14):
      xprtrdma: Make xprt_setup_rdma() agnostic to family of server address
      xprtrdma: Raise maximum payload size to one megabyte
      xprtrdma: Increase default credit limit
      xprtrdma: Don't fall back to PHYSICAL memory registration
      xprtrdma: Remove last ib_reg_phys_mr() call site
      xprtrdma: Clean up rpcrdma_ia_open()
      xprtrdma: Remove logic that constructs RDMA_MSGP type calls
      xprtrdma: Account for RPC/RDMA header size when deciding to inline
      xprtrdma: Always provide a write list when sending NFS READ
      xprtrdma: Don't provide a reply chunk when expecting a short reply
      xprtrdma: Fix XDR tail buffer marshalling
      xprtrdma: Fix large NFS SYMLINK calls
      xprtrdma: Clean up xprt_rdma_print_stats()
      xprtrdma: Count RDMA_NOMSG type calls


 fs/nfs/nfs3xdr.c                   |    1 
 fs/nfs/nfs4xdr.c                   |    4 +
 include/linux/sunrpc/xprtrdma.h    |    2 
 net/sunrpc/xprtrdma/fmr_ops.c      |   19 +++
 net/sunrpc/xprtrdma/frwr_ops.c     |    5 +
 net/sunrpc/xprtrdma/physical_ops.c |   25 ++++-
 net/sunrpc/xprtrdma/rpc_rdma.c     |  197 ++++++++++++++++++------------------
 net/sunrpc/xprtrdma/transport.c    |   77 ++++++--------
 net/sunrpc/xprtrdma/verbs.c        |  197 +++++++++---------------------------
 net/sunrpc/xprtrdma/xprt_rdma.h    |   27 ++---
 10 files changed, 252 insertions(+), 302 deletions(-)

--
Chuck Lever

[PATCH v2 01/14] xprtrdma: Make xprt_setup_rdma() agnostic to family of server address

[Chuck Lever]

In particular, recognize when an IPv6 connection is bound.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/transport.c |   28 +++++++++++-----------------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index 680f888..d737300 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -175,10 +175,8 @@ xprt_rdma_format_addresses6(struct rpc_xprt *xprt, struct sockaddr *sap)
 }
 
 static void
-xprt_rdma_format_addresses(struct rpc_xprt *xprt)
+xprt_rdma_format_addresses(struct rpc_xprt *xprt, struct sockaddr *sap)
 {
-	struct sockaddr *sap = (struct sockaddr *)
-					&rpcx_to_rdmad(xprt).addr;
 	char buf[128];
 
 	switch (sap->sa_family) {
@@ -302,7 +300,7 @@ xprt_setup_rdma(struct xprt_create *args)
 	struct rpc_xprt *xprt;
 	struct rpcrdma_xprt *new_xprt;
 	struct rpcrdma_ep *new_ep;
-	struct sockaddr_in *sin;
+	struct sockaddr *sap;
 	int rc;
 
 	if (args->addrlen > sizeof(xprt->addr)) {
@@ -333,26 +331,20 @@ xprt_setup_rdma(struct xprt_create *args)
 	 * Set up RDMA-specific connect data.
 	 */
 
-	/* Put server RDMA address in local cdata */
-	memcpy(&cdata.addr, args->dstaddr, args->addrlen);
+	sap = (struct sockaddr *)&cdata.addr;
+	memcpy(sap, args->dstaddr, args->addrlen);
 
 	/* Ensure xprt->addr holds valid server TCP (not RDMA)
 	 * address, for any side protocols which peek at it */
 	xprt->prot = IPPROTO_TCP;
 	xprt->addrlen = args->addrlen;
-	memcpy(&xprt->addr, &cdata.addr, xprt->addrlen);
+	memcpy(&xprt->addr, sap, xprt->addrlen);
 
-	sin = (struct sockaddr_in *)&cdata.addr;
-	if (ntohs(sin->sin_port) != 0)
+	if (rpc_get_port(sap))
 		xprt_set_bound(xprt);
 
-	dprintk("RPC:       %s: %pI4:%u\n",
-		__func__, &sin->sin_addr.s_addr, ntohs(sin->sin_port));
-
-	/* Set max requests */
 	cdata.max_requests = xprt->max_reqs;
 
-	/* Set some length limits */
 	cdata.rsize = RPCRDMA_MAX_SEGS * PAGE_SIZE; /* RDMA write max */
 	cdata.wsize = RPCRDMA_MAX_SEGS * PAGE_SIZE; /* RDMA read max */
 
@@ -375,8 +367,7 @@ xprt_setup_rdma(struct xprt_create *args)
 
 	new_xprt = rpcx_to_rdmax(xprt);
 
-	rc = rpcrdma_ia_open(new_xprt, (struct sockaddr *) &cdata.addr,
-				xprt_rdma_memreg_strategy);
+	rc = rpcrdma_ia_open(new_xprt, sap, xprt_rdma_memreg_strategy);
 	if (rc)
 		goto out1;
 
@@ -409,7 +400,7 @@ xprt_setup_rdma(struct xprt_create *args)
 	INIT_DELAYED_WORK(&new_xprt->rx_connect_worker,
 			  xprt_rdma_connect_worker);
 
-	xprt_rdma_format_addresses(xprt);
+	xprt_rdma_format_addresses(xprt, sap);
 	xprt->max_payload = new_xprt->rx_ia.ri_ops->ro_maxpages(new_xprt);
 	if (xprt->max_payload == 0)
 		goto out4;
@@ -420,6 +411,9 @@ xprt_setup_rdma(struct xprt_create *args)
 	if (!try_module_get(THIS_MODULE))
 		goto out4;
 
+	dprintk("RPC:       %s: %s:%s\n", __func__,
+		xprt->address_strings[RPC_DISPLAY_ADDR],
+		xprt->address_strings[RPC_DISPLAY_PORT]);
 	return xprt;
 
 out4:

[PATCH v2 02/14] xprtrdma: Raise maximum payload size to one megabyte

[Chuck Lever]

The point of larger rsize and wsize is to reduce the per-byte cost
of memory registration and deregistration. Modern HCAs can typically
handle a megabyte or more with a single registration operation.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Devesh Sharma <devesh.sharma@avagotech.com>
Reviewed-By: Sagi Grimberg <sagig@mellanox.com>
---
 net/sunrpc/xprtrdma/xprt_rdma.h |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index f49dd8b..abee472 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -165,8 +165,7 @@ rdmab_to_msg(struct rpcrdma_regbuf *rb)
  * struct rpcrdma_buffer. N is the max number of outstanding requests.
  */
 
-/* temporary static scatter/gather max */
-#define RPCRDMA_MAX_DATA_SEGS	(64)	/* max scatter/gather */
+#define RPCRDMA_MAX_DATA_SEGS	((1 * 1024 * 1024) / PAGE_SIZE)
 #define RPCRDMA_MAX_SEGS 	(RPCRDMA_MAX_DATA_SEGS + 2) /* head+tail = 2 */
 
 struct rpcrdma_buffer;

[PATCH v2 03/14] xprtrdma: Increase default credit limit

[Chuck Lever]

In preparation for similar increases on NFS/RDMA servers, bump the
advertised credit limit for RPC/RDMA to 128. This allocates some
extra resources, but the client will continue to allow only the
number of RPCs in flight that the server requests via its advertised
credit limit.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-By: Sagi Grimberg <sagig@mellanox.com>
---
 include/linux/sunrpc/xprtrdma.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/sunrpc/xprtrdma.h b/include/linux/sunrpc/xprtrdma.h
index b176130..b7b279b 100644
--- a/include/linux/sunrpc/xprtrdma.h
+++ b/include/linux/sunrpc/xprtrdma.h
@@ -49,7 +49,7 @@
  * a single chunk type per message is supported currently.
  */
 #define RPCRDMA_MIN_SLOT_TABLE	(2U)
-#define RPCRDMA_DEF_SLOT_TABLE	(32U)
+#define RPCRDMA_DEF_SLOT_TABLE	(128U)
 #define RPCRDMA_MAX_SLOT_TABLE	(256U)
 
 #define RPCRDMA_DEF_INLINE  (1024)	/* default inline max */

[PATCH v2 04/14] xprtrdma: Don't fall back to PHYSICAL memory registration

[Chuck Lever]

PHYSICAL memory registration uses a single rkey for all of the
client's memory, thus is insecure. It is still useful in some cases
for testing.

Retain the ability to select PHYSICAL memory registration capability
via /proc/sys/sunrpc/rdma_memreg_strategy, but don't fall back to it
if the HCA does not support FRWR or FMR.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/verbs.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 891c4ed..1065808 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -539,7 +539,7 @@ rpcrdma_ia_open(struct rpcrdma_xprt *xprt, struct sockaddr *addr, int memreg)
 		if (!ia->ri_device->alloc_fmr) {
 			dprintk("RPC:       %s: MTHCAFMR registration "
 				"not supported by HCA\n", __func__);
-			memreg = RPCRDMA_ALLPHYSICAL;
+			goto out3;
 		}
 	}
 

[PATCH v2 05/14] xprtrdma: Remove last ib_reg_phys_mr() call site

[Chuck Lever]

All HCA providers have an ib_get_dma_mr() verb. Thus
rpcrdma_ia_open() will either grab the device's local_dma_key if one
is available, or it will call ib_get_dma_mr() which is a 100%
guaranteed fallback.

There is never any need to use the ib_reg_phys_mr() code path in
rpcrdma_register_internal(), so it can be removed. The remaining
logic in rpcrdma_{de}register_internal() is folded into
rpcrdma_{alloc,free}_regbuf().

This is clean up only. No behavior change is expected.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Devesh Sharma <devesh.sharma@avagotech.com>
Reviewed-By: Sagi Grimberg <sagig@mellanox.com>
---
 net/sunrpc/xprtrdma/verbs.c     |  102 ++++++++-------------------------------
 net/sunrpc/xprtrdma/xprt_rdma.h |    1 
 2 files changed, 21 insertions(+), 82 deletions(-)

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 1065808..da184f9 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -1229,75 +1229,6 @@ rpcrdma_mapping_error(struct rpcrdma_mr_seg *seg)
 		(unsigned long long)seg->mr_dma, seg->mr_dmalen);
 }
 
-static int
-rpcrdma_register_internal(struct rpcrdma_ia *ia, void *va, int len,
-				struct ib_mr **mrp, struct ib_sge *iov)
-{
-	struct ib_phys_buf ipb;
-	struct ib_mr *mr;
-	int rc;
-
-	/*
-	 * All memory passed here was kmalloc'ed, therefore phys-contiguous.
-	 */
-	iov->addr = ib_dma_map_single(ia->ri_device,
-			va, len, DMA_BIDIRECTIONAL);
-	if (ib_dma_mapping_error(ia->ri_device, iov->addr))
-		return -ENOMEM;
-
-	iov->length = len;
-
-	if (ia->ri_have_dma_lkey) {
-		*mrp = NULL;
-		iov->lkey = ia->ri_dma_lkey;
-		return 0;
-	} else if (ia->ri_bind_mem != NULL) {
-		*mrp = NULL;
-		iov->lkey = ia->ri_bind_mem->lkey;
-		return 0;
-	}
-
-	ipb.addr = iov->addr;
-	ipb.size = iov->length;
-	mr = ib_reg_phys_mr(ia->ri_pd, &ipb, 1,
-			IB_ACCESS_LOCAL_WRITE, &iov->addr);
-
-	dprintk("RPC:       %s: phys convert: 0x%llx "
-			"registered 0x%llx length %d\n",
-			__func__, (unsigned long long)ipb.addr,
-			(unsigned long long)iov->addr, len);
-
-	if (IS_ERR(mr)) {
-		*mrp = NULL;
-		rc = PTR_ERR(mr);
-		dprintk("RPC:       %s: failed with %i\n", __func__, rc);
-	} else {
-		*mrp = mr;
-		iov->lkey = mr->lkey;
-		rc = 0;
-	}
-
-	return rc;
-}
-
-static int
-rpcrdma_deregister_internal(struct rpcrdma_ia *ia,
-				struct ib_mr *mr, struct ib_sge *iov)
-{
-	int rc;
-
-	ib_dma_unmap_single(ia->ri_device,
-			    iov->addr, iov->length, DMA_BIDIRECTIONAL);
-
-	if (NULL == mr)
-		return 0;
-
-	rc = ib_dereg_mr(mr);
-	if (rc)
-		dprintk("RPC:       %s: ib_dereg_mr failed %i\n", __func__, rc);
-	return rc;
-}
-
 /**
  * rpcrdma_alloc_regbuf - kmalloc and register memory for SEND/RECV buffers
  * @ia: controlling rpcrdma_ia
@@ -1317,26 +1248,30 @@ struct rpcrdma_regbuf *
 rpcrdma_alloc_regbuf(struct rpcrdma_ia *ia, size_t size, gfp_t flags)
 {
 	struct rpcrdma_regbuf *rb;
-	int rc;
+	struct ib_sge *iov;
 
-	rc = -ENOMEM;
 	rb = kmalloc(sizeof(*rb) + size, flags);
 	if (rb == NULL)
 		goto out;
 
-	rb->rg_size = size;
-	rb->rg_owner = NULL;
-	rc = rpcrdma_register_internal(ia, rb->rg_base, size,
-				       &rb->rg_mr, &rb->rg_iov);
-	if (rc)
+	iov = &rb->rg_iov;
+	iov->addr = ib_dma_map_single(ia->ri_device,
+				      (void *)rb->rg_base, size,
+				      DMA_BIDIRECTIONAL);
+	if (ib_dma_mapping_error(ia->ri_device, iov->addr))
 		goto out_free;
 
+	iov->length = size;
+	iov->lkey = ia->ri_have_dma_lkey ?
+				ia->ri_dma_lkey : ia->ri_bind_mem->lkey;
+	rb->rg_size = size;
+	rb->rg_owner = NULL;
 	return rb;
 
 out_free:
 	kfree(rb);
 out:
-	return ERR_PTR(rc);
+	return ERR_PTR(-ENOMEM);
 }
 
 /**
@@ -1347,10 +1282,15 @@ out:
 void
 rpcrdma_free_regbuf(struct rpcrdma_ia *ia, struct rpcrdma_regbuf *rb)
 {
-	if (rb) {
-		rpcrdma_deregister_internal(ia, rb->rg_mr, &rb->rg_iov);
-		kfree(rb);
-	}
+	struct ib_sge *iov;
+
+	if (!rb)
+		return;
+
+	iov = &rb->rg_iov;
+	ib_dma_unmap_single(ia->ri_device,
+			    iov->addr, iov->length, DMA_BIDIRECTIONAL);
+	kfree(rb);
 }
 
 /*
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index abee472..ce4e79e 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -119,7 +119,6 @@ struct rpcrdma_ep {
 struct rpcrdma_regbuf {
 	size_t			rg_size;
 	struct rpcrdma_req	*rg_owner;
-	struct ib_mr		*rg_mr;
 	struct ib_sge		rg_iov;
 	__be32			rg_base[0] __attribute__ ((aligned(256)));
 };

[PATCH v2 06/14] xprtrdma: Clean up rpcrdma_ia_open()

[Chuck Lever]

Untangle the end of rpcrdma_ia_open() by moving DMA MR set-up, which
is different for each registration method, to the .ro_open functions.

This is refactoring only. No behavior change is expected.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/fmr_ops.c      |   19 +++++++++++
 net/sunrpc/xprtrdma/frwr_ops.c     |    5 +++
 net/sunrpc/xprtrdma/physical_ops.c |   25 ++++++++++++++-
 net/sunrpc/xprtrdma/verbs.c        |   60 +++++++++++-------------------------
 net/sunrpc/xprtrdma/xprt_rdma.h    |    3 +-
 5 files changed, 67 insertions(+), 45 deletions(-)

diff --git a/net/sunrpc/xprtrdma/fmr_ops.c b/net/sunrpc/xprtrdma/fmr_ops.c
index f1e8daf..cb25c89 100644
--- a/net/sunrpc/xprtrdma/fmr_ops.c
+++ b/net/sunrpc/xprtrdma/fmr_ops.c
@@ -39,6 +39,25 @@ static int
 fmr_op_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep,
 	    struct rpcrdma_create_data_internal *cdata)
 {
+	struct ib_device_attr *devattr = &ia->ri_devattr;
+	struct ib_mr *mr;
+
+	/* Obtain an lkey to use for the regbufs, which are
+	 * protected from remote access.
+	 */
+	if (devattr->device_cap_flags & IB_DEVICE_LOCAL_DMA_LKEY) {
+		ia->ri_dma_lkey = ia->ri_device->local_dma_lkey;
+	} else {
+		mr = ib_get_dma_mr(ia->ri_pd, IB_ACCESS_LOCAL_WRITE);
+		if (IS_ERR(mr)) {
+			pr_err("%s: ib_get_dma_mr for failed with %lX\n",
+			       __func__, PTR_ERR(mr));
+			return -ENOMEM;
+		}
+		ia->ri_dma_lkey = ia->ri_dma_mr->lkey;
+		ia->ri_dma_mr = mr;
+	}
+
 	return 0;
 }
 
diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
index 04ea914..63f282e 100644
--- a/net/sunrpc/xprtrdma/frwr_ops.c
+++ b/net/sunrpc/xprtrdma/frwr_ops.c
@@ -189,6 +189,11 @@ frwr_op_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep,
 	struct ib_device_attr *devattr = &ia->ri_devattr;
 	int depth, delta;
 
+	/* Obtain an lkey to use for the regbufs, which are
+	 * protected from remote access.
+	 */
+	ia->ri_dma_lkey = ia->ri_device->local_dma_lkey;
+
 	ia->ri_max_frmr_depth =
 			min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
 			      devattr->max_fast_reg_page_list_len);
diff --git a/net/sunrpc/xprtrdma/physical_ops.c b/net/sunrpc/xprtrdma/physical_ops.c
index 41985d0..72cf8b1 100644
--- a/net/sunrpc/xprtrdma/physical_ops.c
+++ b/net/sunrpc/xprtrdma/physical_ops.c
@@ -23,6 +23,29 @@ static int
 physical_op_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep,
 		 struct rpcrdma_create_data_internal *cdata)
 {
+	struct ib_device_attr *devattr = &ia->ri_devattr;
+	struct ib_mr *mr;
+
+	/* Obtain an rkey to use for RPC data payloads.
+	 */
+	mr = ib_get_dma_mr(ia->ri_pd,
+			   IB_ACCESS_LOCAL_WRITE |
+			   IB_ACCESS_REMOTE_WRITE |
+			   IB_ACCESS_REMOTE_READ);
+	if (IS_ERR(mr)) {
+		pr_err("%s: ib_get_dma_mr for failed with %lX\n",
+		       __func__, PTR_ERR(mr));
+		return -ENOMEM;
+	}
+	ia->ri_dma_mr = mr;
+
+	/* Obtain an lkey to use for regbufs.
+	 */
+	if (devattr->device_cap_flags & IB_DEVICE_LOCAL_DMA_LKEY)
+		ia->ri_dma_lkey = ia->ri_device->local_dma_lkey;
+	else
+		ia->ri_dma_lkey = ia->ri_dma_mr->lkey;
+
 	return 0;
 }
 
@@ -51,7 +74,7 @@ physical_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
 	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
 
 	rpcrdma_map_one(ia->ri_device, seg, rpcrdma_data_dir(writing));
-	seg->mr_rkey = ia->ri_bind_mem->rkey;
+	seg->mr_rkey = ia->ri_dma_mr->rkey;
 	seg->mr_base = seg->mr_dma;
 	seg->mr_nsegs = 1;
 	return 1;
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index da184f9..8516d98 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -493,9 +493,11 @@ rpcrdma_clean_cq(struct ib_cq *cq)
 int
 rpcrdma_ia_open(struct rpcrdma_xprt *xprt, struct sockaddr *addr, int memreg)
 {
-	int rc, mem_priv;
 	struct rpcrdma_ia *ia = &xprt->rx_ia;
 	struct ib_device_attr *devattr = &ia->ri_devattr;
+	int rc;
+
+	ia->ri_dma_mr = NULL;
 
 	ia->ri_id = rpcrdma_create_id(xprt, ia, addr);
 	if (IS_ERR(ia->ri_id)) {
@@ -519,11 +521,6 @@ rpcrdma_ia_open(struct rpcrdma_xprt *xprt, struct sockaddr *addr, int memreg)
 		goto out3;
 	}
 
-	if (devattr->device_cap_flags & IB_DEVICE_LOCAL_DMA_LKEY) {
-		ia->ri_have_dma_lkey = 1;
-		ia->ri_dma_lkey = ia->ri_device->local_dma_lkey;
-	}
-
 	if (memreg == RPCRDMA_FRMR) {
 		/* Requires both frmr reg and local dma lkey */
 		if (((devattr->device_cap_flags &
@@ -543,38 +540,15 @@ rpcrdma_ia_open(struct rpcrdma_xprt *xprt, struct sockaddr *addr, int memreg)
 		}
 	}
 
-	/*
-	 * Optionally obtain an underlying physical identity mapping in
-	 * order to do a memory window-based bind. This base registration
-	 * is protected from remote access - that is enabled only by binding
-	 * for the specific bytes targeted during each RPC operation, and
-	 * revoked after the corresponding completion similar to a storage
-	 * adapter.
-	 */
 	switch (memreg) {
 	case RPCRDMA_FRMR:
 		ia->ri_ops = &rpcrdma_frwr_memreg_ops;
 		break;
 	case RPCRDMA_ALLPHYSICAL:
 		ia->ri_ops = &rpcrdma_physical_memreg_ops;
-		mem_priv = IB_ACCESS_LOCAL_WRITE |
-				IB_ACCESS_REMOTE_WRITE |
-				IB_ACCESS_REMOTE_READ;
-		goto register_setup;
+		break;
 	case RPCRDMA_MTHCAFMR:
 		ia->ri_ops = &rpcrdma_fmr_memreg_ops;
-		if (ia->ri_have_dma_lkey)
-			break;
-		mem_priv = IB_ACCESS_LOCAL_WRITE;
-	register_setup:
-		ia->ri_bind_mem = ib_get_dma_mr(ia->ri_pd, mem_priv);
-		if (IS_ERR(ia->ri_bind_mem)) {
-			printk(KERN_ALERT "%s: ib_get_dma_mr for "
-				"phys register failed with %lX\n",
-				__func__, PTR_ERR(ia->ri_bind_mem));
-			rc = -ENOMEM;
-			goto out3;
-		}
 		break;
 	default:
 		printk(KERN_ERR "RPC: Unsupported memory "
@@ -606,15 +580,7 @@ out1:
 void
 rpcrdma_ia_close(struct rpcrdma_ia *ia)
 {
-	int rc;
-
 	dprintk("RPC:       %s: entering\n", __func__);
-	if (ia->ri_bind_mem != NULL) {
-		rc = ib_dereg_mr(ia->ri_bind_mem);
-		dprintk("RPC:       %s: ib_dereg_mr returned %i\n",
-			__func__, rc);
-	}
-
 	if (ia->ri_id != NULL && !IS_ERR(ia->ri_id)) {
 		if (ia->ri_id->qp)
 			rdma_destroy_qp(ia->ri_id);
@@ -661,8 +627,10 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
 	if (cdata->padding) {
 		ep->rep_padbuf = rpcrdma_alloc_regbuf(ia, cdata->padding,
 						      GFP_KERNEL);
-		if (IS_ERR(ep->rep_padbuf))
-			return PTR_ERR(ep->rep_padbuf);
+		if (IS_ERR(ep->rep_padbuf)) {
+			rc = PTR_ERR(ep->rep_padbuf);
+			goto out0;
+		}
 	} else
 		ep->rep_padbuf = NULL;
 
@@ -749,6 +717,9 @@ out2:
 			__func__, err);
 out1:
 	rpcrdma_free_regbuf(ia, ep->rep_padbuf);
+out0:
+	if (ia->ri_dma_mr)
+		ib_dereg_mr(ia->ri_dma_mr);
 	return rc;
 }
 
@@ -788,6 +759,12 @@ rpcrdma_ep_destroy(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
 	if (rc)
 		dprintk("RPC:       %s: ib_destroy_cq returned %i\n",
 			__func__, rc);
+
+	if (ia->ri_dma_mr) {
+		rc = ib_dereg_mr(ia->ri_dma_mr);
+		dprintk("RPC:       %s: ib_dereg_mr returned %i\n",
+			__func__, rc);
+	}
 }
 
 /*
@@ -1262,8 +1239,7 @@ rpcrdma_alloc_regbuf(struct rpcrdma_ia *ia, size_t size, gfp_t flags)
 		goto out_free;
 
 	iov->length = size;
-	iov->lkey = ia->ri_have_dma_lkey ?
-				ia->ri_dma_lkey : ia->ri_bind_mem->lkey;
+	iov->lkey = ia->ri_dma_lkey;
 	rb->rg_size = size;
 	rb->rg_owner = NULL;
 	return rb;
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index ce4e79e..8219011 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -65,9 +65,8 @@ struct rpcrdma_ia {
 	struct ib_device	*ri_device;
 	struct rdma_cm_id 	*ri_id;
 	struct ib_pd		*ri_pd;
-	struct ib_mr		*ri_bind_mem;
+	struct ib_mr		*ri_dma_mr;
 	u32			ri_dma_lkey;
-	int			ri_have_dma_lkey;
 	struct completion	ri_done;
 	int			ri_async_rc;
 	unsigned int		ri_max_frmr_depth;

[PATCH v2 07/14] xprtrdma: Remove logic that constructs RDMA_MSGP type calls

[Chuck Lever]

RDMA_MSGP type calls insert a zero pad in the middle of the RPC
message to align the RPC request's data payload to the server's
alignment preferences. A server can then "page flip" the payload
into place to avoid a data copy in certain circumstances. However:

1. The client has to have a priori knowledge of the server's
   preferred alignment

2. Requests eligible for RDMA_MSGP are requests that are small
   enough to have been sent inline, and convey a data payload
   at the _end_ of the RPC message

Today 1. is done with a sysctl, and is a global setting that is
copied during mount. Linux does not support CCP to query the
server's preferences (RFC 5666, Section 6).

A small-ish NFSv3 WRITE might use RDMA_MSGP, but no NFSv4
compound fits bullet 2.

Thus the Linux client currently leaves RDMA_MSGP disabled. The
Linux server handles RDMA_MSGP, but does not use any special
page flipping, so it confers no benefit.

Clean up the marshaling code by removing the logic that constructs
RDMA_MSGP type calls. This also reduces the maximum send iovec size
from four to just two elements.

/proc/sys/sunrpc/rdma_inline_write_padding is a kernel API, and
thus is left in place.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/rpc_rdma.c  |   92 ++++++++++-----------------------------
 net/sunrpc/xprtrdma/verbs.c     |   47 +++++++-------------
 net/sunrpc/xprtrdma/xprt_rdma.h |   19 ++++----
 3 files changed, 51 insertions(+), 107 deletions(-)

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 84ea37d..8e9c564 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -297,8 +297,7 @@ out:
  * pre-registered memory buffer for this request. For small amounts
  * of data, this is efficient. The cutoff value is tunable.
  */
-static int
-rpcrdma_inline_pullup(struct rpc_rqst *rqst, int pad)
+static void rpcrdma_inline_pullup(struct rpc_rqst *rqst)
 {
 	int i, npages, curlen;
 	int copy_len;
@@ -310,16 +309,9 @@ rpcrdma_inline_pullup(struct rpc_rqst *rqst, int pad)
 	destp = rqst->rq_svec[0].iov_base;
 	curlen = rqst->rq_svec[0].iov_len;
 	destp += curlen;
-	/*
-	 * Do optional padding where it makes sense. Alignment of write
-	 * payload can help the server, if our setting is accurate.
-	 */
-	pad -= (curlen + 36/*sizeof(struct rpcrdma_msg_padded)*/);
-	if (pad < 0 || rqst->rq_slen - curlen < RPCRDMA_INLINE_PAD_THRESH)
-		pad = 0;	/* don't pad this request */
 
-	dprintk("RPC:       %s: pad %d destp 0x%p len %d hdrlen %d\n",
-		__func__, pad, destp, rqst->rq_slen, curlen);
+	dprintk("RPC:       %s: destp 0x%p len %d hdrlen %d\n",
+		__func__, destp, rqst->rq_slen, curlen);
 
 	copy_len = rqst->rq_snd_buf.page_len;
 
@@ -355,7 +347,6 @@ rpcrdma_inline_pullup(struct rpc_rqst *rqst, int pad)
 		page_base = 0;
 	}
 	/* header now contains entire send message */
-	return pad;
 }
 
 /*
@@ -380,7 +371,7 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
 	struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
 	char *base;
-	size_t rpclen, padlen;
+	size_t rpclen;
 	ssize_t hdrlen;
 	enum rpcrdma_chunktype rtype, wtype;
 	struct rpcrdma_msg *headerp;
@@ -458,7 +449,6 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	}
 
 	hdrlen = RPCRDMA_HDRLEN_MIN;
-	padlen = 0;
 
 	/*
 	 * Pull up any extra send data into the preregistered buffer.
@@ -467,43 +457,24 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	 */
 	if (rtype == rpcrdma_noch) {
 
-		padlen = rpcrdma_inline_pullup(rqst,
-						RPCRDMA_INLINE_PAD_VALUE(rqst));
-
-		if (padlen) {
-			headerp->rm_type = rdma_msgp;
-			headerp->rm_body.rm_padded.rm_align =
-				cpu_to_be32(RPCRDMA_INLINE_PAD_VALUE(rqst));
-			headerp->rm_body.rm_padded.rm_thresh =
-				cpu_to_be32(RPCRDMA_INLINE_PAD_THRESH);
-			headerp->rm_body.rm_padded.rm_pempty[0] = xdr_zero;
-			headerp->rm_body.rm_padded.rm_pempty[1] = xdr_zero;
-			headerp->rm_body.rm_padded.rm_pempty[2] = xdr_zero;
-			hdrlen += 2 * sizeof(u32); /* extra words in padhdr */
-			if (wtype != rpcrdma_noch) {
-				dprintk("RPC:       %s: invalid chunk list\n",
-					__func__);
-				return -EIO;
-			}
-		} else {
-			headerp->rm_body.rm_nochunks.rm_empty[0] = xdr_zero;
-			headerp->rm_body.rm_nochunks.rm_empty[1] = xdr_zero;
-			headerp->rm_body.rm_nochunks.rm_empty[2] = xdr_zero;
-			/* new length after pullup */
-			rpclen = rqst->rq_svec[0].iov_len;
-			/*
-			 * Currently we try to not actually use read inline.
-			 * Reply chunks have the desirable property that
-			 * they land, packed, directly in the target buffers
-			 * without headers, so they require no fixup. The
-			 * additional RDMA Write op sends the same amount
-			 * of data, streams on-the-wire and adds no overhead
-			 * on receive. Therefore, we request a reply chunk
-			 * for non-writes wherever feasible and efficient.
-			 */
-			if (wtype == rpcrdma_noch)
-				wtype = rpcrdma_replych;
-		}
+		rpcrdma_inline_pullup(rqst);
+
+		headerp->rm_body.rm_nochunks.rm_empty[0] = xdr_zero;
+		headerp->rm_body.rm_nochunks.rm_empty[1] = xdr_zero;
+		headerp->rm_body.rm_nochunks.rm_empty[2] = xdr_zero;
+		/* new length after pullup */
+		rpclen = rqst->rq_svec[0].iov_len;
+		/* Currently we try to not actually use read inline.
+		 * Reply chunks have the desirable property that
+		 * they land, packed, directly in the target buffers
+		 * without headers, so they require no fixup. The
+		 * additional RDMA Write op sends the same amount
+		 * of data, streams on-the-wire and adds no overhead
+		 * on receive. Therefore, we request a reply chunk
+		 * for non-writes wherever feasible and efficient.
+		 */
+		if (wtype == rpcrdma_noch)
+			wtype = rpcrdma_replych;
 	}
 
 	if (rtype != rpcrdma_noch) {
@@ -518,9 +489,9 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	if (hdrlen < 0)
 		return hdrlen;
 
-	dprintk("RPC:       %s: %s: hdrlen %zd rpclen %zd padlen %zd"
+	dprintk("RPC:       %s: %s: hdrlen %zd rpclen %zd"
 		" headerp 0x%p base 0x%p lkey 0x%x\n",
-		__func__, transfertypes[wtype], hdrlen, rpclen, padlen,
+		__func__, transfertypes[wtype], hdrlen, rpclen,
 		headerp, base, rdmab_lkey(req->rl_rdmabuf));
 
 	/*
@@ -539,21 +510,6 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	req->rl_send_iov[1].lkey = rdmab_lkey(req->rl_sendbuf);
 
 	req->rl_niovs = 2;
-
-	if (padlen) {
-		struct rpcrdma_ep *ep = &r_xprt->rx_ep;
-
-		req->rl_send_iov[2].addr = rdmab_addr(ep->rep_padbuf);
-		req->rl_send_iov[2].length = padlen;
-		req->rl_send_iov[2].lkey = rdmab_lkey(ep->rep_padbuf);
-
-		req->rl_send_iov[3].addr = req->rl_send_iov[1].addr + rpclen;
-		req->rl_send_iov[3].length = rqst->rq_slen - rpclen;
-		req->rl_send_iov[3].lkey = rdmab_lkey(req->rl_sendbuf);
-
-		req->rl_niovs = 4;
-	}
-
 	return 0;
 }
 
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 8516d98..b4d4f63 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -605,6 +605,12 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
 	struct ib_cq_init_attr cq_attr = {};
 	int rc, err;
 
+	if (devattr->max_sge < RPCRDMA_MAX_IOVS) {
+		dprintk("RPC:       %s: insufficient sge's available\n",
+			__func__);
+		return -ENOMEM;
+	}
+
 	/* check provider's send/recv wr limits */
 	if (cdata->max_requests > devattr->max_qp_wr)
 		cdata->max_requests = devattr->max_qp_wr;
@@ -617,23 +623,13 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
 	if (rc)
 		return rc;
 	ep->rep_attr.cap.max_recv_wr = cdata->max_requests;
-	ep->rep_attr.cap.max_send_sge = (cdata->padding ? 4 : 2);
+	ep->rep_attr.cap.max_send_sge = RPCRDMA_MAX_IOVS;
 	ep->rep_attr.cap.max_recv_sge = 1;
 	ep->rep_attr.cap.max_inline_data = 0;
 	ep->rep_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
 	ep->rep_attr.qp_type = IB_QPT_RC;
 	ep->rep_attr.port_num = ~0;
 
-	if (cdata->padding) {
-		ep->rep_padbuf = rpcrdma_alloc_regbuf(ia, cdata->padding,
-						      GFP_KERNEL);
-		if (IS_ERR(ep->rep_padbuf)) {
-			rc = PTR_ERR(ep->rep_padbuf);
-			goto out0;
-		}
-	} else
-		ep->rep_padbuf = NULL;
-
 	dprintk("RPC:       %s: requested max: dtos: send %d recv %d; "
 		"iovs: send %d recv %d\n",
 		__func__,
@@ -716,8 +712,6 @@ out2:
 		dprintk("RPC:       %s: ib_destroy_cq returned %i\n",
 			__func__, err);
 out1:
-	rpcrdma_free_regbuf(ia, ep->rep_padbuf);
-out0:
 	if (ia->ri_dma_mr)
 		ib_dereg_mr(ia->ri_dma_mr);
 	return rc;
@@ -746,8 +740,6 @@ rpcrdma_ep_destroy(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
 		ia->ri_id->qp = NULL;
 	}
 
-	rpcrdma_free_regbuf(ia, ep->rep_padbuf);
-
 	rpcrdma_clean_cq(ep->rep_attr.recv_cq);
 	rc = ib_destroy_cq(ep->rep_attr.recv_cq);
 	if (rc)
@@ -1279,9 +1271,11 @@ rpcrdma_ep_post(struct rpcrdma_ia *ia,
 		struct rpcrdma_ep *ep,
 		struct rpcrdma_req *req)
 {
+	struct ib_device *device = ia->ri_device;
 	struct ib_send_wr send_wr, *send_wr_fail;
 	struct rpcrdma_rep *rep = req->rl_reply;
-	int rc;
+	struct ib_sge *iov = req->rl_send_iov;
+	int i, rc;
 
 	if (rep) {
 		rc = rpcrdma_ep_post_recv(ia, ep, rep);
@@ -1292,22 +1286,15 @@ rpcrdma_ep_post(struct rpcrdma_ia *ia,
 
 	send_wr.next = NULL;
 	send_wr.wr_id = RPCRDMA_IGNORE_COMPLETION;
-	send_wr.sg_list = req->rl_send_iov;
+	send_wr.sg_list = iov;
 	send_wr.num_sge = req->rl_niovs;
 	send_wr.opcode = IB_WR_SEND;
-	if (send_wr.num_sge == 4)	/* no need to sync any pad (constant) */
-		ib_dma_sync_single_for_device(ia->ri_device,
-					      req->rl_send_iov[3].addr,
-					      req->rl_send_iov[3].length,
-					      DMA_TO_DEVICE);
-	ib_dma_sync_single_for_device(ia->ri_device,
-				      req->rl_send_iov[1].addr,
-				      req->rl_send_iov[1].length,
-				      DMA_TO_DEVICE);
-	ib_dma_sync_single_for_device(ia->ri_device,
-				      req->rl_send_iov[0].addr,
-				      req->rl_send_iov[0].length,
-				      DMA_TO_DEVICE);
+
+	for (i = 0; i < send_wr.num_sge; i++)
+		ib_dma_sync_single_for_device(device, iov[i].addr,
+					      iov[i].length, DMA_TO_DEVICE);
+	dprintk("RPC:       %s: posting %d s/g entries\n",
+		__func__, send_wr.num_sge);
 
 	if (DECR_CQCOUNT(ep) > 0)
 		send_wr.send_flags = 0;
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 8219011..0b50103 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -88,7 +88,6 @@ struct rpcrdma_ep {
 	int			rep_connected;
 	struct ib_qp_init_attr	rep_attr;
 	wait_queue_head_t 	rep_connect_wait;
-	struct rpcrdma_regbuf	*rep_padbuf;
 	struct rdma_conn_param	rep_remote_cma;
 	struct sockaddr_storage	rep_remote_addr;
 	struct delayed_work	rep_connect_worker;
@@ -255,16 +254,18 @@ struct rpcrdma_mr_seg {		/* chunk descriptors */
 	char		*mr_offset;	/* kva if no page, else offset */
 };
 
+#define RPCRDMA_MAX_IOVS	(4)
+
 struct rpcrdma_req {
-	unsigned int	rl_niovs;	/* 0, 2 or 4 */
-	unsigned int	rl_nchunks;	/* non-zero if chunks */
-	unsigned int	rl_connect_cookie;	/* retry detection */
-	struct rpcrdma_buffer *rl_buffer; /* home base for this structure */
+	unsigned int		rl_niovs;
+	unsigned int		rl_nchunks;
+	unsigned int		rl_connect_cookie;
+	struct rpcrdma_buffer	*rl_buffer;
 	struct rpcrdma_rep	*rl_reply;/* holder for reply buffer */
-	struct ib_sge	rl_send_iov[4];	/* for active requests */
-	struct rpcrdma_regbuf *rl_rdmabuf;
-	struct rpcrdma_regbuf *rl_sendbuf;
-	struct rpcrdma_mr_seg rl_segments[RPCRDMA_MAX_SEGS];
+	struct ib_sge		rl_send_iov[RPCRDMA_MAX_IOVS];
+	struct rpcrdma_regbuf	*rl_rdmabuf;
+	struct rpcrdma_regbuf	*rl_sendbuf;
+	struct rpcrdma_mr_seg	rl_segments[RPCRDMA_MAX_SEGS];
 };
 
 static inline struct rpcrdma_req *

Re: [PATCH v2 07/14] xprtrdma: Remove logic that constructs RDMA_MSGP type calls

[Tom Talpey]

On 7/13/2015 12:30 PM, Chuck Lever wrote:
> RDMA_MSGP type calls insert a zero pad in the middle of the RPC
> message to align the RPC request's data payload to the server's
> alignment preferences. A server can then "page flip" the payload
> into place to avoid a data copy in certain circumstances. However:
>...
>
> Clean up the marshaling code by removing the logic that constructs
> RDMA_MSGP type calls. This also reduces the maximum send iovec size
> from four to just two elements.
>

> diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
> index 8219011..0b50103 100644
> --- a/net/sunrpc/xprtrdma/xprt_rdma.h
> +++ b/net/sunrpc/xprtrdma/xprt_rdma.h
...>
> +#define RPCRDMA_MAX_IOVS	(4)
> +

So, shouldn't this constant be "2"? The extra 2 iov's were used
only for constructing the pad.

Re: [PATCH v2 07/14] xprtrdma: Remove logic that constructs RDMA_MSGP type calls

[Chuck Lever]

On Jul 14, 2015, at 3:00 PM, Tom Talpey <tom@talpey.com> wrote:

> On 7/13/2015 12:30 PM, Chuck Lever wrote:
>> RDMA_MSGP type calls insert a zero pad in the middle of the RPC
>> message to align the RPC request's data payload to the server's
>> alignment preferences. A server can then "page flip" the payload
>> into place to avoid a data copy in certain circumstances. However:
>> ...
>> 
>> Clean up the marshaling code by removing the logic that constructs
>> RDMA_MSGP type calls. This also reduces the maximum send iovec size
>> from four to just two elements.
>> 
> 
>> diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
>> index 8219011..0b50103 100644
>> --- a/net/sunrpc/xprtrdma/xprt_rdma.h
>> +++ b/net/sunrpc/xprtrdma/xprt_rdma.h
> ...>
>> +#define RPCRDMA_MAX_IOVS	(4)
>> +
> 
> So, shouldn't this constant be "2"? The extra 2 iov's were used
> only for constructing the pad.

Yes, thanks. I folded a couple of patches together into this
one, and forgot to update the constant.


--
Chuck Lever

Re: [PATCH v2 07/14] xprtrdma: Remove logic that constructs RDMA_MSGP type calls

[Devesh Sharma]

with MAX_IOVS set to 2 iozone passes with ocrdma device. My testing
includes both the series of svcrdma and xprtrdma.

On Wed, Jul 15, 2015 at 12:31 AM, Chuck Lever <chuck.lever@oracle.com> wrote:
>
> On Jul 14, 2015, at 3:00 PM, Tom Talpey <tom@talpey.com> wrote:
>
>> On 7/13/2015 12:30 PM, Chuck Lever wrote:
>>> RDMA_MSGP type calls insert a zero pad in the middle of the RPC
>>> message to align the RPC request's data payload to the server's
>>> alignment preferences. A server can then "page flip" the payload
>>> into place to avoid a data copy in certain circumstances. However:
>>> ...
>>>
>>> Clean up the marshaling code by removing the logic that constructs
>>> RDMA_MSGP type calls. This also reduces the maximum send iovec size
>>> from four to just two elements.
>>>
>>
>>> diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
>>> index 8219011..0b50103 100644
>>> --- a/net/sunrpc/xprtrdma/xprt_rdma.h
>>> +++ b/net/sunrpc/xprtrdma/xprt_rdma.h
>> ...>
>>> +#define RPCRDMA_MAX_IOVS    (4)
>>> +
>>
>> So, shouldn't this constant be "2"? The extra 2 iov's were used
>> only for constructing the pad.
>
> Yes, thanks. I folded a couple of patches together into this
> one, and forgot to update the constant.
>
>
> --
> Chuck Lever
>
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
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Re: [PATCH v2 07/14] xprtrdma: Remove logic that constructs RDMA_MSGP type calls

[Chuck Lever]

Thanks Devesh, will note that in the next versions of these series.


On Jul 15, 2015, at 2:26 PM, Devesh Sharma <devesh.sharma@avagotech.com> wrote:

> with MAX_IOVS set to 2 iozone passes with ocrdma device. My testing
> includes both the series of svcrdma and xprtrdma.
> 
> On Wed, Jul 15, 2015 at 12:31 AM, Chuck Lever <chuck.lever@oracle.com> wrote:
>> 
>> On Jul 14, 2015, at 3:00 PM, Tom Talpey <tom@talpey.com> wrote:
>> 
>>> On 7/13/2015 12:30 PM, Chuck Lever wrote:
>>>> RDMA_MSGP type calls insert a zero pad in the middle of the RPC
>>>> message to align the RPC request's data payload to the server's
>>>> alignment preferences. A server can then "page flip" the payload
>>>> into place to avoid a data copy in certain circumstances. However:
>>>> ...
>>>> 
>>>> Clean up the marshaling code by removing the logic that constructs
>>>> RDMA_MSGP type calls. This also reduces the maximum send iovec size
>>>> from four to just two elements.
>>>> 
>>> 
>>>> diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
>>>> index 8219011..0b50103 100644
>>>> --- a/net/sunrpc/xprtrdma/xprt_rdma.h
>>>> +++ b/net/sunrpc/xprtrdma/xprt_rdma.h
>>> ...>
>>>> +#define RPCRDMA_MAX_IOVS    (4)
>>>> +
>>> 
>>> So, shouldn't this constant be "2"? The extra 2 iov's were used
>>> only for constructing the pad.
>> 
>> Yes, thanks. I folded a couple of patches together into this
>> one, and forgot to update the constant.
>> 
>> 
>> --
>> Chuck Lever
>> 
>> 
>> 
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
>> the body of a message to majordomo@vger.kernel.org
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--
Chuck Lever

[PATCH v2 08/14] xprtrdma: Account for RPC/RDMA header size when deciding to inline

[Chuck Lever]

When the size of the RPC message is near the inline threshold (1KB),
the client would allow messages to be sent that were a few bytes too
large.

When marshaling RPC/RDMA requests, ensure the combined size of
RPC/RDMA header and RPC header do not exceed the inline threshold.
Endpoints typically reject RPC/RDMA messages that exceed the size
of their receive buffers.

The two server implementations I test with (Linux and Solaris) use
receive buffers that are larger than the client’s inline threshold.
Thus so far this has been benign, observed only by code inspection.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Devesh Sharma <devesh.sharma@avagotech.com>
---
 net/sunrpc/xprtrdma/rpc_rdma.c |   29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 8e9c564..950b654 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -71,6 +71,31 @@ static const char transfertypes[][12] = {
 };
 #endif
 
+/* The client can send a request inline as long as the RPCRDMA header
+ * plus the RPC call fit under the transport's inline limit. If the
+ * combined call message size exceeds that limit, the client must use
+ * the read chunk list for this operation.
+ */
+static bool rpcrdma_args_inline(struct rpc_rqst *rqst)
+{
+	unsigned int callsize = RPCRDMA_HDRLEN_MIN + rqst->rq_snd_buf.len;
+
+	return callsize <= RPCRDMA_INLINE_WRITE_THRESHOLD(rqst);
+}
+
+/* The client can't know how large the actual reply will be. Thus it
+ * plans for the largest possible reply for that particular ULP
+ * operation. If the maximum combined reply message size exceeds that
+ * limit, the client must provide a write list or a reply chunk for
+ * this request.
+ */
+static bool rpcrdma_results_inline(struct rpc_rqst *rqst)
+{
+	unsigned int repsize = RPCRDMA_HDRLEN_MIN + rqst->rq_rcv_buf.buflen;
+
+	return repsize <= RPCRDMA_INLINE_READ_THRESHOLD(rqst);
+}
+
 /*
  * Chunk assembly from upper layer xdr_buf.
  *
@@ -409,7 +434,7 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	 * a READ, then use write chunks to separate the file data
 	 * into pages; otherwise use reply chunks.
 	 */
-	if (rqst->rq_rcv_buf.buflen <= RPCRDMA_INLINE_READ_THRESHOLD(rqst))
+	if (rpcrdma_results_inline(rqst))
 		wtype = rpcrdma_noch;
 	else if (rqst->rq_rcv_buf.page_len == 0)
 		wtype = rpcrdma_replych;
@@ -432,7 +457,7 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	 * implies the op is a write.
 	 * TBD check NFSv4 setacl
 	 */
-	if (rqst->rq_snd_buf.len <= RPCRDMA_INLINE_WRITE_THRESHOLD(rqst))
+	if (rpcrdma_args_inline(rqst))
 		rtype = rpcrdma_noch;
 	else if (rqst->rq_snd_buf.page_len == 0)
 		rtype = rpcrdma_areadch;

[PATCH v2 09/14] xprtrdma: Always provide a write list when sending NFS READ

[Chuck Lever]

The client has been setting up a reply chunk for NFS READs that are
smaller than the inline threshold. This is not efficient: both the
server and client CPUs have to copy the reply's data payload into
and out of the memory region that is then transferred via RDMA.

Using the write list, the data payload is moved by the device and no
extra data copying is necessary.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Devesh Sharma <devesh.sharma@avagotech.com>
Reviewed-By: Sagi Grimberg <sagig@mellanox.com>
---
 net/sunrpc/xprtrdma/rpc_rdma.c |   21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 950b654..e7cf976 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -418,28 +418,15 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	/*
 	 * Chunks needed for results?
 	 *
+	 * o Read ops return data as write chunk(s), header as inline.
 	 * o If the expected result is under the inline threshold, all ops
 	 *   return as inline (but see later).
 	 * o Large non-read ops return as a single reply chunk.
-	 * o Large read ops return data as write chunk(s), header as inline.
-	 *
-	 * Note: the NFS code sending down multiple result segments implies
-	 * the op is one of read, readdir[plus], readlink or NFSv4 getacl.
-	 */
-
-	/*
-	 * This code can handle read chunks, write chunks OR reply
-	 * chunks -- only one type. If the request is too big to fit
-	 * inline, then we will choose read chunks. If the request is
-	 * a READ, then use write chunks to separate the file data
-	 * into pages; otherwise use reply chunks.
 	 */
-	if (rpcrdma_results_inline(rqst))
-		wtype = rpcrdma_noch;
-	else if (rqst->rq_rcv_buf.page_len == 0)
-		wtype = rpcrdma_replych;
-	else if (rqst->rq_rcv_buf.flags & XDRBUF_READ)
+	if (rqst->rq_rcv_buf.flags & XDRBUF_READ)
 		wtype = rpcrdma_writech;
+	else if (rpcrdma_results_inline(rqst))
+		wtype = rpcrdma_noch;
 	else
 		wtype = rpcrdma_replych;
 

[PATCH v2 10/14] xprtrdma: Don't provide a reply chunk when expecting a short reply

[Chuck Lever]

Currently Linux always offers a reply chunk, even when the reply
can be sent inline (ie. is smaller than 1KB).

On the client, registering a memory region can be expensive. A
server may choose not to use the reply chunk, wasting the cost of
the registration.

This is a change only for RPC replies smaller than 1KB which the
server constructs in the RPC reply send buffer. Because the elements
of the reply must be XDR encoded, a copy-free data transfer has no
benefit in this case.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/rpc_rdma.c |   13 +------------
 1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index e7cf976..62150ae 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -420,7 +420,7 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	 *
 	 * o Read ops return data as write chunk(s), header as inline.
 	 * o If the expected result is under the inline threshold, all ops
-	 *   return as inline (but see later).
+	 *   return as inline.
 	 * o Large non-read ops return as a single reply chunk.
 	 */
 	if (rqst->rq_rcv_buf.flags & XDRBUF_READ)
@@ -476,17 +476,6 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 		headerp->rm_body.rm_nochunks.rm_empty[2] = xdr_zero;
 		/* new length after pullup */
 		rpclen = rqst->rq_svec[0].iov_len;
-		/* Currently we try to not actually use read inline.
-		 * Reply chunks have the desirable property that
-		 * they land, packed, directly in the target buffers
-		 * without headers, so they require no fixup. The
-		 * additional RDMA Write op sends the same amount
-		 * of data, streams on-the-wire and adds no overhead
-		 * on receive. Therefore, we request a reply chunk
-		 * for non-writes wherever feasible and efficient.
-		 */
-		if (wtype == rpcrdma_noch)
-			wtype = rpcrdma_replych;
 	}
 
 	if (rtype != rpcrdma_noch) {

[PATCH v2 11/14] xprtrdma: Fix XDR tail buffer marshalling

[Chuck Lever]

Currently xprtrdma appends an extra chunk element to the RPC/RDMA
read chunk list of each NFSv4 WRITE compound. The extra element
contains the final GETATTR operation in the compound.

The result is an extra RDMA READ operation to transfer a very short
piece of each NFS WRITE compound (typically 16 bytes). This is
inefficient.

It is also incorrect. Although RFC 5667 is not precise about when
using a read list with NFSv4 COMPOUND is allowed, the intent is that
only data arguments not touched by NFS (ie, read and write payloads)
are to be sent using RDMA READ or WRITE. The NFS client constructs
GETATTR arguments itself, and therefore is required to send the
trailing GETATTR operation as additional inline content, not as a
data payload.

NB: This change is not backwards compatible. Some older servers do
not accept inline content following the read list. The Linux NFS
server should handle this content correctly as of commit
a97c331f9aa9 ("svcrdma: Handle additional inline content").

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/rpc_rdma.c |   44 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 42 insertions(+), 2 deletions(-)

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 62150ae..1dd48f2 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -96,6 +96,42 @@ static bool rpcrdma_results_inline(struct rpc_rqst *rqst)
 	return repsize <= RPCRDMA_INLINE_READ_THRESHOLD(rqst);
 }
 
+static int
+rpcrdma_tail_pullup(struct xdr_buf *buf)
+{
+	size_t tlen = buf->tail[0].iov_len;
+	size_t skip = tlen & 3;
+
+	/* Do not include the tail if it is only an XDR pad */
+	if (tlen < 4)
+		return 0;
+
+	/* xdr_write_pages() adds a pad at the beginning of the tail
+	 * if the content in "buf->pages" is unaligned. Force the
+	 * tail's actual content to land at the next XDR position
+	 * after the head instead.
+	 */
+	if (skip) {
+		unsigned char *src, *dst;
+		unsigned int count;
+
+		src = buf->tail[0].iov_base;
+		dst = buf->head[0].iov_base;
+		dst += buf->head[0].iov_len;
+
+		src += skip;
+		tlen -= skip;
+
+		dprintk("RPC:       %s: skip=%zu, memmove(%p, %p, %zu)\n",
+			__func__, skip, dst, src, tlen);
+
+		for (count = tlen; count; count--)
+			*dst++ = *src++;
+	}
+
+	return tlen;
+}
+
 /*
  * Chunk assembly from upper layer xdr_buf.
  *
@@ -147,6 +183,10 @@ rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
 	if (len && n == nsegs)
 		return -EIO;
 
+	/* When encoding the read list, the tail is always sent inline */
+	if (type == rpcrdma_readch)
+		return n;
+
 	if (xdrbuf->tail[0].iov_len) {
 		/* the rpcrdma protocol allows us to omit any trailing
 		 * xdr pad bytes, saving the server an RDMA operation. */
@@ -476,8 +516,8 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 		headerp->rm_body.rm_nochunks.rm_empty[2] = xdr_zero;
 		/* new length after pullup */
 		rpclen = rqst->rq_svec[0].iov_len;
-	}
-
+	} else if (rtype == rpcrdma_readch)
+		rpclen += rpcrdma_tail_pullup(&rqst->rq_snd_buf);
 	if (rtype != rpcrdma_noch) {
 		hdrlen = rpcrdma_create_chunks(rqst, &rqst->rq_snd_buf,
 					       headerp, rtype);

[PATCH v2 12/14] xprtrdma: Fix large NFS SYMLINK calls

[Chuck Lever]

Repair how rpcrdma_marshal_req() chooses which RDMA message type
to use for large non-WRITE operations so that it picks RDMA_NOMSG
in the correct situations, and sets up the marshaling logic to
SEND only the RPC/RDMA header.

Large NFSv2 SYMLINK requests now use RDMA_NOMSG calls. The Linux NFS
server XDR decoder for NFSv2 SYMLINK does not handle having the
pathname argument arrive in a separate buffer. The decoder could be
fixed, but this is simpler and RDMA_NOMSG can be used in a variety
of other situations.

Ensure that the Linux client continues to use "RDMA_MSG + read
list" when sending large NFSv3 SYMLINK requests, which is more
efficient than using RDMA_NOMSG.

Large NFSv4 CREATE(NF4LNK) requests are changed to use "RDMA_MSG +
read list" just like NFSv3 (see Section 5 of RFC 5667). Before,
these did not work at all.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfs/nfs3xdr.c               |    1 +
 fs/nfs/nfs4xdr.c               |    4 +++-
 net/sunrpc/xprtrdma/rpc_rdma.c |   25 ++++++++++++++++---------
 3 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
index 9b04c2e..267126d 100644
--- a/fs/nfs/nfs3xdr.c
+++ b/fs/nfs/nfs3xdr.c
@@ -1103,6 +1103,7 @@ static void nfs3_xdr_enc_symlink3args(struct rpc_rqst *req,
 {
 	encode_diropargs3(xdr, args->fromfh, args->fromname, args->fromlen);
 	encode_symlinkdata3(xdr, args);
+	xdr->buf->flags |= XDRBUF_WRITE;
 }
 
 /*
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 558cd65d..c42459e 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -1154,7 +1154,9 @@ static void encode_create(struct xdr_stream *xdr, const struct nfs4_create_arg *
 	case NF4LNK:
 		p = reserve_space(xdr, 4);
 		*p = cpu_to_be32(create->u.symlink.len);
-		xdr_write_pages(xdr, create->u.symlink.pages, 0, create->u.symlink.len);
+		xdr_write_pages(xdr, create->u.symlink.pages, 0,
+				create->u.symlink.len);
+		xdr->buf->flags |= XDRBUF_WRITE;
 		break;
 
 	case NF4BLK: case NF4CHR:
diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 1dd48f2..2721586 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -475,21 +475,24 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	 *
 	 * o If the total request is under the inline threshold, all ops
 	 *   are sent as inline.
-	 * o Large non-write ops are sent with the entire message as a
-	 *   single read chunk (protocol 0-position special case).
 	 * o Large write ops transmit data as read chunk(s), header as
 	 *   inline.
+	 * o Large non-write ops are sent with the entire message as a
+	 *   single read chunk (protocol 0-position special case).
 	 *
-	 * Note: the NFS code sending down multiple argument segments
-	 * implies the op is a write.
-	 * TBD check NFSv4 setacl
+	 * This assumes that the upper layer does not present a request
+	 * that both has a data payload, and whose non-data arguments
+	 * by themselves are larger than the inline threshold.
 	 */
-	if (rpcrdma_args_inline(rqst))
+	if (rpcrdma_args_inline(rqst)) {
 		rtype = rpcrdma_noch;
-	else if (rqst->rq_snd_buf.page_len == 0)
-		rtype = rpcrdma_areadch;
-	else
+	} else if (rqst->rq_snd_buf.flags & XDRBUF_WRITE) {
 		rtype = rpcrdma_readch;
+	} else {
+		headerp->rm_type = htonl(RDMA_NOMSG);
+		rtype = rpcrdma_areadch;
+		rpclen = 0;
+	}
 
 	/* The following simplification is not true forever */
 	if (rtype != rpcrdma_noch && wtype == rpcrdma_replych)
@@ -546,6 +549,10 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	req->rl_send_iov[0].length = hdrlen;
 	req->rl_send_iov[0].lkey = rdmab_lkey(req->rl_rdmabuf);
 
+	req->rl_niovs = 1;
+	if (rtype == rpcrdma_areadch)
+		return 0;
+
 	req->rl_send_iov[1].addr = rdmab_addr(req->rl_sendbuf);
 	req->rl_send_iov[1].length = rpclen;
 	req->rl_send_iov[1].lkey = rdmab_lkey(req->rl_sendbuf);

[PATCH v2 13/14] xprtrdma: Clean up xprt_rdma_print_stats()

[Chuck Lever]

checkpatch.pl complained about the seq_printf() format string split
across lines and the use of %Lu.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/transport.c |   48 +++++++++++++++++++--------------------
 1 file changed, 23 insertions(+), 25 deletions(-)

diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index d737300..0985b2b 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -647,31 +647,29 @@ static void xprt_rdma_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
 	if (xprt_connected(xprt))
 		idle_time = (long)(jiffies - xprt->last_used) / HZ;
 
-	seq_printf(seq,
-	  "\txprt:\trdma %u %lu %lu %lu %ld %lu %lu %lu %Lu %Lu "
-	  "%lu %lu %lu %Lu %Lu %Lu %Lu %lu %lu %lu\n",
-
-	   0,	/* need a local port? */
-	   xprt->stat.bind_count,
-	   xprt->stat.connect_count,
-	   xprt->stat.connect_time,
-	   idle_time,
-	   xprt->stat.sends,
-	   xprt->stat.recvs,
-	   xprt->stat.bad_xids,
-	   xprt->stat.req_u,
-	   xprt->stat.bklog_u,
-
-	   r_xprt->rx_stats.read_chunk_count,
-	   r_xprt->rx_stats.write_chunk_count,
-	   r_xprt->rx_stats.reply_chunk_count,
-	   r_xprt->rx_stats.total_rdma_request,
-	   r_xprt->rx_stats.total_rdma_reply,
-	   r_xprt->rx_stats.pullup_copy_count,
-	   r_xprt->rx_stats.fixup_copy_count,
-	   r_xprt->rx_stats.hardway_register_count,
-	   r_xprt->rx_stats.failed_marshal_count,
-	   r_xprt->rx_stats.bad_reply_count);
+	seq_puts(seq, "\txprt:\trdma ");
+	seq_printf(seq, "%u %lu %lu %lu %ld %lu %lu %lu %llu %llu ",
+		   0,	/* need a local port? */
+		   xprt->stat.bind_count,
+		   xprt->stat.connect_count,
+		   xprt->stat.connect_time,
+		   idle_time,
+		   xprt->stat.sends,
+		   xprt->stat.recvs,
+		   xprt->stat.bad_xids,
+		   xprt->stat.req_u,
+		   xprt->stat.bklog_u);
+	seq_printf(seq, "%lu %lu %lu %llu %llu %llu %llu %lu %lu %lu\n",
+		   r_xprt->rx_stats.read_chunk_count,
+		   r_xprt->rx_stats.write_chunk_count,
+		   r_xprt->rx_stats.reply_chunk_count,
+		   r_xprt->rx_stats.total_rdma_request,
+		   r_xprt->rx_stats.total_rdma_reply,
+		   r_xprt->rx_stats.pullup_copy_count,
+		   r_xprt->rx_stats.fixup_copy_count,
+		   r_xprt->rx_stats.hardway_register_count,
+		   r_xprt->rx_stats.failed_marshal_count,
+		   r_xprt->rx_stats.bad_reply_count);
 }
 
 static int

[PATCH v2 14/14] xprtrdma: Count RDMA_NOMSG type calls

[Chuck Lever]

RDMA_NOMSG type calls are less efficient than RDMA_MSG. Count NOMSG
calls so administrators can tell if they happen to be used more than
expected.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/rpc_rdma.c  |    1 +
 net/sunrpc/xprtrdma/transport.c |    5 +++--
 net/sunrpc/xprtrdma/xprt_rdma.h |    1 +
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 2721586..bc8bd65 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -489,6 +489,7 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	} else if (rqst->rq_snd_buf.flags & XDRBUF_WRITE) {
 		rtype = rpcrdma_readch;
 	} else {
+		r_xprt->rx_stats.nomsg_call_count++;
 		headerp->rm_type = htonl(RDMA_NOMSG);
 		rtype = rpcrdma_areadch;
 		rpclen = 0;
diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index 0985b2b..64443eb 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -659,7 +659,7 @@ static void xprt_rdma_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
 		   xprt->stat.bad_xids,
 		   xprt->stat.req_u,
 		   xprt->stat.bklog_u);
-	seq_printf(seq, "%lu %lu %lu %llu %llu %llu %llu %lu %lu %lu\n",
+	seq_printf(seq, "%lu %lu %lu %llu %llu %llu %llu %lu %lu %lu %lu\n",
 		   r_xprt->rx_stats.read_chunk_count,
 		   r_xprt->rx_stats.write_chunk_count,
 		   r_xprt->rx_stats.reply_chunk_count,
@@ -669,7 +669,8 @@ static void xprt_rdma_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
 		   r_xprt->rx_stats.fixup_copy_count,
 		   r_xprt->rx_stats.hardway_register_count,
 		   r_xprt->rx_stats.failed_marshal_count,
-		   r_xprt->rx_stats.bad_reply_count);
+		   r_xprt->rx_stats.bad_reply_count,
+		   r_xprt->rx_stats.nomsg_call_count);
 }
 
 static int
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 0b50103..886f8c8 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -340,6 +340,7 @@ struct rpcrdma_stats {
 	unsigned long		hardway_register_count;
 	unsigned long		failed_marshal_count;
 	unsigned long		bad_reply_count;
+	unsigned long		nomsg_call_count;
 };
 
 /*