[PATCH v4 03/21] xprtrdma: Limit data payload size for ALLPHYSICAL

Chuck Lever
2014-07-22T14:51:24Z

When the client uses physical memory registration, each page in the
payload gets its own array entry in the RPC/RDMA header's chunk list.

Therefore, don't advertise a maximum payload size that would require
more array entries than can fit in the RPC buffer where RPC/RDMA
headers are built.

BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=248
Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Tested-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
Tested-by: Shirley Ma <shirley.ma-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Tested-by: Devesh Sharma <devesh.sharma-laKkSmNT4hbQT0dZR+AlfA@public.gmane.org>
---
net/sunrpc/xprtrdma/transport.c | 4 +++-
net/sunrpc/xprtrdma/verbs.c | 41 +++++++++++++++++++++++++++++++++++++++
net/sunrpc/xprtrdma/xprt_rdma.h | 1 +
3 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index 66f91f0..4185102 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -296,7 +296,6 @@ xprt_setup_rdma(struct xprt_create *args)

xprt->resvport = 0; /* privileged port not needed */
xprt->tsh_size = 0; /* RPC-RDMA handles framing */
- xprt->max_payload = RPCRDMA_MAX_DATA_SEGS * PAGE_SIZE;
xprt->ops = &xprt_rdma_procs;

/*
@@ -382,6 +381,9 @@ xprt_setup_rdma(struct xprt_create *args)
new_ep->rep_xprt = xprt;

xprt_rdma_format_addresses(xprt);
+ xprt->max_payload = rpcrdma_max_payload(new_xprt);
+ dprintk("RPC: %s: transport data payload maximum: %zu bytes\n",
+ __func__, xprt->max_payload);

if (!try_module_get(THIS_MODULE))
goto out4;
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index cab742d..0d5187d 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -1822,3 +1822,44 @@ rpcrdma_ep_post_recv(struct rpcrdma_ia *ia,
rc);
return rc;
}
+
+/* Physical mapping means one Read/Write list entry per-page.
+ * All list entries must fit within an inline buffer
+ *
+ * NB: The server must return a Write list for NFS READ,
+ * which has the same constraint. Factor in the inline
+ * rsize as well.
+ */
+static size_t
+rpcrdma_physical_max_payload(struct rpcrdma_xprt *r_xprt)
+{
+ struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
+ unsigned int inline_size, pages;
+
+ inline_size = min_t(unsigned int,
+ cdata->inline_wsize, cdata->inline_rsize);
+ inline_size -= RPCRDMA_HDRLEN_MIN;
+ pages = inline_size / sizeof(struct rpcrdma_segment);
+ return pages << PAGE_SHIFT;
+}
+
+static size_t
+rpcrdma_mr_max_payload(struct rpcrdma_xprt *r_xprt)
+{
+ return RPCRDMA_MAX_DATA_SEGS << PAGE_SHIFT;
+}
+
+size_t
+rpcrdma_max_payload(struct rpcrdma_xprt *r_xprt)
+{
+ size_t result;
+
+ switch (r_xprt->rx_ia.ri_memreg_strategy) {
+ case RPCRDMA_ALLPHYSICAL:
+ result = rpcrdma_physical_max_payload(r_xprt);
+ break;
+ default:
+ result = rpcrdma_mr_max_payload(r_xprt);
+ }
+ return result;
+}
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 97ca516..f3d86b2 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -348,6 +348,7 @@ void rpcrdma_reply_handler(struct rpcrdma_rep *);
* RPC/RDMA protocol calls - xprtrdma/rpc_rdma.c
*/
int rpcrdma_marshal_req(struct rpc_rqst *);
+size_t rpcrdma_max_payload(struct rpcrdma_xprt *);

/* Temporary NFS request map cache. Created in svc_rdma.c */
extern struct kmem_cache *svc_rdma_map_cachep;

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