On 9/22/2014 1:55 PM, J. Bruce Fields wrote:
On Mon, Sep 22, 2014 at 01:42:07PM -0500, Steve Wise wrote:
On 9/22/2014 1:39 PM, J. Bruce Fields wrote:
On Mon, Sep 22, 2014 at 01:36:53PM -0500, Steve Wise wrote:
Svcrdma currently advertises 1MB, which is too large. The correct value
is the max scatter-gather allowed in an NFSRDMA IO chunk * the host page
size. This bug is usually benign because the Linux X64 NFSRDMA client
correctly limits the payload size to the correct value (64*4096 = 256KB).
But if the Linux client is PPC64 with a 64KB page size, then the client
will indeed use a payload size that will overflow the server.
Signed-off-by: Steve Wise <swise@xxxxxxxxxxxxxxxxxxxxx>
---
net/sunrpc/xprtrdma/svc_rdma_transport.c | 2 +-
net/sunrpc/xprtrdma/xprt_rdma.h | 2 ++
2 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index 374feb4..4e61880 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -91,7 +91,7 @@ struct svc_xprt_class svc_rdma_class = {
.xcl_name = "rdma",
.xcl_owner = THIS_MODULE,
.xcl_ops = &svc_rdma_ops,
- .xcl_max_payload = RPCSVC_MAXPAYLOAD_TCP,
+ .xcl_max_payload = RPCSVC_MAXPAYLOAD_RDMA,
.xcl_ident = XPRT_TRANSPORT_RDMA,
};
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index c419498..467a77c 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -392,4 +392,6 @@ extern struct kmem_cache *svc_rdma_ctxt_cachep;
/* Workqueue created in svc_rdma.c */
extern struct workqueue_struct *svc_rdma_wq;
+#define RPCSVC_MAXPAYLOAD_RDMA (RPCRDMA_MAX_DATA_SEGS << PAGE_SHIFT)
Do you want to define this as the minimum of this and
RPCSVC_MAXPAYLOAD_TCP, in case RPCRDMA_MAX_DATA_SEGS gets increased some
day?
Why would it need to be limited by MAXPAYLOAD_TCP?
Because you're also limited by the size of the rq_pages array, which is
determined by RPCSVC_MAXPAGES, calculated from RPCSVC_MAXPAYLOAD.
(Actually you probably want RPCSVC_MAXPAYLOAD, not MAXPAYLOAD_TCP.)
I see. I agree.
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