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?
--b.
> +
> #endif /* _LINUX_SUNRPC_XPRT_RDMA_H */
>
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