On Sep 22, 2014, at 11:39 AM, J. Bruce Fields <bfields@xxxxxxxxxxxx> 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?
Hey Bruce-
I don’t see the _TCP and _RDMA settings are related.
> --b.
>
>> +
>> #endif /* _LINUX_SUNRPC_XPRT_RDMA_H */
>>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
