> On Dec 18, 2018, at 2:35 PM, Anna Schumaker <schumaker.anna@xxxxxxxxx> wrote:
>
> Hi Chuck,
>
> On Mon, 2018-12-17 at 11:39 -0500, Chuck Lever wrote:
>> With certain combinations of krb5i/p, MR size, and r/wsize, I/O can
>> fail with EMSGSIZE. This is because the calculated value of
>> ri_max_segs (the max number of MRs per RPC) exceeded
>> RPCRDMA_MAX_HDR_SEGS, which caused Read or Write list encoding to
>> walk off the end of the transport header.
>>
>> Once that was addressed, the ro_maxpages result has to be corrected
>> to account for the number of MRs needed for Reply chunks, which is
>> 2 MRs smaller than a normal Read or Write chunk.
>>
>> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
>> ---
>> net/sunrpc/xprtrdma/fmr_ops.c | 7 +++++--
>> net/sunrpc/xprtrdma/frwr_ops.c | 7 +++++--
>> net/sunrpc/xprtrdma/transport.c | 6 ++++--
>> 3 files changed, 14 insertions(+), 6 deletions(-)
>>
>> diff --git a/net/sunrpc/xprtrdma/fmr_ops.c b/net/sunrpc/xprtrdma/fmr_ops.c
>> index 7f5632c..78a0224 100644
>> --- a/net/sunrpc/xprtrdma/fmr_ops.c
>> +++ b/net/sunrpc/xprtrdma/fmr_ops.c
>> @@ -176,7 +176,10 @@ enum {
>>
>> ia->ri_max_segs = max_t(unsigned int, 1, RPCRDMA_MAX_DATA_SEGS /
>> RPCRDMA_MAX_FMR_SGES);
>> - ia->ri_max_segs += 2; /* segments for head and tail buffers */
>> + /* Reply chunks require segments for head and tail buffers */
>> + ia->ri_max_segs += 2;
>> + if (ia->ri_max_segs > RPCRDMA_MAX_HDR_SEGS)
>> + ia->ri_max_segs = RPCRDMA_MAX_HDR_SEGS;
>> return 0;
>> }
>>
>> @@ -186,7 +189,7 @@ enum {
>> fmr_op_maxpages(struct rpcrdma_xprt *r_xprt)
>> {
>> return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
>> - RPCRDMA_MAX_HDR_SEGS * RPCRDMA_MAX_FMR_SGES);
>> + (ia->ri_max_segs - 2) * RPCRDMA_MAX_FMR_SGES);
>
> ia isn't defined in this function. Should that be r_xprt->rx_ia.ri_max_segs
> instead?
Yeah. I compile-tested the tip of the branch, and so missed
this.
I'm going to have to send you a v5, so I'll fix this up in
the next post of this series.
> Thanks,
> Anna
>
>> }
>>
>> /* Use the ib_map_phys_fmr() verb to register a memory region
>> diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
>> index 27222c0..f587e44 100644
>> --- a/net/sunrpc/xprtrdma/frwr_ops.c
>> +++ b/net/sunrpc/xprtrdma/frwr_ops.c
>> @@ -244,7 +244,10 @@
>>
>> ia->ri_max_segs = max_t(unsigned int, 1, RPCRDMA_MAX_DATA_SEGS /
>> ia->ri_max_frwr_depth);
>> - ia->ri_max_segs += 2; /* segments for head and tail buffers */
>> + /* Reply chunks require segments for head and tail buffers */
>> + ia->ri_max_segs += 2;
>> + if (ia->ri_max_segs > RPCRDMA_MAX_HDR_SEGS)
>> + ia->ri_max_segs = RPCRDMA_MAX_HDR_SEGS;
>> return 0;
>> }
>>
>> @@ -257,7 +260,7 @@
>> struct rpcrdma_ia *ia = &r_xprt->rx_ia;
>>
>> return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
>> - RPCRDMA_MAX_HDR_SEGS * ia->ri_max_frwr_depth);
>> + (ia->ri_max_segs - 2) * ia->ri_max_frwr_depth);
>> }
>>
>> static void
>> diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
>> index a16296b..fbb14bf 100644
>> --- a/net/sunrpc/xprtrdma/transport.c
>> +++ b/net/sunrpc/xprtrdma/transport.c
>> @@ -704,8 +704,10 @@
>> * %-ENOTCONN if the caller should reconnect and call again
>> * %-EAGAIN if the caller should call again
>> * %-ENOBUFS if the caller should call again after a delay
>> - * %-EIO if a permanent error occurred and the request was not
>> - * sent. Do not try to send this message again.
>> + * %-EMSGSIZE if encoding ran out of buffer space. The request
>> + * was not sent. Do not try to send this message again.
>> + * %-EIO if an I/O error occurred. The request was not sent.
>> + * Do not try to send this message again.
>> */
>> static int
>> xprt_rdma_send_request(struct rpc_rqst *rqst)
--
Chuck Lever
