Re: [PATCH] xprtrdma: rpcrdma_bc_receive_call() should init rq_private_buf.len

[Anna Schumaker <Anna.Schumaker@netapp.com>]

Hi Chuck,

On 02/15/2016 10:23 AM, Chuck Lever wrote:
> Some NFSv4.1 OPEN requests were hanging waiting for the NFS server
> to finish recalling delegations. Turns out that each NFSv4.1 CB
> request on RDMA gets a GARBAGE_ARGS reply from the Linux client.
> 
> Commit 756b9b37cfb2e3dc added a line in bc_svc_process that
> overwrites the incoming rq_rcv_buf's length with the value in
> rq_private_buf.len. But rpcrdma_bc_receive_call() does not invoke
> xprt_complete_bc_request(), thus rq_private_buf.len is not
> initialized. svc_process_common() is invoked with a zero-length
> RPC message, and fails.
> 
> Fixes: 756b9b37cfb2e3dc ('SUNRPC: Fix callback channel')
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
> Hi Anna-
> 
> Commit 756b9b37cfb2e3dc in v4.5-rc1 introduced a behavior
> regression for NFSv4.1-over-RDMA. Would it be possible to merge
> this bug fix into 4.5-rc ?
> 
> 
>  net/sunrpc/xprtrdma/backchannel.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/net/sunrpc/xprtrdma/backchannel.c b/net/sunrpc/xprtrdma/backchannel.c
> index cc1251d..2dcd764 100644
> --- a/net/sunrpc/xprtrdma/backchannel.c
> +++ b/net/sunrpc/xprtrdma/backchannel.c
> @@ -341,6 +341,8 @@ void rpcrdma_bc_receive_call(struct rpcrdma_xprt *r_xprt,
>  	rqst->rq_reply_bytes_recvd = 0;
>  	rqst->rq_bytes_sent = 0;
>  	rqst->rq_xid = headerp->rm_xid;
> +

nit: Any reason for the extra newline?

> +	rqst->rq_private_buf.len = size;

This patch looks okay to me, and I'll make sure it's included in the next rc pull request Trond sends.

Thanks,
Anna

>  	set_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state);
>  
>  	buf = &rqst->rq_rcv_buf;
>