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

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

On 02/17/2016 10:19 AM, Chuck Lever wrote:
> 
>> On Feb 17, 2016, at 10:16 AM, Anna Schumaker <Anna.Schumaker@netapp.com> wrote:
>>
>> 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?
> 
> Yes: xprt_complete_bc_request sets the private buffer length
> and sets RPC_BC_PA_IN_USE. So I want to group these two
> lines in their own paragraph just to "document" that they
> belong together and are not related to the lines above
> them.

Makes sense.  Thanks!

Anna

> 
> 
>>> +	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!
> 
> 
>> Thanks,
>> Anna
>>
>>> 	set_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state);
>>>
>>> 	buf = &rqst->rq_rcv_buf;
> 
> --
> Chuck Lever
> 
> 
> 
>