Re: [RFC 10/11] nfsd41: Backchannel: Implement cb_recall over NFSv4.1

[Benny Halevy <bhalevy@panasas.com>]

On May. 20, 2009, 21:17 +0300, "Labiaga, Ricardo" <ricardo.labiaga@netapp.com> wrote:
> On 5/20/09 12:46 AM, "Benny Halevy" <bhalevy@panasas.com> wrote:
> 
>> On May. 20, 2009, 6:00 +0300, Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
>> wrote:
>>> Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
>>> [nfsd41: cb_recall callback]
>>> [Share v4.0 and v4.1 back channel xdr]
>>> Signed-off-by: Andy Adamson <andros@netapp.com>
>>> Signed-off-by: Ricardo Labiaga <ricardo.labiaga@netapp.com>
>>> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
>>> [Share v4.0 and v4.1 back channel xdr]
>>> Signed-off-by: Andy Adamson <andros@netapp.com>
>>> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
>>> [nfsd41: use nfsd4_cb_sequence for callback minorversion]
>>> [nfsd41: conditionally decode_sequence in nfs4_xdr_dec_cb_recall]
>>> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
>>> [nfsd41: Backchannel: Add sequence arguments to callback RPC arguments]
>>> Signed-off-by: Ricardo Labiaga <Ricardo.Labiaga@netapp.com>
>>> Signed-off-by: Benny Halevy <bhalevy@panasas.com>
>>> ---
>>>  fs/nfsd/nfs4callback.c |   40 ++++++++++++++++++++++++++++++++++++----
>>>  1 files changed, 36 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
>>> index 521d5f5..b25dcc2 100644
>>> --- a/fs/nfsd/nfs4callback.c
>>> +++ b/fs/nfsd/nfs4callback.c
>>> @@ -292,15 +292,19 @@ nfs4_xdr_enc_cb_null(struct rpc_rqst *req, __be32 *p)
>>>  }
>>>  
>>>  static int
>>> -nfs4_xdr_enc_cb_recall(struct rpc_rqst *req, __be32 *p, struct
>>> nfs4_delegation *args)
>>> +nfs4_xdr_enc_cb_recall(struct rpc_rqst *req, __be32 *p,
>>> +  struct nfs4_rpc_args *rpc_args)
>>>  {
>>> struct xdr_stream xdr;
>>> + struct nfs4_delegation *args = rpc_args->args_op;
>>> struct nfs4_cb_compound_hdr hdr = {
>>> .ident = args->dl_ident,
>>> +  .minorversion = rpc_args->args_seq.cbs_minorversion,
>>> };
>>>  
>>> xdr_init_encode(&xdr, &req->rq_snd_buf, p);
>>> encode_cb_compound_hdr(&xdr, &hdr);
>>> + encode_cb_sequence(&xdr, &rpc_args->args_seq, &hdr);
>>> encode_cb_recall(&xdr, args, &hdr);
>>> encode_cb_nops(&hdr);
>>> return 0;
>>> @@ -400,7 +404,8 @@ nfs4_xdr_dec_cb_null(struct rpc_rqst *req, __be32 *p)
>>>  }
>>>  
>>>  static int
>>> -nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp, __be32 *p)
>>> +nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp, __be32 *p,
>>> +  struct nfs4_rpc_res *rpc_res)
>>>  {
>>> struct xdr_stream xdr;
>>> struct nfs4_cb_compound_hdr hdr;
>>> @@ -410,6 +415,11 @@ nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp, __be32
>>> *p)
>>> status = decode_cb_compound_hdr(&xdr, &hdr);
>>> if (status)
>>> goto out;
>>> + if (rpc_res && rpc_res->res_seq) {
>> With this version rpc_res != NULL is guaranteed, isn't it?
>> Also, embedding res_seq in nfs4_rpc_res will obviate this condition further.
> 
> True, rpc_res will always be non-NULL but rpc_res->res_seq is still NULL if
> this is a v4.0 callback.
> 
>>> +  status = decode_cb_sequence(&xdr, rpc_res->res_seq, rqstp);
>>> +  if (status)
>>> +   goto out;
>>> + }
>>> status = decode_cb_op_hdr(&xdr, OP_CB_RECALL);
>>>  out:
>>> return status;
>>> @@ -687,6 +697,8 @@ static void nfsd4_cb_recall_done(struct rpc_task *task,
>>> void *calldata)
>>> struct nfs4_delegation *dp = calldata;
>>> struct nfs4_client *clp = dp->dl_client;
>>>  
>>> + nfsd4_cb_done(task, calldata);
>>> +
>>> switch (task->tk_status) {
>>> case -EIO:
>>> /* Network partition? */
>>> @@ -699,16 +711,20 @@ static void nfsd4_cb_recall_done(struct rpc_task *task,
>>> void *calldata)
>>> break;
>>> default:
>>> /* success, or error we can't handle */
>>> -  return;
>>> +  goto done;
>>> }
>>> if (dp->dl_retries--) {
>>> rpc_delay(task, 2*HZ);
>>> task->tk_status = 0;
>>> rpc_restart_call(task);
>>> +  return;
>>> } else {
>>> atomic_set(&clp->cl_cb_conn.cb_set, 0);
>>> warn_no_callback_path(clp, task->tk_status);
>>> }
>>> +done:
>>> + kfree(task->tk_msg.rpc_argp);
>>> + kfree(task->tk_msg.rpc_resp);
>>>  }
>>>  
>>>  static void nfsd4_cb_recall_release(void *calldata)
>>> @@ -734,16 +750,32 @@ nfsd4_cb_recall(struct nfs4_delegation *dp)
>>>  {
>>> struct nfs4_client *clp = dp->dl_client;
>>> struct rpc_clnt *clnt = clp->cl_cb_conn.cb_client;
>>> + struct nfs4_rpc_args *args;
>>> + struct nfs4_rpc_res *res;
>>> struct rpc_message msg = {
>>> .rpc_proc = &nfs4_cb_procedures[NFSPROC4_CLNT_CB_RECALL],
>>> -  .rpc_argp = dp,
>>> .rpc_cred = clp->cl_cb_conn.cb_cred
>>> };
>>> int status;
>>>  
>>> + args = kzalloc(sizeof(*args), GFP_KERNEL);
>>> + if (!args) {
>>> +  status = -ENOMEM;
>>> +  goto out;
>>> + }
>>> + res = kzalloc(sizeof(*res), GFP_KERNEL);
>>> + if (!res) {
>>> +  kfree(args);
>>> +  status = -ENOMEM;
>>> +  goto out;
>>> + }
>> Hmm, why not allocate the two in one piece and possibly having a kmem_cache
>> for them?
> 
> They're two different types of structures.  You mean encapsulate them in a
> super structure and then have the pointers to respective members?  I'm not
> following.

Exactly.

I meant something like this:

struct nfs4_rpc_alloc {
	struct nfs4_rpc_args args;
	struct nfs4_rpc_res res;
};

However, as you pointed elsewhere, struct nfs4_rpc_res currently
contains only a pointer to struct nfsd4_cb_sequence which is embedded
in the nfs4_rpc_args so we can just get rid of struct nfs4_rpc_res
altogether for now, until we have a better use for it, and set
	task->tk_msg.rpc_resp = &args->args_seq;
directly in nfsd41_cb_setup_sequence.
(or even up in nfsd4_cb_recall and friends so it's always set,
for all minorversions, as decode_cb_sequence is a noop for
res->cbs_minorversion==0)

Benny

> 
> - ricardo
> 
>> Benny
>>
>>> + args->args_op = dp;
>>> + msg.rpc_argp = args;
>>> + msg.rpc_resp = res;
>>> dp->dl_retries = 1;
>>> status = rpc_call_async(clnt, &msg, RPC_TASK_SOFT,
>>> &nfsd4_cb_recall_ops, dp);
>>> +out:
>>> if (status) {
>>> put_nfs4_client(clp);
>>> nfs4_put_delegation(dp);
>