Re: [pnfs] [RFC 44/51] nfsd41: slab cache for current session

[Benny Halevy <bhalevy@panasas.com>]

On Nov. 10, 2008, 22:55 +0200, Benny Halevy <bhalevy@panasas.com> wrote:
> From: Andy Adamson <andros@netapp.com>
> 
> Use a separate slab cache for the current session so that an NFSv4.1 server
> responding to NFSv4.0 requests uses only the compound state slab.
> 
> Signed-off-by: Andy Adamson<andros@netapp.com>
> Signed-off-by: Benny Halevy <bhalevy@panasas.com>

review 11-12: just embed struct current_session in
nfsd4_compound_state and nfsd4_coumpoundres

> ---
>  fs/nfsd/nfs4proc.c        |   36 +++++++++++++++++-------------------
>  fs/nfsd/nfs4state.c       |   28 ++++++++++++++++++++++++++++
>  include/linux/nfsd/xdr4.h |    2 ++
>  3 files changed, 47 insertions(+), 19 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index deefba1..eaebe5b 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -942,9 +942,6 @@ nfsd4_proc_compound(struct svc_rqst *rqstp,
>  	struct nfsd4_compound_state *cstate = NULL;
>  	int		slack_bytes;
>  	__be32		status = nfs_ok;
> -#if defined(CONFIG_NFSD_V4_1)
> -	struct current_session *current_ses = NULL;
> -#endif /* CONFIG_NFSD_V4_1 */
>  
>  	resp->xbuf = &rqstp->rq_res;
>  	resp->p = rqstp->rq_res.head[0].iov_base + rqstp->rq_res.head[0].iov_len;
> @@ -970,6 +967,19 @@ nfsd4_proc_compound(struct svc_rqst *rqstp,
>  	if (cstate == NULL)
>  		goto out;
>  
> +#ifdef CONFIG_NFSD_V4_1
> +	/* cstate->current_ses could be set revisiting a deferal */
> +	if (args->minorversion == 1 && !cstate->current_ses) {
> +		cstate->current_ses = nfsd41_current_session_alloc();
> +		if (cstate->current_ses == NULL) {
> +			/* still nfserr_resource */
> +			nfsd4_cstate_free(cstate, rqstp->rq_deferred);
> +			goto out;
> +		}
> +		cstate->current_ses->cs_slot = NULL;
> +	}
> +#endif /* CONFIG_NFSD_V4_1 */
> +
>  	if (rqstp->rq_deferred && rqstp->rq_deferred->defer_data) {
>  		dprintk("%s Resuming deferred processing\n", __func__);
>  		resp->opcnt = cstate->last_op_cnt;
> @@ -985,17 +995,6 @@ nfsd4_proc_compound(struct svc_rqst *rqstp,
>  	rqstp->rq_defer_data = cstate;
>  	rqstp->rq_save_state = nfsd4_save_deferred_state;
>  
> -#if defined(CONFIG_NFSD_V4_1)
> -	if (args->minorversion == 1) {
> -		/* FIXME: use kmem_cache */
> -		current_ses = kzalloc(sizeof(*current_ses), GFP_KERNEL);
> -		if (current_ses == NULL)
> -			goto out_free;
> -	}
> -	/* DM: current_ses must be NULL for minorversion 0 */
> -	cstate->current_ses = current_ses;
> -#endif /* CONFIG_NFSD_V4_1 */
> -
>  	status = nfs_ok;
>  	while (!status && resp->opcnt < args->opcnt) {
>  		cstate->last_op_p = resp->p;
> @@ -1081,12 +1080,11 @@ encode_op:
>  		return status;
>  	}
>  
> -out_free:
>  #if defined(CONFIG_NFSD_V4_1)
> -	if (current_ses) {
> -		struct nfs41_slot *cs_slot = current_ses->cs_slot;
> +	if (cstate->current_ses) {
> +		struct nfs41_slot *cs_slot = cstate->current_ses->cs_slot;
>  		if (cs_slot) {
> -			if (op && op->status != nfserr_dropit) {
> +			if (status != nfserr_dropit) {
>  				dprintk("%s: SET SLOT STATE TO AVAILABLE\n",
>  					__func__);
>  				nfs41_set_slot_state(cs_slot,
> @@ -1094,7 +1092,7 @@ out_free:
>  			}
>  			nfs41_put_session(cs_slot->sl_session);
>  		}
> -		kfree(current_ses);
> +		nfsd41_current_session_free(cstate->current_ses);
>  	}
>  #endif /* CONFIG_NFSD_V4_1 */
>  	nfsd4_cstate_free(cstate, rqstp->rq_deferred);
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 8fd7704..ba6ab19 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -102,6 +102,9 @@ static struct kmem_cache *file_slab = NULL;
>  static struct kmem_cache *stateid_slab = NULL;
>  static struct kmem_cache *deleg_slab = NULL;
>  static struct kmem_cache *cstate_slab;
> +#ifdef CONFIG_NFSD_V4_1
> +static struct kmem_cache *current_session_slab;
> +#endif /* CONFIG_NFSD_V4_1 */
>  
>  #define BUG_ON_UNLOCKED_STATE() BUG_ON(mutex_trylock(&client_mutex))
>  
> @@ -479,6 +482,19 @@ free_session(struct kref *kref)
>  	kfree(ses->se_slots);
>  	kfree(ses);
>  }
> +
> +void
> +nfsd41_current_session_free(struct current_session *cses)
> +{
> +	kmem_cache_free(current_session_slab, cses);
> +}
> +
> +struct current_session *
> +nfsd41_current_session_alloc(void)
> +{
> +	return kmem_cache_alloc(current_session_slab, GFP_KERNEL);
> +}
> +
>  #endif /* CONFIG_NFSD_V4_1 */
>  
>  void
> @@ -511,6 +527,9 @@ nfsd4_cstate_alloc(struct svc_rqst *rqstp)
>  	fh_init(&cstate->current_fh, NFS4_FHSIZE);
>  	fh_init(&cstate->save_fh, NFS4_FHSIZE);
>  	cstate->replay_owner = NULL;
> +#ifdef CONFIG_NFSD_V4_1
> +	cstate->current_ses = NULL;
> +#endif /* CONFIG_NFSD_V4_1 */
>  out:
>  	return cstate;
>  }
> @@ -1565,6 +1584,9 @@ nfsd4_free_slabs(void)
>  	nfsd4_free_slab(&stateid_slab);
>  	nfsd4_free_slab(&deleg_slab);
>  	nfsd4_free_slab(&cstate_slab);
> +#ifdef CONFIG_NFSD_V4_1
> +	nfsd4_free_slab(&current_session_slab);
> +#endif /* CONFIG_NFSD_V4_1 */
>  }
>  
>  static int
> @@ -1590,6 +1612,12 @@ nfsd4_init_slabs(void)
>  			sizeof(struct nfsd4_compound_state), 0, 0, NULL);
>  	if (cstate_slab == NULL)
>  		goto out_nomem;
> +#ifdef CONFIG_NFSD_V4_1
> +	current_session_slab = kmem_cache_create("nfsd4_current_sessions",
> +			sizeof(struct current_session), 0, 0, NULL);
> +	if (current_session_slab == NULL)
> +		goto out_nomem;
> +#endif /* CONFIG_NFSD_V4_1 */
>  	return 0;
>  out_nomem:
>  	nfsd4_free_slabs();
> diff --git a/include/linux/nfsd/xdr4.h b/include/linux/nfsd/xdr4.h
> index a0b4f00..fc42fba 100644
> --- a/include/linux/nfsd/xdr4.h
> +++ b/include/linux/nfsd/xdr4.h
> @@ -532,6 +532,8 @@ extern __be32 nfsd4_setclientid_confirm(struct svc_rqst *rqstp,
>  		struct nfsd4_compound_state *,
>  		struct nfsd4_setclientid_confirm *setclientid_confirm);
>  #if defined(CONFIG_NFSD_V4_1)
> +extern void nfsd41_current_session_free(struct current_session *cses);
> +extern struct current_session *nfsd41_current_session_alloc(void);
>  extern __be32 nfsd4_exchange_id(struct svc_rqst *rqstp,
>  		struct nfsd4_compound_state *,
>  		struct nfsd4_exchange_id *);