Re: [PATCH RFC 14/24] nfsd: wire up GET_DIR_DELEGATION handling

[Chuck Lever]

On Fri, Mar 15, 2024 at 12:53:05PM -0400, Jeff Layton wrote:
> Add a new routine for acquiring a read delegation on a directory. Since
> the same CB_RECALL/DELEGRETURN infrastrure is used for regular and
> directory delegations, we can just use a normal nfs4_delegation to
> represent it.
> 
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
>  fs/nfsd/nfs4proc.c  | 23 ++++++++++++++++--
>  fs/nfsd/nfs4state.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
>  fs/nfsd/state.h     |  5 ++++
>  3 files changed, 94 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 7973fe17bf3c..1a2c90f4ea53 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -2179,9 +2179,28 @@ nfsd4_get_dir_delegation(struct svc_rqst *rqstp,
>  			 union nfsd4_op_u *u)
>  {
>  	struct nfsd4_get_dir_delegation *gdd = &u->get_dir_delegation;
> +	struct nfs4_delegation *dd;
> +	struct nfsd_file *nf;
> +	__be32 status;
> +
> +	status = nfsd_file_acquire_dir(rqstp, &cstate->current_fh, &nf);
> +	if (status != nfs_ok)
> +		return status;
> +
> +	dd = nfsd_get_dir_deleg(cstate, gdd, nf);
> +	if (IS_ERR(dd)) {
> +		int err = PTR_ERR(dd);
> +
> +		if (err != -EAGAIN)
> +			return nfserrno(err);
> +		gdd->nf_status = GDD4_UNAVAIL;
> +		return nfs_ok;
> +	}
>  
> -	/* FIXME: actually return a delegation */
> -	gdd->nf_status = GDD4_UNAVAIL;
> +	gdd->nf_status = GDD4_OK;
> +	memcpy(&gdd->stateid, &dd->dl_stid.sc_stateid, sizeof(gdd->stateid));
> +	memset(&gdd->cookieverf, '\0', sizeof(gdd->cookieverf));
> +	nfs4_put_stid(&dd->dl_stid);
>  	return nfs_ok;
>  }
>  
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 778c1c6e3b54..36574aedc211 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -8874,7 +8874,7 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
>  			}
>  break_lease:
>  			nfsd_stats_wdeleg_getattr_inc(nn);
> -			dp = fl->fl_owner;
> +			dp = fl->c.flc_owner;
>  			ncf = &dp->dl_cb_fattr;
>  			nfs4_cb_getattr(&dp->dl_cb_fattr);
>  			spin_unlock(&ctx->flc_lock);
> @@ -8912,3 +8912,70 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct inode *inode,
>  	spin_unlock(&ctx->flc_lock);
>  	return 0;
>  }
> +

I'll admit to not having examined the below function closely, but
since it is not a static function, can you add a kdoc comment and
a few salient points like, if there is something NFSD doesn't
implement (yet), or short cuts that would be good for readers to
know about?


> +struct nfs4_delegation *
> +nfsd_get_dir_deleg(struct nfsd4_compound_state *cstate,
> +		   struct nfsd4_get_dir_delegation *gdd,
> +		   struct nfsd_file *nf)
> +{
> +	struct nfs4_client *clp = cstate->clp;
> +	struct nfs4_delegation *dp;
> +	struct file_lease *fl;
> +	struct nfs4_file *fp;
> +	int status = 0;
> +
> +	fp = nfsd4_alloc_file();
> +	if (!fp)
> +		return ERR_PTR(-ENOMEM);
> +
> +	nfsd4_file_init(&cstate->current_fh, fp);
> +	fp->fi_deleg_file = nf;
> +	fp->fi_delegees = 1;
> +
> +	spin_lock(&state_lock);
> +	spin_lock(&fp->fi_lock);
> +	if (nfs4_delegation_exists(clp, fp))
> +		status = -EAGAIN;
> +	spin_unlock(&fp->fi_lock);
> +	spin_unlock(&state_lock);
> +
> +	if (status)
> +		goto out_delegees;
> +
> +	status = -ENOMEM;
> +	dp = alloc_init_deleg(clp, fp, NULL, NFS4_OPEN_DELEGATE_READ);
> +	if (!dp)
> +		goto out_delegees;
> +
> +	fl = nfs4_alloc_init_lease(dp, NFS4_OPEN_DELEGATE_READ);
> +	if (!fl)
> +		goto out_put_stid;
> +
> +	status = kernel_setlease(nf->nf_file,
> +				 fl->c.flc_type, &fl, NULL);
> +	if (fl)
> +		locks_free_lease(fl);
> +	if (status)
> +		goto out_put_stid;
> +
> +	spin_lock(&state_lock);
> +	spin_lock(&clp->cl_lock);
> +	spin_lock(&fp->fi_lock);
> +	status = hash_delegation_locked(dp, fp);
> +	spin_unlock(&fp->fi_lock);
> +	spin_unlock(&clp->cl_lock);
> +	spin_unlock(&state_lock);
> +
> +	if (status)
> +		goto out_unlock;
> +
> +	return dp;
> +out_unlock:
> +	kernel_setlease(fp->fi_deleg_file->nf_file, F_UNLCK, NULL, (void **)&dp);
> +out_put_stid:
> +	nfs4_put_stid(&dp->dl_stid);
> +out_delegees:
> +	put_deleg_file(fp);
> +	return ERR_PTR(status);
> +}
> +
> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> index 01c6f3445646..20551483cc7b 100644
> --- a/fs/nfsd/state.h
> +++ b/fs/nfsd/state.h
> @@ -782,4 +782,9 @@ static inline bool try_to_expire_client(struct nfs4_client *clp)
>  
>  extern __be32 nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp,
>  		struct inode *inode, bool *file_modified, u64 *size);
> +
> +struct nfsd4_get_dir_delegation;
> +struct nfs4_delegation *nfsd_get_dir_deleg(struct nfsd4_compound_state *cstate,
> +						struct nfsd4_get_dir_delegation *gdd,
> +						struct nfsd_file *nf);
>  #endif   /* NFSD4_STATE_H */
> 
> -- 
> 2.44.0
> 

-- 
Chuck Lever