Re: [PATCH v2 11/11] nfsd: wire up GET_DIR_DELEGATION handling

On Sat, 2025-10-18 at 15:46 -0400, Chuck Lever wrote:
> On 10/17/25 7:32 AM, Jeff Layton wrote:
> > Add a new routine for acquiring a read delegation on a directory. These
> > are recallable-only delegations with no support for CB_NOTIFY. That will
> > be added in a later phase.
> > 
> > Since the same CB_RECALL/DELEGRETURN infrastrure is used for regular and
> > directory delegations, a normal nfs4_delegation is used to represent a
> > directory delegation.
> 
> s/infrastrure/infrastructure/
> 
> 
> > Signed-off-by: Jeff Layton <[email protected]>
> > ---
> >  fs/nfsd/nfs4proc.c  |  21 ++++++++++-
> >  fs/nfsd/nfs4state.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  fs/nfsd/state.h     |   5 +++
> >  3 files changed, 125 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> > index 7f7e6bb23a90d9a1cafd154c0f09e236df75b083..527f8dc52159803770964700170473509ec328ed 100644
> > --- a/fs/nfsd/nfs4proc.c
> > +++ b/fs/nfsd/nfs4proc.c
> > @@ -2342,6 +2342,13 @@ 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;
> >  
> >  	/*
> >  	 * RFC 8881, section 18.39.3 says:
> > @@ -2355,7 +2362,19 @@ nfsd4_get_dir_delegation(struct svc_rqst *rqstp,
> >  	 * return NFS4_OK with a non-fatal status of GDD4_UNAVAIL in this
> >  	 * situation.
> >  	 */
> > -	gdd->gddrnf_status = GDD4_UNAVAIL;
> > +	dd = nfsd_get_dir_deleg(cstate, gdd, nf);
> > +	if (IS_ERR(dd)) {
> > +		int err = PTR_ERR(dd);
> > +
> > +		if (err != -EAGAIN)
> > +			return nfserrno(err);
> > +		gdd->gddrnf_status = GDD4_UNAVAIL;
> > +		return nfs_ok;
> > +	}
> 
> These error flows might leak the nf acquired just above.
> 

Good catch. I'll fix that.

> 
> > +
> > +	gdd->gddrnf_status = GDD4_OK;
> > +	memcpy(&gdd->gddr_stateid, &dd->dl_stid.sc_stateid, sizeof(gdd->gddr_stateid));
> > +	nfs4_put_stid(&dd->dl_stid);
> >  	return nfs_ok;
> >  }
> >  
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index b06591f154aa372db710e071c69260f4639956d7..a63e8c885291fc377163f3255f26f5f693704437 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -9359,3 +9359,103 @@ nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp, struct dentry *dentry,
> >  	nfs4_put_stid(&dp->dl_stid);
> >  	return status;
> >  }
> > +
> > +/**
> > + * nfsd_get_dir_deleg - attempt to get a directory delegation
> > + * @cstate: compound state
> > + * @gdd: GET_DIR_DELEGATION arg/resp structure
> > + * @nf: nfsd_file opened on the directory
> > + *
> > + * Given a GET_DIR_DELEGATION request @gdd, attempt to acquire a delegation
> > + * on the directory to which @nf refers. Note that this does not set up any
> > + * sort of async notifications for the delegation.
> > + */
> > +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, *rfp;
> > +	int status = 0;
> > +
> > +	fp = nfsd4_alloc_file();
> > +	if (!fp)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	nfsd4_file_init(&cstate->current_fh, fp);
> > +
> > +	rfp = nfsd4_file_hash_insert(fp, &cstate->current_fh);
> > +	if (unlikely(!rfp)) {
> > +		put_nfs4_file(fp);
> > +		return ERR_PTR(-ENOMEM);
> > +	}
> > +
> > +	if (rfp != fp) {
> > +		put_nfs4_file(fp);
> > +		fp = rfp;
> > +	}
> > +
> > +	/* if this client already has one, return that it's unavailable */
> > +	spin_lock(&state_lock);
> > +	spin_lock(&fp->fi_lock);
> > +	/* existing delegation? */
> > +	if (nfs4_delegation_exists(clp, fp)) {
> > +		status = -EAGAIN;
> > +	} else if (!fp->fi_deleg_file) {
> > +		fp->fi_deleg_file = nf;
> > +		fp->fi_delegees = 1;
> > +	} else {
> > +		++fp->fi_delegees;
> 
> The new nf is unused in this arm. Does it need to be released?
> 

Yes. Good catch!

> 
> > +	}
> > +	spin_unlock(&fp->fi_lock);
> > +	spin_unlock(&state_lock);
> > +
> > +	if (status) {
> > +		put_nfs4_file(fp);
> > +		return ERR_PTR(status);
> > +	}
> > +
> > +	/* Try to set up the lease */
> > +	status = -ENOMEM;
> > +	dp = alloc_init_deleg(clp, fp, NULL, NFS4_OPEN_DELEGATE_READ);
> > +	if (!dp)
> > +		goto out_delegees;
> > +
> > +	fl = nfs4_alloc_init_lease(dp);
> > +	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;
> > +
> > +	/*
> > +	 * Now, try to hash it. This can fail if we race another nfsd task
> > +	 * trying to set a delegation on the same file. If that happens,
> > +	 * then just say UNAVAIL.
> > +	 */
> > +	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)
> > +		return dp;
> > +
> > +	/* Something failed. Drop the lease and clean up the stid */
> > +	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 1e736f4024263ffa9c93bcc9ec48f44566a8cc77..b052c1effdc5356487c610db9728df8ecfe851d4 100644
> > --- a/fs/nfsd/state.h
> > +++ b/fs/nfsd/state.h
> > @@ -867,4 +867,9 @@ static inline bool try_to_expire_client(struct nfs4_client *clp)
> >  
> >  extern __be32 nfsd4_deleg_getattr_conflict(struct svc_rqst *rqstp,
> >  		struct dentry *dentry, struct nfs4_delegation **pdp);
> > +
> > +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 */
> > 
> 

-- 
Jeff Layton <[email protected]>