[PATCH v6 16/17] nfsd: wire up GET_DIR_DELEGATION handling

Jeff Layton
2025-11-11T14:13:59Z

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 infrastructure is used for regular
and directory delegations, a normal nfs4_delegation is used to represent
a directory delegation.

Reviewed-by: NeilBrown <neil@brown.name>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
fs/nfsd/nfs4proc.c | 22 +++++++++++-
fs/nfsd/nfs4state.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/nfsd/state.h | 5 +++
3 files changed, 126 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index e466cf52d7d7e1a78c3a469613a85ab3546d6d17..517968dddf4a33651313658d300f9f929f83c5af 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -2341,6 +2341,13 @@ 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:
@@ -2354,7 +2361,20 @@ 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);
+ nfsd_file_put(nf);
+ if (IS_ERR(dd)) {
+ int err = PTR_ERR(dd);
+
+ if (err != -EAGAIN)
+ return nfserrno(err);
+ gdd->gddrnf_status = GDD4_UNAVAIL;
+ return nfs_ok;
+ }
+
+ 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 da66798023aba4c36c38208cec7333db237e46e0..8f8c9385101e15b64883eabec71775f26b14f890 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -9347,3 +9347,103 @@ 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 = nfsd_file_get(nf);
+ fp->fi_delegees = 1;
+ } else {
+ ++fp->fi_delegees;
+ }
+ 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 */

--
2.51.1