nfsd: drop dead COPY-vs-COPYNOTIFY type handling from s2s stateid IDR

Now that the COPY offload stateid is a first-class nfs4_stid,
nn->s2s_cp_stateids holds COPY_NOTIFY stateids exclusively (its only
inserter, nfs4_init_cp_state(), runs only from
nfs4_alloc_init_cpntf_state()). The type-distinguishing machinery is dead:

  - remove the unreferenced NFS4_COPY_STID definition;

  - drop nfs4_init_cp_state()'s cs_type argument (hardcode
    NFS4_COPYNOTIFY_STID) and its now-always-true "if (p_stid)" guard;

  - remove the cs_type == NFS4_COPYNOTIFY_STID gates in
    manage_cpntf_state() and the laundromat, which can no longer be false.

copy_stateid_t.cs_type is retained for the WARN_ON_ONCE() sanity checks on
the free paths. No functional change.

Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260710-nfsd-testing-v3-10-a0ff7db6aa3e@kernel.org
Signed-off-by: Chuck Lever <cel@kernel.org>

2 files changed, 12 insertions, 19 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 015a67abd1e7..0976da2508ce 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -979,10 +979,11 @@ out_free:
 }
 
 /*
- * Create a unique stateid_t to represent each COPY.
+ * Publish a COPY_NOTIFY stateid in nn->s2s_cp_stateids and link it onto the
+ * parent's sc_cp_list. That IDR holds only COPY_NOTIFY stateids.
  */
 static int nfs4_init_cp_state(struct nfsd_net *nn, copy_stateid_t *stid,
-			      unsigned char cs_type, struct nfs4_stid *p_stid)
+			      struct nfs4_stid *p_stid)
 {
 	int new_id;
 
@@ -993,6 +994,9 @@ static int nfs4_init_cp_state(struct nfsd_net *nn, copy_stateid_t *stid,
 	spin_lock(&nn->s2s_cp_lock);
 	new_id = idr_alloc_cyclic(&nn->s2s_cp_stateids, stid, 0, 0, GFP_NOWAIT);
 	if (new_id >= 0) {
+		struct nfs4_cpntf_state *cps =
+			container_of(stid, struct nfs4_cpntf_state, cp_stateid);
+
 		stid->cs_stid.si_opaque.so_id = new_id;
 		stid->cs_stid.si_generation = 1;
 		/*
@@ -1001,14 +1005,8 @@ static int nfs4_init_cp_state(struct nfsd_net *nn, copy_stateid_t *stid,
 		 * manage_cpntf_state() sees either no entry or a fully
 		 * linked cp_list.
 		 */
-		stid->cs_type = cs_type;
-		if (p_stid) {
-			struct nfs4_cpntf_state *cps =
-				container_of(stid, struct nfs4_cpntf_state,
-					     cp_stateid);
-
-			list_add(&cps->cp_list, &p_stid->sc_cp_list);
-		}
+		stid->cs_type = NFS4_COPYNOTIFY_STID;
+		list_add(&cps->cp_list, &p_stid->sc_cp_list);
 	}
 	spin_unlock(&nn->s2s_cp_lock);
 	idr_preload_end();
@@ -1068,8 +1066,7 @@ struct nfs4_cpntf_state *nfs4_alloc_init_cpntf_state(struct nfsd_net *nn,
 	memcpy(&cps->cp_p_clid, &p_stid->sc_client->cl_clientid,
 	       sizeof(clientid_t));
 	refcount_set(&cps->cp_stateid.cs_count, 2);
-	if (!nfs4_init_cp_state(nn, &cps->cp_stateid, NFS4_COPYNOTIFY_STID,
-				p_stid))
+	if (!nfs4_init_cp_state(nn, &cps->cp_stateid, p_stid))
 		goto out_free;
 	return cps;
 out_free:
@@ -7635,10 +7632,10 @@ nfs4_laundromat(struct nfsd_net *nn)
 	nfsd4_end_grace(nn);
 
 	spin_lock(&nn->s2s_cp_lock);
+	/* s2s_cp_stateids holds only COPY_NOTIFY stateids */
 	idr_for_each_entry(&nn->s2s_cp_stateids, cps_t, i) {
 		cps = container_of(cps_t, struct nfs4_cpntf_state, cp_stateid);
-		if (cps->cp_stateid.cs_type == NFS4_COPYNOTIFY_STID &&
-				state_expired(&lt, cps->cpntf_time))
+		if (state_expired(&lt, cps->cpntf_time))
 			revoke_cpntf_state_locked(nn, cps);
 	}
 	spin_unlock(&nn->s2s_cp_lock);
@@ -8076,14 +8073,11 @@ __be32 manage_cpntf_state(struct nfsd_net *nn, stateid_t *st,
 	if (st->si_opaque.so_clid.cl_id != nn->s2s_cp_cl_id)
 		return nfserr_bad_stateid;
 	spin_lock(&nn->s2s_cp_lock);
+	/* s2s_cp_stateids holds only COPY_NOTIFY stateids */
 	cps_t = idr_find(&nn->s2s_cp_stateids, st->si_opaque.so_id);
 	if (cps_t) {
 		state = container_of(cps_t, struct nfs4_cpntf_state,
 				     cp_stateid);
-		if (state->cp_stateid.cs_type != NFS4_COPYNOTIFY_STID) {
-			state = NULL;
-			goto unlock;
-		}
 		if (!clp) {
 			refcount_inc(&state->cp_stateid.cs_count);
 		} else if (memcmp(&clp->cl_clientid, &state->cp_p_clid,
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index 5dc4a473246e..ee5c429edfa2 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -59,7 +59,6 @@ typedef struct {
 
 typedef struct {
 	stateid_t		cs_stid;
-#define NFS4_COPY_STID 1
 #define NFS4_COPYNOTIFY_STID 2
 	unsigned char		cs_type;
 	refcount_t		cs_count;