nfsd4: cleanup handling of nfsv4.0 closed stateid's

Closed stateid's are kept around a little while to handle close replays
in the 4.0 case.  So we stash them in the last-used stateid in the
oo_last_closed_stateid field of the open owner.  We can free that in
encode_seqid_op_tail once the seqid on the open owner is next
incremented.  But we don't want to do that on the close itself; so we
set NFS4_OO_PURGE_CLOSE flag set on the open owner, skip freeing it the
first time through encode_seqid_op_tail, then when we see that flag set
next time we free it.

This is unnecessarily baroque.

Instead, just move the logic that increments the seqid out of the xdr
code and into the operation code itself.

The justification given for the current placement is that we need to
wait till the last minute to be sure we know whether the status is a
sequence-id-mutating error or not, but examination of the code shows
that can't actually happen.
Reported-by: NYanchuan Nian <ycnian@gmail.com>
Tested-by: NYanchuan Nian <ycnian@gmail.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4proc.c

@@ -415,7 +415,8 @@ nfsd4_open(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	nfsd4_cleanup_open_state(open, status);
 	if (open->op_openowner)
 		cstate->replay_owner = &open->op_openowner->oo_owner;
-	else
+	nfsd4_bump_seqid(cstate, status);
+	if (!cstate->replay_owner)
 		nfs4_unlock_state();
 	return status;
 }

fs/nfsd/nfs4state.c

@@ -720,6 +720,28 @@ dump_sessionid(const char *fn, struct nfs4_sessionid *sessionid)
 }
 #endif
 
+/*
+ * Bump the seqid on cstate->replay_owner, and clear replay_owner if it
+ * won't be used for replay.
+ */
+void nfsd4_bump_seqid(struct nfsd4_compound_state *cstate, __be32 nfserr)
+{
+	struct nfs4_stateowner *so = cstate->replay_owner;
+
+	if (nfserr == nfserr_replay_me)
+		return;
+
+	if (!seqid_mutating_err(ntohl(nfserr))) {
+		cstate->replay_owner = NULL;
+		return;
+	}
+	if (!so)
+		return;
+	if (so->so_is_open_owner)
+		release_last_closed_stateid(openowner(so));
+	so->so_seqid++;
+	return;
+}
 
 static void
 gen_sessionid(struct nfsd4_session *ses)
@@ -3702,6 +3724,7 @@ nfsd4_open_confirm(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	nfsd4_client_record_create(oo->oo_owner.so_client);
 	status = nfs_ok;
 out:
+	nfsd4_bump_seqid(cstate, status);
 	if (!cstate->replay_owner)
 		nfs4_unlock_state();
 	return status;
@@ -3785,31 +3808,12 @@ nfsd4_open_downgrade(struct svc_rqst *rqstp,
 	memcpy(&od->od_stateid, &stp->st_stid.sc_stateid, sizeof(stateid_t));
 	status = nfs_ok;
 out:
+	nfsd4_bump_seqid(cstate, status);
 	if (!cstate->replay_owner)
 		nfs4_unlock_state();
 	return status;
 }
 
-void nfsd4_purge_closed_stateid(struct nfs4_stateowner *so)
-{
-	struct nfs4_openowner *oo;
-	struct nfs4_ol_stateid *s;
-
-	if (!so->so_is_open_owner)
-		return;
-	oo = openowner(so);
-	s = oo->oo_last_closed_stid;
-	if (!s)
-		return;
-	if (!(oo->oo_flags & NFS4_OO_PURGE_CLOSE)) {
-		/* Release the last_closed_stid on the next seqid bump: */
-		oo->oo_flags |= NFS4_OO_PURGE_CLOSE;
-		return;
-	}
-	oo->oo_flags &= ~NFS4_OO_PURGE_CLOSE;
-	release_last_closed_stateid(oo);
-}
-
 static void nfsd4_close_open_stateid(struct nfs4_ol_stateid *s)
 {
 	unhash_open_stateid(s);
@@ -3838,17 +3842,20 @@ nfsd4_close(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 					&close->cl_stateid,
 					NFS4_OPEN_STID|NFS4_CLOSED_STID,
 					&stp, nn);
+	nfsd4_bump_seqid(cstate, status);
 	if (status)
 		goto out; 
 	oo = openowner(stp->st_stateowner);
-	status = nfs_ok;
 	update_stateid(&stp->st_stid.sc_stateid);
 	memcpy(&close->cl_stateid, &stp->st_stid.sc_stateid, sizeof(stateid_t));
 
 	nfsd4_close_open_stateid(stp);
-	release_last_closed_stateid(oo);
-	oo->oo_flags &= ~NFS4_OO_PURGE_CLOSE;
-	oo->oo_last_closed_stid = stp;
+
+	if (cstate->minorversion) {
+		unhash_stid(&stp->st_stid);
+		free_generic_stateid(stp);
+	} else
+		oo->oo_last_closed_stid = stp;
 
 	if (list_empty(&oo->oo_owner.so_stateids)) {
 		if (cstate->minorversion) {
@@ -4270,6 +4277,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 out:
 	if (status && new_state)
 		release_lockowner(lock_sop);
+	nfsd4_bump_seqid(cstate, status);
 	if (!cstate->replay_owner)
 		nfs4_unlock_state();
 	if (file_lock)
@@ -4439,6 +4447,7 @@ nfsd4_locku(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	memcpy(&locku->lu_stateid, &stp->st_stid.sc_stateid, sizeof(stateid_t));
 
 out:
+	nfsd4_bump_seqid(cstate, status);
 	if (!cstate->replay_owner)
 		nfs4_unlock_state();
 	if (file_lock)

fs/nfsd/nfs4xdr.c

@@ -1701,28 +1701,6 @@ static void write_cinfo(__be32 **p, struct nfsd4_change_info *c)
 								\
 	save = resp->p;
 
-/*
- * Routine for encoding the result of a "seqid-mutating" NFSv4 operation.  This
- * is where sequence id's are incremented, and the replay cache is filled.
- * Note that we increment sequence id's here, at the last moment, so we're sure
- * we know whether the error to be returned is a sequence id mutating error.
- */
-
-static void encode_seqid_op_tail(struct nfsd4_compoundres *resp, __be32 *save, __be32 nfserr)
-{
-	struct nfs4_stateowner *stateowner = resp->cstate.replay_owner;
-
-	if (seqid_mutating_err(ntohl(nfserr)) && stateowner) {
-		stateowner->so_seqid++;
-		stateowner->so_replay.rp_status = nfserr;
-		stateowner->so_replay.rp_buflen =
-			  (char *)resp->p - (char *)save;
-		memcpy(stateowner->so_replay.rp_buf, save,
-			stateowner->so_replay.rp_buflen);
-		nfsd4_purge_closed_stateid(stateowner);
-	}
-}
-
 /* Encode as an array of strings the string given with components
  * separated @sep, escaped with esc_enter and esc_exit.
  */
@@ -2667,7 +2645,6 @@ nfsd4_encode_close(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_c
 	if (!nfserr)
 		nfsd4_encode_stateid(resp, &close->cl_stateid);
 
-	encode_seqid_op_tail(resp, save, nfserr);
 	return nfserr;
 }
 
@@ -2770,7 +2747,6 @@ nfsd4_encode_lock(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_lo
 	else if (nfserr == nfserr_denied)
 		nfsd4_encode_lock_denied(resp, &lock->lk_denied);
 
-	encode_seqid_op_tail(resp, save, nfserr);
 	return nfserr;
 }
 
@@ -2790,7 +2766,6 @@ nfsd4_encode_locku(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_l
 	if (!nfserr)
 		nfsd4_encode_stateid(resp, &locku->lu_stateid);
 
-	encode_seqid_op_tail(resp, save, nfserr);
 	return nfserr;
 }
 
@@ -2885,7 +2860,6 @@ nfsd4_encode_open(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_op
 	}
 	/* XXX save filehandle here */
 out:
-	encode_seqid_op_tail(resp, save, nfserr);
 	return nfserr;
 }
 
@@ -2897,7 +2871,6 @@ nfsd4_encode_open_confirm(struct nfsd4_compoundres *resp, __be32 nfserr, struct
 	if (!nfserr)
 		nfsd4_encode_stateid(resp, &oc->oc_resp_stateid);
 
-	encode_seqid_op_tail(resp, save, nfserr);
 	return nfserr;
 }
 
@@ -2909,7 +2882,6 @@ nfsd4_encode_open_downgrade(struct nfsd4_compoundres *resp, __be32 nfserr, struc
 	if (!nfserr)
 		nfsd4_encode_stateid(resp, &od->od_stateid);
 
-	encode_seqid_op_tail(resp, save, nfserr);
 	return nfserr;
 }
 
@@ -3567,6 +3539,7 @@ __be32 nfsd4_check_resp_size(struct nfsd4_compoundres *resp, u32 pad)
 void
 nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op)
 {
+	struct nfs4_stateowner *so = resp->cstate.replay_owner;
 	__be32 *statp;
 	__be32 *p;
 
@@ -3583,6 +3556,11 @@ nfsd4_encode_operation(struct nfsd4_compoundres *resp, struct nfsd4_op *op)
 	/* nfsd4_check_drc_limit guarantees enough room for error status */
 	if (!op->status)
 		op->status = nfsd4_check_resp_size(resp, 0);
+	if (so) {
+		so->so_replay.rp_status = op->status;
+		so->so_replay.rp_buflen = (char *)resp->p - (char *)(statp+1);
+		memcpy(so->so_replay.rp_buf, statp+1, so->so_replay.rp_buflen);
+	}
 status:
 	/*
 	 * Note: We write the status directly, instead of using WRITE32(),

fs/nfsd/state.h

@@ -355,7 +355,6 @@ struct nfs4_openowner {
 	struct nfs4_ol_stateid *oo_last_closed_stid;
 	time_t			oo_time; /* time of placement on so_close_lru */
 #define NFS4_OO_CONFIRMED   1
-#define NFS4_OO_PURGE_CLOSE 2
 #define NFS4_OO_NEW         4
 	unsigned char		oo_flags;
 };
@@ -363,7 +362,7 @@ struct nfs4_openowner {
 struct nfs4_lockowner {
 	struct nfs4_stateowner	lo_owner; /* must be first element */
 	struct list_head	lo_owner_ino_hash; /* hash by owner,file */
-	struct list_head        lo_perstateid; /* for lockowners only */
+	struct list_head        lo_perstateid;
 	struct list_head	lo_list; /* for temporary uses */
 };
 
@@ -477,7 +476,6 @@ extern struct nfs4_client_reclaim *nfs4_client_to_reclaim(const char *name,
 							struct nfsd_net *nn);
 extern bool nfs4_has_reclaimed_state(const char *name, struct nfsd_net *nn);
 extern void put_client_renew(struct nfs4_client *clp);
-extern void nfsd4_purge_closed_stateid(struct nfs4_stateowner *);
 
 /* nfs4recover operations */
 extern int nfsd4_client_tracking_init(struct net *net);

fs/nfsd/xdr4.h

@@ -623,6 +623,7 @@ extern __be32 nfsd4_test_stateid(struct svc_rqst *rqstp,
 		struct nfsd4_compound_state *, struct nfsd4_test_stateid *test_stateid);
 extern __be32 nfsd4_free_stateid(struct svc_rqst *rqstp,
 		struct nfsd4_compound_state *, struct nfsd4_free_stateid *free_stateid);
+extern void nfsd4_bump_seqid(struct nfsd4_compound_state *, __be32 nfserr);
 #endif
 
 /*