nfsd: use boottime for lease expiry calculation

A couple of time_t variables are only used to track the state of the
lease time and its expiration. The code correctly uses the 'time_after()'
macro to make this work on 32-bit architectures even beyond year 2038,
but the get_seconds() function and the time_t type itself are deprecated
as they behave inconsistently between 32-bit and 64-bit architectures
and often lead to code that is not y2038 safe.

As a minor issue, using get_seconds() leads to problems with concurrent
settimeofday() or clock_settime() calls, in the worst case timeout never
triggering after the time has been set backwards.

Change nfsd to use time64_t and ktime_get_boottime_seconds() here. This
is clearly excessive, as boottime by itself means we never go beyond 32
bits, but it does mean we handle this correctly and consistently without
having to worry about corner cases and should be no more expensive than
the previous implementation on 64-bit architectures.

The max_cb_time() function gets changed in order to avoid an expensive
64-bit division operation, but as the lease time is at most one hour,
there is no change in behavior.

Also do the same for server-to-server copy expiration time.

Signed-off-by: Arnd Bergmann <[e-mail]>
[[e-mail]: fix up copy expiration]
Signed-off-by: J. Bruce Fields <[e-mail]>

fs/nfsd/netns.h

···
 	bool in_grace;
 	const struct nfsd4_client_tracking_ops *client_tracking_ops;
 
-	time_t nfsd4_lease;
-	time_t nfsd4_grace;
+	time64_t nfsd4_lease;
+	time64_t nfsd4_grace;
 	bool somebody_reclaimed;
 
 	bool track_reclaim_completes;

fs/nfsd/nfs4callback.c

···
 static int max_cb_time(struct net *net)
 {
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
-	return max(nn->nfsd4_lease/10, (time_t)1) * HZ;
+
+	/*
+	 * nfsd4_lease is set to at most one hour in __nfsd4_write_time,
+	 * so we can use 32-bit math on it. Warn if that assumption
+	 * ever stops being true.
+	 */
+	if (WARN_ON_ONCE(nn->nfsd4_lease > 3600))
+		return 360 * HZ;
+
+	return max(((u32)nn->nfsd4_lease)/10, 1u) * HZ;
 }
 
 static struct workqueue_struct *callback_wq;

fs/nfsd/nfs4state.c

···
 			clp->cl_clientid.cl_boot,
 			clp->cl_clientid.cl_id);
 	list_move_tail(&clp->cl_lru, &nn->client_lru);
-	clp->cl_time = get_seconds();
+	clp->cl_time = ktime_get_boottime_seconds();
 }
 
 static void put_client_renew_locked(struct nfs4_client *clp)
···
 	cps = kzalloc(sizeof(struct nfs4_cpntf_state), GFP_KERNEL);
 	if (!cps)
 		return NULL;
-	cps->cpntf_time = get_seconds();
+	cps->cpntf_time = ktime_get_boottime_seconds();
 	refcount_set(&cps->cp_stateid.sc_count, 1);
 	if (!nfs4_init_cp_state(nn, &cps->cp_stateid, NFS4_COPYNOTIFY_STID))
 		goto out_free;
···
 	gen_clid(clp, nn);
 	kref_init(&clp->cl_nfsdfs.cl_ref);
 	nfsd4_init_cb(&clp->cl_cb_null, clp, NULL, NFSPROC4_CLNT_CB_NULL);
-	clp->cl_time = get_seconds();
+	clp->cl_time = ktime_get_boottime_seconds();
 	clear_bit(0, &clp->cl_cb_slot_busy);
 	copy_verf(clp, verf);
 	memcpy(&clp->cl_addr, sa, sizeof(struct sockaddr_storage));
···
 	last = oo->oo_last_closed_stid;
 	oo->oo_last_closed_stid = s;
 	list_move_tail(&oo->oo_close_lru, &nn->close_lru);
-	oo->oo_time = get_seconds();
+	oo->oo_time = ktime_get_boottime_seconds();
 	spin_unlock(&nn->client_lock);
 	if (last)
 		nfs4_put_stid(&last->st_stid);
···
 	 */
 	spin_lock(&state_lock);
 	if (dp->dl_time == 0) {
-		dp->dl_time = get_seconds();
+		dp->dl_time = ktime_get_boottime_seconds();
 		list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru);
 	}
 	spin_unlock(&state_lock);
···
  */
 static bool clients_still_reclaiming(struct nfsd_net *nn)
 {
-	unsigned long now = (unsigned long) ktime_get_real_seconds();
-	unsigned long double_grace_period_end = (unsigned long)nn->boot_time +
-					   2 * (unsigned long)nn->nfsd4_lease;
+	time64_t double_grace_period_end = nn->boot_time +
+					   2 * nn->nfsd4_lease;
 
 	if (nn->track_reclaim_completes &&
 			atomic_read(&nn->nr_reclaim_complete) ==
···
 	 * If we've given them *two* lease times to reclaim, and they're
 	 * still not done, give up:
 	 */
-	if (time_after(now, double_grace_period_end))
+	if (ktime_get_boottime_seconds() > double_grace_period_end)
 		return false;
 	return true;
 }
 
-static time_t
+static time64_t
 nfs4_laundromat(struct nfsd_net *nn)
 {
 	struct nfs4_client *clp;
···
 	struct nfs4_ol_stateid *stp;
 	struct nfsd4_blocked_lock *nbl;
 	struct list_head *pos, *next, reaplist;
-	time_t cutoff = get_seconds() - nn->nfsd4_lease;
-	time_t t, new_timeo = nn->nfsd4_lease;
+	time64_t cutoff = ktime_get_boottime_seconds() - nn->nfsd4_lease;
+	time64_t t, new_timeo = nn->nfsd4_lease;
 	struct nfs4_cpntf_state *cps;
 	copy_stateid_t *cps_t;
 	int i;
···
 	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.sc_type == NFS4_COPYNOTIFY_STID &&
-				!time_after((unsigned long)cps->cpntf_time,
-				(unsigned long)cutoff))
+				cps->cpntf_time > cutoff)
 			_free_cpntf_state_locked(nn, cps);
 	}
 	spin_unlock(&nn->s2s_cp_lock);
···
 	spin_lock(&nn->client_lock);
 	list_for_each_safe(pos, next, &nn->client_lru) {
 		clp = list_entry(pos, struct nfs4_client, cl_lru);
-		if (time_after((unsigned long)clp->cl_time, (unsigned long)cutoff)) {
+		if (clp->cl_time > cutoff) {
 			t = clp->cl_time - cutoff;
 			new_timeo = min(new_timeo, t);
 			break;
···
 	spin_lock(&state_lock);
 	list_for_each_safe(pos, next, &nn->del_recall_lru) {
 		dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
-		if (time_after((unsigned long)dp->dl_time, (unsigned long)cutoff)) {
+		if (dp->dl_time > cutoff) {
 			t = dp->dl_time - cutoff;
 			new_timeo = min(new_timeo, t);
 			break;
···
 	while (!list_empty(&nn->close_lru)) {
 		oo = list_first_entry(&nn->close_lru, struct nfs4_openowner,
 					oo_close_lru);
-		if (time_after((unsigned long)oo->oo_time,
-			       (unsigned long)cutoff)) {
+		if (oo->oo_time > cutoff) {
 			t = oo->oo_time - cutoff;
 			new_timeo = min(new_timeo, t);
 			break;
···
 	while (!list_empty(&nn->blocked_locks_lru)) {
 		nbl = list_first_entry(&nn->blocked_locks_lru,
 					struct nfsd4_blocked_lock, nbl_lru);
-		if (time_after((unsigned long)nbl->nbl_time,
-			       (unsigned long)cutoff)) {
+		if (nbl->nbl_time > cutoff) {
 			t = nbl->nbl_time - cutoff;
 			new_timeo = min(new_timeo, t);
 			break;
···
 		free_blocked_lock(nbl);
 	}
 out:
-	new_timeo = max_t(time_t, new_timeo, NFSD_LAUNDROMAT_MINTIMEOUT);
+	new_timeo = max_t(time64_t, new_timeo, NFSD_LAUNDROMAT_MINTIMEOUT);
 	return new_timeo;
 }
 
···
 static void
 laundromat_main(struct work_struct *laundry)
 {
-	time_t t;
+	time64_t t;
 	struct delayed_work *dwork = to_delayed_work(laundry);
 	struct nfsd_net *nn = container_of(dwork, struct nfsd_net,
 					   laundromat_work);
 
 	t = nfs4_laundromat(nn);
-	dprintk("NFSD: laundromat_main - sleeping for %ld seconds\n", t);
+	dprintk("NFSD: laundromat_main - sleeping for %lld seconds\n", t);
 	queue_delayed_work(laundry_wq, &nn->laundromat_work, t*HZ);
 }
 
···
 	if (status)
 		return status;
 
-	cps->cpntf_time = get_seconds();
+	cps->cpntf_time = ktime_get_boottime_seconds();
 	memset(&cstate, 0, sizeof(cstate));
 	status = lookup_clientid(&cps->cp_p_clid, &cstate, nn, true);
 	if (status)
···
 	}
 
 	if (fl_flags & FL_SLEEP) {
-		nbl->nbl_time = get_seconds();
+		nbl->nbl_time = ktime_get_boottime_seconds();
 		spin_lock(&nn->blocked_locks_lock);
 		list_add_tail(&nbl->nbl_list, &lock_sop->lo_blocked);
 		list_add_tail(&nbl->nbl_lru, &nn->blocked_locks_lru);
···
 	nfsd4_client_tracking_init(net);
 	if (nn->track_reclaim_completes && nn->reclaim_str_hashtbl_size == 0)
 		goto skip_grace;
-	printk(KERN_INFO "NFSD: starting %ld-second grace period (net %x)\n",
+	printk(KERN_INFO "NFSD: starting %lld-second grace period (net %x)\n",
 	       nn->nfsd4_grace, net->ns.inum);
 	queue_delayed_work(laundry_wq, &nn->laundromat_work, nn->nfsd4_grace * HZ);
 	return 0;

fs/nfsd/nfsctl.c

···
 
 #ifdef CONFIG_NFSD_V4
 static ssize_t __nfsd4_write_time(struct file *file, char *buf, size_t size,
-				  time_t *time, struct nfsd_net *nn)
+				  time64_t *time, struct nfsd_net *nn)
 {
 	char *mesg = buf;
 	int rv, i;
···
 		*time = i;
 	}
 
-	return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%ld\n", *time);
+	return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%lld\n", *time);
 }
 
 static ssize_t nfsd4_write_time(struct file *file, char *buf, size_t size,
-				time_t *time, struct nfsd_net *nn)
+				time64_t *time, struct nfsd_net *nn)
 {
 	ssize_t rv;
 

fs/nfsd/state.h

···
 	struct list_head	cp_list;	/* per parent nfs4_stid */
 	stateid_t		cp_p_stateid;	/* copy of parent's stateid */
 	clientid_t		cp_p_clid;	/* copy of parent's clid */
-	time_t			cpntf_time;	/* last time stateid used */
+	time64_t		cpntf_time;	/* last time stateid used */
 };
 
 /*
···
 	struct list_head	dl_recall_lru;  /* delegation recalled */
 	struct nfs4_clnt_odstate *dl_clnt_odstate;
 	u32			dl_type;
-	time_t			dl_time;
+	time64_t		dl_time;
 /* For recall: */
 	int			dl_retries;
 	struct nfsd4_callback	dl_recall;
···
 #endif
 	struct xdr_netobj	cl_name; 	/* id generated by client */
 	nfs4_verifier		cl_verifier; 	/* generated by client */
-	time_t                  cl_time;        /* time of last lease renewal */
+	time64_t		cl_time;	/* time of last lease renewal */
 	struct sockaddr_storage	cl_addr; 	/* client ipaddress */
 	bool			cl_mach_cred;	/* SP4_MACH_CRED in force */
 	struct svc_cred		cl_cred; 	/* setclientid principal */
···
 	 */
 	struct list_head	oo_close_lru;
 	struct nfs4_ol_stateid *oo_last_closed_stid;
-	time_t			oo_time; /* time of placement on so_close_lru */
+	time64_t		oo_time; /* time of placement on so_close_lru */
 #define NFS4_OO_CONFIRMED   1
 	unsigned char		oo_flags;
 };
···
 struct nfsd4_blocked_lock {
 	struct list_head	nbl_list;
 	struct list_head	nbl_lru;
-	time_t			nbl_time;
+	time64_t		nbl_time;
 	struct file_lock	nbl_lock;
 	struct knfsd_fh		nbl_fh;
 	struct nfsd4_callback	nbl_cb;