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 <arnd@arndb.de>
[bfields@redhat.com: fix up copy expiration]
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 22 insertions, 26 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index f680b1530f38..1ad68b49a101 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -171,7 +171,7 @@ renew_client_locked(struct nfs4_client *clp)
 			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)
@@ -776,7 +776,7 @@ struct nfs4_cpntf_state *nfs4_alloc_init_cpntf_state(struct nfsd_net *nn,
 	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;
@@ -2661,7 +2661,7 @@ static struct nfs4_client *create_client(struct xdr_netobj name,
 	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));
@@ -4331,7 +4331,7 @@ move_to_close_lru(struct nfs4_ol_stateid *s, struct net *net)
 	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);
@@ -4426,7 +4426,7 @@ static void nfsd4_cb_recall_prepare(struct nfsd4_callback *cb)
 	 */
 	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);
@@ -5233,9 +5233,8 @@ nfsd4_end_grace(struct nfsd_net *nn)
  */
 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) ==
@@ -5248,12 +5247,12 @@ static bool clients_still_reclaiming(struct nfsd_net *nn)
 	 * 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;
@@ -5262,8 +5261,8 @@ nfs4_laundromat(struct nfsd_net *nn)
 	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;
@@ -5282,8 +5281,7 @@ nfs4_laundromat(struct nfsd_net *nn)
 	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);
@@ -5291,7 +5289,7 @@ nfs4_laundromat(struct nfsd_net *nn)
 	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;
@@ -5314,7 +5312,7 @@ nfs4_laundromat(struct nfsd_net *nn)
 	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;
@@ -5334,8 +5332,7 @@ nfs4_laundromat(struct nfsd_net *nn)
 	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;
@@ -5365,8 +5362,7 @@ nfs4_laundromat(struct nfsd_net *nn)
 	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;
@@ -5383,7 +5379,7 @@ nfs4_laundromat(struct nfsd_net *nn)
 		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;
 }
 
@@ -5393,13 +5389,13 @@ static void laundromat_main(struct work_struct *);
 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);
 }
 
@@ -5723,7 +5719,7 @@ static __be32 find_cpntf_state(struct nfsd_net *nn, stateid_t *st,
 	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)
@@ -6700,7 +6696,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	}
 
 	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);
@@ -7861,7 +7857,7 @@ nfs4_state_start_net(struct net *net)
 	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;