nfsd: make 'boot_time' 64-bit wide

The local boot time variable gets truncated to time_t at the moment,
which can lead to slightly odd behavior on 32-bit architectures.

Use ktime_get_real_seconds() instead of get_seconds() to always
get a 64-bit result, and keep it that way wherever possible.

It still gets truncated in a few places:

- When assigning to cl_clientid.cl_boot, this is already documented
  and is only used as a unique identifier.

- In clients_still_reclaiming(), the truncation is to 'unsigned long'
  in order to use the 'time_before() helper.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/netns.h

@@ -40,7 +40,7 @@ struct nfsd_net {
 
 	struct lock_manager nfsd4_manager;
 	bool grace_ended;
-	time_t boot_time;
+	time64_t boot_time;
 
 	/* internal mount of the "nfsd" pseudofilesystem: */
 	struct vfsmount *nfsd_mnt;

fs/nfsd/nfs4recover.c

@@ -1445,7 +1445,7 @@ nfsd4_cld_grace_done_v0(struct nfsd_net *nn)
 	}
 
 	cup->cu_u.cu_msg.cm_cmd = Cld_GraceDone;
-	cup->cu_u.cu_msg.cm_u.cm_gracetime = (int64_t)nn->boot_time;
+	cup->cu_u.cu_msg.cm_u.cm_gracetime = nn->boot_time;
 	ret = cld_pipe_upcall(cn->cn_pipe, &cup->cu_u.cu_msg);
 	if (!ret)
 		ret = cup->cu_u.cu_msg.cm_status;
@@ -1782,7 +1782,7 @@ nfsd4_cltrack_client_has_session(struct nfs4_client *clp)
 }
 
 static char *
-nfsd4_cltrack_grace_start(time_t grace_start)
+nfsd4_cltrack_grace_start(time64_t grace_start)
 {
 	int copied;
 	size_t len;
@@ -1795,7 +1795,7 @@ nfsd4_cltrack_grace_start(time_t grace_start)
 	if (!result)
 		return result;
 
-	copied = snprintf(result, len, GRACE_START_ENV_PREFIX "%ld",
+	copied = snprintf(result, len, GRACE_START_ENV_PREFIX "%lld",
 				grace_start);
 	if (copied >= len) {
 		/* just return nothing if output was truncated */
@@ -2004,7 +2004,7 @@ nfsd4_umh_cltrack_grace_done(struct nfsd_net *nn)
 	char *legacy;
 	char timestr[22]; /* FIXME: better way to determine max size? */
 
-	sprintf(timestr, "%ld", nn->boot_time);
+	sprintf(timestr, "%lld", nn->boot_time);
 	legacy = nfsd4_cltrack_legacy_topdir();
 	nfsd4_umh_cltrack_upcall("gracedone", timestr, legacy, NULL);
 	kfree(legacy);

fs/nfsd/nfs4state.c

@@ -748,7 +748,7 @@ static int nfs4_init_cp_state(struct nfsd_net *nn, copy_stateid_t *stid,
 {
 	int new_id;
 
-	stid->stid.si_opaque.so_clid.cl_boot = nn->boot_time;
+	stid->stid.si_opaque.so_clid.cl_boot = (u32)nn->boot_time;
 	stid->stid.si_opaque.so_clid.cl_id = nn->s2s_cp_cl_id;
 	stid->sc_type = sc_type;
 
@@ -1911,7 +1911,7 @@ STALE_CLIENTID(clientid_t *clid, struct nfsd_net *nn)
 	 */
 	if (clid->cl_boot == (u32)nn->boot_time)
 		return 0;
-	dprintk("NFSD stale clientid (%08x/%08x) boot_time %08lx\n",
+	dprintk("NFSD stale clientid (%08x/%08x) boot_time %08llx\n",
 		clid->cl_boot, clid->cl_id, nn->boot_time);
 	return 1;
 }
@@ -2271,7 +2271,7 @@ static void gen_confirm(struct nfs4_client *clp, struct nfsd_net *nn)
 
 static void gen_clid(struct nfs4_client *clp, struct nfsd_net *nn)
 {
-	clp->cl_clientid.cl_boot = nn->boot_time;
+	clp->cl_clientid.cl_boot = (u32)nn->boot_time;
 	clp->cl_clientid.cl_id = nn->clientid_counter++;
 	gen_confirm(clp, nn);
 }
@@ -5233,9 +5233,9 @@ nfsd4_end_grace(struct nfsd_net *nn)
  */
 static bool clients_still_reclaiming(struct nfsd_net *nn)
 {
-	unsigned long now = get_seconds();
-	unsigned long double_grace_period_end = nn->boot_time +
-						2 * nn->nfsd4_lease;
+	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;
 
 	if (nn->track_reclaim_completes &&
 			atomic_read(&nn->nr_reclaim_complete) ==
@@ -7792,7 +7792,7 @@ static int nfs4_state_create_net(struct net *net)
 		INIT_LIST_HEAD(&nn->sessionid_hashtbl[i]);
 	nn->conf_name_tree = RB_ROOT;
 	nn->unconf_name_tree = RB_ROOT;
-	nn->boot_time = get_seconds();
+	nn->boot_time = ktime_get_real_seconds();
 	nn->grace_ended = false;
 	nn->nfsd4_manager.block_opens = true;
 	INIT_LIST_HEAD(&nn->nfsd4_manager.list);