Re: [Y2038] [PATCH v2 10/12] nfsd: use boottime for lease expiry alculation

Hi Arnd-

On Dec 13, 2019, at 9:10 AM, Arnd Bergmann arnd@arndb.de wrote:

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.

Signed-off-by: Arnd Bergmann arnd@arndb.de

fs/nfsd/netns.h | 4 ++-- fs/nfsd/nfs4callback.c | 7 ++++++- fs/nfsd/nfs4state.c | 41 +++++++++++++++++++---------------------- fs/nfsd/nfsctl.c | 6 +++--- fs/nfsd/state.h | 8 ++++---- 5 files changed, 34 insertions(+), 32 deletions(-)

diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h index 29bbe28eda53..2baf32311e00 100644 --- a/fs/nfsd/netns.h +++ b/fs/nfsd/netns.h @@ -92,8 +92,8 @@ struct nfsd_net { 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;

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c index 24534db87e86..508d7c6c00b5 100644 --- a/fs/nfsd/nfs4callback.c +++ b/fs/nfsd/nfs4callback.c @@ -823,7 +823,12 @@ static const struct rpc_program cb_program = { 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 */
• if (WARN_ON_ONCE(nn->nfsd4_lease > 3600))

• return 360 * HZ;
  

Why is the WARN_ON_ONCE added here? Is it really necessary?

(Otherwise these all LGTM).

• return max(((u32)nn->nfsd4_lease)/10, 1u) * HZ;

}

static struct workqueue_struct *callback_wq; diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 9a063c4b4460..6afdef63f6d7 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -170,7 +170,7 @@ 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) @@ -2612,7 +2612,7 @@ 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));

@@ -4282,7 +4282,7 @@ 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);

@@ -4377,7 +4377,7 @@ 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);

@@ -5183,9 +5183,8 @@ 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) ==

@@ -5198,12 +5197,12 @@ 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; @@ -5212,8 +5211,8 @@ 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;

  dprintk("NFSD: laundromat service - starting\n");

@@ -5227,7 +5226,7 @@ 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;
  

@@ -5250,7 +5249,7 @@ 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;
  

@@ -5270,8 +5269,7 @@ 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;
  

@@ -5301,8 +5299,7 @@ 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;
  

@@ -5319,7 +5316,7 @@ 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;

}

@@ -5329,13 +5326,13 @@ 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);

}

@@ -6549,7 +6546,7 @@ 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);

@@ -7709,7 +7706,7 @@ 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;

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 11b42c523f04..aace740d5a92 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -956,7 +956,7 @@ static ssize_t write_maxconn(struct file *file, char *buf, size_t size)

#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; @@ -984,11 +984,11 @@ static ssize_t __nfsd4_write_time(struct file *file, char *buf, size_t size, *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;

diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h index 03fc7b4380f9..e426b22b5028 100644 --- a/fs/nfsd/state.h +++ b/fs/nfsd/state.h @@ -132,7 +132,7 @@ struct nfs4_delegation { 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; @@ -310,7 +310,7 @@ struct nfs4_client { #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 */

@@ -449,7 +449,7 @@ struct nfs4_openowner { */ 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; }; @@ -606,7 +606,7 @@ static inline bool nfsd4_stateid_generation_after(stateid_t *a, stateid_t *b) 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;

-- 2.20.0

-- Chuck Lever