linux-kernel - [PATCH 16/19] nfsd: fix jiffies/time

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Date:   Mon, 11 Nov 2019 21:16:36 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     linux-nfs@...r.kernel.org,
        "J. Bruce Fields" <bfields@...ldses.org>,
        Chuck Lever <chuck.lever@...cle.com>,
        Trond Myklebust <trond.myklebust@...merspace.com>,
        Anna Schumaker <anna.schumaker@...app.com>
Cc:     y2038@...ts.linaro.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>
Subject: [PATCH 16/19] nfsd: fix jiffies/time_t mixup in LRU list

The nfsd4_blocked_lock->nbl_time timestamp is recorded in jiffies,
but then compared to a CLOCK_REALTIME timestamp later on, which makes
no sense.

For consistency with the other timestamps, change this to use a time_t.

This is a change in behavior, which may cause regressions, but the
current code is not sensible. On a system with CONFIG_HZ=1000,
the 'time_after((unsigned long)nbl->nbl_time, (unsigned long)cutoff))'
check is false for roughly the first 18 days of uptime and then true
for the next 49 days.

Fixes: 7919d0a27f1e ("nfsd: add a LRU list for blocked locks")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 fs/nfsd/nfs4state.c | 2 +-
 fs/nfsd/state.h     | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 1ea7a40f8d4e..551068f4b836 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -6544,7 +6544,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	}
 
 	if (fl_flags & FL_SLEEP) {
-		nbl->nbl_time = jiffies;
+		nbl->nbl_time = get_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);
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index ce32ba445343..c1bb6a5ecf57 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -605,7 +605,7 @@ 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;
-	unsigned long		nbl_time;
+	time_t			nbl_time;
 	struct file_lock	nbl_lock;
 	struct knfsd_fh		nbl_fh;
 	struct nfsd4_callback	nbl_cb;
-- 
2.20.0