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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Donald Buczek <buczek@molgen.mpg.de>,
        "J. Bruce Fields" <bfields@redhat.com>
Subject: [PATCH 4.20 69/92] Revert "nfsd4: return default lease period"
Date:   Mon, 18 Feb 2019 14:43:12 +0100
Message-Id: <20190218133501.348145285@linuxfoundation.org>
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4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: J. Bruce Fields <bfields@redhat.com>

commit 3bf6b57ec2ec945e5a6edf5c202a754f1e852ecd upstream.

This reverts commit d6ebf5088f09472c1136cd506bdc27034a6763f8.

I forgot that the kernel's default lease period should never be
decreased!

After a kernel upgrade, the kernel has no way of knowing on its own what
the previous lease time was.  Unless userspace tells it otherwise, it
will assume the previous lease period was the same.

So if we decrease this value in a kernel upgrade, we end up enforcing a
grace period that's too short, and clients will fail to reclaim state in
time.  Symptoms may include EIO and log messages like "NFS:
nfs4_reclaim_open_state: Lock reclaim failed!"

There was no real justification for the lease period decrease anyway.

Reported-by: Donald Buczek <buczek@molgen.mpg.de>
Fixes: d6ebf5088f09 "nfsd4: return default lease period"
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/nfsd/nfsctl.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -1239,8 +1239,8 @@ static __net_init int nfsd_init_net(stru
 	retval = nfsd_idmap_init(net);
 	if (retval)
 		goto out_idmap_error;
-	nn->nfsd4_lease = 45;	/* default lease time */
-	nn->nfsd4_grace = 45;
+	nn->nfsd4_lease = 90;	/* default lease time */
+	nn->nfsd4_grace = 90;
 	nn->somebody_reclaimed = false;
 	nn->clverifier_counter = prandom_u32();
 	nn->clientid_counter = prandom_u32();