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Subject: [PATCH 2/2] NFSv4.1: Fix bug only the first CB_NOTIFY_LOCK is handled
From:   Yihao Wu <wuyihao@linux.alibaba.com>
To:     linux-nfs@vger.kernel.org, Jeff Layton <jlayton@kernel.org>,
        "J. Bruce Fields" <bfields@fieldses.org>
Cc:     stable@vger.kernel.org, Joseph Qi <joseph.qi@linux.alibaba.com>,
        caspar@linux.alibaba.com
References: <d0b6fc01-0a73-e4f7-b393-3ecc9aacffb0@linux.alibaba.com>
 <2a1cebca-1efb-1686-475b-a581e50e61b4@linux.alibaba.com>
Message-ID: <cdba66b5-29a3-e37b-1e0f-808c171d09c3@linux.alibaba.com>
Date:   Wed, 8 May 2019 17:15:03 +0800
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When the first CB_NOTIFY_LOCK wakes a waiter, it can still fail to
acquire the lock. Then it might goes to sleep again. However it's removed
from the wait queue and not put back. So when the CB_NOTIFY_LOCK comes
again, it fails to wake this waiter.

Signed-off-by: Yihao Wu <wuyihao@linux.alibaba.com>
---
 fs/nfs/nfs4proc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index f13ea09..9de2c2d 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6932,6 +6932,10 @@ struct nfs4_lock_waiter {
 
 		status = -ERESTARTSYS;
 		wait_woken(&wait, TASK_INTERRUPTIBLE, NFS4_LOCK_MAXTIMEOUT);
+		if (!signalled())  {
+			finish_wait(q, &wait);
+			add_wait_queue(q, &wait);
+		}
 	}
 
 	finish_wait(q, &wait);
-- 
1.8.3.1