From: NeilBrown <neilb@suse.de>
Subject: Fix error in kabi fix for: NFSv4: Fix OPEN / CLOSE race
References: bsc#1176950, bsc#1217525
Patch-mainline: Never, kabi

As we now use a shared waitqueue, we could get extra wakeups.  In the
worst case we could get spurious wakeups at shorter intervals than 5*HZ,
so we never seem to timeout, and so loop indefinitely.

So calculate the expected deadline time, and once we pass that time,
assume a timeout.

Do this in other places that we wait on the waitqueue.

Signed-off-by: NeilBrown <neilb@suse.com>
---
 fs/nfs/nfs4proc.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1517,6 +1517,7 @@ static void nfs_clear_open_stateid(struc
 static void nfs_set_open_stateid_locked(struct nfs4_state *state,
 		const nfs4_stateid *stateid, nfs4_stateid *freeme)
 {
+	unsigned long deadline = jiffies + 5 * HZ;
 	DEFINE_WAIT(wait);
 	struct wait_queue_head *wq_head = bit_waitqueue(&state->flags,
 							NFS_STATE_CHANGE_WAIT);
@@ -1544,7 +1545,8 @@ static void nfs_set_open_stateid_locked(
 		rcu_read_unlock();
 
 		if (!fatal_signal_pending(current)) {
-			if (schedule_timeout(5*HZ) == 0)
+			if (schedule_timeout(5*HZ) == 0 ||
+			    time_after(jiffies, deadline))
 				status = -EAGAIN;
 			else
 				status = 0;
@@ -3191,6 +3193,8 @@ static bool nfs4_refresh_open_old_statei
 	u32 dst_seqid;
 	bool ret;
 	int seq, status = -EAGAIN;
+	unsigned long deadline = jiffies + 5 * HZ;
+
 	DEFINE_WAIT(wait);
 
 	for (;;) {
@@ -3223,10 +3227,12 @@ static bool nfs4_refresh_open_old_statei
 		write_sequnlock(&state->seqlock);
 		trace_nfs4_close_stateid_update_wait(state->inode, dst, 0);
 
+		status = -EAGAIN;
 		if (fatal_signal_pending(current))
 			status = -EINTR;
 		else
-			if (schedule_timeout(5*HZ) != 0)
+			if (schedule_timeout(5*HZ) != 0 &&
+			    !time_after(jiffies, deadline))
 				status = 0;
 
 		finish_wait(&state->waitq, &wait);