[PATCH 14/19] nfsd: use test_and_clear_bit for somebody_reclaimed to prevent lost update

[Jeff Layton]

clients_still_reclaiming() uses separate test_bit() and clear_bit()
calls on NFSD_NET_SOMEBODY_RECLAIMED. A concurrent set_bit() from
the OPEN or LOCK reclaim path arriving between the test and clear
is silently lost, causing the next laundromat tick to end grace
prematurely.

Replace with test_and_clear_bit() to make the read-and-clear atomic.

Fixes: 8c67a210c90c ("nfsd: convert nfsd_net boolean flags to unsigned long flags word")
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
 fs/nfsd/nfs4state.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 6e47330c6365..fddef6f8db7c 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -6837,9 +6837,8 @@ static bool clients_still_reclaiming(struct nfsd_net *nn)
 		if (atomic_read(&nn->nr_reclaim_complete) == size)
 			return false;
 	}
-	if (!test_bit(NFSD_NET_SOMEBODY_RECLAIMED, &nn->flags))
+	if (!test_and_clear_bit(NFSD_NET_SOMEBODY_RECLAIMED, &nn->flags))
 		return false;
-	clear_bit(NFSD_NET_SOMEBODY_RECLAIMED, &nn->flags);
 	/*
 	 * If we've given them *two* lease times to reclaim, and they're
 	 * still not done, give up:

-- 
2.54.0