[PATCH 15/19] nfsd: reject reclaim LOCK after RECLAIM_COMPLETE

[Jeff Layton <jlayton@kernel.org>]

nfsd4_lock() only checks the namespace-wide grace flag when deciding
whether to accept a reclaim LOCK. It does not check the per-client
NFSD4_CLIENT_RECLAIM_COMPLETE bit. A NFSv4.1+ client that has
already sent RECLAIM_COMPLETE can submit lk_reclaim=1 while grace is
still active (e.g. lockd holds the grace list open), and the server
accepts it instead of returning NFS4ERR_NO_GRACE as required by
RFC 8881 section 8.4.2.1.

The OPEN path already has the correct two-tier guard via
nfs4_check_open_reclaim(). Add the equivalent check to the LOCK path.

Fixes: 3b3e7b72239a ("nfsd: reject reclaim request when client has already sent RECLAIM_COMPLETE")
Assisted-by: Claude:claude-opus-4-8
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 fs/nfsd/nfs4state.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index fddef6f8db7c..7d96bffd2fd5 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -8552,6 +8552,9 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	status = nfserr_no_grace;
 	if (!locks_in_grace(net) && lock->lk_reclaim)
 		goto out;
+	if (lock->lk_reclaim &&
+	    test_bit(NFSD4_CLIENT_RECLAIM_COMPLETE, &cstate->clp->cl_flags))
+		goto out;
 
 	if (lock->lk_reclaim)
 		flags |= FL_RECLAIM;

-- 
2.54.0