[PATCH RFC v16 04/11] NFSD: Update nfsd_breaker_owns_lease() to handle courtesy clients

[Dai Ngo <dai.ngo@oracle.com>]

Update nfsd_breaker_owns_lease() to handle delegation conflict
with courtesy clients. If conflict was caused by courtesy client
then discard the courtesy client by setting CLIENT_EXPIRED and
return conflict resolved. Client with CLIENT_EXPIRED is expired
by the laundromat.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 583ac807e98d..2beb0972de88 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4713,6 +4713,28 @@ nfsd_break_deleg_cb(struct file_lock *fl)
 	return ret;
 }
 
+static bool
+nfs4_check_and_expire_courtesy_client(struct nfs4_client *clp)
+{
+	/*
+	 * need to sync with courtesy client trying to reconnect using
+	 * the cl_cs_lock, nn->client_lock can not be used since this
+	 * function is called with the fl_lck held.
+	 */
+	spin_lock(&clp->cl_cs_lock);
+	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags)) {
+		spin_unlock(&clp->cl_cs_lock);
+		return true;
+	}
+	if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
+		set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
+		spin_unlock(&clp->cl_cs_lock);
+		return true;
+	}
+	spin_unlock(&clp->cl_cs_lock);
+	return false;
+}
+
 /**
  * nfsd_breaker_owns_lease - Check if lease conflict was resolved
  * @fl: Lock state to check
@@ -4727,6 +4749,10 @@ static bool nfsd_breaker_owns_lease(struct file_lock *fl)
 	struct svc_rqst *rqst;
 	struct nfs4_client *clp;
 
+	clp = dl->dl_stid.sc_client;
+	if (nfs4_check_and_expire_courtesy_client(clp))
+		return true;
+
 	if (!i_am_nfsd())
 		return false;
 	rqst = kthread_data(current);
-- 
2.9.5