[PATCH RFC v15 03/11] NFSD: Add lm_lock_expired call out

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

Add callout function nfsd4_lm_lock_expired for lm_lock_expired.
If lock request has conflict with courtesy client then expire the
courtesy client and return no conflict to caller.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index a65d59510681..583ac807e98d 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -6578,10 +6578,47 @@ nfsd4_lm_notify(struct file_lock *fl)
 	}
 }
 
+/**
+ * nfsd4_lm_lock_expired - check if lock conflict can be resolved.
+ *
+ * @fl: pointer to file_lock with a potential conflict
+ * Return values:
+ *   %false: real conflict, lock conflict can not be resolved.
+ *   %true: no conflict, lock conflict was resolved.
+ *
+ * Note that this function is called while the flc_lock is held.
+ */
+static bool
+nfsd4_lm_lock_expired(struct file_lock *fl)
+{
+	struct nfs4_lockowner *lo;
+	struct nfs4_client *clp;
+	bool rc = false;
+
+	if (!fl)
+		return false;
+	lo = (struct nfs4_lockowner *)fl->fl_owner;
+	clp = lo->lo_owner.so_client;
+
+	/* need to sync with courtesy client trying to reconnect */
+	spin_lock(&clp->cl_cs_lock);
+	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
+		rc = true;
+	else {
+		if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
+			set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
+			rc =  true;
+		}
+	}
+	spin_unlock(&clp->cl_cs_lock);
+	return rc;
+}
+
 static const struct lock_manager_operations nfsd_posix_mng_ops  = {
 	.lm_notify = nfsd4_lm_notify,
 	.lm_get_owner = nfsd4_lm_get_owner,
 	.lm_put_owner = nfsd4_lm_put_owner,
+	.lm_lock_expired = nfsd4_lm_lock_expired,
 };
 
 static inline void
-- 
2.9.5