When v3 NLM request finds a conflicting delegation, it triggers
a delegation recall and nfsd_open fails with EAGAIN. nfsd_open
then translates EAGAIN into nfserr_jukebox. In nlm_fopen, instead
of returning nlm_failed for when there is a conflicting delegation,
drop this NLM request so that the client retries. Once delegation
is recalled and if a local lock is claimed, a retry would lead to
nfsd returning a nlm_lck_blocked error or a successful nlm lock.
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Olga Kornievskaia <okorniev@xxxxxxxxxx>
---
fs/nfsd/lockd.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/fs/nfsd/lockd.c b/fs/nfsd/lockd.c
index edc9f75dc75c..8fdc769d392e 100644
--- a/fs/nfsd/lockd.c
+++ b/fs/nfsd/lockd.c
@@ -57,6 +57,20 @@ nlm_fopen(struct svc_rqst *rqstp, struct nfs_fh *f, struct file **filp,
switch (nfserr) {
case nfs_ok:
return 0;
+ case nfserr_jukebox:
+ /* this error can indicate a presence of a conflicting
+ * delegation to an NLM lock request. Options are:
+ * (1) For now, drop this request and make the client
+ * retry. When delegation is returned, client's retry will
+ * complete.
+ * (2) NLM4_DENIED as per "spec" signals to the client
+ * that the lock is unavaiable now but client can retry.
+ * Linux client implementation does not. It treats
+ * NLM4_DENIED same as NLM4_FAILED and errors the request.
+ * (3) For the future, treat this as blocked lock and try
+ * to callback when the delegation is returned but might
+ * not have a proper lock request to block on.
+ */
case nfserr_dropit:
return nlm_drop_reply;
case nfserr_stale:
--
2.47.1
