From: Chuck Lever <[email protected]>
There are one or two cases where CREATE_SESSION returns
NFS4ERR_DELAY in order to force the client to wait a bit and try
CREATE_SESSION again. However, after commit e4469c6cc69b ("NFSD: Fix
the NFSv4.1 CREATE_SESSION operation"), NFSD caches that response in
the CREATE_SESSION slot. Thus, when the client resends the
CREATE_SESSION, the server always returns the cached NFS4ERR_DELAY
response rather than actually executing the request and properly
recording its outcome. This blocks the client from making further
progress.
RFC 8881 Section 15.1.1.3 says:
> If NFS4ERR_DELAY is returned on an operation other than SEQUENCE
> that validly appears as the first operation of a request ... [t]he
> request can be retried in full without modification. In this case
> as well, the replier MUST avoid returning a response containing
> NFS4ERR_DELAY as the response to an initial operation of a request
> solely on the basis of its presence in the reply cache.
Neither the original NFSD code nor the discussion in section 18.36.4
refer explicitly to this important requirement, so I missed it.
Note also that not only must the server not cache NFS4ERR_DELAY, but
it has to not advance the CREATE_SESSION slot sequence number so
that it can properly recognize and accept the client's retry.
Reported-by: Dai Ngo <[email protected]>
Fixes: e4469c6cc69b ("NFSD: Fix the NFSv4.1 CREATE_SESSION operation")
Tested-by: Dai Ngo <[email protected]>
Signed-off-by: Chuck Lever <[email protected]>
---
fs/nfsd/nfs4state.c | 36 +++++++++++++++++++++++++-----------
1 file changed, 25 insertions(+), 11 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index ee9aa4843443..5fcd93f7cb8c 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -3831,15 +3831,20 @@ nfsd4_create_session(struct svc_rqst *rqstp,
else
cs_slot = &unconf->cl_cs_slot;
status = check_slot_seqid(cr_ses->seqid, cs_slot->sl_seqid, 0);
- if (status) {
- if (status == nfserr_replay_cache) {
- status = nfsd4_replay_create_session(cr_ses, cs_slot);
- goto out_free_conn;
- }
+ switch (status) {
+ case nfs_ok:
+ cs_slot->sl_seqid++;
+ cr_ses->seqid = cs_slot->sl_seqid;
+ break;
+ case nfserr_replay_cache:
+ status = nfsd4_replay_create_session(cr_ses, cs_slot);
+ fallthrough;
+ case nfserr_jukebox:
+ /* The server MUST NOT cache NFS4ERR_DELAY */
+ goto out_free_conn;
+ default:
goto out_cache_error;
}
- cs_slot->sl_seqid++;
- cr_ses->seqid = cs_slot->sl_seqid;
/* RFC 8881 Section 18.36.4 Phase 3: Client ID confirmation. */
if (conf) {
@@ -3859,10 +3864,8 @@ nfsd4_create_session(struct svc_rqst *rqstp,
old = find_confirmed_client_by_name(&unconf->cl_name, nn);
if (old) {
status = mark_client_expired_locked(old);
- if (status) {
- old = NULL;
- goto out_cache_error;
- }
+ if (status)
+ goto out_expired_error;
trace_nfsd_clid_replaced(&old->cl_clientid);
}
move_to_confirmed(unconf);
@@ -3894,6 +3897,17 @@ nfsd4_create_session(struct svc_rqst *rqstp,
expire_client(old);
return status;
+out_expired_error:
+ old = NULL;
+ /*
+ * Revert the slot seq_nr change so the server will process
+ * the client's resend instead of returning a cached response.
+ */
+ if (status == nfserr_jukebox) {
+ cs_slot->sl_seqid--;
+ cr_ses->seqid = cs_slot->sl_seqid;
+ goto out_free_conn;
+ }
out_cache_error:
nfsd4_cache_create_session(cr_ses, cs_slot, status);
out_free_conn: