[PATCH 2/8] nfsd: fix CB_SEQUENCE error handling of NFS4ERR_{BADSLOT,BADSESSION,SEQ_MISORDERED}

Jeff Layton
2025-01-23T20:25:38Z

The current error handling has some problems:

BADSLOT and BADSESSION: don't release the slot before retrying the call

SEQ_MISORDERED: does some sketchy resetting of the seqid? I can't find any
recommendation about doing that in the spec, and it seems wrong.

Handle all three errors the same way: release the slot, but then handle
it just like we would as if we hadn't gotten a reply; mark the session
as faulty, and retry the call.

Fixes: 7ba6cad6c88f ("nfsd: New helper nfsd4_cb_sequence_done() for processing more cb errors")
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
fs/nfsd/nfs4callback.c | 27 +++++++++++----------------
1 file changed, 11 insertions(+), 16 deletions(-)

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index e12205ef16ca932ffbcc86d67b0817aec2436c89..bfc9de1fcb67b4f05ed2f7a28038cd8290809c17 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -1371,17 +1371,24 @@ static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback
nfsd4_mark_cb_fault(cb->cb_clp);
ret = false;
break;
+ case -NFS4ERR_BADSESSION:
+ case -NFS4ERR_BADSLOT:
+ case -NFS4ERR_SEQ_MISORDERED:
+ /*
+ * These errors indicate that something has gone wrong
+ * with the server and client's synchronization. Release
+ * the slot, but handle it as if we hadn't gotten a reply.
+ */
+ nfsd41_cb_release_slot(cb);
+ fallthrough;
case 1:
/*
* cb_seq_status remains 1 if an RPC Reply was never
* received. NFSD can't know if the client processed
* the CB_SEQUENCE operation. Ask the client to send a
- * DESTROY_SESSION to recover.
+ * DESTROY_SESSION to recover, but keep the slot.
*/
- fallthrough;
- case -NFS4ERR_BADSESSION:
nfsd4_mark_cb_fault(cb->cb_clp);
- ret = false;
goto need_restart;
case -NFS4ERR_DELAY:
cb->cb_seq_status = 1;
@@ -1390,14 +1397,6 @@ static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback

rpc_delay(task, 2 * HZ);
return false;
- case -NFS4ERR_BADSLOT:
- goto retry_nowait;
- case -NFS4ERR_SEQ_MISORDERED:
- if (session->se_cb_seq_nr[cb->cb_held_slot] != 1) {
- session->se_cb_seq_nr[cb->cb_held_slot] = 1;
- goto retry_nowait;
- }
- break;
default:
nfsd4_mark_cb_fault(cb->cb_clp);
}
@@ -1405,10 +1404,6 @@ static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback
nfsd41_cb_release_slot(cb);
out:
return ret;
-retry_nowait:
- if (rpc_restart_call_prepare(task))
- ret = false;
- goto out;
need_restart:
if (!test_bit(NFSD4_CLIENT_CB_KILL, &clp->cl_flags)) {
trace_nfsd_cb_restart(clp, cb);

--
2.48.1