nfsd4: extend state lock over seqid replay logic

There are currently a couple races in the seqid replay code: a
retransmission could come while we're still encoding the original reply,
or a new seqid-mutating call could come as we're encoding a replay.

So, extend the state lock over the encoding (both encoding of a replayed
reply and caching of the original encoded reply).

I really hate doing this, and previously added the stateowner
reference-counting code to avoid it (which was insufficient)--but I
don't see a less complicated alternative at the moment.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 50bae7471147..50063a85f505 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -408,8 +408,8 @@ out:
 	if (open->op_stateowner) {
 		nfs4_get_stateowner(open->op_stateowner);
 		cstate->replay_owner = open->op_stateowner;
-	}
-	nfs4_unlock_state();
+	} else
+		nfs4_unlock_state();
 	return status;
 }
 
@@ -1227,6 +1227,7 @@ encode_op:
 			be32_to_cpu(status));
 
 		if (cstate->replay_owner) {
+			nfs4_unlock_state();
 			nfs4_put_stateowner(cstate->replay_owner);
 			cstate->replay_owner = NULL;
 		}