Re: [PATCH 6.1.y] net: tls: handle backlogging of crypto requests

Trond Myklebust
2024-09-09T17:56:16Z

On Mon, 2024-09-09 at 16:36 +0000, Oleksandr Tymoshenko wrote:
> > > nfs41_init_clientid does not signal a failure condition from
> > > nfs4_proc_exchange_id and nfs4_proc_create_session to a client
> > > which
> > > may
> > > lead to mount syscall indefinitely blocked in the following stack
>
> > NACK. This will break all sorts of recovery scenarios, because it
> > doesn't distinguish between an initial 'mount' and a server reboot
> > recovery situation.
> > Even in the case where we are in the initial mount, it also doesn't
> > distinguish between transient errors such as NFS4ERR_DELAY or
> > reboot
> > errors such as NFS4ERR_STALE_CLIENTID, etc.
>
> > Exactly what is the scenario that is causing your hang? Let's try
> > to
> > address that with a more targeted fix.
>
> The scenario is as follows: there are several NFS servers and several
> production machines with multiple NFS mounts. This is a containerized
> multi-tennant workflow so every tennant gets its own NFS mount to
> access their
> data. At some point nfs41_init_clientid fails in the initial
> mount.nfs call
> and all subsequent mount.nfs calls just hang in
> nfs_wait_client_init_complete
> until the original one, where nfs4_proc_exchange_id has failed, is
> killed.
>
> The cause of the nfs41_init_clientid failure in the production case
> is a timeout.
> The following error message is observed in logs:
>   NFS: state manager: lease expired failed on NFSv4 server <ip> with
> error 110
>

How about something like the following fix then?
8<-----------------------------------------------
From eb402b489bb0d0ada1a3dd9101d4d7e193402e46 Mon Sep 17 00:00:00 2001
Message-ID: <eb402b489bb0d0ada1a3dd9101d4d7e193402e46.1725904471.git.trond.myklebust@hammerspace.com>
From: Trond Myklebust <trond.myklebust@hammerspace.com>
Date: Mon, 9 Sep 2024 13:47:07 -0400
Subject: [PATCH] NFSv4: Fail mounts if the lease setup times out

If the server is down when the client is trying to mount, so that the
calls to exchange_id or create_session fail, then we should allow the
mount system call to fail rather than hang and block other mount/umount
calls.

Reported-by: Oleksandr Tymoshenko <ovt@google.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
fs/nfs/nfs4state.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 30aba1dedaba..59dcdf9bc7b4 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -2024,6 +2024,12 @@ static int nfs4_handle_reclaim_lease_error(struct nfs_client *clp, int status)
nfs_mark_client_ready(clp, -EPERM);
clear_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
return -EPERM;
+ case -ETIMEDOUT:
+ if (clp->cl_cons_state == NFS_CS_SESSION_INITING) {
+ nfs_mark_client_ready(clp, -EIO);
+ return -EIO;
+ }
+ fallthrough;
case -EACCES:
case -NFS4ERR_DELAY:
case -EAGAIN:
--
2.46.0

--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com