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From:   "Benjamin Coddington" <bcodding@redhat.com>
To:     ZhangXiaoxu <zhangxiaoxu5@huawei.com>
Cc:     trond.myklebust@hammerspace.com, anna.schumaker@netapp.com,
        linux-nfs@vger.kernel.org
Subject: Re: [PATCH] NFS4: Fix v4.0 client state corruption when mount
Date:   Wed, 06 Nov 2019 11:47:02 -0500
Message-ID: <21D6F3D9-C1B6-4F5C-98A0-87B067C6E198@redhat.com>
In-Reply-To: <1557115023-86769-1-git-send-email-zhangxiaoxu5@huawei.com>
References: <1557115023-86769-1-git-send-email-zhangxiaoxu5@huawei.com>
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Hi ZhangXiaoxu,

I'm having a bit of trouble with this fix (which went upstream in
f02f3755dbd14fb935d24b14650fff9ba92243b8).

Since this change, my client calls SETCLIENTID/SETCLIENTID_CONFIRM twice=20
in
quick succession on mount, and the second SETCLIENTID_CONFIRM sent by=20
the state
manager can sometimes have the same verifier sent back by the first
SETCLIENTID's response.  I think we're missing a memory barrier=20
somewhere..

But, I do not understand how the client was able to corrupt the state=20
before
this patch, and I don't understand how the patch fixes state corruption.

Can anyone enlighten me as to how we were corrupting state here?

Ben

On 5 May 2019, at 23:57, ZhangXiaoxu wrote:

> stat command with soft mount never return after server is stopped.
>
> When alloc a new client, the state of the client will be set to
> NFS4CLNT_LEASE_EXPIRED.
>
> When the server is stopped, the state manager will work, and accord
> the state to recover. But the state is NFS4CLNT_LEASE_EXPIRED, it
> will drain the slot table and lead other task to wait queue, until
> the client recovered. Then the stat command is hung.
>
> When discover server trunking, the client will renew the lease,
> but check the client state, it lead the client state corruption.
>
> So, we need to call state manager to recover it when detect server
> ip trunking.
>
> Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com>
> ---
>  fs/nfs/nfs4state.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
> index 3de3647..f502f1c 100644
> --- a/fs/nfs/nfs4state.c
> +++ b/fs/nfs/nfs4state.c
> @@ -159,6 +159,10 @@ int nfs40_discover_server_trunking(struct=20
> nfs_client *clp,
>  =09=09/* Sustain the lease, even if it's empty.  If the clientid4
>  =09=09 * goes stale it's of no use for trunking discovery. */
>  =09=09nfs4_schedule_state_renewal(*result);
> +
> +=09=09/* If the client state need to recover, do it. */
> +=09=09if (clp->cl_state)
> +=09=09=09nfs4_schedule_state_manager(clp);
>  =09}
>  out:
>  =09return status;
> --=20
> 2.7.4