linux-kernel - Re: [PATCH] ceph: don't WARN if we're still opening a session to an MDS

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Date:   Thu, 15 Jul 2021 10:02:41 -0400
From:   Jeff Layton <jlayton@...nel.org>
To:     Luis Henriques <lhenriques@...e.de>,
        Ilya Dryomov <idryomov@...il.com>, Xiubo Li <xiubli@...hat.com>
Cc:     ceph-devel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ceph: don't WARN if we're still opening a session to an
 MDS

On Thu, 2021-07-15 at 14:40 +0100, Luis Henriques wrote:
> If MDSs aren't available while mounting a filesystem, the session state will
> transition from SESSION_OPENING to SESSION_CLOSING.  And in that scenario
> check_session_state() will be called from delayed_work() and trigger this
> WARN.
> 
> Avoid this by only WARNing after a session has already been established
> (i.e., the s_ttl will be different from 0).
> 
> Fixes: 62575e270f66 ("ceph: check session state after bumping session->s_seq")
> Signed-off-by: Luis Henriques <lhenriques@...e.de>
> ---
>  fs/ceph/mds_client.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index e5af591d3bd4..86f09b1110a2 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -4468,7 +4468,7 @@ bool check_session_state(struct ceph_mds_session *s)
>  		break;
>  	case CEPH_MDS_SESSION_CLOSING:
>  		/* Should never reach this when we're unmounting */
> -		WARN_ON_ONCE(true);
> +		WARN_ON_ONCE(s->s_ttl);
>  		fallthrough;
>  	case CEPH_MDS_SESSION_NEW:
>  	case CEPH_MDS_SESSION_RESTARTING:

Mea culpa -- I've been meaning to fix that up. I'll plan to merge this
later today.

Thanks!
-- 
Jeff Layton <jlayton@...nel.org>