On Thu, May 24, 2012 at 03:42:17PM -0400, Weston Andros Adamson wrote:
> Initiate a CB probe when a new connection with the correct direction is added
> to a session (IFF backchannel is marked as down). Without this a
> BIND_CONN_TO_SESSION has no effect on the internal backchannel state, which
> causes the server to reply to every SEQUENCE op with the
> SEQ4_STATUS_CB_PATH_DOWN flag set until DESTROY_SESSION.
>
> Signed-off-by: Weston Andros Adamson <dros@xxxxxxxxxx>
> ---
> Hey Bruce -
> In an earlier thread I mentioned that I was setting the backchannel state to
> CB_UNKNOWN to clear the SEQ4_STATUS flag, but this was wrong - I don't believe
> it would ever change (to CB_UP/CB_DOWN). This patch seems like the right way
> to handle the internal backchannel state.
Thanks, yes, this looks right, queueing up for 3.6.
> Also, I'm a bit confused as how we're supposed to maintain atomicity around
> cl_cb_state:
>
> from nfs4callback.c:nfsd4_probe_callback():
> /* XXX: atomicity? Also, should we be using cl_flags? */
> clp->cl_cb_state = NFSD4_CB_UNKNOWN;
>
> and there are several places that check the value of cl_cb_state without holding
> a lock (as far as I can tell).
I think that's probably OK.
We set cl_cb_state to UNKNOWN only before initiating a callback that
will eventually result in setting it to UP, DOWN, or FAULT.
And I think that's good enough for the readers.
So probably that comment should just go.
--b.
>
> fs/nfsd/nfs4state.c | 5 +++++
> 1 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 9afc902..99f092e 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -862,6 +862,11 @@ static __be32 nfsd4_new_conn(struct svc_rqst *rqstp, struct nfsd4_session *ses,
> if (ret)
> /* oops; xprt is already down: */
> nfsd4_conn_lost(&conn->cn_xpt_user);
> + if (ses->se_client->cl_cb_state == NFSD4_CB_DOWN &&
> + dir & NFS4_CDFC4_BACK) {
> + /* callback channel may be back up */
> + nfsd4_probe_callback(ses->se_client);
> + }
> return nfs_ok;
> }
>
> --
> 1.7.4.4
>
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