Re: [RFC PATCH 0/4] ceph: fix spurious recover_session=clean errors

["Yan, Zheng" <ukernel@gmail.com>]

On Fri, Sep 25, 2020 at 10:08 PM Jeff Layton <jlayton@kernel.org> wrote:
>
> Ilya noticed that he would get spurious EACCES errors on calls done just
> after blocklisting the client on mounts with recover_session=clean. The
> session would get marked as REJECTED and that caused in-flight calls to
> die with EACCES. This patchset seems to smooth over the problem, but I'm
> not fully convinced it's the right approach.
>

the root is cause is that client does not recover session instantly
after getting rejected by mds. Before session gets recovered, client
continues to return error.


> The potential issue I see is that the client could take cap references to
> do a call on a session that has been blocklisted. We then queue the
> message and reestablish the session, but we may not have been granted
> the same caps by the MDS at that point.
>
> If this is a problem, then we probably need to rework it so that we
> return a distinct error code in this situation and have the upper layers
> issue a completely new mds request (with new cap refs, etc.)
>
> Obviously, that's a much more invasive approach though, so it would be
> nice to avoid that if this would suffice.
>
> Jeff Layton (4):
>   ceph: don't WARN when removing caps due to blocklisting
>   ceph: don't mark mount as SHUTDOWN when recovering session
>   ceph: remove timeout on allowing reconnect after blocklisting
>   ceph: queue request when CLEANRECOVER is set
>
>  fs/ceph/caps.c       |  2 +-
>  fs/ceph/mds_client.c | 10 ++++------
>  fs/ceph/super.c      | 13 +++++++++----
>  fs/ceph/super.h      |  1 -
>  4 files changed, 14 insertions(+), 12 deletions(-)
>
> --
> 2.26.2
>