Re: [PATCH 0/4] ceph: allow ceph_d_revalidate to handle some cases under LOOKUP_RCU

["Yan, Zheng" <zyan@redhat.com>]

> On Jul 6, 2016, at 00:27, Jeff Layton <jlayton@redhat.com> wrote:
> 
> The basic idea with this set is to allow the kernel client to allow the
> client to do more d_revalidate functionality under the rcu_read_lock.
> The idea is basically to do what we can there while not blocking, and
> then return -ECHILD for the rest.
> 
> The only really questionable bit is the part where we need to take the
> d_lock in ceph_d_release. I think it should be largely uncontended, but
> it's still less than ideal. Maybe there is some way to handle that
> locklessly?
> 
> Also, it would be nice to not have to drop out of rcuwalk mode in order
> to run the lease renewal. It seems like the kind of thing that would be
> ideal to queue to a workqueue, but I don't see a way to do that without
> introducing a potential deadlock.
> 
> My teuthology run with it passed all but one test, which seems to have
> been an unrelated problem (though I could be wrong there).
> 
> Jeff Layton (4):
>  ceph: remove ceph_mdsc_lease_release
>  ceph: clear d_fsinfo pointer under d_lock
>  ceph: allow dentry_lease_is_valid to work under RCU walk
>  ceph: handle LOOKUP_RCU in ceph_d_revalidate
> 
> fs/ceph/dir.c        | 67 +++++++++++++++++++++++++++++++++++-----------------
> fs/ceph/mds_client.c | 41 --------------------------------
> fs/ceph/mds_client.h |  4 ----
> 3 files changed, 45 insertions(+), 67 deletions(-)

Reviewed-by: Yan, Zheng <zyan@redhat.com>


> 
> -- 
> 2.5.5
>