linux-kernel - Re: [PATCH 2/5] ceph: stop using current_kernel

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Date:   Thu, 21 Jun 2018 20:29:28 +0800
From:   "Yan, Zheng" <ukernel@...il.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Zheng Yan <zyan@...hat.com>, Sage Weil <sage@...hat.com>,
        Ilya Dryomov <idryomov@...il.com>,
        y2038 Mailman List <y2038@...ts.linaro.org>,
        ceph-devel <ceph-devel@...r.kernel.org>,
        Jeff Layton <jlayton@...hat.com>,
        Chengguang Xu <cgxu519@....com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/5] ceph: stop using current_kernel_time()

On Wed, Jun 20, 2018 at 11:52 PM Arnd Bergmann <arnd@...db.de> wrote:
>
> ceph_mdsc_create_request() is one of the last callers of the
> deprecated current_kernel_time() as well as timespec_trunc().
>
> This changes it to use the timespec64 based interfaces instead,
> though we still need to convert the result until we are ready to
> change over req->r_stamp.
>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  fs/ceph/mds_client.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index dc8bc664a871..69c839316a7a 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -1779,6 +1779,7 @@ struct ceph_mds_request *
>  ceph_mdsc_create_request(struct ceph_mds_client *mdsc, int op, int mode)
>  {
>         struct ceph_mds_request *req = kzalloc(sizeof(*req), GFP_NOFS);
> +       struct timespec64 ts;
>
>         if (!req)
>                 return ERR_PTR(-ENOMEM);
> @@ -1797,7 +1798,9 @@ ceph_mdsc_create_request(struct ceph_mds_client *mdsc, int op, int mode)
>         init_completion(&req->r_safe_completion);
>         INIT_LIST_HEAD(&req->r_unsafe_item);
>
> -       req->r_stamp = timespec_trunc(current_kernel_time(), mdsc->fsc->sb->s_time_gran);
> +       ktime_get_coarse_real_ts64(&ts);
> +       req->r_stamp = timespec64_to_timespec(timespec64_trunc(ts,
> +                                               mdsc->fsc->sb->s_time_gran));
>

does current_time() internally uses ktime_get_coarse_real_ts64()?  If
not,  granularity difference may cause problem. see commit
56199016e8672feb7b903eda003a863d5bf2b8c4 for more information

Regards
Yan, Zheng

>         req->r_op = op;
>         req->r_direct_mode = mode;
> --
> 2.9.0
>
> --
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