Re: [PATCH 04/12] fs: ceph: CURRENT_TIME with ktime_get_real_ts()

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

On Sat, Apr 8, 2017 at 8:57 AM, Deepa Dinamani <deepa.kernel@gmail.com> wrote:
> CURRENT_TIME is not y2038 safe.
> The macro will be deleted and all the references to it
> will be replaced by ktime_get_* apis.
>
> struct timespec is also not y2038 safe.
> Retain timespec for timestamp representation here as ceph
> uses it internally everywhere.
> These references will be changed to use struct timespec64
> in a separate patch.
>
> The current_fs_time() api is being changed to use vfs
> struct inode* as an argument instead of struct super_block*.
>
> Set the new mds client request r_stamp field using
> ktime_get_real_ts() instead of using current_fs_time().
>
> Also, since r_stamp is used as mtime on the server, use
> timespec_trunc() to truncate the timestamp, using the right
> granularity from the superblock.
>
> This api will be transitioned to be y2038 safe along
> with vfs.
>
> Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
> Reviewed-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/block/rbd.c   | 2 +-
>  fs/ceph/mds_client.c  | 4 +++-
>  net/ceph/messenger.c  | 6 ++++--
>  net/ceph/osd_client.c | 4 ++--
>  4 files changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index 517838b..77204da 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -1922,7 +1922,7 @@ static void rbd_osd_req_format_write(struct rbd_obj_request *obj_request)
>  {
>         struct ceph_osd_request *osd_req = obj_request->osd_req;
>
> -       osd_req->r_mtime = CURRENT_TIME;
> +       ktime_get_real_ts(&osd_req->r_mtime);
>         osd_req->r_data_offset = obj_request->offset;
>  }
>
> diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> index c681762..1d3fa90 100644
> --- a/fs/ceph/mds_client.c
> +++ b/fs/ceph/mds_client.c
> @@ -1666,6 +1666,7 @@ 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 timespec ts;
>
>         if (!req)
>                 return ERR_PTR(-ENOMEM);
> @@ -1684,7 +1685,8 @@ 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 = current_fs_time(mdsc->fsc->sb);
> +       ktime_get_real_ts(&ts);
> +       req->r_stamp = timespec_trunc(ts, mdsc->fsc->sb->s_time_gran);

This change causes our kernel_untar_tar test case to fail (inode's
ctime goes back). The reason is that there is time drift between the
time stamps got by  ktime_get_real_ts() and current_time(). We need to
revert this change until current_time() uses ktime_get_real_ts()
internally.

Regards
Yan, Zheng


>
>         req->r_op = op;
>         req->r_direct_mode = mode;
> diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
> index f76bb33..5766a6c 100644
> --- a/net/ceph/messenger.c
> +++ b/net/ceph/messenger.c
> @@ -1386,8 +1386,9 @@ static void prepare_write_keepalive(struct ceph_connection *con)
>         dout("prepare_write_keepalive %p\n", con);
>         con_out_kvec_reset(con);
>         if (con->peer_features & CEPH_FEATURE_MSGR_KEEPALIVE2) {
> -               struct timespec now = CURRENT_TIME;
> +               struct timespec now;
>
> +               ktime_get_real_ts(&now);
>                 con_out_kvec_add(con, sizeof(tag_keepalive2), &tag_keepalive2);
>                 ceph_encode_timespec(&con->out_temp_keepalive2, &now);
>                 con_out_kvec_add(con, sizeof(con->out_temp_keepalive2),
> @@ -3176,8 +3177,9 @@ bool ceph_con_keepalive_expired(struct ceph_connection *con,
>  {
>         if (interval > 0 &&
>             (con->peer_features & CEPH_FEATURE_MSGR_KEEPALIVE2)) {
> -               struct timespec now = CURRENT_TIME;
> +               struct timespec now;
>                 struct timespec ts;
> +               ktime_get_real_ts(&now);
>                 jiffies_to_timespec(interval, &ts);
>                 ts = timespec_add(con->last_keepalive_ack, ts);
>                 return timespec_compare(&now, &ts) >= 0;
> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> index e15ea9e..242d7c0 100644
> --- a/net/ceph/osd_client.c
> +++ b/net/ceph/osd_client.c
> @@ -3574,7 +3574,7 @@ ceph_osdc_watch(struct ceph_osd_client *osdc,
>         ceph_oid_copy(&lreq->t.base_oid, oid);
>         ceph_oloc_copy(&lreq->t.base_oloc, oloc);
>         lreq->t.flags = CEPH_OSD_FLAG_WRITE;
> -       lreq->mtime = CURRENT_TIME;
> +       ktime_get_real_ts(&lreq->mtime);
>
>         lreq->reg_req = alloc_linger_request(lreq);
>         if (!lreq->reg_req) {
> @@ -3632,7 +3632,7 @@ int ceph_osdc_unwatch(struct ceph_osd_client *osdc,
>         ceph_oid_copy(&req->r_base_oid, &lreq->t.base_oid);
>         ceph_oloc_copy(&req->r_base_oloc, &lreq->t.base_oloc);
>         req->r_flags = CEPH_OSD_FLAG_WRITE;
> -       req->r_mtime = CURRENT_TIME;
> +       ktime_get_real_ts(&req->r_mtime);
>         osd_req_op_watch_init(req, 0, lreq->linger_id,
>                               CEPH_OSD_WATCH_OP_UNWATCH);
>
> --
> 2.7.4
>