Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751933AbdFAKWy (ORCPT ); Thu, 1 Jun 2017 06:22:54 -0400 Received: from mail-oi0-f65.google.com ([209.85.218.65]:35755 "EHLO mail-oi0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751636AbdFAKWt (ORCPT ); Thu, 1 Jun 2017 06:22:49 -0400 MIME-Version: 1.0 In-Reply-To: References: <1491613030-11599-1-git-send-email-deepa.kernel@gmail.com> <1491613030-11599-5-git-send-email-deepa.kernel@gmail.com> From: Arnd Bergmann Date: Thu, 1 Jun 2017 12:22:47 +0200 X-Google-Sender-Auth: 0wLGLbtw491B8wJRTzuv9Gi-5Lc Message-ID: Subject: Re: [PATCH 04/12] fs: ceph: CURRENT_TIME with ktime_get_real_ts() To: "Yan, Zheng" Cc: Deepa Dinamani , Linux Kernel Mailing List , Andrew Morton , Thomas Gleixner , Al Viro , gregkh , "Dilger, Andreas" , "J. Bruce Fields" , Chris Mason , David Miller , David Sterba , Evgeniy Dushistov , Eric Paris , Jaegeuk Kim , Josef Bacik , Jeff Layton , John Stultz , James Simmons , Ingo Molnar , "Drokin, Oleg" , Paul Moore , Steven Rostedt , yuchao0@huawei.com, ceph-devel , devel@driverdev.osuosl.org, linux-audit@redhat.com, linux-btrfs , linux-cifs@vger.kernel.org, "Linux F2FS DEV, Mailing List" , Linux FS-devel Mailing List , linux-mtd , LSM List , Lustre Development List , Networking , samba-technical@lists.samba.org, y2038 Mailman List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2306 Lines: 55 On Thu, Jun 1, 2017 at 11:56 AM, Yan, Zheng wrote: > On Sat, Apr 8, 2017 at 8:57 AM, Deepa Dinamani wrote: >> 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. Hmm, the change was not supposed to have a user-visible effect, so something has gone wrong, but I don't immediately see how it relates to what you observe. ktime_get_real_ts() and current_time() use the same time base, there is no drift, but there is a difference in resolution, as the latter uses the time stamp of the last jiffies update, which may be up to one jiffy (10ms) behind the exact time we put in the request stamps here. Do you still see problems if you use current_kernel_time() instead of ktime_get_real_ts()? Arnd