From: Zach Brown <zab-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Sage Weil <sage-BnTBU8nroG7k1uMJSBkQmQ@public.gmane.org>
Cc: Dave Chinner <david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org>,
Alexander Viro
<viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH RFC] vfs: add a O_NOMTIME flag
Date: Fri, 8 May 2015 10:11:15 -0700 [thread overview]
Message-ID: <20150508171115.GA13050@lenny.home.zabbo.net> (raw)
In-Reply-To: <alpine.DEB.2.00.1505071752520.28239-vIokxiIdD2AQNTJnQDzGJqxOck334EZe@public.gmane.org>
On Thu, May 07, 2015 at 06:01:23PM -0700, Sage Weil wrote:
> On Thu, 7 May 2015, Zach Brown wrote:
> > On Thu, May 07, 2015 at 10:26:17AM +1000, Dave Chinner wrote:
> > > On Wed, May 06, 2015 at 03:00:12PM -0700, Zach Brown wrote:
> > > > The criteria for using O_NOMTIME is the same as for using O_NOATIME:
> > > > owning the file or having the CAP_FOWNER capability. If we're not
> > > > comfortable allowing owners to prevent mtime/ctime updates then we
> > > > should add a tunable to allow O_NOMTIME. Maybe a mount option?
> > >
> > > I dislike "turn off safety for performance" options because Joe
> > > SpeedRacer will always select performance over safety.
> >
> > Well, for ceph there's no safety concern. They never use cmtime in
> > these files.
> >
> > So are you suggesting not implementing this and making them rework their
> > IO paths to avoid the fs maintaining mtime so that we don't give Joe
> > Speedracer more rope? Or are we talking about adding some speed bumps
> > that ceph can flip on that might give Joe Speedracer pause?
>
> I think this is the fundamental question: who do we give the ammunition
> to, the user or app writer, or the sysadmin?
Yeah, I think this is right. Dave doesn't want the possibility of it
bleeding in to installations through irresponsible default use in apps
without explicit buy-in from the people responsible for the backups.
> [...]
>
> Or, we can be conservative and require a mount option so that the admin
> has to explicitly allow behavior that might break some existing
> assumptions about mtime/ctime ('-o user_noatime' I guess?).
>
> I'm happy either way, so long as in the end an unprivileged ceph daemon
> avoids the useless work. In our case we always own the entire mount/disk,
> so a mount option is just fine.
It seems that the thread has headed towards responding to my suggestion
of a possible mount option with an enthusiastic "yes, please, no
surprises."
So I'll try that.
- z
next prev parent reply other threads:[~2015-05-08 17:11 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-06 22:00 [PATCH RFC] vfs: add a O_NOMTIME flag Zach Brown
2015-05-06 22:14 ` Trond Myklebust
2015-05-06 22:19 ` Sage Weil
[not found] ` <alpine.DEB.2.00.1505061515550.28239-vIokxiIdD2AQNTJnQDzGJqxOck334EZe@public.gmane.org>
2015-05-06 22:41 ` Zach Brown
[not found] ` <20150506224113.GA17282-fypN+1c5dIyjpB87vu3CluTW4wlIGRCZ@public.gmane.org>
2015-05-06 22:46 ` Sage Weil
2015-05-06 23:21 ` Theodore Ts'o
[not found] ` <1430949612-21356-1-git-send-email-zab-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2015-05-07 0:26 ` Dave Chinner
2015-05-07 17:20 ` Zach Brown
2015-05-07 18:43 ` Zach Brown
2015-05-08 1:01 ` Sage Weil
[not found] ` <alpine.DEB.2.00.1505071752520.28239-vIokxiIdD2AQNTJnQDzGJqxOck334EZe@public.gmane.org>
2015-05-08 1:23 ` Trond Myklebust
2015-05-08 15:19 ` Sage Weil
[not found] ` <CAHQdGtQjMHA8rVPkggB2zMz=k3O667+APH_1EY_2FtYmHL7-hw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-05-08 22:13 ` Dave Chinner
2015-05-08 22:24 ` Sage Weil
[not found] ` <alpine.DEB.2.00.1505081517470.28239-vIokxiIdD2AQNTJnQDzGJqxOck334EZe@public.gmane.org>
2015-05-10 23:13 ` Trond Myklebust
[not found] ` <CAHQdGtTFTN2XuvmarFZ9HPQV=cuhh7FosdHSrJME_U4htr=i8w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-05-11 7:31 ` Dave Chinner
2015-05-11 16:39 ` Sage Weil
2015-05-11 17:12 ` Trond Myklebust
[not found] ` <CAHQdGtT3rCf-ycAYw-=7HGaemg1+HfY8sw3+kb54VHONxDyP3w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-05-11 17:30 ` Sage Weil
2015-05-12 1:21 ` Dave Chinner
2015-05-12 23:12 ` Sage Weil
2015-05-13 0:57 ` Dave Chinner
[not found] ` <alpine.DEB.2.00.1505111020120.28239-vIokxiIdD2AQNTJnQDzGJqxOck334EZe@public.gmane.org>
2015-05-12 13:41 ` John Stoffel
2015-05-11 14:47 ` Theodore Ts'o
[not found] ` <20150511144719.GA14088-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2015-05-11 16:24 ` Sage Weil
[not found] ` <alpine.DEB.2.00.1505110920520.28239-vIokxiIdD2AQNTJnQDzGJqxOck334EZe@public.gmane.org>
2015-05-11 23:10 ` Theodore Ts'o
2015-05-12 5:08 ` Kevin Easton
[not found] ` <20150512050821.GA9404-Qr0l8DEfScZEV+tojptmR0B+6BGkLq7r@public.gmane.org>
2015-05-12 11:45 ` Austin S Hemmelgarn
[not found] ` <5551E7EB.8040301-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-05-12 13:54 ` John Stoffel
2015-05-12 14:36 ` J. Bruce Fields
[not found] ` <20150512143637.GA6370-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org>
2015-05-12 14:53 ` Austin S Hemmelgarn
2015-05-12 21:51 ` Dave Chinner
2015-05-13 15:16 ` Austin S Hemmelgarn
2015-05-12 22:39 ` NeilBrown
[not found] ` <20150513083951.5eb63bc0-wvvUuzkyo1EYVZTmpyfIwg@public.gmane.org>
2015-07-14 13:13 ` Pavel Machek
2015-07-15 4:54 ` NeilBrown
2015-07-22 13:47 ` Pavel Machek
2015-05-12 21:35 ` Sage Weil
2015-05-13 12:32 ` Jan Kara
2015-05-08 14:43 ` Austin S Hemmelgarn
2015-05-08 17:11 ` Zach Brown [this message]
2015-05-08 14:29 ` John Stoffel
2015-07-14 11:50 ` Pavel Machek
[not found] ` <20150507172053.GA659-fypN+1c5dIyjpB87vu3CluTW4wlIGRCZ@public.gmane.org>
2015-05-07 19:09 ` Richard Weinberger
2015-05-07 19:53 ` Andy Lutomirski
[not found] ` <554BC4D8.9010507@nod.at>
2015-05-07 20:06 ` Andy Lutomirski
[not found] ` <CALCETrWNDMq0nK3ac-uZweV5BKK_yWTQHH5D0YkyEu7bcONo9g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-05-08 2:42 ` Dave Chinner
2015-07-14 11:44 ` Pavel Machek
2015-05-08 2:37 ` Dave Chinner
2015-05-08 3:24 ` Andy Lutomirski
[not found] ` <CALCETrUksu5ZB4QBfC8DMwYO2OFjfPW2eWsTweZGN_gybzcsmw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-05-08 14:44 ` Eric Sandeen
2015-05-11 20:36 ` J. Bruce Fields
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150508171115.GA13050@lenny.home.zabbo.net \
--to=zab-h+wxahxf7alqt0dzr+alfa@public.gmane.org \
--cc=david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org \
--cc=linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=sage-BnTBU8nroG7k1uMJSBkQmQ@public.gmane.org \
--cc=viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).