From: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
To: <dedekind1@gmail.com>
Cc: Dave Chinner <david@fromorbit.com>,
Richard Weinberger <richard@nod.at>,
<linux-mtd@lists.infradead.org>, <adrian.hunter@intel.com>,
<linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH RESEND] ubifs: Introduce a mount option of force_atime.
Date: Thu, 25 Jun 2015 18:10:56 +0800 [thread overview]
Message-ID: <558BD3B0.8080209@cn.fujitsu.com> (raw)
In-Reply-To: <1435226918.9627.14.camel@sauron.fi.intel.com>
On 06/25/2015 06:08 PM, Artem Bityutskiy wrote:
>
>
> On Thu, 2015-06-25 at 17:55 +0800, Dongsheng Yang wrote:
>> On 06/24/2015 08:33 AM, Dave Chinner wrote:
>>> On Tue, Jun 23, 2015 at 01:44:00PM +0300, Artem Bityutskiy wrote:
>>>> On Tue, 2015-06-23 at 17:55 +0800, Dongsheng Yang wrote:
>>>>> In short, I think force_atime to ubifs is the choice from my opinion.
>>>>
>>>> So will we end up with this:
>>>>
>>>> -o - no atime support
>>>> -o atime - no atime support
>>>> -o noatime - same, no atime support
>>>> -o force_atime - full atime support
>>>> -o relatime - relative atime support
>>>> -o lazyatime - lazy atime support
>>>
>>>> IOW, atime/noatime mount options have no effect on UBIFS. To have full
>>>> atime support - people have to use "force_atime". And then the rest of
>>>> the standard options are supported.
>>>
>>> That's the exact semantics of the standard -o strictatime option.
>>> See the mount(8) man page:
>>>
>>> strictatime
>>> Allows to explicitly requesting full atime updates.
>>> This makes it possible for kernel to defaults to
>>> relatime or noatime but still allow userspace to
>>> override it. For more details about the default system
>>> mount options see /proc/mounts.
>>>
>>> It's passed down to the kernel via the MS_STRICTATIME flag. All
>>> you need to do is make ubifs aware of this flag...
>>
>> Hi Dave, thanx for your suggestiong, but sorry, it's a little confusing
>> to me :(.
>
> I do not know the history, but IIUC, this is what Dave's hint translates
> to for UBIFS:
>
> -o - default behavior (no atime)
> -o atime - default behavior (no atime)
> -o noatime - default behavior (no atime)
>
> -o strictatime - full atime support
> -o relatime - relative atime support
> -o lazyatime - lazy atime support
>
> Is this logical from user's perspective? No, but this is a standard
> "hack", not an UBIFS-only "hack", so we are fine.
>
> "force_atime" that you are suggesting would be UBIFS-only hack, which is
> not as fine as a standard and documented "hack".
>
> IOW, atime/noatime are the "don't use" options, they are ignored and
> every file-system is free to use its own defaults, be that noatime or
> relatime or strictatime. If you want to tell the FS what to do, use
> strictatime/relatime/lazyatime.
Ha, okey, I believe there was some misunderstanding between us.
Yes, this is what we want:
> -o - default behavior (no atime)
> -o atime - default behavior (no atime)
> -o noatime - default behavior (no atime)
>
> -o strictatime - full atime support
> -o relatime - relative atime support
> -o lazyatime - lazy atime support
That's great!! But there is a problem to implement it.
Because we can not distinguish the cases below:
> -o - default behavior (no atime)
> -o relatime - relative atime support
We would find both of them are MS_RELATIME set. But we
want to do different thing in these cases. So I introduced
the force_atime. Then:
-o - no atime support
-o atime - no atime support
-o noatime - same, no atime support
-o force_atime - default behavior (relatime currently)
-o force_atime,relatime - relative atime support
-o force_atime,strictatime - strict atime support
-o force_atime,lazyatime - lazy atime support
But I agree that introducing a UBIFS_ATIME_SUPPORT as you suggested.
Yang
>
> Does it make sense?
>
> .
>
next prev parent reply other threads:[~2015-06-25 10:16 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-08 10:07 [PATCH RESEND] ubifs: Introduce a mount option of force_atime Dongsheng Yang
2015-06-08 22:35 ` Richard Weinberger
2015-06-08 22:55 ` Richard Weinberger
2015-06-09 2:57 ` Dongsheng Yang
2015-06-09 3:24 ` Dongsheng Yang
2015-06-09 5:00 ` Dongsheng Yang
2015-06-09 5:09 ` Dongsheng Yang
2015-06-09 6:36 ` Artem Bityutskiy
2015-06-09 8:02 ` Richard Weinberger
2015-06-10 3:16 ` Dongsheng Yang
2015-06-10 9:21 ` Artem Bityutskiy
2015-06-10 10:10 ` Dongsheng Yang
2015-06-10 10:25 ` Artem Bityutskiy
2015-06-10 10:34 ` Dongsheng Yang
2015-06-10 11:05 ` Artem Bityutskiy
2015-06-23 9:55 ` Dongsheng Yang
2015-06-23 10:44 ` Artem Bityutskiy
2015-06-23 23:49 ` Dongsheng Yang
2015-06-24 0:33 ` Dave Chinner
2015-06-24 16:04 ` Artem Bityutskiy
2015-06-25 9:55 ` Dongsheng Yang
2015-06-25 10:08 ` Artem Bityutskiy
2015-06-25 10:10 ` Dongsheng Yang [this message]
2015-06-25 11:28 ` Artem Bityutskiy
2015-06-26 1:17 ` Dongsheng Yang
2015-06-26 7:01 ` Artem Bityutskiy
2015-06-26 7:13 ` Dongsheng Yang
2015-06-26 7:43 ` Artem Bityutskiy
2015-06-26 7:52 ` Dongsheng Yang
2015-06-26 8:19 ` Artem Bityutskiy
2015-06-26 8:22 ` Dongsheng Yang
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=558BD3B0.8080209@cn.fujitsu.com \
--to=yangds.fnst@cn.fujitsu.com \
--cc=adrian.hunter@intel.com \
--cc=david@fromorbit.com \
--cc=dedekind1@gmail.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-mtd@lists.infradead.org \
--cc=richard@nod.at \
/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).