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: Fri, 26 Jun 2015 15:52:24 +0800 [thread overview] Message-ID: <558D04B8.5050300@cn.fujitsu.com> (raw) In-Reply-To: <1435304624.9627.47.camel@sauron.fi.intel.com> On 06/26/2015 03:43 PM, Artem Bityutskiy wrote: > On Fri, 2015-06-26 at 15:13 +0800, Dongsheng Yang wrote: >> On 06/26/2015 03:01 PM, Artem Bityutskiy wrote: >>> On Fri, 2015-06-26 at 09:17 +0800, Dongsheng Yang wrote: >> ... >> >>> This means that if a file-system (e.g., UBIFS or JFFS2) never supported >>> atime, it is harder to add atime support without breaking the old >>> behavior. >>> >>> What if we push the two "set NOATIME flag" lines of code down to >>> individual file-systems, instead of having it at the VFS level? >> >> TO be sure I understand it correctly, do you mean pushing the flags >> parsing work to individual file-systems? Then we can set the default >> behavior in file-system itself. > > No, I mean removing these 2 lines from do_mount() > > /* Default to relatime */ > mnt_flags |= MNT_RELATIME; > > and add them to the > > struct file_system_type->mount() > > of every individual file-system (e.g., ext4_mount()). Well, it's possible, but I don't think others would like it. Because it create a lot of redundancy. If we want to make file_system_type to be aware of it, I prefer to introduce a file_system_type::parse_options() call back. Something like that: + if (type->parse_options) + type->parse_options(path, flags, mnt_flags); + else + generic_parse_options(path, flags, mnt_flags); > >> But there is another problem I called as problem 2 in my last mail. >> That we can not distinguish: >> -o - default behavior (*no atime*) >> -o atime - atime support > > -o atime does not mean anything from the kernel POW, it is only > user-space tools which may translate it to something meaningful for the > kernel. No file-systems can distinguish these two anyway. So I would say > this is not a problem, people have to use 'strictatime' instead. Yes, it's only used in util-linux now. But do you think it's weird that: -o atime - no atime (we treat it as the default behavior) -o noatime - no atime ? Yang > > What do you think about this as the alternative to the > UBIFS_ATIME_SUPPORT configuration switch, which will introduce > additional churn? > > . >
WARNING: multiple messages have this Message-ID (diff)
From: Dongsheng Yang <yangds.fnst@cn.fujitsu.com> To: <dedekind1@gmail.com> Cc: linux-fsdevel@vger.kernel.org, Richard Weinberger <richard@nod.at>, Dave Chinner <david@fromorbit.com>, adrian.hunter@intel.com, linux-mtd@lists.infradead.org Subject: Re: [PATCH RESEND] ubifs: Introduce a mount option of force_atime. Date: Fri, 26 Jun 2015 15:52:24 +0800 [thread overview] Message-ID: <558D04B8.5050300@cn.fujitsu.com> (raw) In-Reply-To: <1435304624.9627.47.camel@sauron.fi.intel.com> On 06/26/2015 03:43 PM, Artem Bityutskiy wrote: > On Fri, 2015-06-26 at 15:13 +0800, Dongsheng Yang wrote: >> On 06/26/2015 03:01 PM, Artem Bityutskiy wrote: >>> On Fri, 2015-06-26 at 09:17 +0800, Dongsheng Yang wrote: >> ... >> >>> This means that if a file-system (e.g., UBIFS or JFFS2) never supported >>> atime, it is harder to add atime support without breaking the old >>> behavior. >>> >>> What if we push the two "set NOATIME flag" lines of code down to >>> individual file-systems, instead of having it at the VFS level? >> >> TO be sure I understand it correctly, do you mean pushing the flags >> parsing work to individual file-systems? Then we can set the default >> behavior in file-system itself. > > No, I mean removing these 2 lines from do_mount() > > /* Default to relatime */ > mnt_flags |= MNT_RELATIME; > > and add them to the > > struct file_system_type->mount() > > of every individual file-system (e.g., ext4_mount()). Well, it's possible, but I don't think others would like it. Because it create a lot of redundancy. If we want to make file_system_type to be aware of it, I prefer to introduce a file_system_type::parse_options() call back. Something like that: + if (type->parse_options) + type->parse_options(path, flags, mnt_flags); + else + generic_parse_options(path, flags, mnt_flags); > >> But there is another problem I called as problem 2 in my last mail. >> That we can not distinguish: >> -o - default behavior (*no atime*) >> -o atime - atime support > > -o atime does not mean anything from the kernel POW, it is only > user-space tools which may translate it to something meaningful for the > kernel. No file-systems can distinguish these two anyway. So I would say > this is not a problem, people have to use 'strictatime' instead. Yes, it's only used in util-linux now. But do you think it's weird that: -o atime - no atime (we treat it as the default behavior) -o noatime - no atime ? Yang > > What do you think about this as the alternative to the > UBIFS_ATIME_SUPPORT configuration switch, which will introduce > additional churn? > > . >
next prev parent reply other threads:[~2015-06-26 7:57 UTC|newest] Thread overview: 60+ 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 10:07 ` 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 2:57 ` Dongsheng Yang 2015-06-09 3:24 ` Dongsheng Yang 2015-06-09 3:24 ` Dongsheng Yang 2015-06-09 5:00 ` Dongsheng Yang 2015-06-09 5:00 ` Dongsheng Yang 2015-06-09 5:09 ` Dongsheng Yang 2015-06-09 5:09 ` Dongsheng Yang 2015-06-09 6:36 ` Artem Bityutskiy 2015-06-09 6:36 ` Artem Bityutskiy 2015-06-09 8:02 ` Richard Weinberger 2015-06-09 8:02 ` Richard Weinberger 2015-06-10 3:16 ` Dongsheng Yang 2015-06-10 3:16 ` Dongsheng Yang 2015-06-10 9:21 ` Artem Bityutskiy 2015-06-10 9:21 ` Artem Bityutskiy 2015-06-10 10:10 ` Dongsheng Yang 2015-06-10 10:10 ` Dongsheng Yang 2015-06-10 10:25 ` Artem Bityutskiy 2015-06-10 10:25 ` Artem Bityutskiy 2015-06-10 10:34 ` Dongsheng Yang 2015-06-10 10:34 ` Dongsheng Yang 2015-06-10 11:05 ` Artem Bityutskiy 2015-06-10 11:05 ` Artem Bityutskiy 2015-06-23 9:55 ` Dongsheng Yang 2015-06-23 9:55 ` Dongsheng Yang 2015-06-23 10:44 ` Artem Bityutskiy 2015-06-23 10:44 ` Artem Bityutskiy 2015-06-23 23:49 ` Dongsheng Yang 2015-06-23 23:49 ` Dongsheng Yang 2015-06-24 0:33 ` Dave Chinner 2015-06-24 0:33 ` Dave Chinner 2015-06-24 16:04 ` Artem Bityutskiy 2015-06-24 16:04 ` Artem Bityutskiy 2015-06-25 9:55 ` Dongsheng Yang 2015-06-25 9:55 ` Dongsheng Yang 2015-06-25 10:08 ` Artem Bityutskiy 2015-06-25 10:08 ` Artem Bityutskiy 2015-06-25 10:10 ` Dongsheng Yang 2015-06-25 10:10 ` Dongsheng Yang 2015-06-25 11:28 ` Artem Bityutskiy 2015-06-25 11:28 ` Artem Bityutskiy 2015-06-26 1:17 ` Dongsheng Yang 2015-06-26 1:17 ` Dongsheng Yang 2015-06-26 7:01 ` Artem Bityutskiy 2015-06-26 7:01 ` Artem Bityutskiy 2015-06-26 7:13 ` Dongsheng Yang 2015-06-26 7:13 ` Dongsheng Yang 2015-06-26 7:43 ` Artem Bityutskiy 2015-06-26 7:43 ` Artem Bityutskiy 2015-06-26 7:52 ` Dongsheng Yang [this message] 2015-06-26 7:52 ` Dongsheng Yang 2015-06-26 8:19 ` Artem Bityutskiy 2015-06-26 8:19 ` Artem Bityutskiy 2015-06-26 8:22 ` Dongsheng Yang 2015-06-26 8:22 ` Dongsheng Yang
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