I've been cooking a very simple patch that hopefully gives both sides
of the "great strictatime war" what they want with minimal pain. I
sent it through kernelnewbies for a basic review and got some polish on
irc.
----
Signed-off-by: Raymond Jennings <shentino@xxxxxxxxx>
Reviewed-by: Mandeep Sandhu <mandeepsandhu.chd@xxxxxxxxx>
diff --git a/fs/Kconfig b/fs/Kconfig
index 6ce72d8..122a993 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -4,6 +4,20 @@
menu "File systems"
+config DEFAULT_STRICTATIME
+ bool "Use strictatime by default"
+ default n
+ help
+ Use strictatime as a default mount option.
+
+ Relatime became the default in 2007 to reduce I/O load on block
devices.
+
+ Enabling this option will restore historic behavior and provide
perfectly
+ accurate atimes, but the increase in write load may reduce
performance
+ and shorten the life of the block device.
+
+ If unsure, say N.
+
# Use unaligned word dcache accesses
config DCACHE_WORD_ACCESS
bool
diff --git a/fs/namespace.c b/fs/namespace.c
index 0570729..48e7c15 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2680,9 +2680,15 @@ long do_mount(const char *dev_name, const char
__user *dir_name,
if (retval)
goto dput_out;
- /* Default to relatime unless overriden */
+#ifdef CONFIG_DEFAULT_STRICTATIME
+ /* Default to strictatime unless overridden */
+ if (flags & MS_RELATIME)
+ mnt_flags |= MNT_RELATIME;
+#else
+ /* Default to relatime unless overridden */
if (!(flags & MS_NOATIME))
mnt_flags |= MNT_RELATIME;
+#endif
/* Separate the per-mountpoint flags */
if (flags & MS_NOSUID)
---------- Forwarded message ----------
From: Mandeep Sandhu <mandeepsandhu.chd@xxxxxxxxx>
Subject: Re: [PATCH] allow strictatime to be set as a global default
Date: Sat, 19 Dec 2015 17:25:37 -0800
To: Raymond Jennings <shentino@xxxxxxxxx>
Cc: kernelnewbies <kernelnewbies@xxxxxxxxxxxxxxxxx>
Looks good to me.
To test the real waters....you should send it to the lists you
mentioned (or whatever the maintainers script tells you).
Good luck,
-mandeep
On Sat, Dec 19, 2015 at 1:41 PM, Raymond Jennings <shentino@xxxxxxxxx>
wrote:
> How does this version look?
>
> (the other delta for the other file was untouched)
>
> Any chance it is ready to post to the big list (presumably fs with a
> cc to
> lkml)?
>
> diff --git a/fs/Kconfig b/fs/Kconfig
> index 6ce72d8..122a993 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -4,6 +4,20 @@
>
> menu "File systems"
>
> +config DEFAULT_STRICTATIME
> + bool "Use strictatime by default"
> + default n
> + help
> + Use strictatime as a default mount option.
> +
> + Relatime became the default in 2007 to reduce I/O load on block
> devices.
> +
> + Enabling this option will restore historic behavior and provide
> perfectly
> + accurate atimes, but the increase in write load may reduce
> performance
> + and shorten the life of the block device.
> +
> + If unsure, say N.
> +
> # Use unaligned word dcache accesses
> config DCACHE_WORD_ACCESS
> bool
>
> On Fri, Dec 18, 2015 at 2:21 PM, Mandeep Sandhu
> <mandeepsandhu.chd@xxxxxxxxx> wrote:
>>
>> Ah yes...now it makes sense! :)
>>
>> The current 'word of caution' (about increased I/O load on block
>> devices), seems mild IMHO. Maybe we should we have a stricter
>> warning...something like enabling this option might be harmful to
>> the
>> life of your block device (due to excessive writes) and will also
>> lead
>> to reduced performance?
>>
>> HTH,
>> -mandeep
>>
>>
>> On Fri, Dec 18, 2015 at 2:12 PM, Raymond Jennings
>> <shentino@xxxxxxxxx>
>> wrote:
>> > On Fri, Dec 18, 2015 at 10:50 AM, Mandeep Sandhu
>> > <mandeepsandhu.chd@xxxxxxxxx> wrote:
>> >>
>> >> You've removed the strictatime option altogether. So how does
>> that
>> >> satisfy people who _do_ want it?
>> >
>> >
>> > ...actually it looks like I was an idiot and got my diff
>> backwards when
>> > I
>> > pulled it out of git :P
>> >
>> > Here's the correct version.
>> >
>> > diff --git a/fs/Kconfig b/fs/Kconfig
>> > index 6ce72d8..4b917eb 100644
>> > --- a/fs/Kconfig
>> > +++ b/fs/Kconfig
>> > @@ -4,6 +4,17 @@
>> >
>> > menu "File systems"
>> >
>> > +config DEFAULT_STRICTATIME
>> > + bool "Use strictatime by default"
>> > + default n
>> > + help
>> > + Use strictatime as a default mount option.
>> > +
>> > + Strictatime preserves ancient historic behavior of
>> keeping the
>> > atime field always up to date.
>> > + However, it was changed in 2007 to relatime to reduce
>> I/O load
>> > on
>> > block devices.
>> > +
>> > + If unsure, say N.
>> > +
>> > # Use unaligned word dcache accesses
>> > config DCACHE_WORD_ACCESS
>> > bool
>> > diff --git a/fs/namespace.c b/fs/namespace.c
>> > index 0570729..48e7c15 100644
>> > --- a/fs/namespace.c
>> > +++ b/fs/namespace.c
>> > @@ -2680,9 +2680,15 @@ long do_mount(const char *dev_name, const
>> char
>> > __user
>> > *dir_name,
>> > if (retval)
>> > goto dput_out;
>> >
>> > - /* Default to relatime unless overriden */
>> > +#ifdef CONFIG_DEFAULT_STRICTATIME
>> > + /* Default to strictatime unless overridden */
>> > + if (flags & MS_RELATIME)
>> > + mnt_flags |= MNT_RELATIME;
>> > +#else
>> > + /* Default to relatime unless overridden */
>> > if (!(flags & MS_NOATIME))
>> > mnt_flags |= MNT_RELATIME;
>> > +#endif
>> >
>> >
>> > /* Separate the per-mountpoint flags */
>> > if (flags & MS_NOSUID)
>> >
>> >
>> >
>
>
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