[systemd-devel] [RFC][PATCH] Add option to enable COW for journal file

[Goffredo Baroncelli]

On 2015-03-06 13:31, Lennart Poettering wrote:
> On Thu, 05.03.15 21:39, Goffredo Baroncelli (kreijack at libero.it) wrote:
> 
>>
>> Hi All,
>> the enclosed patches add an option to the journald.conf file to allow
>> a COW behavior for the journal files.
>>
[...]
> 
> I am pretty strongly against adding an explicit option for this. I
> consider this all a temporary stopgap, until btrfs's autodefrag makes
> the problem go away, and I am very conservative with adding new config
> options where it is already clear that they will eventually be
> useless.
> 
> What I'd be open to is:
> 
> a) beef up the tmpfiles logic to be able to do the equivalent of
>    /usr/bin/chattr on files. (By adding a new line type, make "h" or
>    so).
> 
> b) remove all code that sets NOCOW explicitly on journal files from
>    journald.
> 
> c) instead ship a tmpfiles snippet making use of a) that sets the
>    NOCOW flag for /var/lib/journal, which results in the flag being
>    inherited by journal files that are created within it.
> 
> If people then want to opt-out of NOCOW, they can simply override the
> tmpfiles snippet and all is good. That way we have a way to configure
> the bit, without actually introducing a high-level config option for
> this.

This seems reasonable; I will work on a proposal like this one.

> 
> Lennart
> 


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