Re: [MAINTAINERS/KERNEL SUMMIT] Trust and maintenance of file systems

[Bagas Sanjaya <bagasdotme@gmail.com>]

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On Thu, Sep 07, 2023 at 08:54:38AM +1000, Dave Chinner wrote:
> There's a bigger policy question around that.
> 
> I think that if we are going to have filesystems be "community
> maintained" because they have no explicit maintainer, we need some
> kind of standard policy to be applied.
> 
> I'd argue that the filesystem needs, at minimum, a working mkfs and
> fsck implementation, and that it is supported by fstests so anyone
> changing core infrastructure can simply run fstests against the
> filesystem to smoke test the infrastructure changes they are making.

OK.

> 
> I'd suggest that syzbot coverage of such filesystems is not desired,
> because nobody is going to be fixing problems related to on-disk
> format verification. All we really care about is that a user can
> read and write to the filesystem without trashing anything.
> 
> I'd also suggest that we mark filesystem support state via fstype
> flags rather than config options. That way we aren't reliant on
> distros setting config options correctly to include/indicate the
> state of the filesystem implementation. We could also use similar
> flags for indicating deprecation and obsolete state (i.e. pending
> removal) and have code in the high level mount path issue the
> relevant warnings.

Something like xfs v4 format?

> 
> This method of marking would also allow us to document and implement
> a formal policy for removal of unmaintained and/or obsolete
> filesystems without having to be dependent on distros juggling
> config variables to allow users to continue using deprecated, broken
> and/or obsolete filesystem implementations right up to the point
> where they are removed from the kernel.
> 
> And let's not forget: removing a filesystem from the kernel is not
> removing end user support for extracting data from old filesystems.
> We have VMs for that - we can run pretty much any kernel ever built
> inside a VM, so users that need to extract data from a really old
> filesystem we no longer support in a modern kernel can simply boot
> up an old distro that did support it and extract the data that way.
> 
> We need to get away from the idea that we have to support old
> filesystems forever because someone, somewhere might have an old
> disk on the shelf with that filesystem on it and they might plug it
> in one day. If that day ever happens, they can go to the effort of
> booting an era-relevant distro in a VM to extract that data. It
> makes no sense to put an ongoing burden on current development to
> support this sort of rare, niche use case....

This reminds me of me going to a random internet cafe when kids played
popular online games (think of Point Blank), with the computers were
running Windows XP which was almost (and already) EOL, yet these
games still supported it (kudos to game developers).

Thanks.

-- 
An old man doll... just what I always wanted! - Clara

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