Re: [PATCH 0/9] mkfs.xfs: add mkfs.xfs.conf support

[Dave Chinner <david@fromorbit.com>]

On Fri, Mar 03, 2017 at 09:49:58PM -0600, Eric Sandeen wrote:
> On 3/3/17 5:13 PM, Luis R. Rodriguez wrote:
> > This series adds mkfs.xfs.conf support, so that options can now be
> > shoved into a configuration file. This enables certain defaults to be
> > saved for folks sticking to certain values, but more importantly it
> > also enables distributions to override certain defaults so that new
> > filesystems remain compatible with older distributions.
> > 
> > This has been based on top of xfsprogs-dev v4.9.0-rc1.
> > 
> > Given we already have an existinsg infrastructure to validate argument
> > values this reuses that infrastructure by first adding helpers and porting
> > over the argument parsing suppor to use these helpers.
> 
> I'm not necessarily the final word on this, but I have to say
> I'm not a huge fan of having mkfs config files.  I've lived 
> through that in mke2fs land, and my personal feeling is that
> it can lead to confusion when distros start shipping config
> files with different defaults than upstream ships in the
> code itself.
> 
> I guess I can see the argument for shipping old/compatible
> defaults with newer progs and older kernels, but by the
> time a distro ships a custom old default config file they could
> also patch out the new features just as easily... (which
> is also confusing, I guess ;) )
> 
> After 25+ years of no external config file, I'm concerned
> about principal of least surprise when the same xfsprogs version
> starts behaving differently on different boxes based on a new
> file that popped up in /etc ...
> 
> At the very least, I would like to /not/ ship or install any
> config file with xfsprogs by default; the code itself should
> be the canonical, single point of truth for defaults for a stock
> "make && make install" installation.

Hence my suggestion of libconfig - it can /write config files/ based
on the current mkfs config. So there's no need to ship default
config files - if a user wants a special config they can use mkfs to
generate it and they can install it appropriately.

e.g. 'mkfs -W <options>' outputs a config file to stdout that
matches the config specified on the command line, but does not make
the filesystem (similar to the "-n" option). If no options are
specified, the default config is emitted....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com