Re: Which xfsprogs version to which kernel version

Martin Steigerwald
2015-12-01T08:30:08Z

Am Dienstag, 1. Dezember 2015, 08:41:04 CET schrieb Dave Chinner:
> On Thu, Nov 26, 2015 at 11:21:45AM +0100, aluno3@poczta.onet.pl wrote:
> > Hello,
> >
> > I am using kernel 3.10 and would like to update xfsprogs (currently I
> > have 3.1.5).
> >
> > When I tried to use the newest version of xfsprogs 4.3.0 I get the call
> > trace about detected version 5 of superblock when mounting volume which
> > was formatted using mkfs.xfs from 4.3.0.
>
> More recent xfsprogs versions enable features that are only
> supported by recent kernels. We tend to wait at least a year before
> enabling new features by default in xfsprogs so that kernel support
> is usually picke dup by distros before they update xfsprogs....
>
> If you have an old kernel, then you need to turn off the newer
> features that your kernel does not support. This has always been the
> case - if you update the xfsprogs yourself, then you need to use the
> correct options for your kernel. In general, this:
>
> # mkfs.xfs -f -m crc=0 -n ftype=0 <dev>
>
> will make a filesystem that can be mounted on old kernels. If
> distros are shipping old kernels with new xfsprogs and are not
> changing the default behaviour to suit their kernel, then that is a
> distro problem.

How about just checking running kernel version before enabling this by
default? Of course this doesn´t cover the case where one does mkfs.xfs from a
newer live distro and wants to mount with an older installed distro then. It
also makes sense to make it possible to override the default choice as it is
implemented right now.

Alternatively it would be an option to display a warning if by default a
feature is enabled that is not supported by the running kernel.

While this is some implementation effort, it may help to reduce questions on
this mailing list. And as you see distro problem or not: People still ask
here. :)

> As it is, in future the version of xfsprogs will tell you what
> kernel has the same feature support. i.e. xfsprogs 4.2.0 has exactly
> the same code/feature support as kernel 4.2.0. Similarly for
> xfsprogs/kernel 4.3.0. However, this won't prevent the fact that
> xfsprogs 4.8.0 might enable features that kernel 4.3.0 does not know
> about - the only way to prevent that sort of problem is to never
> enable new features in mkfs.xfs, and that's not a viable solution.

Nice to know. That is how btrfs-tools is versioned as well meanwhile.

Thanks,
--
Martin