Re: [PATCH, 3.7-rc7, RESEND] fs: revert commit bbdd6808 to fallocate UAPI

Martin Steigerwald
2012-12-05T17:24:05Z

Am Mittwoch, 5. Dezember 2012 schrieb Theodore Ts'o:
> On Wed, Dec 05, 2012 at 05:18:43PM +0100, Martin Steigerwald wrote:
> > Dave provided technical reasons.
> >
> > First in the patch description and then in:
> >
> > https://lkml.org/lkml/2012/11/26/700
>
> There were no technical reasons. We are only reserving a bit. And
> different file systems don't support all of the various different
> fallocate flags already --- for example, not all file systems support
> the punch system call.
>
> Yes, I could create an entrely new ioctl() that looks just like
> fallocate, but supports the extra bit, just so that Dave and others
> don't have to be offended about the existence of that extra bit ---
> but Linus (and others) have considered ioctl()'s evil, since there is
> no type checking, and it's just silly to create a separate interface
> just because somebody doesn't think some other file system shouldn't
> implement a particular feature --- especially since it's not like
> we're have any kind of shortage of bits in the fallocate field.

Thanks for explaining your technical view about this. I appreciate it.

> Heck, I probably have more to complain about with the inode flags
> field, which were originally created specifically for ext2/3/4, and
> which has since been grabbed for use by other file systems, including
> btrfs. You haven't heard me kvetching because btrfs has grabbed
> btrfs-specific inode flags for nocow and notail... no one even bother
> to try to get it past the fs-devel shed painting crew before *those*
> bits were allocated --- and I am absolutely fine with that.

Thats no technical reason – thats exactly the process / patch review stuff
Linus does not seem to give a shit about at least with this topic.

That aside I wondered about that inode flags in earlier days already. At
some time chattr +i worked with XFS and then it only worked in Ext3.
Before that I thought that chattr stuff would work with all filesystems.

--
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
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