Re: [Ext2-devel] [RFC 0/13] extents and 48bit ext3

[Jeff Garzik]

Stephen C. Tweedie wrote:
> Hi,
>
> On Fri, 2006-06-09 at 11:56 -0400, Jeff Garzik wrote:
>
> > Think about how this will be deployed in production, long term.
> >
> > If extents are not made default at some point, then no one will use the 
> > feature, and it should not be merged.
>
> Features such as ACLs and SELinux are still not on by default and are
> most *definitely* used.  This is a bogus argument.

They are on in SElinux-enabled distro installs, AFAIK?


> > And when extents are default, you have this blizzard-of-feature-flags 
> > stealth upgrade event occur _sometime_ after they boot into the new fs 
> > for the first time.
>
> No.  I don't see it ever being forced on in the kernel by default, so
> there will be no such "stealth upgrades".
>
> Rather, if it is "made default", that will be done by setting the flag
> by default on newly-created filesystems in mke2fs.  We won't be playing
> magic on existing filesystems.
>
> And to avoid confusion, I am *entirely* open to the idea of making it
> only ever default to on in mke2fs at some point in the future where we
> batch a set of incompat features with the "ext4" label, so that "mke2fs
> -O ext4", or "mke4fs", would set it.  That has already been proposed on
> ext2-devel; we're nowhere near the stage of making that default yet.

Sure.  And why not bundle that with a vehicle for separating out the 
_code_ that deals with ancient formats versus newer formats.  A vehicle 
that enables the existing ext3 stuff to stabilize and freeze, while 
enabling parallel development of new features.

	Jeff


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