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

Jeff Garzik
2006-06-10T14:54:23Z

Christoph Hellwig wrote:
> On Sat, Jun 10, 2006 at 03:49:46PM +0200, Adrian Bunk wrote:
>>> And no real-world near-term progress is made for production users with
>>> modern requirements. What you're advocating breeds instability in the
>>> near-term.
>> There's also the old-fashioned "no regressions" requirement.
>>
>> You are trading near-term instability for the few users with "modern
>> requirements" against possible regressions for a large userbase.
>
> Alex mentioned a few times that the extents code just adds three if.
> I'm pretty sure that will not give you any regressions in the existing
> codebase. Can we concentrate on the more useful discussion topics now?

Alex is off by an order of magnitude. I've re-read the 13-patch series,
and this is the result of the review:

There are _five_ "if (new) .. else .." constructs added in JBD alone.

Three added in extent map support.

Twenty-seven (27) such constructs in 48-bit physical block support.

Two more in 48-bit ACL support.

And finally, the superblock changes don't add any branches, like the
other code does, but it does double the endian conversion work that
-every- user must do, even if they don't use 48bit at all.

Jeff