Re: buffer cache & ufs changes (preliminary ffsv2 extattr support)

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Mon, Jan 16, 2012 at 04:37:57PM +0000, David Holland wrote:
> On Sun, Jan 15, 2012 at 08:37:37PM +0100, Manuel Bouyer wrote:
>  > I don't think I'll be able to have this ready for netbsd-6, but I now know
>  > this requires 2 changes that will require a kernel version bump, so theses
>  > changes needs to go in before netbsd-6 is branched so that full
>  > extended attributes support can be pulled up later.
>  > 
>  > The fisrt change is to the buffer cache.
> 
> My first reaction is that I don't think it's a good idea to make major
> changes to the buffer cache at this stage in a release cycle. It's not
> exactly the most robust or stable code we have in the system.

On the other hand, changing the kernel ABI in the release branch
is not a good idea either, given the state of the module subsystem ...

I wouldn't call this a major change. The alternative way (adding a b_type
member to struct buf) is even less intrusive; if the alternative (*2())
functions are not used it'll always be 0.

> 
> (Also, you're aware that it isn't used for file data blocks, right?)

It depends on what you call "file data". Directory data blocks ends
there AFAIK, as do symlink data blocks when the link's target doesn't
fit in the inode.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--