Alexander Viro writes:
>
> On Tue, 13 Jun 2000, Richard Gooch wrote:
>
> > I'd like to see something more drastic. Indeed, that union crap is by
> > far the worst offender and needs fixing. But there's a whole pile of
> > other junk that's just not needed all the time.
>
> Richard, may I remind you that we are supposed to be in the freeze?
> There may be a chance to trim the union down _and_ get it into 2.4.
??? Didn't you read the other parts of my message. Quoting myself:
> Besides, there's also the problem of getting efficiency improvements
> into the mainline kernel. I don't expect Linus would let us fix these
> things so close to 2.4.
And here you quote me:
> > Yeah, but 2.4 is too close. Such a change is going to require a fair
> > bit of surgery for all filesystems.
So I don't really expect wholesale VFS changes right now (but, hey,
that doesn't seem to stop you getting stuff in;-). But that shouldn't
stop us talking about where to go from here.
> You don't need it on all filesystems.
So you're thinking of attacking just the worst offenders?
> > I still prefer my idea of splitting the dcache and icache so that you
> > can maintain a populated dentry tree without keeping the inodes
> > hanging around as well. This seems far less invasive and also brings
> > even more space savings.
>
> Less invasive??? It requires a lot of changes in the internal VFS
> locking protocol. And that affects (in non-obvious ways) every
> friggin' code path in namei.c and dcache.c. It's going to happen,
> but that's _not_ a 2.4.early stuff. Sorry. Just too high potential
> of introducing a lot of new and interesting races. I will fork
> VFS-CURRENT after 2.4.0 release, then such stuff may go there
> without destabilising 2.4. Maybe some parts will be possible to fold
> back during 2.4, but complete thing will not be merged until
> 2.5.early.
OK, so you're assuming that shrinking the union will be done by only
attacking a small number of filesystems. In that case, it will
probably be less invasive that splitting the dcache and icache.
However, ultimately I'd like to see the union thrown out entirely.
And also have the dcache and icache split.
BTW: for 2.4, my main focus is on ensuring there aren't any races in
devfs. The recent changes should make things a lot better :-)
Regards,
Richard....
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