Re: [patch 1/2] ufd v1 - unsequential O(1) fdmap core

From: Davide Libenzi
Date: Mon Jun 04 2007 - 13:57:46 EST


On Mon, 4 Jun 2007, Andrew Morton wrote:

> > must be RCU friendly (proper barriers) since it's used in
> > lockless code,
>
> Haven't looked at that.
>
> > and must have flags associated to an allocation.
>
> Don't understand that.

It needs to be able to store flags (like close-on-exec, and maybe more)
together with a file*.


> > And I'm
> > leaving out the O(1) part, that for something like this, is just silly not
> > to have it. This is really an array.
>
> Having to walk down a tree in fget_light() would kinda suck.
>
> What about my b)?

Right now, I'm working on a patch that uses fdmap even for legacy
(sequential) fd allocations. With a cleaner interface, w/out having code
all around the kernel that access fdtable members directly. This should
cut some code WRT using two different allocators (code in fs/file.c will
almost zip-away), and maybe it'll look even better and have some new
comments too ;)
It can be, in theory, completely abstracted and moved into lib/. I'll look
into it once I completed the first cleanup, assuming the whole thing won't
look worse than before :)



- Davide


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