[xfs-masters] RFC: Fix f_flags races without the BKL

[Andi Kleen]

On Mon, Dec 29, 2008 at 01:41:51PM +0100, Oleg Nesterov wrote:
> On 12/29, Jonathan Corbet wrote:
> >
> > After pondering for a while, I couldn't come up with anything better than a
> > global file->f_flags mutex.  There's no point in bloating struct file with
> > a mutex just for this purpose; it's hard to imagine that there will be any
> > real contention for this lock.
> 
> Yes, this patch is simple and straightforward, but now we can't change
> ->f_flags in non-preempible context. And the global lock is not very
> nice anyway.
> 
> Once again, can't we use O_LOCK_FLAGS bit? I agree, it is a bit ugly,
> and I won't insist if you don't like is.

I would prefer O_LOCK_FLAGS bit too. The global lock is not very nice
and I don't doubt someone will come up with a workload which
pounds on it.

-Andi
-- 
ak at linux.intel.com