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

[Al Viro]

On Fri, Jan 02, 2009 at 08:09:03PM +0100, Oleg Nesterov wrote:
> On 01/02, Al Viro wrote:
> >
> > Bloating with mutex is over the top, indeed, but why can't we simply keep
> > a pointer to fasync_struct in there?  Do we ever have a struct file with
> > several fasync_struct?
> 
> pipe_rdwr_fasync() ?

Ho-hum...  Right you are ;-/

FWIW, it's still bloody tempting to try.  How about hlist from struct file
through fasync_struct?  Possibly with reference from fasync_struct back
to the queue it's on, while we are at it - would make fasync_helper simpler...