Re: [PATCH 07/17] fs: icache atomic inodes_stat

[Andrew Morton]

On Thu, 30 Sep 2010 16:20:57 +1000 Dave Chinner <david@xxxxxxxxxxxxx> wrote:

> > > --- a/fs/fs-writeback.c
> > > +++ b/fs/fs-writeback.c
> > > @@ -764,7 +764,8 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb)
> > >  	wb->last_old_flush = jiffies;
> > >  	nr_pages = global_page_state(NR_FILE_DIRTY) +
> > >  			global_page_state(NR_UNSTABLE_NFS) +
> > > -			(inodes_stat.nr_inodes - inodes_stat.nr_unused);
> > > +			(atomic_read(&inodes_stat.nr_inodes) -
> > > +			atomic_read(&inodes_stat.nr_unused));
> > 
> > race bug.
> 
> What new race?  The code has gone from using subtraction of unlocked
> counters to using subtraction of unlocked atomic counters. I can't
> see any new race condition in that transformation....

Oh.  I assumed that all the above used to happen under inode_lock.

Coz that's wot the changelog told me :)
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