On Tue, Nov 15, 2011 at 09:41:27PM +0800, Jan Kara wrote:
> On Tue 15-11-11 19:48:44, Wu Fengguang wrote:
> > > +static int balance_dirty_pages(struct address_space *mapping,
> > > unsigned long pages_dirtied)
> > > {
> > > unsigned long nr_reclaimable; /* = file_dirty + unstable_nfs */
> > > @@ -1020,6 +1023,7 @@ static void balance_dirty_pages(struct address_space *mapping,
> > > unsigned long pos_ratio;
> > > struct backing_dev_info *bdi = mapping->backing_dev_info;
> > > unsigned long start_time = jiffies;
> > > + int err = 0;
> > >
> > > for (;;) {
> > > /*
> > > @@ -1133,7 +1137,7 @@ pause:
> > > pages_dirtied,
> > > pause,
> > > start_time);
> > > - __set_current_state(TASK_UNINTERRUPTIBLE);
> > > + __set_current_state(TASK_KILLABLE);
> > > io_schedule_timeout(pause);
> > >
> > > dirty_thresh = hard_dirty_limit(dirty_thresh);
> > > @@ -1145,6 +1149,11 @@ pause:
> > > */
> > > if (nr_dirty < dirty_thresh)
> > > break;
> > > +
> > > + if (fatal_signal_pending(current)) {
> > > + err = -EINTR;
> > > + break;
> > > + }
> > > }
> >
> > The other alternative is to raise the limit on fatal_signal_pending:
> >
> > if (fatal_signal_pending(current) &&
> > nr_dirty < dirty_thresh + dirty_thresh / 2)
> > break;
> >
> > That should work well enough in practice and avoids touching the fs code.
> Sorry, but I fail to see what would this bring us... Can you elaborate a
> bit please?
It's not bringing us something, but allows us to get rid of patch 2
as well as adding fatal_signal_pending() tests to all the other fs.
So no more worries about partial writes :)
Sure it leaves ->write_begin() blocks unhandled, however that should
be much less a problem than the blocks inside balance_dirty_pages().
Thanks,
Fengguang
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