On Wed, Sep 30, 2009 at 08:10:30PM +0800, Jens Axboe wrote:
> On Wed, Sep 30 2009, Jan Kara wrote:
> > > +void bdi_writeback_wait(struct backing_dev_info *bdi, long nr_pages)
> > > +{
> > > + struct dirty_throttle_task tt = {
> > > + .nr_pages = nr_pages,
> > > + .complete = COMPLETION_INITIALIZER_ONSTACK(tt.complete),
> > > + };
> > > + struct wb_writeback_args args = {
> > > + .sync_mode = WB_SYNC_NONE,
> > > + .nr_pages = LONG_MAX,
> > > + .range_cyclic = 1,
> > > + .for_background = 1,
> > > + };
> > > + struct bdi_work work;
> > > +
> > > + bdi_work_init(&work, &args);
> > > + work.state |= WS_ONSTACK;
> > > +
> > > + /*
> > > + * make sure we will be waken up by someone
> > > + */
> > > + bdi_queue_work(bdi, &work);
> > This is wrong, you shouldn't submit the work like this because you'll
> > have to wait for completion (wb_clear_pending below is just bogus). You
> > should rather do bdi_start_writeback(bdi, NULL, 0).
>
> Indeed, the above will die a horrible death fairly soon. But we can add
> some "barrier" like synchronization, if you just wish to wait for
> previously submitted work to have been completed.
Thanks, I just purged that hack and go for bdi_start_writeback :)
Thanks,
Fengguang
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