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.
--
Jens Axboe
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