Re: [PATCH 2/8] writeback: move dirty inodes from super_block tobacking_dev_info
From: Jens Axboe
Date: Fri Sep 11 2009 - 03:47:29 EST
On Tue, Sep 08 2009, Christoph Hellwig wrote:
>
On Sun, Sep 06, 2009 at 08:43:59PM +0200, Jens Axboe wrote:
>
> On Fri, Sep 04 2009, Christoph Hellwig wrote:
>
> > On Fri, Sep 04, 2009 at 08:53:57AM +0200, Jens Axboe wrote:
>
> > > > + if (wbc->sync_mode == WB_SYNC_ALL)
>
> > > > + bdi_wait_on_work_clear(&work);
>
> > > > }
>
> > >
>
> > > That doesn't work, you have to wait for on-stack work. So either we just
>
> > > punt and not do anything for WB_SYNC_NONE if the allocation fails, or we
>
> > > punt to stack and do the wait. Since it's a cleaning action and
>
> > > allocation fails, falling back to the stack and waiting seems like the
>
> > > most appropriate choice.
>
> >
>
> > True, the wait needs to be unconditional. Updated version below.
>
>
>
> (did you forget that patch? it's not there).
>
>
Here we go, sorry:
I have applied this to a postmerge writeback branch. I made one change,
though:
>
+ if (wbc->sync_mode != WB_SYNC_ALL) {
>
+ struct bdi_work *w = bdi_alloc_work(wbc);
>
+ if (w) {
>
+ bdi_queue_work(wbc->bdi, w);
>
+ return;
>
+ }
We should make that bdi_queue_work() unconditional, if you want to make
sure that we current thread wakes up and actually flushes some old data
when allocation fails.
void bdi_start_writeback(struct writeback_control *wbc)
{
/*
* WB_SYNC_NONE is opportunistic writeback. If this allocation fails,
* bdi_queue_work() will wake up the thread and flush old data. This
* should ensure some amount of progress in freeing memory.
*/
if (wbc->sync_mode != WB_SYNC_ALL) {
struct bdi_work *w = bdi_alloc_work(wbc);
bdi_queue_work(wbc->bdi, w);
} else {
struct bdi_work work;
bdi_work_init(&work, wbc);
work.state |= WS_ONSTACK;
bdi_queue_work(wbc->bdi, &work);
bdi_wait_on_work_clear(&work);
}
}
--
Jens Axboe
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
http://vger.kernel.org/majordomo-info.html
Please read the FAQ at
http://www.tux.org/lkml/