Re: regression in page writeback

[Wu Fengguang <fengguang.wu@intel.com>]

On Mon, Sep 28, 2009 at 09:08:04PM +0800, Christoph Hellwig wrote:
> On Mon, Sep 28, 2009 at 03:15:07PM +0800, Wu Fengguang wrote:
> > +		if (!PageActive(page))
> > +			SetPageReclaim(page);
> > +		err = mapping->a_ops->writepage(page, wbc);
> > +		if (err < 0)
> > +			handle_write_error(mapping, page, res);
> > +		if (err == AOP_WRITEPAGE_ACTIVATE) {
> > +			ClearPageReclaim(page);
> > +			res = PAGE_ACTIVATE;
> > +			break;
> > +		}
> 
> This should help a bit for XFS as it historically does multi-page
> writeouts from ->writepages (and apprently btrfs that added some

->writepage ?

> write-around recently?) but not those brave filesystems only
> implementing the multi-page writeout from writepages as designed.

Thanks.  Just tried write_cache_pages(), looks simple. Need to further
convert all aops->writepages to support lumpy pageout :)

> But really, the best would be to leave the writeout to the flusher
> threads and just reclaim the clean pages from the VM.

Yup, that's much larger behavior change, and could be pursued as a
long term goal.

Thanks,
Fengguang