Re: [PATCH 2.6.27.y 1/3] ext4: Use our own write_cache_pages()

["Jayson R. King" <dev@jaysonking.com>]

On 05/28/2010 08:41 PM, Jayson R. King wrote:
> On 05/28/2010 07:49 PM, tytso@mit.edu wrote:
>> This doesn't fix a bug; it's to make it easy for Dave Chinner to make
>> some changes to fix XFS's performance and to undo some ext4-specific
>> changes to write_cache_pages(). I'm not sure there's a good reason to
>> backport this to 2.6.27.y....
>
> The difference is that, 2.6.27's write_cache_pages() in page-writeback.c
> still updates wbc->nr_to_write, since the patch which changed that
> behavior was dropped from .27-rc2 due to the XFS regression it causes on
> mainline.

I meant, it was dropped from .27.47-rc2 stable. Sorry for any confusion.

> ext4 appears to want the behavior of write_cache_pages which
> does not update wbc->nr_to_write. This write_cache_pages_da() does what
> ext4 wants, without introducing the XFS regression. So I believe it is
> needed.
>
> Did I mis-judge?
>
> Rgds,
>
> Jayson
>