[Cluster-devel] [PATCH 1/4] gfs2: stop using generic_writepages in gfs2_ail1_start_one

[Christoph Hellwig <hch@lst.de>]

On Wed, Jan 18, 2023 at 10:22:20PM +0100, Andreas Gruenbacher wrote:
> The above change means that instead of calling generic_writepages(),
> we end up calling filemap_fdatawrite_wbc() -> do_writepages() ->
> mapping->a_ops->writepages(). But that's something completely
> different; the writepages address space operation operates is outward
> facing, while we really only want to write out the dirty buffers /
> pages in the underlying address space. In case of journaled data
> inodes, gfs2_jdata_writepages() actually ends up trying to create a
> filesystem transaction, which immediately hangs because we're in the
> middle of a log flush.
> 
> So I'm tempted to revert the following two of your commits; luckily
> that's independent from the iomap_writepage() removal:
> 
>   d3d71901b1ea ("gfs2: remove ->writepage")
>   b2b0a5e97855 ("gfs2: stop using generic_writepages in gfs2_ail1_start_one")

generic_writepages is gone in linux-next, and I'd really like to keep
it that way.  So if you have to do this, please open code it
using write_cache_pages and a direct call to the writepage method of
choice.

> I think we could go through iomap_writepages() instead of
> generic_writepages() here as well,  but that's for another day.

Well, that would obviously be much better, and actually help with the
goal of removing ->writepage.