[Cluster-devel] [PATCH v2 1/2] iomap: Don't create iomap_page objects for inline files

[Andreas Gruenbacher]

On Tue, Jul 6, 2021 at 7:07 AM Christoph Hellwig <hch at infradead.org> wrote:
> On Mon, Jul 05, 2021 at 08:18:23PM +0200, Andreas Gruenbacher wrote:
> > In iomap_readpage_actor, don't create iop objects for inline inodes.
> > Otherwise, iomap_read_inline_data will set PageUptodate without setting
> > iop->uptodate, and iomap_page_release will eventually complain.
> >
> > To prevent this kind of bug from occurring in the future, make sure the
> > page doesn't have private data attached in iomap_read_inline_data.
> >
> > Signed-off-by: Andreas Gruenbacher <agruenba at redhat.com>
> > Reviewed-by: Matthew Wilcox (Oracle) <willy at infradead.org>
>
> As mentioned last round I'd prefer to simply not create the iomap_page
> at all in the readpage/readpages path.

I've tried that by replacing the iomap_page_create with to_iomap_page
in iomap_readpage_actor and with that, I'm getting a
VM_BUG_ON_PAGE(!PageLocked(page)) in iomap_read_end_io -> unlock_page
with generic/029. So there's obviously more to it than just not
creating the iomap_page in iomap_readpage_actor.

Getting rid of the iomap_page_create in iomap_readpage_actor
completely isn't a necessary part of the bug fix. So can we focus on
the bug fix for now, and worry about the improvement later?

> Also this patch needs to go after the current patch 2 to be bisection clean.

Yes, makes sense.

Thanks,
Andreas