Re: [PATCH v2 16/16] iomap: Make readpage synchronous

[Christoph Hellwig]

On Thu, Oct 15, 2020 at 08:03:12PM +0100, Matthew Wilcox wrote:
> I honestly don't see the problem.  We have to assign the status
> conditionally anyway so we don't overwrite an error with a subsequent
> success.

Yes, but having a potential NULL pointer to a common structure is just
waiting for trouble.

> 
> > True.  I'd still prefer the AOP_UPDATED_PAGE as the fallthrough case
> > and an explicit goto out_unlock, though.
> 
> So this?
> 
>         if (ctx.bio) {
>                 submit_bio(ctx.bio);
>                 wait_for_completion(&ctx.done);
>                 if (ret < 0)
>                         goto err;
>                 ret = blk_status_to_errno(ctx.status);
>         }
> 
>         if (ret < 0)
>                 goto err;
>         return AOP_UPDATED_PAGE;
> err:
>         unlock_page(page);
>         return ret;
> 

Looks good.