Re: [RFC v2 02/11] fs/buffer: add a for_each_bh() for block_read_full_folio()

[Luis Chamberlain <mcgrof@kernel.org>]

On Mon, Dec 16, 2024 at 10:56:44AM -0800, Luis Chamberlain wrote:
> On Sat, Dec 14, 2024 at 04:02:53AM +0000, Matthew Wilcox wrote:
> > On Fri, Dec 13, 2024 at 07:10:40PM -0800, Luis Chamberlain wrote:
> > > -	do {
> > > +	for_each_bh(bh, head) {
> > >  		if (buffer_uptodate(bh))
> > >  			continue;
> > >  
> > > @@ -2454,7 +2464,9 @@ int block_read_full_folio(struct folio *folio, get_block_t *get_block)
> > >  				continue;
> > >  		}
> > >  		arr[nr++] = bh;
> > > -	} while (i++, iblock++, (bh = bh->b_this_page) != head);
> > > +		i++;
> > > +		iblock++;
> > > +	}
> > 
> > This is non-equivalent.  That 'continue' you can see would increment i
> > and iblock.  Now it doesn't.
> 
> Thanks, not sure how I missed that! With that fix in place I ran a full
> baseline against ext4 and all XFS profiles.
> 
> For ext4 the new failures I see are just:
> 
>   * generic/044
>   * generic/045
>   * generic/046

Oh my, these all fail on vanilla v6.12-rc2 so its not the code which is
at fault.

 Luis