Re: [PATCH v2 3/7] buffer: Fix grow_buffers() for block size > PAGE_SIZE

[Matthew Wilcox <willy@xxxxxxxxxxxxx>]

On Fri, Nov 10, 2023 at 08:29:41PM +0900, Ryusuke Konishi wrote:
> On Fri, Nov 10, 2023 at 3:37 PM Ryusuke Konishi wrote:
> > > +       return grow_dev_folio(bdev, block, pos / PAGE_SIZE, size, gfp);
> >
> > "pos" has a loff_t type (= long long type).
> > Was it okay to do C division directly on 32-bit architectures?
> 
> Similar to the comment for patch 5/7, can we safely use the generally
> less expensive shift operation "pos >> PAGE_SHIFT" here ?

If your compiler sees x / 4096 and doesn't optimise it to x >> 12,
you need a better compiler.