Re: [RFC PATCH V2] iomap: add support to track dirty state of sub pages

[Matthew Wilcox]

On Tue, Aug 18, 2020 at 09:12:29AM -0700, Darrick J. Wong wrote:
> On Tue, Aug 18, 2020 at 04:53:05PM +0100, Matthew Wilcox wrote:
> > It would be better to use the same wording as below:
> > 
> > > +	bitmap_zero(iop->state, PAGE_SIZE * 2 / SECTOR_SIZE);
> 
> ISTR there was some reason why '512' was hardcoded in here instead of
> SECTOR_SIZE.  I /think/ it was so that iomap.h did not then have a hard
> dependency on blkdev.h and everything else that requires...

That ship already sailed.  I over-trimmed this line:

-       bitmap_zero(iop->uptodate, PAGE_SIZE / SECTOR_SIZE);

Looks like Christoph changed his mind sometime between that message
and the first commit: 9dc55f1389f9569acf9659e58dd836a9c70df217

My THP patches convert the bit array to be per-block rather than
per-sector, so this is all going to go away soon ;-)

> https://lore.kernel.org/linux-xfs/20181215105155.GD1575@xxxxxx/