Re: [PATCH v2 07/14] fs: iomap: Sub-extent zeroing

[John Garry]

On 06/03/2024 21:14, Dave Chinner wrote:
> > diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> > index bcd3f8cf5ea4..733f83f839b6 100644
> > --- a/fs/iomap/direct-io.c
> > +++ b/fs/iomap/direct-io.c
> > @@ -277,7 +277,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
> >   {
> >   	const struct iomap *iomap = &iter->iomap;
> >   	struct inode *inode = iter->inode;
> > -	unsigned int fs_block_size = i_blocksize(inode), pad;
> > +	unsigned int zeroing_size, pad;
> >   	loff_t length = iomap_length(iter);
> >   	loff_t pos = iter->pos;
> >   	blk_opf_t bio_opf;
> > @@ -288,6 +288,8 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
> >   	size_t copied = 0;
> >   	size_t orig_count;
> >   
> > +	zeroing_size = i_blocksize(inode) << iomap->extent_shift;
> The iomap interfaces use units of bytes for offsets, sizes, ranges,
> etc. Using shifts to define a granularity value seems like a
> throwback to decades old XFS code and just a bit weird nowdays.  Can
> we just pass this as a byte count? i.e.:
>
> 	zeroing_size = i_blocksize(inode);
> 	if (iomap->extent_size)
> 		zeroing_size = iomap->extent_size;

Fine

I was also thinking of something like i_extentsize() for vfs, which 
would save requiring adding iomap->extent_size, but decided to limit vfs 
changes.

Thanks,
John