Re: [PATCH 3/7] iomap: add bioset in iomap_read_folio_ops for filesystems to use own bioset

["Darrick J. Wong" <djwong@kernel.org>]

On Thu, Mar 13, 2025 at 01:53:59PM +0000, Matthew Wilcox wrote:
> On Mon, Feb 03, 2025 at 10:43:07AM +0100, Christoph Hellwig wrote:
> > Allocate the bio from the bioset provided in iomap_read_folio_ops.
> > If no bioset is provided, fs_bio_set is used which is the standard
> > bioset for filesystems.
> 
> It feels weird to have an 'ops' that contains a bioset rather than a
> function pointer.  Is there a better name we could be using?  ctx seems
> wrong because it's not a per-op struct.

"profile" is the closest I can come up with, and that feels wrong to me.
There's at least some precedent in fs-land for ops structs that have
non-function pointer fields such as magic numbers, descriptive names,
or crc block offsets.

--D

> 
> > +++ b/include/linux/iomap.h
> > @@ -311,6 +311,12 @@ struct iomap_read_folio_ops {
> >  	 */
> >  	void (*submit_io)(struct inode *inode, struct bio *bio,
> >  			  loff_t file_offset);
> > +
> > +	/*
> > +	 * Optional, allows filesystem to specify own bio_set, so new bio's
> > +	 * can be allocated from the provided bio_set.
> > +	 */
> > +	struct bio_set *bio_set;
> >  };
>