Re: [PATCHv3 1/5] bvec: introduce multi-page bvec iterating

[Ming Lei <ming.lei@redhat.com>]

On Tue, Nov 21, 2023 at 08:49:45AM -0700, Keith Busch wrote:
> On Tue, Nov 21, 2023 at 04:37:01PM +0800, Ming Lei wrote:
> > On Mon, Nov 20, 2023 at 02:40:54PM -0800, Keith Busch wrote:
> > > From: Keith Busch <kbusch@kernel.org>
> > > 
> > > Some bio_vec iterators can handle physically contiguous memory and have
> > > no need to split bvec consideration on page boundaries.
> > 
> > Then I am wondering why this helper is needed, and you can use each bvec
> > directly, which is supposed to be physically contiguous.
> 
> It's just a helper function to iterate a generic bvec.

I just look into patch 3 about the use, seems what you need is for_each_bvec_all(),
which is safe & efficient to use when freeing the host data(bio or bip), but can't
be used in split bio/bip, in which the generic iterator is needed.

And you can open-code it in bio_integrity_unmap_user():

for (i = 0; i < bip->bip_vcnt; i++) {
	struct bio_vec *v = &bip->bip_vec[i];

	...
}

Thanks,
Ming