netdev - Re: [PATCH 20/23] rxrpc: use bvec_set

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Message-ID: <3351918.1675077855@warthog.procyon.org.uk>
Date:   Mon, 30 Jan 2023 11:24:15 +0000
From:   David Howells <dhowells@...hat.com>
To:     Christoph Hellwig <hch@....de>
Cc:     dhowells@...hat.com, linux-block@...r.kernel.org,
        ceph-devel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        linux-nvme@...ts.infradead.org, linux-scsi@...r.kernel.org,
        target-devel@...r.kernel.org, kvm@...r.kernel.org,
        netdev@...r.kernel.org, linux-afs@...ts.infradead.org,
        linux-cifs@...r.kernel.org, samba-technical@...ts.samba.org,
        linux-fsdevel@...r.kernel.org, linux-nfs@...r.kernel.org,
        devel@...ts.orangefs.org, io-uring@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH 20/23] rxrpc: use bvec_set_page to initialize a bvec

Christoph Hellwig <hch@....de> wrote:

> On Mon, Jan 30, 2023 at 10:31:23AM +0000, David Howells wrote:
> > Christoph Hellwig <hch@....de> wrote:
> > 
> > > +		bvec_set_page(&bv, ZERO_PAGE(0), len, 0);
> > 
> > Maybe bvec_set_zero_page()?
> 
> Why?

Seems to be something people want to do quite a lot and don't know about.
I've seen places where someone allocates a buffer and clears it just to use as
a source of zeros.  There's at least one place in cifs, for example.  I know
about it from wrangling arch code, but most people working on Linux haven't
done that.

David