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From:   David Howells <dhowells@redhat.com>
In-Reply-To: <20230130103343.GA11663@lst.de>
References: <20230130103343.GA11663@lst.de> <20230130092157.1759539-21-hch@lst.de> <20230130092157.1759539-1-hch@lst.de> <3347459.1675074683@warthog.procyon.org.uk>
To:     Christoph Hellwig <hch@lst.de>
Cc:     dhowells@redhat.com, linux-block@vger.kernel.org,
        ceph-devel@vger.kernel.org,
        virtualization@lists.linux-foundation.org,
        linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org,
        target-devel@vger.kernel.org, kvm@vger.kernel.org,
        netdev@vger.kernel.org, linux-afs@lists.infradead.org,
        linux-cifs@vger.kernel.org, samba-technical@lists.samba.org,
        linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org,
        devel@lists.orangefs.org, io-uring@vger.kernel.org,
        linux-mm@kvack.org
Subject: Re: [PATCH 20/23] rxrpc: use bvec_set_page to initialize a bvec
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Content-ID: <3351917.1675077855.1@warthog.procyon.org.uk>
Date:   Mon, 30 Jan 2023 11:24:15 +0000
Message-ID: <3351918.1675077855@warthog.procyon.org.uk>
Precedence: bulk

Christoph Hellwig <hch@lst.de> wrote:

> On Mon, Jan 30, 2023 at 10:31:23AM +0000, David Howells wrote:
> > Christoph Hellwig <hch@lst.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