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imf28.hostedemail.com; dkim=none; spf=none (imf28.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1675081105; a=rsa-sha256; cv=none; b=mn3nEb4FMRhJY5oddCDH/6joMJrrnOlSIi2gaXfaLz2rVa72bpj7yjf07D07KZy3TuNq6n npgl5V3qMZyTFnVfzyfQ/Rmvle94thqiJsO5d1sjqC57S2QFQWXI/KQ2zKSMkLL/lLn14k I4zm4mETixlP3Glm5m1tUoPHXacKTFA= Received: by verein.lst.de (Postfix, from userid 2407) id 2E41068B05; Mon, 30 Jan 2023 13:18:21 +0100 (CET) Date: Mon, 30 Jan 2023 13:18:20 +0100 From: Christoph Hellwig To: David Howells Cc: Christoph Hellwig , 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 Message-ID: <20230130121820.GA18981@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> <3351918.1675077855@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3351918.1675077855@warthog.procyon.org.uk> User-Agent: Mutt/1.5.17 (2007-11-01) X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: w5cryiosun6fsqaoy4apzaxr1a8aqucg X-Rspamd-Queue-Id: 1497EC0009 X-HE-Tag: 1675081104-746298 X-HE-Meta: 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 zzHPZZyX SVYTScVzEcZ6a/5FbGucsH8aLP55aqV6nBAe2OVUm/BlKPWm+dFj7wGA07YrMbBUXTDDQnJB/QtUlvvTfs3AzaN6tqDG1bNQqV6fuBybLduiZYmF+KnUi1JjY1Q== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jan 30, 2023 at 11:24:15AM +0000, David Howells wrote: > Seems to be something people want to do quite a lot and don't know about. Hmm. Right now there is one case where it would be used, and there's about three that are and should be using bio_add_page. > 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. But we don't really need a helper for every possible page use for that. People just need to learn about ZERO_PAGE.