From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80D35C004D3 for ; Mon, 22 Oct 2018 16:18:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BFA762064C for ; Mon, 22 Oct 2018 16:18:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BFA762064C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728581AbeJWAhO convert rfc822-to-8bit (ORCPT ); Mon, 22 Oct 2018 20:37:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54904 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727877AbeJWAhO (ORCPT ); Mon, 22 Oct 2018 20:37:14 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 92B2E30014CF; Mon, 22 Oct 2018 16:18:05 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-113.rdu2.redhat.com [10.10.120.113]) by smtp.corp.redhat.com (Postfix) with ESMTP id B56325D777; Mon, 22 Oct 2018 16:18:01 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20181020050521.GJ32577@ZenIV.linux.org.uk> References: <20181020050521.GJ32577@ZenIV.linux.org.uk> <153999783767.866.7957078562330181644.stgit@warthog.procyon.org.uk> <153999785961.866.5674146318200239679.stgit@warthog.procyon.org.uk> To: Al Viro Cc: dhowells@redhat.com, linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 03/24] iov_iter: Add I/O discard iterator MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <17219.1540225080.1@warthog.procyon.org.uk> Content-Transfer-Encoding: 8BIT Date: Mon, 22 Oct 2018 17:18:00 +0100 Message-ID: <17220.1540225080@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.40]); Mon, 22 Oct 2018 16:18:05 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Al Viro wrote: > > @@ -1060,6 +1074,9 @@ void iov_iter_revert(struct iov_iter *i, size_t unroll) > > } > > unroll -= i->iov_offset; > > switch (iov_iter_type(i)) { > > + case ITER_DISCARD: > > + i->iov_offset = 0; > > + return; > > ... the hell? That makes no sense whatsoever; what, besides this and immediately > preceding part of iov_iter_revert() so much as looks at ->iov_offset for those? > Just have it bugger off before the > if (unroll <= i->iov_offset) { > i->iov_offset -= unroll; > return; > } > bit... I didn't want to add another case before that if I could avoid it. If iov_offset > unroll, the discard iterator really doesn't care. Maybe I should just ignore iov_offset for the discard iterator. David