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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=unavailable 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 577DBC433ED for ; Mon, 26 Apr 2021 17:17:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 13BFA61077 for ; Mon, 26 Apr 2021 17:17:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 13BFA61077 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 87B5A6B006C; Mon, 26 Apr 2021 13:17:25 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 851096B006E; Mon, 26 Apr 2021 13:17:25 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 719876B0070; Mon, 26 Apr 2021 13:17:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0091.hostedemail.com [216.40.44.91]) by kanga.kvack.org (Postfix) with ESMTP id 5429E6B006C for ; Mon, 26 Apr 2021 13:17:25 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 13FEB3655 for ; Mon, 26 Apr 2021 17:17:25 +0000 (UTC) X-FDA: 78075174450.25.D49AB4B Received: from zeniv-ca.linux.org.uk (zeniv-ca.linux.org.uk [142.44.231.140]) by imf30.hostedemail.com (Postfix) with ESMTP id 8E2CEE000125 for ; Mon, 26 Apr 2021 17:17:05 +0000 (UTC) Received: from viro by zeniv-ca.linux.org.uk with local (Exim 4.94 #2 (Red Hat Linux)) id 1lb4ob-008SGJ-Lx; Mon, 26 Apr 2021 17:14:33 +0000 Date: Mon, 26 Apr 2021 17:14:33 +0000 From: Al Viro To: David Howells Cc: linux-fsdevel@vger.kernel.org, Dave Wysochanski , Marc Dionne , "Matthew Wilcox (Oracle)" , Christoph Hellwig , linux-mm@kvack.org, linux-cachefs@redhat.com, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet , Jeff Layton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] iov_iter: Four fixes for ITER_XARRAY Message-ID: References: <161918448151.3145707.11541538916600921083.stgit@warthog.procyon.org.uk> <161918446704.3145707.14418606303992174310.stgit@warthog.procyon.org.uk> <3545034.1619392490@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3545034.1619392490@warthog.procyon.org.uk> X-Stat-Signature: qwudurcc3j5ef6q69r559x4czygad6fb X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 8E2CEE000125 Received-SPF: none (ftp.linux.org.uk>: No applicable sender policy available) receiver=imf30; identity=mailfrom; envelope-from=""; helo=zeniv-ca.linux.org.uk; client-ip=142.44.231.140 X-HE-DKIM-Result: none/none X-HE-Tag: 1619457425-298458 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Apr 26, 2021 at 12:14:50AM +0100, David Howells wrote: > Hi Al, > > I think this patch should include all the fixes necessary. I could merge > it in, but I think it might be better to tag it on the end as an additional > patch. Looks sane, but I wonder if it would've been better to deal with this > @@ -791,6 +791,8 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i) > curr_addr = (unsigned long) from; > bytes = curr_addr - s_addr - rem; > rcu_read_unlock(); > + i->iov_offset += bytes; > + i->count -= bytes; > return bytes; > } > }) by having your iterator check the return value of X callback and, having decremented .bv_len by return value, broke out of the loop. __label__ __bugger_off; xas_for_each(&xas, head, ULONG_MAX) { \ if (xas_retry(&xas, head)) \ continue; \ if (WARN_ON(xa_is_value(head))) \ break; \ if (WARN_ON(PageHuge(head))) \ break; \ for (j = (head->index < index) ? index - head->index : 0; \ j < thp_nr_pages(head); j++) { \ __v.bv_page = head + j; \ size_t left; offset = (i->xarray_start + skip) & ~PAGE_MASK; \ seg = PAGE_SIZE - offset; \ __v.bv_offset = offset; \ __v.bv_len = min(n, seg); \ left = (STEP); __v.bv_len -= left; n -= __v.bv_len; \ skip += __v.bv_len; \ if (!n || left) goto __bugger_off; } \ if (n == 0) \ break; \ } \ __bugger_off: Then rename iterate_and_advance() to __iterate_and_advance() and have #define iterate_and_advance(....., X) __iterate_and_advance(....., ((void)(X),0)) with iterate_all_kinds() using iterate_xarray(....,((void)(X),0) Then _copy_mc_to_iter() could use __iterate_and_advance(), getting rid of the need of doing anything special in case of short copy. OTOH, I can do that myself in a followup - not a problem.