From patchwork Fri Jul 20 13:05:49 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Wilck X-Patchwork-Id: 10537501 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id C562360547 for ; Fri, 20 Jul 2018 13:41:12 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C1B3D29780 for ; Fri, 20 Jul 2018 13:41:12 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BFD7A297CC; Fri, 20 Jul 2018 13:41:12 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5F56229780 for ; Fri, 20 Jul 2018 13:41:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731652AbeGTO3c (ORCPT ); Fri, 20 Jul 2018 10:29:32 -0400 Received: from smtp2.provo.novell.com ([137.65.250.81]:32814 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731747AbeGTO3c (ORCPT ); Fri, 20 Jul 2018 10:29:32 -0400 Received: from apollon.suse.de.de (prv-ext-foundry1int.gns.novell.com [137.65.251.240]) by smtp2.provo.novell.com with ESMTP (TLS encrypted); Fri, 20 Jul 2018 07:41:07 -0600 From: Martin Wilck To: Jens Axboe , Jan Kara , Ming Lei , Christoph Hellwig Cc: Hannes Reinecke , Johannes Thumshirn , Kent Overstreet , linux-block@vger.kernel.org, Martin Wilck Subject: [PATCH v4 1/4] block: bio_iov_iter_get_pages: fix size of last iovec Date: Fri, 20 Jul 2018 15:05:49 +0200 Message-Id: <20180720130552.21432-2-mwilck@suse.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180720130552.21432-1-mwilck@suse.com> References: <20180720130552.21432-1-mwilck@suse.com> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP If the last page of the bio is not "full", the length of the last vector slot needs to be corrected. This slot has the index (bio->bi_vcnt - 1), but only in bio->bi_io_vec. In the "bv" helper array, which is shifted by the value of bio->bi_vcnt at function invocation, the correct index is (nr_pages - 1). v2: improved readability following suggestions from Ming Lei. v3: followed a formatting suggestion from Christoph Hellwig. Fixes: 2cefe4dbaadf ("block: add bio_iov_iter_get_pages()") Reviewed-by: Hannes Reinecke Reviewed-by: Ming Lei Reviewed-by: Jan Kara Reviewed-by: Christoph Hellwig Signed-off-by: Martin Wilck --- block/bio.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/block/bio.c b/block/bio.c index 67eff5e..489a430 100644 --- a/block/bio.c +++ b/block/bio.c @@ -912,16 +912,16 @@ EXPORT_SYMBOL(bio_add_page); */ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) { - unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt; + unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt, idx; struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt; struct page **pages = (struct page **)bv; - size_t offset, diff; + size_t offset; ssize_t size; size = iov_iter_get_pages(iter, pages, LONG_MAX, nr_pages, &offset); if (unlikely(size <= 0)) return size ? size : -EFAULT; - nr_pages = (size + offset + PAGE_SIZE - 1) / PAGE_SIZE; + idx = nr_pages = (size + offset + PAGE_SIZE - 1) / PAGE_SIZE; /* * Deep magic below: We need to walk the pinned pages backwards @@ -934,17 +934,15 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) bio->bi_iter.bi_size += size; bio->bi_vcnt += nr_pages; - diff = (nr_pages * PAGE_SIZE - offset) - size; - while (nr_pages--) { - bv[nr_pages].bv_page = pages[nr_pages]; - bv[nr_pages].bv_len = PAGE_SIZE; - bv[nr_pages].bv_offset = 0; + while (idx--) { + bv[idx].bv_page = pages[idx]; + bv[idx].bv_len = PAGE_SIZE; + bv[idx].bv_offset = 0; } bv[0].bv_offset += offset; bv[0].bv_len -= offset; - if (diff) - bv[bio->bi_vcnt - 1].bv_len -= diff; + bv[nr_pages - 1].bv_len -= nr_pages * PAGE_SIZE - offset - size; iov_iter_advance(iter, size); return 0;