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=-6.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 29070C433E1 for ; Fri, 21 Aug 2020 06:07:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0129B207DA for ; Fri, 21 Aug 2020 06:07:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="qTzxO5uk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727097AbgHUGHR (ORCPT ); Fri, 21 Aug 2020 02:07:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50776 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725268AbgHUGHR (ORCPT ); Fri, 21 Aug 2020 02:07:17 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E5694C061385; Thu, 20 Aug 2020 23:07:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=csBfSNWoqycX+qwrSd8VYEM/dpU2DB6oNeP8NG+28Xc=; b=qTzxO5ukJYkNNSGikvE5RnQCsQ +KhwGfIq6hKk3uBbnfLAgUR6FOhqgOt59pJRlc0mbEP8P4TjhIuEZGm4ZoWQ5tHFIPDTLxVx3sE7F 7xfpj0y+M3F4xbaUxu+WQAk/K7vicbV335ik6f4aVmA5z0XxD5zPq3ld4vSv42DrYWQMkfC7lXOEC 69UtcSsu2hfM4jhvRLl5r/P8l8UgaIOV0jsqM9XRd7i9P//Oowm/NKHFN800e6HDD2igBVHRvF79f 8hsaUc3M6hvOlT4S5EGBd2yDs1FLYAilAgstS28qEoeSxvHfcH49rBEXEKfH2ZwQSLRl2YgW+zm76 BaSKRdoA==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1k90Cl-0000M6-0v; Fri, 21 Aug 2020 06:07:11 +0000 Date: Fri, 21 Aug 2020 07:07:10 +0100 From: Christoph Hellwig To: Anju T Sudhakar Cc: hch@infradead.org, darrick.wong@oracle.com, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, willy@infradead.org, riteshh@linux.ibm.com, linux-block@vger.kernel.org Subject: Re: [PATCH] iomap: Fix the write_count in iomap_add_to_ioend(). Message-ID: <20200821060710.GC31091@infradead.org> References: <20200819102841.481461-1-anju@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200819102841.481461-1-anju@linux.vnet.ibm.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Aug 19, 2020 at 03:58:41PM +0530, Anju T Sudhakar wrote: > From: Ritesh Harjani > > __bio_try_merge_page() may return same_page = 1 and merged = 0. > This could happen when bio->bi_iter.bi_size + len > UINT_MAX. > Handle this case in iomap_add_to_ioend() by incrementing write_count. > This scenario mostly happens where we have too much dirty data accumulated. > > w/o the patch we hit below kernel warning, I think this is better fixed in the block layer rather than working around the problem in the callers. Something like this: diff --git a/block/bio.c b/block/bio.c index c63ba04bd62967..ef321cd1072e4e 100644 --- a/block/bio.c +++ b/block/bio.c @@ -879,8 +879,10 @@ bool __bio_try_merge_page(struct bio *bio, struct page *page, struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1]; if (page_is_mergeable(bv, page, len, off, same_page)) { - if (bio->bi_iter.bi_size > UINT_MAX - len) + if (bio->bi_iter.bi_size > UINT_MAX - len) { + *same_page = false; return false; + } bv->bv_len += len; bio->bi_iter.bi_size += len; return true;