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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,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 C91AFC4338F for ; Thu, 19 Aug 2021 15:32:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A858B61051 for ; Thu, 19 Aug 2021 15:32:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239578AbhHSPc6 (ORCPT ); Thu, 19 Aug 2021 11:32:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58460 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238663AbhHSPc5 (ORCPT ); Thu, 19 Aug 2021 11:32:57 -0400 Received: from mail-pj1-x1031.google.com (mail-pj1-x1031.google.com [IPv6:2607:f8b0:4864:20::1031]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 21B19C061575 for ; Thu, 19 Aug 2021 08:32:21 -0700 (PDT) Received: by mail-pj1-x1031.google.com with SMTP id oa17so5230119pjb.1 for ; Thu, 19 Aug 2021 08:32:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=evXAogE912+oXRWnnBTByvWfoAPmg/tID/FsWt9WDWA=; b=j3dLa7D3tiyVogDuYEBvto1iTmJLkhh3XnT+FiPZh0u2zLw0bsO50oHgnC0K8PheBR kq1X/qE8OFhqjLWO3wEn3J4xtolGLbGJpZMHmpcDNQOnaQg+LMPAM0V6X82nnJI3VcAZ WtQOl/oYSe+MAqx4XLIPUhVjm49jzz5g3tWlUFZ307DPTMKOcl7Ftt+85CkEHUg88si2 GVDcMyjvCmtN9WNlziyadUlPKWhWHwq+zaBAXUW1mQdl2sKD7Sydp1jVQUYsi/0rmvwb Ce4F2HPAulofMYI9F1OEH4053h0GZqw6lvJSaJ6J7LnwLSAW4x3Cebv0sUDz2rNZyliK JCtg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=evXAogE912+oXRWnnBTByvWfoAPmg/tID/FsWt9WDWA=; b=h0dc+i4i6emmdOmEq65mkhMDDtFJUhbuVXWV+qcvwxSyYyZsAxD6r0S5kGqJvW/sAu wDg9MBz2kIyRoq0+pvAJn6pLbPQtafnK1+ghD6aBY/E6PrJdLJS0c1WSjTvvLr4uJUVT m/0VV//DS7Zj+Jk7LC4D/B4SLIpU3zZS1ahp5LHvzA+Ch+9TGPsWaVjDlEaulLeKdfIF n0GprmJP7gqxOP8tCZTVGSYxDaE2l4qbR6qpDDTR3cGmhk/WRls01RmICpMcE5s2/I5o 81rsNs9RFW/tOTtb1xCmEWAnD+9zwwXsAojnTQz6kZ8URgXn7wtuU3nRwG3QZudJjhg6 pXFQ== X-Gm-Message-State: AOAM533zmxmrndQy1Ef9AgWcwREskJ1kWDCuqGnIFTpxZkNHMjBWGJQq 4zix5TCF8sycb2afYMClyqopZq5myGa86g== X-Google-Smtp-Source: ABdhPJx8yMGvxLU7zzifGkYCL07GRqrki3kNdc87bbatMjVGAJV9huWCxj1RSgV5MzW9wb4Z7XwZ3g== X-Received: by 2002:a17:90b:4d0c:: with SMTP id mw12mr16194200pjb.123.1629387140681; Thu, 19 Aug 2021 08:32:20 -0700 (PDT) Received: from realwakka ([59.12.165.26]) by smtp.gmail.com with ESMTPSA id c2sm3948668pfp.138.2021.08.19.08.32.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Aug 2021 08:32:20 -0700 (PDT) Date: Thu, 19 Aug 2021 15:32:16 +0000 From: Sidong Yang To: Nikolay Borisov Cc: linux-btrfs Subject: Re: [PATCH] btrfs: reflink: Assure length != 0 in btrfs_extent_same() Message-ID: <20210819153216.GD1987@realwakka> References: <20210818160815.1820-1-realwakka@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Thu, Aug 19, 2021 at 11:04:58AM +0300, Nikolay Borisov wrote: > > > On 18.08.21 г. 19:08, Sidong Yang wrote: > > btrfs_extent_same() cannot be called with zero length. Because when > > length is zero, it would be filtered by condition in > > btrfs_remap_file_range(). But if this function is used in other case in > > future, it can make ret as uninitialized. > > > > Signed-off-by: Sidong Yang > > This is not sufficient, with the assert compiled out the error would > still be in place. It seem that it is sufficient to initialize ret to > some non-arbitrary value i.e -EINVAL ? I agree. It's better way to assign intial value than adding assert. If there is code that initialize ret, It seems that assert is no need for this. > > > --- > > fs/btrfs/reflink.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/fs/btrfs/reflink.c b/fs/btrfs/reflink.c > > index 9b0814318e72..69eb50f2f0b4 100644 > > --- a/fs/btrfs/reflink.c > > +++ b/fs/btrfs/reflink.c > > @@ -653,6 +653,7 @@ static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen, > > u64 i, tail_len, chunk_count; > > struct btrfs_root *root_dst = BTRFS_I(dst)->root; > > > > + ASSERT(olen); > > spin_lock(&root_dst->root_item_lock); > > if (root_dst->send_in_progress) { > > btrfs_warn_rl(root_dst->fs_info, > >