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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 E5703C43603 for ; Wed, 18 Dec 2019 19:21:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B47A8206D7 for ; Wed, 18 Dec 2019 19:21:53 +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="igYrT7pk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727533AbfLRTVw (ORCPT ); Wed, 18 Dec 2019 14:21:52 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:48988 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727367AbfLRTVw (ORCPT ); Wed, 18 Dec 2019 14:21:52 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=WeW+VRLeMZJzYni3rjboMFgKf7w4L/Z6i8nVtxefrWQ=; b=igYrT7pkArJInRCn2HvudFpeQ 4/Y7nWsP/q4E6FIbmdEk9z42j0nBzQL58sT3RxKWiM+4Mfe8XfTHyujpdq2OPJ1DGDGUnTlH0/j+y xaD21T5ZNtH5dEiFNAkmc6OeEvHN4w7ufKmttR9NCHAnejfMePx79c1FgWlzrmBoxP9cDjjixWuiN T8sxYZjvema0JpzXyWcftkKu6eS3v6EMqpPg404NTsQvXNOQ++CzO3jeSDIp/4ATRSoec/iviYsAO xKhTKKHM3ZvRS0sgTZxJFFDAo3TkYjVP7QIHFU1Ercgsr6Ydnj7/FIIBkei+hXzZWygrYTCvThFkj T+/2P2+Rg==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1ihetE-0006ZI-A3; Wed, 18 Dec 2019 19:21:44 +0000 Date: Wed, 18 Dec 2019 11:21:44 -0800 From: Matthew Wilcox To: "Darrick J. Wong" Cc: Andreas Gruenbacher , Alexander Viro , Christoph Hellwig , Linus Torvalds , linux-kernel@vger.kernel.org, Jeff Layton , Sage Weil , Ilya Dryomov , Theodore Ts'o , Andreas Dilger , Jaegeuk Kim , Chao Yu , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Richard Weinberger , Artem Bityutskiy , Adrian Hunter , ceph-devel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mtd@lists.infradead.org, Chris Mason , Josef Bacik , David Sterba , linux-btrfs@vger.kernel.org, Jan Kara Subject: Re: [PATCH v3] fs: Fix page_mkwrite off-by-one errors Message-ID: <20191218192144.GF32169@bombadil.infradead.org> References: <20191218130935.32402-1-agruenba@redhat.com> <20191218185216.GA7497@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191218185216.GA7497@magnolia> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 18, 2019 at 10:52:16AM -0800, Darrick J. Wong wrote: > > @@ -9016,13 +9016,11 @@ vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf) > > ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */ > > again: > > lock_page(page); > > - size = i_size_read(inode); > > > > - if ((page->mapping != inode->i_mapping) || > > - (page_start >= size)) { > > - /* page got truncated out from underneath us */ > > + ret2 = page_mkwrite_check_truncate(page, inode); > > + if (ret2 < 0) > > goto out_unlock; > > ...here we try to return -EFAULT as vm_fault_t. Notice how btrfs returns > VM_FAULT_* values directly and never calls block_page_mkwrite_return? I > know dsterba acked this, but I cannot see how this is correct? I think you misread it. 'ret2' is never returned; we'll end up returning VM_FAULT_NOPAGE here. Arguably it should be SIGBUS or something, but I think retrying the fault will also end up giving a SIGBUS.