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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,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 AD81FC352A4 for ; Mon, 10 Feb 2020 23:42:23 +0000 (UTC) Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7F95620708 for ; Mon, 10 Feb 2020 23:42:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=sourceforge.net header.i=@sourceforge.net header.b="Q/9IshEG"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=sf.net header.i=@sf.net header.b="MAVZKqwD" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7F95620708 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=linux-f2fs-devel-bounces@lists.sourceforge.net Received: from [127.0.0.1] (helo=sfs-ml-1.v29.lw.sourceforge.com) by sfs-ml-1.v29.lw.sourceforge.com with esmtp (Exim 4.90_1) (envelope-from ) id 1j1Ih4-0000Rp-TU; Mon, 10 Feb 2020 23:42:22 +0000 Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1j1Ih3-0000RM-6S for linux-f2fs-devel@lists.sourceforge.net; Mon, 10 Feb 2020 23:42:21 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=Sender:In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date: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=Zh/RztX/8oDfh+jXW0R+NP4WqX/kaOpXeIwx7w4PrVQ=; b=Q/9IshEGE+HZ4dWooHjbOZ6SJ 7C46o8hHRUSGysX4nCkLlTxzoveCgQW9GYGBdwFLLpBeLUJg9X1Qc+zXgJaHI48j7zdeIADIjruUQ gqogTC91ttdNnsEb9sljvKakgoIK51rDE0fdLySi86UQ/A/E9iPkgOTuz9kfpM4ehZHbM=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=Sender:In-Reply-To:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date: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=Zh/RztX/8oDfh+jXW0R+NP4WqX/kaOpXeIwx7w4PrVQ=; b=MAVZKqwDv/hnnDIl2EX8KXPFng I1Ua50NOLa5cA6eNp0fNun76nVAbHQzrl3bbYi181+i9gOCXPKbSjYY6nelgFEg1Mlm1vGTrPUs4P 8a7L/s03QznnKwm6D2y4WLGgZXXDmtDbZJJ6GZTrbzzSd8xwTzD4GN+i8lyIpEXcHas4=; Received: from zeniv.linux.org.uk ([195.92.253.2]) by sfi-mx-1.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.92.2) id 1j1Ih1-0081KA-DM for linux-f2fs-devel@lists.sourceforge.net; Mon, 10 Feb 2020 23:42:21 +0000 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j1Igp-00AcMq-LS; Mon, 10 Feb 2020 23:42:07 +0000 Date: Mon, 10 Feb 2020 23:42:07 +0000 From: Al Viro To: Daniel Rosenberg Message-ID: <20200210234207.GJ23230@ZenIV.linux.org.uk> References: <20200208013552.241832-1-drosen@google.com> <20200208013552.241832-3-drosen@google.com> <20200208021216.GE23230@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Headers-End: 1j1Ih1-0081KA-DM Subject: Re: [f2fs-dev] [PATCH v7 2/8] fs: Add standard casefolding support X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kernel-team@android.com, Theodore Ts'o , Jonathan Corbet , Richard Weinberger , Andreas Dilger , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, Eric Biggers , linux-fscrypt@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, Jaegeuk Kim , linux-ext4@vger.kernel.org, Gabriel Krisman Bertazi Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On Mon, Feb 10, 2020 at 03:11:13PM -0800, Daniel Rosenberg wrote: > On Fri, Feb 7, 2020 at 6:12 PM Al Viro wrote: > > > > On Fri, Feb 07, 2020 at 05:35:46PM -0800, Daniel Rosenberg wrote: > > > > > > Again, is that safe in case when the contents of the string str points to > > keeps changing under you? > > I'm not sure what you mean. I thought it was safe to use the str and > len passed into d_compare. Even if it gets changed under RCU > conditions I thought there was some code to ensure that the name/len > pair passed in is consistent, and any other inconsistencies would get > caught by d_seq later. Are there unsafe code paths that can follow? If you ever fetch the same byte twice, you might see different values. You need a fairly careful use of READ_ONCE() or equivalents to make sure that you don't get screwed over by that. Sure, ->d_seq mismatch will throw the result out, but you need to make sure you won't oops/step on uninitialized memory/etc. in process. It's not impossible to get right, but it's not trivial and you need all code working with that much more careful than normal for string handling. _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel