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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 37C68C282CE for ; Wed, 10 Apr 2019 00:46:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F3725217F4 for ; Wed, 10 Apr 2019 00:46:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554857185; bh=oIWDtTvz1vibsjrk4J5eD/OHob32N5Dx/zh+H/G/qSc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=JSzzh979NXQRH/KZSAWa/9JbEZr9hBRoMGumVYKp+ET3fhhr209LuXFM/kUlUuiQf LsLV9OolI+h+V2qV6JJnzynTZK4YG9QOLPHEc7Z/0XokfZf/jEAzQbYaKzG/HXiJqo gJCaIT+gWBCVLE1Huu3k5wUHY4dPm0TiCWt8OWl0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726774AbfDJAqY (ORCPT ); Tue, 9 Apr 2019 20:46:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:34224 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726730AbfDJAqY (ORCPT ); Tue, 9 Apr 2019 20:46:24 -0400 Received: from sol.localdomain (c-24-5-143-220.hsd1.ca.comcast.net [24.5.143.220]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2C93D21741; Wed, 10 Apr 2019 00:46:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554857183; bh=oIWDtTvz1vibsjrk4J5eD/OHob32N5Dx/zh+H/G/qSc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=lccJJmT6YH02WpKrP8F/NlxpglOle6qD3Fgfh8RAnvyyX24TmkpldgqOIpqiN4qmz lmtLMmH7P+ogjgqVLAfse2NF2QIECO2Pg+X8tz/RsP62EJrY7dMzhaBEynAHvYWvv7 ok7UwxyQO+JFNJ50y5ylmDEa7Ks06ygK/tmNzStE= Date: Tue, 9 Apr 2019 17:45:54 -0700 From: Eric Biggers To: Al Viro Cc: linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Subject: Re: [PATCH] fscrypt: cache decrypted symlink target in ->i_link Message-ID: <20190410004553.GA2454@sol.localdomain> References: <20190409233544.156665-1-ebiggers@kernel.org> <20190410003346.GT2217@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190410003346.GT2217@ZenIV.linux.org.uk> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Apr 10, 2019 at 01:33:46AM +0100, Al Viro wrote: > On Tue, Apr 09, 2019 at 04:35:44PM -0700, Eric Biggers wrote: > > From: Eric Biggers > > > > Path lookups that traverse encrypted symlink(s) are very slow because > > each encrypted symlink needs to be decrypted each time it's followed. > > > > Make encrypted symlinks faster by caching the decrypted symlink target > > in ->i_link. The first call to ->get_link() sets it; later calls simply > > return it. ->symlink() also sets it when the symlink is created. > > > > When the inode's ->i_crypt_info is freed, ->i_link is freed too. > > > > Note: RCU-delayed freeing of ->i_link is not yet implemented. > > Therefore, for now even when ->i_link is set, path lookups must continue > > to drop out of RCU-walk mode when following an encrypted symlink. > > And how the devil would they continue to do that, if I might ask? > ->get_link() is *NOT* called if ->i_link is non-NULL, period. You're right, I didn't notice that ->get_link() isn't called when ->i_link is non-NULL. But that being the case, what's the point of simple_get_link()? - Eric