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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT 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 57024C10F11 for ; Thu, 11 Apr 2019 02:25:35 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 2395420818 for ; Thu, 11 Apr 2019 02:25:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="auZLnRiB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2395420818 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Ag/YwZ4yA9CPeOQOOR6ow4qglZtKg/jkzLoDpPyLHSI=; b=auZLnRiBBHy91T vIsNKTEMaARGWcKj6WuRDY7HqhI07FruLLYJXWbqXZtSmCbpDngpF8xBn0Auz2pRZm68tBg63hnej wqRFIjpGeGqElRoQp70Vo+eXWrbgD+TTAiGkOLBORwyU43+cdMot5ZFCvwgfRBBYfP2R/4VS8w4QY rIw8J3eKCooomPCg8X8ptH+dGlMJv6Nbrj22tz34ku+UZ2Mi6rYwWCVxt6idW4twIghHztA44ihFi gkpRhYrGSzJpzBBfDhTXIm/BzgLaQbU4Tg3uF6L99/klVl4N/nAP1Lz7lTBb3oT9Mn3slHbWQM41Z ylh9ahmExHA6skOe4uSQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hEPP5-0004Rp-Mj; Thu, 11 Apr 2019 02:25:27 +0000 Received: from zeniv.linux.org.uk ([195.92.253.2]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hEPOz-0004QN-Ha for linux-mtd@lists.infradead.org; Thu, 11 Apr 2019 02:25:24 +0000 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92 #3 (Red Hat Linux)) id 1hEPOt-0002JD-BR; Thu, 11 Apr 2019 02:25:15 +0000 Date: Thu, 11 Apr 2019 03:25:15 +0100 From: Al Viro To: Eric Biggers Subject: Re: [PATCH v2 1/2] vfs: use READ_ONCE() to access ->i_link Message-ID: <20190411022514.GC2217@ZenIV.linux.org.uk> References: <20190410202115.64501-1-ebiggers@kernel.org> <20190410202115.64501-2-ebiggers@kernel.org> <20190410210657.GA2217@ZenIV.linux.org.uk> <20190410231547.GC120258@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190410231547.GC120258@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190410_192521_584957_ACB95D9E X-CRM114-Status: GOOD ( 12.50 ) X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-fsdevel@vger.kernel.org, linux-fscrypt@vger.kernel.org, linux-ext4@vger.kernel.org, linux-mtd@lists.infradead.org, linux-f2fs-devel@lists.sourceforge.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org On Wed, Apr 10, 2019 at 04:15:48PM -0700, Eric Biggers wrote: > On Wed, Apr 10, 2019 at 10:06:57PM +0100, Al Viro wrote: > > On Wed, Apr 10, 2019 at 01:21:14PM -0700, Eric Biggers wrote: > > > From: Eric Biggers > > > > > > Use 'READ_ONCE(inode->i_link)' to explicitly support filesystems caching > > > the symlink target in ->i_link later if it was unavailable at iget() > > > time, or wasn't easily available. I'll be doing this in fscrypt, to > > > improve the performance of encrypted symlinks on ext4, f2fs, and ubifs. > > > > > > ->i_link will start NULL and may later be set to a non-NULL value by a > > > smp_store_release() or cmpxchg_release(). READ_ONCE() is needed on the > > > read side. smp_load_acquire() is unnecessary because only a data > > > dependency barrier is required. (Thanks to Al for pointing this out.) > > > > You've missed vfs_readlink()... > > How so? The patch already updates vfs_readlink(). Huh? Right you are - fsck knows how have I managed to misread that... Anyway, I can pick that READ_ONCE() patch through vfs.git if you wish, or it can go through your tree with my Acked-by - up to you... ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/