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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 23C1EC48BCF for ; Sun, 13 Jun 2021 01:57:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F403B61105 for ; Sun, 13 Jun 2021 01:57:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231626AbhFMB7X (ORCPT ); Sat, 12 Jun 2021 21:59:23 -0400 Received: from wnew3-smtp.messagingengine.com ([64.147.123.17]:49119 "EHLO wnew3-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229985AbhFMB7V (ORCPT ); Sat, 12 Jun 2021 21:59:21 -0400 Received: from compute5.internal (compute5.nyi.internal [10.202.2.45]) by mailnew.west.internal (Postfix) with ESMTP id 3D3644D0; Sat, 12 Jun 2021 21:57:20 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute5.internal (MEProxy); Sat, 12 Jun 2021 21:57:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=themaw.net; h= message-id:subject:from:to:cc:date:in-reply-to:references :content-type:mime-version:content-transfer-encoding; s=fm3; bh= Uom0PmQvH9twYv18/8DY+8ughWYvRfkhlllMXqiZF9U=; b=OVUqdN8gDqbMKH0g IlIvGy0J1ex1TF/hXzLNtxTfLsNa4rSJkveblDtecrR9zYUHKgfiZi2GLyQz8khL yd881w21Mb6sfk6IE/KYPowxeh4lqcc+oROudNGRpZjeAHG3I0SyoGaRbaYjVC0q 50SaI6zRhbg7ILd3am82bbrnfAmCP74Xb/TgwwMR4b+6jE3YHoxN4AMAHelbDLeU vOnv8/qo1br9kMoxZ/A2S15L61yGXhXnxM1HS0mgpeDsYPJcGb+7vXwK4IKx2Nk7 x9wbNylHNp2CFyoBhyjtx556ET2k7pe9Gw5AwTnf51bA26pivVzgN1pgcIIUIqUa e8wpYw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:in-reply-to:message-id:mime-version:references :subject:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm3; bh=Uom0PmQvH9twYv18/8DY+8ughWYvRfkhlllMXqiZF 9U=; b=HNfZq2tlph76QK1wHJxNX6QbI4L3TFJBIjObPCmEcRhDEw5jUGAi/vz7y DkRRI4+vEj6TviS+s5KeBwcaN65Bl9bAUwQvebCw7IdodA47vAl7866a1bXizA2M p2JKl5jgV03coqHIecWwZx4qYUbTDRupWx+8skwYbR93eX/Y5JAlXloKUSYq9bv/ lB2C6LRi4MYTyLgs9V1KAfYeMT6YM/wFM+8dcXUEJFtQXwurUKzwtTu4zoXLwxBw RewV03ncFGxnl7QzafuquIQ6NX2ON35qZQ/SG/sVRVgu3GHqKJW9r2yhZfb9/3CJ qEh1uExBTKXSsas6ohBXJEpB6xe6g== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduledrfedvuddggeejucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepkffuhffvffgjfhgtfggggfesthekredttderjeenucfhrhhomhepkfgrnhcu mfgvnhhtuceorhgrvhgvnhesthhhvghmrgifrdhnvghtqeenucggtffrrghtthgvrhhnpe fgleelkeetheelgeehueejueduhfeufffgleehgfevtdehhffhhffhtddugfefheenucev lhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpehrrghvvghnse hthhgvmhgrfidrnhgvth X-ME-Proxy: Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sat, 12 Jun 2021 21:57:14 -0400 (EDT) Message-ID: <8304e49310b16b865868982802bd2344d076c974.camel@themaw.net> Subject: Re: [PATCH v6 3/7] kernfs: use VFS negative dentry caching From: Ian Kent To: Al Viro Cc: Greg Kroah-Hartman , Tejun Heo , Eric Sandeen , Fox Chen , Brice Goglin , Rick Lindsley , David Howells , Miklos Szeredi , Marcelo Tosatti , "Eric W. Biederman" , Carlos Maiolino , linux-fsdevel , Kernel Mailing List Date: Sun, 13 Jun 2021 09:57:10 +0800 In-Reply-To: References: <162322846765.361452.17051755721944717990.stgit@web.messagingengine.com> <162322862726.361452.10114120072438540655.stgit@web.messagingengine.com> <2ee74cbed729d66a38a5c7de9c4608d02fb89f26.camel@themaw.net> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.38.4 (3.38.4-1.fc33) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2021-06-12 at 01:51 +0000, Al Viro wrote: > On Sat, Jun 12, 2021 at 09:08:05AM +0800, Ian Kent wrote: > > > But if I change to take the read lock to ensure there's no > > operation > > in progress for the revision check I would need the dget_parent(), > > yes? > > WTF for?  ->d_parent can change *ONLY* when ->d_lock is held on all > dentries involved (including old and new parents). Understood, thanks. > > And it very definitely does *not* change for negative dentries.  I > mean, > look at the very beginning of __d_move().