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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 78621C48BE5 for ; Fri, 11 Jun 2021 12:56:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B8F961029 for ; Fri, 11 Jun 2021 12:56:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231715AbhFKM6d (ORCPT ); Fri, 11 Jun 2021 08:58:33 -0400 Received: from wnew3-smtp.messagingengine.com ([64.147.123.17]:43523 "EHLO wnew3-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231482AbhFKM6a (ORCPT ); Fri, 11 Jun 2021 08:58:30 -0400 Received: from compute2.internal (compute2.nyi.internal [10.202.2.42]) by mailnew.west.internal (Postfix) with ESMTP id 61F6C1980; Fri, 11 Jun 2021 08:56:28 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute2.internal (MEProxy); Fri, 11 Jun 2021 08:56:29 -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= iW4ZE/BB6PBmS5q7Ee0NyNuhpgtw/+D17L4kdaX9rXU=; b=QJxIZIC4SBtkNphu PvayLa5vSlo4/BTtnda6Z6oE10JTUXdyRr19mj9eNy45JzLdvLnAi5nozX0VzIBl KmuAqf30pHP9s/EbtrxsFmzGcMBAIoBwV0lIB9mwOV4suhr25ulqHs7ZMyhovcNF ShuLnovIefDF6+50uzy9yzsOWYYkA40OkxetniAJFrKWluvxIRVd/OYCBkKvShiC slPqPG2DQboOVmoWwTx6tS/Z/O+KGeJFNbUso4n2q0gRZ3NELYtIAq8J4ai3n/H2 XFjbOvfS/D06b29sof5jzfaN26IiUchwx9lmOBv4BeC4cyk7HFbx2UyeEAHHImHS ZNpfQg== 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=iW4ZE/BB6PBmS5q7Ee0NyNuhpgtw/+D17L4kdaX9r XU=; b=NAWmrgbh+gyOGzG9gi/2WGKBjC84htMyoaPIfhKjRqomhdeErfWGpOA80 w5dO2ieyUusayl9SpUlyI20cseCzf19XdHnEAjy3gTrNGsWZX+xbPv9yUoFWPO9a 1xsy6rA2k1yKLIx9/gyzc2yylyiEPxclFv6dhOCjnZFO3iwBQdJtCOGrBuH7yXbi 0Ba6bxiyAoSIXNIeuZIC1uMVyjFAbUPTc6iJLcRsREhtcWAC1JxVnbv0rw5xo6Mi BJTCzo3Cj0Ay0+w+CcRxnPMr2a/oC75SZZf82024ZdtwqPQCQ/j0+ngUi1GOl27A rnaIMwcoB2DIVzzR2Y/rXlehiUMNw== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduledrfedujedgheejucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepkffuhffvffgjfhgtfggggfesthekredttderjeenucfhrhhomhepkfgrnhcu mfgvnhhtuceorhgrvhgvnhesthhhvghmrgifrdhnvghtqeenucggtffrrghtthgvrhhnpe fgleelkeetheelgeehueejueduhfeufffgleehgfevtdehhffhhffhtddugfefheenucev lhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpehrrghvvghnse hthhgvmhgrfidrnhgvth X-ME-Proxy: Received: by mail.messagingengine.com (Postfix) with ESMTPA; Fri, 11 Jun 2021 08:56:22 -0400 (EDT) Message-ID: <03f6e366fb4ebb56b15541d53eda461a55d3d38e.camel@themaw.net> Subject: Re: [PATCH v6 2/7] kernfs: add a revision to identify directory node changes From: Ian Kent To: Miklos Szeredi Cc: Greg Kroah-Hartman , Tejun Heo , Eric Sandeen , Fox Chen , Brice Goglin , Al Viro , Rick Lindsley , David Howells , Marcelo Tosatti , "Eric W. Biederman" , Carlos Maiolino , linux-fsdevel , Kernel Mailing List Date: Fri, 11 Jun 2021 20:56:18 +0800 In-Reply-To: References: <162322846765.361452.17051755721944717990.stgit@web.messagingengine.com> <162322859985.361452.14110524195807923374.stgit@web.messagingengine.com> 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 Fri, 2021-06-11 at 14:49 +0200, Miklos Szeredi wrote: > On Wed, 9 Jun 2021 at 10:50, Ian Kent wrote: > > > > Add a revision counter to kernfs directory nodes so it can be used > > to detect if a directory node has changed during negative dentry > > revalidation. > > > > There's an assumption that sizeof(unsigned long) <= sizeof(pointer) > > on all architectures and as far as I know that assumption holds. > > > > So adding a revision counter to the struct kernfs_elem_dir variant > > of > > the kernfs_node type union won't increase the size of the > > kernfs_node > > struct. This is because struct kernfs_elem_dir is at least > > sizeof(pointer) smaller than the largest union variant. It's > > tempting > > to make the revision counter a u64 but that would increase the size > > of > > kernfs_node on archs where sizeof(pointer) is smaller than the > > revision > > counter. > > > > Signed-off-by: Ian Kent > > --- > >  fs/kernfs/dir.c             |    2 ++ > >  fs/kernfs/kernfs-internal.h |   23 +++++++++++++++++++++++ > >  include/linux/kernfs.h      |    5 +++++ > >  3 files changed, 30 insertions(+) > > > > diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c > > index 33166ec90a112..b3d1bc0f317d0 100644 > > --- a/fs/kernfs/dir.c > > +++ b/fs/kernfs/dir.c > > @@ -372,6 +372,7 @@ static int kernfs_link_sibling(struct > > kernfs_node *kn) > >         /* successfully added, account subdir number */ > >         if (kernfs_type(kn) == KERNFS_DIR) > >                 kn->parent->dir.subdirs++; > > +       kernfs_inc_rev(kn->parent); > > > >         return 0; > >  } > > @@ -394,6 +395,7 @@ static bool kernfs_unlink_sibling(struct > > kernfs_node *kn) > > > >         if (kernfs_type(kn) == KERNFS_DIR) > >                 kn->parent->dir.subdirs--; > > +       kernfs_inc_rev(kn->parent); > > > >         rb_erase(&kn->rb, &kn->parent->dir.children); > >         RB_CLEAR_NODE(&kn->rb); > > diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs- > > internal.h > > index ccc3b44f6306f..b4e7579e04799 100644 > > --- a/fs/kernfs/kernfs-internal.h > > +++ b/fs/kernfs/kernfs-internal.h > > @@ -81,6 +81,29 @@ static inline struct kernfs_node > > *kernfs_dentry_node(struct dentry *dentry) > >         return d_inode(dentry)->i_private; > >  } > > > > +static inline void kernfs_set_rev(struct kernfs_node *kn, > > +                                 struct dentry *dentry) > > +{ > > +       if (kernfs_type(kn) == KERNFS_DIR) > > +               dentry->d_time = kn->dir.rev; > > +} > > + > > +static inline void kernfs_inc_rev(struct kernfs_node *kn) > > +{ > > +       if (kernfs_type(kn) == KERNFS_DIR) > > +               kn->dir.rev++; > > +} > > + > > +static inline bool kernfs_dir_changed(struct kernfs_node *kn, > > +                                     struct dentry *dentry) > > +{ > > +       if (kernfs_type(kn) == KERNFS_DIR) { > > Aren't these always be called on a KERNFS_DIR node? Yes they are. > > You could just reduce that to a WARN_ON, or remove the conditions > altogether then. I was tempted to not use the check, a WARN_ON sounds better than removing the check, I'll do that in a v7. Thanks Ian