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 DC22DC10F25 for ; Fri, 6 Mar 2020 20:51:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ACDF2206CC for ; Fri, 6 Mar 2020 20:51:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=szeredi.hu header.i=@szeredi.hu header.b="btIso5bB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726833AbgCFUv0 (ORCPT ); Fri, 6 Mar 2020 15:51:26 -0500 Received: from mail-io1-f65.google.com ([209.85.166.65]:33232 "EHLO mail-io1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726307AbgCFUvZ (ORCPT ); Fri, 6 Mar 2020 15:51:25 -0500 Received: by mail-io1-f65.google.com with SMTP id r15so3460000iog.0 for ; Fri, 06 Mar 2020 12:51:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=szeredi.hu; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=yGLtF9/BkDRWldf7v6sxW1Van8tpD2gHUBIr/g2ZUWQ=; b=btIso5bBh9Rv1yNfjzkAnbfr2G9RML5beBupa0KwwDUB7Vp6++GaqpK9U+yZZ0xHKM ipSc/GpWSMvtp7BCt1SRYDgKseFvcYE6FRrC7IOt6u6eUm9kpmvEnLIf5X0Pj3+wk74Y jXqabBNwRqfd1bnlPa77rD0hXRB/4wM9p0ed8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=yGLtF9/BkDRWldf7v6sxW1Van8tpD2gHUBIr/g2ZUWQ=; b=F9Y0wmzP9mEmRQMAFIXHy8ZYcn14nAxuky0yeMlcDcHL2CdNiNbNtxirNlVIPEIjug 0oCMR2RrWMPkfQtNBJIJvnbDSU8r9slCgASMOpK2gzEan+hJ9ueEAX+MHQQUvm4nZwMQ hZwUHjaeMTCbFYkIuq9iipUYVFcXFycHJH8GhdloKMDOCBLHPRcVFQuUiJh3yZrWz+x2 fzfB6k5H/TEmM/pshL3RXUT5Tho/WXGnzRsJV/K6fzccTg0qFki0UZqgWNy10u8I4PEO AeJ0XgZ1JYd3O2IoH0xWq0qP1YlxBuezkA1trvr3DDNFNVAwCpdTvdAGNS8559M2O82q t69g== X-Gm-Message-State: ANhLgQ098SpbZODw+d5PiayRt29l6D012Dfl9ljk4zdxyvF5WqctQRaZ YlA/jqD2aVmiYRZeSoEX5271LRKBD0zM9qv/VklBCw== X-Google-Smtp-Source: ADFU+vu/g23Eny9Hui/8pPFHbWtFGWqaVVE0ZerOiGOSF60dyc66F/0qyRGZhlaMt49a1aoSPVziVIZ4YVAEwD0pspQ= X-Received: by 2002:a02:70cc:: with SMTP id f195mr4679379jac.78.1583527883788; Fri, 06 Mar 2020 12:51:23 -0800 (PST) MIME-Version: 1.0 References: <107666.1582907766@warthog.procyon.org.uk> <0403cda7345e34c800eec8e2870a1917a8c07e5c.camel@themaw.net> <20200306162549.GA28467@miu.piliscsaba.redhat.com> <20200306194322.GY23230@ZenIV.linux.org.uk> <20200306195823.GZ23230@ZenIV.linux.org.uk> <20200306200522.GA23230@ZenIV.linux.org.uk> <20200306203705.GB23230@ZenIV.linux.org.uk> <20200306203844.GC23230@ZenIV.linux.org.uk> <20200306204523.GD23230@ZenIV.linux.org.uk> In-Reply-To: <20200306204523.GD23230@ZenIV.linux.org.uk> From: Miklos Szeredi Date: Fri, 6 Mar 2020 21:51:12 +0100 Message-ID: Subject: Re: [PATCH 00/17] VFS: Filesystem information and notifications [ver #17] To: Al Viro Cc: Ian Kent , David Howells , Christian Brauner , James Bottomley , Steven Whitehouse , Miklos Szeredi , Christian Brauner , Jann Horn , "Darrick J. Wong" , Linux API , linux-fsdevel , lkml , Greg Kroah-Hartman Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Mar 6, 2020 at 9:45 PM Al Viro wrote: > > On Fri, Mar 06, 2020 at 08:38:44PM +0000, Al Viro wrote: > > On Fri, Mar 06, 2020 at 08:37:05PM +0000, Al Viro wrote: > > > > > You are misreading mntput_no_expire(), BTW - your get_mount() can > > > bloody well race with umount(2), hitting the moment when we are done > > > figuring out whether it's busy but hadn't cleaned ->mnt_ns (let alone > > > set MNT_DOOMED) yet. If somebody calls umount(2) on a filesystem that > > > is not mounted anywhere else, they are not supposed to see the sucker > > > return 0 until the filesystem is shut down. You break that. Ah, good point. > > > > While we are at it, d_alloc_parallel() requires i_rwsem on parent held > > at least shared. Okay. > Egads... Let me see if I got it right - you are providing procfs symlinks > to objects on the internal mount of that thing. And those objects happen > to be directories, so one can get to their parent that way. Or am I misreading > that thing? Yes. Thanks, Miklos