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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_MED,USER_IN_DEF_DKIM_WL 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 4F8D2C46460 for ; Tue, 28 May 2019 23:24:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 266F721670 for ; Tue, 28 May 2019 23:24:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Ot3EWkd2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726969AbfE1XYE (ORCPT ); Tue, 28 May 2019 19:24:04 -0400 Received: from mail-ot1-f65.google.com ([209.85.210.65]:38564 "EHLO mail-ot1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726963AbfE1XYD (ORCPT ); Tue, 28 May 2019 19:24:03 -0400 Received: by mail-ot1-f65.google.com with SMTP id s19so168409otq.5 for ; Tue, 28 May 2019 16:24:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=HGPN9OjlN0u2vkYT7lUEXn5/y2a9ZsC+Dfozs38xwo0=; b=Ot3EWkd25DfNtyqQZi2lKoCMywsWj1GEkyVsamx8IhpKmMYoQlNVtFXDsN5kzZ6ztV G0G4l+Yn9BT/91zveLip+MqoiQ9WY7KdLEeUnxKqsGaf/8a6P6TCdXsDzggmJbd8BC7j j7g/1ER+6QZ5ydhZ3Bf+DMekuCVU7XQ2krnuSQI+4HCJgoVYtDwKLQjR3UkiqRBl2ZBC Hbgfr4g8WcFCgwSmqfiyN+oPogiE52ZKR9MwXWkiESYTJsOEtnnzFKKAjkloisXxqBPE +CTyleolaoiiIlj62zgtnI49WL88oeZM7ei1tnil/DaLguKbl4ERfII14rmEY0DmU5Lo 55/w== 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=HGPN9OjlN0u2vkYT7lUEXn5/y2a9ZsC+Dfozs38xwo0=; b=rf8CPQyH0XlvRBV1I8toDro7VuyvwTp0CPpf0NjsgreCdAxqzVqulFfm98PpgT0PuH eMTD6Bd+K3SRmGcnEzCvKyLYpYogmjvq/xvA3wprxlDbk/TfLYishmSgxM6SfYRyzSUb 1PE8TkWdm+bHvWGC+RjyfzZBpfmDNgmPSj1xwtHnLiv5oQFGTp0bZzk6WePU3Q5AU/8e 5SP4jd5C8PDgnuk+B5+7FeOA+wFL3gtGlPBykeQqeUHs/R7E1qUja27EpGcKZKj5VkdT Cgv4s0bQW9GjzTy8wGCrrQhWUzR1oh1mN2N8GB++4S3TvSaAWzP1uxsjgSLFK34ZZc70 +mkQ== X-Gm-Message-State: APjAAAV6DSuUcn6zg3FCC9sMrR2Tudc9tM37Cfla8Wn2ViNqIz7DAgKl eigF1KnaYvWLbho+0sT3DYCLRcxePJeLOKxF3p25SA== X-Google-Smtp-Source: APXvYqzRVCXeGxin0Tw+MDHx9N4J9nIhwON+HiBvCivgZkw6Vu0lhpKmb1+NRC/UKwUe3iqj0TpzPBIsvDgNEbU7wmE= X-Received: by 2002:a9d:7f8b:: with SMTP id t11mr5793otp.110.1559085842981; Tue, 28 May 2019 16:24:02 -0700 (PDT) MIME-Version: 1.0 References: <155905930702.7587.7100265859075976147.stgit@warthog.procyon.org.uk> <155905933492.7587.6968545866041839538.stgit@warthog.procyon.org.uk> <10418.1559084686@warthog.procyon.org.uk> In-Reply-To: <10418.1559084686@warthog.procyon.org.uk> From: Jann Horn Date: Wed, 29 May 2019 01:23:36 +0200 Message-ID: Subject: Re: [PATCH 3/7] vfs: Add a mount-notification facility To: David Howells Cc: Al Viro , raven@themaw.net, linux-fsdevel , Linux API , linux-block@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module , kernel list 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 Wed, May 29, 2019 at 1:04 AM David Howells wrote: > Jann Horn wrote: > > It might make sense to redesign this stuff so that watches don't hold > > references on the object being watched. > > I explicitly made it hold a reference so that if you place a watch on an > automounted mount it stops it from expiring. > > Further, if I create a watch on something, *should* it be unmountable, just as > if I had a file open there or had chdir'd into there? I don't really know. I guess it depends on how it's being used? If someone decides to e.g. make a file browser that installs watches for a bunch of mountpoints for some fancy sidebar showing the device mounts on the system, or something like that, that probably shouldn't inhibit unmounting... I don't know if that's a realistic use case.