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=-0.8 required=3.0 tests=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 05B9AC2D0DB for ; Mon, 20 Jan 2020 15:11:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CC70722314 for ; Mon, 20 Jan 2020 15:11:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chrisdown.name header.i=@chrisdown.name header.b="MlG60/Pj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729080AbgATPLY (ORCPT ); Mon, 20 Jan 2020 10:11:24 -0500 Received: from mail-wr1-f65.google.com ([209.85.221.65]:33663 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726642AbgATPLV (ORCPT ); Mon, 20 Jan 2020 10:11:21 -0500 Received: by mail-wr1-f65.google.com with SMTP id b6so29996384wrq.0 for ; Mon, 20 Jan 2020 07:11:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chrisdown.name; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=fpFQ1fEPd0yd6/Fy18DraiEyPGTTtIbb9sRJOIkGs+o=; b=MlG60/Pjxo9rE2vXGmlDoYw5RKWpmvGa+soqFJ7dW2eRzq+T9rENvcZmWbcZl6uzwh z41+vpmQZ3IvNUtv0zeGZ1Beb9xhC7Hlphqnrho0nhPivDtyewP1yOx/zDB2UjoMUl5U LT68YwyROGqrbxDvcCE7zmcicSS1FZ193iqTQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=fpFQ1fEPd0yd6/Fy18DraiEyPGTTtIbb9sRJOIkGs+o=; b=fpacaQ55ucR8eqdbcLWhnN1kgz4z8QaQh8oro87dvYsrls1bFAJoiUPrG9dYFJmsjl pFo9ICBEYN7viHezmwMTofQIVGobztBPOp+NRKkrzv1Bt+xC6DGtFIt3CLwwb183jXtP NrrlQfKraehvR1kbrFaDFTf+eBfYN9bWGEzYpHN2J/zKlczYfyKzfnzAcZL6SD6rlLDl Zeyx/5tTmwypKaE8LBAFkUt1cGasUiE1cZ/NL0g0NoQqxfhsexwl+xvjcGjV/aEc0w/a jcy8d+HepvzxJX3tCZ8xwE7joCf4257WqzflirfRFCeJNc0YDCZApyqRHrDuM9CK7GRx eawA== X-Gm-Message-State: APjAAAVxU3EaaR2At80gfZCKZtK8Th9/My/0cmPblJvLy7Xbz5iQ83OI PXkj93XFTkAO3QY7EP272Now0A== X-Google-Smtp-Source: APXvYqyWKGmCoy+9bvGRA2RniQZCgf4tZzcO38mWdEPr54brhtY82T71lmAyTZO6n140BPQ4R1vXQw== X-Received: by 2002:adf:ea05:: with SMTP id q5mr15043wrm.48.1579533079122; Mon, 20 Jan 2020 07:11:19 -0800 (PST) Received: from localhost ([2620:10d:c092:180::1:251f]) by smtp.gmail.com with ESMTPSA id q15sm47977328wrr.11.2020.01.20.07.11.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Jan 2020 07:11:18 -0800 (PST) Date: Mon, 20 Jan 2020 15:11:17 +0000 From: Chris Down To: Hugh Dickins Cc: Dave Chinner , Chris Mason , Amir Goldstein , Linux MM , Andrew Morton , Al Viro , Matthew Wilcox , Jeff Layton , Johannes Weiner , Tejun Heo , Mikael Magnusson , linux-fsdevel , linux-kernel , Kernel Team Subject: Re: [PATCH v5 2/2] tmpfs: Support 64-bit inums per-sb Message-ID: <20200120151117.GA81113@chrisdown.name> References: <20200107001643.GA485121@chrisdown.name> <20200107003944.GN23195@dread.disaster.area> <20200107210715.GQ23195@dread.disaster.area> <4E9DF932-C46C-4331-B88D-6928D63B8267@fb.com> <20200110164503.GA1697@chrisdown.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hi Hugh, Sorry this response took so long, I had some non-work issues that took a lot of time last week. Hugh Dickins writes: >On Fri, 10 Jan 2020, Chris Down wrote: >> Hugh Dickins writes: >> > Dave, Amir, Chris, many thanks for the info you've filled in - >> > and absolutely no need to run any scan on your fleet for this, >> > I think we can be confident that even if fb had some 15-year-old tool >> > in use on its fleet of 2GB-file filesystems, it would not be the one >> > to insist on a kernel revert of 64-bit tmpfs inos. >> > >> > The picture looks clear now: while ChrisD does need to hold on to his >> > config option and inode32/inode64 mount option patch, it is much better >> > left out of the kernel until (very unlikely) proved necessary. >> >> Based on Mikael's comment above about Steam binaries, and the lack of >> likelihood that they can be rebuilt, I'm inclined to still keep inode{64,32}, >> but make legacy behaviour require explicit opt-in. That is: >> >> - Default it to inode64 >> - Remove the Kconfig option >> - Only print it as an option if tmpfs was explicitly mounted with inode32 >> >> The reason I suggest keeping this is that I'm mildly concerned that the kind >> of users who might be impacted by this change due to 32-bit _FILE_OFFSET_BITS >> -- like the not-too-uncommon case that Mikael brings up -- seem unlikely to >> be the kind of people that would find it in an rc. > >Okay. None of us are thrilled with it, but I agree that >Mikael's observation should override our developer's preference. > >So the "inode64" option will be accepted but redundant on mounting, >but exists for use as a remount option after mounting or remounting >with "inode32": allowing the admin to switch temporarily to mask off >the high ino bits with "inode32" when needing to run a limited binary. > >Documentation and commit message to alert Andrew and Linus and distros >that we are risking some breakage with this, but supplying the antidote >(not breakage of any distros themselves, no doubt they're all good; >but breakage of what some users might run on them). Sounds good. >> >> Other than that, the first patch could be similar to how it is now, >> incorporating Hugh's improvements to the first patch to put everything under >> the same stat_lock in shmem_reserve_inode. > >So, I persuaded Amir to the other aspects my version, but did not >persuade you? Well, I can live with that (or if not, can send mods >on top of yours): but please read again why I was uncomfortable with >yours, to check that you still prefer it (I agree that your patch is >simpler, and none of my discomfort decisive). Hmm, which bit were you thinking of? The lack of batching, shmem_encode_fh(), or the fact that nr_inodes can now be 0 on non-internal mounts? For batching, I'm neutral. I'm happy to use the approach from your patch and integrate it (and credit you, of course). For shmem_encode_fh, I'm not totally sure I understand the concern, if that's what you mean. For nr_inodes, I agree that intentional or unintentional, we should at least handle this case for now and can adjust later if the behaviour changes. Thanks again, Chris