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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 546CDC77B71 for ; Tue, 25 Apr 2023 13:23:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234007AbjDYNXW (ORCPT ); Tue, 25 Apr 2023 09:23:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51096 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233967AbjDYNXV (ORCPT ); Tue, 25 Apr 2023 09:23:21 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [IPv6:2001:67c:2178:6::1d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D882113C1B; Tue, 25 Apr 2023 06:23:17 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 74FB91FD9D; Tue, 25 Apr 2023 13:23:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1682428996; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=q2T/Y7qFdCUy3re4ctXa9sRrn9+mZ7IugqZ9aq6o34k=; b=H5RfPmr5xbyO42qx+ZpGkRUj4c5qyh3489DrJZCn0bCZCHarr9ITUocACe2p9hpNO4DjSS I3z5Mo9Scj2JMheTyoFt4x5R1/Qn79qJ3eUzSMfYiOmEpEXjQi1GRNYfGXNs0dZcIA1kSj Z6PSBP3KAuGFl2cD/TbSR4YODdQbzwc= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1682428996; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=q2T/Y7qFdCUy3re4ctXa9sRrn9+mZ7IugqZ9aq6o34k=; b=3CbBzZyWb+srmnqcSy2+VdX9IAWZmiyyj1hNABq5DBj/WsGr2Y+J12K9Mqh+LOIqmTzs3m dRxsR5GpIV4WdPBg== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 6633713466; Tue, 25 Apr 2023 13:23:16 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id Jw3kGETUR2S8EwAAMHmgww (envelope-from ); Tue, 25 Apr 2023 13:23:16 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id EE3D9A0729; Tue, 25 Apr 2023 15:23:15 +0200 (CEST) Date: Tue, 25 Apr 2023 15:23:15 +0200 From: Jan Kara To: Shiyang Ruan Cc: Jan Kara , djwong@kernel.org, Luis Chamberlain , linux-fsdevel@vger.kernel.org, nvdimm@lists.linux.dev, linux-xfs@vger.kernel.org, linux-mm@kvack.org, dan.j.williams@intel.com, willy@infradead.org, akpm@linux-foundation.org Subject: Re: [RFC PATCH v11.1 2/2] mm, pmem, xfs: Introduce MF_MEM_REMOVE for unbind Message-ID: <20230425132315.u5ocvbneeqzzbifl@quack3> References: <1679996506-2-3-git-send-email-ruansy.fnst@fujitsu.com> <1681296735-2-1-git-send-email-ruansy.fnst@fujitsu.com> <0a53ee26-5771-0808-ccdc-d1739c9dacac@fujitsu.com> <20230420120956.cdxcwojckiw36kfg@quack3> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue 25-04-23 20:47:35, Shiyang Ruan wrote: > > > 在 2023/4/20 20:09, Jan Kara 写道: > > On Thu 20-04-23 10:07:39, Shiyang Ruan wrote: > > > 在 2023/4/12 18:52, Shiyang Ruan 写道: > > > > This is a RFC HOTFIX. > > > > > > > > This hotfix adds a exclusive forzen state to make sure any others won't > > > > thaw the fs during xfs_dax_notify_failure(): > > > > > > > > #define SB_FREEZE_EXCLUSIVE (SB_FREEZE_COMPLETE + 2) > > > > Using +2 here is because Darrick's patch[0] is using +1. So, should we > > > > make these definitions global? > > > > > > > > Another thing I can't make up my mind is: when another freezer has freeze > > > > the fs, should we wait unitl it finish, or print a warning in dmesg and > > > > return -EBUSY? > > > > > > > > Since there are at least 2 places needs exclusive forzen state, I think > > > > we can refactor helper functions of freeze/thaw for them. e.g. > > > > int freeze_super_exclusive(struct super_block *sb, int frozen); > > > > int thaw_super_exclusive(struct super_block *sb, int frozen); > > > > > > > > [0] https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux.git/commit/?h=repair-fscounters&id=c3a0d1de4d54ffb565dbc7092dfe1fb851940669 > > > > I'm OK with the idea of new freeze state that does not allow userspace to > > thaw the filesystem. But I don't really like the guts of filesystem > > freezing being replicated inside XFS. It is bad enough that they are > > replicated in [0], replicating them *once more* in another XFS file shows > > we are definitely doing something wrong. And Luis will need yet another > > incantation of the exlusive freeze for suspend-to-disk. So please guys get > > together and reorganize the generic freezing code so that it supports > > exclusive freeze (for in-kernel users) and works for your usecases instead > > of replicating it inside XFS... > > I agree that too much replicating code is not good. It's necessary to > create a generic exclusive freeze/thaw for all users. But for me, I don't > have the confidence to do it well, because it requires good design and code > changes will involve other filesystems. It's diffcult. > > However, I hope to be able to make progress on this unbind feature. Thus, I > tend to refactor a common helper function for xfs first, and update the code > later when the generic freeze is done. I think Darrick was thinking about working on a proper generic interface. So please coordinate with him. Honza -- Jan Kara SUSE Labs, CR