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 B0E87C54EE9 for ; Tue, 13 Sep 2022 23:19:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229791AbiIMXT4 (ORCPT ); Tue, 13 Sep 2022 19:19:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34926 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229760AbiIMXTy (ORCPT ); Tue, 13 Sep 2022 19:19:54 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4318F186F2; Tue, 13 Sep 2022 16:19:53 -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 741A35C801; Tue, 13 Sep 2022 23:19:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1663111191; 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=1RlEFFdnbelVuFieKtPjIj+HKLf20F8SzyjGZ1aWdx4=; b=X9dQ1LYCcbxZz/h81Ze848AQlRqUlk2DBvX6vue+qjpMnhib9Hf1fr6QQ6ijSFa8W/cfV1 0nv6fBSU0w7Rxhanf8Q3ff++rFUaMccSy2W2WV45ScDdlnmLbD4Gf1XQVkWgTwEeNqGPq4 z4R860kGqnuKVIuIkfcYg0yQfn0/OpY= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1663111191; 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=1RlEFFdnbelVuFieKtPjIj+HKLf20F8SzyjGZ1aWdx4=; b=k7J0/dOeQK2ZeGErc6uewU0Y1p8Y5nmjHT1K1/vkJnV2/sBK47PCFpKFhnpwoqQ/Bptpkk jcnzrW221lNGvpBw== 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 6097513AB5; Tue, 13 Sep 2022 23:19:44 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id NpWqBhAQIWPwZAAAMHmgww (envelope-from ); Tue, 13 Sep 2022 23:19:44 +0000 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit MIME-Version: 1.0 From: "NeilBrown" To: "J. Bruce Fields" Cc: "Dave Chinner" , "Jeff Layton" , "Theodore Ts'o" , "Jan Kara" , adilger.kernel@dilger.ca, djwong@kernel.org, trondmy@hammerspace.com, viro@zeniv.linux.org.uk, zohar@linux.ibm.com, xiubli@redhat.com, chuck.lever@oracle.com, lczerner@redhat.com, brauner@kernel.org, fweimer@redhat.com, linux-man@vger.kernel.org, linux-api@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, ceph-devel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-nfs@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [man-pages RFC PATCH v4] statx, inode: document the new STATX_INO_VERSION field In-reply-to: <20220913190226.GA11958@fieldses.org> References: <20220908155605.GD8951@fieldses.org>, <9e06c506fd6b3e3118da0ec24276e85ea3ee45a1.camel@kernel.org>, <20220908182252.GA18939@fieldses.org>, <44efe219dbf511492b21a653905448d43d0f3363.camel@kernel.org>, <20220909154506.GB5674@fieldses.org>, <125df688dbebaf06478b0911e76e228e910b04b3.camel@kernel.org>, <20220910145600.GA347@fieldses.org>, <9eaed9a47d1aef11fee95f0079e302bc776bc7ff.camel@kernel.org>, <20220913004146.GD3600936@dread.disaster.area>, <166303374350.30452.17386582960615006566@noble.neil.brown.name>, <20220913190226.GA11958@fieldses.org> Date: Wed, 14 Sep 2022 09:19:22 +1000 Message-id: <166311116291.20483.960025733349761945@noble.neil.brown.name> Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Wed, 14 Sep 2022, J. Bruce Fields wrote: > On Tue, Sep 13, 2022 at 11:49:03AM +1000, NeilBrown wrote: > > Invalidating the client cache on EVERY unmount/mount could impose > > unnecessary cost. Imagine a client that caches a lot of data (several > > large files) from a server which is expected to fail-over from one > > cluster node to another from time to time. Adding extra delays to a > > fail-over is not likely to be well received. > > > > I don't *know* this cost would be unacceptable, and I *would* like to > > leave it to the filesystem to decide how to manage its own i_version > > values. So maybe XFS can use the LSN for a salt. If people notice the > > extra cost, they can complain. > > I'd expect complaints. > > NFS is actually even worse than this: it allows clients to reacquire > file locks across server restart and unmount/remount, even though > obviously the kernel will do nothing to prevent someone else from > locking (or modifying) the file in between. I don't understand this comment. You seem to be implying that changing the i_version during a server restart would stop a client from reclaiming locks. Is that correct? I would have thought that the client would largely ignore i_version while it has a lock or open or delegation, as these tend to imply some degree of exclusive access ("open" being least exclusive). Thanks, NeilBrown > > Administrators are just supposed to know not to allow other applications > access to the filesystem until nfsd's started. It's always been this > way. > > You can imagine all sorts of measures to prevent that, and if anyone > wants to work on ways to prevent people from shooting themselves in the > foot here, great. > > Just taking away the ability to cache or lock across reboots wouldn't > make people happy, though.... > > --b. >