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 6998AECAAD5 for ; Mon, 12 Sep 2022 13:51:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229759AbiILNve (ORCPT ); Mon, 12 Sep 2022 09:51:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42146 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229502AbiILNvc (ORCPT ); Mon, 12 Sep 2022 09:51:32 -0400 Received: from fieldses.org (fieldses.org [IPv6:2600:3c00:e000:2f7::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1C334183B5; Mon, 12 Sep 2022 06:51:32 -0700 (PDT) Received: by fieldses.org (Postfix, from userid 2815) id 823D96033; Mon, 12 Sep 2022 09:51:31 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org 823D96033 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fieldses.org; s=default; t=1662990691; bh=BCcOHKvxAW1IzfNYZs7R5fcMpz0xyKVDSP5+bCNB2vY=; h=Date:To:Cc:Subject:References:In-Reply-To:From:From; b=BNivq+2dffYxGwFrbIbzNTMDyqxbKJBuwJ19P++KVeq84Zmv4FAGo+4AqY/2H5tBR zQQsDppJzaNDjrg6QGdsJ/T4xX4EyK7b/b6uGm9Z0aIvcMsO6amE/CIiqSaxGxLuso DbeTGFEV6tEVIqhhEH6eBM3dKpln+kjwpt1atzn8= Date: Mon, 12 Sep 2022 09:51:31 -0400 To: Jeff Layton Cc: Florian Weimer , Theodore Ts'o , Jan Kara , NeilBrown , adilger.kernel@dilger.ca, djwong@kernel.org, david@fromorbit.com, 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, 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 Message-ID: <20220912135131.GC9304@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> <87a67423la.fsf@oldenburg.str.redhat.com> <7c71050e139a479e08ab7cf95e9e47da19a30687.camel@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7c71050e139a479e08ab7cf95e9e47da19a30687.camel@kernel.org> User-Agent: Mutt/1.5.21 (2010-09-15) From: bfields@fieldses.org (J. Bruce Fields) Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Mon, Sep 12, 2022 at 08:55:04AM -0400, Jeff Layton wrote: > Because of the "seen" flag, we have a 63 bit counter to play with. Could > we use a similar scheme to the one we use to handle when "jiffies" > wraps? Assume that we'd never compare two values that were more than > 2^62 apart? We could add i_version_before/i_version_after macros to make > it simple to handle this. As far as I recall the protocol just assumes it can never wrap. I guess you could add a new change_attr_type that works the way you describe. But without some new protocol clients aren't going to know what to do with a change attribute that wraps. I think this just needs to be designed so that wrapping is impossible in any realistic scenario. I feel like that's doable? If we feel we have to catch that case, the only 100% correct behavior would probably be to make the filesystem readonly. --b.