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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 D7034C4363C for ; Sun, 4 Oct 2020 09:59:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9A1CF206C3 for ; Sun, 4 Oct 2020 09:59:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725979AbgJDJ71 convert rfc822-to-8bit (ORCPT ); Sun, 4 Oct 2020 05:59:27 -0400 Received: from jabberwock.ucw.cz ([46.255.230.98]:49862 "EHLO jabberwock.ucw.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725825AbgJDJ71 (ORCPT ); Sun, 4 Oct 2020 05:59:27 -0400 Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id 61A041C0B76; Sun, 4 Oct 2020 11:59:24 +0200 (CEST) Date: Sun, 4 Oct 2020 11:59:23 +0200 From: Pavel Machek To: Metztli Information Technology Cc: edward.shishkin@gmail.com, reiserfs-devel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [ANNOUNCE] Reiser5: Selective File Migration - User Interface Message-ID: <20201004095922.GC1104@bug> References: <20200826205216.07BC868EF679@huitzilopochtli.metztli-it.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: <20200826205216.07BC868EF679@huitzilopochtli.metztli-it.com> User-Agent: Mutt/1.5.23 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > In particular, using this functionality, user is able to push out > > "hot" files on any high-performance device (e.g. proxy device) and pin > > them there. What permissions are normally required for file migration? > > COMMENT. After ioctl successful completion the file is not necessarily > > written to the target device! To make sure of it, call fsync(2) after > > successful ioctl completion, or open the file with O_SYNC flag before > > migration. Ok. > > COMMENT. File migration is a volume operation (like adding, removing a device to/from > > a logical volumes), and all volume operations are serialized. So, any attempt to > > migrate a file, while performing other operation on that volume will fail. If some > > file migration procedure fails (with EBUSY, or other errors), or was interrupted by > > user, then it should be repeated in the current mount session. File migration > > procedures interrupted by system crash, hared reset, etc) should be repeated in the > > next mount sessions. Dunno. Returning -EBUSY is kind of "interesting" there. I'd expect kernel to queue the callers, because userland can't really do that easily. Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html