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=-2.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 900F5C5518A for ; Fri, 24 Apr 2020 07:05:20 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 63D3B20700 for ; Fri, 24 Apr 2020 07:05:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="o8Tw/7tS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 63D3B20700 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=zC+RMf7iS4Pj54vFiQYQIN+949h5rXkrcYgKLjmD9DY=; b=o8Tw/7tSnVzxEf GMfagdNbU52Lom/6pP5p+iBRMxaoz8C7cYhsUxR8fP0iw7Gb7DdIL3hrpLAj1rAc/hwTsAgcJrvaJ 6p3HwyAZknYX/S4AA0fWZAgzMY265rOxjcxZOr9L6caNFqx2DA6MKfrIXRi9NXHdSn4/maX/ndoo4 U+Py930sGc4Bcw8cP/5WjMrsN7RXrBQd0v+gAe2weIQIg0vhQBAjpuepyHLgZ8MghNCroCaPpoG2T D2iWHUgoD2TOjA86q07Yob2MNXJxdWDe2RGXC8Q+HlEaJWOxeIibdNt4ovLj+ufu0t/AqOuwqXhNO dymJhIWCoHRfTkmDMsUw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jRsOh-0001AI-BO; Fri, 24 Apr 2020 07:05:15 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jRsOZ-0007h6-Nt for linux-nvme@lists.infradead.org; Fri, 24 Apr 2020 07:05:14 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id DF81E68CEE; Fri, 24 Apr 2020 09:05:02 +0200 (CEST) Date: Fri, 24 Apr 2020 09:05:02 +0200 From: Christoph Hellwig To: Sagi Grimberg Subject: Re: [PATCH V3 0/7] nvmet: add target ns revalidate support Message-ID: <20200424070502.GA24059@lst.de> References: <20200419234856.59901-1-chaitanya.kulkarni@wdc.com> <20200422081936.GA25035@lst.de> <3f112b29-91cc-620c-6262-de3e322a29fc@grimberg.me> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <3f112b29-91cc-620c-6262-de3e322a29fc@grimberg.me> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200424_000507_944772_3A3F459D X-CRM114-Status: GOOD ( 11.72 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "linux-nvme@lists.infradead.org" , Christoph Hellwig , Chaitanya Kulkarni Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Thu, Apr 23, 2020 at 01:20:25AM -0700, Sagi Grimberg wrote: > This is cumbersome in my mind... and the polling part is > kinda bothering me... > > I still think that having this sit in userspace is so much more > elegant really. > > A simple service that watches with inotify on the device_paths (files or > bdevs - which are also files) and trigger revalidate via configfs when > it gets an attrib event. Eactly - plus udev watch for the block device KOBJ_CHANGE notifications. > > We can even have it watch configfs and automatically add watchers > when new namespaces are enabled and remove watchers when namespaces are > disabled, so it can be completely zero touch. > > This can sit as a simple systemd service that nvmetcli installs. > > I'd very much prefer this over the proposed approach... Same here. The idea of having a kernel thread poll things for which we have notification, and an easy userspace way to handle them just seems like a whole lot of bloat. Also remember the use case: shrinking a volume is a pretty destructive operation and not really practically relevant for a live volume. So the interesting case is growing, and having a little delay or even a manual interaction isn't really the end of the world there. _______________________________________________ linux-nvme mailing list linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme