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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 286FACC6B16 for ; Tue, 13 Oct 2026 15:36:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=cuEKs4xbOD0Ymx6z6GCF2PockKopMGRNzqpG6R9Bh+Y=; b=W0dGpxtOb05VDCESVcd2EVK0zJ 0JRZT/8/gY7AmxfPn8myP6Ys2QfgdFOZoVwpqpw4Ppb46uwc+NZrPXOHw9lUK4PBkn/gxukAAgZTi a6oxonJsYUJsc29Y3H3ulu4sQ1v5S2aZtZbCdmJDRYBkRjVRPkp45/fmKPLeD+93r7bk6PWJoWYvR pmfWiTPqiUqAeDKW9b4TR7XTymK4c2dggNQ9cQedVVyAJY6DBeu+/YC+kWG1b8TXAUJiVtHYkKyfq drmkZujbD/kG+sakeYkFTKe9SD/REGpxIFtg/60dZhIl956jgM52oO/M0ehNZl5d33VbUnOMa67Ac B2YYGZAw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xGeY4-0000000DMmM-2BiP; Tue, 13 Oct 2026 15:36:16 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xGeY2-0000000DMm0-26re for linux-nvme@lists.infradead.org; Tue, 13 Oct 2026 15:36:15 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id EE9FF60A5A; Tue, 13 Oct 2026 15:36:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 68D221F00893; Tue, 13 Oct 2026 15:36:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791905773; bh=cuEKs4xbOD0Ymx6z6GCF2PockKopMGRNzqpG6R9Bh+Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=J8FmKVBYw972xk4qMRXwm3J/s5ZTsQIULRdvuvViy/QoLWYVTPXY7qzAzULdlxVgV w3BYUS6eIqygzlf1GxWiGOjmKR9zpXv76fQrmHsCgx1YTOa3Vk9ej9j1tQia9Arxyg rdw0AKYsuH25UEZBQL1ohC516t5y+wy894CnCl79cpmh+5tP6MCDeZKPE6LfOrumrE X1J3rm8kXafBEi3WkB4rpGOE+dFL/3alAfh4y8TQc1l8cfhE6FPEJhDhaX9rkD+fLi Y81ADeeKtImboLqrS+EUt0Ps/Wqb8UecWVWkDuwgsPih7+0i+r9c8U/0JaqR8oH6VU KHjTmMA9G08OA== Date: Tue, 13 Oct 2026 09:36:12 -0600 From: Keith Busch To: Martin George Cc: linux-nvme@lists.infradead.org, hch@lst.de, sagi@grimberg.me, loberman@redhat.com, Martin George Subject: Re: [PATCH] nvme-multipath: report "none" iopolicy for discovery subsystems Message-ID: References: <20260930153658.4002-1-marting@netapp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260930153658.4002-1-marting@netapp.com> X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Wed, Sep 30, 2026 at 09:06:58PM +0530, Martin George wrote: > A discovery subsystem never exposes namespaces, so it has no multipath > head and no I/O paths to select between. Nevertheless the per-subsystem > iopolicy attribute is registered unconditionally and reads back the > driver-wide default which is 'numa' for the discovery subsystems too. > This can be misleading as it suggests a path selection policy is in > effect when nothing is ever selected, and writing the attribute silently > mutates state that can never be used. > > Report "none" instead for a discovery subsystem, and reject writes > with -EOPNOTSUPP. Report "none" from iopolicies as well, so that the > value read from iopolicy always remains a member of the set advertised > by iopolicies; otherwise userspace validating the current policy > against the available ones would reject its own subsystem. > > And while at it, document iopolicies too, which was not covered when it > was added previously. Thanks, applied to nvme-7.4.