From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2B68A3AE6F8 for ; Mon, 23 Mar 2026 16:25:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774283119; cv=none; b=AI/JmnZh2MTjw4Bzz0SPabwP4th/C9c70jPMJxmux5fSMYPkG5dyDrT+8kEpgdKZ0BUTmjgw8aRmxvksLmoHZGl/igKQfMI6iOcnCzZlWq9PdgoOJ3b/cHU7tCtjt3yxLwOz97d4FOZ5dAszqVBtwQnBT9mZXHpJMoYwzqu0tj8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774283119; c=relaxed/simple; bh=EFkJD68Oq1eA6tfWtGSMgmF0+D3IsA8GPjwCCKO0lgM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=r6LLHW8ObBF/pQPhWL4CLshL09Z61np3KrovJIry/LZK+0WK+V+5+yFsUEPcnfxiwx215wsNcNiiqQDxxQfsv5rDNiSvPgIm20XyxiPu+gEOajgHG9suFrU+lAhzfopWlnztZWZLOTJC2rNL0T1XwRVccVpwreXl56l/MT3gvq0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=HyUU6Lar; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="HyUU6Lar" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1774283117; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=slAIW0dtKch4EgP848DAzcYNIaKirnAw7wYX/s5hQN8=; b=HyUU6LarM7CU5sxF4Ntqi3mIy19GgZJ374zxpQW9cdgv9VESDhdOu4/p//v6c5jDxs7xMv J5krmN8eYcKqGYK1L+FDtF1ZMIi7RmvQ3F7bNpO6sx+WwuU9vFPsFIeuIcnk133IwNriaw sAAdOXMB6Ee3Ka4GxzGKQiJuNA0L/o0= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-396-YZNZETtRPaWjTGl26cMyWg-1; Mon, 23 Mar 2026 12:25:10 -0400 X-MC-Unique: YZNZETtRPaWjTGl26cMyWg-1 X-Mimecast-MFC-AGG-ID: YZNZETtRPaWjTGl26cMyWg_1774283109 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D41E3195607B; Mon, 23 Mar 2026 16:25:08 +0000 (UTC) Received: from bmarzins-01.fast.eng.rdu2.dc.redhat.com (bmarzins-01.fast.eng.rdu2.dc.redhat.com [10.6.23.12]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 602FA1955D71; Mon, 23 Mar 2026 16:25:08 +0000 (UTC) Received: from bmarzins-01.fast.eng.rdu2.dc.redhat.com (localhost [127.0.0.1]) by bmarzins-01.fast.eng.rdu2.dc.redhat.com (8.18.1/8.17.1) with ESMTPS id 62NGP7711025265 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Mon, 23 Mar 2026 12:25:07 -0400 Received: (from bmarzins@localhost) by bmarzins-01.fast.eng.rdu2.dc.redhat.com (8.18.1/8.18.1/Submit) id 62NGP6Ph1025264; Mon, 23 Mar 2026 12:25:06 -0400 Date: Mon, 23 Mar 2026 12:25:06 -0400 From: Benjamin Marzinski To: John Garry Cc: martin.petersen@oracle.com, james.bottomley@hansenpartnership.com, hare@suse.com, jmeneghi@redhat.com, linux-scsi@vger.kernel.org, michael.christie@oracle.com, snitzer@kernel.org, dm-devel@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH 00/13] scsi: Core ALUA driver Message-ID: References: <20260317120703.3702387-1-john.g.garry@oracle.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 On Mon, Mar 23, 2026 at 09:57:15AM +0000, John Garry wrote: > On 22/03/2026 17:37, Benjamin Marzinski wrote: > > > I think that this work is a real regression possibility for > > > dm-multipath, so we need to be careful. > > At the risk of showing just how limited my SCSI knowledge is, I need to > > ask, Is any of this actually necessary to get native scsi multipath > > working with Implicit ALUA? > > > > If the goal is to limit this to IMPLICT ALUA only, I was expecting that > > you could just leave the scsi_dh_alua code completely alone. If native > > scsi multipathing didn't disable the device handler, it seemed that this > > would basically just work. With the device handler attached, > > We only get the scsi_dh_activate() -> alua_activate() call from dm-mpath.c, > and that callchain could not happen for native SCSI multipath. But, yes, we > do the alua_rtpg_queue() call from a rescan, but we should be checking if > the path is available first (and not rely on a rescan). > > > when the > > array updates the ALUA state, that should, at least I believe, trigger a > > unit attention that will fire off a RTPG command. That should update the > > sdev->access_state, which the multipath code could use to pick the > > correct path. Right? What am I missing here? > > Is this just a parallel > > exercise to overhaul the ALUA code? > > The SCSI community would rather not see more usage for device handlers. I guess it depends on what you mean by using a device handler. I don't think the Native SCSI multipath code would need to actively interface with the device handler code to support IMPLICIT ALUA. IIUC, looking at sdev->access_state should be enough to pick the correct path. If that's right, then it doesn't really matter to the multipath code whether this is getting updated in scsi_dh_alua.c or scsi_alua.c. So refactoring the scsi ALUA handling code seems orthogonal to the adding IMPLICIT ALUA support to the Native scsi multipathing code. -Ben > > How we then get ALUA support for native SCSI multipath is the question. My > original series just really duplicated the scsi_dh_alua.c RTPG support for > native SCSI multipath into a limited "core" driver. Hannes thinks that a > core ALUA driver to also support DH would be better (IIUC), which I am > attempting in this series. I will re-iterate that I would rather not touch > scsi_dh_alua.c, unless the changes are simple and obvious(ly correct). > > Thanks, > John