From patchwork Wed Dec 15 17:44:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Benjamin Marzinski X-Patchwork-Id: 12678879 X-Patchwork-Delegate: christophe.varoqui@free.fr 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 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.lore.kernel.org (Postfix) with ESMTPS id 81028C433F5 for ; Wed, 15 Dec 2021 17:44:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1639590265; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=A9x4T0IYnhyDedT+ipyV1yaUNz5+CRyNDeHUY01G5N0=; b=RGFOv7EtyzYBly0+B1ooZYechLaK6wX5unrQPc1F/4bnlT+VBt0kwRAHFc212V42xBS7oA ZTAIpz+KIwisI8N+Qws5z6TImH2NS+sKaMjKSTY3fBvS+CR09qy7LX/0Ua7zc/eWe4Z5wW Cr9aOQqw02wmSiFpQ57iikTfdmAy72g= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-504-pid3No7nO-CHhXF_zcJfVA-1; Wed, 15 Dec 2021 12:44:24 -0500 X-MC-Unique: pid3No7nO-CHhXF_zcJfVA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8C0F2802C8F; Wed, 15 Dec 2021 17:44:19 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 71FEC7A227; Wed, 15 Dec 2021 17:44:19 +0000 (UTC) Received: from lists01.pubmisc.prod.ext.phx2.redhat.com (lists01.pubmisc.prod.ext.phx2.redhat.com [10.5.19.33]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id 013CF4CA93; Wed, 15 Dec 2021 17:44:18 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) by lists01.pubmisc.prod.ext.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id 1BFHiIM8018391 for ; Wed, 15 Dec 2021 12:44:18 -0500 Received: by smtp.corp.redhat.com (Postfix) id 402747A229; Wed, 15 Dec 2021 17:44:18 +0000 (UTC) Received: from octiron.msp.redhat.com (unknown [10.15.80.209]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2881B7A225; Wed, 15 Dec 2021 17:44:18 +0000 (UTC) Received: from octiron.msp.redhat.com (localhost.localdomain [127.0.0.1]) by octiron.msp.redhat.com (8.14.9/8.14.9) with ESMTP id 1BFHiGjZ011343; Wed, 15 Dec 2021 11:44:16 -0600 Received: (from bmarzins@localhost) by octiron.msp.redhat.com (8.14.9/8.14.9/Submit) id 1BFHiFWE011342; Wed, 15 Dec 2021 11:44:15 -0600 From: Benjamin Marzinski To: Christophe Varoqui Date: Wed, 15 Dec 2021 11:44:10 -0600 Message-Id: <1639590250-11293-4-git-send-email-bmarzins@redhat.com> In-Reply-To: <1639590250-11293-1-git-send-email-bmarzins@redhat.com> References: <1639590250-11293-1-git-send-email-bmarzins@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-loop: dm-devel@redhat.com Cc: device-mapper development , Martin Wilck Subject: [dm-devel] [PATCH v2 3/3] multipathd: avoid unnecessary path read-only reloads X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com A mulitpath device can only be reloaded read/write when all paths are read/write. Also, whenever a read-only scsi device is rescanned, the scsi subsystem will first unconditionally issue a uevent with DISK_RO=0 before checking the read-only status, and if it the device is still read-only, issuing another uevent with DISK_RO=1. These uevents cause pointless reloads when read-only paths are rescanned. To avoid this, first check if the path is being changed to the existing multipath read-only state. If the state is the same, do nothing. If it's different, check to see if all paths are read/write before changing a multipath device from read-only to read/write. If the multipath device read-only state is unknown, assume that it needs to be reloaded. Signed-off-by: Benjamin Marzinski Reviewed-by: Martin Wilck --- multipathd/main.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 47 insertions(+), 1 deletion(-) diff --git a/multipathd/main.c b/multipathd/main.c index 2e99a266..009a99d9 100644 --- a/multipathd/main.c +++ b/multipathd/main.c @@ -1440,6 +1440,52 @@ finish_path_init(struct path *pp, struct vectors * vecs) return -1; } +static int +sysfs_get_ro (struct path *pp) +{ + int ro; + char buff[3]; /* Either "0\n\0" or "1\n\0" */ + + if (!pp->udev) + return -1; + + if (sysfs_attr_get_value(pp->udev, "ro", buff, sizeof(buff)) <= 0) { + condlog(3, "%s: Cannot read ro attribute in sysfs", pp->dev); + return -1; + } + + if (sscanf(buff, "%d\n", &ro) != 1 || ro < 0 || ro > 1) { + condlog(3, "%s: Cannot parse ro attribute", pp->dev); + return -1; + } + + return ro; +} + +static bool +needs_ro_update(struct multipath *mpp, int ro) +{ + struct pathgroup * pgp; + struct path * pp; + unsigned int i, j; + + if (!mpp || ro < 0) + return false; + if (!has_dm_info(mpp)) + return true; + if (mpp->dmi.read_only == ro) + return false; + if (ro == 1) + return true; + vector_foreach_slot (mpp->pg, pgp, i) { + vector_foreach_slot (pgp->paths, pp, j) { + if (sysfs_get_ro(pp) == 1) + return false; + } + } + return true; +} + static int uev_update_path (struct uevent *uev, struct vectors * vecs) { @@ -1512,7 +1558,7 @@ uev_update_path (struct uevent *uev, struct vectors * vecs) } ro = uevent_get_disk_ro(uev); - if (mpp && ro >= 0) { + if (needs_ro_update(mpp, ro)) { condlog(2, "%s: update path write_protect to '%d' (uevent)", uev->kernel, ro); if (mpp->wait_for_udev)