From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Benjamin Marzinski" Subject: Re: [PATCH RESEND 0/4] multipath-tools: fixes for path wwid detection and path change uevents Date: Fri, 5 Oct 2018 18:07:04 -0500 Message-ID: <20181005230704.GH3172@octiron.msp.redhat.com> References: <20180307232152.15538-1-mwilck@suse.com> <20180314174013.GF14513@octiron.msp.redhat.com> <7aa1314c9095e3315e02525ec2e005030898a9b4.camel@suse.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline In-Reply-To: <7aa1314c9095e3315e02525ec2e005030898a9b4.camel@suse.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Martin Wilck Cc: dm-devel@redhat.com List-Id: dm-devel.ids On Tue, Oct 02, 2018 at 11:02:50PM +0200, Martin Wilck wrote: > Hi Ben, Christophe, > = > I found a problem with this old patch series of mine. > = > while I am still pondering about your latest series, it occured to me > that my patch "get_uid: don't quit prematurely without udev" is against > the spirit of your "retrigger uevents to try and get the uid through > udev" patch from 2016 (688aa22b). > = > "get_uid: don't quit prematurely without udev" has been merged a while > ago (08d42ee6). Should it be reverted?? > = > Pro: the patch is against the "udev first" philosophy and subverts the > retrigger logic. > Con: with the patch, we'll be able to retrieve WWIDs more quickly in > some situations, as we don't have to wait for udev. > = > Either way (but more likely with my patch), it may happen that we > retrieve a WWID from sysfs or elsewhere first, and from udev later. > These WWIDs may not necessarily match, and a "WWID changed" problem may > occur. > = > Please tell me what you think. I'm having a hard time seeing how get_uid() could get called on a path without a udev device attached in multipathd. It can happen because of update_paths() in multipath, for paths that don't get discovered when searching for paths, but do belong to an existing multipath device. I don't think you patch will hurt anything here. So, unless I'm missing some code path in multipathd, I don't see a problem with this patch. In fact, we should probably make scsi_uid_fallback() skip (or at least always pass) the retrigger check if we aren't in the daemon, so we always try the failback when we run multipath. -Ben > = > Martin > = > = > -- = > Dr. Martin Wilck , Tel. +49 (0)911 74053 2107 > SUSE Linux GmbH, GF: Felix Imend=F6rffer, Jane Smithard, Graham Norton > HRB 21284 (AG N=FCrnberg) > =