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From: Martin Wilck <mwilck@suse.com>
To: Benjamin Marzinski <bmarzins@redhat.com>
Cc: dm-devel@redhat.com, Julian Andres Klode <julian.klode@canonical.com>
Subject: Re: [PATCH v4 18/20] multipath -u: quick check if path is multipathed
Date: Fri, 13 Apr 2018 19:59:13 +0200	[thread overview]
Message-ID: <1523642353.1518.11.camel@suse.com> (raw)
In-Reply-To: <20180413161243.GF3103@octiron.msp.redhat.com>

On Fri, 2018-04-13 at 11:12 -0500, Benjamin Marzinski wrote:
> On Fri, Apr 13, 2018 at 12:19:12AM +0200, Martin Wilck wrote:
> > On Thu, 2018-04-12 at 13:46 -0500, Benjamin Marzinski wrote:
> > > On Wed, Apr 04, 2018 at 06:16:25PM +0200, Martin Wilck wrote:
> > > > With "find_multipaths smart", we accept paths as valid if they
> > > > are
> > > > already part of a multipath map. This patch avoids doing a full
> > > > path
> > > > and device-mapper map scan for this case, speeding up
> > > > "multipath
> > > > -u"
> > > > considerably.
> > > 
> > > I feel like this supports my idea from 17/20. I really think that
> > > in
> > > smart mode, the only time we should be claiming a device as
> > > multipath
> > > is
> > > on an add event, if it has always been claimed (or pretend
> > > claimed)
> > > as a
> > > multipath path, or if it is currently a multipath path. Once we
> > > have
> > > let
> > > a uevent go by for a path without setting SYSTEMD_READY=0,
> > > anything
> > > else
> > > is free to use it, and we simply can't safely set
> > > SYSTEMD_READY=0,
> > > unless we know that multipathd has already grabbed the device.
> > 
> > We have to remember that in the udev db then. That doesn't work for
> > coldplug aside, but we agree that's not an issue. By checking a
> > suitable udev variable, we can make sure that we never set
> > SYSTEMD_READY=0 after having released the device to the system.
> 
> We can safely set SYSTEMD_READY=0 if we know that the device is now
> part
> of an existing multipath device, but yeah.

Patch set v5 will implement this logic. I'm currently testing it. I
simply look at DM_MULTIPATH_DEVICE_PATH as saved in the udev db.

Regards
Martin

-- 
Dr. Martin Wilck <mwilck@suse.com>, Tel. +49 (0)911 74053 2107
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)

--
dm-devel mailing list
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https://www.redhat.com/mailman/listinfo/dm-devel

  reply	other threads:[~2018-04-13 17:59 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-04 16:16 [PATCH v4 00/20] multipath path classification Martin Wilck
2018-04-04 16:16 ` [PATCH v4 01/20] Revert "multipath: ignore -i if find_multipaths is set" Martin Wilck
2018-04-04 16:16 ` [PATCH v4 02/20] Revert "multipathd: imply -n " Martin Wilck
2018-04-04 16:16 ` [PATCH v4 03/20] libmultipath: should_multipath: keep existing maps Martin Wilck
2018-04-04 16:16 ` [PATCH v4 04/20] multipath -u -i: respect entries in WWIDs file Martin Wilck
2018-04-04 16:16 ` [PATCH v4 05/20] libmultipath: trigger change uevent on new device creation Martin Wilck
2018-04-04 16:16 ` [PATCH v4 06/20] libmultipath: trigger path uevent only when necessary Martin Wilck
2018-04-04 16:16 ` [PATCH v4 07/20] libmultipath: change find_multipaths option to multi-value Martin Wilck
2018-04-12 18:32   ` Benjamin Marzinski
2018-04-13 18:23   ` Martin Wilck
2018-04-04 16:16 ` [PATCH v4 08/20] libmultipath: use const char* in open_file() Martin Wilck
2018-04-04 16:16 ` [PATCH v4 09/20] libmultipath: functions to indicate mapping failure in /dev/shm Martin Wilck
2018-04-12 18:33   ` Benjamin Marzinski
2018-04-12 20:07     ` Martin Wilck
2018-04-12 21:27       ` Benjamin Marzinski
2018-04-04 16:16 ` [PATCH v4 10/20] libmultipath: indicate wwid failure in dm_addmap_create() Martin Wilck
2018-04-12 18:33   ` Benjamin Marzinski
2018-04-12 20:16     ` Martin Wilck
2018-04-12 20:22       ` Martin Wilck
2018-04-12 21:32         ` Benjamin Marzinski
2018-04-12 22:43           ` Martin Wilck
2018-04-04 16:16 ` [PATCH v4 11/20] multipath -u: common code path for result message Martin Wilck
2018-04-12 18:34   ` Benjamin Marzinski
2018-04-04 16:16 ` [PATCH v4 12/20] multipath -u: change output to environment/key format Martin Wilck
2018-04-12 18:35   ` Benjamin Marzinski
2018-04-04 16:16 ` [PATCH v4 13/20] multipath -u: treat failed wwids as invalid Martin Wilck
2018-04-12 18:35   ` Benjamin Marzinski
2018-04-04 16:16 ` [PATCH v4 14/20] multipath -u: add DM_MULTIPATH_DEVICE_PATH=2 for "maybe" Martin Wilck
2018-04-04 16:16 ` [PATCH v4 15/20] libmultipath: implement find_multipaths_timeout Martin Wilck
2018-04-12 18:35   ` Benjamin Marzinski
2018-04-04 16:16 ` [PATCH v4 16/20] multipath -u : set FIND_MULTIPATHS_WAIT_UNTIL from /dev/shm Martin Wilck
2018-04-12 18:36   ` Benjamin Marzinski
2018-04-12 20:35     ` Martin Wilck
2018-04-12 21:35       ` Benjamin Marzinski
2018-04-04 16:16 ` [PATCH v4 18/20] multipath -u: quick check if path is multipathed Martin Wilck
2018-04-12 18:46   ` Benjamin Marzinski
2018-04-12 22:19     ` Martin Wilck
2018-04-13 16:12       ` Benjamin Marzinski
2018-04-13 17:59         ` Martin Wilck [this message]
2018-04-04 16:16 ` [PATCH v4 19/20] libmultipath: enable find_multipaths "smart" Martin Wilck
2018-04-12 18:47   ` Benjamin Marzinski
2018-04-12 22:27     ` Martin Wilck
2018-04-13 15:59       ` Benjamin Marzinski
2018-04-04 16:16 ` [PATCH v4 20/20] multipath.rules: find_multipaths "smart" logic Martin Wilck
2018-04-12 18:48   ` Benjamin Marzinski
2018-04-13 16:01     ` Benjamin Marzinski

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