All of lore.kernel.org
 help / color / mirror / Atom feed
From: Martin Wilck <mwilck@suse.com>
To: Hannes Reinecke <hare@suse.de>
Cc: dm-devel@redhat.com
Subject: Re: [PATCH v2 17/20] multipath.rules: find_multipaths "smart" logic
Date: Thu, 29 Mar 2018 11:15:08 +0200	[thread overview]
Message-ID: <1522314908.3669.4.camel@suse.com> (raw)
In-Reply-To: <20180329080437.51205fda@pentland.suse.de>

On Thu, 2018-03-29 at 08:04 +0200, Hannes Reinecke wrote:
> 
> > The only way I see to avoid this is to try calling open(O_EXCL) on
> > the
> > path device in "multipath -u". So far we've avoided that because
> > it's
> > not completely race-free. But we're not talking about a race here,
> > but
> > a situation where some entity grabbed a device before pivot-root.
> > So we could attempt open(O_EXCL) only in the "is maybe a valid
> > path"
> > case, and only return "maybe" if that open succeeds. Otherwise we'd
> > return "no", as we already checked that the device isn't currently
> > part of a multipath map.
> > 
> 
> Ho-hum.
> 
> Watch out when you do this; systemd will generate another event
> whenever you close this fd, and suddenly you find yourself in a
> middle
> of an event storm ...

Thanks for mentioning that.

Udev listens for inotify events for "close after write". We will do the
test with O_RDONLY|O_EXCL, so no event should be generated. Moreover,
events should only occur if udev is watching the device, which
shouldn't be the case while an event is processed (but I'm not 100%
certain about that). Anyway, I'll test this.
 
Cheers,
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
dm-devel@redhat.com
https://www.redhat.com/mailman/listinfo/dm-devel

  reply	other threads:[~2018-03-29  9:15 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-19 15:01 [PATCH v2 00/20] multipath path classification Martin Wilck
2018-03-19 15:01 ` [PATCH v2 01/20] Revert "multipath: ignore -i if find_multipaths is set" Martin Wilck
2018-03-23 17:51   ` Benjamin Marzinski
2018-03-19 15:01 ` [PATCH v2 02/20] Revert "multipathd: imply -n " Martin Wilck
2018-03-23 17:51   ` Benjamin Marzinski
2018-03-19 15:01 ` [PATCH v2 03/20] libmultipath: should_multipath: keep existing maps Martin Wilck
2018-03-23 17:51   ` Benjamin Marzinski
2018-03-19 15:01 ` [PATCH v2 04/20] multipath -u -i: respect entries in WWIDs file Martin Wilck
2018-03-23 17:54   ` Benjamin Marzinski
2018-03-19 15:01 ` [PATCH v2 05/20] libmultipath: trigger change uevent on new device creation Martin Wilck
2018-03-19 15:01 ` [PATCH v2 06/20] libmultipath: trigger path uevent only when necessary Martin Wilck
2018-03-23 17:58   ` Benjamin Marzinski
2018-03-19 15:01 ` [PATCH v2 07/20] libmultipath: change find_multipaths option to multi-value Martin Wilck
2018-03-23 20:07   ` Benjamin Marzinski
2018-03-19 15:01 ` [PATCH v2 08/20] libmultipath: use const char* in open_file() Martin Wilck
2018-03-23 20:08   ` Benjamin Marzinski
2018-03-19 15:01 ` [PATCH v2 09/20] libmultipath: functions to indicate mapping failure in /dev/shm Martin Wilck
2018-03-19 15:01 ` [PATCH v2 10/20] libmultipath: indicate wwid failure in dm_addmap_create() Martin Wilck
2018-03-26 17:52   ` Benjamin Marzinski
2018-03-26 20:07     ` Martin Wilck
2018-03-19 15:01 ` [PATCH v2 11/20] libmultipath: don't try to set up failed wwids again Martin Wilck
2018-03-26 18:47   ` Benjamin Marzinski
2018-03-26 20:13     ` Martin Wilck
2018-03-19 15:01 ` [PATCH v2 12/20] multipath -u: common code path for result message Martin Wilck
2018-03-26 18:59   ` Benjamin Marzinski
2018-03-19 15:01 ` [PATCH v2 13/20] multipath -u: change output to environment/key format Martin Wilck
2018-03-26 19:33   ` Benjamin Marzinski
2018-03-26 20:35   ` Benjamin Marzinski
2018-03-19 15:01 ` [PATCH v2 14/20] multipath -u: add DM_MULTIPATH_DEVICE_PATH=2 for "maybe" Martin Wilck
2018-03-26 20:41   ` Benjamin Marzinski
2018-03-19 15:01 ` [PATCH v2 15/20] libmultipath: implement find_multipaths_timeout Martin Wilck
2018-03-26 22:16   ` Benjamin Marzinski
2018-03-19 15:01 ` [PATCH v2 16/20] libmultipath: enable find_multipaths "smart" Martin Wilck
2018-03-26 22:23   ` Benjamin Marzinski
2018-03-19 15:01 ` [PATCH v2 17/20] multipath.rules: find_multipaths "smart" logic Martin Wilck
2018-03-27 21:03   ` Benjamin Marzinski
2018-03-27 21:34     ` Martin Wilck
2018-03-27 23:07       ` Benjamin Marzinski
2018-03-28 14:51         ` Martin Wilck
2018-03-28 17:12           ` Benjamin Marzinski
2018-03-29  6:04           ` Hannes Reinecke
2018-03-29  9:15             ` Martin Wilck [this message]
2018-03-19 15:01 ` [PATCH v2 18/20] multipathd: decrease log level of "spurious uevent" message Martin Wilck
2018-03-19 15:01 ` [PATCH v2 19/20] libmultipath: decrease log level of uevent filter/merge messages Martin Wilck
2018-03-19 15:01 ` [PATCH v2 20/20] multipathd: decrease log level of waiter thread start/stop msgs Martin Wilck

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1522314908.3669.4.camel@suse.com \
    --to=mwilck@suse.com \
    --cc=dm-devel@redhat.com \
    --cc=hare@suse.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.