multipath device action incorrectly being parsed as the device name

[Lee Yarwood]

multipath device action incorrectly being parsed as the device name.

The first word on the first line of `multipath -l $path` is currently being used as the name of a given multipath device.

https://github.com/openstack/nova/blob/master/nova/storage/linuxscsi.py#L118
https://github.com/openstack/os-brick/blob/master/os_brick/initiator/linuxscsi.py#L145

This however can be an `action:` string when the device is being created, reloaded, resized etc. [1][2][3]

[1] https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/DM_Multipath/MPIO_output.html
[2] http://git.opensvc.com/gitweb.cgi?p=multipath-tools/.git;a=blob;f=libmultipath/print.c;h=5d63ed34d2a8816a5e287bdeb1bd90cdb026bb9e;hb=HEAD#l929
[3] http://git.opensvc.com/gitweb.cgi?p=multipath-tools/.git;a=blob;f=libmultipath/configure.h;h=c014b5533226d9a56571f87b9123de91c5ff1d2f;hb=HEAD

[Amador Pahim (apahim)]

I think we should catch the name from /sys/devices/virtual/block/<device>/dm/name. Seems better than parse a txt output.

[Lee Yarwood (lyarwood)]

@apahim we are actually trying to traverse the other way, starting with a single path device and working out the virtual mpath dm device details. We could actually use a glob to do this instead of `multipath -l /dev/path` :

~~~
# ll /sys/devices/virtual/block/*/slaves/sdk
lrwxrwxrwx. 1 root root 0 Jun 3 03:56 /sys/devices/virtual/block/dm-2/slaves/sdk -> ../../../../pci0000:00/0000:00:07.0/0000:1a:00.0/host0/rport-0:0-8/target0:0:3/0:0:3:3/block/sdk
~~~

IMHO moving to this method is out of scope for this bug but I will try to write up a spec detailing how we could use this method in os-brick.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Lee Yarwood (<email address hidden>) on branch: master
Review: https://review.openstack.org/193119

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/245882

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/245882
Committed: https://git.openstack.org/cgit/openstack/os-brick/commit/?id=7900cf38c2da5142c62e59ea7a6160f59f396dae
Submitter: Jenkins
Branch: master

commit 7900cf38c2da5142c62e59ea7a6160f59f396dae
Author: Kendall Nelson <email address hidden>
Date: Thu Nov 5 15:47:53 2015 +0000

    Multipath Device Action Being Parsed as Name

    Whenever find_multipath_device() was being called on an action
    it would include the action as part of the device name. This patch
    creates a list of actions and checks that they aren't preceding
    the device name before parsing the rest of the device information
    in find_multipath_device().

    This patch is based on the approach that was taken in Nova until
    it was abandoned in favor of the change being made in os-brick
    instead. The Change-Id for the Nova change:
    I8f1f769bb15ec10054e2fd73c4cf621389014cf1

    Change-Id: I12a10ba189e4987cdf07bebdadbac0d4587c01d1
    Closes-Bug: 1466444

[Doug Hellmann (doug-hellmann)]

This issue was fixed in the openstack/os-brick 0.6.0 release.