** Also affects: multipath-tools (Ubuntu Yakkety)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1621340
Title:
[SRU]'multipath -r' causes /dev/mapper/<wwid> being removed
Status in multipath-tools package in Ubuntu:
In Progress
Status in multipath-tools source package in Xenial:
In Progress
Status in multipath-tools source package in Yakkety:
New
Bug description:
[Impact]
"multipath -r" causes the /dev/mapper/<wwid> to disappear momentarily,
which leads to some issue in consumer applications as such OpenStack.
[Test Case]
* connect to an multipath iscsi target
* multipath -r
* /dev/mapper/<wwid> disappears momentarily
[Regression Potential]
* None
"multipath -r" causes the /dev/mapper/<wwid> to disappear momentarily, which
leads to some issue in consumer applications as such OpenStack. After some
investigation, I found that /dev/mapper/<wwid> was deleted by udev during the
reload, and it was re-created soon later by multipathd (livdevmapper code of
cause). Detailed findings are as follows:
For reload in domap (rename as well),
case ACT_RELOAD:
r = dm_addmap_reload(mpp, params);
if (r)
r = dm_simplecmd_noflush(DM_DEVICE_RESUME, mpp->alias,
0, MPATH_UDEV_RELOAD_FLAG);
break;
it passes 0 to dm_simplecmd_noflush as argument for needsync, which
makes dm_task_set_cookie call being skipped in dm_simplecmd,
if (udev_wait_flag && !dm_task_set_cookie(dmt, &cookie,
((conf->daemon)? DM_UDEV_DISABLE_LIBRARY_FALLBACK : 0) | udev_flags)) {
dm_udev_complete(cookie);
goto out;
}
because of the short-circuit evaluation. Thus _do_dm_ioctl in
libdevmapper will add DM_UDEV_DISABLE_DM_RULES_FLAG flag to
dmi->event_nr, and that will eventually be used in the udev rules
(55-dm.rules),
ENV{DM_UDEV_DISABLE_DM_RULES_FLAG}!="1", ENV{DM_NAME}=="?*",
SYMLINK+="mapper/$env{DM_NAME}"
Since the DM_UDEV_DISABLE_DM_RULES_FLAG is set, the rule will not
match. As a result the link is removed.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/multipath-tools/+bug/1621340/+subscriptions
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