** Description changed:
+ [Impact]
+
"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:
+
+ [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;
+ 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,
- 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;
+ }
- 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),
+ 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.
+ Since the DM_UDEV_DISABLE_DM_RULES_FLAG is set, the rule will not match.
+ As a result the link is removed.
** Tags added: sts
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https://bugs.launchpad.net/bugs/1621340
Title:
'multipath -r' causes /dev/mapper/<wwid> being removed
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