[PATCH v3 3/6] 11-dm-mpath.rules: handle reloads during coldplug events

[Martin Wilck <martin.wilck@suse.com>]

If a map reload happens while udev is processing rules for a coldplug
event, DM_SUSPENDED may be set if the respective test in 10-dm.rules
happens while the device is suspened. This will cause the rules for all
higher block device layers to be skipped. Record this situation in an udev
property. The reload operation will trigger another "change" uevent later,
which would normally be treated as a reload, and be ignored without
rescanning the device. If a previous "coldplug while suspended" situation is
detected, perform a full device rescan instead.

Signed-off-by: Martin Wilck <mwilck@suse.com>
---
 multipath/11-dm-mpath.rules.in | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/multipath/11-dm-mpath.rules.in b/multipath/11-dm-mpath.rules.in
index fd8d202..30d6e78 100644
--- a/multipath/11-dm-mpath.rules.in
+++ b/multipath/11-dm-mpath.rules.in
@@ -5,9 +5,16 @@ ENV{DM_UUID}!="mpath-?*", GOTO="mpath_end"
 IMPORT{db}="DM_DISABLE_OTHER_RULES_FLAG_OLD"
 IMPORT{db}="MPATH_DEVICE_READY"
 
+# Coldplug event while device is suspended (e.g. during a reload)
+ACTION=="add", ENV{DM_ACTIVATION}=="1", ENV{DM_SUSPENDED}=="1", \
+	PROGRAM="/bin/logger -t 11-dm-mpath.rules -p daemon.warning \"Coldplug event for suspended device\"", \
+	ENV{DM_COLDPLUG_SUSPENDED}="1", GOTO="scan_import"
+
 # If this uevent didn't come from dm, don't try to update the
 # device state
-ENV{DM_COOKIE}!="?*", ENV{DM_ACTION}!="PATH_*", IMPORT{db}="DM_NOSCAN", GOTO="scan_import"
+ENV{DM_COOKIE}!="?*", ENV{DM_ACTION}!="PATH_*", \
+	IMPORT{db}="DM_NOSCAN", IMPORT{db}="DM_COLDPLUG_SUSPENDED", \
+	GOTO="scan_import"
 
 ENV{.MPATH_DEVICE_READY_OLD}="$env{MPATH_DEVICE_READY}"
 
@@ -43,6 +50,16 @@ ENV{DM_ACTION}=="PATH_FAILED", GOTO="mpath_action"
 ENV{MPATH_DEVICE_READY}="1"
 
 LABEL="mpath_action"
+
+# A previous coldplug event occurred while the device was suspended.
+# Activation might have been partially skipped. Activate the device now,
+# i.e. disable the MPATH_UNCHANGED logic and set DM_ACTIVATION=1.
+IMPORT{db}="DM_COLDPLUG_SUSPENDED"
+ENV{DM_COLDPLUG_SUSPENDED}=="1", ENV{DM_SUSPENDED}!="1", \
+	ENV{DM_ACTIVATION}="1", ENV{MPATH_UNCHANGED}="0", \
+	PROGRAM="/bin/logger -t 11-dm-mpath.rules -p daemon.notice \"Forcing activation of previously suspended device\"", \
+	GOTO="force_activation"
+
 # DM_SUBSYSTEM_UDEV_FLAG0 is the "RELOAD" flag for multipath subsystem.
 # Drop the DM_ACTIVATION flag here as mpath reloads tables if any of its
 # paths are lost/recovered. For any stack above the mpath device, this is not
@@ -57,6 +74,8 @@ ENV{DM_SUBSYSTEM_UDEV_FLAG0}=="1", \
 ENV{DM_ACTION}=="PATH_FAILED|PATH_REINSTATED", \
 	ENV{DM_ACTIVATION}="0", ENV{MPATH_UNCHANGED}="1"
 
+LABEL="force_activation"
+
 # Do not initiate scanning if no path is available,
 # otherwise there would be a hang or IO error on access.
 # We'd like to avoid this, especially within udev processing.
@@ -99,6 +118,9 @@ IMPORT{db}="ID_PART_GPT_AUTO_ROOT"
 
 LABEL="import_end"
 
+# Reset previous DM_COLDPLUG_SUSPENDED if activation happens now
+ENV{DM_SUSPENDED}!="1", ENV{DM_ACTIVATION}=="1", ENV{DM_COLDPLUG_SUSPENDED}=""
+
 # Multipath maps should take precedence over their members.
 ENV{DM_UDEV_LOW_PRIORITY_FLAG}!="1", OPTIONS+="link_priority=50"
 
-- 
2.43.0