FIX: Mdmon crashes after changing RAID level from 1 to 0

Description of the bug:
Sometimes mdmon crashes after changing RAID level from 1 to 0 (takeover).

Cause of the bug:
The managemon marks an active_array for removal from monitoring
by assigning a->container to NULL value (in the "manage_member" function).
Sometimes (during stress test) it happens right when the monitor
is in the "read_and_act" function and a->container pointer is in use.
This causes the monitor crashes.

Solution:
The active array has to be marked for removal in another way
than setting NULL pointer when it can be in use.
A new field "to_remove" was added to the "active_array" structure.
It is used in the managemon to mark a container to remove
(instead of the old assigment: a->container = NULL)
and monitor checks it to determine if the array should be removed.
The field "to_remove" should be checked in some other places
to avoid managing of the array which is going to be removed.

Signed-off-by: Lukasz Dorau <lukasz.dorau@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 1 insertions, 0 deletions

diff --git a/mdmon.h b/mdmon.h
index 6d1776f9..59e1b537 100644
--- a/mdmon.h
+++ b/mdmon.h
@@ -28,6 +28,7 @@ struct active_array {
 	struct mdinfo info;
 	struct supertype *container;
 	struct active_array *next, *replaces;
+	int to_remove;
 
 	int action_fd;
 	int resync_start_fd;