dm raid: avoid mddev->suspended access

Use runtime flag to ensure that an mddev gets suspended/resumed just once.
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-raid.c

@@ -208,6 +208,7 @@ struct raid_dev {
 #define RT_FLAG_RS_BITMAP_LOADED	2
 #define RT_FLAG_UPDATE_SBS		3
 #define RT_FLAG_RESHAPE_RS		4
+#define RT_FLAG_RS_SUSPENDED		5
 
 /* Array elements of 64 bit needed for rebuild/failed disk bits */
 #define DISKS_ARRAY_ELEMS ((MAX_RAID_DEVICES + (sizeof(uint64_t) * 8 - 1)) / sizeof(uint64_t) / 8)
@@ -3169,6 +3170,7 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	}
 
 	mddev_suspend(&rs->md);
+	set_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags);
 
 	/* Try to adjust the raid4/5/6 stripe cache size to the stripe size */
 	if (rs_is_raid456(rs)) {
@@ -3626,7 +3628,7 @@ static void raid_postsuspend(struct dm_target *ti)
 {
 	struct raid_set *rs = ti->private;
 
-	if (!rs->md.suspended)
+	if (!test_and_set_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags))
 		mddev_suspend(&rs->md);
 
 	rs->md.ro = 1;
@@ -3760,7 +3762,7 @@ static int rs_start_reshape(struct raid_set *rs)
 		return r;
 
 	/* Need to be resumed to be able to start reshape, recovery is frozen until raid_resume() though */
-	if (mddev->suspended)
+	if (test_and_clear_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags))
 		mddev_resume(mddev);
 
 	/*
@@ -3787,8 +3789,8 @@ static int rs_start_reshape(struct raid_set *rs)
 	}
 
 	/* Suspend because a resume will happen in raid_resume() */
-	if (!mddev->suspended)
-		mddev_suspend(mddev);
+	set_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags);
+	mddev_suspend(mddev);
 
 	/*
 	 * Now reshape got set up, update superblocks to
@@ -3884,7 +3886,7 @@ static void raid_resume(struct dm_target *ti)
 	if (!(rs->ctr_flags & RESUME_STAY_FROZEN_FLAGS))
 		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
 
-	if (mddev->suspended)
+	if (test_and_clear_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags))
 		mddev_resume(mddev);
 }