dm: consolidate target deregistration error handling

Change dm_unregister_target to return void and use BUG() for error
reporting.

dm_unregister_target can only fail because of programming bug in the
target driver. It can't fail because of user's behavior or disk errors.

This patch changes unregister_target to return void and use BUG if
someone tries to unregister non-registered target or unregister target
that is in use.

This patch removes code duplication (testing of error codes in all dm
targets) and reports bugs in just one place, in dm_unregister_target. In
some target drivers, these return codes were ignored, which could lead
to a situation where bugs could be missed.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 2 insertions, 9 deletions

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 4ceedd4f22af..a8005b43a06b 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1470,17 +1470,10 @@ static int __init dm_snapshot_init(void)
 
 static void __exit dm_snapshot_exit(void)
 {
-        int r;
-
         destroy_workqueue(ksnapd);
 
-        r = dm_unregister_target(&snapshot_target);
-        if (r)
-                DMERR("snapshot unregister failed %d", r);
-
-        r = dm_unregister_target(&origin_target);
-        if (r)
-                DMERR("origin unregister failed %d", r);
+        dm_unregister_target(&snapshot_target);
+        dm_unregister_target(&origin_target);
 
         exit_origin_hash();
         kmem_cache_destroy(pending_cache);