drbd: Work on permission enforcement

Now we have the capabilities of the sending process available,
use them to enforce CAP_SYS_ADMIN.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/include/linux/drbd.h b/include/linux/drbd.h
index 69dc711..233db5c 100644
--- a/include/linux/drbd.h
+++ b/include/linux/drbd.h
@@ -138,6 +138,7 @@
 	ERR_VERIFY_RUNNING	= 149, /* DRBD 8.2 only */
 	ERR_DATA_NOT_CURRENT	= 150,
 	ERR_CONNECTED		= 151, /* DRBD 8.3 only */
+	ERR_PERM		= 152,
 
 	/* insert new ones above this line */
 	AFTER_LAST_ERR_CODE