staging: lustre: ldlm: evict clients returning errors on ASTs

To test proper behavior of clients returning errors on ASTs
we can induce a failure with setting OBD_FAIL_LDLM_BL_CALLBACK_NET.
Handle the new additonal case of cfs_fail_err being set as well
so that the cfs_fail_err can be sent back in a reply.
Signed-off-by: Alexey Lyashkov <alexey_lyashkov@xyratex.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5581
Xyratex-bug-id: MRP-2041
Reviewed-on: http://review.whamcloud.com/11752Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/ldlm/ldlm_lockd.c

@@ -559,8 +559,11 @@ static int ldlm_callback_handler(struct ptlrpc_request *req)
 
 	switch (lustre_msg_get_opc(req->rq_reqmsg)) {
 	case LDLM_BL_CALLBACK:
-		if (OBD_FAIL_CHECK(OBD_FAIL_LDLM_BL_CALLBACK_NET))
+		if (OBD_FAIL_CHECK(OBD_FAIL_LDLM_BL_CALLBACK_NET)) {
+			if (cfs_fail_err)
+				ldlm_callback_reply(req, -(int)cfs_fail_err);
 			return 0;
+		}
 		break;
 	case LDLM_CP_CALLBACK:
 		if (OBD_FAIL_CHECK(OBD_FAIL_LDLM_CP_CALLBACK_NET))