Lend the worker a pointer to req/bo's vsl to allow us to simplify some

function arguments.

bin/varnishd/cache/cache.h

@@ -349,6 +349,7 @@ struct worker {
 	struct busyobj		*nbo;
 	void			*nhashpriv;
 	struct dstat		stats[1];
+	struct vsl_log		*vsl;		// borrowed from req/bo
 
 	struct pool_task	task;
 
@@ -468,6 +469,7 @@ struct busyobj {
 	unsigned		refcount;
 	int			retries;
 	struct req		*req;
+	struct worker		*wrk;
 
 	uint8_t			*vary;
 

bin/varnishd/cache/cache_fetch.c

@@ -858,6 +858,8 @@ vbf_fetch_thread(struct worker *wrk, void *priv)
 	VSLb_ts_busyobj(bo, "Start", W_TIM_real(wrk));
 
 	bo->stats = wrk->stats;
+	bo->wrk = wrk;
+	wrk->vsl = bo->vsl;
 
 	while (stp != F_STP_DONE) {
 		CHECK_OBJ_NOTNULL(bo, BUSYOBJ_MAGIC);
@@ -899,6 +901,7 @@ vbf_fetch_thread(struct worker *wrk, void *priv)
 
 	bo->stats = NULL;
 
+	wrk->vsl = NULL;
 	VBO_DerefBusyObj(wrk, &bo);
 	THR_SetBusyobj(NULL);
 }

bin/varnishd/cache/cache_pool.c

@@ -363,6 +363,7 @@ Pool_Work_Thread(void *priv, struct worker *wrk)
 		CHECK_OBJ_NOTNULL(wrk, WORKER_MAGIC);
 
 		WS_Reset(wrk->aws, NULL);
+		AZ(wrk->vsl);
 
 		tp = VTAILQ_FIRST(&pp->front_queue);
 		if (tp != NULL) {

bin/varnishd/cache/cache_req_fsm.c

@@ -880,6 +880,7 @@ CNT_Request(struct worker *wrk, struct req *req)
 	AN(req->vsl->wid & VSL_CLIENTMARKER);
 
 	req->wrk = wrk;
+	wrk->vsl = req->vsl;
 
 	for (nxt = REQ_FSM_MORE; nxt == REQ_FSM_MORE; ) {
 		/*
@@ -913,6 +914,7 @@ CNT_Request(struct worker *wrk, struct req *req)
 		WS_Assert(wrk->aws);
 		CHECK_OBJ_ORNULL(wrk->nobjhead, OBJHEAD_MAGIC);
 	}
+	wrk->vsl = NULL;
 	if (nxt == REQ_FSM_DONE) {
 		AN(req->vsl->wid);
 		if (req->res_mode & (RES_ESI|RES_ESI_CHILD))