Look for VFP's also on the per-vcl list

bin/varnishd/cache/cache_fetch.c

@@ -606,7 +606,7 @@ vbf_stp_fetch(struct worker *wrk, struct busyobj *bo)
 	}
 
 	if (bo->filter_list == NULL ||
-	    VCL_StackVFP(bo->vfc, bo->filter_list)) {
+	    VCL_StackVFP(bo->vfc, bo->vcl, bo->filter_list)) {
 		(bo)->htc->doclose = SC_OVERLOAD;
 		VDI_Finish((bo)->wrk, bo);
 		return (F_STP_ERROR);

bin/varnishd/cache/cache_varnishd.h

@@ -407,7 +407,7 @@ int VCL_IterDirector(struct cli *, const char *, vcl_be_func *, void *);
 
 /* cache_vcl_vrt.c */
 void VCL_VRT_Init(void);
-int VCL_StackVFP(struct vfp_ctx *, const char *);
+int VCL_StackVFP(struct vfp_ctx *, const struct vcl *, const char *);
 
 /* cache_vrt.c */
 void VRTPRIV_init(struct vrt_privs *privs);

bin/varnishd/cache/cache_vcl_vrt.c

@@ -470,7 +470,7 @@ VRT_RemoveVFP(VRT_CTX, const struct vfp *filter)
 }
 
 int
-VCL_StackVFP(struct vfp_ctx *vc, const char *fl)
+VCL_StackVFP(struct vfp_ctx *vc, const struct vcl *vcl, const char *fl)
 {
 	const char *p, *q;
 	const struct vfp_filter *vp;
@@ -491,6 +491,14 @@ VCL_StackVFP(struct vfp_ctx *vc, const char *fl)
 			if (!memcmp(p, vp->filter->name, vp->nlen))
 				break;
 		}
+		if (vp == NULL) {
+			VTAILQ_FOREACH(vp, &vcl->vfps, list) {
+				if (vp->nlen != q - p)
+					continue;
+				if (!memcmp(p, vp->filter->name, vp->nlen))
+					break;
+			}
+		}
 		if (vp == NULL)
 			return (VFP_Error(vc,
 			    "Filter '%.*s' not found", (int)(q-p), p));

bin/varnishtest/tests/m00048.vtc

+varnishtest "VMOD vfp"
+
+server s1 {
+	rxreq
+	txresp -body "Ponto Facto, Caesar Transit!"
+} -start
+
+varnish v1 -vcl+backend {
+	import debug;
+
+	sub vcl_backend_response {
+		set beresp.filters = "rot13";
+	}
+} -start
+
+client c1 {
+	txreq
+	rxresp
+	expect resp.body == "Cbagb Snpgb, Pnrfne Genafvg!"
+} -run
+