rework the write_blocked() handlers

to match the EOF handlers, so I'm more convinced taht they're
correct.

src/lib/bio/fd.c

@@ -728,12 +728,10 @@ static ssize_t fr_bio_fd_try_connect(fr_bio_fd_t *my)
                  */
         case EINPROGRESS:
 		if (!my->info.write_blocked) {
-			if (my->cb.write_blocked) {
-				rcode = my->cb.write_blocked((fr_bio_t *) my);
-				if (rcode < 0) return rcode;
-			}
-
 			my->info.write_blocked = true;
+
+			rcode = fr_bio_write_blocked((fr_bio_t *) my);
+			if (rcode < 0) return rcode;
 		}
 
 		return fr_bio_error(IO_WOULD_BLOCK);

src/lib/bio/fd_write.h

@@ -24,10 +24,8 @@ if (rcode > 0) {
 		 */
 		my->info.write_blocked = true;
 
-		if (my->cb.write_blocked) {
-			error = fr_bio_write_blocked((fr_bio_t *) my);
-			if (error < 0) return error;
-		}
+		error = fr_bio_write_blocked((fr_bio_t *) my);
+		if (error < 0) return error;
 
 		return rcode;	
 	}

src/lib/bio/mem.c

@@ -369,6 +369,7 @@ static ssize_t fr_bio_mem_read_verify_datagram(fr_bio_t *bio, void *packet_ctx,
  */
 static ssize_t fr_bio_mem_write_next(fr_bio_t *bio, void *packet_ctx, void const *buffer, size_t size)
 {
+	int error;
 	ssize_t rcode;
 	size_t room, leftover;
 	fr_bio_mem_t *my = talloc_get_type_abort(bio, fr_bio_mem_t);
@@ -410,14 +411,13 @@ static ssize_t fr_bio_mem_write_next(fr_bio_t *bio, void *packet_ctx, void const
 		return rcode;
 	}
 
-	if (my->cb.write_blocked) {
-		int error;
-
-		error = my->cb.write_blocked(bio);
-		if (error < 0) return error;
+	/*
+	 *	Tell previous BIOs in the chain that they are blocked.
+	 */
+	error = fr_bio_write_blocked(bio);
+	if (error < 0) return error;
 
-		fr_assert(error != 0); /* what to do? */
-	}
+	fr_assert(error != 0); /* what to do? */
 
 	/*
 	 *	We had WOULD BLOCK, or wrote partial bytes.  Save the data to the memory buffer, and ensure

src/lib/bio/retry.c

@@ -764,7 +764,10 @@ static ssize_t fr_bio_retry_write(fr_bio_t *bio, void *packet_ctx, void const *b
 			my->info.write_blocked = true;
 			my->all_used = true;
 
-			rcode = my->cb.write_blocked(bio);
+			/*
+			 *	Previous BIOs are blocked, but we still try to write retries.
+			 */
+			rcode = fr_bio_write_blocked(bio);
 			if (rcode < 0) return rcode;
 
 			return fr_bio_error(IO_WOULD_BLOCK);