in io_eagain, make sure the kernel knows we wanted to write to the

descriptor in case we optimized the syscall away previously
in iob_send leave loop if we got a partial write

io/io_eagain.c

@@ -5,6 +5,8 @@ void io_eagain(int64 d) {
   if (e) {
     if (e->wantread) e->canread=0;
     if (e->wantwrite) e->canwrite=0;
+    if (e->wantwrite && !e->kernelwantwrite)
+      io_wantwrite(d);
 #if defined(HAVE_SIGIO)
     if (d==alt_curread) {
 #if 0

io/io_eagain_write.c

@@ -4,6 +4,8 @@ void io_eagain_write(int64 d) {
   io_entry* e=iarray_get(&io_fds,d);
   if (e) {
     e->canwrite=0;
+    if (e->wantwrite && !e->kernelwantwrite)
+      io_wantwrite(d);
 #if defined(HAVE_SIGIO)
     if (d==alt_curwrite) {
 #if 0

io/iob_send.c

@@ -286,13 +286,13 @@ eagain:
 		  io_eagain_write(s);
 		  return -1;
 		}
-		sent = totalsent;
 		// fall through
 	      }
 	      // actual error
 	      break;
 	    }
-	    // if we get here, we wrote it all
+	    // if we get here, we wrote it all or we got an EAGAIN after
+	    // writing something. Treat as regular partial write.
 	    sent = totalsent;
 	  } else
 	    sent=sendmsg(s,&msg,MSG_MORE|ZEROCOPY);
@@ -354,6 +354,7 @@ eagain:
 	}
       }
       io_eagain_write(s);
+      return total;
     } else break;
   }
 abort: