trans: improve the performance of dir_lookup in fakeroot

Previously any FS_RETRY_NORMAL requests were handed back to the
client.  Redo the lookup ourself instead.  This saves us the burden to
create a fake node for the intermediate step, hand it back to the
client and handle another request from the client.

With this change there is no need to fiddle with the permission bits
as it was previously done.

* trans/fakeroot.c (netfs_S_dir_lookup): Redo the lookup transparently
  for the user if FS_RETRY_NORMAL is requested.

fixup_improve_perf

1 files changed, 8 insertions, 4 deletions

diff --git a/trans/fakeroot.c b/trans/fakeroot.c
index 1ab32167..6e3b5d4b 100644
--- a/trans/fakeroot.c
+++ b/trans/fakeroot.c
@@ -267,6 +267,14 @@ netfs_S_dir_lookup (struct protid *diruser,
       goto redo_lookup;
 
     case FS_RETRY_NORMAL:
+      if (retry_name[0] != '\0')
+	{
+	  dir = file;
+	  filename = retry_name;
+	  goto redo_lookup;
+	}
+      break;
+
     case FS_RETRY_MAGICAL:
     default:
       if (file == MACH_PORT_NULL)
@@ -305,10 +313,6 @@ netfs_S_dir_lookup (struct protid *diruser,
 	      /* We already know about this node.  */
 	      mach_port_deallocate (mach_task_self (), idport);
 	      pthread_mutex_lock (&np->lock);
-	      if (retry_name[0] != '\0')
-		/* This was not the last component, remove O_WRITE to
-		   avoid opening directories with it.  */
-		flags &= ~O_WRITE;
 	      err = check_openmodes (np->nn, (flags & (O_RDWR|O_EXEC)), file);
 	      if (!err)
 		netfs_nref (np);