Sanitize qnx4 fsync handling

* have directory operations use mark_buffer_dirty_inode(),
  so that sync_mapping_buffers() would get those.
* make qnx4_write_inode() honour its last argument.
* get rid of insane copies of very ancient "walk the indirect blocks"
  in qnx4/fsync - they never matched the actual fs layout and, fortunately,
  never'd been called.  Again, all this junk is not needed; ->fsync()
  should just do sync_mapping_buffers + sync_inode (and if we implement
  block allocation for qnx4, we'll need to use mark_buffer_dirty_inode()
  for extent blocks)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/qnx4/file.c b/fs/qnx4/file.c
index 867f42b..e7033ea 100644
--- a/fs/qnx4/file.c
+++ b/fs/qnx4/file.c
@@ -29,7 +29,7 @@
 #ifdef CONFIG_QNX4FS_RW
 	.write		= do_sync_write,
 	.aio_write	= generic_file_aio_write,
-	.fsync		= qnx4_sync_file,
+	.fsync		= simple_fsync,
 #endif
 };