fuse: handle synchronous iocbs internally

Based on a patch from Maxim Patlasov <MPatlasov@parallels.com>.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 1cdfb07..7354dc1 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -263,6 +263,7 @@
 	int err;
 	struct kiocb *iocb;
 	struct file *file;
+	struct completion *done;
 };
 
 /**