allow O_TMPFILE to work with O_WRONLY

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/open.c b/fs/open.c
index 9156cb0..d53e298 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -844,6 +844,8 @@
 		if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
 			return -EINVAL;
 		acc_mode = MAY_OPEN | ACC_MODE(flags);
+		if (!(acc_mode & MAY_WRITE))
+			return -EINVAL;
 	} else if (flags & O_PATH) {
 		/*
 		 * If we have O_PATH in the open flag. Then we