fs: Fix file mode for O_TMPFILE

O_TMPFILE, like O_CREAT, should respect the requested mode and should
create regular files.

This fixes two bugs: O_TMPFILE required privilege (because the mode
ended up as 000) and it produced bogus inodes with no type.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/open.c

@@ -823,7 +823,7 @@ static inline int build_open_flags(int flags, umode_t mode, struct open_flags *o
 	int lookup_flags = 0;
 	int acc_mode;
 
-	if (flags & O_CREAT)
+	if (flags & (O_CREAT | __O_TMPFILE))
 		op->mode = (mode & S_IALLUGO) | S_IFREG;
 	else
 		op->mode = 0;