pipe: prevent dumping pipes in the packetized mode

This mode was introduced less than year ago:

commit 9883035ae7edef3ec62ad215611cb8e17d6a1a5d
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun Apr 29 13:12:42 2012 -0700

    pipes: add a "packetized pipe" mode for writing
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

pipes.c

@@ -448,6 +448,11 @@ static int dump_one_pipe(int lfd, u32 id, const struct fd_parms *p)
 	pr_info("Dumping pipe %d with id %#x pipe_id %#x\n",
 			lfd, id, pipe_id(p));
 
+	if (p->flags & O_DIRECT) {
+		pr_err("The packetized mode for pipes is not supported yet\n");
+		return -1;
+	}
+
 	pe.id		= id;
 	pe.pipe_id	= pipe_id(p);
 	pe.flags	= p->flags;