If we are creating snapshot with memory-stored exception store, fail if
the user didn't specify chunk size. Zero chunk size would probably crash
a lot of places in the rest of snapshot code.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

---
 drivers/md/dm-snap.c |    5 +++++
 1 file changed, 5 insertions(+)

Index: linux-2.6.27-rc3-devel/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.27-rc3-devel.orig/drivers/md/dm-snap.c	2008-08-15 15:40:24.000000000 +0200
+++ linux-2.6.27-rc3-devel/drivers/md/dm-snap.c	2008-08-15 15:41:50.000000000 +0200
@@ -655,6 +655,11 @@ static int snapshot_ctr(struct dm_target
 		DMWARN("Snapshot is marked invalid.");
 	}
 
+	if (!s->chunk_size) {
+		ti->error = "Chunk size not set";
+		goto bad_load_and_register;
+	}
+
 	/* Add snapshot to the list of snapshots for this origin */
 	/* Exceptions aren't triggered till snapshot_resume() is called */
 	if (register_snapshot(s)) {