[25/99] dm snapshot: require non zero chunk size by end of ctr

[Greg KH]

2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>

commit 3f2412dc85260e5aae7ebb03bf50d5b1407e3083 upstream.

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@xxxxxxxxxx>
Reviewed-by: Jonathan Brassow <jbrassow@xxxxxxxxxx>
Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Alasdair G Kergon <agk@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

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

--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -673,6 +673,11 @@ static int snapshot_ctr(struct dm_target
 	bio_list_init(&s->queued_bios);
 	INIT_WORK(&s->queued_bios_work, flush_queued_bios);
 
+	if (!s->store->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)) {


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