dm: disable WRITE SAME

WRITE SAME bios are not yet handled correctly by device-mapper so
disable their use on device-mapper devices by setting
max_write_same_sectors to zero.

As an example, a ciphertext device is incompatible because the data
gets changed according to the location at which it written and so the
dm crypt target cannot support it.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
Cc: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 100368eb7991a50c57e473ea20bf4a8441e91ff0..fa295579003175c7c527f0d609afc921bb6c1e96 100644 (file)
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1445,6 +1445,8 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
        else
                queue_flag_clear_unlocked(QUEUE_FLAG_NONROT, q);
 
+       q->limits.max_write_same_sectors = 0;
+
        dm_table_set_integrity(t);
 
        /*