[ 091/221] dm: disable WRITE SAME

Greg Kroah-Hartman
2013-01-15T22:30:23Z

From: Mike Snitzer <snitzer@redhat.com>

commit c1a94672a830e01d58c7c7e8de530c3f136d6ff2 upstream.

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: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/md/dm-table.c | 2 ++
1 file changed, 2 insertions(+)

--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1445,6 +1445,8 @@ void dm_table_set_restrictions(struct dm
else
queue_flag_clear_unlocked(QUEUE_FLAG_NONROT, q);

+ q->limits.max_write_same_sectors = 0;
+
dm_table_set_integrity(t);

/*