max_discard_sectors only 32bits, and some non scsi backend
devices will set this to the max 0xffffffff, so we can end up
overflowing during the max_unmap_lba_count calculation.
This fixes a regression caused by my patch:
commit 8a9ebe717a
Author: Mike Christie <mchristi@redhat.com>
Date: Mon Jan 18 14:09:27 2016 -0600
target: Fix WRITE_SAME/DISCARD conversion to linux 512b sectors
which can result in extra discards being sent to due the overflow
causing max_unmap_lba_count to be smaller than what the backing
device can actually support.
Signed-off-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: stable@vger.kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
ea263c7fad