bdev_logical_block_size(dm_snap_cow(ps->store->snap)->
bdev) >> 9);
ps->store->chunk_mask = ps->store->chunk_size - 1;
- ps->store->chunk_shift = ffs(ps->store->chunk_size) - 1;
+ ps->store->chunk_shift = __ffs(ps->store->chunk_size);
chunk_size_supplied = 0;
}