On Wed, 29 Jul 2015 17:38:44 -0700 Shaohua Li [off-list ref] wrote:

+		while (!list_empty(&log->stripe_end_ios)) {
+			io = list_first_entry(&log->stripe_end_ios,
+				struct r5l_io_unit, log_sibling);
+			list_move_tail(&io->log_sibling, &list);
+			free += (io->log_end - io->log_start +
+				log->total_blocks) % log->total_blocks;
+		}

sorry, forgot to mention this bit.

That '%' is acting on 64 but numbers, so it won't build in a 32bit
machine.
Maybe use SECTOR_DIV, maybe do an 
   if (x > y) free = x-y else free = x+total-y;

or something.

NeilBrown