md: Don't let implementation detail of curr_resync leak out through sysfs.

mddev->curr_resync has artificial values of '1' and '2' which are used
by the code which ensures only one resync is happening at a time on
any given device.

These values are internal and should never be exposed to user-space
(except when translated appropriately as in the 'pending' status in
/proc/mdstat).

Unfortunately they are as ->curr_resync is assigned to
->curr_resync_completed and that value is directly visible through
sysfs.

So change the assignments to ->curr_resync_completed to get the same
valued from elsewhere in a form that doesn't have the magic '1' or '2'
values.

Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/md.c

@@ -6824,7 +6824,7 @@ void md_do_sync(mddev_t *mddev)
 		       desc, mdname(mddev));
 		mddev->curr_resync = j;
 	}
-	mddev->curr_resync_completed = mddev->curr_resync;
+	mddev->curr_resync_completed = j;
 
 	while (j < max_sectors) {
 		sector_t sectors;
@@ -6842,8 +6842,7 @@ void md_do_sync(mddev_t *mddev)
 			md_unplug(mddev);
 			wait_event(mddev->recovery_wait,
 				   atomic_read(&mddev->recovery_active) == 0);
-			mddev->curr_resync_completed =
-				mddev->curr_resync;
+			mddev->curr_resync_completed = j;
 			set_bit(MD_CHANGE_CLEAN, &mddev->flags);
 			sysfs_notify(&mddev->kobj, NULL, "sync_completed");
 		}