md: don't reset curr_resync_completed after an interrupted resync

If a resync/recovery/check/repair is interrupted for some reason, it
can be useful to know exactly where it got up to.
So in that case, do not clear curr_resync_completed.
Initialise it when starting a resync/recovery/... instead.
Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/md.c

@@ -6381,6 +6381,7 @@ void md_do_sync(mddev_t *mddev)
 		       desc, mdname(mddev));
 		mddev->curr_resync = j;
 	}
+	mddev->curr_resync_completed = mddev->curr_resync;
 
 	while (j < max_sectors) {
 		sector_t sectors;
@@ -6532,7 +6533,8 @@ void md_do_sync(mddev_t *mddev)
 	} else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
 		mddev->resync_min = mddev->curr_resync_completed;
 	mddev->curr_resync = 0;
-	mddev->curr_resync_completed = 0;
+	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+		mddev->curr_resync_completed = 0;
 	sysfs_notify(&mddev->kobj, NULL, "sync_completed");
 	wake_up(&resync_wait);
 	set_bit(MD_RECOVERY_DONE, &mddev->recovery);