+/*
+ * Need to check if array has failed when deciding whether to:
+ * - start an array
+ * - remove non-faulty devices
+ * - add a spare
+ * - allow a reshape
+ * This determination is simple when no reshape is happening.
+ * However if there is a reshape, we need to carefully check
+ * both the before and after sections.
+ * This is because some failed devices may only affect one
+ * of the two sections, and some non-in_sync devices may
+ * be insync in the section most affected by failed devices.
+ */
+static int has_failed(raid5_conf_t *conf)
+{
+ int degraded;
+ int i;
+ if (conf->mddev->reshape_position == MaxSector)
+ return conf->mddev->degraded > conf->max_degraded;
+
+ rcu_read_lock();
+ degraded = 0;
+ for (i = 0; i < conf->previous_raid_disks; i++) {
+ mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
+ if (!rdev || test_bit(Faulty, &rdev->flags))
+ degraded++;
+ else if (test_bit(In_sync, &rdev->flags))
+ ;
+ else
+ /* not in-sync or faulty.
+ * If the reshape increases the number of devices,
+ * this is being recovered by the reshape, so
+ * this 'previous' section is not in_sync.
+ * If the number of devices is being reduced however,
+ * the device can only be part of the array if
+ * we are reverting a reshape, so this section will
+ * be in-sync.
+ */
+ if (conf->raid_disks >= conf->previous_raid_disks)
+ degraded++;
+ }
+ rcu_read_unlock();
+ if (degraded > conf->max_degraded)
+ return 1;
+ rcu_read_lock();
+ degraded = 0;
+ for (i = 0; i < conf->raid_disks; i++) {
+ mdk_rdev_t *rdev = rcu_dereference(conf->disks[i].rdev);
+ if (!rdev || test_bit(Faulty, &rdev->flags))
+ degraded++;
+ else if (test_bit(In_sync, &rdev->flags))
+ ;
+ else
+ /* not in-sync or faulty.
+ * If reshape increases the number of devices, this
+ * section has already been recovered, else it
+ * almost certainly hasn't.
+ */
+ if (conf->raid_disks <= conf->previous_raid_disks)
+ degraded++;
+ }
+ rcu_read_unlock();
+ if (degraded > conf->max_degraded)
+ return 1;
+ return 0;
+}
+