+/*
+ * validate_rebuild_devices
+ * @rs
+ *
+ * Determine if the devices specified for rebuild can result in a valid
+ * usable array that is capable of rebuilding the given devices.
+ *
+ * Returns: 0 on success, -EINVAL on failure.
+ */
+static int validate_rebuild_devices(struct raid_set *rs)
+{
+ unsigned i, rebuild_cnt = 0;
+ unsigned rebuilds_per_group, copies, d;
+
+ if (!(rs->print_flags & DMPF_REBUILD))
+ return 0;
+
+ for (i = 0; i < rs->md.raid_disks; i++)
+ if (!test_bit(In_sync, &rs->dev[i].rdev.flags))
+ rebuild_cnt++;
+
+ switch (rs->raid_type->level) {
+ case 1:
+ if (rebuild_cnt >= rs->md.raid_disks)
+ goto too_many;
+ break;
+ case 4:
+ case 5:
+ case 6:
+ if (rebuild_cnt > rs->raid_type->parity_devs)
+ goto too_many;
+ break;
+ case 10:
+ copies = raid10_md_layout_to_copies(rs->md.layout);
+ if (rebuild_cnt < copies)
+ break;
+
+ /*
+ * It is possible to have a higher rebuild count for RAID10,
+ * as long as the failed devices occur in different mirror
+ * groups (i.e. different stripes).
+ *
+ * Right now, we only allow for "near" copies. When other
+ * formats are added, we will have to check those too.
+ *
+ * When checking "near" format, make sure no adjacent devices
+ * have failed beyond what can be handled. In addition to the
+ * simple case where the number of devices is a multiple of the
+ * number of copies, we must also handle cases where the number
+ * of devices is not a multiple of the number of copies.
+ * E.g. dev1 dev2 dev3 dev4 dev5
+ * A A B B C
+ * C D D E E
+ */
+ rebuilds_per_group = 0;
+ for (i = 0; i < rs->md.raid_disks * copies; i++) {
+ d = i % rs->md.raid_disks;
+ if (!test_bit(In_sync, &rs->dev[d].rdev.flags) &&
+ (++rebuilds_per_group >= copies))
+ goto too_many;
+ if (!((i + 1) % copies))
+ rebuilds_per_group = 0;
+ }
+ break;
+ default:
+ DMERR("The rebuild parameter is not supported for %s",
+ rs->raid_type->name);
+ rs->ti->error = "Rebuild not supported for this RAID type";
+ return -EINVAL;
+ }
+
+ return 0;
+
+too_many:
+ rs->ti->error = "Too many rebuild devices specified";
+ return -EINVAL;
+}
+