+#ifdef CONFIG_MD_RAID5_RESHAPE
+static int raid5_check_reshape(mddev_t *mddev)
+{
+ raid5_conf_t *conf = mddev_to_conf(mddev);
+ int err;
+
+ if (mddev->delta_disks < 0 ||
+ mddev->new_level != mddev->level)
+ return -EINVAL; /* Cannot shrink array or change level yet */
+ if (mddev->delta_disks == 0)
+ return 0; /* nothing to do */
+
+ /* Can only proceed if there are plenty of stripe_heads.
+ * We need a minimum of one full stripe,, and for sensible progress
+ * it is best to have about 4 times that.
+ * If we require 4 times, then the default 256 4K stripe_heads will
+ * allow for chunk sizes up to 256K, which is probably OK.
+ * If the chunk size is greater, user-space should request more
+ * stripe_heads first.
+ */
+ if ((mddev->chunk_size / STRIPE_SIZE) * 4 > conf->max_nr_stripes ||
+ (mddev->new_chunk / STRIPE_SIZE) * 4 > conf->max_nr_stripes) {
+ printk(KERN_WARNING "raid5: reshape: not enough stripes. Needed %lu\n",
+ (mddev->chunk_size / STRIPE_SIZE)*4);
+ return -ENOSPC;
+ }
+
+ err = resize_stripes(conf, conf->raid_disks + mddev->delta_disks);
+ if (err)
+ return err;
+
+ /* looks like we might be able to manage this */
+ return 0;
+}
+
+static int raid5_start_reshape(mddev_t *mddev)
+{
+ raid5_conf_t *conf = mddev_to_conf(mddev);
+ mdk_rdev_t *rdev;
+ struct list_head *rtmp;
+ int spares = 0;
+ int added_devices = 0;
+
+ if (mddev->degraded ||
+ test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+ return -EBUSY;
+
+ ITERATE_RDEV(mddev, rdev, rtmp)
+ if (rdev->raid_disk < 0 &&
+ !test_bit(Faulty, &rdev->flags))
+ spares++;
+
+ if (spares < mddev->delta_disks-1)
+ /* Not enough devices even to make a degraded array
+ * of that size
+ */
+ return -EINVAL;
+
+ atomic_set(&conf->reshape_stripes, 0);
+ spin_lock_irq(&conf->device_lock);
+ conf->previous_raid_disks = conf->raid_disks;
+ conf->raid_disks += mddev->delta_disks;
+ conf->expand_progress = 0;
+ conf->expand_lo = 0;
+ spin_unlock_irq(&conf->device_lock);
+
+ /* Add some new drives, as many as will fit.
+ * We know there are enough to make the newly sized array work.
+ */
+ ITERATE_RDEV(mddev, rdev, rtmp)
+ if (rdev->raid_disk < 0 &&
+ !test_bit(Faulty, &rdev->flags)) {
+ if (raid5_add_disk(mddev, rdev)) {
+ char nm[20];
+ set_bit(In_sync, &rdev->flags);
+ conf->working_disks++;
+ added_devices++;
+ sprintf(nm, "rd%d", rdev->raid_disk);
+ sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
+ } else
+ break;
+ }
+
+ mddev->degraded = (conf->raid_disks - conf->previous_raid_disks) - added_devices;
+ mddev->raid_disks = conf->raid_disks;
+ mddev->reshape_position = 0;
+ mddev->sb_dirty = 1;
+
+ clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+ clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+ set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
+ set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+ mddev->sync_thread = md_register_thread(md_do_sync, mddev,
+ "%s_reshape");
+ if (!mddev->sync_thread) {
+ mddev->recovery = 0;
+ spin_lock_irq(&conf->device_lock);
+ mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
+ conf->expand_progress = MaxSector;
+ spin_unlock_irq(&conf->device_lock);
+ return -EAGAIN;
+ }
+ md_wakeup_thread(mddev->sync_thread);
+ md_new_event(mddev);
+ return 0;
+}
+#endif
+
+static void end_reshape(raid5_conf_t *conf)
+{
+ struct block_device *bdev;
+
+ if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
+ conf->mddev->array_size = conf->mddev->size * (conf->raid_disks-1);
+ set_capacity(conf->mddev->gendisk, conf->mddev->array_size << 1);
+ conf->mddev->changed = 1;
+
+ bdev = bdget_disk(conf->mddev->gendisk, 0);
+ if (bdev) {
+ mutex_lock(&bdev->bd_inode->i_mutex);
+ i_size_write(bdev->bd_inode, conf->mddev->array_size << 10);
+ mutex_unlock(&bdev->bd_inode->i_mutex);
+ bdput(bdev);
+ }
+ spin_lock_irq(&conf->device_lock);
+ conf->expand_progress = MaxSector;
+ spin_unlock_irq(&conf->device_lock);
+ conf->mddev->reshape_position = MaxSector;
+ }
+}
+
+static void raid5_quiesce(mddev_t *mddev, int state)
+{
+ raid5_conf_t *conf = mddev_to_conf(mddev);
+
+ switch(state) {
+ case 2: /* resume for a suspend */
+ wake_up(&conf->wait_for_overlap);
+ break;
+
+ case 1: /* stop all writes */
+ spin_lock_irq(&conf->device_lock);
+ conf->quiesce = 1;
+ wait_event_lock_irq(conf->wait_for_stripe,
+ atomic_read(&conf->active_stripes) == 0,
+ conf->device_lock, /* nothing */);
+ spin_unlock_irq(&conf->device_lock);
+ break;
+
+ case 0: /* re-enable writes */
+ spin_lock_irq(&conf->device_lock);
+ conf->quiesce = 0;
+ wake_up(&conf->wait_for_stripe);
+ wake_up(&conf->wait_for_overlap);
+ spin_unlock_irq(&conf->device_lock);
+ break;
+ }
+}
+
+static struct mdk_personality raid5_personality =