* pool was allocated for, so they know how much to allocate and free.
* mddev->raid_disks cannot be used, as it can change while a pool is active
* These two datums are stored in a kmalloced struct.
+ * The 'raid_disks' here is twice the raid_disks in r1conf.
+ * This allows space for each 'real' device can have a replacement in the
+ * second half of the array.
*/
struct pool_info {
struct r1conf {
struct mddev *mddev;
- struct mirror_info *mirrors;
+ struct mirror_info *mirrors; /* twice 'raid_disks' to
+ * allow for replacements.
+ */
int raid_disks;
/* When choose the best device for a read (read_balance())