#ifndef _RAID10_H
  #define _RAID10_H

  typedef struct mirror_info mirror_info_t;
  
  struct mirror_info {
  	mdk_rdev_t	*rdev;
  	sector_t	head_position;
  };
  
  typedef struct r10bio_s r10bio_t;
  
  struct r10_private_data_s {
  	mddev_t			*mddev;
  	mirror_info_t		*mirrors;
  	int			raid_disks;

  	spinlock_t		device_lock;
  
  	/* geometry */
  	int			near_copies;  /* number of copies layed out raid0 style */
  	int 			far_copies;   /* number of copies layed out
  					       * at large strides across drives
  					       */

  	int			far_offset;   /* far_copies are offset by 1 stripe
  					       * instead of many
  					       */

  	int			copies;	      /* near_copies * far_copies.
  					       * must be <= raid_disks
  					       */
  	sector_t		stride;	      /* distance between far copies.

  					       * This is size / far_copies unless
  					       * far_offset, in which case it is
  					       * 1 stripe.

  					       */

  	sector_t		dev_sectors;  /* temp copy of mddev->dev_sectors */

  	int chunk_shift; /* shift from chunks to sectors */
  	sector_t chunk_mask;
  
  	struct list_head	retry_list;

  	/* queue pending writes and submit them on unplug */
  	struct bio_list		pending_bio_list;

  
  	spinlock_t		resync_lock;
  	int nr_pending;

  	int nr_waiting;

  	int nr_queued;

  	int barrier;
  	sector_t		next_resync;

  	int			fullsync;  /* set to 1 if a full sync is needed,
  					    * (fresh device added).
  					    * Cleared when a sync completes.
  					    */

  	wait_queue_head_t	wait_barrier;

  
  	mempool_t *r10bio_pool;
  	mempool_t *r10buf_pool;

  	struct page		*tmppage;

  
  	/* When taking over an array from a different personality, we store
  	 * the new thread here until we fully activate the array.
  	 */
  	struct mdk_thread_s	*thread;

  };
  
  typedef struct r10_private_data_s conf_t;
  
  /*

   * this is our 'private' RAID10 bio.
   *
   * it contains information about what kind of IO operations were started
   * for this RAID10 operation, and about their status:
   */
  
  struct r10bio_s {
  	atomic_t		remaining; /* 'have we finished' count,
  					    * used from IRQ handlers
  					    */
  	sector_t		sector;	/* virtual sector number */
  	int			sectors;
  	unsigned long		state;
  	mddev_t			*mddev;
  	/*
  	 * original bio going to /dev/mdx
  	 */
  	struct bio		*master_bio;
  	/*
  	 * if the IO is in READ direction, then this is where we read
  	 */
  	int			read_slot;
  
  	struct list_head	retry_list;
  	/*
  	 * if the IO is in WRITE direction, then multiple bios are used,
  	 * one for each copy.
  	 * When resyncing we also use one for each copy.
  	 * When reconstructing, we use 2 bios, one for read, one for write.
  	 * We choose the number when they are allocated.
  	 */
  	struct {
  		struct bio		*bio;
  		sector_t addr;
  		int devnum;
  	} devs[0];
  };

  /* when we get a read error on a read-only array, we redirect to another
   * device without failing the first device, or trying to over-write to
   * correct the read error.  To keep track of bad blocks on a per-bio
   * level, we store IO_BLOCKED in the appropriate 'bios' pointer
   */
  #define IO_BLOCKED ((struct bio*)1)

  /* bits for r10bio.state */
  #define	R10BIO_Uptodate	0
  #define	R10BIO_IsSync	1
  #define	R10BIO_IsRecover 2

  #define	R10BIO_Degraded 3

  #endif