#ifndef _RAID10_H
  #define _RAID10_H

  struct mirror_info {

  	struct md_rdev	*rdev, *replacement;

  	sector_t	head_position;

  	int		recovery_disabled;	/* matches
  						 * mddev->recovery_disabled
  						 * when we shouldn't try
  						 * recovering this device.
  						 */

  };

  struct r10conf {

  	struct mddev		*mddev;

  	struct mirror_info	*mirrors;

  	int			raid_disks;

  	spinlock_t		device_lock;
  
  	/* geometry */

  	int			near_copies;  /* number of copies laid out
  					       * raid0 style */

  	int 			far_copies;   /* number of copies laid 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;

  	int			pending_count;

  
  	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.
  					    */

  	int			have_replacement; /* There is at least one
  						   * replacement device.
  						   */

  	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 md_thread	*thread;

  };

  /*

   * 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 {

  	atomic_t		remaining; /* 'have we finished' count,
  					    * used from IRQ handlers
  					    */
  	sector_t		sector;	/* virtual sector number */
  	int			sectors;
  	unsigned long		state;

  	struct mddev		*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.

  	 * We sometimes need an extra bio to write to the replacement.

  	 */
  	struct {

  		struct bio	*bio;
  		union {
  			struct bio	*repl_bio; /* used for resync and
  						    * writes */
  			struct md_rdev	*rdev;	   /* used for reads
  						    * (read_slot >= 0) */
  		};
  		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)

  /* When we successfully write to a known bad-block, we need to remove the
   * bad-block marking which must be done from process context.  So we record
   * the success by setting devs[n].bio to IO_MADE_GOOD
   */
  #define IO_MADE_GOOD ((struct bio *)2)
  
  #define BIO_SPECIAL(bio) ((unsigned long)bio <= 2)

  /* bits for r10bio.state */

  enum r10bio_state {
  	R10BIO_Uptodate,
  	R10BIO_IsSync,
  	R10BIO_IsRecover,
  	R10BIO_Degraded,

  /* Set ReadError on bios that experience a read error
   * so that raid10d knows what to do with them.
   */

  	R10BIO_ReadError,

  /* If a write for this request means we can clear some
   * known-bad-block records, we set this flag.
   */

  	R10BIO_MadeGood,
  	R10BIO_WriteError,
  };

  #endif