/*
     md_k.h : kernel internal structure of the Linux MD driver
            Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman
  	  
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; either version 2, or (at your option)
     any later version.
     
     You should have received a copy of the GNU General Public License
     (for example /usr/src/linux/COPYING); if not, write to the Free
     Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  
  */

  #ifndef _MD_MD_H
  #define _MD_MD_H
  
  #include <linux/blkdev.h>
  #include <linux/kobject.h>
  #include <linux/list.h>
  #include <linux/mm.h>
  #include <linux/mutex.h>
  #include <linux/timer.h>
  #include <linux/wait.h>
  #include <linux/workqueue.h>

  #define MaxSector (~(sector_t)0)

  typedef struct mddev_s mddev_t;
  typedef struct mdk_rdev_s mdk_rdev_t;

  /* generic plugging support - like that provided with request_queue,
   * but does not require a request_queue
   */
  struct plug_handle {
  	void			(*unplug_fn)(struct plug_handle *);
  	struct timer_list	unplug_timer;
  	struct work_struct	unplug_work;
  	unsigned long		unplug_flag;
  };
  #define	PLUGGED_FLAG 1
  void plugger_init(struct plug_handle *plug,
  		  void (*unplug_fn)(struct plug_handle *));
  void plugger_set_plug(struct plug_handle *plug);
  int plugger_remove_plug(struct plug_handle *plug);
  static inline void plugger_flush(struct plug_handle *plug)
  {
  	del_timer_sync(&plug->unplug_timer);
  	cancel_work_sync(&plug->unplug_work);
  }

  /*

   * MD's 'extended' device
   */
  struct mdk_rdev_s
  {
  	struct list_head same_set;	/* RAID devices within the same set */

  	sector_t sectors;		/* Device size (in 512bytes sectors) */

  	mddev_t *mddev;			/* RAID array if running */

  	int last_events;		/* IO event timestamp */

  
  	struct block_device *bdev;	/* block device handle */
  
  	struct page	*sb_page;
  	int		sb_loaded;

  	__u64		sb_events;

  	sector_t	data_offset;	/* start of data in array */

  	sector_t 	sb_start;	/* offset of the super block (in 512byte sectors) */

  	int		sb_size;	/* bytes in the superblock */

  	int		preferred_minor;	/* autorun support */

  	struct kobject	kobj;

  	/* A device can be in one of three states based on two flags:
  	 * Not working:   faulty==1 in_sync==0
  	 * Fully working: faulty==0 in_sync==1
  	 * Working, but not
  	 * in sync with array
  	 *                faulty==0 in_sync==0
  	 *
  	 * It can never have faulty==1, in_sync==1
  	 * This reduces the burden of testing multiple flags in many cases
  	 */

  	unsigned long	flags;
  #define	Faulty		1		/* device is known to have a fault */
  #define	In_sync		2		/* device is in_sync with rest of array */

  #define	WriteMostly	4		/* Avoid reading if at all possible */

  #define	BarriersNotsupp	5		/* REQ_HARDBARRIER is not supported */

  #define	AllReserved	6		/* If whole device is reserved for
  					 * one array */

  #define	AutoDetected	7		/* added by auto-detect */

  #define Blocked		8		/* An error occured on an externally
  					 * managed array, don't allow writes
  					 * until it is cleared */
  	wait_queue_head_t blocked_wait;

  	int desc_nr;			/* descriptor index in the superblock */
  	int raid_disk;			/* role of device in array */

  	int new_raid_disk;		/* role that the device will have in
  					 * the array after a level-change completes.
  					 */

  	int saved_raid_disk;		/* role that device used to have in the
  					 * array and could again if we did a partial
  					 * resync from the bitmap
  					 */

  	sector_t	recovery_offset;/* If this device has been partially
  					 * recovered, this is where we were
  					 * up to.
  					 */

  
  	atomic_t	nr_pending;	/* number of pending requests.
  					 * only maintained for arrays that
  					 * support hot removal
  					 */

  	atomic_t	read_errors;	/* number of consecutive read errors that
  					 * we have tried to ignore.
  					 */

  	struct timespec last_read_error;	/* monotonic time since our
  						 * last read error
  						 */

  	atomic_t	corrected_errors; /* number of corrected read errors,
  					   * for reporting to userspace and storing
  					   * in superblock.
  					   */

  	struct work_struct del_work;	/* used for delayed sysfs removal */

  
  	struct sysfs_dirent *sysfs_state; /* handle for 'state'
  					   * sysfs entry */

  };

  struct mddev_s
  {
  	void				*private;

  	struct mdk_personality		*pers;

  	dev_t				unit;
  	int				md_minor;
  	struct list_head 		disks;

  	unsigned long			flags;
  #define MD_CHANGE_DEVS	0	/* Some device status has changed */
  #define MD_CHANGE_CLEAN 1	/* transition to or from 'clean' */

  #define MD_CHANGE_PENDING 2	/* switch from 'clean' to 'active' in progress */

  	int				suspended;
  	atomic_t			active_io;

  	int				ro;

  	int				sysfs_active; /* set when sysfs deletes
  						       * are happening, so run/
  						       * takeover/stop are not safe
  						       */

  
  	struct gendisk			*gendisk;

  	struct kobject			kobj;

  	int				hold_active;
  #define	UNTIL_IOCTL	1

  #define	UNTIL_STOP	2

  	/* Superblock information */
  	int				major_version,
  					minor_version,
  					patch_version;
  	int				persistent;

  	int 				external;	/* metadata is
  							 * managed externally */
  	char				metadata_type[17]; /* externally set*/

  	int				chunk_sectors;

  	time_t				ctime, utime;
  	int				level, layout;

  	char				clevel[16];

  	int				raid_disks;
  	int				max_disks;

  	sector_t			dev_sectors; 	/* used size of
  							 * component devices */

  	sector_t			array_sectors; /* exported array size */

  	int				external_size; /* size managed
  							* externally */

  	__u64				events;

  	/* If the last 'event' was simply a clean->dirty transition, and
  	 * we didn't write it to the spares, then it is safe and simple
  	 * to just decrement the event count on a dirty->clean transition.
  	 * So we record that possibility here.
  	 */
  	int				can_decrease_events;

  
  	char				uuid[16];

  	/* If the array is being reshaped, we need to record the
  	 * new shape and an indication of where we are up to.
  	 * This is written to the superblock.
  	 * If reshape_position is MaxSector, then no reshape is happening (yet).
  	 */
  	sector_t			reshape_position;

  	int				delta_disks, new_level, new_layout;
  	int				new_chunk_sectors;

  	struct mdk_thread_s		*thread;	/* management thread */
  	struct mdk_thread_s		*sync_thread;	/* doing resync or reconstruct */

  	sector_t			curr_resync;	/* last block scheduled */

  	/* As resync requests can complete out of order, we cannot easily track
  	 * how much resync has been completed.  So we occasionally pause until
  	 * everything completes, then set curr_resync_completed to curr_resync.
  	 * As such it may be well behind the real resync mark, but it is a value
  	 * we are certain of.
  	 */
  	sector_t			curr_resync_completed;

  	unsigned long			resync_mark;	/* a recent timestamp */
  	sector_t			resync_mark_cnt;/* blocks written at resync_mark */

  	sector_t			curr_mark_cnt; /* blocks scheduled now */

  
  	sector_t			resync_max_sectors; /* may be set by personality */

  
  	sector_t			resync_mismatches; /* count of sectors where
  							    * parity/replica mismatch found
  							    */

  
  	/* allow user-space to request suspension of IO to regions of the array */
  	sector_t			suspend_lo;
  	sector_t			suspend_hi;

  	/* if zero, use the system-wide default */
  	int				sync_speed_min;
  	int				sync_speed_max;

  	/* resync even though the same disks are shared among md-devices */
  	int				parallel_resync;

  	int				ok_start_degraded;

  	/* recovery/resync flags 
  	 * NEEDED:   we might need to start a resync/recover
  	 * RUNNING:  a thread is running, or about to be started
  	 * SYNC:     actually doing a resync, not a recovery

  	 * RECOVER:  doing recovery, or need to try it.

  	 * INTR:     resync needs to be aborted for some reason

  	 * DONE:     thread is done and is waiting to be reaped

  	 * REQUEST:  user-space has requested a sync (used with SYNC)

  	 * CHECK:    user-space request for check-only, no repair

  	 * RESHAPE:  A reshape is happening
  	 *
  	 * If neither SYNC or RESHAPE are set, then it is a recovery.

  	 */
  #define	MD_RECOVERY_RUNNING	0
  #define	MD_RECOVERY_SYNC	1

  #define	MD_RECOVERY_RECOVER	2

  #define	MD_RECOVERY_INTR	3
  #define	MD_RECOVERY_DONE	4
  #define	MD_RECOVERY_NEEDED	5

  #define	MD_RECOVERY_REQUESTED	6
  #define	MD_RECOVERY_CHECK	7

  #define MD_RECOVERY_RESHAPE	8

  #define	MD_RECOVERY_FROZEN	9

  	unsigned long			recovery;

  	int				recovery_disabled; /* if we detect that recovery
  							    * will always fail, set this
  							    * so we don't loop trying */

  
  	int				in_sync;	/* know to not need resync */

  	/* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
  	 * that we are never stopping an array while it is open.
  	 * 'reconfig_mutex' protects all other reconfiguration.
  	 * These locks are separate due to conflicting interactions
  	 * with bdev->bd_mutex.
  	 * Lock ordering is:
  	 *  reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
  	 *  bd_mutex -> open_mutex:  e.g. __blkdev_get -> md_open
  	 */
  	struct mutex			open_mutex;

  	struct mutex			reconfig_mutex;

  	atomic_t			active;		/* general refcount */
  	atomic_t			openers;	/* number of active opens */

  	int				degraded;	/* whether md should consider
  							 * adding a spare
  							 */

  	int				barriers_work;	/* initialised to true, cleared as soon
  							 * as a barrier request to slave
  							 * fails.  Only supported
  							 */
  	struct bio			*biolist; 	/* bios that need to be retried

  							 * because REQ_HARDBARRIER is not supported

  							 */

  
  	atomic_t			recovery_active; /* blocks scheduled, but not written */
  	wait_queue_head_t		recovery_wait;
  	sector_t			recovery_cp;

  	sector_t			resync_min;	/* user requested sync
  							 * starts here */

  	sector_t			resync_max;	/* resync should pause
  							 * when it gets here */

  	struct sysfs_dirent		*sysfs_state;	/* handle for 'array_state'
  							 * file in sysfs.
  							 */

  	struct sysfs_dirent		*sysfs_action;  /* handle for 'sync_action' */

  	struct work_struct del_work;	/* used for delayed sysfs removal */

  	spinlock_t			write_lock;

  	wait_queue_head_t		sb_wait;	/* for waiting on superblock updates */

  	atomic_t			pending_writes;	/* number of active superblock writes */

  	unsigned int			safemode;	/* if set, update "clean" superblock
  							 * when no writes pending.
  							 */ 
  	unsigned int			safemode_delay;
  	struct timer_list		safemode_timer;
  	atomic_t			writes_pending; 

  	struct request_queue		*queue;	/* for plugging ... */

  	struct bitmap                   *bitmap; /* the bitmap for the device */

  	struct {
  		struct file		*file; /* the bitmap file */

  		loff_t			offset; /* offset from superblock of

  						 * start of bitmap. May be
  						 * negative, but not '0'

  						 * For external metadata, offset
  						 * from start of device. 

  						 */

  		loff_t			default_offset; /* this is the offset to use when

  							 * hot-adding a bitmap.  It should
  							 * eventually be settable by sysfs.
  							 */

  		/* When md is serving under dm, it might use a
  		 * dirty_log to store the bits.
  		 */
  		struct dm_dirty_log *log;

  		struct mutex		mutex;

  		unsigned long		chunksize;

  		unsigned long		daemon_sleep; /* how many jiffies between updates? */

  		unsigned long		max_write_behind; /* write-behind mode */

  		int			external;

  	} bitmap_info;

  	atomic_t 			max_corr_read_errors; /* max read retries */

  	struct list_head		all_mddevs;

  	struct attribute_group		*to_remove;

  	struct plug_handle		*plug; /* if used by personality */

  	/* Generic barrier handling.
  	 * If there is a pending barrier request, all other
  	 * writes are blocked while the devices are flushed.
  	 * The last to finish a flush schedules a worker to
  	 * submit the barrier request (without the barrier flag),
  	 * then submit more flush requests.
  	 */
  	struct bio *barrier;
  	atomic_t flush_pending;
  	struct work_struct barrier_work;

  	struct work_struct event_work;	/* used by dm to report failure event */

  };
  
  
  static inline void rdev_dec_pending(mdk_rdev_t *rdev, mddev_t *mddev)
  {

  	int faulty = test_bit(Faulty, &rdev->flags);

  	if (atomic_dec_and_test(&rdev->nr_pending) && faulty)
  		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
  }
  
  static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
  {
          atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
  }

  struct mdk_personality

  {
  	char *name;

  	int level;
  	struct list_head list;

  	struct module *owner;

  	int (*make_request)(mddev_t *mddev, struct bio *bio);

  	int (*run)(mddev_t *mddev);
  	int (*stop)(mddev_t *mddev);
  	void (*status)(struct seq_file *seq, mddev_t *mddev);
  	/* error_handler must set ->faulty and clear ->in_sync
  	 * if appropriate, and should abort recovery if needed 
  	 */
  	void (*error_handler)(mddev_t *mddev, mdk_rdev_t *rdev);
  	int (*hot_add_disk) (mddev_t *mddev, mdk_rdev_t *rdev);
  	int (*hot_remove_disk) (mddev_t *mddev, int number);
  	int (*spare_active) (mddev_t *mddev);

  	sector_t (*sync_request)(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster);

  	int (*resize) (mddev_t *mddev, sector_t sectors);

  	sector_t (*size) (mddev_t *mddev, sector_t sectors, int raid_disks);

  	int (*check_reshape) (mddev_t *mddev);
  	int (*start_reshape) (mddev_t *mddev);

  	void (*finish_reshape) (mddev_t *mddev);

  	/* quiesce moves between quiescence states
  	 * 0 - fully active
  	 * 1 - no new requests allowed
  	 * others - reserved
  	 */
  	void (*quiesce) (mddev_t *mddev, int state);

  	/* takeover is used to transition an array from one
  	 * personality to another.  The new personality must be able
  	 * to handle the data in the current layout.
  	 * e.g. 2drive raid1 -> 2drive raid5
  	 *      ndrive raid5 -> degraded n+1drive raid6 with special layout
  	 * If the takeover succeeds, a new 'private' structure is returned.
  	 * This needs to be installed and then ->run used to activate the
  	 * array.
  	 */
  	void *(*takeover) (mddev_t *mddev);

  };

  struct md_sysfs_entry {
  	struct attribute attr;
  	ssize_t (*show)(mddev_t *, char *);
  	ssize_t (*store)(mddev_t *, const char *, size_t);
  };

  extern struct attribute_group md_bitmap_group;

  static inline struct sysfs_dirent *sysfs_get_dirent_safe(struct sysfs_dirent *sd, char *name)
  {
  	if (sd)
  		return sysfs_get_dirent(sd, NULL, name);
  	return sd;
  }
  static inline void sysfs_notify_dirent_safe(struct sysfs_dirent *sd)
  {
  	if (sd)
  		sysfs_notify_dirent(sd);
  }

  static inline char * mdname (mddev_t * mddev)
  {
  	return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
  }

  /*
   * iterates through some rdev ringlist. It's safe to remove the
   * current 'rdev'. Dont touch 'tmp' though.
   */

  #define rdev_for_each_list(rdev, tmp, head)				\
  	list_for_each_entry_safe(rdev, tmp, head, same_set)

  /*
   * iterates through the 'same array disks' ringlist
   */

  #define rdev_for_each(rdev, tmp, mddev)				\

  	list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)

  #define rdev_for_each_rcu(rdev, mddev)				\
  	list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)

  typedef struct mdk_thread_s {
  	void			(*run) (mddev_t *mddev);
  	mddev_t			*mddev;
  	wait_queue_head_t	wqueue;
  	unsigned long           flags;

  	struct task_struct	*tsk;

  	unsigned long		timeout;

  } mdk_thread_t;
  
  #define THREAD_WAKEUP  0
  
  #define __wait_event_lock_irq(wq, condition, lock, cmd) 		\
  do {									\
  	wait_queue_t __wait;						\
  	init_waitqueue_entry(&__wait, current);				\
  									\
  	add_wait_queue(&wq, &__wait);					\
  	for (;;) {							\
  		set_current_state(TASK_UNINTERRUPTIBLE);		\
  		if (condition)						\
  			break;						\
  		spin_unlock_irq(&lock);					\
  		cmd;							\
  		schedule();						\
  		spin_lock_irq(&lock);					\
  	}								\
  	current->state = TASK_RUNNING;					\
  	remove_wait_queue(&wq, &__wait);				\
  } while (0)
  
  #define wait_event_lock_irq(wq, condition, lock, cmd) 			\
  do {									\
  	if (condition)	 						\
  		break;							\
  	__wait_event_lock_irq(wq, condition, lock, cmd);		\
  } while (0)

  static inline void safe_put_page(struct page *p)
  {
  	if (p) put_page(p);
  }

  extern int register_md_personality(struct mdk_personality *p);
  extern int unregister_md_personality(struct mdk_personality *p);
  extern mdk_thread_t * md_register_thread(void (*run) (mddev_t *mddev),
  				mddev_t *mddev, const char *name);
  extern void md_unregister_thread(mdk_thread_t *thread);
  extern void md_wakeup_thread(mdk_thread_t *thread);
  extern void md_check_recovery(mddev_t *mddev);
  extern void md_write_start(mddev_t *mddev, struct bio *bi);
  extern void md_write_end(mddev_t *mddev);
  extern void md_done_sync(mddev_t *mddev, int blocks, int ok);
  extern void md_error(mddev_t *mddev, mdk_rdev_t *rdev);

  extern int mddev_congested(mddev_t *mddev, int bits);

  extern void md_barrier_request(mddev_t *mddev, struct bio *bio);

  extern void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
  			   sector_t sector, int size, struct page *page);
  extern void md_super_wait(mddev_t *mddev);
  extern int sync_page_io(struct block_device *bdev, sector_t sector, int size,
  			struct page *page, int rw);
  extern void md_do_sync(mddev_t *mddev);
  extern void md_new_event(mddev_t *mddev);
  extern int md_allow_write(mddev_t *mddev);
  extern void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev);

  extern void md_set_array_sectors(mddev_t *mddev, sector_t array_sectors);

  extern int md_check_no_bitmap(mddev_t *mddev);

  extern int md_integrity_register(mddev_t *mddev);

  extern void md_integrity_add_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
  extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);

  extern void restore_bitmap_write_access(struct file *file);

  extern void md_unplug(mddev_t *mddev);

  extern void mddev_init(mddev_t *mddev);
  extern int md_run(mddev_t *mddev);
  extern void md_stop(mddev_t *mddev);
  extern void md_stop_writes(mddev_t *mddev);

  extern void md_rdev_init(mdk_rdev_t *rdev);

  extern void mddev_suspend(mddev_t *mddev);
  extern void mddev_resume(mddev_t *mddev);

  #endif /* _MD_MD_H */