#ifndef _RAID5_H

#define _RAID5_H

#include <linux/raid/md.h>

#include <linux/raid/xor.h>

/*

 *

 * Each stripe contains one buffer per disc.  Each buffer can be in

 * one of a number of states stored in "flags".  Changes between

 * these states happen *almost* exclusively under a per-stripe

 * spinlock.  Some very specific changes can happen in bi_end_io, and

 * these are not protected by the spin lock.

 *

 * The flag bits that are used to represent these states are:

 *   R5_UPTODATE and R5_LOCKED

 *

 * State Empty == !UPTODATE, !LOCK

 *        We have no data, and there is no active request

 * State Want == !UPTODATE, LOCK

 *        A read request is being submitted for this block

 * State Dirty == UPTODATE, LOCK

 *        Some new data is in this buffer, and it is being written out

 * State Clean == UPTODATE, !LOCK

 *        We have valid data which is the same as on disc

 *

 * The possible state transitions are:

 *

 *  Empty -> Want   - on read or write to get old data for  parity calc

 *  Empty -> Dirty  - on compute_parity to satisfy write/sync request.(RECONSTRUCT_WRITE)

 *  Empty -> Clean  - on compute_block when computing a block for failed drive

 *  Want  -> Empty  - on failed read

 *  Want  -> Clean  - on successful completion of read request

 *  Dirty -> Clean  - on successful completion of write request

 *  Dirty -> Clean  - on failed write

 *  Clean -> Dirty  - on compute_parity to satisfy write/sync (RECONSTRUCT or RMW)

 *

 * The Want->Empty, Want->Clean, Dirty->Clean, transitions

 * all happen in b_end_io at interrupt time.

 * Each sets the Uptodate bit before releasing the Lock bit.

 * This leaves one multi-stage transition:

 *    Want->Dirty->Clean

 * This is safe because thinking that a Clean buffer is actually dirty

 * will at worst delay some action, and the stripe will be scheduled

 * for attention after the transition is complete.

 *

 * There is one possibility that is not covered by these states.  That

 * is if one drive has failed and there is a spare being rebuilt.  We

 * can't distinguish between a clean block that has been generated

 * from parity calculations, and a clean block that has been

 * successfully written to the spare ( or to parity when resyncing).

 * To distingush these states we have a stripe bit STRIPE_INSYNC that

 * is set whenever a write is scheduled to the spare, or to the parity

 * disc if there is no spare.  A sync request clears this bit, and

 * when we find it set with no buffers locked, we know the sync is

 * complete.

 *

 * Buffers for the md device that arrive via make_request are attached

 * to the appropriate stripe in one of two lists linked on b_reqnext.

 * One list (bh_read) for read requests, one (bh_write) for write.

 * There should never be more than one buffer on the two lists

 * together, but we are not guaranteed of that so we allow for more.

 *

 * If a buffer is on the read list when the associated cache buffer is

 * Uptodate, the data is copied into the read buffer and it's b_end_io

 * routine is called.  This may happen in the end_request routine only

 * if the buffer has just successfully been read.  end_request should

 * remove the buffers from the list and then set the Uptodate bit on

 * the buffer.  Other threads may do this only if they first check

 * that the Uptodate bit is set.  Once they have checked that they may

 * take buffers off the read queue.

 *

 * When a buffer on the write list is committed for write it is copied

 * into the cache buffer, which is then marked dirty, and moved onto a

 * third list, the written list (bh_written).  Once both the parity

 * block and the cached buffer are successfully written, any buffer on

 * a written list can be returned with b_end_io.

 *

 * The write list and read list both act as fifos.  The read list is

 * protected by the device_lock.  The write and written lists are

 * protected by the stripe lock.  The device_lock, which can be

 * claimed while the stipe lock is held, is only for list

 * manipulations and will only be held for a very short time.  It can

 * be claimed from interrupts.

 *

 *

 * Stripes in the stripe cache can be on one of two lists (or on

 * neither).  The "inactive_list" contains stripes which are not

 * currently being used for any request.  They can freely be reused

 * for another stripe.  The "handle_list" contains stripes that need

 * to be handled in some way.  Both of these are fifo queues.  Each

 * stripe is also (potentially) linked to a hash bucket in the hash

 * table so that it can be found by sector number.  Stripes that are

 * not hashed must be on the inactive_list, and will normally be at

 * the front.  All stripes start life this way.

 *

 * The inactive_list, handle_list and hash bucket lists are all protected by the

 * device_lock.

 *  - stripes on the inactive_list never have their stripe_lock held.

 *  - stripes have a reference counter. If count==0, they are on a list.

 *  - If a stripe might need handling, STRIPE_HANDLE is set.

 *  - When refcount reaches zero, then if STRIPE_HANDLE it is put on

 *    handle_list else inactive_list

 *

 * This, combined with the fact that STRIPE_HANDLE is only ever

 * cleared while a stripe has a non-zero count means that if the

 * refcount is 0 and STRIPE_HANDLE is set, then it is on the

 * handle_list and if recount is 0 and STRIPE_HANDLE is not set, then

 * the stripe is on inactive_list.

 *

 * The possible transitions are:

 *  activate an unhashed/inactive stripe (get_active_stripe())

 *     lockdev check-hash unlink-stripe cnt++ clean-stripe hash-stripe unlockdev

 *  activate a hashed, possibly active stripe (get_active_stripe())

 *     lockdev check-hash if(!cnt++)unlink-stripe unlockdev

 *  attach a request to an active stripe (add_stripe_bh())

 *     lockdev attach-buffer unlockdev

 *  handle a stripe (handle_stripe())

 *     lockstripe clrSTRIPE_HANDLE ...

 *		(lockdev check-buffers unlockdev) ..

 *		change-state ..

 *		record io/ops needed unlockstripe schedule io/ops

 *  release an active stripe (release_stripe())

 *     lockdev if (!--cnt) { if  STRIPE_HANDLE, add to handle_list else add to inactive-list } unlockdev

 *

 * The refcount counts each thread that have activated the stripe,

 * plus raid5d if it is handling it, plus one for each active request

 * on a cached buffer, and plus one if the stripe is undergoing stripe

 * operations.

 *

 * Stripe operations are performed outside the stripe lock,

 * the stripe operations are:

 * -copying data between the stripe cache and user application buffers

 * -computing blocks to save a disk access, or to recover a missing block

 * -updating the parity on a write operation (reconstruct write and

 *  read-modify-write)

 * -checking parity correctness

 * -running i/o to disk

 * These operations are carried out by raid5_run_ops which uses the async_tx

 * api to (optionally) offload operations to dedicated hardware engines.

 * When requesting an operation handle_stripe sets the pending bit for the

 * operation and increments the count.  raid5_run_ops is then run whenever

 * the count is non-zero.

 * There are some critical dependencies between the operations that prevent some

 * from being requested while another is in flight.

 * 1/ Parity check operations destroy the in cache version of the parity block,

 *    so we prevent parity dependent operations like writes and compute_blocks

 *    from starting while a check is in progress.  Some dma engines can perform

 *    the check without damaging the parity block, in these cases the parity

 *    block is re-marked up to date (assuming the check was successful) and is

 *    not re-read from disk.

 * 2/ When a write operation is requested we immediately lock the affected

 *    blocks, and mark them as not up to date.  This causes new read requests

 *    to be held off, as well as parity checks and compute block operations.

 * 3/ Once a compute block operation has been requested handle_stripe treats

 *    that block as if it is up to date.  raid5_run_ops guaruntees that any

 *    operation that is dependent on the compute block result is initiated after

 *    the compute block completes.

 */

/*

 * Operations state - intermediate states that are visible outside of sh->lock

 * In general _idle indicates nothing is running, _run indicates a data

 * processing operation is active, and _result means the data processing result

 * is stable and can be acted upon.  For simple operations like biofill and

 * compute that only have an _idle and _run state they are indicated with

 * sh->state flags (STRIPE_BIOFILL_RUN and STRIPE_COMPUTE_RUN)

 */

/**

 * enum check_states - handles syncing / repairing a stripe

 * @check_state_idle - check operations are quiesced

 * @check_state_run - check operation is running

 * @check_state_result - set outside lock when check result is valid

 * @check_state_compute_run - check failed and we are repairing

 * @check_state_compute_result - set outside lock when compute result is valid

 */

enum check_states {

	check_state_idle = 0,

	check_state_run, /* parity check */

	check_state_check_result,

	check_state_compute_run, /* parity repair */

	check_state_compute_result,

};

/**

 * enum reconstruct_states - handles writing or expanding a stripe

 */

enum reconstruct_states {

	reconstruct_state_idle = 0,

	reconstruct_state_prexor_drain_run,	/* prexor-write */

	reconstruct_state_drain_run,		/* write */

	reconstruct_state_run,			/* expand */

	reconstruct_state_prexor_drain_result,

	reconstruct_state_drain_result,

	reconstruct_state_result,

};

struct stripe_head {

	struct hlist_node	hash;

	struct list_head	lru;			/* inactive_list or handle_list */

	struct raid5_private_data	*raid_conf;

	sector_t		sector;			/* sector of this row */

	int			pd_idx;			/* parity disk index */

	unsigned long		state;			/* state flags */

	atomic_t		count;			/* nr of active thread/requests */

	spinlock_t		lock;

	int			bm_seq;	/* sequence number for bitmap flushes */

	int			disks;			/* disks in stripe */

	enum check_states	check_state;

	enum reconstruct_states reconstruct_state;

	/* stripe_operations

	 * @target - STRIPE_OP_COMPUTE_BLK target

	 */

	struct stripe_operations {

		int		   target;

		u32		   zero_sum_result;

	} ops;

	struct r5dev {

		struct bio	req;

		struct bio_vec	vec;

		struct page	*page;

		struct bio	*toread, *read, *towrite, *written;

		sector_t	sector;			/* sector of this page */

		unsigned long	flags;

	} dev[1]; /* allocated with extra space depending of RAID geometry */

};

/* stripe_head_state - collects and tracks the dynamic state of a stripe_head

 *     for handle_stripe.  It is only valid under spin_lock(sh->lock);

 */

struct stripe_head_state {

	int syncing, expanding, expanded;

	int locked, uptodate, to_read, to_write, failed, written;

	int to_fill, compute, req_compute, non_overwrite;

	int failed_num;

	unsigned long ops_request;

};

/* r6_state - extra state data only relevant to r6 */

struct r6_state {

	int p_failed, q_failed, qd_idx, failed_num[2];

};

/* Flags */

#define	R5_UPTODATE	0	/* page contains current data */

#define	R5_LOCKED	1	/* IO has been submitted on "req" */

#define	R5_OVERWRITE	2	/* towrite covers whole page */

/* and some that are internal to handle_stripe */

#define	R5_Insync	3	/* rdev && rdev->in_sync at start */

#define	R5_Wantread	4	/* want to schedule a read */

#define	R5_Wantwrite	5

#define	R5_Overlap	7	/* There is a pending overlapping request on this block */

#define	R5_ReadError	8	/* seen a read error here recently */

#define	R5_ReWrite	9	/* have tried to over-write the readerror */

#define	R5_Expanded	10	/* This block now has post-expand data */

#define	R5_Wantcompute	11 /* compute_block in progress treat as

				    * uptodate

				    */

#define	R5_Wantfill	12 /* dev->toread contains a bio that needs

				    * filling

				    */

#define R5_Wantdrain	13 /* dev->towrite needs to be drained */

/*

 * Write method

 */

#define RECONSTRUCT_WRITE	1

#define READ_MODIFY_WRITE	2

/* not a write method, but a compute_parity mode */

#define	CHECK_PARITY		3

/*

 * Stripe state

 */

#define STRIPE_HANDLE		2

#define	STRIPE_SYNCING		3

#define	STRIPE_INSYNC		4

#define	STRIPE_PREREAD_ACTIVE	5

#define	STRIPE_DELAYED		6

#define	STRIPE_DEGRADED		7

#define	STRIPE_BIT_DELAY	8

#define	STRIPE_EXPANDING	9

#define	STRIPE_EXPAND_SOURCE	10

#define	STRIPE_EXPAND_READY	11

#define	STRIPE_IO_STARTED	12 /* do not count towards 'bypass_count' */

#define	STRIPE_FULL_WRITE	13 /* all blocks are set to be overwritten */

#define	STRIPE_BIOFILL_RUN	14

#define	STRIPE_COMPUTE_RUN	15

/*

 * Operation request flags

 */

#define STRIPE_OP_BIOFILL	0

#define STRIPE_OP_COMPUTE_BLK	1

#define STRIPE_OP_PREXOR	2

#define STRIPE_OP_BIODRAIN	3

#define STRIPE_OP_POSTXOR	4

#define STRIPE_OP_CHECK	5

/*

 * Plugging:

 *

 * To improve write throughput, we need to delay the handling of some

 * stripes until there has been a chance that several write requests

 * for the one stripe have all been collected.

 * In particular, any write request that would require pre-reading

 * is put on a "delayed" queue until there are no stripes currently

 * in a pre-read phase.  Further, if the "delayed" queue is empty when

 * a stripe is put on it then we "plug" the queue and do not process it

 * until an unplug call is made. (the unplug_io_fn() is called).

 *

 * When preread is initiated on a stripe, we set PREREAD_ACTIVE and add

 * it to the count of prereading stripes.

 * When write is initiated, or the stripe refcnt == 0 (just in case) we

 * clear the PREREAD_ACTIVE flag and decrement the count

 * Whenever the 'handle' queue is empty and the device is not plugged, we

 * move any strips from delayed to handle and clear the DELAYED flag and set

 * PREREAD_ACTIVE.

 * In stripe_handle, if we find pre-reading is necessary, we do it if

 * PREREAD_ACTIVE is set, else we set DELAYED which will send it to the delayed queue.

 * HANDLE gets cleared if stripe_handle leave nothing locked.

 */

struct disk_info {

	mdk_rdev_t	*rdev;

};

struct raid5_private_data {

	struct hlist_head	*stripe_hashtbl;

	mddev_t			*mddev;

	struct disk_info	*spare;

	int			chunk_size, level, algorithm;

	int			max_degraded;

	int			raid_disks;

	int			max_nr_stripes;

	/* used during an expand */

	sector_t		expand_progress;	/* MaxSector when no expand happening */

	sector_t		expand_lo; /* from here up to expand_progress it out-of-bounds

					    * as we haven't flushed the metadata yet

					    */

	int			previous_raid_disks;

	struct list_head	handle_list; /* stripes needing handling */

	struct list_head	hold_list; /* preread ready stripes */

	struct list_head	delayed_list; /* stripes that have plugged requests */

	struct list_head	bitmap_list; /* stripes delaying awaiting bitmap update */

	struct bio		*retry_read_aligned; /* currently retrying aligned bios   */

	struct bio		*retry_read_aligned_list; /* aligned bios retry list  */

	atomic_t		preread_active_stripes; /* stripes with scheduled io */

	atomic_t		active_aligned_reads;

	atomic_t		pending_full_writes; /* full write backlog */

	int			bypass_count; /* bypassed prereads */

	int			bypass_threshold; /* preread nice */

	struct list_head	*last_hold; /* detect hold_list promotions */

	atomic_t		reshape_stripes; /* stripes with pending writes for reshape */

	/* unfortunately we need two cache names as we temporarily have

	 * two caches.

	 */

	int			active_name;

	char			cache_name[2][20];

	struct kmem_cache		*slab_cache; /* for allocating stripes */

	int			seq_flush, seq_write;

	int			quiesce;

	int			fullsync;  /* set to 1 if a full sync is needed,

					    * (fresh device added).

					    * Cleared when a sync completes.

					    */

	struct page 		*spare_page; /* Used when checking P/Q in raid6 */

	/*

	 * Free stripes pool

	 */

	atomic_t		active_stripes;

	struct list_head	inactive_list;

	wait_queue_head_t	wait_for_stripe;

	wait_queue_head_t	wait_for_overlap;

	int			inactive_blocked;	/* release of inactive stripes blocked,

							 * waiting for 25% to be free

							 */

	int			pool_size; /* number of disks in stripeheads in pool */

	spinlock_t		device_lock;

	struct disk_info	*disks;

};

typedef struct raid5_private_data raid5_conf_t;

#define mddev_to_conf(mddev) ((raid5_conf_t *) mddev->private)

/*

 * Our supported algorithms

 */

#define ALGORITHM_LEFT_ASYMMETRIC	0

#define ALGORITHM_RIGHT_ASYMMETRIC	1

#define ALGORITHM_LEFT_SYMMETRIC	2

#define ALGORITHM_RIGHT_SYMMETRIC	3

#endif