/*
   * Copyright (c) 2000-2005 Silicon Graphics, Inc.
   * All Rights Reserved.
   *
   * 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.
   *
   * This program is distributed in the hope that it would be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write the Free Software Foundation,
   * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   */
  #ifndef __XFS_BUF_H__
  #define __XFS_BUF_H__
  
  #include <linux/list.h>
  #include <linux/types.h>
  #include <linux/spinlock.h>
  #include <linux/mm.h>
  #include <linux/fs.h>
  #include <linux/buffer_head.h>
  #include <linux/uio.h>
  #include <linux/list_lru.h>
  
  /*
   *	Base types
   */
  
  #define XFS_BUF_DADDR_NULL	((xfs_daddr_t) (-1LL))
  
  typedef enum {
  	XBRW_READ = 1,			/* transfer into target memory */
  	XBRW_WRITE = 2,			/* transfer from target memory */
  	XBRW_ZERO = 3,			/* Zero target memory */
  } xfs_buf_rw_t;
  
  #define XBF_READ	 (1 << 0) /* buffer intended for reading from device */
  #define XBF_WRITE	 (1 << 1) /* buffer intended for writing to device */
  #define XBF_READ_AHEAD	 (1 << 2) /* asynchronous read-ahead */
  #define XBF_ASYNC	 (1 << 4) /* initiator will not wait for completion */
  #define XBF_DONE	 (1 << 5) /* all pages in the buffer uptodate */
  #define XBF_STALE	 (1 << 6) /* buffer has been staled, do not find it */
  #define XBF_WRITE_FAIL	 (1 << 24)/* async writes have failed on this buffer */
  
  /* I/O hints for the BIO layer */
  #define XBF_SYNCIO	 (1 << 10)/* treat this buffer as synchronous I/O */
  #define XBF_FUA		 (1 << 11)/* force cache write through mode */
  #define XBF_FLUSH	 (1 << 12)/* flush the disk cache before a write */
  
  /* flags used only as arguments to access routines */
  #define XBF_TRYLOCK	 (1 << 16)/* lock requested, but do not wait */
  #define XBF_UNMAPPED	 (1 << 17)/* do not map the buffer */
  
  /* flags used only internally */
  #define _XBF_PAGES	 (1 << 20)/* backed by refcounted pages */
  #define _XBF_KMEM	 (1 << 21)/* backed by heap memory */
  #define _XBF_DELWRI_Q	 (1 << 22)/* buffer on a delwri queue */
  #define _XBF_COMPOUND	 (1 << 23)/* compound buffer */
  
  typedef unsigned int xfs_buf_flags_t;
  
  #define XFS_BUF_FLAGS \
  	{ XBF_READ,		"READ" }, \
  	{ XBF_WRITE,		"WRITE" }, \
  	{ XBF_READ_AHEAD,	"READ_AHEAD" }, \
  	{ XBF_ASYNC,		"ASYNC" }, \
  	{ XBF_DONE,		"DONE" }, \
  	{ XBF_STALE,		"STALE" }, \
  	{ XBF_WRITE_FAIL,	"WRITE_FAIL" }, \
  	{ XBF_SYNCIO,		"SYNCIO" }, \
  	{ XBF_FUA,		"FUA" }, \
  	{ XBF_FLUSH,		"FLUSH" }, \
  	{ XBF_TRYLOCK,		"TRYLOCK" },	/* should never be set */\
  	{ XBF_UNMAPPED,		"UNMAPPED" },	/* ditto */\
  	{ _XBF_PAGES,		"PAGES" }, \
  	{ _XBF_KMEM,		"KMEM" }, \
  	{ _XBF_DELWRI_Q,	"DELWRI_Q" }, \
  	{ _XBF_COMPOUND,	"COMPOUND" }
  
  
  /*
   * Internal state flags.
   */
  #define XFS_BSTATE_DISPOSE	 (1 << 0)	/* buffer being discarded */
  
  /*
   * The xfs_buftarg contains 2 notions of "sector size" -
   *
   * 1) The metadata sector size, which is the minimum unit and
   *    alignment of IO which will be performed by metadata operations.
   * 2) The device logical sector size
   *
   * The first is specified at mkfs time, and is stored on-disk in the
   * superblock's sb_sectsize.
   *
   * The latter is derived from the underlying device, and controls direct IO
   * alignment constraints.
   */
  typedef struct xfs_buftarg {
  	dev_t			bt_dev;
  	struct block_device	*bt_bdev;
  	struct backing_dev_info	*bt_bdi;
  	struct xfs_mount	*bt_mount;
  	unsigned int		bt_meta_sectorsize;
  	size_t			bt_meta_sectormask;
  	size_t			bt_logical_sectorsize;
  	size_t			bt_logical_sectormask;
  
  	/* LRU control structures */
  	struct shrinker		bt_shrinker;
  	struct list_lru		bt_lru;
  } xfs_buftarg_t;
  
  struct xfs_buf;
  typedef void (*xfs_buf_iodone_t)(struct xfs_buf *);
  
  
  #define XB_PAGES	2
  
  struct xfs_buf_map {
  	xfs_daddr_t		bm_bn;	/* block number for I/O */
  	int			bm_len;	/* size of I/O */
  };
  
  #define DEFINE_SINGLE_BUF_MAP(map, blkno, numblk) \
  	struct xfs_buf_map (map) = { .bm_bn = (blkno), .bm_len = (numblk) };
  
  struct xfs_buf_ops {
  	void (*verify_read)(struct xfs_buf *);
  	void (*verify_write)(struct xfs_buf *);
  };
  
  typedef struct xfs_buf {
  	/*
  	 * first cacheline holds all the fields needed for an uncontended cache
  	 * hit to be fully processed. The semaphore straddles the cacheline
  	 * boundary, but the counter and lock sits on the first cacheline,
  	 * which is the only bit that is touched if we hit the semaphore
  	 * fast-path on locking.
  	 */
  	struct rb_node		b_rbnode;	/* rbtree node */
  	xfs_daddr_t		b_bn;		/* block number of buffer */
  	int			b_length;	/* size of buffer in BBs */
  	atomic_t		b_hold;		/* reference count */
  	atomic_t		b_lru_ref;	/* lru reclaim ref count */
  	xfs_buf_flags_t		b_flags;	/* status flags */
  	struct semaphore	b_sema;		/* semaphore for lockables */
  
  	/*
  	 * concurrent access to b_lru and b_lru_flags are protected by
  	 * bt_lru_lock and not by b_sema
  	 */
  	struct list_head	b_lru;		/* lru list */
  	spinlock_t		b_lock;		/* internal state lock */
  	unsigned int		b_state;	/* internal state flags */
  	wait_queue_head_t	b_waiters;	/* unpin waiters */
  	struct list_head	b_list;
  	struct xfs_perag	*b_pag;		/* contains rbtree root */
  	xfs_buftarg_t		*b_target;	/* buffer target (device) */
  	void			*b_addr;	/* virtual address of buffer */
  	struct work_struct	b_iodone_work;
  	xfs_buf_iodone_t	b_iodone;	/* I/O completion function */
  	struct completion	b_iowait;	/* queue for I/O waiters */
  	void			*b_fspriv;
  	struct xfs_trans	*b_transp;
  	struct page		**b_pages;	/* array of page pointers */
  	struct page		*b_page_array[XB_PAGES]; /* inline pages */
  	struct xfs_buf_map	*b_maps;	/* compound buffer map */
  	struct xfs_buf_map	__b_map;	/* inline compound buffer map */
  	int			b_map_count;
  	int			b_io_length;	/* IO size in BBs */
  	atomic_t		b_pin_count;	/* pin count */
  	atomic_t		b_io_remaining;	/* #outstanding I/O requests */
  	unsigned int		b_page_count;	/* size of page array */
  	unsigned int		b_offset;	/* page offset in first page */
  	unsigned short		b_error;	/* error code on I/O */
  	const struct xfs_buf_ops	*b_ops;
  
  #ifdef XFS_BUF_LOCK_TRACKING
  	int			b_last_holder;
  #endif
  } xfs_buf_t;
  
  /* Finding and Reading Buffers */
  struct xfs_buf *_xfs_buf_find(struct xfs_buftarg *target,
  			      struct xfs_buf_map *map, int nmaps,
  			      xfs_buf_flags_t flags, struct xfs_buf *new_bp);
  
  static inline struct xfs_buf *
  xfs_incore(
  	struct xfs_buftarg	*target,
  	xfs_daddr_t		blkno,
  	size_t			numblks,
  	xfs_buf_flags_t		flags)
  {
  	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
  	return _xfs_buf_find(target, &map, 1, flags, NULL);
  }
  
  struct xfs_buf *_xfs_buf_alloc(struct xfs_buftarg *target,
  			       struct xfs_buf_map *map, int nmaps,
  			       xfs_buf_flags_t flags);
  
  static inline struct xfs_buf *
  xfs_buf_alloc(
  	struct xfs_buftarg	*target,
  	xfs_daddr_t		blkno,
  	size_t			numblks,
  	xfs_buf_flags_t		flags)
  {
  	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
  	return _xfs_buf_alloc(target, &map, 1, flags);
  }
  
  struct xfs_buf *xfs_buf_get_map(struct xfs_buftarg *target,
  			       struct xfs_buf_map *map, int nmaps,
  			       xfs_buf_flags_t flags);
  struct xfs_buf *xfs_buf_read_map(struct xfs_buftarg *target,
  			       struct xfs_buf_map *map, int nmaps,
  			       xfs_buf_flags_t flags,
  			       const struct xfs_buf_ops *ops);
  void xfs_buf_readahead_map(struct xfs_buftarg *target,
  			       struct xfs_buf_map *map, int nmaps,
  			       const struct xfs_buf_ops *ops);
  
  static inline struct xfs_buf *
  xfs_buf_get(
  	struct xfs_buftarg	*target,
  	xfs_daddr_t		blkno,
  	size_t			numblks,
  	xfs_buf_flags_t		flags)
  {
  	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
  	return xfs_buf_get_map(target, &map, 1, flags);
  }
  
  static inline struct xfs_buf *
  xfs_buf_read(
  	struct xfs_buftarg	*target,
  	xfs_daddr_t		blkno,
  	size_t			numblks,
  	xfs_buf_flags_t		flags,
  	const struct xfs_buf_ops *ops)
  {
  	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
  	return xfs_buf_read_map(target, &map, 1, flags, ops);
  }
  
  static inline void
  xfs_buf_readahead(
  	struct xfs_buftarg	*target,
  	xfs_daddr_t		blkno,
  	size_t			numblks,
  	const struct xfs_buf_ops *ops)
  {
  	DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
  	return xfs_buf_readahead_map(target, &map, 1, ops);
  }
  
  struct xfs_buf *xfs_buf_get_empty(struct xfs_buftarg *target, size_t numblks);
  void xfs_buf_set_empty(struct xfs_buf *bp, size_t numblks);
  int xfs_buf_associate_memory(struct xfs_buf *bp, void *mem, size_t length);
  
  struct xfs_buf *xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks,
  				int flags);
  struct xfs_buf *xfs_buf_read_uncached(struct xfs_buftarg *target,
  				xfs_daddr_t daddr, size_t numblks, int flags,
  				const struct xfs_buf_ops *ops);
  void xfs_buf_hold(struct xfs_buf *bp);
  
  /* Releasing Buffers */
  extern void xfs_buf_free(xfs_buf_t *);
  extern void xfs_buf_rele(xfs_buf_t *);
  
  /* Locking and Unlocking Buffers */
  extern int xfs_buf_trylock(xfs_buf_t *);
  extern void xfs_buf_lock(xfs_buf_t *);
  extern void xfs_buf_unlock(xfs_buf_t *);
  #define xfs_buf_islocked(bp) \
  	((bp)->b_sema.count <= 0)
  
  /* Buffer Read and Write Routines */
  extern int xfs_bwrite(struct xfs_buf *bp);
  extern void xfs_buf_ioend(xfs_buf_t *,	int);
  extern void xfs_buf_ioerror(xfs_buf_t *, int);
  extern void xfs_buf_ioerror_alert(struct xfs_buf *, const char *func);
  extern void xfs_buf_iorequest(xfs_buf_t *);
  extern int xfs_buf_iowait(xfs_buf_t *);
  extern void xfs_buf_iomove(xfs_buf_t *, size_t, size_t, void *,
  				xfs_buf_rw_t);
  #define xfs_buf_zero(bp, off, len) \
  	    xfs_buf_iomove((bp), (off), (len), NULL, XBRW_ZERO)
  
  extern int xfs_bioerror_relse(struct xfs_buf *);
  
  static inline int xfs_buf_geterror(xfs_buf_t *bp)
  {
  	return bp ? bp->b_error : ENOMEM;
  }
  
  /* Buffer Utility Routines */
  extern xfs_caddr_t xfs_buf_offset(xfs_buf_t *, size_t);
  
  /* Delayed Write Buffer Routines */
  extern bool xfs_buf_delwri_queue(struct xfs_buf *, struct list_head *);
  extern int xfs_buf_delwri_submit(struct list_head *);
  extern int xfs_buf_delwri_submit_nowait(struct list_head *);
  
  /* Buffer Daemon Setup Routines */
  extern int xfs_buf_init(void);
  extern void xfs_buf_terminate(void);
  
  #define XFS_BUF_ZEROFLAGS(bp) \
  	((bp)->b_flags &= ~(XBF_READ|XBF_WRITE|XBF_ASYNC| \
  			    XBF_SYNCIO|XBF_FUA|XBF_FLUSH| \
  			    XBF_WRITE_FAIL))
  
  void xfs_buf_stale(struct xfs_buf *bp);
  #define XFS_BUF_UNSTALE(bp)	((bp)->b_flags &= ~XBF_STALE)
  #define XFS_BUF_ISSTALE(bp)	((bp)->b_flags & XBF_STALE)
  
  #define XFS_BUF_DONE(bp)	((bp)->b_flags |= XBF_DONE)
  #define XFS_BUF_UNDONE(bp)	((bp)->b_flags &= ~XBF_DONE)
  #define XFS_BUF_ISDONE(bp)	((bp)->b_flags & XBF_DONE)
  
  #define XFS_BUF_ASYNC(bp)	((bp)->b_flags |= XBF_ASYNC)
  #define XFS_BUF_UNASYNC(bp)	((bp)->b_flags &= ~XBF_ASYNC)
  #define XFS_BUF_ISASYNC(bp)	((bp)->b_flags & XBF_ASYNC)
  
  #define XFS_BUF_READ(bp)	((bp)->b_flags |= XBF_READ)
  #define XFS_BUF_UNREAD(bp)	((bp)->b_flags &= ~XBF_READ)
  #define XFS_BUF_ISREAD(bp)	((bp)->b_flags & XBF_READ)
  
  #define XFS_BUF_WRITE(bp)	((bp)->b_flags |= XBF_WRITE)
  #define XFS_BUF_UNWRITE(bp)	((bp)->b_flags &= ~XBF_WRITE)
  #define XFS_BUF_ISWRITE(bp)	((bp)->b_flags & XBF_WRITE)
  
  /*
   * These macros use the IO block map rather than b_bn. b_bn is now really
   * just for the buffer cache index for cached buffers. As IO does not use b_bn
   * anymore, uncached buffers do not use b_bn at all and hence must modify the IO
   * map directly. Uncached buffers are not allowed to be discontiguous, so this
   * is safe to do.
   *
   * In future, uncached buffers will pass the block number directly to the io
   * request function and hence these macros will go away at that point.
   */
  #define XFS_BUF_ADDR(bp)		((bp)->b_maps[0].bm_bn)
  #define XFS_BUF_SET_ADDR(bp, bno)	((bp)->b_maps[0].bm_bn = (xfs_daddr_t)(bno))
  
  static inline void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
  {
  	atomic_set(&bp->b_lru_ref, lru_ref);
  }
  
  static inline int xfs_buf_ispinned(struct xfs_buf *bp)
  {
  	return atomic_read(&bp->b_pin_count);
  }
  
  static inline void xfs_buf_relse(xfs_buf_t *bp)
  {
  	xfs_buf_unlock(bp);
  	xfs_buf_rele(bp);
  }
  
  /*
   *	Handling of buftargs.
   */
  extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
  			struct block_device *, int, const char *);
  extern void xfs_free_buftarg(struct xfs_mount *, struct xfs_buftarg *);
  extern void xfs_wait_buftarg(xfs_buftarg_t *);
  extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int, unsigned int);
  
  #define xfs_getsize_buftarg(buftarg)	block_size((buftarg)->bt_bdev)
  #define xfs_readonly_buftarg(buftarg)	bdev_read_only((buftarg)->bt_bdev)
  
  #endif	/* __XFS_BUF_H__ */