/*
   * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
   * Written by Alex Tomas <alex@clusterfs.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will 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 Licens
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
   */

  #ifndef _EXT4_EXTENTS
  #define _EXT4_EXTENTS

  #include "ext4.h"

  
  /*

   * With AGGRESSIVE_TEST defined, the capacity of index/leaf blocks

   * becomes very small, so index split, in-depth growing and
   * other hard changes happen much more often.
   * This is for debug purposes only.

   */

  #define AGGRESSIVE_TEST_

  
  /*

   * With EXTENTS_STATS defined, the number of blocks and extents
   * are collected in the truncate path. They'll be shown at
   * umount time.

   */
  #define EXTENTS_STATS__
  
  /*

   * If CHECK_BINSEARCH is defined, then the results of the binary search
   * will also be checked by linear search.

   */
  #define CHECK_BINSEARCH__
  
  /*

   * Turn on EXT_DEBUG to get lots of info about extents operations.

   */
  #define EXT_DEBUG__
  #ifdef EXT_DEBUG
  #define ext_debug(a...)		printk(a)
  #else
  #define ext_debug(a...)
  #endif
  
  /*

   * If EXT_STATS is defined then stats numbers are collected.
   * These number will be displayed at umount time.

   */
  #define EXT_STATS_
  
  
  /*

   * ext4_inode has i_block array (60 bytes total).
   * The first 12 bytes store ext4_extent_header;
   * the remainder stores an array of ext4_extent.

   */
  
  /*

   * This is the extent on-disk structure.
   * It's used at the bottom of the tree.

   */
  struct ext4_extent {
  	__le32	ee_block;	/* first logical block extent covers */
  	__le16	ee_len;		/* number of blocks covered by extent */
  	__le16	ee_start_hi;	/* high 16 bits of physical block */

  	__le32	ee_start_lo;	/* low 32 bits of physical block */

  };
  
  /*

   * This is index on-disk structure.
   * It's used at all the levels except the bottom.

   */
  struct ext4_extent_idx {
  	__le32	ei_block;	/* index covers logical blocks from 'block' */

  	__le32	ei_leaf_lo;	/* pointer to the physical block of the next *

  				 * level. leaf or next index could be there */

  	__le16	ei_leaf_hi;	/* high 16 bits of physical block */
  	__u16	ei_unused;
  };
  
  /*

   * Each block (leaves and indexes), even inode-stored has header.

   */
  struct ext4_extent_header {
  	__le16	eh_magic;	/* probably will support different formats */
  	__le16	eh_entries;	/* number of valid entries */
  	__le16	eh_max;		/* capacity of store in entries */

  	__le16	eh_depth;	/* has tree real underlying blocks? */

  	__le32	eh_generation;	/* generation of the tree */
  };
  
  #define EXT4_EXT_MAGIC		cpu_to_le16(0xf30a)
  
  /*

   * Array of ext4_ext_path contains path to some extent.
   * Creation/lookup routines use it for traversal/splitting/etc.
   * Truncate uses it to simulate recursive walking.

   */
  struct ext4_ext_path {

  	ext4_fsblk_t			p_block;

  	__u16				p_depth;
  	struct ext4_extent		*p_ext;
  	struct ext4_extent_idx		*p_idx;
  	struct ext4_extent_header	*p_hdr;
  	struct buffer_head		*p_bh;
  };
  
  /*
   * structure for external API
   */

  /*
   * to be called by ext4_ext_walk_space()
   * negative retcode - error
   * positive retcode - signal for ext4_ext_walk_space(), see below
   * callback must return valid extent (passed or newly created)
   */

  typedef int (*ext_prepare_callback)(struct inode *, ext4_lblk_t,

  					struct ext4_ext_cache *,
  					struct ext4_extent *, void *);
  
  #define EXT_CONTINUE   0
  #define EXT_BREAK      1
  #define EXT_REPEAT     2

  /*
   * Maximum number of logical blocks in a file; ext4_extent's ee_block is
   * __le32.
   */
  #define EXT_MAX_BLOCKS	0xffffffff

  /*
   * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an
   * initialized extent. This is 2^15 and not (2^16 - 1), since we use the
   * MSB of ee_len field in the extent datastructure to signify if this
   * particular extent is an initialized extent or an uninitialized (i.e.
   * preallocated).
   * EXT_UNINIT_MAX_LEN is the maximum number of blocks we can have in an
   * uninitialized extent.
   * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
   * uninitialized one. In other words, if MSB of ee_len is set, it is an
   * uninitialized extent with only one special scenario when ee_len = 0x8000.
   * In this case we can not have an uninitialized extent of zero length and
   * thus we make it as a special case of initialized extent with 0x8000 length.
   * This way we get better extent-to-group alignment for initialized extents.
   * Hence, the maximum number of blocks we can have in an *initialized*
   * extent is 2^15 (32768) and in an *uninitialized* extent is 2^15-1 (32767).
   */
  #define EXT_INIT_MAX_LEN	(1UL << 15)
  #define EXT_UNINIT_MAX_LEN	(EXT_INIT_MAX_LEN - 1)

  
  #define EXT_FIRST_EXTENT(__hdr__) \
  	((struct ext4_extent *) (((char *) (__hdr__)) +		\
  				 sizeof(struct ext4_extent_header)))
  #define EXT_FIRST_INDEX(__hdr__) \
  	((struct ext4_extent_idx *) (((char *) (__hdr__)) +	\
  				     sizeof(struct ext4_extent_header)))
  #define EXT_HAS_FREE_INDEX(__path__) \

  	(le16_to_cpu((__path__)->p_hdr->eh_entries) \
  				     < le16_to_cpu((__path__)->p_hdr->eh_max))

  #define EXT_LAST_EXTENT(__hdr__) \
  	(EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
  #define EXT_LAST_INDEX(__hdr__) \
  	(EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
  #define EXT_MAX_EXTENT(__hdr__) \
  	(EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
  #define EXT_MAX_INDEX(__hdr__) \
  	(EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)
  
  static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
  {
  	return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
  }
  
  static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh)
  {
  	return (struct ext4_extent_header *) bh->b_data;
  }
  
  static inline unsigned short ext_depth(struct inode *inode)
  {
  	return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
  }

  static inline void
  ext4_ext_invalidate_cache(struct inode *inode)
  {

  	EXT4_I(inode)->i_cached_extent.ec_len = 0;

  }

  static inline void ext4_ext_mark_uninitialized(struct ext4_extent *ext)
  {

  	/* We can not have an uninitialized extent of zero length! */
  	BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
  	ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);

  }
  
  static inline int ext4_ext_is_uninitialized(struct ext4_extent *ext)
  {

  	/* Extent with ee_len of 0x8000 is treated as an initialized extent */
  	return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);

  }
  
  static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
  {

  	return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
  		le16_to_cpu(ext->ee_len) :
  		(le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));

  }

  static inline void ext4_ext_mark_initialized(struct ext4_extent *ext)
  {
  	ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext));
  }

  /*
   * ext4_ext_pblock:
   * combine low and high parts of physical block number into ext4_fsblk_t
   */
  static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex)
  {
  	ext4_fsblk_t block;
  
  	block = le32_to_cpu(ex->ee_start_lo);
  	block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
  	return block;
  }
  
  /*
   * ext4_idx_pblock:
   * combine low and high parts of a leaf physical block number into ext4_fsblk_t
   */
  static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix)
  {
  	ext4_fsblk_t block;
  
  	block = le32_to_cpu(ix->ei_leaf_lo);
  	block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
  	return block;
  }
  
  /*
   * ext4_ext_store_pblock:
   * stores a large physical block number into an extent struct,
   * breaking it into parts
   */
  static inline void ext4_ext_store_pblock(struct ext4_extent *ex,
  					 ext4_fsblk_t pb)
  {
  	ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
  	ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
  				      0xffff);
  }
  
  /*
   * ext4_idx_store_pblock:
   * stores a large physical block number into an index struct,
   * breaking it into parts
   */
  static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix,
  					 ext4_fsblk_t pb)
  {
  	ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
  	ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
  				     0xffff);
  }

  extern int ext4_ext_calc_metadata_amount(struct inode *inode,

  					 ext4_lblk_t lblocks);

  extern int ext4_extent_tree_init(handle_t *, struct inode *);

  extern int ext4_ext_calc_credits_for_single_extent(struct inode *inode,
  						   int num,
  						   struct ext4_ext_path *path);

  extern int ext4_can_extents_be_merged(struct inode *inode,
  				      struct ext4_extent *ex1,
  				      struct ext4_extent *ex2);

  extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *, int);

  extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t,
  							struct ext4_ext_path *);

  extern void ext4_ext_drop_refs(struct ext4_ext_path *);

  extern int ext4_ext_check_inode(struct inode *inode);

  extern int ext4_find_delalloc_cluster(struct inode *inode, ext4_lblk_t lblk,
  				      int search_hint_reverse);

  #endif /* _EXT4_EXTENTS */