/*
   * mdt.h - NILFS meta data file prototype and definitions
   *
   * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
   *
   * 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 of the License, or
   * (at your option) any later version.
   *
   * 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.
   *
   * Written by Ryusuke Konishi.
   */
  
  #ifndef _NILFS_MDT_H
  #define _NILFS_MDT_H
  
  #include <linux/buffer_head.h>
  #include <linux/blockgroup_lock.h>
  #include "nilfs.h"
  #include "page.h"
  
  /**
   * struct nilfs_shadow_map - shadow mapping of meta data file
   * @bmap_store: shadow copy of bmap state
   * @frozen_data: shadowed dirty data pages
   * @frozen_btnodes: shadowed dirty b-tree nodes' pages
   * @frozen_buffers: list of frozen buffers
   */
  struct nilfs_shadow_map {
  	struct nilfs_bmap_store bmap_store;
  	struct address_space frozen_data;
  	struct address_space frozen_btnodes;
  	struct list_head frozen_buffers;
  };
  
  /**
   * struct nilfs_mdt_info - on-memory private data of meta data files
   * @mi_sem: reader/writer semaphore for meta data operations
   * @mi_bgl: per-blockgroup locking
   * @mi_entry_size: size of an entry
   * @mi_first_entry_offset: offset to the first entry
   * @mi_entries_per_block: number of entries in a block
   * @mi_palloc_cache: persistent object allocator cache
   * @mi_shadow: shadow of bmap and page caches
   * @mi_blocks_per_group: number of blocks in a group
   * @mi_blocks_per_desc_block: number of blocks per descriptor block
   */
  struct nilfs_mdt_info {
  	struct rw_semaphore	mi_sem;
  	struct blockgroup_lock *mi_bgl;
  	unsigned int		mi_entry_size;
  	unsigned int		mi_first_entry_offset;
  	unsigned long		mi_entries_per_block;
  	struct nilfs_palloc_cache *mi_palloc_cache;
  	struct nilfs_shadow_map *mi_shadow;
  	unsigned long		mi_blocks_per_group;
  	unsigned long		mi_blocks_per_desc_block;
  };
  
  static inline struct nilfs_mdt_info *NILFS_MDT(const struct inode *inode)
  {
  	return inode->i_private;
  }
  
  static inline int nilfs_is_metadata_file_inode(const struct inode *inode)
  {
  	return inode->i_private != NULL;
  }
  
  /* Default GFP flags using highmem */
  #define NILFS_MDT_GFP      (__GFP_RECLAIM | __GFP_IO | __GFP_HIGHMEM)
  
  int nilfs_mdt_get_block(struct inode *, unsigned long, int,
  			void (*init_block)(struct inode *,
  					   struct buffer_head *, void *),
  			struct buffer_head **);
  int nilfs_mdt_find_block(struct inode *inode, unsigned long start,
  			 unsigned long end, unsigned long *blkoff,
  			 struct buffer_head **out_bh);
  int nilfs_mdt_delete_block(struct inode *, unsigned long);
  int nilfs_mdt_forget_block(struct inode *, unsigned long);
  int nilfs_mdt_fetch_dirty(struct inode *);
  
  int nilfs_mdt_init(struct inode *inode, gfp_t gfp_mask, size_t objsz);
  void nilfs_mdt_clear(struct inode *inode);
  void nilfs_mdt_destroy(struct inode *inode);
  
  void nilfs_mdt_set_entry_size(struct inode *, unsigned int, unsigned int);
  
  int nilfs_mdt_setup_shadow_map(struct inode *inode,
  			       struct nilfs_shadow_map *shadow);
  int nilfs_mdt_save_to_shadow_map(struct inode *inode);
  void nilfs_mdt_restore_from_shadow_map(struct inode *inode);
  void nilfs_mdt_clear_shadow_map(struct inode *inode);
  int nilfs_mdt_freeze_buffer(struct inode *inode, struct buffer_head *bh);
  struct buffer_head *nilfs_mdt_get_frozen_buffer(struct inode *inode,
  						struct buffer_head *bh);
  
  static inline void nilfs_mdt_mark_dirty(struct inode *inode)
  {
  	if (!test_bit(NILFS_I_DIRTY, &NILFS_I(inode)->i_state))
  		set_bit(NILFS_I_DIRTY, &NILFS_I(inode)->i_state);
  }
  
  static inline void nilfs_mdt_clear_dirty(struct inode *inode)
  {
  	clear_bit(NILFS_I_DIRTY, &NILFS_I(inode)->i_state);
  }
  
  static inline __u64 nilfs_mdt_cno(struct inode *inode)
  {
  	return ((struct the_nilfs *)inode->i_sb->s_fs_info)->ns_cno;
  }
  
  static inline spinlock_t *
  nilfs_mdt_bgl_lock(struct inode *inode, unsigned int block_group)
  {
  	return bgl_lock_ptr(NILFS_MDT(inode)->mi_bgl, block_group);
  }
  
  #endif /* _NILFS_MDT_H */