/*
   * segbuf.h - NILFS Segment buffer prototypes 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_SEGBUF_H
  #define _NILFS_SEGBUF_H
  
  #include <linux/fs.h>
  #include <linux/buffer_head.h>
  #include <linux/bio.h>
  #include <linux/completion.h>

  
  /**
   * struct nilfs_segsum_info - On-memory segment summary
   * @flags: Flags
   * @nfinfo: Number of file information structures
   * @nblocks: Number of blocks included in the partial segment
   * @nsumblk: Number of summary blocks
   * @sumbytes: Byte count of segment summary
   * @nfileblk: Total number of file blocks
   * @seg_seq: Segment sequence number

   * @cno: Checkpoint number

   * @ctime: Creation time
   * @next: Block number of the next full segment
   */
  struct nilfs_segsum_info {
  	unsigned int		flags;
  	unsigned long		nfinfo;
  	unsigned long		nblocks;
  	unsigned long		nsumblk;
  	unsigned long		sumbytes;
  	unsigned long		nfileblk;
  	u64			seg_seq;

  	__u64			cno;

  	time_t			ctime;
  	sector_t		next;
  };

  /**
   * struct nilfs_segment_buffer - Segment buffer
   * @sb_super: back pointer to a superblock struct
   * @sb_list: List head to chain this structure

   * @sb_sum: On-memory segment summary
   * @sb_segnum: Index number of the full segment
   * @sb_nextnum: Index number of the next full segment
   * @sb_fseg_start: Start block number of the full segment
   * @sb_fseg_end: End block number of the full segment
   * @sb_pseg_start: Disk block number of partial segment
   * @sb_rest_blocks: Number of residual blocks in the current segment
   * @sb_segsum_buffers: List of buffers for segment summaries
   * @sb_payload_buffers: List of buffers for segment payload

   * @sb_super_root: Pointer to buffer storing a super root block (if exists)

   * @sb_nbio: Number of flying bio requests
   * @sb_err: I/O error status
   * @sb_bio_event: Completion event of log writing

   */
  struct nilfs_segment_buffer {
  	struct super_block     *sb_super;
  	struct list_head	sb_list;

  
  	/* Segment information */
  	struct nilfs_segsum_info sb_sum;
  	__u64			sb_segnum;
  	__u64			sb_nextnum;
  	sector_t		sb_fseg_start, sb_fseg_end;
  	sector_t		sb_pseg_start;

  	unsigned int		sb_rest_blocks;

  
  	/* Buffers */
  	struct list_head	sb_segsum_buffers;
  	struct list_head	sb_payload_buffers; /* including super root */

  	struct buffer_head     *sb_super_root;

  
  	/* io status */

  	int			sb_nbio;
  	atomic_t		sb_err;
  	struct completion	sb_bio_event;

  };
  
  #define NILFS_LIST_SEGBUF(head)  \
  	list_entry((head), struct nilfs_segment_buffer, sb_list)
  #define NILFS_NEXT_SEGBUF(segbuf)  NILFS_LIST_SEGBUF((segbuf)->sb_list.next)
  #define NILFS_PREV_SEGBUF(segbuf)  NILFS_LIST_SEGBUF((segbuf)->sb_list.prev)
  #define NILFS_LAST_SEGBUF(head)    NILFS_LIST_SEGBUF((head)->prev)
  #define NILFS_FIRST_SEGBUF(head)   NILFS_LIST_SEGBUF((head)->next)
  #define NILFS_SEGBUF_IS_LAST(segbuf, head)  ((segbuf)->sb_list.next == (head))
  
  #define nilfs_for_each_segbuf_before(s, t, h) \
  	for ((s) = NILFS_FIRST_SEGBUF(h); (s) != (t); \
  	     (s) = NILFS_NEXT_SEGBUF(s))
  
  #define NILFS_SEGBUF_FIRST_BH(head)  \
  	(list_entry((head)->next, struct buffer_head, b_assoc_buffers))
  #define NILFS_SEGBUF_NEXT_BH(bh)  \
  	(list_entry((bh)->b_assoc_buffers.next, struct buffer_head, \
  		    b_assoc_buffers))
  #define NILFS_SEGBUF_BH_IS_LAST(bh, head)  ((bh)->b_assoc_buffers.next == head)

  extern struct kmem_cache *nilfs_segbuf_cachep;

  struct nilfs_segment_buffer *nilfs_segbuf_new(struct super_block *);
  void nilfs_segbuf_free(struct nilfs_segment_buffer *);

  void nilfs_segbuf_map(struct nilfs_segment_buffer *, __u64, unsigned long,
  		      struct the_nilfs *);

  void nilfs_segbuf_map_cont(struct nilfs_segment_buffer *segbuf,
  			   struct nilfs_segment_buffer *prev);

  void nilfs_segbuf_set_next_segnum(struct nilfs_segment_buffer *, __u64,
  				  struct the_nilfs *);

  int nilfs_segbuf_reset(struct nilfs_segment_buffer *, unsigned int, time_t,
  		       __u64);

  int nilfs_segbuf_extend_segsum(struct nilfs_segment_buffer *);
  int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *,
  				struct buffer_head **);
  void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *);

  static inline int nilfs_segbuf_simplex(struct nilfs_segment_buffer *segbuf)
  {
  	unsigned int flags = segbuf->sb_sum.flags;
  
  	return (flags & (NILFS_SS_LOGBGN | NILFS_SS_LOGEND)) ==
  		(NILFS_SS_LOGBGN | NILFS_SS_LOGEND);
  }
  
  static inline int nilfs_segbuf_empty(struct nilfs_segment_buffer *segbuf)
  {
  	return segbuf->sb_sum.nblocks == segbuf->sb_sum.nsumblk;
  }

  static inline void
  nilfs_segbuf_add_segsum_buffer(struct nilfs_segment_buffer *segbuf,
  			       struct buffer_head *bh)
  {
  	list_add_tail(&bh->b_assoc_buffers, &segbuf->sb_segsum_buffers);
  	segbuf->sb_sum.nblocks++;
  	segbuf->sb_sum.nsumblk++;
  }
  
  static inline void
  nilfs_segbuf_add_payload_buffer(struct nilfs_segment_buffer *segbuf,
  				struct buffer_head *bh)
  {
  	list_add_tail(&bh->b_assoc_buffers, &segbuf->sb_payload_buffers);
  	segbuf->sb_sum.nblocks++;
  }
  
  static inline void
  nilfs_segbuf_add_file_buffer(struct nilfs_segment_buffer *segbuf,
  			     struct buffer_head *bh)
  {
  	get_bh(bh);
  	nilfs_segbuf_add_payload_buffer(segbuf, bh);
  	segbuf->sb_sum.nfileblk++;
  }

  void nilfs_clear_logs(struct list_head *logs);
  void nilfs_truncate_logs(struct list_head *logs,
  			 struct nilfs_segment_buffer *last);

  int nilfs_write_logs(struct list_head *logs, struct the_nilfs *nilfs);

  int nilfs_wait_on_logs(struct list_head *logs);

  void nilfs_add_checksums_on_logs(struct list_head *logs, u32 seed);

  
  static inline void nilfs_destroy_logs(struct list_head *logs)
  {
  	nilfs_truncate_logs(logs, NULL);
  }

  #endif /* _NILFS_SEGBUF_H */