/*
   * the_nilfs.h - the_nilfs shared structure.
   *
   * 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.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   *
   * Written by Ryusuke Konishi <ryusuke@osrg.net>
   *
   */
  
  #ifndef _THE_NILFS_H
  #define _THE_NILFS_H
  
  #include <linux/types.h>
  #include <linux/buffer_head.h>
  #include <linux/rbtree.h>
  #include <linux/fs.h>
  #include <linux/blkdev.h>
  #include <linux/backing-dev.h>
  #include <linux/slab.h>
  
  struct nilfs_sc_info;
  
  /* the_nilfs struct */
  enum {
  	THE_NILFS_INIT = 0,     /* Information from super_block is set */
  	THE_NILFS_DISCONTINUED,	/* 'next' pointer chain has broken */
  	THE_NILFS_GC_RUNNING,	/* gc process is running */
  	THE_NILFS_SB_DIRTY,	/* super block is dirty */
  };
  
  /**
   * struct the_nilfs - struct to supervise multiple nilfs mount points
   * @ns_flags: flags
   * @ns_bdev: block device
   * @ns_sem: semaphore for shared states
   * @ns_snapshot_mount_mutex: mutex to protect snapshot mounts
   * @ns_sbh: buffer heads of on-disk super blocks
   * @ns_sbp: pointers to super block data
   * @ns_sbwtime: previous write time of super block
   * @ns_sbwcount: write count of super block
   * @ns_sbsize: size of valid data in super block
   * @ns_mount_state: file system state
   * @ns_seg_seq: segment sequence counter
   * @ns_segnum: index number of the latest full segment.
   * @ns_nextnum: index number of the full segment index to be used next
   * @ns_pseg_offset: offset of next partial segment in the current full segment
   * @ns_cno: next checkpoint number
   * @ns_ctime: write time of the last segment
   * @ns_nongc_ctime: write time of the last segment not for cleaner operation
   * @ns_ndirtyblks: Number of dirty data blocks
   * @ns_last_segment_lock: lock protecting fields for the latest segment
   * @ns_last_pseg: start block number of the latest segment
   * @ns_last_seq: sequence value of the latest segment
   * @ns_last_cno: checkpoint number of the latest segment
   * @ns_prot_seq: least sequence number of segments which must not be reclaimed
   * @ns_prev_seq: base sequence number used to decide if advance log cursor
   * @ns_writer: log writer
   * @ns_segctor_sem: semaphore protecting log write
   * @ns_dat: DAT file inode
   * @ns_cpfile: checkpoint file inode
   * @ns_sufile: segusage file inode
   * @ns_cptree: rb-tree of all mounted checkpoints (nilfs_root)
   * @ns_cptree_lock: lock protecting @ns_cptree
   * @ns_dirty_files: list of dirty files
   * @ns_inode_lock: lock protecting @ns_dirty_files
   * @ns_gc_inodes: dummy inodes to keep live blocks
   * @ns_next_generation: next generation number for inodes
   * @ns_next_gen_lock: lock protecting @ns_next_generation
   * @ns_mount_opt: mount options
   * @ns_resuid: uid for reserved blocks
   * @ns_resgid: gid for reserved blocks
   * @ns_interval: checkpoint creation interval
   * @ns_watermark: watermark for the number of dirty buffers
   * @ns_blocksize_bits: bit length of block size
   * @ns_blocksize: block size
   * @ns_nsegments: number of segments in filesystem
   * @ns_blocks_per_segment: number of blocks per segment
   * @ns_r_segments_percentage: reserved segments percentage
   * @ns_nrsvsegs: number of reserved segments
   * @ns_first_data_block: block number of first data block
   * @ns_inode_size: size of on-disk inode
   * @ns_first_ino: first not-special inode number
   * @ns_crc_seed: seed value of CRC32 calculation
   */
  struct the_nilfs {
  	unsigned long		ns_flags;
  
  	struct block_device    *ns_bdev;
  	struct rw_semaphore	ns_sem;
  	struct mutex		ns_snapshot_mount_mutex;
  
  	/*
  	 * used for
  	 * - loading the latest checkpoint exclusively.
  	 * - allocating a new full segment.
  	 */
  	struct buffer_head     *ns_sbh[2];
  	struct nilfs_super_block *ns_sbp[2];
  	time_t			ns_sbwtime;
  	unsigned		ns_sbwcount;
  	unsigned		ns_sbsize;
  	unsigned		ns_mount_state;
  
  	/*
  	 * Following fields are dedicated to a writable FS-instance.
  	 * Except for the period seeking checkpoint, code outside the segment
  	 * constructor must lock a segment semaphore while accessing these
  	 * fields.
  	 * The writable FS-instance is sole during a lifetime of the_nilfs.
  	 */
  	u64			ns_seg_seq;
  	__u64			ns_segnum;
  	__u64			ns_nextnum;
  	unsigned long		ns_pseg_offset;
  	__u64			ns_cno;
  	time_t			ns_ctime;
  	time_t			ns_nongc_ctime;
  	atomic_t		ns_ndirtyblks;
  
  	/*
  	 * The following fields hold information on the latest partial segment
  	 * written to disk with a super root.  These fields are protected by
  	 * ns_last_segment_lock.
  	 */
  	spinlock_t		ns_last_segment_lock;
  	sector_t		ns_last_pseg;
  	u64			ns_last_seq;
  	__u64			ns_last_cno;
  	u64			ns_prot_seq;
  	u64			ns_prev_seq;
  
  	struct nilfs_sc_info   *ns_writer;
  	struct rw_semaphore	ns_segctor_sem;
  
  	/*
  	 * Following fields are lock free except for the period before
  	 * the_nilfs is initialized.
  	 */
  	struct inode	       *ns_dat;
  	struct inode	       *ns_cpfile;
  	struct inode	       *ns_sufile;
  
  	/* Checkpoint tree */
  	struct rb_root		ns_cptree;
  	spinlock_t		ns_cptree_lock;
  
  	/* Dirty inode list */
  	struct list_head	ns_dirty_files;
  	spinlock_t		ns_inode_lock;
  
  	/* GC inode list */
  	struct list_head	ns_gc_inodes;
  
  	/* Inode allocator */
  	u32			ns_next_generation;
  	spinlock_t		ns_next_gen_lock;
  
  	/* Mount options */
  	unsigned long		ns_mount_opt;
  
  	uid_t			ns_resuid;
  	gid_t			ns_resgid;
  	unsigned long		ns_interval;
  	unsigned long		ns_watermark;
  
  	/* Disk layout information (static) */
  	unsigned int		ns_blocksize_bits;
  	unsigned int		ns_blocksize;
  	unsigned long		ns_nsegments;
  	unsigned long		ns_blocks_per_segment;
  	unsigned long		ns_r_segments_percentage;
  	unsigned long		ns_nrsvsegs;
  	unsigned long		ns_first_data_block;
  	int			ns_inode_size;
  	int			ns_first_ino;
  	u32			ns_crc_seed;
  };
  
  #define THE_NILFS_FNS(bit, name)					\
  static inline void set_nilfs_##name(struct the_nilfs *nilfs)		\
  {									\
  	set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);			\
  }									\
  static inline void clear_nilfs_##name(struct the_nilfs *nilfs)		\
  {									\
  	clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);			\
  }									\
  static inline int nilfs_##name(struct the_nilfs *nilfs)			\
  {									\
  	return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);		\
  }
  
  THE_NILFS_FNS(INIT, init)
  THE_NILFS_FNS(DISCONTINUED, discontinued)
  THE_NILFS_FNS(GC_RUNNING, gc_running)
  THE_NILFS_FNS(SB_DIRTY, sb_dirty)
  
  /*
   * Mount option operations
   */
  #define nilfs_clear_opt(nilfs, opt)  \
  	do { (nilfs)->ns_mount_opt &= ~NILFS_MOUNT_##opt; } while (0)
  #define nilfs_set_opt(nilfs, opt)  \
  	do { (nilfs)->ns_mount_opt |= NILFS_MOUNT_##opt; } while (0)
  #define nilfs_test_opt(nilfs, opt) ((nilfs)->ns_mount_opt & NILFS_MOUNT_##opt)
  #define nilfs_write_opt(nilfs, mask, opt)				\
  	do { (nilfs)->ns_mount_opt =					\
  		(((nilfs)->ns_mount_opt & ~NILFS_MOUNT_##mask) |	\
  		 NILFS_MOUNT_##opt);					\
  	} while (0)
  
  /**
   * struct nilfs_root - nilfs root object
   * @cno: checkpoint number
   * @rb_node: red-black tree node
   * @count: refcount of this structure
   * @nilfs: nilfs object
   * @ifile: inode file
   * @inodes_count: number of inodes
   * @blocks_count: number of blocks
   */
  struct nilfs_root {
  	__u64 cno;
  	struct rb_node rb_node;
  
  	atomic_t count;
  	struct the_nilfs *nilfs;
  	struct inode *ifile;
  
  	atomic64_t inodes_count;
  	atomic64_t blocks_count;
  };
  
  /* Special checkpoint number */
  #define NILFS_CPTREE_CURRENT_CNO	0
  
  /* Minimum interval of periodical update of superblocks (in seconds) */
  #define NILFS_SB_FREQ		10
  
  static inline int nilfs_sb_need_update(struct the_nilfs *nilfs)
  {
  	u64 t = get_seconds();
  	return t < nilfs->ns_sbwtime || t > nilfs->ns_sbwtime + NILFS_SB_FREQ;
  }
  
  static inline int nilfs_sb_will_flip(struct the_nilfs *nilfs)
  {
  	int flip_bits = nilfs->ns_sbwcount & 0x0FL;
  	return (flip_bits != 0x08 && flip_bits != 0x0F);
  }
  
  void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
  struct the_nilfs *alloc_nilfs(struct block_device *bdev);
  void destroy_nilfs(struct the_nilfs *nilfs);
  int init_nilfs(struct the_nilfs *nilfs, struct super_block *sb, char *data);
  int load_nilfs(struct the_nilfs *nilfs, struct super_block *sb);
  unsigned long nilfs_nrsvsegs(struct the_nilfs *nilfs, unsigned long nsegs);
  void nilfs_set_nsegments(struct the_nilfs *nilfs, unsigned long nsegs);
  int nilfs_discard_segments(struct the_nilfs *, __u64 *, size_t);
  int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
  struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno);
  struct nilfs_root *nilfs_find_or_create_root(struct the_nilfs *nilfs,
  					     __u64 cno);
  void nilfs_put_root(struct nilfs_root *root);
  int nilfs_near_disk_full(struct the_nilfs *);
  void nilfs_fall_back_super_block(struct the_nilfs *);
  void nilfs_swap_super_block(struct the_nilfs *);
  
  
  static inline void nilfs_get_root(struct nilfs_root *root)
  {
  	atomic_inc(&root->count);
  }
  
  static inline int nilfs_valid_fs(struct the_nilfs *nilfs)
  {
  	unsigned valid_fs;
  
  	down_read(&nilfs->ns_sem);
  	valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
  	up_read(&nilfs->ns_sem);
  	return valid_fs;
  }
  
  static inline void
  nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
  			sector_t *seg_start, sector_t *seg_end)
  {
  	*seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
  	*seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
  	if (segnum == 0)
  		*seg_start = nilfs->ns_first_data_block;
  }
  
  static inline sector_t
  nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
  {
  	return (segnum == 0) ? nilfs->ns_first_data_block :
  		(sector_t)nilfs->ns_blocks_per_segment * segnum;
  }
  
  static inline __u64
  nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
  {
  	sector_t segnum = blocknr;
  
  	sector_div(segnum, nilfs->ns_blocks_per_segment);
  	return segnum;
  }
  
  static inline void
  nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
  			sector_t seg_end)
  {
  	/* terminate the current full segment (used in case of I/O-error) */
  	nilfs->ns_pseg_offset = seg_end - seg_start + 1;
  }
  
  static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
  {
  	/* move forward with a full segment */
  	nilfs->ns_segnum = nilfs->ns_nextnum;
  	nilfs->ns_pseg_offset = 0;
  	nilfs->ns_seg_seq++;
  }
  
  static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
  {
  	__u64 cno;
  
  	spin_lock(&nilfs->ns_last_segment_lock);
  	cno = nilfs->ns_last_cno;
  	spin_unlock(&nilfs->ns_last_segment_lock);
  	return cno;
  }
  
  static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
  {
  	return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
  }
  
  #endif /* _THE_NILFS_H */