/*
 * 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;
struct nilfs_sysfs_dev_subgroups;

/* 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_flushed_device: flag indicating if all volatile data was flushed
 * @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_sb_update_freq: interval of periodical update of superblocks (in seconds)
 * @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
 * @ns_dev_kobj: /sys/fs/<nilfs>/<device>
 * @ns_dev_kobj_unregister: completion state
 * @ns_dev_subgroups: <device> subgroups pointer
 */
struct the_nilfs {
        unsigned long           ns_flags;
        int                     ns_flushed_device;

        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;
        unsigned                ns_sb_update_freq;

        /*
         * 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;

        /* /sys/fs/<nilfs>/<device> */
        struct kobject ns_dev_kobj;
        struct completion ns_dev_kobj_unregister;
        struct nilfs_sysfs_dev_subgroups *ns_dev_subgroups;
};

#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
 * @snapshot_kobj: /sys/fs/<nilfs>/<device>/mounted_snapshots/<snapshot>
 * @snapshot_kobj_unregister: completion state for kernel object
 */
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;

        /* /sys/fs/<nilfs>/<device>/mounted_snapshots/<snapshot> */
        struct kobject snapshot_kobj;
        struct completion snapshot_kobj_unregister;
};

/* 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->ns_sb_update_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;
}

static inline int nilfs_flush_device(struct the_nilfs *nilfs)
{
        int err;

        if (!nilfs_test_opt(nilfs, BARRIER) || nilfs->ns_flushed_device)
                return 0;

        nilfs->ns_flushed_device = 1;
        /*
         * the store to ns_flushed_device must not be reordered after
         * blkdev_issue_flush().
         */
        smp_wmb();

        err = blkdev_issue_flush(nilfs->ns_bdev, GFP_KERNEL, NULL);
        if (err != -EIO)
                err = 0;
        return err;
}

#endif /* _THE_NILFS_H */