the_nilfs.h

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/*
 * 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 <[email protected]>
 *
 */

#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 {
    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 {
    __u64 cno;
    struct rb_node rb_node;

    atomic_t count;
    struct the_nilfs *nilfs;
    struct inode *ifile;

    atomic_t inodes_count;
    atomic_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 */