RT-AC56 3.0.0.4.374.37 core

[tomato.git] / release / src-rt-6.x.4708 / linux / linux-2.6.36 / fs / logfs / logfs.h

/*
 * fs/logfs/logfs.h
 *
 * As should be obvious for Linux kernel code, license is GPLv2
 *
 * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
 *
 * Private header for logfs.
 */
#ifndef FS_LOGFS_LOGFS_H
#define FS_LOGFS_LOGFS_H

#undef __CHECK_ENDIAN__
#define __CHECK_ENDIAN__

#include <linux/btree.h>
#include <linux/crc32.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/mempool.h>
#include <linux/pagemap.h>
#include <linux/mtd/mtd.h>
#include "logfs_abi.h"

#define LOGFS_DEBUG_SUPER       (0x0001)
#define LOGFS_DEBUG_SEGMENT     (0x0002)
#define LOGFS_DEBUG_JOURNAL     (0x0004)
#define LOGFS_DEBUG_DIR         (0x0008)
#define LOGFS_DEBUG_FILE        (0x0010)
#define LOGFS_DEBUG_INODE       (0x0020)
#define LOGFS_DEBUG_READWRITE   (0x0040)
#define LOGFS_DEBUG_GC          (0x0080)
#define LOGFS_DEBUG_GC_NOISY    (0x0100)
#define LOGFS_DEBUG_ALIASES     (0x0200)
#define LOGFS_DEBUG_BLOCKMOVE   (0x0400)
#define LOGFS_DEBUG_ALL         (0xffffffff)

#define LOGFS_DEBUG             (0x01)
/*
 * To enable specific log messages, simply define LOGFS_DEBUG to match any
 * or all of the above.
 */
#ifndef LOGFS_DEBUG
#define LOGFS_DEBUG             (0)
#endif

#define log_cond(cond, fmt, arg...) do {        \
        if (cond)                               \
                printk(KERN_DEBUG fmt, ##arg);  \
} while (0)

#define log_super(fmt, arg...) \
        log_cond(LOGFS_DEBUG & LOGFS_DEBUG_SUPER, fmt, ##arg)
#define log_segment(fmt, arg...) \
        log_cond(LOGFS_DEBUG & LOGFS_DEBUG_SEGMENT, fmt, ##arg)
#define log_journal(fmt, arg...) \
        log_cond(LOGFS_DEBUG & LOGFS_DEBUG_JOURNAL, fmt, ##arg)
#define log_dir(fmt, arg...) \
        log_cond(LOGFS_DEBUG & LOGFS_DEBUG_DIR, fmt, ##arg)
#define log_file(fmt, arg...) \
        log_cond(LOGFS_DEBUG & LOGFS_DEBUG_FILE, fmt, ##arg)
#define log_inode(fmt, arg...) \
        log_cond(LOGFS_DEBUG & LOGFS_DEBUG_INODE, fmt, ##arg)
#define log_readwrite(fmt, arg...) \
        log_cond(LOGFS_DEBUG & LOGFS_DEBUG_READWRITE, fmt, ##arg)
#define log_gc(fmt, arg...) \
        log_cond(LOGFS_DEBUG & LOGFS_DEBUG_GC, fmt, ##arg)
#define log_gc_noisy(fmt, arg...) \
        log_cond(LOGFS_DEBUG & LOGFS_DEBUG_GC_NOISY, fmt, ##arg)
#define log_aliases(fmt, arg...) \
        log_cond(LOGFS_DEBUG & LOGFS_DEBUG_ALIASES, fmt, ##arg)
#define log_blockmove(fmt, arg...) \
        log_cond(LOGFS_DEBUG & LOGFS_DEBUG_BLOCKMOVE, fmt, ##arg)

#define PG_pre_locked           PG_owner_priv_1
#define PagePreLocked(page)     test_bit(PG_pre_locked, &(page)->flags)
#define SetPagePreLocked(page)  set_bit(PG_pre_locked, &(page)->flags)
#define ClearPagePreLocked(page) clear_bit(PG_pre_locked, &(page)->flags)

#define LOGFS_LINK_MAX          (1<<30)

/* Read-only filesystem */
#define LOGFS_SB_FLAG_RO        0x0001
#define LOGFS_SB_FLAG_DIRTY     0x0002
#define LOGFS_SB_FLAG_OBJ_ALIAS 0x0004
#define LOGFS_SB_FLAG_SHUTDOWN  0x0008

/* Write Control Flags */
#define WF_LOCK                 0x01 /* take write lock */
#define WF_WRITE                0x02 /* write block */
#define WF_DELETE               0x04 /* delete old block */

typedef u8 __bitwise level_t;
typedef u8 __bitwise gc_level_t;

#define LEVEL(level) ((__force level_t)(level))
#define GC_LEVEL(gc_level) ((__force gc_level_t)(gc_level))

#define SUBLEVEL(level) ( (void)((level) == LEVEL(1)),  \
                (__force level_t)((__force u8)(level) - 1) )

/**
 * struct logfs_area - area management information
 *
 * @a_sb:                       the superblock this area belongs to
 * @a_is_open:                  1 if the area is currently open, else 0
 * @a_segno:                    segment number of area
 * @a_written_bytes:            number of bytes already written back
 * @a_used_bytes:               number of used bytes
 * @a_ops:                      area operations (either journal or ostore)
 * @a_erase_count:              erase count
 * @a_level:                    GC level
 */
struct logfs_area { /* a segment open for writing */
        struct super_block *a_sb;
        int     a_is_open;
        u32     a_segno;
        u32     a_written_bytes;
        u32     a_used_bytes;
        const struct logfs_area_ops *a_ops;
        u32     a_erase_count;
        gc_level_t a_level;
};

/**
 * struct logfs_area_ops - area operations
 *
 * @get_free_segment:           fill area->ofs with the offset of a free segment
 * @get_erase_count:            fill area->erase_count (needs area->ofs)
 * @erase_segment:              erase and setup segment
 */
struct logfs_area_ops {
        void    (*get_free_segment)(struct logfs_area *area);
        void    (*get_erase_count)(struct logfs_area *area);
        int     (*erase_segment)(struct logfs_area *area);
};

/**
 * struct logfs_device_ops - device access operations
 *
 * @readpage:                   read one page (mm page)
 * @writeseg:                   write one segment.  may be a partial segment
 * @erase:                      erase one segment
 * @read:                       read from the device
 * @erase:                      erase part of the device
 * @can_write_buf:              decide whether wbuf can be written to ofs
 */
struct logfs_device_ops {
        struct page *(*find_first_sb)(struct super_block *sb, u64 *ofs);
        struct page *(*find_last_sb)(struct super_block *sb, u64 *ofs);
        int (*write_sb)(struct super_block *sb, struct page *page);
        int (*readpage)(void *_sb, struct page *page);
        void (*writeseg)(struct super_block *sb, u64 ofs, size_t len);
        int (*erase)(struct super_block *sb, loff_t ofs, size_t len,
                        int ensure_write);
        int (*can_write_buf)(struct super_block *sb, u64 ofs);
        void (*sync)(struct super_block *sb);
        void (*put_device)(struct super_block *sb);
};

/**
 * struct candidate_list - list of similar candidates
 */
struct candidate_list {
        struct rb_root rb_tree;
        int count;
        int maxcount;
        int sort_by_ec;
};

/**
 * struct gc_candidate - "candidate" segment to be garbage collected next
 *
 * @list:                       list (either free of low)
 * @segno:                      segment number
 * @valid:                      number of valid bytes
 * @erase_count:                erase count of segment
 * @dist:                       distance from tree root
 *
 * Candidates can be on two lists.  The free list contains electees rather
 * than candidates - segments that no longer contain any valid data.  The
 * low list contains candidates to be picked for GC.  It should be kept
 * short.  It is not required to always pick a perfect candidate.  In the
 * worst case GC will have to move more data than absolutely necessary.
 */
struct gc_candidate {
        struct rb_node rb_node;
        struct candidate_list *list;
        u32     segno;
        u32     valid;
        u32     erase_count;
        u8      dist;
};

/**
 * struct logfs_journal_entry - temporary structure used during journal scan
 *
 * @used:
 * @version:                    normalized version
 * @len:                        length
 * @offset:                     offset
 */
struct logfs_journal_entry {
        int used;
        s16 version;
        u16 len;
        u16 datalen;
        u64 offset;
};

enum transaction_state {
        CREATE_1 = 1,
        CREATE_2,
        UNLINK_1,
        UNLINK_2,
        CROSS_RENAME_1,
        CROSS_RENAME_2,
        TARGET_RENAME_1,
        TARGET_RENAME_2,
        TARGET_RENAME_3
};

/**
 * struct logfs_transaction - essential fields to support atomic dirops
 *
 * @ino:                        target inode
 * @dir:                        inode of directory containing dentry
 * @pos:                        pos of dentry in directory
 */
struct logfs_transaction {
        enum transaction_state state;
        u64      ino;
        u64      dir;
        u64      pos;
};

/**
 * struct logfs_shadow - old block in the shadow of a not-yet-committed new one
 * @old_ofs:                    offset of old block on medium
 * @new_ofs:                    offset of new block on medium
 * @ino:                        inode number
 * @bix:                        block index
 * @old_len:                    size of old block, including header
 * @new_len:                    size of new block, including header
 * @level:                      block level
 */
struct logfs_shadow {
        u64 old_ofs;
        u64 new_ofs;
        u64 ino;
        u64 bix;
        int old_len;
        int new_len;
        gc_level_t gc_level;
};

/**
 * struct shadow_tree
 * @new:                        shadows where old_ofs==0, indexed by new_ofs
 * @old:                        shadows where old_ofs!=0, indexed by old_ofs
 * @segment_map:                bitfield of segments containing shadows
 * @no_shadowed_segment:        number of segments containing shadows
 */
struct shadow_tree {
        struct btree_head64 new;
        struct btree_head64 old;
        struct btree_head32 segment_map;
        int no_shadowed_segments;
};

struct object_alias_item {
        struct list_head list;
        __be64 val;
        int child_no;
};

/**
 * struct logfs_block - contains any block state
 * @type:                       indirect block or inode
 * @full:                       number of fully populated children
 * @partial:                    number of partially populated children
 *
 * Most blocks are directly represented by page cache pages.  But when a block
 * becomes dirty, is part of a transaction, contains aliases or is otherwise
 * special, a struct logfs_block is allocated to track the additional state.
 * Inodes are very similar to indirect blocks, so they can also get one of
 * these structures added when appropriate.
 */
#define BLOCK_INDIRECT  1       /* Indirect block */
#define BLOCK_INODE     2       /* Inode */
struct logfs_block_ops;
struct logfs_block {
        struct list_head alias_list;
        struct list_head item_list;
        struct super_block *sb;
        u64 ino;
        u64 bix;
        level_t level;
        struct page *page;
        struct inode *inode;
        struct logfs_transaction *ta;
        unsigned long alias_map[LOGFS_BLOCK_FACTOR / BITS_PER_LONG];
        struct logfs_block_ops *ops;
        int full;
        int partial;
        int reserved_bytes;
};

typedef int write_alias_t(struct super_block *sb, u64 ino, u64 bix,
                level_t level, int child_no, __be64 val);
struct logfs_block_ops {
        void    (*write_block)(struct logfs_block *block);
        void    (*free_block)(struct super_block *sb, struct logfs_block*block);
        int     (*write_alias)(struct super_block *sb,
                        struct logfs_block *block,
                        write_alias_t *write_one_alias);
};

#define MAX_JOURNAL_ENTRIES 256

struct logfs_super {
        struct mtd_info *s_mtd;                 /* underlying device */
        struct block_device *s_bdev;            /* underlying device */
        const struct logfs_device_ops *s_devops;/* device access */
        struct inode    *s_master_inode;        /* inode file */
        struct inode    *s_segfile_inode;       /* segment file */
        struct inode *s_mapping_inode;          /* device mapping */
        atomic_t s_pending_writes;              /* outstanting bios */
        long     s_flags;
        mempool_t *s_btree_pool;                /* for btree nodes */
        mempool_t *s_alias_pool;                /* aliases in segment.c */
        u64      s_feature_incompat;
        u64      s_feature_ro_compat;
        u64      s_feature_compat;
        u64      s_feature_flags;
        u64      s_sb_ofs[2];
        struct page *s_erase_page;              /* for dev_bdev.c */
        /* alias.c fields */
        struct btree_head32 s_segment_alias;    /* remapped segments */
        int      s_no_object_aliases;
        struct list_head s_object_alias;        /* remapped objects */
        struct btree_head128 s_object_alias_tree; /* remapped objects */
        struct mutex s_object_alias_mutex;
        /* dir.c fields */
        struct mutex s_dirop_mutex;             /* for creat/unlink/rename */
        u64      s_victim_ino;                  /* used for atomic dir-ops */
        u64      s_rename_dir;                  /* source directory ino */
        u64      s_rename_pos;                  /* position of source dd */
        /* gc.c fields */
        long     s_segsize;                     /* size of a segment */
        int      s_segshift;                    /* log2 of segment size */
        long     s_segmask;                     /* 1 << s_segshift - 1 */
        long     s_no_segs;                     /* segments on device */
        long     s_no_journal_segs;             /* segments used for journal */
        long     s_no_blocks;                   /* blocks per segment */
        long     s_writesize;                   /* minimum write size */
        int      s_writeshift;                  /* log2 of write size */
        u64      s_size;                        /* filesystem size */
        struct logfs_area *s_area[LOGFS_NO_AREAS];      /* open segment array */
        u64      s_gec;                         /* global erase count */
        u64      s_wl_gec_ostore;               /* time of last wl event */
        u64      s_wl_gec_journal;              /* time of last wl event */
        u64      s_sweeper;                     /* current sweeper pos */
        u8       s_ifile_levels;                /* max level of ifile */
        u8       s_iblock_levels;               /* max level of regular files */
        u8       s_data_levels;                 /* # of segments to leaf block*/
        u8       s_total_levels;                /* sum of above three */
        struct btree_head32 s_cand_tree;        /* all candidates */
        struct candidate_list s_free_list;      /* 100% free segments */
        struct candidate_list s_reserve_list;   /* Bad segment reserve */
        struct candidate_list s_low_list[LOGFS_NO_AREAS];/* good candidates */
        struct candidate_list s_ec_list;        /* wear level candidates */
        struct btree_head32 s_reserved_segments;/* sb, journal, bad, etc. */
        /* inode.c fields */
        u64      s_last_ino;                    /* highest ino used */
        long     s_inos_till_wrap;
        u32      s_generation;                  /* i_generation for new files */
        struct list_head s_freeing_list;        /* inodes being freed */
        /* journal.c fields */
        struct mutex s_journal_mutex;
        void    *s_je;                          /* journal entry to compress */
        void    *s_compressed_je;               /* block to write to journal */
        u32      s_journal_seg[LOGFS_JOURNAL_SEGS]; /* journal segments */
        u32      s_journal_ec[LOGFS_JOURNAL_SEGS]; /* journal erasecounts */
        u64      s_last_version;
        struct logfs_area *s_journal_area;      /* open journal segment */
        __be64  s_je_array[MAX_JOURNAL_ENTRIES];
        int     s_no_je;

        int      s_sum_index;                   /* for the 12 summaries */
        struct shadow_tree s_shadow_tree;
        int      s_je_fill;                     /* index of current je */
        /* readwrite.c fields */
        struct mutex s_write_mutex;
        int      s_lock_count;
        mempool_t *s_block_pool;                /* struct logfs_block pool */
        mempool_t *s_shadow_pool;               /* struct logfs_shadow pool */
        struct list_head s_writeback_list;      /* writeback pages */
        /*
         * Space accounting:
         * - s_used_bytes specifies space used to store valid data objects.
         * - s_dirty_used_bytes is space used to store non-committed data
         *   objects.  Those objects have already been written themselves,
         *   but they don't become valid until all indirect blocks up to the
         *   journal have been written as well.
         * - s_dirty_free_bytes is space used to store the old copy of a
         *   replaced object, as long as the replacement is non-committed.
         *   In other words, it is the amount of space freed when all dirty
         *   blocks are written back.
         * - s_free_bytes is the amount of free space available for any
         *   purpose.
         * - s_root_reserve is the amount of free space available only to
         *   the root user.  Non-privileged users can no longer write once
         *   this watermark has been reached.
         * - s_speed_reserve is space which remains unused to speed up
         *   garbage collection performance.
         * - s_dirty_pages is the space reserved for currently dirty pages.
         *   It is a pessimistic estimate, so some/most will get freed on
         *   page writeback.
         *
         * s_used_bytes + s_free_bytes + s_speed_reserve = total usable size
         */
        u64      s_free_bytes;
        u64      s_used_bytes;
        u64      s_dirty_free_bytes;
        u64      s_dirty_used_bytes;
        u64      s_root_reserve;
        u64      s_speed_reserve;
        u64      s_dirty_pages;
        /* Bad block handling:
         * - s_bad_seg_reserve is a number of segments usually kept
         *   free.  When encountering bad blocks, the affected segment's data
         *   is _temporarily_ moved to a reserved segment.
         * - s_bad_segments is the number of known bad segments.
         */
        u32      s_bad_seg_reserve;
        u32      s_bad_segments;
};

/**
 * struct logfs_inode - in-memory inode
 *
 * @vfs_inode:                  struct inode
 * @li_data:                    data pointers
 * @li_used_bytes:              number of used bytes
 * @li_freeing_list:            used to track inodes currently being freed
 * @li_flags:                   inode flags
 * @li_refcount:                number of internal (GC-induced) references
 */
struct logfs_inode {
        struct inode vfs_inode;
        u64     li_data[LOGFS_EMBEDDED_FIELDS];
        u64     li_used_bytes;
        struct list_head li_freeing_list;
        struct logfs_block *li_block;
        u32     li_flags;
        u8      li_height;
        int     li_refcount;
};

#define journal_for_each(__i) for (__i = 0; __i < LOGFS_JOURNAL_SEGS; __i++)
#define for_each_area(__i) for (__i = 0; __i < LOGFS_NO_AREAS; __i++)
#define for_each_area_down(__i) for (__i = LOGFS_NO_AREAS - 1; __i >= 0; __i--)

/* compr.c */
int logfs_compress(void *in, void *out, size_t inlen, size_t outlen);
int logfs_uncompress(void *in, void *out, size_t inlen, size_t outlen);
int __init logfs_compr_init(void);
void logfs_compr_exit(void);

/* dev_bdev.c */
#ifdef CONFIG_BLOCK
int logfs_get_sb_bdev(struct file_system_type *type, int flags,
                const char *devname, struct vfsmount *mnt);
#else
static inline int logfs_get_sb_bdev(struct file_system_type *type, int flags,
                const char *devname, struct vfsmount *mnt)
{
        return -ENODEV;
}
#endif

/* dev_mtd.c */
#ifdef CONFIG_MTD
int logfs_get_sb_mtd(struct file_system_type *type, int flags,
                int mtdnr, struct vfsmount *mnt);
#else
static inline int logfs_get_sb_mtd(struct file_system_type *type, int flags,
                int mtdnr, struct vfsmount *mnt)
{
        return -ENODEV;
}
#endif

/* dir.c */
extern const struct inode_operations logfs_symlink_iops;
extern const struct inode_operations logfs_dir_iops;
extern const struct file_operations logfs_dir_fops;
int logfs_replay_journal(struct super_block *sb);

/* file.c */
extern const struct inode_operations logfs_reg_iops;
extern const struct file_operations logfs_reg_fops;
extern const struct address_space_operations logfs_reg_aops;
int logfs_readpage(struct file *file, struct page *page);
long logfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
int logfs_fsync(struct file *file, int datasync);

/* gc.c */
u32 get_best_cand(struct super_block *sb, struct candidate_list *list, u32 *ec);
void logfs_gc_pass(struct super_block *sb);
int logfs_check_areas(struct super_block *sb);
int logfs_init_gc(struct super_block *sb);
void logfs_cleanup_gc(struct super_block *sb);

/* inode.c */
extern const struct super_operations logfs_super_operations;
struct inode *logfs_iget(struct super_block *sb, ino_t ino);
struct inode *logfs_safe_iget(struct super_block *sb, ino_t ino, int *cookie);
void logfs_safe_iput(struct inode *inode, int cookie);
struct inode *logfs_new_inode(struct inode *dir, int mode);
struct inode *logfs_new_meta_inode(struct super_block *sb, u64 ino);
struct inode *logfs_read_meta_inode(struct super_block *sb, u64 ino);
int logfs_init_inode_cache(void);
void logfs_destroy_inode_cache(void);
void logfs_set_blocks(struct inode *inode, u64 no);
/* these logically belong into inode.c but actually reside in readwrite.c */
int logfs_read_inode(struct inode *inode);
int __logfs_write_inode(struct inode *inode, long flags);
void logfs_evict_inode(struct inode *inode);

/* journal.c */
void logfs_write_anchor(struct super_block *sb);
int logfs_init_journal(struct super_block *sb);
void logfs_cleanup_journal(struct super_block *sb);
int write_alias_journal(struct super_block *sb, u64 ino, u64 bix,
                level_t level, int child_no, __be64 val);
void do_logfs_journal_wl_pass(struct super_block *sb);

/* readwrite.c */
pgoff_t logfs_pack_index(u64 bix, level_t level);
void logfs_unpack_index(pgoff_t index, u64 *bix, level_t *level);
int logfs_inode_write(struct inode *inode, const void *buf, size_t count,
                loff_t bix, long flags, struct shadow_tree *shadow_tree);
int logfs_readpage_nolock(struct page *page);
int logfs_write_buf(struct inode *inode, struct page *page, long flags);
int logfs_delete(struct inode *inode, pgoff_t index,
                struct shadow_tree *shadow_tree);
int logfs_rewrite_block(struct inode *inode, u64 bix, u64 ofs,
                gc_level_t gc_level, long flags);
int logfs_is_valid_block(struct super_block *sb, u64 ofs, u64 ino, u64 bix,
                gc_level_t gc_level);
int logfs_truncate(struct inode *inode, u64 size);
u64 logfs_seek_hole(struct inode *inode, u64 bix);
u64 logfs_seek_data(struct inode *inode, u64 bix);
int logfs_open_segfile(struct super_block *sb);
int logfs_init_rw(struct super_block *sb);
void logfs_cleanup_rw(struct super_block *sb);
void logfs_add_transaction(struct inode *inode, struct logfs_transaction *ta);
void logfs_del_transaction(struct inode *inode, struct logfs_transaction *ta);
void logfs_write_block(struct logfs_block *block, long flags);
int logfs_write_obj_aliases_pagecache(struct super_block *sb);
void logfs_get_segment_entry(struct super_block *sb, u32 segno,
                struct logfs_segment_entry *se);
void logfs_set_segment_used(struct super_block *sb, u64 ofs, int increment);
void logfs_set_segment_erased(struct super_block *sb, u32 segno, u32 ec,
                gc_level_t gc_level);
void logfs_set_segment_reserved(struct super_block *sb, u32 segno);
void logfs_set_segment_unreserved(struct super_block *sb, u32 segno, u32 ec);
struct logfs_block *__alloc_block(struct super_block *sb,
                u64 ino, u64 bix, level_t level);
void __free_block(struct super_block *sb, struct logfs_block *block);
void btree_write_block(struct logfs_block *block);
void initialize_block_counters(struct page *page, struct logfs_block *block,
                __be64 *array, int page_is_empty);
int logfs_exist_block(struct inode *inode, u64 bix);
int get_page_reserve(struct inode *inode, struct page *page);
extern struct logfs_block_ops indirect_block_ops;

/* segment.c */
int logfs_erase_segment(struct super_block *sb, u32 ofs, int ensure_erase);
int wbuf_read(struct super_block *sb, u64 ofs, size_t len, void *buf);
int logfs_segment_read(struct inode *inode, struct page *page, u64 ofs, u64 bix,
                level_t level);
int logfs_segment_write(struct inode *inode, struct page *page,
                struct logfs_shadow *shadow);
int logfs_segment_delete(struct inode *inode, struct logfs_shadow *shadow);
int logfs_load_object_aliases(struct super_block *sb,
                struct logfs_obj_alias *oa, int count);
void move_page_to_btree(struct page *page);
int logfs_init_mapping(struct super_block *sb);
void logfs_sync_area(struct logfs_area *area);
void logfs_sync_segments(struct super_block *sb);
void freeseg(struct super_block *sb, u32 segno);

/* area handling */
int logfs_init_areas(struct super_block *sb);
void logfs_cleanup_areas(struct super_block *sb);
int logfs_open_area(struct logfs_area *area, size_t bytes);
int __logfs_buf_write(struct logfs_area *area, u64 ofs, void *buf, size_t len,
                int use_filler);

static inline int logfs_buf_write(struct logfs_area *area, u64 ofs,
                void *buf, size_t len)
{
        return __logfs_buf_write(area, ofs, buf, len, 0);
}

static inline int logfs_buf_recover(struct logfs_area *area, u64 ofs,
                void *buf, size_t len)
{
        return __logfs_buf_write(area, ofs, buf, len, 1);
}

/* super.c */
struct page *emergency_read_begin(struct address_space *mapping, pgoff_t index);
void emergency_read_end(struct page *page);
void logfs_crash_dump(struct super_block *sb);
void *memchr_inv(const void *s, int c, size_t n);
int logfs_statfs(struct dentry *dentry, struct kstatfs *stats);
int logfs_get_sb_device(struct file_system_type *type, int flags,
                struct mtd_info *mtd, struct block_device *bdev,
                const struct logfs_device_ops *devops, struct vfsmount *mnt);
int logfs_check_ds(struct logfs_disk_super *ds);
int logfs_write_sb(struct super_block *sb);

static inline struct logfs_super *logfs_super(struct super_block *sb)
{
        return sb->s_fs_info;
}

static inline struct logfs_inode *logfs_inode(struct inode *inode)
{
        return container_of(inode, struct logfs_inode, vfs_inode);
}

static inline void logfs_set_ro(struct super_block *sb)
{
        logfs_super(sb)->s_flags |= LOGFS_SB_FLAG_RO;
}

#define LOGFS_BUG(sb) do {                                      \
        struct super_block *__sb = sb;                          \
        logfs_crash_dump(__sb);                                 \
        logfs_super(__sb)->s_flags |= LOGFS_SB_FLAG_RO;         \
        BUG();                                                  \
} while (0)

#define LOGFS_BUG_ON(condition, sb) \
        do { if (unlikely(condition)) LOGFS_BUG((sb)); } while (0)

static inline __be32 logfs_crc32(void *data, size_t len, size_t skip)
{
        return cpu_to_be32(crc32(~0, data+skip, len-skip));
}

static inline u8 logfs_type(struct inode *inode)
{
        return (inode->i_mode >> 12) & 15;
}

static inline pgoff_t logfs_index(struct super_block *sb, u64 pos)
{
        return pos >> sb->s_blocksize_bits;
}

static inline u64 dev_ofs(struct super_block *sb, u32 segno, u32 ofs)
{
        return ((u64)segno << logfs_super(sb)->s_segshift) + ofs;
}

static inline u32 seg_no(struct super_block *sb, u64 ofs)
{
        return ofs >> logfs_super(sb)->s_segshift;
}

static inline u32 seg_ofs(struct super_block *sb, u64 ofs)
{
        return ofs & logfs_super(sb)->s_segmask;
}

static inline u64 seg_align(struct super_block *sb, u64 ofs)
{
        return ofs & ~logfs_super(sb)->s_segmask;
}

static inline struct logfs_block *logfs_block(struct page *page)
{
        return (void *)page->private;
}

static inline level_t shrink_level(gc_level_t __level)
{
        u8 level = (__force u8)__level;

        if (level >= LOGFS_MAX_LEVELS)
                level -= LOGFS_MAX_LEVELS;
        return (__force level_t)level;
}

static inline gc_level_t expand_level(u64 ino, level_t __level)
{
        u8 level = (__force u8)__level;

        if (ino == LOGFS_INO_MASTER) {
                /* ifile has separate areas */
                level += LOGFS_MAX_LEVELS;
        }
        return (__force gc_level_t)level;
}

static inline int logfs_block_shift(struct super_block *sb, level_t level)
{
        level = shrink_level((__force gc_level_t)level);
        return (__force int)level * (sb->s_blocksize_bits - 3);
}

static inline u64 logfs_block_mask(struct super_block *sb, level_t level)
{
        return ~0ull << logfs_block_shift(sb, level);
}

static inline struct logfs_area *get_area(struct super_block *sb,
                gc_level_t gc_level)
{
        return logfs_super(sb)->s_area[(__force u8)gc_level];
}

static inline void logfs_mempool_destroy(mempool_t *pool)
{
        if (pool)
                mempool_destroy(pool);
}

#endif