/*
 * fs/f2fs/segment.h
 *
 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
 *             http://www.samsung.com/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/blkdev.h>
#include <linux/backing-dev.h>

/* constant macro */
#define NULL_SEGNO                      ((unsigned int)(~0))
#define NULL_SECNO                      ((unsigned int)(~0))

#define DEF_RECLAIM_PREFREE_SEGMENTS    5       /* 5% over total segments */
#define DEF_MAX_RECLAIM_PREFREE_SEGMENTS        4096    /* 8GB in maximum */

/* L: Logical segment # in volume, R: Relative segment # in main area */
#define GET_L2R_SEGNO(free_i, segno)    (segno - free_i->start_segno)
#define GET_R2L_SEGNO(free_i, segno)    (segno + free_i->start_segno)

#define IS_DATASEG(t)   (t <= CURSEG_COLD_DATA)
#define IS_NODESEG(t)   (t >= CURSEG_HOT_NODE)

#define IS_CURSEG(sbi, seg)                                             \
        ((seg == CURSEG_I(sbi, CURSEG_HOT_DATA)->segno) ||      \
         (seg == CURSEG_I(sbi, CURSEG_WARM_DATA)->segno) ||     \
         (seg == CURSEG_I(sbi, CURSEG_COLD_DATA)->segno) ||     \
         (seg == CURSEG_I(sbi, CURSEG_HOT_NODE)->segno) ||      \
         (seg == CURSEG_I(sbi, CURSEG_WARM_NODE)->segno) ||     \
         (seg == CURSEG_I(sbi, CURSEG_COLD_NODE)->segno))

#define IS_CURSEC(sbi, secno)                                           \
        ((secno == CURSEG_I(sbi, CURSEG_HOT_DATA)->segno /              \
          sbi->segs_per_sec) || \
         (secno == CURSEG_I(sbi, CURSEG_WARM_DATA)->segno /             \
          sbi->segs_per_sec) || \
         (secno == CURSEG_I(sbi, CURSEG_COLD_DATA)->segno /             \
          sbi->segs_per_sec) || \
         (secno == CURSEG_I(sbi, CURSEG_HOT_NODE)->segno /              \
          sbi->segs_per_sec) || \
         (secno == CURSEG_I(sbi, CURSEG_WARM_NODE)->segno /             \
          sbi->segs_per_sec) || \
         (secno == CURSEG_I(sbi, CURSEG_COLD_NODE)->segno /             \
          sbi->segs_per_sec))   \

#define MAIN_BLKADDR(sbi)       (SM_I(sbi)->main_blkaddr)
#define SEG0_BLKADDR(sbi)       (SM_I(sbi)->seg0_blkaddr)

#define MAIN_SEGS(sbi)  (SM_I(sbi)->main_segments)
#define MAIN_SECS(sbi)  (sbi->total_sections)

#define TOTAL_SEGS(sbi) (SM_I(sbi)->segment_count)
#define TOTAL_BLKS(sbi) (TOTAL_SEGS(sbi) << sbi->log_blocks_per_seg)

#define MAX_BLKADDR(sbi)        (SEG0_BLKADDR(sbi) + TOTAL_BLKS(sbi))
#define SEGMENT_SIZE(sbi)       (1ULL << (sbi->log_blocksize +          \
                                        sbi->log_blocks_per_seg))

#define START_BLOCK(sbi, segno) (SEG0_BLKADDR(sbi) +                    \
         (GET_R2L_SEGNO(FREE_I(sbi), segno) << sbi->log_blocks_per_seg))

#define NEXT_FREE_BLKADDR(sbi, curseg)                                  \
        (START_BLOCK(sbi, curseg->segno) + curseg->next_blkoff)

#define GET_SEGOFF_FROM_SEG0(sbi, blk_addr)     ((blk_addr) - SEG0_BLKADDR(sbi))
#define GET_SEGNO_FROM_SEG0(sbi, blk_addr)                              \
        (GET_SEGOFF_FROM_SEG0(sbi, blk_addr) >> sbi->log_blocks_per_seg)
#define GET_BLKOFF_FROM_SEG0(sbi, blk_addr)                             \
        (GET_SEGOFF_FROM_SEG0(sbi, blk_addr) & (sbi->blocks_per_seg - 1))

#define GET_SEGNO(sbi, blk_addr)                                        \
        (((blk_addr == NULL_ADDR) || (blk_addr == NEW_ADDR)) ?          \
        NULL_SEGNO : GET_L2R_SEGNO(FREE_I(sbi),                 \
                GET_SEGNO_FROM_SEG0(sbi, blk_addr)))
#define GET_SECNO(sbi, segno)                                   \
        ((segno) / sbi->segs_per_sec)
#define GET_ZONENO_FROM_SEGNO(sbi, segno)                               \
        ((segno / sbi->segs_per_sec) / sbi->secs_per_zone)

#define GET_SUM_BLOCK(sbi, segno)                               \
        ((sbi->sm_info->ssa_blkaddr) + segno)

#define GET_SUM_TYPE(footer) ((footer)->entry_type)
#define SET_SUM_TYPE(footer, type) ((footer)->entry_type = type)

#define SIT_ENTRY_OFFSET(sit_i, segno)                                  \
        (segno % sit_i->sents_per_block)
#define SIT_BLOCK_OFFSET(segno)                                 \
        (segno / SIT_ENTRY_PER_BLOCK)
#define START_SEGNO(segno)              \
        (SIT_BLOCK_OFFSET(segno) * SIT_ENTRY_PER_BLOCK)
#define SIT_BLK_CNT(sbi)                        \
        ((MAIN_SEGS(sbi) + SIT_ENTRY_PER_BLOCK - 1) / SIT_ENTRY_PER_BLOCK)
#define f2fs_bitmap_size(nr)                    \
        (BITS_TO_LONGS(nr) * sizeof(unsigned long))

#define SECTOR_FROM_BLOCK(blk_addr)                                     \
        (((sector_t)blk_addr) << F2FS_LOG_SECTORS_PER_BLOCK)
#define SECTOR_TO_BLOCK(sectors)                                        \
        (sectors >> F2FS_LOG_SECTORS_PER_BLOCK)
#define MAX_BIO_BLOCKS(sbi)                                             \
        ((int)min((int)max_hw_blocks(sbi), BIO_MAX_PAGES))

/*
 * indicate a block allocation direction: RIGHT and LEFT.
 * RIGHT means allocating new sections towards the end of volume.
 * LEFT means the opposite direction.
 */
enum {
        ALLOC_RIGHT = 0,
        ALLOC_LEFT
};

/*
 * In the victim_sel_policy->alloc_mode, there are two block allocation modes.
 * LFS writes data sequentially with cleaning operations.
 * SSR (Slack Space Recycle) reuses obsolete space without cleaning operations.
 */
enum {
        LFS = 0,
        SSR
};

/*
 * In the victim_sel_policy->gc_mode, there are two gc, aka cleaning, modes.
 * GC_CB is based on cost-benefit algorithm.
 * GC_GREEDY is based on greedy algorithm.
 */
enum {
        GC_CB = 0,
        GC_GREEDY
};

/*
 * BG_GC means the background cleaning job.
 * FG_GC means the on-demand cleaning job.
 * FORCE_FG_GC means on-demand cleaning job in background.
 */
enum {
        BG_GC = 0,
        FG_GC,
        FORCE_FG_GC,
};

/* for a function parameter to select a victim segment */
struct victim_sel_policy {
        int alloc_mode;                 /* LFS or SSR */
        int gc_mode;                    /* GC_CB or GC_GREEDY */
        unsigned long *dirty_segmap;    /* dirty segment bitmap */
        unsigned int max_search;        /* maximum # of segments to search */
        unsigned int offset;            /* last scanned bitmap offset */
        unsigned int ofs_unit;          /* bitmap search unit */
        unsigned int min_cost;          /* minimum cost */
        unsigned int min_segno;         /* segment # having min. cost */
};

struct seg_entry {
        unsigned int type:6;            /* segment type like CURSEG_XXX_TYPE */
        unsigned int valid_blocks:10;   /* # of valid blocks */
        unsigned int ckpt_valid_blocks:10;      /* # of valid blocks last cp */
        unsigned int padding:6;         /* padding */
        unsigned char *cur_valid_map;   /* validity bitmap of blocks */
        /*
         * # of valid blocks and the validity bitmap stored in the the last
         * checkpoint pack. This information is used by the SSR mode.
         */
        unsigned char *ckpt_valid_map;  /* validity bitmap of blocks last cp */
        unsigned char *discard_map;
        unsigned long long mtime;       /* modification time of the segment */
};

struct sec_entry {
        unsigned int valid_blocks;      /* # of valid blocks in a section */
};

struct segment_allocation {
        void (*allocate_segment)(struct f2fs_sb_info *, int, bool);
};

/*
 * this value is set in page as a private data which indicate that
 * the page is atomically written, and it is in inmem_pages list.
 */
#define ATOMIC_WRITTEN_PAGE             ((unsigned long)-1)

#define IS_ATOMIC_WRITTEN_PAGE(page)                    \
                (page_private(page) == (unsigned long)ATOMIC_WRITTEN_PAGE)

struct inmem_pages {
        struct list_head list;
        struct page *page;
        block_t old_addr;               /* for revoking when fail to commit */
};

struct sit_info {
        const struct segment_allocation *s_ops;

        block_t sit_base_addr;          /* start block address of SIT area */
        block_t sit_blocks;             /* # of blocks used by SIT area */
        block_t written_valid_blocks;   /* # of valid blocks in main area */
        char *sit_bitmap;               /* SIT bitmap pointer */
        unsigned int bitmap_size;       /* SIT bitmap size */

        unsigned long *tmp_map;                 /* bitmap for temporal use */
        unsigned long *dirty_sentries_bitmap;   /* bitmap for dirty sentries */
        unsigned int dirty_sentries;            /* # of dirty sentries */
        unsigned int sents_per_block;           /* # of SIT entries per block */
        struct mutex sentry_lock;               /* to protect SIT cache */
        struct seg_entry *sentries;             /* SIT segment-level cache */
        struct sec_entry *sec_entries;          /* SIT section-level cache */

        /* for cost-benefit algorithm in cleaning procedure */
        unsigned long long elapsed_time;        /* elapsed time after mount */
        unsigned long long mounted_time;        /* mount time */
        unsigned long long min_mtime;           /* min. modification time */
        unsigned long long max_mtime;           /* max. modification time */
};

struct free_segmap_info {
        unsigned int start_segno;       /* start segment number logically */
        unsigned int free_segments;     /* # of free segments */
        unsigned int free_sections;     /* # of free sections */
        spinlock_t segmap_lock;         /* free segmap lock */
        unsigned long *free_segmap;     /* free segment bitmap */
        unsigned long *free_secmap;     /* free section bitmap */
};

/* Notice: The order of dirty type is same with CURSEG_XXX in f2fs.h */
enum dirty_type {
        DIRTY_HOT_DATA,         /* dirty segments assigned as hot data logs */
        DIRTY_WARM_DATA,        /* dirty segments assigned as warm data logs */
        DIRTY_COLD_DATA,        /* dirty segments assigned as cold data logs */
        DIRTY_HOT_NODE,         /* dirty segments assigned as hot node logs */
        DIRTY_WARM_NODE,        /* dirty segments assigned as warm node logs */
        DIRTY_COLD_NODE,        /* dirty segments assigned as cold node logs */
        DIRTY,                  /* to count # of dirty segments */
        PRE,                    /* to count # of entirely obsolete segments */
        NR_DIRTY_TYPE
};

struct dirty_seglist_info {
        const struct victim_selection *v_ops;   /* victim selction operation */
        unsigned long *dirty_segmap[NR_DIRTY_TYPE];
        struct mutex seglist_lock;              /* lock for segment bitmaps */
        int nr_dirty[NR_DIRTY_TYPE];            /* # of dirty segments */
        unsigned long *victim_secmap;           /* background GC victims */
};

/* victim selection function for cleaning and SSR */
struct victim_selection {
        int (*get_victim)(struct f2fs_sb_info *, unsigned int *,
                                                        int, int, char);
};

/* for active log information */
struct curseg_info {
        struct mutex curseg_mutex;              /* lock for consistency */
        struct f2fs_summary_block *sum_blk;     /* cached summary block */
        struct rw_semaphore journal_rwsem;      /* protect journal area */
        struct f2fs_journal *journal;           /* cached journal info */
        unsigned char alloc_type;               /* current allocation type */
        unsigned int segno;                     /* current segment number */
        unsigned short next_blkoff;             /* next block offset to write */
        unsigned int zone;                      /* current zone number */
        unsigned int next_segno;                /* preallocated segment */
};

struct sit_entry_set {
        struct list_head set_list;      /* link with all sit sets */
        unsigned int start_segno;       /* start segno of sits in set */
        unsigned int entry_cnt;         /* the # of sit entries in set */
};

/*
 * inline functions
 */
static inline struct curseg_info *CURSEG_I(struct f2fs_sb_info *sbi, int type)
{
        return (struct curseg_info *)(SM_I(sbi)->curseg_array + type);
}

static inline struct seg_entry *get_seg_entry(struct f2fs_sb_info *sbi,
                                                unsigned int segno)
{
        struct sit_info *sit_i = SIT_I(sbi);
        return &sit_i->sentries[segno];
}

static inline struct sec_entry *get_sec_entry(struct f2fs_sb_info *sbi,
                                                unsigned int segno)
{
        struct sit_info *sit_i = SIT_I(sbi);
        return &sit_i->sec_entries[GET_SECNO(sbi, segno)];
}

static inline unsigned int get_valid_blocks(struct f2fs_sb_info *sbi,
                                unsigned int segno, int section)
{
        /*
         * In order to get # of valid blocks in a section instantly from many
         * segments, f2fs manages two counting structures separately.
         */
        if (section > 1)
                return get_sec_entry(sbi, segno)->valid_blocks;
        else
                return get_seg_entry(sbi, segno)->valid_blocks;
}

static inline void seg_info_from_raw_sit(struct seg_entry *se,
                                        struct f2fs_sit_entry *rs)
{
        se->valid_blocks = GET_SIT_VBLOCKS(rs);
        se->ckpt_valid_blocks = GET_SIT_VBLOCKS(rs);
        memcpy(se->cur_valid_map, rs->valid_map, SIT_VBLOCK_MAP_SIZE);
        memcpy(se->ckpt_valid_map, rs->valid_map, SIT_VBLOCK_MAP_SIZE);
        se->type = GET_SIT_TYPE(rs);
        se->mtime = le64_to_cpu(rs->mtime);
}

static inline void seg_info_to_raw_sit(struct seg_entry *se,
                                        struct f2fs_sit_entry *rs)
{
        unsigned short raw_vblocks = (se->type << SIT_VBLOCKS_SHIFT) |
                                        se->valid_blocks;
        rs->vblocks = cpu_to_le16(raw_vblocks);
        memcpy(rs->valid_map, se->cur_valid_map, SIT_VBLOCK_MAP_SIZE);
        memcpy(se->ckpt_valid_map, rs->valid_map, SIT_VBLOCK_MAP_SIZE);
        se->ckpt_valid_blocks = se->valid_blocks;
        rs->mtime = cpu_to_le64(se->mtime);
}

static inline unsigned int find_next_inuse(struct free_segmap_info *free_i,
                unsigned int max, unsigned int segno)
{
        unsigned int ret;
        spin_lock(&free_i->segmap_lock);
        ret = find_next_bit(free_i->free_segmap, max, segno);
        spin_unlock(&free_i->segmap_lock);
        return ret;
}

static inline void __set_free(struct f2fs_sb_info *sbi, unsigned int segno)
{
        struct free_segmap_info *free_i = FREE_I(sbi);
        unsigned int secno = segno / sbi->segs_per_sec;
        unsigned int start_segno = secno * sbi->segs_per_sec;
        unsigned int next;

        spin_lock(&free_i->segmap_lock);
        clear_bit(segno, free_i->free_segmap);
        free_i->free_segments++;

        next = find_next_bit(free_i->free_segmap,
                        start_segno + sbi->segs_per_sec, start_segno);
        if (next >= start_segno + sbi->segs_per_sec) {
                clear_bit(secno, free_i->free_secmap);
                free_i->free_sections++;
        }
        spin_unlock(&free_i->segmap_lock);
}

static inline void __set_inuse(struct f2fs_sb_info *sbi,
                unsigned int segno)
{
        struct free_segmap_info *free_i = FREE_I(sbi);
        unsigned int secno = segno / sbi->segs_per_sec;
        set_bit(segno, free_i->free_segmap);
        free_i->free_segments--;
        if (!test_and_set_bit(secno, free_i->free_secmap))
                free_i->free_sections--;
}

static inline void __set_test_and_free(struct f2fs_sb_info *sbi,
                unsigned int segno)
{
        struct free_segmap_info *free_i = FREE_I(sbi);
        unsigned int secno = segno / sbi->segs_per_sec;
        unsigned int start_segno = secno * sbi->segs_per_sec;
        unsigned int next;

        spin_lock(&free_i->segmap_lock);
        if (test_and_clear_bit(segno, free_i->free_segmap)) {
                free_i->free_segments++;

                next = find_next_bit(free_i->free_segmap,
                                start_segno + sbi->segs_per_sec, start_segno);
                if (next >= start_segno + sbi->segs_per_sec) {
                        if (test_and_clear_bit(secno, free_i->free_secmap))
                                free_i->free_sections++;
                }
        }
        spin_unlock(&free_i->segmap_lock);
}

static inline void __set_test_and_inuse(struct f2fs_sb_info *sbi,
                unsigned int segno)
{
        struct free_segmap_info *free_i = FREE_I(sbi);
        unsigned int secno = segno / sbi->segs_per_sec;
        spin_lock(&free_i->segmap_lock);
        if (!test_and_set_bit(segno, free_i->free_segmap)) {
                free_i->free_segments--;
                if (!test_and_set_bit(secno, free_i->free_secmap))
                        free_i->free_sections--;
        }
        spin_unlock(&free_i->segmap_lock);
}

static inline void get_sit_bitmap(struct f2fs_sb_info *sbi,
                void *dst_addr)
{
        struct sit_info *sit_i = SIT_I(sbi);
        memcpy(dst_addr, sit_i->sit_bitmap, sit_i->bitmap_size);
}

static inline block_t written_block_count(struct f2fs_sb_info *sbi)
{
        return SIT_I(sbi)->written_valid_blocks;
}

static inline unsigned int free_segments(struct f2fs_sb_info *sbi)
{
        return FREE_I(sbi)->free_segments;
}

static inline int reserved_segments(struct f2fs_sb_info *sbi)
{
        return SM_I(sbi)->reserved_segments;
}

static inline unsigned int free_sections(struct f2fs_sb_info *sbi)
{
        return FREE_I(sbi)->free_sections;
}

static inline unsigned int prefree_segments(struct f2fs_sb_info *sbi)
{
        return DIRTY_I(sbi)->nr_dirty[PRE];
}

static inline unsigned int dirty_segments(struct f2fs_sb_info *sbi)
{
        return DIRTY_I(sbi)->nr_dirty[DIRTY_HOT_DATA] +
                DIRTY_I(sbi)->nr_dirty[DIRTY_WARM_DATA] +
                DIRTY_I(sbi)->nr_dirty[DIRTY_COLD_DATA] +
                DIRTY_I(sbi)->nr_dirty[DIRTY_HOT_NODE] +
                DIRTY_I(sbi)->nr_dirty[DIRTY_WARM_NODE] +
                DIRTY_I(sbi)->nr_dirty[DIRTY_COLD_NODE];
}

static inline int overprovision_segments(struct f2fs_sb_info *sbi)
{
        return SM_I(sbi)->ovp_segments;
}

static inline int overprovision_sections(struct f2fs_sb_info *sbi)
{
        return ((unsigned int) overprovision_segments(sbi)) / sbi->segs_per_sec;
}

static inline int reserved_sections(struct f2fs_sb_info *sbi)
{
        return ((unsigned int) reserved_segments(sbi)) / sbi->segs_per_sec;
}

static inline bool need_SSR(struct f2fs_sb_info *sbi)
{
        int node_secs = get_blocktype_secs(sbi, F2FS_DIRTY_NODES);
        int dent_secs = get_blocktype_secs(sbi, F2FS_DIRTY_DENTS);

        if (test_opt(sbi, LFS))
                return false;

        return free_sections(sbi) <= (node_secs + 2 * dent_secs +
                                                reserved_sections(sbi) + 1);
}

static inline bool has_not_enough_free_secs(struct f2fs_sb_info *sbi,
                                        int freed, int needed)
{
        int node_secs = get_blocktype_secs(sbi, F2FS_DIRTY_NODES);
        int dent_secs = get_blocktype_secs(sbi, F2FS_DIRTY_DENTS);

        node_secs += get_blocktype_secs(sbi, F2FS_DIRTY_IMETA);

        if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
                return false;

        return (free_sections(sbi) + freed) <=
                (node_secs + 2 * dent_secs + reserved_sections(sbi) + needed);
}

static inline bool excess_prefree_segs(struct f2fs_sb_info *sbi)
{
        return prefree_segments(sbi) > SM_I(sbi)->rec_prefree_segments;
}

static inline int utilization(struct f2fs_sb_info *sbi)
{
        return div_u64((u64)valid_user_blocks(sbi) * 100,
                                        sbi->user_block_count);
}

/*
 * Sometimes f2fs may be better to drop out-of-place update policy.
 * And, users can control the policy through sysfs entries.
 * There are five policies with triggering conditions as follows.
 * F2FS_IPU_FORCE - all the time,
 * F2FS_IPU_SSR - if SSR mode is activated,
 * F2FS_IPU_UTIL - if FS utilization is over threashold,
 * F2FS_IPU_SSR_UTIL - if SSR mode is activated and FS utilization is over
 *                     threashold,
 * F2FS_IPU_FSYNC - activated in fsync path only for high performance flash
 *                     storages. IPU will be triggered only if the # of dirty
 *                     pages over min_fsync_blocks.
 * F2FS_IPUT_DISABLE - disable IPU. (=default option)
 */
#define DEF_MIN_IPU_UTIL        70
#define DEF_MIN_FSYNC_BLOCKS    8

enum {
        F2FS_IPU_FORCE,
        F2FS_IPU_SSR,
        F2FS_IPU_UTIL,
        F2FS_IPU_SSR_UTIL,
        F2FS_IPU_FSYNC,
};

static inline bool need_inplace_update(struct inode *inode)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        unsigned int policy = SM_I(sbi)->ipu_policy;

        /* IPU can be done only for the user data */
        if (S_ISDIR(inode->i_mode) || f2fs_is_atomic_file(inode))
                return false;

        if (test_opt(sbi, LFS))
                return false;

        if (policy & (0x1 << F2FS_IPU_FORCE))
                return true;
        if (policy & (0x1 << F2FS_IPU_SSR) && need_SSR(sbi))
                return true;
        if (policy & (0x1 << F2FS_IPU_UTIL) &&
                        utilization(sbi) > SM_I(sbi)->min_ipu_util)
                return true;
        if (policy & (0x1 << F2FS_IPU_SSR_UTIL) && need_SSR(sbi) &&
                        utilization(sbi) > SM_I(sbi)->min_ipu_util)
                return true;

        /* this is only set during fdatasync */
        if (policy & (0x1 << F2FS_IPU_FSYNC) &&
                        is_inode_flag_set(inode, FI_NEED_IPU))
                return true;

        return false;
}

static inline unsigned int curseg_segno(struct f2fs_sb_info *sbi,
                int type)
{
        struct curseg_info *curseg = CURSEG_I(sbi, type);
        return curseg->segno;
}

static inline unsigned char curseg_alloc_type(struct f2fs_sb_info *sbi,
                int type)
{
        struct curseg_info *curseg = CURSEG_I(sbi, type);
        return curseg->alloc_type;
}

static inline unsigned short curseg_blkoff(struct f2fs_sb_info *sbi, int type)
{
        struct curseg_info *curseg = CURSEG_I(sbi, type);
        return curseg->next_blkoff;
}

static inline void check_seg_range(struct f2fs_sb_info *sbi, unsigned int segno)
{
        f2fs_bug_on(sbi, segno > TOTAL_SEGS(sbi) - 1);
}

static inline void verify_block_addr(struct f2fs_sb_info *sbi, block_t blk_addr)
{
        BUG_ON(blk_addr < SEG0_BLKADDR(sbi)
                        || blk_addr >= MAX_BLKADDR(sbi));
}

/*
 * Summary block is always treated as an invalid block
 */
static inline void check_block_count(struct f2fs_sb_info *sbi,
                int segno, struct f2fs_sit_entry *raw_sit)
{
#ifdef CONFIG_F2FS_CHECK_FS
        bool is_valid  = test_bit_le(0, raw_sit->valid_map) ? true : false;
        int valid_blocks = 0;
        int cur_pos = 0, next_pos;

        /* check bitmap with valid block count */
        do {
                if (is_valid) {
                        next_pos = find_next_zero_bit_le(&raw_sit->valid_map,
                                        sbi->blocks_per_seg,
                                        cur_pos);
                        valid_blocks += next_pos - cur_pos;
                } else
                        next_pos = find_next_bit_le(&raw_sit->valid_map,
                                        sbi->blocks_per_seg,
                                        cur_pos);
                cur_pos = next_pos;
                is_valid = !is_valid;
        } while (cur_pos < sbi->blocks_per_seg);
        BUG_ON(GET_SIT_VBLOCKS(raw_sit) != valid_blocks);
#endif
        /* check segment usage, and check boundary of a given segment number */
        f2fs_bug_on(sbi, GET_SIT_VBLOCKS(raw_sit) > sbi->blocks_per_seg
                                        || segno > TOTAL_SEGS(sbi) - 1);
}

static inline pgoff_t current_sit_addr(struct f2fs_sb_info *sbi,
                                                unsigned int start)
{
        struct sit_info *sit_i = SIT_I(sbi);
        unsigned int offset = SIT_BLOCK_OFFSET(start);
        block_t blk_addr = sit_i->sit_base_addr + offset;

        check_seg_range(sbi, start);

        /* calculate sit block address */
        if (f2fs_test_bit(offset, sit_i->sit_bitmap))
                blk_addr += sit_i->sit_blocks;

        return blk_addr;
}

static inline pgoff_t next_sit_addr(struct f2fs_sb_info *sbi,
                                                pgoff_t block_addr)
{
        struct sit_info *sit_i = SIT_I(sbi);
        block_addr -= sit_i->sit_base_addr;
        if (block_addr < sit_i->sit_blocks)
                block_addr += sit_i->sit_blocks;
        else
                block_addr -= sit_i->sit_blocks;

        return block_addr + sit_i->sit_base_addr;
}

static inline void set_to_next_sit(struct sit_info *sit_i, unsigned int start)
{
        unsigned int block_off = SIT_BLOCK_OFFSET(start);

        f2fs_change_bit(block_off, sit_i->sit_bitmap);
}

static inline unsigned long long get_mtime(struct f2fs_sb_info *sbi)
{
        struct sit_info *sit_i = SIT_I(sbi);
        return sit_i->elapsed_time + CURRENT_TIME_SEC.tv_sec -
                                                sit_i->mounted_time;
}

static inline void set_summary(struct f2fs_summary *sum, nid_t nid,
                        unsigned int ofs_in_node, unsigned char version)
{
        sum->nid = cpu_to_le32(nid);
        sum->ofs_in_node = cpu_to_le16(ofs_in_node);
        sum->version = version;
}

static inline block_t start_sum_block(struct f2fs_sb_info *sbi)
{
        return __start_cp_addr(sbi) +
                le32_to_cpu(F2FS_CKPT(sbi)->cp_pack_start_sum);
}

static inline block_t sum_blk_addr(struct f2fs_sb_info *sbi, int base, int type)
{
        return __start_cp_addr(sbi) +
                le32_to_cpu(F2FS_CKPT(sbi)->cp_pack_total_block_count)
                                - (base + 1) + type;
}

static inline bool sec_usage_check(struct f2fs_sb_info *sbi, unsigned int secno)
{
        if (IS_CURSEC(sbi, secno) || (sbi->cur_victim_sec == secno))
                return true;
        return false;
}

static inline unsigned int max_hw_blocks(struct f2fs_sb_info *sbi)
{
        struct block_device *bdev = sbi->sb->s_bdev;
        struct request_queue *q = bdev_get_queue(bdev);
        return SECTOR_TO_BLOCK(queue_max_sectors(q));
}

/*
 * It is very important to gather dirty pages and write at once, so that we can
 * submit a big bio without interfering other data writes.
 * By default, 512 pages for directory data,
 * 512 pages (2MB) * 3 for three types of nodes, and
 * max_bio_blocks for meta are set.
 */
static inline int nr_pages_to_skip(struct f2fs_sb_info *sbi, int type)
{
        if (sbi->sb->s_bdi->wb.dirty_exceeded)
                return 0;

        if (type == DATA)
                return sbi->blocks_per_seg;
        else if (type == NODE)
                return 8 * sbi->blocks_per_seg;
        else if (type == META)
                return 8 * MAX_BIO_BLOCKS(sbi);
        else
                return 0;
}

/*
 * When writing pages, it'd better align nr_to_write for segment size.
 */
static inline long nr_pages_to_write(struct f2fs_sb_info *sbi, int type,
                                        struct writeback_control *wbc)
{
        long nr_to_write, desired;

        if (wbc->sync_mode != WB_SYNC_NONE)
                return 0;

        nr_to_write = wbc->nr_to_write;

        if (type == NODE)
                desired = 2 * max_hw_blocks(sbi);
        else
                desired = MAX_BIO_BLOCKS(sbi);

        wbc->nr_to_write = desired;
        return desired - nr_to_write;
}