/* SPDX-License-Identifier: GPL-2.0 */
/*
 * fs/f2fs/gc.h
 *
 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
 *             http://www.samsung.com/
 */
#define GC_THREAD_MIN_WB_PAGES          1       /*
                                                 * a threshold to determine
                                                 * whether IO subsystem is idle
                                                 * or not
                                                 */
#define DEF_GC_THREAD_URGENT_SLEEP_TIME 500     /* 500 ms */
#define DEF_GC_THREAD_MIN_SLEEP_TIME    30000   /* milliseconds */
#define DEF_GC_THREAD_MAX_SLEEP_TIME    60000
#define DEF_GC_THREAD_NOGC_SLEEP_TIME   300000  /* wait 5 min */

/* GC sleep parameters for zoned deivces */
#define DEF_GC_THREAD_MIN_SLEEP_TIME_ZONED      10
#define DEF_GC_THREAD_MAX_SLEEP_TIME_ZONED      20
#define DEF_GC_THREAD_NOGC_SLEEP_TIME_ZONED     60000

/* choose candidates from sections which has age of more than 7 days */
#define DEF_GC_THREAD_AGE_THRESHOLD             (60 * 60 * 24 * 7)
#define DEF_GC_THREAD_CANDIDATE_RATIO           20      /* select 20% oldest sections as candidates */
#define DEF_GC_THREAD_MAX_CANDIDATE_COUNT       10      /* select at most 10 sections as candidates */
#define DEF_GC_THREAD_AGE_WEIGHT                60      /* age weight */
#define DEF_GC_THREAD_VALID_THRESH_RATIO        80      /* do not GC over 80% valid block ratio for one time GC */
#define DEFAULT_ACCURACY_CLASS                  10000   /* accuracy class */

#define LIMIT_INVALID_BLOCK     40 /* percentage over total user space */
#define LIMIT_FREE_BLOCK        40 /* percentage over invalid + free space */

#define LIMIT_NO_ZONED_GC       60 /* percentage over total user space of no gc for zoned devices */
#define LIMIT_BOOST_ZONED_GC    25 /* percentage over total user space of boosted gc for zoned devices */
#define DEF_MIGRATION_WINDOW_GRANULARITY_ZONED  3
#define BOOST_GC_MULTIPLE       5
#define ZONED_PIN_SEC_REQUIRED_COUNT    1

#define DEF_GC_FAILED_PINNED_FILES      2048
#define MAX_GC_FAILED_PINNED_FILES      USHRT_MAX

/* Search max. number of dirty segments to select a victim segment */
#define DEF_MAX_VICTIM_SEARCH 4096 /* covers 8GB */

#define NR_GC_CHECKPOINT_SECS (3)       /* data/node/dentry sections */

struct f2fs_gc_kthread {
        struct task_struct *f2fs_gc_task;
        wait_queue_head_t gc_wait_queue_head;

        /* for gc sleep time */
        unsigned int urgent_sleep_time;
        unsigned int min_sleep_time;
        unsigned int max_sleep_time;
        unsigned int no_gc_sleep_time;

        /* for changing gc mode */
        bool gc_wake;

        /* for GC_MERGE mount option */
        wait_queue_head_t fggc_wq;              /*
                                                 * caller of f2fs_balance_fs()
                                                 * will wait on this wait queue.
                                                 */

        /* for gc control for zoned devices */
        unsigned int no_zoned_gc_percent;
        unsigned int boost_zoned_gc_percent;
        unsigned int valid_thresh_ratio;
        unsigned int boost_gc_multiple;
        unsigned int boost_gc_greedy;
};

struct gc_inode_list {
        struct list_head ilist;
        struct radix_tree_root iroot;
};

struct victim_entry {
        struct rb_node rb_node;         /* rb node located in rb-tree */
        unsigned long long mtime;       /* mtime of section */
        unsigned int segno;             /* segment No. */
        struct list_head list;
};

/*
 * inline functions
 */

/*
 * On a Zoned device zone-capacity can be less than zone-size and if
 * zone-capacity is not aligned to f2fs segment size(2MB), then the segment
 * starting just before zone-capacity has some blocks spanning across the
 * zone-capacity, these blocks are not usable.
 * Such spanning segments can be in free list so calculate the sum of usable
 * blocks in currently free segments including normal and spanning segments.
 */
static inline block_t free_segs_blk_count_zoned(struct f2fs_sb_info *sbi)
{
        block_t free_seg_blks = 0;
        struct free_segmap_info *free_i = FREE_I(sbi);
        int j;

        spin_lock(&free_i->segmap_lock);
        for (j = 0; j < MAIN_SEGS(sbi); j++)
                if (!test_bit(j, free_i->free_segmap))
                        free_seg_blks += f2fs_usable_blks_in_seg(sbi, j);
        spin_unlock(&free_i->segmap_lock);

        return free_seg_blks;
}

static inline block_t free_segs_blk_count(struct f2fs_sb_info *sbi)
{
        if (f2fs_sb_has_blkzoned(sbi))
                return free_segs_blk_count_zoned(sbi);

        return SEGS_TO_BLKS(sbi, free_segments(sbi));
}

static inline block_t free_user_blocks(struct f2fs_sb_info *sbi)
{
        block_t free_blks, ovp_blks;

        free_blks = free_segs_blk_count(sbi);
        ovp_blks = SEGS_TO_BLKS(sbi, overprovision_segments(sbi));

        if (free_blks < ovp_blks)
                return 0;

        return free_blks - ovp_blks;
}

static inline block_t limit_invalid_user_blocks(block_t user_block_count)
{
        return (long)(user_block_count * LIMIT_INVALID_BLOCK) / 100;
}

static inline block_t limit_free_user_blocks(block_t reclaimable_user_blocks)
{
        return (long)(reclaimable_user_blocks * LIMIT_FREE_BLOCK) / 100;
}

static inline void increase_sleep_time(struct f2fs_gc_kthread *gc_th,
                                                        unsigned int *wait)
{
        unsigned int min_time = gc_th->min_sleep_time;
        unsigned int max_time = gc_th->max_sleep_time;

        if (*wait == gc_th->no_gc_sleep_time)
                return;

        if ((long long)*wait + (long long)min_time > (long long)max_time)
                *wait = max_time;
        else
                *wait += min_time;
}

static inline void decrease_sleep_time(struct f2fs_gc_kthread *gc_th,
                                                        unsigned int *wait)
{
        unsigned int min_time = gc_th->min_sleep_time;

        if (*wait == gc_th->no_gc_sleep_time)
                *wait = gc_th->max_sleep_time;

        if ((long long)*wait - (long long)min_time < (long long)min_time)
                *wait = min_time;
        else
                *wait -= min_time;
}

static inline bool has_enough_free_blocks(struct f2fs_sb_info *sbi,
                                                unsigned int limit_perc)
{
        return free_sections(sbi) > ((sbi->total_sections * limit_perc) / 100);
}

static inline bool has_enough_invalid_blocks(struct f2fs_sb_info *sbi)
{
        block_t user_block_count = sbi->user_block_count;
        block_t invalid_user_blocks = user_block_count -
                written_block_count(sbi);
        /*
         * Background GC is triggered with the following conditions.
         * 1. There are a number of invalid blocks.
         * 2. There is not enough free space.
         */
        return (invalid_user_blocks >
                        limit_invalid_user_blocks(user_block_count) &&
                free_user_blocks(sbi) <
                        limit_free_user_blocks(invalid_user_blocks));
}

static inline bool need_to_boost_gc(struct f2fs_sb_info *sbi)
{
        if (f2fs_sb_has_blkzoned(sbi))
                return !has_enough_free_blocks(sbi,
                                sbi->gc_thread->boost_zoned_gc_percent);
        return has_enough_invalid_blocks(sbi);
}