root/fs/f2fs/gc.c
// SPDX-License-Identifier: GPL-2.0
/*
 * fs/f2fs/gc.c
 *
 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
 *             http://www.samsung.com/
 */
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/f2fs_fs.h>
#include <linux/kthread.h>
#include <linux/delay.h>
#include <linux/freezer.h>
#include <linux/sched/signal.h>
#include <linux/random.h>
#include <linux/sched/mm.h>

#include "f2fs.h"
#include "node.h"
#include "segment.h"
#include "gc.h"
#include "iostat.h"
#include <trace/events/f2fs.h>

static struct kmem_cache *victim_entry_slab;

static unsigned int count_bits(const unsigned long *addr,
                                unsigned int offset, unsigned int len);

static int gc_thread_func(void *data)
{
        struct f2fs_sb_info *sbi = data;
        struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
        wait_queue_head_t *wq = &sbi->gc_thread->gc_wait_queue_head;
        wait_queue_head_t *fggc_wq = &sbi->gc_thread->fggc_wq;
        unsigned int wait_ms;
        struct f2fs_gc_control gc_control = {
                .victim_segno = NULL_SEGNO,
                .should_migrate_blocks = false,
                .err_gc_skipped = false,
                .one_time = false };

        wait_ms = gc_th->min_sleep_time;

        set_freezable();
        do {
                bool sync_mode, foreground = false, gc_boost = false;

                wait_event_freezable_timeout(*wq,
                                kthread_should_stop() ||
                                waitqueue_active(fggc_wq) ||
                                gc_th->gc_wake,
                                msecs_to_jiffies(wait_ms));

                if (test_opt(sbi, GC_MERGE) && waitqueue_active(fggc_wq)) {
                        foreground = true;
                        gc_control.one_time = false;
                } else if (f2fs_sb_has_blkzoned(sbi)) {
                        gc_control.one_time = true;
                }

                /* give it a try one time */
                if (gc_th->gc_wake)
                        gc_th->gc_wake = false;

                if (f2fs_readonly(sbi->sb)) {
                        stat_other_skip_bggc_count(sbi);
                        continue;
                }
                if (kthread_should_stop())
                        break;

                if (sbi->sb->s_writers.frozen >= SB_FREEZE_WRITE) {
                        increase_sleep_time(gc_th, &wait_ms);
                        stat_other_skip_bggc_count(sbi);
                        continue;
                }

                if (time_to_inject(sbi, FAULT_CHECKPOINT))
                        f2fs_stop_checkpoint(sbi, false,
                                        STOP_CP_REASON_FAULT_INJECT);

                if (!sb_start_write_trylock(sbi->sb)) {
                        stat_other_skip_bggc_count(sbi);
                        continue;
                }

                /*
                 * [GC triggering condition]
                 * 0. GC is not conducted currently.
                 * 1. There are enough dirty segments.
                 * 2. IO subsystem is idle by checking the # of writeback pages.
                 * 3. IO subsystem is idle by checking the # of requests in
                 *    bdev's request list.
                 *
                 * Note) We have to avoid triggering GCs frequently.
                 * Because it is possible that some segments can be
                 * invalidated soon after by user update or deletion.
                 * So, I'd like to wait some time to collect dirty segments.
                 */
                if (sbi->gc_mode == GC_URGENT_HIGH ||
                                sbi->gc_mode == GC_URGENT_MID) {
                        wait_ms = gc_th->urgent_sleep_time;
                        f2fs_down_write_trace(&sbi->gc_lock, &gc_control.lc);
                        goto do_gc;
                }

                if (foreground) {
                        f2fs_down_write_trace(&sbi->gc_lock, &gc_control.lc);
                        goto do_gc;
                } else if (!f2fs_down_write_trylock_trace(&sbi->gc_lock,
                                                        &gc_control.lc)) {
                        stat_other_skip_bggc_count(sbi);
                        goto next;
                }

                if (!is_idle(sbi, GC_TIME)) {
                        increase_sleep_time(gc_th, &wait_ms);
                        f2fs_up_write_trace(&sbi->gc_lock, &gc_control.lc);
                        stat_io_skip_bggc_count(sbi);
                        goto next;
                }

                if (f2fs_sb_has_blkzoned(sbi)) {
                        if (has_enough_free_blocks(sbi,
                                gc_th->no_zoned_gc_percent)) {
                                wait_ms = gc_th->no_gc_sleep_time;
                                f2fs_up_write_trace(&sbi->gc_lock,
                                                        &gc_control.lc);
                                goto next;
                        }
                        if (wait_ms == gc_th->no_gc_sleep_time)
                                wait_ms = gc_th->max_sleep_time;
                }

                if (need_to_boost_gc(sbi)) {
                        decrease_sleep_time(gc_th, &wait_ms);
                        if (f2fs_sb_has_blkzoned(sbi))
                                gc_boost = true;
                } else {
                        increase_sleep_time(gc_th, &wait_ms);
                }
do_gc:
                stat_inc_gc_call_count(sbi, foreground ?
                                        FOREGROUND : BACKGROUND);

                sync_mode = (F2FS_OPTION(sbi).bggc_mode == BGGC_MODE_SYNC) ||
                        (gc_boost && gc_th->boost_gc_greedy);

                /* foreground GC was been triggered via f2fs_balance_fs() */
                if (foreground && !f2fs_sb_has_blkzoned(sbi))
                        sync_mode = false;

                gc_control.init_gc_type = sync_mode ? FG_GC : BG_GC;
                gc_control.no_bg_gc = foreground;
                gc_control.nr_free_secs = foreground ? 1 : 0;

                /* if return value is not zero, no victim was selected */
                if (f2fs_gc(sbi, &gc_control)) {
                        /* don't bother wait_ms by foreground gc */
                        if (!foreground)
                                wait_ms = gc_th->no_gc_sleep_time;
                } else {
                        /* reset wait_ms to default sleep time */
                        if (wait_ms == gc_th->no_gc_sleep_time)
                                wait_ms = gc_th->min_sleep_time;
                }

                if (foreground)
                        wake_up_all(&gc_th->fggc_wq);

                trace_f2fs_background_gc(sbi->sb, wait_ms,
                                prefree_segments(sbi), free_segments(sbi));

                /* balancing f2fs's metadata periodically */
                f2fs_balance_fs_bg(sbi, true);
next:
                if (sbi->gc_mode != GC_NORMAL) {
                        spin_lock(&sbi->gc_remaining_trials_lock);
                        if (sbi->gc_remaining_trials) {
                                sbi->gc_remaining_trials--;
                                if (!sbi->gc_remaining_trials)
                                        sbi->gc_mode = GC_NORMAL;
                        }
                        spin_unlock(&sbi->gc_remaining_trials_lock);
                }
                sb_end_write(sbi->sb);

        } while (!kthread_should_stop());
        return 0;
}

int f2fs_start_gc_thread(struct f2fs_sb_info *sbi)
{
        struct f2fs_gc_kthread *gc_th;
        dev_t dev = sbi->sb->s_bdev->bd_dev;

        gc_th = f2fs_kmalloc(sbi, sizeof(struct f2fs_gc_kthread), GFP_KERNEL);
        if (!gc_th)
                return -ENOMEM;

        gc_th->urgent_sleep_time = DEF_GC_THREAD_URGENT_SLEEP_TIME;
        gc_th->valid_thresh_ratio = DEF_GC_THREAD_VALID_THRESH_RATIO;
        gc_th->boost_gc_multiple = BOOST_GC_MULTIPLE;
        gc_th->boost_gc_greedy = GC_GREEDY;

        if (f2fs_sb_has_blkzoned(sbi)) {
                gc_th->min_sleep_time = DEF_GC_THREAD_MIN_SLEEP_TIME_ZONED;
                gc_th->max_sleep_time = DEF_GC_THREAD_MAX_SLEEP_TIME_ZONED;
                gc_th->no_gc_sleep_time = DEF_GC_THREAD_NOGC_SLEEP_TIME_ZONED;
                gc_th->no_zoned_gc_percent = LIMIT_NO_ZONED_GC;
                gc_th->boost_zoned_gc_percent = LIMIT_BOOST_ZONED_GC;
        } else {
                gc_th->min_sleep_time = DEF_GC_THREAD_MIN_SLEEP_TIME;
                gc_th->max_sleep_time = DEF_GC_THREAD_MAX_SLEEP_TIME;
                gc_th->no_gc_sleep_time = DEF_GC_THREAD_NOGC_SLEEP_TIME;
                gc_th->no_zoned_gc_percent = 0;
                gc_th->boost_zoned_gc_percent = 0;
        }

        gc_th->gc_wake = false;

        sbi->gc_thread = gc_th;
        init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head);
        init_waitqueue_head(&sbi->gc_thread->fggc_wq);
        sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi,
                        "f2fs_gc-%u:%u", MAJOR(dev), MINOR(dev));
        if (IS_ERR(gc_th->f2fs_gc_task)) {
                int err = PTR_ERR(gc_th->f2fs_gc_task);

                kfree(gc_th);
                sbi->gc_thread = NULL;
                return err;
        }

        set_user_nice(gc_th->f2fs_gc_task,
                        PRIO_TO_NICE(sbi->critical_task_priority));
        return 0;
}

void f2fs_stop_gc_thread(struct f2fs_sb_info *sbi)
{
        struct f2fs_gc_kthread *gc_th = sbi->gc_thread;

        if (!gc_th)
                return;
        kthread_stop(gc_th->f2fs_gc_task);
        wake_up_all(&gc_th->fggc_wq);
        kfree(gc_th);
        sbi->gc_thread = NULL;
}

static int select_gc_type(struct f2fs_sb_info *sbi, int gc_type)
{
        int gc_mode;

        if (gc_type == BG_GC) {
                if (sbi->am.atgc_enabled)
                        gc_mode = GC_AT;
                else
                        gc_mode = GC_CB;
        } else {
                gc_mode = GC_GREEDY;
        }

        switch (sbi->gc_mode) {
        case GC_IDLE_CB:
        case GC_URGENT_LOW:
        case GC_URGENT_MID:
                gc_mode = GC_CB;
                break;
        case GC_IDLE_GREEDY:
        case GC_URGENT_HIGH:
                gc_mode = GC_GREEDY;
                break;
        case GC_IDLE_AT:
                gc_mode = GC_AT;
                break;
        }

        return gc_mode;
}

static void select_policy(struct f2fs_sb_info *sbi, int gc_type,
                        int type, struct victim_sel_policy *p)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);

        if (p->alloc_mode == SSR || p->alloc_mode == AT_SSR) {
                p->gc_mode = GC_GREEDY;
                p->dirty_bitmap = dirty_i->dirty_segmap[type];
                p->max_search = dirty_i->nr_dirty[type];
                p->ofs_unit = 1;
        } else {
                p->gc_mode = select_gc_type(sbi, gc_type);
                p->ofs_unit = SEGS_PER_SEC(sbi);
                if (__is_large_section(sbi)) {
                        p->dirty_bitmap = dirty_i->dirty_secmap;
                        p->max_search = count_bits(p->dirty_bitmap,
                                                0, MAIN_SECS(sbi));
                } else {
                        p->dirty_bitmap = dirty_i->dirty_segmap[DIRTY];
                        p->max_search = dirty_i->nr_dirty[DIRTY];
                }
        }

        /*
         * adjust candidates range, should select all dirty segments for
         * foreground GC and urgent GC cases.
         */
        if (gc_type != FG_GC &&
                        (sbi->gc_mode != GC_URGENT_HIGH) &&
                        (p->gc_mode != GC_AT && p->alloc_mode != AT_SSR) &&
                        p->max_search > sbi->max_victim_search)
                p->max_search = sbi->max_victim_search;

        /* let's select beginning hot/small space first. */
        if (f2fs_need_rand_seg(sbi))
                p->offset = get_random_u32_below(MAIN_SECS(sbi) *
                                                SEGS_PER_SEC(sbi));
        else if (type == CURSEG_HOT_DATA || IS_NODESEG(type))
                p->offset = 0;
        else
                p->offset = SIT_I(sbi)->last_victim[p->gc_mode];
}

static unsigned int get_max_cost(struct f2fs_sb_info *sbi,
                                struct victim_sel_policy *p)
{
        /* SSR allocates in a segment unit */
        if (p->alloc_mode == SSR)
                return BLKS_PER_SEG(sbi);
        else if (p->alloc_mode == AT_SSR)
                return UINT_MAX;

        /* LFS */
        if (p->gc_mode == GC_GREEDY)
                return SEGS_TO_BLKS(sbi, 2 * p->ofs_unit);
        else if (p->gc_mode == GC_CB)
                return UINT_MAX;
        else if (p->gc_mode == GC_AT)
                return UINT_MAX;
        else /* No other gc_mode */
                return 0;
}

static unsigned int check_bg_victims(struct f2fs_sb_info *sbi)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
        unsigned int secno;

        /*
         * If the gc_type is FG_GC, we can select victim segments
         * selected by background GC before.
         * Those segments guarantee they have small valid blocks.
         */
        for_each_set_bit(secno, dirty_i->victim_secmap, MAIN_SECS(sbi)) {
                if (sec_usage_check(sbi, secno))
                        continue;
                clear_bit(secno, dirty_i->victim_secmap);
                return GET_SEG_FROM_SEC(sbi, secno);
        }
        return NULL_SEGNO;
}

static unsigned int get_cb_cost(struct f2fs_sb_info *sbi, unsigned int segno)
{
        struct sit_info *sit_i = SIT_I(sbi);
        unsigned long long mtime = 0;
        unsigned int vblocks;
        unsigned char age = 0;
        unsigned char u;
        unsigned int usable_segs_per_sec = f2fs_usable_segs_in_sec(sbi);

        mtime = f2fs_get_section_mtime(sbi, segno);
        f2fs_bug_on(sbi, mtime == INVALID_MTIME);
        vblocks = get_valid_blocks(sbi, segno, true);
        vblocks = div_u64(vblocks, usable_segs_per_sec);

        u = BLKS_TO_SEGS(sbi, vblocks * 100);

        /* Handle if the system time has changed by the user */
        if (mtime < sit_i->min_mtime)
                sit_i->min_mtime = mtime;
        if (mtime > sit_i->max_mtime)
                sit_i->max_mtime = mtime;
        if (sit_i->max_mtime != sit_i->min_mtime)
                age = 100 - div64_u64(100 * (mtime - sit_i->min_mtime),
                                sit_i->max_mtime - sit_i->min_mtime);

        return UINT_MAX - ((100 * (100 - u) * age) / (100 + u));
}

static inline unsigned int get_gc_cost(struct f2fs_sb_info *sbi,
                        unsigned int segno, struct victim_sel_policy *p,
                        unsigned int valid_thresh_ratio)
{
        if (p->alloc_mode == SSR)
                return get_seg_entry(sbi, segno)->ckpt_valid_blocks;

        if (p->one_time_gc && (valid_thresh_ratio < 100) &&
                        (get_valid_blocks(sbi, segno, true) >=
                        CAP_BLKS_PER_SEC(sbi) * valid_thresh_ratio / 100))
                return UINT_MAX;

        /* alloc_mode == LFS */
        if (p->gc_mode == GC_GREEDY)
                return get_valid_blocks(sbi, segno, true);
        else if (p->gc_mode == GC_CB)
                return get_cb_cost(sbi, segno);

        f2fs_bug_on(sbi, 1);
        return 0;
}

static unsigned int count_bits(const unsigned long *addr,
                                unsigned int offset, unsigned int len)
{
        unsigned int end = offset + len, sum = 0;

        while (offset < end) {
                if (test_bit(offset++, addr))
                        ++sum;
        }
        return sum;
}

static bool f2fs_check_victim_tree(struct f2fs_sb_info *sbi,
                                struct rb_root_cached *root)
{
#ifdef CONFIG_F2FS_CHECK_FS
        struct rb_node *cur = rb_first_cached(root), *next;
        struct victim_entry *cur_ve, *next_ve;

        while (cur) {
                next = rb_next(cur);
                if (!next)
                        return true;

                cur_ve = rb_entry(cur, struct victim_entry, rb_node);
                next_ve = rb_entry(next, struct victim_entry, rb_node);

                if (cur_ve->mtime > next_ve->mtime) {
                        f2fs_info(sbi, "broken victim_rbtree, "
                                "cur_mtime(%llu) next_mtime(%llu)",
                                cur_ve->mtime, next_ve->mtime);
                        return false;
                }
                cur = next;
        }
#endif
        return true;
}

static struct victim_entry *__lookup_victim_entry(struct f2fs_sb_info *sbi,
                                        unsigned long long mtime)
{
        struct atgc_management *am = &sbi->am;
        struct rb_node *node = am->root.rb_root.rb_node;
        struct victim_entry *ve = NULL;

        while (node) {
                ve = rb_entry(node, struct victim_entry, rb_node);

                if (mtime < ve->mtime)
                        node = node->rb_left;
                else
                        node = node->rb_right;
        }
        return ve;
}

static struct victim_entry *__create_victim_entry(struct f2fs_sb_info *sbi,
                unsigned long long mtime, unsigned int segno)
{
        struct atgc_management *am = &sbi->am;
        struct victim_entry *ve;

        ve =  f2fs_kmem_cache_alloc(victim_entry_slab, GFP_NOFS, true, NULL);

        ve->mtime = mtime;
        ve->segno = segno;

        list_add_tail(&ve->list, &am->victim_list);
        am->victim_count++;

        return ve;
}

static void __insert_victim_entry(struct f2fs_sb_info *sbi,
                                unsigned long long mtime, unsigned int segno)
{
        struct atgc_management *am = &sbi->am;
        struct rb_root_cached *root = &am->root;
        struct rb_node **p = &root->rb_root.rb_node;
        struct rb_node *parent = NULL;
        struct victim_entry *ve;
        bool left_most = true;

        /* look up rb tree to find parent node */
        while (*p) {
                parent = *p;
                ve = rb_entry(parent, struct victim_entry, rb_node);

                if (mtime < ve->mtime) {
                        p = &(*p)->rb_left;
                } else {
                        p = &(*p)->rb_right;
                        left_most = false;
                }
        }

        ve = __create_victim_entry(sbi, mtime, segno);

        rb_link_node(&ve->rb_node, parent, p);
        rb_insert_color_cached(&ve->rb_node, root, left_most);
}

static void add_victim_entry(struct f2fs_sb_info *sbi,
                                struct victim_sel_policy *p, unsigned int segno)
{
        struct sit_info *sit_i = SIT_I(sbi);
        unsigned long long mtime = 0;

        if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
                if (p->gc_mode == GC_AT &&
                        get_valid_blocks(sbi, segno, true) == 0)
                        return;
        }

        mtime = f2fs_get_section_mtime(sbi, segno);
        f2fs_bug_on(sbi, mtime == INVALID_MTIME);

        /* Handle if the system time has changed by the user */
        if (mtime < sit_i->min_mtime)
                sit_i->min_mtime = mtime;
        if (mtime > sit_i->max_mtime)
                sit_i->max_mtime = mtime;
        if (mtime < sit_i->dirty_min_mtime)
                sit_i->dirty_min_mtime = mtime;
        if (mtime > sit_i->dirty_max_mtime)
                sit_i->dirty_max_mtime = mtime;

        /* don't choose young section as candidate */
        if (sit_i->dirty_max_mtime - mtime < p->age_threshold)
                return;

        __insert_victim_entry(sbi, mtime, segno);
}

static void atgc_lookup_victim(struct f2fs_sb_info *sbi,
                                                struct victim_sel_policy *p)
{
        struct sit_info *sit_i = SIT_I(sbi);
        struct atgc_management *am = &sbi->am;
        struct rb_root_cached *root = &am->root;
        struct rb_node *node;
        struct victim_entry *ve;
        unsigned long long total_time;
        unsigned long long age, u, accu;
        unsigned long long max_mtime = sit_i->dirty_max_mtime;
        unsigned long long min_mtime = sit_i->dirty_min_mtime;
        unsigned int sec_blocks = CAP_BLKS_PER_SEC(sbi);
        unsigned int vblocks;
        unsigned int dirty_threshold = max(am->max_candidate_count,
                                        am->candidate_ratio *
                                        am->victim_count / 100);
        unsigned int age_weight = am->age_weight;
        unsigned int cost;
        unsigned int iter = 0;

        if (max_mtime < min_mtime)
                return;

        max_mtime += 1;
        total_time = max_mtime - min_mtime;

        accu = div64_u64(ULLONG_MAX, total_time);
        accu = min_t(unsigned long long, div_u64(accu, 100),
                                        DEFAULT_ACCURACY_CLASS);

        node = rb_first_cached(root);
next:
        ve = rb_entry_safe(node, struct victim_entry, rb_node);
        if (!ve)
                return;

        if (ve->mtime >= max_mtime || ve->mtime < min_mtime)
                goto skip;

        /* age = 10000 * x% * 60 */
        age = div64_u64(accu * (max_mtime - ve->mtime), total_time) *
                                                                age_weight;

        vblocks = get_valid_blocks(sbi, ve->segno, true);
        f2fs_bug_on(sbi, !vblocks || vblocks == sec_blocks);

        /* u = 10000 * x% * 40 */
        u = div64_u64(accu * (sec_blocks - vblocks), sec_blocks) *
                                                        (100 - age_weight);

        f2fs_bug_on(sbi, age + u >= UINT_MAX);

        cost = UINT_MAX - (age + u);
        iter++;

        if (cost < p->min_cost ||
                        (cost == p->min_cost && age > p->oldest_age)) {
                p->min_cost = cost;
                p->oldest_age = age;
                p->min_segno = ve->segno;
        }
skip:
        if (iter < dirty_threshold) {
                node = rb_next(node);
                goto next;
        }
}

/*
 * select candidates around source section in range of
 * [target - dirty_threshold, target + dirty_threshold]
 */
static void atssr_lookup_victim(struct f2fs_sb_info *sbi,
                                                struct victim_sel_policy *p)
{
        struct sit_info *sit_i = SIT_I(sbi);
        struct atgc_management *am = &sbi->am;
        struct victim_entry *ve;
        unsigned long long age;
        unsigned long long max_mtime = sit_i->dirty_max_mtime;
        unsigned long long min_mtime = sit_i->dirty_min_mtime;
        unsigned int vblocks;
        unsigned int dirty_threshold = max(am->max_candidate_count,
                                        am->candidate_ratio *
                                        am->victim_count / 100);
        unsigned int cost, iter;
        int stage = 0;

        if (max_mtime < min_mtime)
                return;
        max_mtime += 1;
next_stage:
        iter = 0;
        ve = __lookup_victim_entry(sbi, p->age);
next_node:
        if (!ve) {
                if (stage++ == 0)
                        goto next_stage;
                return;
        }

        if (ve->mtime >= max_mtime || ve->mtime < min_mtime)
                goto skip_node;

        age = max_mtime - ve->mtime;

        vblocks = get_seg_entry(sbi, ve->segno)->ckpt_valid_blocks;
        f2fs_bug_on(sbi, !vblocks);

        /* rare case */
        if (vblocks == BLKS_PER_SEG(sbi))
                goto skip_node;

        iter++;

        age = max_mtime - abs(p->age - age);
        cost = UINT_MAX - vblocks;

        if (cost < p->min_cost ||
                        (cost == p->min_cost && age > p->oldest_age)) {
                p->min_cost = cost;
                p->oldest_age = age;
                p->min_segno = ve->segno;
        }
skip_node:
        if (iter < dirty_threshold) {
                ve = rb_entry(stage == 0 ? rb_prev(&ve->rb_node) :
                                        rb_next(&ve->rb_node),
                                        struct victim_entry, rb_node);
                goto next_node;
        }

        if (stage++ == 0)
                goto next_stage;
}

static void lookup_victim_by_age(struct f2fs_sb_info *sbi,
                                                struct victim_sel_policy *p)
{
        f2fs_bug_on(sbi, !f2fs_check_victim_tree(sbi, &sbi->am.root));

        if (p->gc_mode == GC_AT)
                atgc_lookup_victim(sbi, p);
        else if (p->alloc_mode == AT_SSR)
                atssr_lookup_victim(sbi, p);
        else
                f2fs_bug_on(sbi, 1);
}

static void release_victim_entry(struct f2fs_sb_info *sbi)
{
        struct atgc_management *am = &sbi->am;
        struct victim_entry *ve, *tmp;

        list_for_each_entry_safe(ve, tmp, &am->victim_list, list) {
                list_del(&ve->list);
                kmem_cache_free(victim_entry_slab, ve);
                am->victim_count--;
        }

        am->root = RB_ROOT_CACHED;

        f2fs_bug_on(sbi, am->victim_count);
        f2fs_bug_on(sbi, !list_empty(&am->victim_list));
}

static bool f2fs_pin_section(struct f2fs_sb_info *sbi, unsigned int segno)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
        unsigned int secno = GET_SEC_FROM_SEG(sbi, segno);

        if (!dirty_i->enable_pin_section)
                return false;
        if (!test_and_set_bit(secno, dirty_i->pinned_secmap))
                dirty_i->pinned_secmap_cnt++;
        return true;
}

static bool f2fs_pinned_section_exists(struct dirty_seglist_info *dirty_i)
{
        return dirty_i->pinned_secmap_cnt;
}

static bool f2fs_section_is_pinned(struct dirty_seglist_info *dirty_i,
                                                unsigned int secno)
{
        return dirty_i->enable_pin_section &&
                f2fs_pinned_section_exists(dirty_i) &&
                test_bit(secno, dirty_i->pinned_secmap);
}

static void f2fs_unpin_all_sections(struct f2fs_sb_info *sbi, bool enable)
{
        unsigned int bitmap_size = f2fs_bitmap_size(MAIN_SECS(sbi));

        if (f2fs_pinned_section_exists(DIRTY_I(sbi))) {
                memset(DIRTY_I(sbi)->pinned_secmap, 0, bitmap_size);
                DIRTY_I(sbi)->pinned_secmap_cnt = 0;
        }
        DIRTY_I(sbi)->enable_pin_section = enable;
}

static int f2fs_gc_pinned_control(struct inode *inode, int gc_type,
                                                        unsigned int segno)
{
        if (!f2fs_is_pinned_file(inode))
                return 0;
        if (gc_type != FG_GC)
                return -EBUSY;
        if (!f2fs_pin_section(F2FS_I_SB(inode), segno))
                f2fs_pin_file_control(inode, true);
        return -EAGAIN;
}

/*
 * This function is called from two paths.
 * One is garbage collection and the other is SSR segment selection.
 * When it is called during GC, it just gets a victim segment
 * and it does not remove it from dirty seglist.
 * When it is called from SSR segment selection, it finds a segment
 * which has minimum valid blocks and removes it from dirty seglist.
 */
int f2fs_get_victim(struct f2fs_sb_info *sbi, unsigned int *result,
                        int gc_type, int type, char alloc_mode,
                        unsigned long long age, bool one_time)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
        struct sit_info *sm = SIT_I(sbi);
        struct victim_sel_policy p = {0};
        unsigned int secno, last_victim;
        unsigned int last_segment;
        unsigned int nsearched;
        unsigned int valid_thresh_ratio = 100;
        bool is_atgc;
        int ret = 0;

        mutex_lock(&dirty_i->seglist_lock);
        last_segment = MAIN_SECS(sbi) * SEGS_PER_SEC(sbi);

        p.alloc_mode = alloc_mode;
        p.age = age;
        p.age_threshold = sbi->am.age_threshold;
        if (one_time) {
                p.one_time_gc = one_time;
                if (has_enough_free_secs(sbi, 0, NR_PERSISTENT_LOG))
                        valid_thresh_ratio = sbi->gc_thread->valid_thresh_ratio;
        }

retry:
        select_policy(sbi, gc_type, type, &p);
        p.min_segno = NULL_SEGNO;
        p.oldest_age = 0;
        p.min_cost = get_max_cost(sbi, &p);

        is_atgc = (p.gc_mode == GC_AT || p.alloc_mode == AT_SSR);
        nsearched = 0;

        if (is_atgc)
                SIT_I(sbi)->dirty_min_mtime = ULLONG_MAX;

        if (*result != NULL_SEGNO) {
                if (!get_valid_blocks(sbi, *result, false)) {
                        ret = -ENODATA;
                        goto out;
                }

                if (sec_usage_check(sbi, GET_SEC_FROM_SEG(sbi, *result))) {
                        ret = -EBUSY;
                        goto out;
                }
                if (gc_type == FG_GC)
                        clear_bit(GET_SEC_FROM_SEG(sbi, *result), dirty_i->victim_secmap);
                p.min_segno = *result;
                goto got_result;
        }

        ret = -ENODATA;
        if (p.max_search == 0)
                goto out;

        if (__is_large_section(sbi) && p.alloc_mode == LFS) {
                if (sbi->next_victim_seg[BG_GC] != NULL_SEGNO) {
                        p.min_segno = sbi->next_victim_seg[BG_GC];
                        *result = p.min_segno;
                        sbi->next_victim_seg[BG_GC] = NULL_SEGNO;
                        goto got_result;
                }
                if (gc_type == FG_GC &&
                                sbi->next_victim_seg[FG_GC] != NULL_SEGNO) {
                        p.min_segno = sbi->next_victim_seg[FG_GC];
                        *result = p.min_segno;
                        sbi->next_victim_seg[FG_GC] = NULL_SEGNO;
                        goto got_result;
                }
        }

        last_victim = sm->last_victim[p.gc_mode];
        if (p.alloc_mode == LFS && gc_type == FG_GC) {
                p.min_segno = check_bg_victims(sbi);
                if (p.min_segno != NULL_SEGNO)
                        goto got_it;
        }

        while (1) {
                unsigned long cost, *dirty_bitmap;
                unsigned int unit_no, segno;

                dirty_bitmap = p.dirty_bitmap;
                unit_no = find_next_bit(dirty_bitmap,
                                last_segment / p.ofs_unit,
                                p.offset / p.ofs_unit);
                segno = unit_no * p.ofs_unit;
                if (segno >= last_segment) {
                        if (sm->last_victim[p.gc_mode]) {
                                last_segment =
                                        sm->last_victim[p.gc_mode];
                                sm->last_victim[p.gc_mode] = 0;
                                p.offset = 0;
                                continue;
                        }
                        break;
                }

                p.offset = segno + p.ofs_unit;
                nsearched++;

#ifdef CONFIG_F2FS_CHECK_FS
                /*
                 * skip selecting the invalid segno (that is failed due to block
                 * validity check failure during GC) to avoid endless GC loop in
                 * such cases.
                 */
                if (test_bit(segno, sm->invalid_segmap))
                        goto next;
#endif

                secno = GET_SEC_FROM_SEG(sbi, segno);

                if (sec_usage_check(sbi, secno))
                        goto next;

                /* Don't touch checkpointed data */
                if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED))) {
                        if (p.alloc_mode == LFS) {
                                /*
                                 * LFS is set to find source section during GC.
                                 * The victim should have no checkpointed data.
                                 */
                                if (get_ckpt_valid_blocks(sbi, segno, true))
                                        goto next;
                        } else {
                                /*
                                 * SSR | AT_SSR are set to find target segment
                                 * for writes which can be full by checkpointed
                                 * and newly written blocks.
                                 */
                                if (!f2fs_segment_has_free_slot(sbi, segno))
                                        goto next;
                        }
                }

                if (gc_type == BG_GC && test_bit(secno, dirty_i->victim_secmap))
                        goto next;

                if (gc_type == FG_GC && f2fs_section_is_pinned(dirty_i, secno))
                        goto next;

                if (is_atgc) {
                        add_victim_entry(sbi, &p, segno);
                        goto next;
                }

                cost = get_gc_cost(sbi, segno, &p, valid_thresh_ratio);

                if (p.min_cost > cost) {
                        p.min_segno = segno;
                        p.min_cost = cost;
                }
next:
                if (nsearched >= p.max_search) {
                        if (!sm->last_victim[p.gc_mode] && segno <= last_victim)
                                sm->last_victim[p.gc_mode] =
                                        last_victim + p.ofs_unit;
                        else
                                sm->last_victim[p.gc_mode] = segno + p.ofs_unit;
                        sm->last_victim[p.gc_mode] %=
                                (MAIN_SECS(sbi) * SEGS_PER_SEC(sbi));
                        break;
                }
        }

        /* get victim for GC_AT/AT_SSR */
        if (is_atgc) {
                lookup_victim_by_age(sbi, &p);
                release_victim_entry(sbi);
        }

        if (is_atgc && p.min_segno == NULL_SEGNO &&
                        sm->elapsed_time < p.age_threshold) {
                p.age_threshold = 0;
                goto retry;
        }

        if (p.min_segno != NULL_SEGNO) {
got_it:
                *result = (p.min_segno / p.ofs_unit) * p.ofs_unit;
got_result:
                if (p.alloc_mode == LFS) {
                        secno = GET_SEC_FROM_SEG(sbi, p.min_segno);
                        if (gc_type == FG_GC)
                                sbi->cur_victim_sec = secno;
                        else
                                set_bit(secno, dirty_i->victim_secmap);
                }
                ret = 0;

        }
out:
        if (p.min_segno != NULL_SEGNO)
                trace_f2fs_get_victim(sbi->sb, type, gc_type, &p,
                                sbi->cur_victim_sec,
                                prefree_segments(sbi), free_segments(sbi));
        mutex_unlock(&dirty_i->seglist_lock);

        return ret;
}

static struct inode *find_gc_inode(struct gc_inode_list *gc_list, nid_t ino)
{
        struct inode_entry *ie;

        ie = radix_tree_lookup(&gc_list->iroot, ino);
        if (ie)
                return ie->inode;
        return NULL;
}

static void add_gc_inode(struct gc_inode_list *gc_list, struct inode *inode)
{
        struct inode_entry *new_ie;

        if (inode == find_gc_inode(gc_list, inode->i_ino)) {
                iput(inode);
                return;
        }
        new_ie = f2fs_kmem_cache_alloc(f2fs_inode_entry_slab,
                                        GFP_NOFS, true, NULL);
        new_ie->inode = inode;

        f2fs_radix_tree_insert(&gc_list->iroot, inode->i_ino, new_ie);
        list_add_tail(&new_ie->list, &gc_list->ilist);
}

static void put_gc_inode(struct gc_inode_list *gc_list)
{
        struct inode_entry *ie, *next_ie;

        list_for_each_entry_safe(ie, next_ie, &gc_list->ilist, list) {
                radix_tree_delete(&gc_list->iroot, ie->inode->i_ino);
                iput(ie->inode);
                list_del(&ie->list);
                kmem_cache_free(f2fs_inode_entry_slab, ie);
        }
}

static int check_valid_map(struct f2fs_sb_info *sbi,
                                unsigned int segno, int offset)
{
        struct sit_info *sit_i = SIT_I(sbi);
        struct seg_entry *sentry;
        int ret;

        down_read(&sit_i->sentry_lock);
        sentry = get_seg_entry(sbi, segno);
        ret = f2fs_test_bit(offset, sentry->cur_valid_map);
        up_read(&sit_i->sentry_lock);
        return ret;
}

/*
 * This function compares node address got in summary with that in NAT.
 * On validity, copy that node with cold status, otherwise (invalid node)
 * ignore that.
 */
static int gc_node_segment(struct f2fs_sb_info *sbi,
                struct f2fs_summary *sum, unsigned int segno, int gc_type,
                struct blk_plug *plug)
{
        struct f2fs_summary *entry;
        block_t start_addr;
        int off;
        int phase = 0;
        bool fggc = (gc_type == FG_GC);
        int submitted = 0;
        unsigned int usable_blks_in_seg = f2fs_usable_blks_in_seg(sbi, segno);

        start_addr = START_BLOCK(sbi, segno);

next_step:
        entry = sum;

        if (fggc && phase == 2)
                atomic_inc(&sbi->wb_sync_req[NODE]);

        for (off = 0; off < usable_blks_in_seg; off++, entry++) {
                nid_t nid = le32_to_cpu(entry->nid);
                struct folio *node_folio;
                struct node_info ni;
                int err;

                /* stop BG_GC if there is not enough free sections. */
                if (gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0))
                        return submitted;

                if (check_valid_map(sbi, segno, off) == 0)
                        continue;

                if (phase == 0) {
                        f2fs_ra_meta_pages(sbi, NAT_BLOCK_OFFSET(nid), 1,
                                                        META_NAT, true);
                        continue;
                }

                if (phase == 1) {
                        f2fs_ra_node_page(sbi, nid);
                        continue;
                }

                /* phase == 2 */
                node_folio = f2fs_get_node_folio(sbi, nid, NODE_TYPE_REGULAR);
                if (IS_ERR(node_folio))
                        continue;

                /* block may become invalid during f2fs_get_node_folio */
                if (check_valid_map(sbi, segno, off) == 0) {
                        f2fs_folio_put(node_folio, true);
                        continue;
                }

                if (f2fs_get_node_info(sbi, nid, &ni, false)) {
                        f2fs_folio_put(node_folio, true);
                        continue;
                }

                if (ni.blk_addr != start_addr + off) {
                        f2fs_folio_put(node_folio, true);
                        continue;
                }

                err = f2fs_move_node_folio(node_folio, gc_type);
                if (!err && gc_type == FG_GC)
                        submitted++;
                stat_inc_node_blk_count(sbi, 1, gc_type);
        }

        if (++phase < 3) {
                blk_finish_plug(plug);
                blk_start_plug(plug);
                goto next_step;
        }

        if (fggc)
                atomic_dec(&sbi->wb_sync_req[NODE]);
        return submitted;
}

/*
 * Calculate start block index indicating the given node offset.
 * Be careful, caller should give this node offset only indicating direct node
 * blocks. If any node offsets, which point the other types of node blocks such
 * as indirect or double indirect node blocks, are given, it must be a caller's
 * bug.
 */
block_t f2fs_start_bidx_of_node(unsigned int node_ofs, struct inode *inode)
{
        unsigned int indirect_blks = 2 * NIDS_PER_BLOCK + 4;
        unsigned int bidx;

        if (node_ofs == 0)
                return 0;

        if (node_ofs <= 2) {
                bidx = node_ofs - 1;
        } else if (node_ofs <= indirect_blks) {
                int dec = (node_ofs - 4) / (NIDS_PER_BLOCK + 1);

                bidx = node_ofs - 2 - dec;
        } else {
                int dec = (node_ofs - indirect_blks - 3) / (NIDS_PER_BLOCK + 1);

                bidx = node_ofs - 5 - dec;
        }
        return bidx * ADDRS_PER_BLOCK(inode) + ADDRS_PER_INODE(inode);
}

static bool is_alive(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
                struct node_info *dni, block_t blkaddr, unsigned int *nofs)
{
        struct folio *node_folio;
        nid_t nid;
        unsigned int ofs_in_node, max_addrs, base;
        block_t source_blkaddr;

        nid = le32_to_cpu(sum->nid);
        ofs_in_node = le16_to_cpu(sum->ofs_in_node);

        node_folio = f2fs_get_node_folio(sbi, nid, NODE_TYPE_REGULAR);
        if (IS_ERR(node_folio))
                return false;

        if (f2fs_get_node_info(sbi, nid, dni, false)) {
                f2fs_folio_put(node_folio, true);
                return false;
        }

        if (sum->version != dni->version) {
                f2fs_warn(sbi, "%s: valid data with mismatched node version.",
                          __func__);
                set_sbi_flag(sbi, SBI_NEED_FSCK);
        }

        if (f2fs_check_nid_range(sbi, dni->ino)) {
                f2fs_folio_put(node_folio, true);
                return false;
        }

        if (IS_INODE(node_folio)) {
                base = offset_in_addr(F2FS_INODE(node_folio));
                max_addrs = DEF_ADDRS_PER_INODE;
        } else {
                base = 0;
                max_addrs = DEF_ADDRS_PER_BLOCK;
        }

        if (base + ofs_in_node >= max_addrs) {
                f2fs_err(sbi, "Inconsistent blkaddr offset: base:%u, ofs_in_node:%u, max:%u, ino:%u, nid:%u",
                        base, ofs_in_node, max_addrs, dni->ino, dni->nid);
                f2fs_folio_put(node_folio, true);
                return false;
        }

        *nofs = ofs_of_node(node_folio);
        source_blkaddr = data_blkaddr(NULL, node_folio, ofs_in_node);
        f2fs_folio_put(node_folio, true);

        if (source_blkaddr != blkaddr) {
#ifdef CONFIG_F2FS_CHECK_FS
                unsigned int segno = GET_SEGNO(sbi, blkaddr);
                unsigned long offset = GET_BLKOFF_FROM_SEG0(sbi, blkaddr);

                if (unlikely(check_valid_map(sbi, segno, offset))) {
                        if (!test_and_set_bit(segno, SIT_I(sbi)->invalid_segmap)) {
                                f2fs_err(sbi, "mismatched blkaddr %u (source_blkaddr %u) in seg %u",
                                         blkaddr, source_blkaddr, segno);
                                set_sbi_flag(sbi, SBI_NEED_FSCK);
                        }
                }
#endif
                return false;
        }
        return true;
}

static int ra_data_block(struct inode *inode, pgoff_t index)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct address_space *mapping = f2fs_is_cow_file(inode) ?
                                F2FS_I(inode)->atomic_inode->i_mapping : inode->i_mapping;
        struct dnode_of_data dn;
        struct folio *folio, *efolio;
        struct f2fs_io_info fio = {
                .sbi = sbi,
                .ino = inode->i_ino,
                .type = DATA,
                .temp = COLD,
                .op = REQ_OP_READ,
                .op_flags = 0,
                .encrypted_page = NULL,
                .in_list = 0,
        };
        int err;

        folio = f2fs_grab_cache_folio(mapping, index, true);
        if (IS_ERR(folio))
                return PTR_ERR(folio);

        if (f2fs_lookup_read_extent_cache_block(inode, index,
                                                &dn.data_blkaddr)) {
                if (unlikely(!f2fs_is_valid_blkaddr(sbi, dn.data_blkaddr,
                                                DATA_GENERIC_ENHANCE_READ))) {
                        err = -EFSCORRUPTED;
                        goto put_folio;
                }
                goto got_it;
        }

        set_new_dnode(&dn, inode, NULL, NULL, 0);
        err = f2fs_get_dnode_of_data(&dn, index, LOOKUP_NODE);
        if (err)
                goto put_folio;
        f2fs_put_dnode(&dn);

        if (!__is_valid_data_blkaddr(dn.data_blkaddr)) {
                err = -ENOENT;
                goto put_folio;
        }
        if (unlikely(!f2fs_is_valid_blkaddr(sbi, dn.data_blkaddr,
                                                DATA_GENERIC_ENHANCE))) {
                err = -EFSCORRUPTED;
                goto put_folio;
        }
got_it:
        /* read folio */
        fio.folio = folio;
        fio.new_blkaddr = fio.old_blkaddr = dn.data_blkaddr;

        /*
         * don't cache encrypted data into meta inode until previous dirty
         * data were writebacked to avoid racing between GC and flush.
         */
        f2fs_folio_wait_writeback(folio, DATA, true, true);

        f2fs_wait_on_block_writeback(inode, dn.data_blkaddr);

        efolio = f2fs_filemap_get_folio(META_MAPPING(sbi), dn.data_blkaddr,
                                        FGP_LOCK | FGP_CREAT, GFP_NOFS);
        if (IS_ERR(efolio)) {
                err = PTR_ERR(efolio);
                goto put_folio;
        }

        fio.encrypted_page = &efolio->page;

        err = f2fs_submit_page_bio(&fio);
        if (err)
                goto put_encrypted_page;
        f2fs_put_page(fio.encrypted_page, false);
        f2fs_folio_put(folio, true);

        f2fs_update_iostat(sbi, inode, FS_DATA_READ_IO, F2FS_BLKSIZE);
        f2fs_update_iostat(sbi, NULL, FS_GDATA_READ_IO, F2FS_BLKSIZE);

        return 0;
put_encrypted_page:
        f2fs_put_page(fio.encrypted_page, true);
put_folio:
        f2fs_folio_put(folio, true);
        return err;
}

/*
 * Move data block via META_MAPPING while keeping locked data page.
 * This can be used to move blocks, aka LBAs, directly on disk.
 */
static int move_data_block(struct inode *inode, block_t bidx,
                                int gc_type, unsigned int segno, int off)
{
        struct address_space *mapping = f2fs_is_cow_file(inode) ?
                                F2FS_I(inode)->atomic_inode->i_mapping : inode->i_mapping;
        struct f2fs_io_info fio = {
                .sbi = F2FS_I_SB(inode),
                .ino = inode->i_ino,
                .type = DATA,
                .temp = COLD,
                .op = REQ_OP_READ,
                .op_flags = 0,
                .encrypted_page = NULL,
                .in_list = 0,
        };
        struct dnode_of_data dn;
        struct f2fs_summary sum;
        struct node_info ni;
        struct folio *folio, *mfolio, *efolio;
        block_t newaddr;
        int err = 0;
        bool lfs_mode = f2fs_lfs_mode(fio.sbi);
        int type = fio.sbi->am.atgc_enabled && (gc_type == BG_GC) &&
                                (fio.sbi->gc_mode != GC_URGENT_HIGH) ?
                                CURSEG_ALL_DATA_ATGC : CURSEG_COLD_DATA;

        /* do not read out */
        folio = f2fs_grab_cache_folio(mapping, bidx, false);
        if (IS_ERR(folio))
                return PTR_ERR(folio);

        if (!check_valid_map(F2FS_I_SB(inode), segno, off)) {
                err = -ENOENT;
                goto out;
        }

        err = f2fs_gc_pinned_control(inode, gc_type, segno);
        if (err)
                goto out;

        set_new_dnode(&dn, inode, NULL, NULL, 0);
        err = f2fs_get_dnode_of_data(&dn, bidx, LOOKUP_NODE);
        if (err)
                goto out;

        if (unlikely(dn.data_blkaddr == NULL_ADDR)) {
                folio_clear_uptodate(folio);
                err = -ENOENT;
                goto put_out;
        }

        /*
         * don't cache encrypted data into meta inode until previous dirty
         * data were writebacked to avoid racing between GC and flush.
         */
        f2fs_folio_wait_writeback(folio, DATA, true, true);

        f2fs_wait_on_block_writeback(inode, dn.data_blkaddr);

        err = f2fs_get_node_info(fio.sbi, dn.nid, &ni, false);
        if (err)
                goto put_out;

        /* read page */
        fio.folio = folio;
        fio.new_blkaddr = fio.old_blkaddr = dn.data_blkaddr;

        if (lfs_mode)
                f2fs_down_write(&fio.sbi->io_order_lock);

        mfolio = f2fs_grab_cache_folio(META_MAPPING(fio.sbi),
                                        fio.old_blkaddr, false);
        if (IS_ERR(mfolio)) {
                err = PTR_ERR(mfolio);
                goto up_out;
        }

        fio.encrypted_page = folio_file_page(mfolio, fio.old_blkaddr);

        /* read source block in mfolio */
        if (!folio_test_uptodate(mfolio)) {
                err = f2fs_submit_page_bio(&fio);
                if (err) {
                        f2fs_folio_put(mfolio, true);
                        goto up_out;
                }

                f2fs_update_iostat(fio.sbi, inode, FS_DATA_READ_IO,
                                                        F2FS_BLKSIZE);
                f2fs_update_iostat(fio.sbi, NULL, FS_GDATA_READ_IO,
                                                        F2FS_BLKSIZE);

                folio_lock(mfolio);
                if (unlikely(!is_meta_folio(mfolio) ||
                             !folio_test_uptodate(mfolio))) {
                        err = -EIO;
                        f2fs_folio_put(mfolio, true);
                        goto up_out;
                }
        }

        set_summary(&sum, dn.nid, dn.ofs_in_node, ni.version);

        /* allocate block address */
        err = f2fs_allocate_data_block(fio.sbi, NULL, fio.old_blkaddr, &newaddr,
                                &sum, type, NULL);
        if (err) {
                f2fs_folio_put(mfolio, true);
                /* filesystem should shutdown, no need to recovery block */
                goto up_out;
        }

        efolio = f2fs_filemap_get_folio(META_MAPPING(fio.sbi), newaddr,
                                        FGP_LOCK | FGP_CREAT, GFP_NOFS);
        if (IS_ERR(efolio)) {
                err = PTR_ERR(efolio);
                f2fs_folio_put(mfolio, true);
                goto recover_block;
        }

        fio.encrypted_page = &efolio->page;

        /* write target block */
        f2fs_wait_on_page_writeback(fio.encrypted_page, DATA, true, true);
        memcpy(page_address(fio.encrypted_page),
                                folio_address(mfolio), PAGE_SIZE);
        f2fs_folio_put(mfolio, true);

        f2fs_invalidate_internal_cache(fio.sbi, fio.old_blkaddr, 1);

        set_page_dirty(fio.encrypted_page);
        if (clear_page_dirty_for_io(fio.encrypted_page))
                dec_page_count(fio.sbi, F2FS_DIRTY_META);

        set_page_writeback(fio.encrypted_page);

        fio.op = REQ_OP_WRITE;
        fio.op_flags = REQ_SYNC;
        fio.new_blkaddr = newaddr;
        f2fs_submit_page_write(&fio);

        f2fs_update_iostat(fio.sbi, NULL, FS_GC_DATA_IO, F2FS_BLKSIZE);

        f2fs_update_data_blkaddr(&dn, newaddr);
        set_inode_flag(inode, FI_APPEND_WRITE);

        f2fs_put_page(fio.encrypted_page, true);
recover_block:
        if (err)
                f2fs_do_replace_block(fio.sbi, &sum, newaddr, fio.old_blkaddr,
                                                        true, true, true);
up_out:
        if (lfs_mode)
                f2fs_up_write(&fio.sbi->io_order_lock);
put_out:
        f2fs_put_dnode(&dn);
out:
        if (!folio_test_uptodate(folio))
                __folio_set_dropbehind(folio);
        folio_unlock(folio);
        folio_end_dropbehind(folio);
        folio_put(folio);
        return err;
}

static int move_data_page(struct inode *inode, block_t bidx, int gc_type,
                                                unsigned int segno, int off)
{
        struct folio *folio;
        int err = 0;

        folio = f2fs_get_lock_data_folio(inode, bidx, true);
        if (IS_ERR(folio))
                return PTR_ERR(folio);

        if (!check_valid_map(F2FS_I_SB(inode), segno, off)) {
                err = -ENOENT;
                goto out;
        }

        err = f2fs_gc_pinned_control(inode, gc_type, segno);
        if (err)
                goto out;

        if (gc_type == BG_GC) {
                if (folio_test_writeback(folio)) {
                        err = -EAGAIN;
                        goto out;
                }
                folio_mark_dirty(folio);
                folio_set_f2fs_gcing(folio);
        } else {
                struct f2fs_io_info fio = {
                        .sbi = F2FS_I_SB(inode),
                        .ino = inode->i_ino,
                        .type = DATA,
                        .temp = COLD,
                        .op = REQ_OP_WRITE,
                        .op_flags = REQ_SYNC,
                        .old_blkaddr = NULL_ADDR,
                        .folio = folio,
                        .encrypted_page = NULL,
                        .need_lock = LOCK_REQ,
                        .io_type = FS_GC_DATA_IO,
                };
                bool is_dirty = folio_test_dirty(folio);

retry:
                f2fs_folio_wait_writeback(folio, DATA, true, true);

                folio_mark_dirty(folio);
                if (folio_clear_dirty_for_io(folio)) {
                        inode_dec_dirty_pages(inode);
                        f2fs_remove_dirty_inode(inode);
                }

                folio_set_f2fs_gcing(folio);

                err = f2fs_do_write_data_page(&fio);
                if (err) {
                        folio_clear_f2fs_gcing(folio);
                        if (err == -ENOMEM) {
                                memalloc_retry_wait(GFP_NOFS);
                                goto retry;
                        }
                        if (is_dirty)
                                folio_mark_dirty(folio);
                }
        }
out:
        f2fs_folio_put(folio, true);
        return err;
}

/*
 * This function tries to get parent node of victim data block, and identifies
 * data block validity. If the block is valid, copy that with cold status and
 * modify parent node.
 * If the parent node is not valid or the data block address is different,
 * the victim data block is ignored.
 */
static int gc_data_segment(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
                struct gc_inode_list *gc_list, unsigned int segno, int gc_type,
                bool force_migrate, struct blk_plug *plug)
{
        struct super_block *sb = sbi->sb;
        struct f2fs_summary *entry;
        block_t start_addr;
        int off;
        int phase = 0;
        int submitted = 0;
        unsigned int usable_blks_in_seg = f2fs_usable_blks_in_seg(sbi, segno);

        start_addr = START_BLOCK(sbi, segno);

next_step:
        entry = sum;

        for (off = 0; off < usable_blks_in_seg; off++, entry++) {
                struct inode *inode;
                struct node_info dni; /* dnode info for the data */
                unsigned int ofs_in_node, nofs;
                block_t start_bidx;
                nid_t nid = le32_to_cpu(entry->nid);

                /*
                 * stop BG_GC if there is not enough free sections.
                 * Or, stop GC if the segment becomes fully valid caused by
                 * race condition along with SSR block allocation.
                 */
                if ((gc_type == BG_GC && has_not_enough_free_secs(sbi, 0, 0)) ||
                        (!force_migrate && get_valid_blocks(sbi, segno, true) ==
                                                        CAP_BLKS_PER_SEC(sbi)))
                        return submitted;

                if (check_valid_map(sbi, segno, off) == 0)
                        continue;

                if (phase == 0) {
                        f2fs_ra_meta_pages(sbi, NAT_BLOCK_OFFSET(nid), 1,
                                                        META_NAT, true);
                        continue;
                }

                if (phase == 1) {
                        f2fs_ra_node_page(sbi, nid);
                        continue;
                }

                /* Get an inode by ino with checking validity */
                if (!is_alive(sbi, entry, &dni, start_addr + off, &nofs))
                        continue;

                if (phase == 2) {
                        f2fs_ra_node_page(sbi, dni.ino);
                        continue;
                }

                ofs_in_node = le16_to_cpu(entry->ofs_in_node);

                if (phase == 3) {
                        struct folio *data_folio;
                        int err;

                        inode = f2fs_iget(sb, dni.ino);
                        if (IS_ERR(inode))
                                continue;

                        if (is_bad_inode(inode) ||
                                        special_file(inode->i_mode)) {
                                iput(inode);
                                continue;
                        }

                        if (f2fs_has_inline_data(inode)) {
                                iput(inode);
                                set_sbi_flag(sbi, SBI_NEED_FSCK);
                                f2fs_err_ratelimited(sbi,
                                        "inode %lx has both inline_data flag and "
                                        "data block, nid=%u, ofs_in_node=%u",
                                        inode->i_ino, dni.nid, ofs_in_node);
                                continue;
                        }

                        err = f2fs_gc_pinned_control(inode, gc_type, segno);
                        if (err == -EAGAIN) {
                                iput(inode);
                                return submitted;
                        }

                        if (!f2fs_down_write_trylock(
                                &F2FS_I(inode)->i_gc_rwsem[WRITE])) {
                                iput(inode);
                                sbi->skipped_gc_rwsem++;
                                continue;
                        }

                        start_bidx = f2fs_start_bidx_of_node(nofs, inode) +
                                                                ofs_in_node;

                        if (f2fs_meta_inode_gc_required(inode)) {
                                int err = ra_data_block(inode, start_bidx);

                                f2fs_up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
                                if (err) {
                                        iput(inode);
                                        continue;
                                }
                                add_gc_inode(gc_list, inode);
                                continue;
                        }

                        data_folio = f2fs_get_read_data_folio(inode, start_bidx,
                                                        REQ_RAHEAD, true, NULL);
                        f2fs_up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
                        if (IS_ERR(data_folio)) {
                                iput(inode);
                                continue;
                        }

                        f2fs_folio_put(data_folio, false);
                        add_gc_inode(gc_list, inode);
                        continue;
                }

                /* phase 4 */
                inode = find_gc_inode(gc_list, dni.ino);
                if (inode) {
                        struct f2fs_inode_info *fi = F2FS_I(inode);
                        bool locked = false;
                        int err;

                        if (S_ISREG(inode->i_mode)) {
                                if (!f2fs_down_write_trylock(&fi->i_gc_rwsem[WRITE])) {
                                        sbi->skipped_gc_rwsem++;
                                        continue;
                                }
                                if (!f2fs_down_write_trylock(
                                                &fi->i_gc_rwsem[READ])) {
                                        sbi->skipped_gc_rwsem++;
                                        f2fs_up_write(&fi->i_gc_rwsem[WRITE]);
                                        continue;
                                }
                                locked = true;

                                /* wait for all inflight aio data */
                                inode_dio_wait(inode);
                        }

                        start_bidx = f2fs_start_bidx_of_node(nofs, inode)
                                                                + ofs_in_node;
                        if (f2fs_meta_inode_gc_required(inode))
                                err = move_data_block(inode, start_bidx,
                                                        gc_type, segno, off);
                        else
                                err = move_data_page(inode, start_bidx, gc_type,
                                                                segno, off);

                        if (!err && (gc_type == FG_GC ||
                                        f2fs_meta_inode_gc_required(inode)))
                                submitted++;

                        if (locked) {
                                f2fs_up_write(&fi->i_gc_rwsem[READ]);
                                f2fs_up_write(&fi->i_gc_rwsem[WRITE]);
                        }

                        stat_inc_data_blk_count(sbi, 1, gc_type);
                }
        }

        if (++phase < 5) {
                blk_finish_plug(plug);
                blk_start_plug(plug);
                goto next_step;
        }

        return submitted;
}

static int __get_victim(struct f2fs_sb_info *sbi, unsigned int *victim,
                        int gc_type, bool one_time)
{
        struct sit_info *sit_i = SIT_I(sbi);
        int ret;

        down_write(&sit_i->sentry_lock);
        ret = f2fs_get_victim(sbi, victim, gc_type, NO_CHECK_TYPE,
                        LFS, 0, one_time);
        up_write(&sit_i->sentry_lock);
        return ret;
}

static int do_garbage_collect(struct f2fs_sb_info *sbi,
                                unsigned int start_segno,
                                struct gc_inode_list *gc_list, int gc_type,
                                bool force_migrate, bool one_time)
{
        struct blk_plug plug;
        unsigned int segno = start_segno;
        unsigned int end_segno = start_segno + SEGS_PER_SEC(sbi);
        unsigned int sec_end_segno;
        int seg_freed = 0, migrated = 0;
        unsigned char type = IS_DATASEG(get_seg_entry(sbi, segno)->type) ?
                                                SUM_TYPE_DATA : SUM_TYPE_NODE;
        unsigned char data_type = (type == SUM_TYPE_DATA) ? DATA : NODE;
        int submitted = 0, sum_blk_cnt;

        if (__is_large_section(sbi)) {
                sec_end_segno = rounddown(end_segno, SEGS_PER_SEC(sbi));

                /*
                 * zone-capacity can be less than zone-size in zoned devices,
                 * resulting in less than expected usable segments in the zone,
                 * calculate the end segno in the zone which can be garbage
                 * collected
                 */
                if (f2fs_sb_has_blkzoned(sbi))
                        sec_end_segno -= SEGS_PER_SEC(sbi) -
                                        f2fs_usable_segs_in_sec(sbi);

                if (gc_type == BG_GC || one_time) {
                        unsigned int window_granularity =
                                sbi->migration_window_granularity;

                        if (f2fs_sb_has_blkzoned(sbi) &&
                                        !has_enough_free_blocks(sbi,
                                        sbi->gc_thread->boost_zoned_gc_percent))
                                window_granularity *=
                                        sbi->gc_thread->boost_gc_multiple;

                        end_segno = start_segno + window_granularity;
                }

                if (end_segno > sec_end_segno)
                        end_segno = sec_end_segno;
        }

        sanity_check_seg_type(sbi, get_seg_entry(sbi, segno)->type);

        segno = rounddown(segno, sbi->sums_per_block);
        sum_blk_cnt = DIV_ROUND_UP(end_segno - segno, sbi->sums_per_block);
        /* readahead multi ssa blocks those have contiguous address */
        if (__is_large_section(sbi))
                f2fs_ra_meta_pages(sbi, GET_SUM_BLOCK(sbi, segno),
                                        sum_blk_cnt, META_SSA, true);

        /* reference all summary page */
        while (segno < end_segno) {
                struct folio *sum_folio = f2fs_get_sum_folio(sbi, segno);

                segno += sbi->sums_per_block;
                if (IS_ERR(sum_folio)) {
                        int err = PTR_ERR(sum_folio);

                        end_segno = segno - sbi->sums_per_block;
                        segno = rounddown(start_segno, sbi->sums_per_block);
                        while (segno < end_segno) {
                                sum_folio = filemap_get_folio(META_MAPPING(sbi),
                                                GET_SUM_BLOCK(sbi, segno));
                                folio_put_refs(sum_folio, 2);
                                segno += sbi->sums_per_block;
                        }
                        return err;
                }
                folio_unlock(sum_folio);
        }

        blk_start_plug(&plug);

        segno = start_segno;
        while (segno < end_segno) {
                unsigned int cur_segno;

                /* find segment summary of victim */
                struct folio *sum_folio = filemap_get_folio(META_MAPPING(sbi),
                                        GET_SUM_BLOCK(sbi, segno));
                unsigned int block_end_segno = rounddown(segno, sbi->sums_per_block)
                                        + sbi->sums_per_block;

                if (block_end_segno > end_segno)
                        block_end_segno = end_segno;

                if (is_cursec(sbi, GET_SEC_FROM_SEG(sbi, segno))) {
                        f2fs_err(sbi, "%s: segment %u is used by log",
                                                        __func__, segno);
                        f2fs_bug_on(sbi, 1);
                        goto next_block;
                }

                if (!folio_test_uptodate(sum_folio) ||
                    unlikely(f2fs_cp_error(sbi)))
                        goto next_block;

                for (cur_segno = segno; cur_segno < block_end_segno;
                                cur_segno++) {
                        struct f2fs_summary_block *sum;

                        if (get_valid_blocks(sbi, cur_segno, false) == 0)
                                goto freed;
                        if (gc_type == BG_GC && __is_large_section(sbi) &&
                                        migrated >= sbi->migration_granularity)
                                continue;

                        sum = SUM_BLK_PAGE_ADDR(sbi, sum_folio, cur_segno);
                        if (type != GET_SUM_TYPE(sum_footer(sbi, sum))) {
                                f2fs_err(sbi, "Inconsistent segment (%u) type "
                                                "[%d, %d] in SSA and SIT",
                                                cur_segno, type,
                                                GET_SUM_TYPE(
                                                sum_footer(sbi, sum)));
                                f2fs_stop_checkpoint(sbi, false,
                                                STOP_CP_REASON_CORRUPTED_SUMMARY);
                                continue;
                        }

                        /*
                         * this is to avoid deadlock:
                         *  - lock_page(sum_page)     - f2fs_replace_block
                         *   - check_valid_map()        - down_write(sentry_lock)
                         *    - down_read(sentry_lock) - change_curseg()
                         *                               - lock_page(sum_page)
                         */
                        if (type == SUM_TYPE_NODE)
                                submitted += gc_node_segment(sbi, sum->entries,
                                                cur_segno, gc_type, &plug);
                        else
                                submitted += gc_data_segment(sbi, sum->entries,
                                                gc_list, cur_segno,
                                                gc_type, force_migrate, &plug);

                        stat_inc_gc_seg_count(sbi, data_type, gc_type);
                        sbi->gc_reclaimed_segs[sbi->gc_mode]++;
                        migrated++;

freed:
                        if (gc_type == FG_GC &&
                                        get_valid_blocks(sbi, cur_segno, false) == 0)
                                seg_freed++;

                        if (__is_large_section(sbi))
                                sbi->next_victim_seg[gc_type] =
                                        (cur_segno + 1 < sec_end_segno) ?
                                        cur_segno + 1 : NULL_SEGNO;
                }
next_block:
                folio_put_refs(sum_folio, 2);
                segno = block_end_segno;
        }

        if (submitted)
                f2fs_submit_merged_write(sbi, data_type);

        blk_finish_plug(&plug);

        if (migrated)
                stat_inc_gc_sec_count(sbi, data_type, gc_type);

        return seg_freed;
}

int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control)
{
        int gc_type = gc_control->init_gc_type;
        unsigned int segno = gc_control->victim_segno;
        int sec_freed = 0, seg_freed = 0, total_freed = 0, total_sec_freed = 0;
        int ret = 0;
        struct cp_control cpc;
        struct gc_inode_list gc_list = {
                .ilist = LIST_HEAD_INIT(gc_list.ilist),
                .iroot = RADIX_TREE_INIT(gc_list.iroot, GFP_NOFS),
        };
        unsigned int skipped_round = 0, round = 0;
        unsigned int upper_secs;

        trace_f2fs_gc_begin(sbi->sb, gc_type, gc_control->no_bg_gc,
                                gc_control->nr_free_secs,
                                get_pages(sbi, F2FS_DIRTY_NODES),
                                get_pages(sbi, F2FS_DIRTY_DENTS),
                                get_pages(sbi, F2FS_DIRTY_IMETA),
                                free_sections(sbi),
                                free_segments(sbi),
                                reserved_segments(sbi),
                                prefree_segments(sbi));

        cpc.reason = __get_cp_reason(sbi);
gc_more:
        sbi->skipped_gc_rwsem = 0;
        if (unlikely(!(sbi->sb->s_flags & SB_ACTIVE))) {
                ret = -EINVAL;
                goto stop;
        }
        if (unlikely(f2fs_cp_error(sbi))) {
                ret = -EIO;
                goto stop;
        }

        /* Let's run FG_GC, if we don't have enough space. */
        if (has_not_enough_free_secs(sbi, 0, 0)) {
                gc_type = FG_GC;
                gc_control->one_time = false;

                /*
                 * For example, if there are many prefree_segments below given
                 * threshold, we can make them free by checkpoint. Then, we
                 * secure free segments which doesn't need fggc any more.
                 */
                if (prefree_segments(sbi)) {
                        stat_inc_cp_call_count(sbi, TOTAL_CALL);
                        ret = f2fs_write_checkpoint(sbi, &cpc);
                        if (ret)
                                goto stop;
                        /* Reset due to checkpoint */
                        sec_freed = 0;
                }
        }

        /* f2fs_balance_fs doesn't need to do BG_GC in critical path. */
        if (gc_type == BG_GC && gc_control->no_bg_gc) {
                ret = -EINVAL;
                goto stop;
        }
retry:
        ret = __get_victim(sbi, &segno, gc_type, gc_control->one_time);
        if (ret) {
                /* allow to search victim from sections has pinned data */
                if (ret == -ENODATA && gc_type == FG_GC &&
                                f2fs_pinned_section_exists(DIRTY_I(sbi))) {
                        f2fs_unpin_all_sections(sbi, false);
                        goto retry;
                }
                goto stop;
        }

        seg_freed = do_garbage_collect(sbi, segno, &gc_list, gc_type,
                                gc_control->should_migrate_blocks,
                                gc_control->one_time);
        if (seg_freed < 0)
                goto stop;

        total_freed += seg_freed;

        if (seg_freed == f2fs_usable_segs_in_sec(sbi)) {
                sec_freed++;
                total_sec_freed++;
        }

        if (gc_control->one_time)
                goto stop;

        if (gc_type == FG_GC) {
                sbi->cur_victim_sec = NULL_SEGNO;

                if (has_enough_free_secs(sbi, sec_freed, 0)) {
                        if (!gc_control->no_bg_gc &&
                            total_sec_freed < gc_control->nr_free_secs)
                                goto go_gc_more;
                        goto stop;
                }
                if (sbi->skipped_gc_rwsem)
                        skipped_round++;
                round++;
                if (skipped_round > MAX_SKIP_GC_COUNT &&
                                skipped_round * 2 >= round) {
                        stat_inc_cp_call_count(sbi, TOTAL_CALL);
                        ret = f2fs_write_checkpoint(sbi, &cpc);
                        goto stop;
                }
        } else if (has_enough_free_secs(sbi, 0, 0)) {
                goto stop;
        }

        upper_secs = __get_secs_required(sbi);

        /*
         * Write checkpoint to reclaim prefree segments.
         * We need more three extra sections for writer's data/node/dentry.
         */
        if (free_sections(sbi) <= upper_secs + NR_GC_CHECKPOINT_SECS &&
                                prefree_segments(sbi)) {
                stat_inc_cp_call_count(sbi, TOTAL_CALL);
                ret = f2fs_write_checkpoint(sbi, &cpc);
                if (ret)
                        goto stop;
                /* Reset due to checkpoint */
                sec_freed = 0;
        }
go_gc_more:
        segno = NULL_SEGNO;
        goto gc_more;

stop:
        SIT_I(sbi)->last_victim[ALLOC_NEXT] = 0;
        SIT_I(sbi)->last_victim[FLUSH_DEVICE] = gc_control->victim_segno;

        if (gc_type == FG_GC)
                f2fs_unpin_all_sections(sbi, true);

        trace_f2fs_gc_end(sbi->sb, ret, total_freed, total_sec_freed,
                                get_pages(sbi, F2FS_DIRTY_NODES),
                                get_pages(sbi, F2FS_DIRTY_DENTS),
                                get_pages(sbi, F2FS_DIRTY_IMETA),
                                free_sections(sbi),
                                free_segments(sbi),
                                reserved_segments(sbi),
                                prefree_segments(sbi));

        f2fs_up_write_trace(&sbi->gc_lock, &gc_control->lc);

        put_gc_inode(&gc_list);

        if (gc_control->err_gc_skipped && !ret)
                ret = total_sec_freed ? 0 : -EAGAIN;
        return ret;
}

int __init f2fs_create_garbage_collection_cache(void)
{
        victim_entry_slab = f2fs_kmem_cache_create("f2fs_victim_entry",
                                        sizeof(struct victim_entry));
        return victim_entry_slab ? 0 : -ENOMEM;
}

void f2fs_destroy_garbage_collection_cache(void)
{
        kmem_cache_destroy(victim_entry_slab);
}

static void init_atgc_management(struct f2fs_sb_info *sbi)
{
        struct atgc_management *am = &sbi->am;

        if (test_opt(sbi, ATGC) &&
                SIT_I(sbi)->elapsed_time >= DEF_GC_THREAD_AGE_THRESHOLD)
                am->atgc_enabled = true;

        am->root = RB_ROOT_CACHED;
        INIT_LIST_HEAD(&am->victim_list);
        am->victim_count = 0;

        am->candidate_ratio = DEF_GC_THREAD_CANDIDATE_RATIO;
        am->max_candidate_count = DEF_GC_THREAD_MAX_CANDIDATE_COUNT;
        am->age_weight = DEF_GC_THREAD_AGE_WEIGHT;
        am->age_threshold = DEF_GC_THREAD_AGE_THRESHOLD;
}

void f2fs_build_gc_manager(struct f2fs_sb_info *sbi)
{
        sbi->gc_pin_file_threshold = DEF_GC_FAILED_PINNED_FILES;

        /* give warm/cold data area from slower device */
        if (f2fs_is_multi_device(sbi) && !__is_large_section(sbi))
                SIT_I(sbi)->last_victim[ALLOC_NEXT] =
                                GET_SEGNO(sbi, FDEV(0).end_blk) + 1;

        init_atgc_management(sbi);
}

int f2fs_gc_range(struct f2fs_sb_info *sbi,
                unsigned int start_seg, unsigned int end_seg,
                bool dry_run, unsigned int dry_run_sections)
{
        unsigned int segno;
        unsigned int gc_secs = dry_run_sections;

        if (unlikely(f2fs_cp_error(sbi)))
                return -EIO;

        stat_inc_gc_call_count(sbi, FOREGROUND);
        for (segno = start_seg; segno <= end_seg; segno += SEGS_PER_SEC(sbi)) {
                struct gc_inode_list gc_list = {
                        .ilist = LIST_HEAD_INIT(gc_list.ilist),
                        .iroot = RADIX_TREE_INIT(gc_list.iroot, GFP_NOFS),
                };

                /*
                 * avoid migrating empty section, as it can be allocated by
                 * log in parallel.
                 */
                if (!get_valid_blocks(sbi, segno, true))
                        continue;

                if (is_cursec(sbi, GET_SEC_FROM_SEG(sbi, segno)))
                        continue;

                do_garbage_collect(sbi, segno, &gc_list, FG_GC, true, false);
                put_gc_inode(&gc_list);

                if (!dry_run && get_valid_blocks(sbi, segno, true))
                        return -EAGAIN;
                if (dry_run && dry_run_sections &&
                    !get_valid_blocks(sbi, segno, true) && --gc_secs == 0)
                        break;

                if (fatal_signal_pending(current))
                        return -ERESTARTSYS;
        }

        return 0;
}

static int free_segment_range(struct f2fs_sb_info *sbi,
                                unsigned int secs, bool dry_run)
{
        unsigned int next_inuse, start, end;
        struct cp_control cpc = { CP_RESIZE, 0, 0, 0 };
        int gc_mode, gc_type;
        int err = 0;
        int type;

        /* Force block allocation for GC */
        MAIN_SECS(sbi) -= secs;
        start = MAIN_SECS(sbi) * SEGS_PER_SEC(sbi);
        end = MAIN_SEGS(sbi) - 1;

        mutex_lock(&DIRTY_I(sbi)->seglist_lock);
        for (gc_mode = 0; gc_mode < MAX_GC_POLICY; gc_mode++)
                if (SIT_I(sbi)->last_victim[gc_mode] >= start)
                        SIT_I(sbi)->last_victim[gc_mode] = 0;

        for (gc_type = BG_GC; gc_type <= FG_GC; gc_type++)
                if (sbi->next_victim_seg[gc_type] >= start)
                        sbi->next_victim_seg[gc_type] = NULL_SEGNO;
        mutex_unlock(&DIRTY_I(sbi)->seglist_lock);

        /* Move out cursegs from the target range */
        for (type = CURSEG_HOT_DATA; type < NR_CURSEG_PERSIST_TYPE; type++) {
                err = f2fs_allocate_segment_for_resize(sbi, type, start, end);
                if (err)
                        goto out;
        }

        /* do GC to move out valid blocks in the range */
        err = f2fs_gc_range(sbi, start, end, dry_run, 0);
        if (err || dry_run)
                goto out;

        stat_inc_cp_call_count(sbi, TOTAL_CALL);
        err = f2fs_write_checkpoint(sbi, &cpc);
        if (err)
                goto out;

        next_inuse = find_next_inuse(FREE_I(sbi), end + 1, start);
        if (next_inuse <= end) {
                f2fs_err(sbi, "segno %u should be free but still inuse!",
                         next_inuse);
                f2fs_bug_on(sbi, 1);
        }
out:
        MAIN_SECS(sbi) += secs;
        return err;
}

static void update_sb_metadata(struct f2fs_sb_info *sbi, int secs)
{
        struct f2fs_super_block *raw_sb = F2FS_RAW_SUPER(sbi);
        int section_count;
        int segment_count;
        int segment_count_main;
        long long block_count;
        int segs = secs * SEGS_PER_SEC(sbi);

        f2fs_down_write(&sbi->sb_lock);

        section_count = le32_to_cpu(raw_sb->section_count);
        segment_count = le32_to_cpu(raw_sb->segment_count);
        segment_count_main = le32_to_cpu(raw_sb->segment_count_main);
        block_count = le64_to_cpu(raw_sb->block_count);

        raw_sb->section_count = cpu_to_le32(section_count + secs);
        raw_sb->segment_count = cpu_to_le32(segment_count + segs);
        raw_sb->segment_count_main = cpu_to_le32(segment_count_main + segs);
        raw_sb->block_count = cpu_to_le64(block_count +
                        (long long)SEGS_TO_BLKS(sbi, segs));
        if (f2fs_is_multi_device(sbi)) {
                int last_dev = sbi->s_ndevs - 1;
                int dev_segs =
                        le32_to_cpu(raw_sb->devs[last_dev].total_segments);

                raw_sb->devs[last_dev].total_segments =
                                                cpu_to_le32(dev_segs + segs);
        }

        f2fs_up_write(&sbi->sb_lock);
}

static void update_fs_metadata(struct f2fs_sb_info *sbi, int secs)
{
        int segs = secs * SEGS_PER_SEC(sbi);
        long long blks = SEGS_TO_BLKS(sbi, segs);
        long long user_block_count =
                                le64_to_cpu(F2FS_CKPT(sbi)->user_block_count);

        SM_I(sbi)->segment_count = (int)SM_I(sbi)->segment_count + segs;
        MAIN_SEGS(sbi) = (int)MAIN_SEGS(sbi) + segs;
        MAIN_SECS(sbi) += secs;
        if (sbi->allocate_section_hint > MAIN_SECS(sbi))
                sbi->allocate_section_hint = MAIN_SECS(sbi);
        FREE_I(sbi)->free_sections = (int)FREE_I(sbi)->free_sections + secs;
        FREE_I(sbi)->free_segments = (int)FREE_I(sbi)->free_segments + segs;
        F2FS_CKPT(sbi)->user_block_count = cpu_to_le64(user_block_count + blks);

        if (f2fs_is_multi_device(sbi)) {
                int last_dev = sbi->s_ndevs - 1;

                sbi->allocate_section_hint = FDEV(0).total_segments /
                                        SEGS_PER_SEC(sbi);

                FDEV(last_dev).total_segments =
                                (int)FDEV(last_dev).total_segments + segs;
                FDEV(last_dev).end_blk =
                                (long long)FDEV(last_dev).end_blk + blks;
#ifdef CONFIG_BLK_DEV_ZONED
                FDEV(last_dev).nr_blkz = FDEV(last_dev).nr_blkz +
                                        div_u64(blks, sbi->blocks_per_blkz);
#endif
        }
}

int f2fs_resize_fs(struct file *filp, __u64 block_count)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(file_inode(filp));
        __u64 old_block_count, shrunk_blocks;
        struct cp_control cpc = { CP_RESIZE, 0, 0, 0 };
        struct f2fs_lock_context lc;
        struct f2fs_lock_context glc;
        struct f2fs_lock_context clc;
        unsigned int secs;
        int err = 0;
        __u32 rem;

        old_block_count = le64_to_cpu(F2FS_RAW_SUPER(sbi)->block_count);
        if (block_count > old_block_count)
                return -EINVAL;

        if (f2fs_is_multi_device(sbi)) {
                int last_dev = sbi->s_ndevs - 1;
                __u64 last_segs = FDEV(last_dev).total_segments;

                if (block_count + SEGS_TO_BLKS(sbi, last_segs) <=
                                                                old_block_count)
                        return -EINVAL;
        }

        /* new fs size should align to section size */
        div_u64_rem(block_count, BLKS_PER_SEC(sbi), &rem);
        if (rem)
                return -EINVAL;

        if (block_count == old_block_count)
                return 0;

        if (is_sbi_flag_set(sbi, SBI_NEED_FSCK)) {
                f2fs_err(sbi, "Should run fsck to repair first.");
                return -EFSCORRUPTED;
        }

        if (test_opt(sbi, DISABLE_CHECKPOINT)) {
                f2fs_err(sbi, "Checkpoint should be enabled.");
                return -EINVAL;
        }

        err = mnt_want_write_file(filp);
        if (err)
                return err;

        shrunk_blocks = old_block_count - block_count;
        secs = div_u64(shrunk_blocks, BLKS_PER_SEC(sbi));

        /* stop other GC */
        if (!f2fs_down_write_trylock_trace(&sbi->gc_lock, &glc)) {
                err = -EAGAIN;
                goto out_drop_write;
        }

        /* stop CP to protect MAIN_SEC in free_segment_range */
        f2fs_lock_op(sbi, &lc);

        spin_lock(&sbi->stat_lock);
        if (shrunk_blocks + valid_user_blocks(sbi) +
                sbi->current_reserved_blocks + sbi->unusable_block_count +
                F2FS_OPTION(sbi).root_reserved_blocks > sbi->user_block_count)
                err = -ENOSPC;
        spin_unlock(&sbi->stat_lock);

        if (err)
                goto out_unlock;

        err = free_segment_range(sbi, secs, true);

out_unlock:
        f2fs_unlock_op(sbi, &lc);
        f2fs_up_write_trace(&sbi->gc_lock, &glc);
out_drop_write:
        mnt_drop_write_file(filp);
        if (err)
                return err;

        err = freeze_super(sbi->sb, FREEZE_HOLDER_KERNEL, NULL);
        if (err)
                return err;

        if (f2fs_readonly(sbi->sb)) {
                err = thaw_super(sbi->sb, FREEZE_HOLDER_KERNEL, NULL);
                if (err)
                        return err;
                return -EROFS;
        }

        f2fs_down_write_trace(&sbi->gc_lock, &glc);
        f2fs_down_write_trace(&sbi->cp_global_sem, &clc);

        spin_lock(&sbi->stat_lock);
        if (shrunk_blocks + valid_user_blocks(sbi) +
                sbi->current_reserved_blocks + sbi->unusable_block_count +
                F2FS_OPTION(sbi).root_reserved_blocks > sbi->user_block_count)
                err = -ENOSPC;
        else
                sbi->user_block_count -= shrunk_blocks;
        spin_unlock(&sbi->stat_lock);
        if (err)
                goto out_err;

        set_sbi_flag(sbi, SBI_IS_RESIZEFS);
        err = free_segment_range(sbi, secs, false);
        if (err)
                goto recover_out;

        update_sb_metadata(sbi, -secs);

        err = f2fs_commit_super(sbi, false);
        if (err) {
                update_sb_metadata(sbi, secs);
                goto recover_out;
        }

        update_fs_metadata(sbi, -secs);
        clear_sbi_flag(sbi, SBI_IS_RESIZEFS);
        set_sbi_flag(sbi, SBI_IS_DIRTY);

        stat_inc_cp_call_count(sbi, TOTAL_CALL);
        err = f2fs_write_checkpoint(sbi, &cpc);
        if (err) {
                update_fs_metadata(sbi, secs);
                update_sb_metadata(sbi, secs);
                f2fs_commit_super(sbi, false);
        }
recover_out:
        clear_sbi_flag(sbi, SBI_IS_RESIZEFS);
        if (err) {
                set_sbi_flag(sbi, SBI_NEED_FSCK);
                f2fs_err(sbi, "resize_fs failed, should run fsck to repair!");

                spin_lock(&sbi->stat_lock);
                sbi->user_block_count += shrunk_blocks;
                spin_unlock(&sbi->stat_lock);
        }
out_err:
        f2fs_up_write_trace(&sbi->cp_global_sem, &clc);
        f2fs_up_write_trace(&sbi->gc_lock, &glc);
        thaw_super(sbi->sb, FREEZE_HOLDER_KERNEL, NULL);
        return err;
}