/*
 * fs/f2fs/segment.c
 *
 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
 *             http://www.samsung.com/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/fs.h>
#include <linux/f2fs_fs.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/prefetch.h>
#include <linux/kthread.h>
#include <linux/swap.h>
#include <linux/timer.h>

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

#define __reverse_ffz(x) __reverse_ffs(~(x))

static struct kmem_cache *discard_entry_slab;
static struct kmem_cache *bio_entry_slab;
static struct kmem_cache *sit_entry_set_slab;
static struct kmem_cache *inmem_entry_slab;

static unsigned long __reverse_ulong(unsigned char *str)
{
        unsigned long tmp = 0;
        int shift = 24, idx = 0;

#if BITS_PER_LONG == 64
        shift = 56;
#endif
        while (shift >= 0) {
                tmp |= (unsigned long)str[idx++] << shift;
                shift -= BITS_PER_BYTE;
        }
        return tmp;
}

/*
 * __reverse_ffs is copied from include/asm-generic/bitops/__ffs.h since
 * MSB and LSB are reversed in a byte by f2fs_set_bit.
 */
static inline unsigned long __reverse_ffs(unsigned long word)
{
        int num = 0;

#if BITS_PER_LONG == 64
        if ((word & 0xffffffff00000000UL) == 0)
                num += 32;
        else
                word >>= 32;
#endif
        if ((word & 0xffff0000) == 0)
                num += 16;
        else
                word >>= 16;

        if ((word & 0xff00) == 0)
                num += 8;
        else
                word >>= 8;

        if ((word & 0xf0) == 0)
                num += 4;
        else
                word >>= 4;

        if ((word & 0xc) == 0)
                num += 2;
        else
                word >>= 2;

        if ((word & 0x2) == 0)
                num += 1;
        return num;
}

/*
 * __find_rev_next(_zero)_bit is copied from lib/find_next_bit.c because
 * f2fs_set_bit makes MSB and LSB reversed in a byte.
 * @size must be integral times of unsigned long.
 * Example:
 *                             MSB <--> LSB
 *   f2fs_set_bit(0, bitmap) => 1000 0000
 *   f2fs_set_bit(7, bitmap) => 0000 0001
 */
static unsigned long __find_rev_next_bit(const unsigned long *addr,
                        unsigned long size, unsigned long offset)
{
        const unsigned long *p = addr + BIT_WORD(offset);
        unsigned long result = size;
        unsigned long tmp;

        if (offset >= size)
                return size;

        size -= (offset & ~(BITS_PER_LONG - 1));
        offset %= BITS_PER_LONG;

        while (1) {
                if (*p == 0)
                        goto pass;

                tmp = __reverse_ulong((unsigned char *)p);

                tmp &= ~0UL >> offset;
                if (size < BITS_PER_LONG)
                        tmp &= (~0UL << (BITS_PER_LONG - size));
                if (tmp)
                        goto found;
pass:
                if (size <= BITS_PER_LONG)
                        break;
                size -= BITS_PER_LONG;
                offset = 0;
                p++;
        }
        return result;
found:
        return result - size + __reverse_ffs(tmp);
}

static unsigned long __find_rev_next_zero_bit(const unsigned long *addr,
                        unsigned long size, unsigned long offset)
{
        const unsigned long *p = addr + BIT_WORD(offset);
        unsigned long result = size;
        unsigned long tmp;

        if (offset >= size)
                return size;

        size -= (offset & ~(BITS_PER_LONG - 1));
        offset %= BITS_PER_LONG;

        while (1) {
                if (*p == ~0UL)
                        goto pass;

                tmp = __reverse_ulong((unsigned char *)p);

                if (offset)
                        tmp |= ~0UL << (BITS_PER_LONG - offset);
                if (size < BITS_PER_LONG)
                        tmp |= ~0UL >> size;
                if (tmp != ~0UL)
                        goto found;
pass:
                if (size <= BITS_PER_LONG)
                        break;
                size -= BITS_PER_LONG;
                offset = 0;
                p++;
        }
        return result;
found:
        return result - size + __reverse_ffz(tmp);
}

void register_inmem_page(struct inode *inode, struct page *page)
{
        struct f2fs_inode_info *fi = F2FS_I(inode);
        struct inmem_pages *new;

        f2fs_trace_pid(page);

        set_page_private(page, (unsigned long)ATOMIC_WRITTEN_PAGE);
        SetPagePrivate(page);

        new = f2fs_kmem_cache_alloc(inmem_entry_slab, GFP_NOFS);

        /* add atomic page indices to the list */
        new->page = page;
        INIT_LIST_HEAD(&new->list);

        /* increase reference count with clean state */
        mutex_lock(&fi->inmem_lock);
        get_page(page);
        list_add_tail(&new->list, &fi->inmem_pages);
        inc_page_count(F2FS_I_SB(inode), F2FS_INMEM_PAGES);
        mutex_unlock(&fi->inmem_lock);

        trace_f2fs_register_inmem_page(page, INMEM);
}

static int __revoke_inmem_pages(struct inode *inode,
                                struct list_head *head, bool drop, bool recover)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct inmem_pages *cur, *tmp;
        int err = 0;

        list_for_each_entry_safe(cur, tmp, head, list) {
                struct page *page = cur->page;

                if (drop)
                        trace_f2fs_commit_inmem_page(page, INMEM_DROP);

                lock_page(page);

                if (recover) {
                        struct dnode_of_data dn;
                        struct node_info ni;

                        trace_f2fs_commit_inmem_page(page, INMEM_REVOKE);

                        set_new_dnode(&dn, inode, NULL, NULL, 0);
                        if (get_dnode_of_data(&dn, page->index, LOOKUP_NODE)) {
                                err = -EAGAIN;
                                goto next;
                        }
                        get_node_info(sbi, dn.nid, &ni);
                        f2fs_replace_block(sbi, &dn, dn.data_blkaddr,
                                        cur->old_addr, ni.version, true, true);
                        f2fs_put_dnode(&dn);
                }
next:
                /* we don't need to invalidate this in the sccessful status */
                if (drop || recover)
                        ClearPageUptodate(page);
                set_page_private(page, 0);
                ClearPagePrivate(page);
                f2fs_put_page(page, 1);

                list_del(&cur->list);
                kmem_cache_free(inmem_entry_slab, cur);
                dec_page_count(F2FS_I_SB(inode), F2FS_INMEM_PAGES);
        }
        return err;
}

void drop_inmem_pages(struct inode *inode)
{
        struct f2fs_inode_info *fi = F2FS_I(inode);

        clear_inode_flag(inode, FI_ATOMIC_FILE);

        mutex_lock(&fi->inmem_lock);
        __revoke_inmem_pages(inode, &fi->inmem_pages, true, false);
        mutex_unlock(&fi->inmem_lock);
}

static int __commit_inmem_pages(struct inode *inode,
                                        struct list_head *revoke_list)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct f2fs_inode_info *fi = F2FS_I(inode);
        struct inmem_pages *cur, *tmp;
        struct f2fs_io_info fio = {
                .sbi = sbi,
                .type = DATA,
                .op = REQ_OP_WRITE,
                .op_flags = REQ_SYNC | REQ_PRIO,
                .encrypted_page = NULL,
        };
        bool submit_bio = false;
        int err = 0;

        list_for_each_entry_safe(cur, tmp, &fi->inmem_pages, list) {
                struct page *page = cur->page;

                lock_page(page);
                if (page->mapping == inode->i_mapping) {
                        trace_f2fs_commit_inmem_page(page, INMEM);

                        set_page_dirty(page);
                        f2fs_wait_on_page_writeback(page, DATA, true);
                        if (clear_page_dirty_for_io(page)) {
                                inode_dec_dirty_pages(inode);
                                remove_dirty_inode(inode);
                        }

                        fio.page = page;
                        err = do_write_data_page(&fio);
                        if (err) {
                                unlock_page(page);
                                break;
                        }

                        /* record old blkaddr for revoking */
                        cur->old_addr = fio.old_blkaddr;

                        submit_bio = true;
                }
                unlock_page(page);
                list_move_tail(&cur->list, revoke_list);
        }

        if (submit_bio)
                f2fs_submit_merged_bio_cond(sbi, inode, NULL, 0, DATA, WRITE);

        if (!err)
                __revoke_inmem_pages(inode, revoke_list, false, false);

        return err;
}

int commit_inmem_pages(struct inode *inode)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct f2fs_inode_info *fi = F2FS_I(inode);
        struct list_head revoke_list;
        int err;

        INIT_LIST_HEAD(&revoke_list);
        f2fs_balance_fs(sbi, true);
        f2fs_lock_op(sbi);

        mutex_lock(&fi->inmem_lock);
        err = __commit_inmem_pages(inode, &revoke_list);
        if (err) {
                int ret;
                /*
                 * try to revoke all committed pages, but still we could fail
                 * due to no memory or other reason, if that happened, EAGAIN
                 * will be returned, which means in such case, transaction is
                 * already not integrity, caller should use journal to do the
                 * recovery or rewrite & commit last transaction. For other
                 * error number, revoking was done by filesystem itself.
                 */
                ret = __revoke_inmem_pages(inode, &revoke_list, false, true);
                if (ret)
                        err = ret;

                /* drop all uncommitted pages */
                __revoke_inmem_pages(inode, &fi->inmem_pages, true, false);
        }
        mutex_unlock(&fi->inmem_lock);

        f2fs_unlock_op(sbi);
        return err;
}

/*
 * This function balances dirty node and dentry pages.
 * In addition, it controls garbage collection.
 */
void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need)
{
#ifdef CONFIG_F2FS_FAULT_INJECTION
        if (time_to_inject(sbi, FAULT_CHECKPOINT))
                f2fs_stop_checkpoint(sbi, false);
#endif

        if (!need)
                return;

        /* balance_fs_bg is able to be pending */
        if (excess_cached_nats(sbi))
                f2fs_balance_fs_bg(sbi);

        /*
         * We should do GC or end up with checkpoint, if there are so many dirty
         * dir/node pages without enough free segments.
         */
        if (has_not_enough_free_secs(sbi, 0, 0)) {
                mutex_lock(&sbi->gc_mutex);
                f2fs_gc(sbi, false, false);
        }
}

void f2fs_balance_fs_bg(struct f2fs_sb_info *sbi)
{
        /* try to shrink extent cache when there is no enough memory */
        if (!available_free_memory(sbi, EXTENT_CACHE))
                f2fs_shrink_extent_tree(sbi, EXTENT_CACHE_SHRINK_NUMBER);

        /* check the # of cached NAT entries */
        if (!available_free_memory(sbi, NAT_ENTRIES))
                try_to_free_nats(sbi, NAT_ENTRY_PER_BLOCK);

        if (!available_free_memory(sbi, FREE_NIDS))
                try_to_free_nids(sbi, MAX_FREE_NIDS);
        else
                build_free_nids(sbi, false);

        if (!is_idle(sbi))
                return;

        /* checkpoint is the only way to shrink partial cached entries */
        if (!available_free_memory(sbi, NAT_ENTRIES) ||
                        !available_free_memory(sbi, INO_ENTRIES) ||
                        excess_prefree_segs(sbi) ||
                        excess_dirty_nats(sbi) ||
                        f2fs_time_over(sbi, CP_TIME)) {
                if (test_opt(sbi, DATA_FLUSH)) {
                        struct blk_plug plug;

                        blk_start_plug(&plug);
                        sync_dirty_inodes(sbi, FILE_INODE);
                        blk_finish_plug(&plug);
                }
                f2fs_sync_fs(sbi->sb, true);
                stat_inc_bg_cp_count(sbi->stat_info);
        }
}

static int __submit_flush_wait(struct block_device *bdev)
{
        struct bio *bio = f2fs_bio_alloc(0);
        int ret;

        bio->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
        bio->bi_bdev = bdev;
        ret = submit_bio_wait(bio);
        bio_put(bio);
        return ret;
}

static int submit_flush_wait(struct f2fs_sb_info *sbi)
{
        int ret = __submit_flush_wait(sbi->sb->s_bdev);
        int i;

        if (sbi->s_ndevs && !ret) {
                for (i = 1; i < sbi->s_ndevs; i++) {
                        ret = __submit_flush_wait(FDEV(i).bdev);
                        if (ret)
                                break;
                }
        }
        return ret;
}

static int issue_flush_thread(void *data)
{
        struct f2fs_sb_info *sbi = data;
        struct flush_cmd_control *fcc = SM_I(sbi)->cmd_control_info;
        wait_queue_head_t *q = &fcc->flush_wait_queue;
repeat:
        if (kthread_should_stop())
                return 0;

        if (!llist_empty(&fcc->issue_list)) {
                struct flush_cmd *cmd, *next;
                int ret;

                fcc->dispatch_list = llist_del_all(&fcc->issue_list);
                fcc->dispatch_list = llist_reverse_order(fcc->dispatch_list);

                ret = submit_flush_wait(sbi);
                llist_for_each_entry_safe(cmd, next,
                                          fcc->dispatch_list, llnode) {
                        cmd->ret = ret;
                        complete(&cmd->wait);
                }
                fcc->dispatch_list = NULL;
        }

        wait_event_interruptible(*q,
                kthread_should_stop() || !llist_empty(&fcc->issue_list));
        goto repeat;
}

int f2fs_issue_flush(struct f2fs_sb_info *sbi)
{
        struct flush_cmd_control *fcc = SM_I(sbi)->cmd_control_info;
        struct flush_cmd cmd;

        trace_f2fs_issue_flush(sbi->sb, test_opt(sbi, NOBARRIER),
                                        test_opt(sbi, FLUSH_MERGE));

        if (test_opt(sbi, NOBARRIER))
                return 0;

        if (!test_opt(sbi, FLUSH_MERGE) || !atomic_read(&fcc->submit_flush)) {
                int ret;

                atomic_inc(&fcc->submit_flush);
                ret = submit_flush_wait(sbi);
                atomic_dec(&fcc->submit_flush);
                return ret;
        }

        init_completion(&cmd.wait);

        atomic_inc(&fcc->submit_flush);
        llist_add(&cmd.llnode, &fcc->issue_list);

        if (!fcc->dispatch_list)
                wake_up(&fcc->flush_wait_queue);

        if (fcc->f2fs_issue_flush) {
                wait_for_completion(&cmd.wait);
                atomic_dec(&fcc->submit_flush);
        } else {
                llist_del_all(&fcc->issue_list);
                atomic_set(&fcc->submit_flush, 0);
        }

        return cmd.ret;
}

int create_flush_cmd_control(struct f2fs_sb_info *sbi)
{
        dev_t dev = sbi->sb->s_bdev->bd_dev;
        struct flush_cmd_control *fcc;
        int err = 0;

        if (SM_I(sbi)->cmd_control_info) {
                fcc = SM_I(sbi)->cmd_control_info;
                goto init_thread;
        }

        fcc = kzalloc(sizeof(struct flush_cmd_control), GFP_KERNEL);
        if (!fcc)
                return -ENOMEM;
        atomic_set(&fcc->submit_flush, 0);
        init_waitqueue_head(&fcc->flush_wait_queue);
        init_llist_head(&fcc->issue_list);
        SM_I(sbi)->cmd_control_info = fcc;
init_thread:
        fcc->f2fs_issue_flush = kthread_run(issue_flush_thread, sbi,
                                "f2fs_flush-%u:%u", MAJOR(dev), MINOR(dev));
        if (IS_ERR(fcc->f2fs_issue_flush)) {
                err = PTR_ERR(fcc->f2fs_issue_flush);
                kfree(fcc);
                SM_I(sbi)->cmd_control_info = NULL;
                return err;
        }

        return err;
}

void destroy_flush_cmd_control(struct f2fs_sb_info *sbi, bool free)
{
        struct flush_cmd_control *fcc = SM_I(sbi)->cmd_control_info;

        if (fcc && fcc->f2fs_issue_flush) {
                struct task_struct *flush_thread = fcc->f2fs_issue_flush;

                fcc->f2fs_issue_flush = NULL;
                kthread_stop(flush_thread);
        }
        if (free) {
                kfree(fcc);
                SM_I(sbi)->cmd_control_info = NULL;
        }
}

static void __locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
                enum dirty_type dirty_type)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);

        /* need not be added */
        if (IS_CURSEG(sbi, segno))
                return;

        if (!test_and_set_bit(segno, dirty_i->dirty_segmap[dirty_type]))
                dirty_i->nr_dirty[dirty_type]++;

        if (dirty_type == DIRTY) {
                struct seg_entry *sentry = get_seg_entry(sbi, segno);
                enum dirty_type t = sentry->type;

                if (unlikely(t >= DIRTY)) {
                        f2fs_bug_on(sbi, 1);
                        return;
                }
                if (!test_and_set_bit(segno, dirty_i->dirty_segmap[t]))
                        dirty_i->nr_dirty[t]++;
        }
}

static void __remove_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
                enum dirty_type dirty_type)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);

        if (test_and_clear_bit(segno, dirty_i->dirty_segmap[dirty_type]))
                dirty_i->nr_dirty[dirty_type]--;

        if (dirty_type == DIRTY) {
                struct seg_entry *sentry = get_seg_entry(sbi, segno);
                enum dirty_type t = sentry->type;

                if (test_and_clear_bit(segno, dirty_i->dirty_segmap[t]))
                        dirty_i->nr_dirty[t]--;

                if (get_valid_blocks(sbi, segno, sbi->segs_per_sec) == 0)
                        clear_bit(GET_SECNO(sbi, segno),
                                                dirty_i->victim_secmap);
        }
}

/*
 * Should not occur error such as -ENOMEM.
 * Adding dirty entry into seglist is not critical operation.
 * If a given segment is one of current working segments, it won't be added.
 */
static void locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
        unsigned short valid_blocks;

        if (segno == NULL_SEGNO || IS_CURSEG(sbi, segno))
                return;

        mutex_lock(&dirty_i->seglist_lock);

        valid_blocks = get_valid_blocks(sbi, segno, 0);

        if (valid_blocks == 0) {
                __locate_dirty_segment(sbi, segno, PRE);
                __remove_dirty_segment(sbi, segno, DIRTY);
        } else if (valid_blocks < sbi->blocks_per_seg) {
                __locate_dirty_segment(sbi, segno, DIRTY);
        } else {
                /* Recovery routine with SSR needs this */
                __remove_dirty_segment(sbi, segno, DIRTY);
        }

        mutex_unlock(&dirty_i->seglist_lock);
}

static struct bio_entry *__add_bio_entry(struct f2fs_sb_info *sbi,
                                                        struct bio *bio)
{
        struct list_head *wait_list = &(SM_I(sbi)->wait_list);
        struct bio_entry *be = f2fs_kmem_cache_alloc(bio_entry_slab, GFP_NOFS);

        INIT_LIST_HEAD(&be->list);
        be->bio = bio;
        init_completion(&be->event);
        list_add_tail(&be->list, wait_list);

        return be;
}

void f2fs_wait_all_discard_bio(struct f2fs_sb_info *sbi)
{
        struct list_head *wait_list = &(SM_I(sbi)->wait_list);
        struct bio_entry *be, *tmp;

        list_for_each_entry_safe(be, tmp, wait_list, list) {
                struct bio *bio = be->bio;
                int err;

                wait_for_completion_io(&be->event);
                err = be->error;
                if (err == -EOPNOTSUPP)
                        err = 0;

                if (err)
                        f2fs_msg(sbi->sb, KERN_INFO,
                                "Issue discard failed, ret: %d", err);

                bio_put(bio);
                list_del(&be->list);
                kmem_cache_free(bio_entry_slab, be);
        }
}

static void f2fs_submit_bio_wait_endio(struct bio *bio)
{
        struct bio_entry *be = (struct bio_entry *)bio->bi_private;

        be->error = bio->bi_error;
        complete(&be->event);
}

/* this function is copied from blkdev_issue_discard from block/blk-lib.c */
static int __f2fs_issue_discard_async(struct f2fs_sb_info *sbi,
                struct block_device *bdev, block_t blkstart, block_t blklen)
{
        struct bio *bio = NULL;
        int err;

        trace_f2fs_issue_discard(sbi->sb, blkstart, blklen);

        if (sbi->s_ndevs) {
                int devi = f2fs_target_device_index(sbi, blkstart);

                blkstart -= FDEV(devi).start_blk;
        }
        err = __blkdev_issue_discard(bdev,
                                SECTOR_FROM_BLOCK(blkstart),
                                SECTOR_FROM_BLOCK(blklen),
                                GFP_NOFS, 0, &bio);
        if (!err && bio) {
                struct bio_entry *be = __add_bio_entry(sbi, bio);

                bio->bi_private = be;
                bio->bi_end_io = f2fs_submit_bio_wait_endio;
                bio->bi_opf |= REQ_SYNC;
                submit_bio(bio);
        }

        return err;
}

#ifdef CONFIG_BLK_DEV_ZONED
static int __f2fs_issue_discard_zone(struct f2fs_sb_info *sbi,
                struct block_device *bdev, block_t blkstart, block_t blklen)
{
        sector_t nr_sects = SECTOR_FROM_BLOCK(blklen);
        sector_t sector;
        int devi = 0;

        if (sbi->s_ndevs) {
                devi = f2fs_target_device_index(sbi, blkstart);
                blkstart -= FDEV(devi).start_blk;
        }
        sector = SECTOR_FROM_BLOCK(blkstart);

        if (sector & (bdev_zone_sectors(bdev) - 1) ||
            nr_sects != bdev_zone_sectors(bdev)) {
                f2fs_msg(sbi->sb, KERN_INFO,
                        "(%d) %s: Unaligned discard attempted (block %x + %x)",
                        devi, sbi->s_ndevs ? FDEV(devi).path: "",
                        blkstart, blklen);
                return -EIO;
        }

        /*
         * We need to know the type of the zone: for conventional zones,
         * use regular discard if the drive supports it. For sequential
         * zones, reset the zone write pointer.
         */
        switch (get_blkz_type(sbi, bdev, blkstart)) {

        case BLK_ZONE_TYPE_CONVENTIONAL:
                if (!blk_queue_discard(bdev_get_queue(bdev)))
                        return 0;
                return __f2fs_issue_discard_async(sbi, bdev, blkstart, blklen);
        case BLK_ZONE_TYPE_SEQWRITE_REQ:
        case BLK_ZONE_TYPE_SEQWRITE_PREF:
                trace_f2fs_issue_reset_zone(sbi->sb, blkstart);
                return blkdev_reset_zones(bdev, sector,
                                          nr_sects, GFP_NOFS);
        default:
                /* Unknown zone type: broken device ? */
                return -EIO;
        }
}
#endif

static int __issue_discard_async(struct f2fs_sb_info *sbi,
                struct block_device *bdev, block_t blkstart, block_t blklen)
{
#ifdef CONFIG_BLK_DEV_ZONED
        if (f2fs_sb_mounted_blkzoned(sbi->sb) &&
                                bdev_zoned_model(bdev) != BLK_ZONED_NONE)
                return __f2fs_issue_discard_zone(sbi, bdev, blkstart, blklen);
#endif
        return __f2fs_issue_discard_async(sbi, bdev, blkstart, blklen);
}

static int f2fs_issue_discard(struct f2fs_sb_info *sbi,
                                block_t blkstart, block_t blklen)
{
        sector_t start = blkstart, len = 0;
        struct block_device *bdev;
        struct seg_entry *se;
        unsigned int offset;
        block_t i;
        int err = 0;

        bdev = f2fs_target_device(sbi, blkstart, NULL);

        for (i = blkstart; i < blkstart + blklen; i++, len++) {
                if (i != start) {
                        struct block_device *bdev2 =
                                f2fs_target_device(sbi, i, NULL);

                        if (bdev2 != bdev) {
                                err = __issue_discard_async(sbi, bdev,
                                                start, len);
                                if (err)
                                        return err;
                                bdev = bdev2;
                                start = i;
                                len = 0;
                        }
                }

                se = get_seg_entry(sbi, GET_SEGNO(sbi, i));
                offset = GET_BLKOFF_FROM_SEG0(sbi, i);

                if (!f2fs_test_and_set_bit(offset, se->discard_map))
                        sbi->discard_blks--;
        }

        if (len)
                err = __issue_discard_async(sbi, bdev, start, len);
        return err;
}

static void __add_discard_entry(struct f2fs_sb_info *sbi,
                struct cp_control *cpc, struct seg_entry *se,
                unsigned int start, unsigned int end)
{
        struct list_head *head = &SM_I(sbi)->discard_list;
        struct discard_entry *new, *last;

        if (!list_empty(head)) {
                last = list_last_entry(head, struct discard_entry, list);
                if (START_BLOCK(sbi, cpc->trim_start) + start ==
                                                last->blkaddr + last->len) {
                        last->len += end - start;
                        goto done;
                }
        }

        new = f2fs_kmem_cache_alloc(discard_entry_slab, GFP_NOFS);
        INIT_LIST_HEAD(&new->list);
        new->blkaddr = START_BLOCK(sbi, cpc->trim_start) + start;
        new->len = end - start;
        list_add_tail(&new->list, head);
done:
        SM_I(sbi)->nr_discards += end - start;
}

static void add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc)
{
        int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
        int max_blocks = sbi->blocks_per_seg;
        struct seg_entry *se = get_seg_entry(sbi, cpc->trim_start);
        unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
        unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
        unsigned long *discard_map = (unsigned long *)se->discard_map;
        unsigned long *dmap = SIT_I(sbi)->tmp_map;
        unsigned int start = 0, end = -1;
        bool force = (cpc->reason == CP_DISCARD);
        int i;

        if (se->valid_blocks == max_blocks || !f2fs_discard_en(sbi))
                return;

        if (!force) {
                if (!test_opt(sbi, DISCARD) || !se->valid_blocks ||
                    SM_I(sbi)->nr_discards >= SM_I(sbi)->max_discards)
                        return;
        }

        /* SIT_VBLOCK_MAP_SIZE should be multiple of sizeof(unsigned long) */
        for (i = 0; i < entries; i++)
                dmap[i] = force ? ~ckpt_map[i] & ~discard_map[i] :
                                (cur_map[i] ^ ckpt_map[i]) & ckpt_map[i];

        while (force || SM_I(sbi)->nr_discards <= SM_I(sbi)->max_discards) {
                start = __find_rev_next_bit(dmap, max_blocks, end + 1);
                if (start >= max_blocks)
                        break;

                end = __find_rev_next_zero_bit(dmap, max_blocks, start + 1);
                if (force && start && end != max_blocks
                                        && (end - start) < cpc->trim_minlen)
                        continue;

                __add_discard_entry(sbi, cpc, se, start, end);
        }
}

void release_discard_addrs(struct f2fs_sb_info *sbi)
{
        struct list_head *head = &(SM_I(sbi)->discard_list);
        struct discard_entry *entry, *this;

        /* drop caches */
        list_for_each_entry_safe(entry, this, head, list) {
                list_del(&entry->list);
                kmem_cache_free(discard_entry_slab, entry);
        }
}

/*
 * Should call clear_prefree_segments after checkpoint is done.
 */
static void set_prefree_as_free_segments(struct f2fs_sb_info *sbi)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
        unsigned int segno;

        mutex_lock(&dirty_i->seglist_lock);
        for_each_set_bit(segno, dirty_i->dirty_segmap[PRE], MAIN_SEGS(sbi))
                __set_test_and_free(sbi, segno);
        mutex_unlock(&dirty_i->seglist_lock);
}

void clear_prefree_segments(struct f2fs_sb_info *sbi, struct cp_control *cpc)
{
        struct list_head *head = &(SM_I(sbi)->discard_list);
        struct discard_entry *entry, *this;
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
        struct blk_plug plug;
        unsigned long *prefree_map = dirty_i->dirty_segmap[PRE];
        unsigned int start = 0, end = -1;
        unsigned int secno, start_segno;
        bool force = (cpc->reason == CP_DISCARD);

        blk_start_plug(&plug);

        mutex_lock(&dirty_i->seglist_lock);

        while (1) {
                int i;
                start = find_next_bit(prefree_map, MAIN_SEGS(sbi), end + 1);
                if (start >= MAIN_SEGS(sbi))
                        break;
                end = find_next_zero_bit(prefree_map, MAIN_SEGS(sbi),
                                                                start + 1);

                for (i = start; i < end; i++)
                        clear_bit(i, prefree_map);

                dirty_i->nr_dirty[PRE] -= end - start;

                if (force || !test_opt(sbi, DISCARD))
                        continue;

                if (!test_opt(sbi, LFS) || sbi->segs_per_sec == 1) {
                        f2fs_issue_discard(sbi, START_BLOCK(sbi, start),
                                (end - start) << sbi->log_blocks_per_seg);
                        continue;
                }
next:
                secno = GET_SECNO(sbi, start);
                start_segno = secno * sbi->segs_per_sec;
                if (!IS_CURSEC(sbi, secno) &&
                        !get_valid_blocks(sbi, start, sbi->segs_per_sec))
                        f2fs_issue_discard(sbi, START_BLOCK(sbi, start_segno),
                                sbi->segs_per_sec << sbi->log_blocks_per_seg);

                start = start_segno + sbi->segs_per_sec;
                if (start < end)
                        goto next;
        }
        mutex_unlock(&dirty_i->seglist_lock);

        /* send small discards */
        list_for_each_entry_safe(entry, this, head, list) {
                if (force && entry->len < cpc->trim_minlen)
                        goto skip;
                f2fs_issue_discard(sbi, entry->blkaddr, entry->len);
                cpc->trimmed += entry->len;
skip:
                list_del(&entry->list);
                SM_I(sbi)->nr_discards -= entry->len;
                kmem_cache_free(discard_entry_slab, entry);
        }

        blk_finish_plug(&plug);
}

static bool __mark_sit_entry_dirty(struct f2fs_sb_info *sbi, unsigned int segno)
{
        struct sit_info *sit_i = SIT_I(sbi);

        if (!__test_and_set_bit(segno, sit_i->dirty_sentries_bitmap)) {
                sit_i->dirty_sentries++;
                return false;
        }

        return true;
}

static void __set_sit_entry_type(struct f2fs_sb_info *sbi, int type,
                                        unsigned int segno, int modified)
{
        struct seg_entry *se = get_seg_entry(sbi, segno);
        se->type = type;
        if (modified)
                __mark_sit_entry_dirty(sbi, segno);
}

static void update_sit_entry(struct f2fs_sb_info *sbi, block_t blkaddr, int del)
{
        struct seg_entry *se;
        unsigned int segno, offset;
        long int new_vblocks;

        segno = GET_SEGNO(sbi, blkaddr);

        se = get_seg_entry(sbi, segno);
        new_vblocks = se->valid_blocks + del;
        offset = GET_BLKOFF_FROM_SEG0(sbi, blkaddr);

        f2fs_bug_on(sbi, (new_vblocks >> (sizeof(unsigned short) << 3) ||
                                (new_vblocks > sbi->blocks_per_seg)));

        se->valid_blocks = new_vblocks;
        se->mtime = get_mtime(sbi);
        SIT_I(sbi)->max_mtime = se->mtime;

        /* Update valid block bitmap */
        if (del > 0) {
                if (f2fs_test_and_set_bit(offset, se->cur_valid_map))
                        f2fs_bug_on(sbi, 1);
                if (f2fs_discard_en(sbi) &&

                        !f2fs_test_and_set_bit(offset, se->discard_map))
                        sbi->discard_blks--;
        } else {
                if (!f2fs_test_and_clear_bit(offset, se->cur_valid_map))
                        f2fs_bug_on(sbi, 1);
                if (f2fs_discard_en(sbi) &&
                        f2fs_test_and_clear_bit(offset, se->discard_map))
                        sbi->discard_blks++;
        }
        if (!f2fs_test_bit(offset, se->ckpt_valid_map))
                se->ckpt_valid_blocks += del;

        __mark_sit_entry_dirty(sbi, segno);

        /* update total number of valid blocks to be written in ckpt area */
        SIT_I(sbi)->written_valid_blocks += del;

        if (sbi->segs_per_sec > 1)
                get_sec_entry(sbi, segno)->valid_blocks += del;
}

void refresh_sit_entry(struct f2fs_sb_info *sbi, block_t old, block_t new)
{
        update_sit_entry(sbi, new, 1);
        if (GET_SEGNO(sbi, old) != NULL_SEGNO)
                update_sit_entry(sbi, old, -1);

        locate_dirty_segment(sbi, GET_SEGNO(sbi, old));
        locate_dirty_segment(sbi, GET_SEGNO(sbi, new));
}

void invalidate_blocks(struct f2fs_sb_info *sbi, block_t addr)
{
        unsigned int segno = GET_SEGNO(sbi, addr);
        struct sit_info *sit_i = SIT_I(sbi);

        f2fs_bug_on(sbi, addr == NULL_ADDR);
        if (addr == NEW_ADDR)
                return;

        /* add it into sit main buffer */
        mutex_lock(&sit_i->sentry_lock);

        update_sit_entry(sbi, addr, -1);

        /* add it into dirty seglist */
        locate_dirty_segment(sbi, segno);

        mutex_unlock(&sit_i->sentry_lock);
}

bool is_checkpointed_data(struct f2fs_sb_info *sbi, block_t blkaddr)
{
        struct sit_info *sit_i = SIT_I(sbi);
        unsigned int segno, offset;
        struct seg_entry *se;
        bool is_cp = false;

        if (blkaddr == NEW_ADDR || blkaddr == NULL_ADDR)
                return true;

        mutex_lock(&sit_i->sentry_lock);

        segno = GET_SEGNO(sbi, blkaddr);
        se = get_seg_entry(sbi, segno);
        offset = GET_BLKOFF_FROM_SEG0(sbi, blkaddr);

        if (f2fs_test_bit(offset, se->ckpt_valid_map))
                is_cp = true;

        mutex_unlock(&sit_i->sentry_lock);

        return is_cp;
}

/*
 * This function should be resided under the curseg_mutex lock
 */
static void __add_sum_entry(struct f2fs_sb_info *sbi, int type,
                                        struct f2fs_summary *sum)
{
        struct curseg_info *curseg = CURSEG_I(sbi, type);
        void *addr = curseg->sum_blk;
        addr += curseg->next_blkoff * sizeof(struct f2fs_summary);
        memcpy(addr, sum, sizeof(struct f2fs_summary));
}

/*
 * Calculate the number of current summary pages for writing
 */
int npages_for_summary_flush(struct f2fs_sb_info *sbi, bool for_ra)
{
        int valid_sum_count = 0;
        int i, sum_in_page;

        for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
                if (sbi->ckpt->alloc_type[i] == SSR)
                        valid_sum_count += sbi->blocks_per_seg;
                else {
                        if (for_ra)
                                valid_sum_count += le16_to_cpu(
                                        F2FS_CKPT(sbi)->cur_data_blkoff[i]);
                        else
                                valid_sum_count += curseg_blkoff(sbi, i);
                }
        }

        sum_in_page = (PAGE_SIZE - 2 * SUM_JOURNAL_SIZE -
                        SUM_FOOTER_SIZE) / SUMMARY_SIZE;
        if (valid_sum_count <= sum_in_page)
                return 1;
        else if ((valid_sum_count - sum_in_page) <=
                (PAGE_SIZE - SUM_FOOTER_SIZE) / SUMMARY_SIZE)
                return 2;
        return 3;
}

/*
 * Caller should put this summary page
 */
struct page *get_sum_page(struct f2fs_sb_info *sbi, unsigned int segno)
{
        return get_meta_page(sbi, GET_SUM_BLOCK(sbi, segno));
}

void update_meta_page(struct f2fs_sb_info *sbi, void *src, block_t blk_addr)
{
        struct page *page = grab_meta_page(sbi, blk_addr);
        void *dst = page_address(page);

        if (src)
                memcpy(dst, src, PAGE_SIZE);
        else
                memset(dst, 0, PAGE_SIZE);
        set_page_dirty(page);
        f2fs_put_page(page, 1);
}

static void write_sum_page(struct f2fs_sb_info *sbi,
                        struct f2fs_summary_block *sum_blk, block_t blk_addr)
{
        update_meta_page(sbi, (void *)sum_blk, blk_addr);
}

static void write_current_sum_page(struct f2fs_sb_info *sbi,
                                                int type, block_t blk_addr)
{
        struct curseg_info *curseg = CURSEG_I(sbi, type);
        struct page *page = grab_meta_page(sbi, blk_addr);
        struct f2fs_summary_block *src = curseg->sum_blk;
        struct f2fs_summary_block *dst;

        dst = (struct f2fs_summary_block *)page_address(page);

        mutex_lock(&curseg->curseg_mutex);

        down_read(&curseg->journal_rwsem);
        memcpy(&dst->journal, curseg->journal, SUM_JOURNAL_SIZE);
        up_read(&curseg->journal_rwsem);

        memcpy(dst->entries, src->entries, SUM_ENTRY_SIZE);
        memcpy(&dst->footer, &src->footer, SUM_FOOTER_SIZE);

        mutex_unlock(&curseg->curseg_mutex);

        set_page_dirty(page);
        f2fs_put_page(page, 1);
}

static int is_next_segment_free(struct f2fs_sb_info *sbi, int type)
{
        struct curseg_info *curseg = CURSEG_I(sbi, type);
        unsigned int segno = curseg->segno + 1;
        struct free_segmap_info *free_i = FREE_I(sbi);

        if (segno < MAIN_SEGS(sbi) && segno % sbi->segs_per_sec)
                return !test_bit(segno, free_i->free_segmap);
        return 0;
}

/*
 * Find a new segment from the free segments bitmap to right order
 * This function should be returned with success, otherwise BUG
 */
static void get_new_segment(struct f2fs_sb_info *sbi,
                        unsigned int *newseg, bool new_sec, int dir)
{
        struct free_segmap_info *free_i = FREE_I(sbi);
        unsigned int segno, secno, zoneno;
        unsigned int total_zones = MAIN_SECS(sbi) / sbi->secs_per_zone;
        unsigned int hint = *newseg / sbi->segs_per_sec;
        unsigned int old_zoneno = GET_ZONENO_FROM_SEGNO(sbi, *newseg);
        unsigned int left_start = hint;
        bool init = true;
        int go_left = 0;
        int i;

        spin_lock(&free_i->segmap_lock);

        if (!new_sec && ((*newseg + 1) % sbi->segs_per_sec)) {
                segno = find_next_zero_bit(free_i->free_segmap,
                                (hint + 1) * sbi->segs_per_sec, *newseg + 1);
                if (segno < (hint + 1) * sbi->segs_per_sec)
                        goto got_it;
        }
find_other_zone:
        secno = find_next_zero_bit(free_i->free_secmap, MAIN_SECS(sbi), hint);
        if (secno >= MAIN_SECS(sbi)) {
                if (dir == ALLOC_RIGHT) {
                        secno = find_next_zero_bit(free_i->free_secmap,
                                                        MAIN_SECS(sbi), 0);
                        f2fs_bug_on(sbi, secno >= MAIN_SECS(sbi));
                } else {
                        go_left = 1;
                        left_start = hint - 1;
                }
        }
        if (go_left == 0)
                goto skip_left;

        while (test_bit(left_start, free_i->free_secmap)) {
                if (left_start > 0) {
                        left_start--;
                        continue;
                }
                left_start = find_next_zero_bit(free_i->free_secmap,
                                                        MAIN_SECS(sbi), 0);
                f2fs_bug_on(sbi, left_start >= MAIN_SECS(sbi));
                break;
        }
        secno = left_start;
skip_left:
        hint = secno;
        segno = secno * sbi->segs_per_sec;
        zoneno = secno / sbi->secs_per_zone;

        /* give up on finding another zone */
        if (!init)
                goto got_it;
        if (sbi->secs_per_zone == 1)
                goto got_it;
        if (zoneno == old_zoneno)
                goto got_it;
        if (dir == ALLOC_LEFT) {
                if (!go_left && zoneno + 1 >= total_zones)
                        goto got_it;
                if (go_left && zoneno == 0)
                        goto got_it;
        }
        for (i = 0; i < NR_CURSEG_TYPE; i++)
                if (CURSEG_I(sbi, i)->zone == zoneno)
                        break;

        if (i < NR_CURSEG_TYPE) {
                /* zone is in user, try another */
                if (go_left)
                        hint = zoneno * sbi->secs_per_zone - 1;
                else if (zoneno + 1 >= total_zones)
                        hint = 0;
                else
                        hint = (zoneno + 1) * sbi->secs_per_zone;
                init = false;
                goto find_other_zone;
        }
got_it:
        /* set it as dirty segment in free segmap */
        f2fs_bug_on(sbi, test_bit(segno, free_i->free_segmap));
        __set_inuse(sbi, segno);
        *newseg = segno;
        spin_unlock(&free_i->segmap_lock);
}

static void reset_curseg(struct f2fs_sb_info *sbi, int type, int modified)
{
        struct curseg_info *curseg = CURSEG_I(sbi, type);
        struct summary_footer *sum_footer;

        curseg->segno = curseg->next_segno;
        curseg->zone = GET_ZONENO_FROM_SEGNO(sbi, curseg->segno);
        curseg->next_blkoff = 0;
        curseg->next_segno = NULL_SEGNO;

        sum_footer = &(curseg->sum_blk->footer);
        memset(sum_footer, 0, sizeof(struct summary_footer));
        if (IS_DATASEG(type))
                SET_SUM_TYPE(sum_footer, SUM_TYPE_DATA);
        if (IS_NODESEG(type))
                SET_SUM_TYPE(sum_footer, SUM_TYPE_NODE);
        __set_sit_entry_type(sbi, type, curseg->segno, modified);
}

/*
 * Allocate a current working segment.
 * This function always allocates a free segment in LFS manner.
 */
static void new_curseg(struct f2fs_sb_info *sbi, int type, bool new_sec)
{
        struct curseg_info *curseg = CURSEG_I(sbi, type);
        unsigned int segno = curseg->segno;
        int dir = ALLOC_LEFT;

        write_sum_page(sbi, curseg->sum_blk,
                                GET_SUM_BLOCK(sbi, segno));
        if (type == CURSEG_WARM_DATA || type == CURSEG_COLD_DATA)
                dir = ALLOC_RIGHT;

        if (test_opt(sbi, NOHEAP))
                dir = ALLOC_RIGHT;

        get_new_segment(sbi, &segno, new_sec, dir);
        curseg->next_segno = segno;
        reset_curseg(sbi, type, 1);
        curseg->alloc_type = LFS;
}

static void __next_free_blkoff(struct f2fs_sb_info *sbi,
                        struct curseg_info *seg, block_t start)
{
        struct seg_entry *se = get_seg_entry(sbi, seg->segno);
        int entries = SIT_VBLOCK_MAP_SIZE / sizeof(unsigned long);
        unsigned long *target_map = SIT_I(sbi)->tmp_map;
        unsigned long *ckpt_map = (unsigned long *)se->ckpt_valid_map;
        unsigned long *cur_map = (unsigned long *)se->cur_valid_map;
        int i, pos;

        for (i = 0; i < entries; i++)
                target_map[i] = ckpt_map[i] | cur_map[i];

        pos = __find_rev_next_zero_bit(target_map, sbi->blocks_per_seg, start);

        seg->next_blkoff = pos;
}

/*
 * If a segment is written by LFS manner, next block offset is just obtained
 * by increasing the current block offset. However, if a segment is written by
 * SSR manner, next block offset obtained by calling __next_free_blkoff
 */
static void __refresh_next_blkoff(struct f2fs_sb_info *sbi,
                                struct curseg_info *seg)
{
        if (seg->alloc_type == SSR)
                __next_free_blkoff(sbi, seg, seg->next_blkoff + 1);
        else
                seg->next_blkoff++;
}

/*
 * This function always allocates a used segment(from dirty seglist) by SSR
 * manner, so it should recover the existing segment information of valid blocks
 */
static void change_curseg(struct f2fs_sb_info *sbi, int type, bool reuse)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
        struct curseg_info *curseg = CURSEG_I(sbi, type);
        unsigned int new_segno = curseg->next_segno;
        struct f2fs_summary_block *sum_node;
        struct page *sum_page;

        write_sum_page(sbi, curseg->sum_blk,
                                GET_SUM_BLOCK(sbi, curseg->segno));
        __set_test_and_inuse(sbi, new_segno);

        mutex_lock(&dirty_i->seglist_lock);
        __remove_dirty_segment(sbi, new_segno, PRE);
        __remove_dirty_segment(sbi, new_segno, DIRTY);
        mutex_unlock(&dirty_i->seglist_lock);

        reset_curseg(sbi, type, 1);
        curseg->alloc_type = SSR;
        __next_free_blkoff(sbi, curseg, 0);

        if (reuse) {
                sum_page = get_sum_page(sbi, new_segno);
                sum_node = (struct f2fs_summary_block *)page_address(sum_page);
                memcpy(curseg->sum_blk, sum_node, SUM_ENTRY_SIZE);
                f2fs_put_page(sum_page, 1);
        }
}

static int get_ssr_segment(struct f2fs_sb_info *sbi, int type)
{
        struct curseg_info *curseg = CURSEG_I(sbi, type);
        const struct victim_selection *v_ops = DIRTY_I(sbi)->v_ops;

        if (IS_NODESEG(type) || !has_not_enough_free_secs(sbi, 0, 0))
                return v_ops->get_victim(sbi,
                                &(curseg)->next_segno, BG_GC, type, SSR);

        /* For data segments, let's do SSR more intensively */
        for (; type >= CURSEG_HOT_DATA; type--)
                if (v_ops->get_victim(sbi, &(curseg)->next_segno,
                                                BG_GC, type, SSR))
                        return 1;
        return 0;
}

/*
 * flush out current segment and replace it with new segment
 * This function should be returned with success, otherwise BUG
 */
static void allocate_segment_by_default(struct f2fs_sb_info *sbi,
                                                int type, bool force)
{
        struct curseg_info *curseg = CURSEG_I(sbi, type);

        if (force)
                new_curseg(sbi, type, true);
        else if (type == CURSEG_WARM_NODE)
                new_curseg(sbi, type, false);
        else if (curseg->alloc_type == LFS && is_next_segment_free(sbi, type))
                new_curseg(sbi, type, false);
        else if (need_SSR(sbi) && get_ssr_segment(sbi, type))
                change_curseg(sbi, type, true);
        else
                new_curseg(sbi, type, false);

        stat_inc_seg_type(sbi, curseg);
}

void allocate_new_segments(struct f2fs_sb_info *sbi)
{
        struct curseg_info *curseg;
        unsigned int old_segno;
        int i;

        if (test_opt(sbi, LFS))
                return;

        for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
                curseg = CURSEG_I(sbi, i);
                old_segno = curseg->segno;
                SIT_I(sbi)->s_ops->allocate_segment(sbi, i, true);
                locate_dirty_segment(sbi, old_segno);
        }
}

static const struct segment_allocation default_salloc_ops = {
        .allocate_segment = allocate_segment_by_default,
};

int f2fs_trim_fs(struct f2fs_sb_info *sbi, struct fstrim_range *range)
{
        __u64 start = F2FS_BYTES_TO_BLK(range->start);
        __u64 end = start + F2FS_BYTES_TO_BLK(range->len) - 1;
        unsigned int start_segno, end_segno;
        struct cp_control cpc;
        int err = 0;

        if (start >= MAX_BLKADDR(sbi) || range->len < sbi->blocksize)
                return -EINVAL;

        cpc.trimmed = 0;
        if (end <= MAIN_BLKADDR(sbi))
                goto out;

        if (is_sbi_flag_set(sbi, SBI_NEED_FSCK)) {
                f2fs_msg(sbi->sb, KERN_WARNING,
                        "Found FS corruption, run fsck to fix.");
                goto out;
        }

        /* start/end segment number in main_area */
        start_segno = (start <= MAIN_BLKADDR(sbi)) ? 0 : GET_SEGNO(sbi, start);
        end_segno = (end >= MAX_BLKADDR(sbi)) ? MAIN_SEGS(sbi) - 1 :
                                                GET_SEGNO(sbi, end);
        cpc.reason = CP_DISCARD;
        cpc.trim_minlen = max_t(__u64, 1, F2FS_BYTES_TO_BLK(range->minlen));

        /* do checkpoint to issue discard commands safely */
        for (; start_segno <= end_segno; start_segno = cpc.trim_end + 1) {
                cpc.trim_start = start_segno;

                if (sbi->discard_blks == 0)
                        break;
                else if (sbi->discard_blks < BATCHED_TRIM_BLOCKS(sbi))
                        cpc.trim_end = end_segno;
                else
                        cpc.trim_end = min_t(unsigned int,
                                rounddown(start_segno +
                                BATCHED_TRIM_SEGMENTS(sbi),
                                sbi->segs_per_sec) - 1, end_segno);

                mutex_lock(&sbi->gc_mutex);
                err = write_checkpoint(sbi, &cpc);
                mutex_unlock(&sbi->gc_mutex);
                if (err)
                        break;

                schedule();
        }
out:
        range->len = F2FS_BLK_TO_BYTES(cpc.trimmed);
        return err;
}

static bool __has_curseg_space(struct f2fs_sb_info *sbi, int type)
{
        struct curseg_info *curseg = CURSEG_I(sbi, type);
        if (curseg->next_blkoff < sbi->blocks_per_seg)
                return true;
        return false;
}

static int __get_segment_type_2(struct page *page, enum page_type p_type)
{
        if (p_type == DATA)
                return CURSEG_HOT_DATA;
        else
                return CURSEG_HOT_NODE;
}

static int __get_segment_type_4(struct page *page, enum page_type p_type)
{
        if (p_type == DATA) {
                struct inode *inode = page->mapping->host;

                if (S_ISDIR(inode->i_mode))
                        return CURSEG_HOT_DATA;
                else
                        return CURSEG_COLD_DATA;
        } else {
                if (IS_DNODE(page) && is_cold_node(page))
                        return CURSEG_WARM_NODE;
                else
                        return CURSEG_COLD_NODE;
        }
}

static int __get_segment_type_6(struct page *page, enum page_type p_type)
{
        if (p_type == DATA) {
                struct inode *inode = page->mapping->host;

                if (S_ISDIR(inode->i_mode))
                        return CURSEG_HOT_DATA;
                else if (is_cold_data(page) || file_is_cold(inode))
                        return CURSEG_COLD_DATA;
                else
                        return CURSEG_WARM_DATA;
        } else {
                if (IS_DNODE(page))
                        return is_cold_node(page) ? CURSEG_WARM_NODE :
                                                CURSEG_HOT_NODE;
                else
                        return CURSEG_COLD_NODE;
        }
}

static int __get_segment_type(struct page *page, enum page_type p_type)
{
        switch (F2FS_P_SB(page)->active_logs) {
        case 2:
                return __get_segment_type_2(page, p_type);
        case 4:
                return __get_segment_type_4(page, p_type);
        }
        /* NR_CURSEG_TYPE(6) logs by default */
        f2fs_bug_on(F2FS_P_SB(page),
                F2FS_P_SB(page)->active_logs != NR_CURSEG_TYPE);
        return __get_segment_type_6(page, p_type);
}

void allocate_data_block(struct f2fs_sb_info *sbi, struct page *page,
                block_t old_blkaddr, block_t *new_blkaddr,
                struct f2fs_summary *sum, int type)
{
        struct sit_info *sit_i = SIT_I(sbi);
        struct curseg_info *curseg = CURSEG_I(sbi, type);

        mutex_lock(&curseg->curseg_mutex);
        mutex_lock(&sit_i->sentry_lock);

        *new_blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);

        /*
         * __add_sum_entry should be resided under the curseg_mutex
         * because, this function updates a summary entry in the
         * current summary block.
         */
        __add_sum_entry(sbi, type, sum);

        __refresh_next_blkoff(sbi, curseg);

        stat_inc_block_count(sbi, curseg);

        if (!__has_curseg_space(sbi, type))
                sit_i->s_ops->allocate_segment(sbi, type, false);
        /*
         * SIT information should be updated before segment allocation,
         * since SSR needs latest valid block information.
         */
        refresh_sit_entry(sbi, old_blkaddr, *new_blkaddr);

        mutex_unlock(&sit_i->sentry_lock);

        if (page && IS_NODESEG(type))
                fill_node_footer_blkaddr(page, NEXT_FREE_BLKADDR(sbi, curseg));

        mutex_unlock(&curseg->curseg_mutex);
}

static void do_write_page(struct f2fs_summary *sum, struct f2fs_io_info *fio)
{
        int type = __get_segment_type(fio->page, fio->type);

        if (fio->type == NODE || fio->type == DATA)
                mutex_lock(&fio->sbi->wio_mutex[fio->type]);

        allocate_data_block(fio->sbi, fio->page, fio->old_blkaddr,
                                        &fio->new_blkaddr, sum, type);

        /* writeout dirty page into bdev */
        f2fs_submit_page_mbio(fio);

        if (fio->type == NODE || fio->type == DATA)
                mutex_unlock(&fio->sbi->wio_mutex[fio->type]);
}

void write_meta_page(struct f2fs_sb_info *sbi, struct page *page)
{
        struct f2fs_io_info fio = {
                .sbi = sbi,
                .type = META,
                .op = REQ_OP_WRITE,
                .op_flags = REQ_SYNC | REQ_META | REQ_PRIO,
                .old_blkaddr = page->index,
                .new_blkaddr = page->index,
                .page = page,
                .encrypted_page = NULL,
        };

        if (unlikely(page->index >= MAIN_BLKADDR(sbi)))
                fio.op_flags &= ~REQ_META;

        set_page_writeback(page);
        f2fs_submit_page_mbio(&fio);
}

void write_node_page(unsigned int nid, struct f2fs_io_info *fio)
{
        struct f2fs_summary sum;

        set_summary(&sum, nid, 0, 0);
        do_write_page(&sum, fio);
}

void write_data_page(struct dnode_of_data *dn, struct f2fs_io_info *fio)
{
        struct f2fs_sb_info *sbi = fio->sbi;
        struct f2fs_summary sum;
        struct node_info ni;

        f2fs_bug_on(sbi, dn->data_blkaddr == NULL_ADDR);
        get_node_info(sbi, dn->nid, &ni);
        set_summary(&sum, dn->nid, dn->ofs_in_node, ni.version);
        do_write_page(&sum, fio);
        f2fs_update_data_blkaddr(dn, fio->new_blkaddr);
}

void rewrite_data_page(struct f2fs_io_info *fio)
{
        fio->new_blkaddr = fio->old_blkaddr;
        stat_inc_inplace_blocks(fio->sbi);
        f2fs_submit_page_mbio(fio);
}

void __f2fs_replace_block(struct f2fs_sb_info *sbi, struct f2fs_summary *sum,
                                block_t old_blkaddr, block_t new_blkaddr,
                                bool recover_curseg, bool recover_newaddr)
{
        struct sit_info *sit_i = SIT_I(sbi);
        struct curseg_info *curseg;
        unsigned int segno, old_cursegno;
        struct seg_entry *se;
        int type;
        unsigned short old_blkoff;

        segno = GET_SEGNO(sbi, new_blkaddr);
        se = get_seg_entry(sbi, segno);
        type = se->type;

        if (!recover_curseg) {
                /* for recovery flow */
                if (se->valid_blocks == 0 && !IS_CURSEG(sbi, segno)) {
                        if (old_blkaddr == NULL_ADDR)
                                type = CURSEG_COLD_DATA;
                        else
                                type = CURSEG_WARM_DATA;
                }
        } else {
                if (!IS_CURSEG(sbi, segno))
                        type = CURSEG_WARM_DATA;
        }

        curseg = CURSEG_I(sbi, type);

        mutex_lock(&curseg->curseg_mutex);
        mutex_lock(&sit_i->sentry_lock);

        old_cursegno = curseg->segno;
        old_blkoff = curseg->next_blkoff;

        /* change the current segment */
        if (segno != curseg->segno) {
                curseg->next_segno = segno;
                change_curseg(sbi, type, true);
        }

        curseg->next_blkoff = GET_BLKOFF_FROM_SEG0(sbi, new_blkaddr);
        __add_sum_entry(sbi, type, sum);

        if (!recover_curseg || recover_newaddr)
                update_sit_entry(sbi, new_blkaddr, 1);
        if (GET_SEGNO(sbi, old_blkaddr) != NULL_SEGNO)
                update_sit_entry(sbi, old_blkaddr, -1);

        locate_dirty_segment(sbi, GET_SEGNO(sbi, old_blkaddr));
        locate_dirty_segment(sbi, GET_SEGNO(sbi, new_blkaddr));

        locate_dirty_segment(sbi, old_cursegno);

        if (recover_curseg) {
                if (old_cursegno != curseg->segno) {
                        curseg->next_segno = old_cursegno;
                        change_curseg(sbi, type, true);
                }
                curseg->next_blkoff = old_blkoff;
        }

        mutex_unlock(&sit_i->sentry_lock);
        mutex_unlock(&curseg->curseg_mutex);
}

void f2fs_replace_block(struct f2fs_sb_info *sbi, struct dnode_of_data *dn,
                                block_t old_addr, block_t new_addr,
                                unsigned char version, bool recover_curseg,
                                bool recover_newaddr)
{
        struct f2fs_summary sum;

        set_summary(&sum, dn->nid, dn->ofs_in_node, version);

        __f2fs_replace_block(sbi, &sum, old_addr, new_addr,
                                        recover_curseg, recover_newaddr);

        f2fs_update_data_blkaddr(dn, new_addr);
}

void f2fs_wait_on_page_writeback(struct page *page,
                                enum page_type type, bool ordered)
{
        if (PageWriteback(page)) {
                struct f2fs_sb_info *sbi = F2FS_P_SB(page);

                f2fs_submit_merged_bio_cond(sbi, NULL, page, 0, type, WRITE);
                if (ordered)
                        wait_on_page_writeback(page);
                else
                        wait_for_stable_page(page);
        }
}

void f2fs_wait_on_encrypted_page_writeback(struct f2fs_sb_info *sbi,
                                                        block_t blkaddr)
{
        struct page *cpage;

        if (blkaddr == NEW_ADDR || blkaddr == NULL_ADDR)
                return;

        cpage = find_lock_page(META_MAPPING(sbi), blkaddr);
        if (cpage) {
                f2fs_wait_on_page_writeback(cpage, DATA, true);
                f2fs_put_page(cpage, 1);
        }
}

static int read_compacted_summaries(struct f2fs_sb_info *sbi)
{
        struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
        struct curseg_info *seg_i;
        unsigned char *kaddr;
        struct page *page;
        block_t start;
        int i, j, offset;

        start = start_sum_block(sbi);

        page = get_meta_page(sbi, start++);
        kaddr = (unsigned char *)page_address(page);

        /* Step 1: restore nat cache */
        seg_i = CURSEG_I(sbi, CURSEG_HOT_DATA);
        memcpy(seg_i->journal, kaddr, SUM_JOURNAL_SIZE);

        /* Step 2: restore sit cache */
        seg_i = CURSEG_I(sbi, CURSEG_COLD_DATA);
        memcpy(seg_i->journal, kaddr + SUM_JOURNAL_SIZE, SUM_JOURNAL_SIZE);
        offset = 2 * SUM_JOURNAL_SIZE;

        /* Step 3: restore summary entries */
        for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
                unsigned short blk_off;
                unsigned int segno;

                seg_i = CURSEG_I(sbi, i);
                segno = le32_to_cpu(ckpt->cur_data_segno[i]);
                blk_off = le16_to_cpu(ckpt->cur_data_blkoff[i]);
                seg_i->next_segno = segno;
                reset_curseg(sbi, i, 0);
                seg_i->alloc_type = ckpt->alloc_type[i];
                seg_i->next_blkoff = blk_off;

                if (seg_i->alloc_type == SSR)
                        blk_off = sbi->blocks_per_seg;

                for (j = 0; j < blk_off; j++) {
                        struct f2fs_summary *s;
                        s = (struct f2fs_summary *)(kaddr + offset);
                        seg_i->sum_blk->entries[j] = *s;
                        offset += SUMMARY_SIZE;
                        if (offset + SUMMARY_SIZE <= PAGE_SIZE -
                                                SUM_FOOTER_SIZE)
                                continue;

                        f2fs_put_page(page, 1);
                        page = NULL;

                        page = get_meta_page(sbi, start++);
                        kaddr = (unsigned char *)page_address(page);
                        offset = 0;
                }
        }
        f2fs_put_page(page, 1);
        return 0;
}

static int read_normal_summaries(struct f2fs_sb_info *sbi, int type)
{
        struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
        struct f2fs_summary_block *sum;
        struct curseg_info *curseg;
        struct page *new;
        unsigned short blk_off;
        unsigned int segno = 0;
        block_t blk_addr = 0;

        /* get segment number and block addr */
        if (IS_DATASEG(type)) {
                segno = le32_to_cpu(ckpt->cur_data_segno[type]);
                blk_off = le16_to_cpu(ckpt->cur_data_blkoff[type -
                                                        CURSEG_HOT_DATA]);
                if (__exist_node_summaries(sbi))
                        blk_addr = sum_blk_addr(sbi, NR_CURSEG_TYPE, type);
                else
                        blk_addr = sum_blk_addr(sbi, NR_CURSEG_DATA_TYPE, type);
        } else {
                segno = le32_to_cpu(ckpt->cur_node_segno[type -
                                                        CURSEG_HOT_NODE]);
                blk_off = le16_to_cpu(ckpt->cur_node_blkoff[type -
                                                        CURSEG_HOT_NODE]);
                if (__exist_node_summaries(sbi))
                        blk_addr = sum_blk_addr(sbi, NR_CURSEG_NODE_TYPE,
                                                        type - CURSEG_HOT_NODE);
                else
                        blk_addr = GET_SUM_BLOCK(sbi, segno);
        }

        new = get_meta_page(sbi, blk_addr);
        sum = (struct f2fs_summary_block *)page_address(new);

        if (IS_NODESEG(type)) {
                if (__exist_node_summaries(sbi)) {
                        struct f2fs_summary *ns = &sum->entries[0];
                        int i;
                        for (i = 0; i < sbi->blocks_per_seg; i++, ns++) {
                                ns->version = 0;
                                ns->ofs_in_node = 0;
                        }
                } else {
                        int err;

                        err = restore_node_summary(sbi, segno, sum);
                        if (err) {
                                f2fs_put_page(new, 1);
                                return err;
                        }
                }
        }

        /* set uncompleted segment to curseg */
        curseg = CURSEG_I(sbi, type);
        mutex_lock(&curseg->curseg_mutex);

        /* update journal info */
        down_write(&curseg->journal_rwsem);
        memcpy(curseg->journal, &sum->journal, SUM_JOURNAL_SIZE);
        up_write(&curseg->journal_rwsem);

        memcpy(curseg->sum_blk->entries, sum->entries, SUM_ENTRY_SIZE);
        memcpy(&curseg->sum_blk->footer, &sum->footer, SUM_FOOTER_SIZE);
        curseg->next_segno = segno;
        reset_curseg(sbi, type, 0);
        curseg->alloc_type = ckpt->alloc_type[type];
        curseg->next_blkoff = blk_off;
        mutex_unlock(&curseg->curseg_mutex);
        f2fs_put_page(new, 1);
        return 0;
}

static int restore_curseg_summaries(struct f2fs_sb_info *sbi)
{
        int type = CURSEG_HOT_DATA;
        int err;

        if (is_set_ckpt_flags(sbi, CP_COMPACT_SUM_FLAG)) {
                int npages = npages_for_summary_flush(sbi, true);

                if (npages >= 2)
                        ra_meta_pages(sbi, start_sum_block(sbi), npages,
                                                        META_CP, true);

                /* restore for compacted data summary */
                if (read_compacted_summaries(sbi))
                        return -EINVAL;
                type = CURSEG_HOT_NODE;
        }

        if (__exist_node_summaries(sbi))
                ra_meta_pages(sbi, sum_blk_addr(sbi, NR_CURSEG_TYPE, type),
                                        NR_CURSEG_TYPE - type, META_CP, true);

        for (; type <= CURSEG_COLD_NODE; type++) {
                err = read_normal_summaries(sbi, type);
                if (err)
                        return err;
        }

        return 0;
}

static void write_compacted_summaries(struct f2fs_sb_info *sbi, block_t blkaddr)
{
        struct page *page;
        unsigned char *kaddr;
        struct f2fs_summary *summary;
        struct curseg_info *seg_i;
        int written_size = 0;
        int i, j;

        page = grab_meta_page(sbi, blkaddr++);
        kaddr = (unsigned char *)page_address(page);

        /* Step 1: write nat cache */
        seg_i = CURSEG_I(sbi, CURSEG_HOT_DATA);
        memcpy(kaddr, seg_i->journal, SUM_JOURNAL_SIZE);
        written_size += SUM_JOURNAL_SIZE;

        /* Step 2: write sit cache */
        seg_i = CURSEG_I(sbi, CURSEG_COLD_DATA);
        memcpy(kaddr + written_size, seg_i->journal, SUM_JOURNAL_SIZE);
        written_size += SUM_JOURNAL_SIZE;

        /* Step 3: write summary entries */
        for (i = CURSEG_HOT_DATA; i <= CURSEG_COLD_DATA; i++) {
                unsigned short blkoff;
                seg_i = CURSEG_I(sbi, i);
                if (sbi->ckpt->alloc_type[i] == SSR)
                        blkoff = sbi->blocks_per_seg;
                else
                        blkoff = curseg_blkoff(sbi, i);

                for (j = 0; j < blkoff; j++) {
                        if (!page) {
                                page = grab_meta_page(sbi, blkaddr++);
                                kaddr = (unsigned char *)page_address(page);
                                written_size = 0;
                        }
                        summary = (struct f2fs_summary *)(kaddr + written_size);
                        *summary = seg_i->sum_blk->entries[j];
                        written_size += SUMMARY_SIZE;

                        if (written_size + SUMMARY_SIZE <= PAGE_SIZE -
                                                        SUM_FOOTER_SIZE)
                                continue;

                        set_page_dirty(page);
                        f2fs_put_page(page, 1);
                        page = NULL;
                }
        }
        if (page) {
                set_page_dirty(page);
                f2fs_put_page(page, 1);
        }
}

static void write_normal_summaries(struct f2fs_sb_info *sbi,
                                        block_t blkaddr, int type)

{
        int i, end;
        if (IS_DATASEG(type))
                end = type + NR_CURSEG_DATA_TYPE;
        else
                end = type + NR_CURSEG_NODE_TYPE;

        for (i = type; i < end; i++)
                write_current_sum_page(sbi, i, blkaddr + (i - type));
}

void write_data_summaries(struct f2fs_sb_info *sbi, block_t start_blk)
{
        if (is_set_ckpt_flags(sbi, CP_COMPACT_SUM_FLAG))
                write_compacted_summaries(sbi, start_blk);
        else
                write_normal_summaries(sbi, start_blk, CURSEG_HOT_DATA);
}

void write_node_summaries(struct f2fs_sb_info *sbi, block_t start_blk)
{
        write_normal_summaries(sbi, start_blk, CURSEG_HOT_NODE);
}

int lookup_journal_in_cursum(struct f2fs_journal *journal, int type,
                                        unsigned int val, int alloc)
{
        int i;

        if (type == NAT_JOURNAL) {
                for (i = 0; i < nats_in_cursum(journal); i++) {
                        if (le32_to_cpu(nid_in_journal(journal, i)) == val)
                                return i;
                }
                if (alloc && __has_cursum_space(journal, 1, NAT_JOURNAL))
                        return update_nats_in_cursum(journal, 1);
        } else if (type == SIT_JOURNAL) {
                for (i = 0; i < sits_in_cursum(journal); i++)
                        if (le32_to_cpu(segno_in_journal(journal, i)) == val)
                                return i;
                if (alloc && __has_cursum_space(journal, 1, SIT_JOURNAL))
                        return update_sits_in_cursum(journal, 1);
        }
        return -1;
}

static struct page *get_current_sit_page(struct f2fs_sb_info *sbi,
                                        unsigned int segno)
{
        return get_meta_page(sbi, current_sit_addr(sbi, segno));
}

static struct page *get_next_sit_page(struct f2fs_sb_info *sbi,
                                        unsigned int start)
{
        struct sit_info *sit_i = SIT_I(sbi);
        struct page *src_page, *dst_page;
        pgoff_t src_off, dst_off;
        void *src_addr, *dst_addr;

        src_off = current_sit_addr(sbi, start);
        dst_off = next_sit_addr(sbi, src_off);

        /* get current sit block page without lock */
        src_page = get_meta_page(sbi, src_off);
        dst_page = grab_meta_page(sbi, dst_off);
        f2fs_bug_on(sbi, PageDirty(src_page));

        src_addr = page_address(src_page);
        dst_addr = page_address(dst_page);
        memcpy(dst_addr, src_addr, PAGE_SIZE);

        set_page_dirty(dst_page);
        f2fs_put_page(src_page, 1);

        set_to_next_sit(sit_i, start);

        return dst_page;
}

static struct sit_entry_set *grab_sit_entry_set(void)
{
        struct sit_entry_set *ses =
                        f2fs_kmem_cache_alloc(sit_entry_set_slab, GFP_NOFS);

        ses->entry_cnt = 0;
        INIT_LIST_HEAD(&ses->set_list);
        return ses;
}

static void release_sit_entry_set(struct sit_entry_set *ses)
{
        list_del(&ses->set_list);
        kmem_cache_free(sit_entry_set_slab, ses);
}

static void adjust_sit_entry_set(struct sit_entry_set *ses,
                                                struct list_head *head)
{
        struct sit_entry_set *next = ses;

        if (list_is_last(&ses->set_list, head))
                return;

        list_for_each_entry_continue(next, head, set_list)
                if (ses->entry_cnt <= next->entry_cnt)
                        break;

        list_move_tail(&ses->set_list, &next->set_list);
}

static void add_sit_entry(unsigned int segno, struct list_head *head)
{
        struct sit_entry_set *ses;
        unsigned int start_segno = START_SEGNO(segno);

        list_for_each_entry(ses, head, set_list) {
                if (ses->start_segno == start_segno) {
                        ses->entry_cnt++;
                        adjust_sit_entry_set(ses, head);
                        return;
                }
        }

        ses = grab_sit_entry_set();

        ses->start_segno = start_segno;
        ses->entry_cnt++;
        list_add(&ses->set_list, head);
}

static void add_sits_in_set(struct f2fs_sb_info *sbi)
{
        struct f2fs_sm_info *sm_info = SM_I(sbi);
        struct list_head *set_list = &sm_info->sit_entry_set;
        unsigned long *bitmap = SIT_I(sbi)->dirty_sentries_bitmap;
        unsigned int segno;

        for_each_set_bit(segno, bitmap, MAIN_SEGS(sbi))
                add_sit_entry(segno, set_list);
}

static void remove_sits_in_journal(struct f2fs_sb_info *sbi)
{
        struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
        struct f2fs_journal *journal = curseg->journal;
        int i;

        down_write(&curseg->journal_rwsem);
        for (i = 0; i < sits_in_cursum(journal); i++) {
                unsigned int segno;
                bool dirtied;

                segno = le32_to_cpu(segno_in_journal(journal, i));
                dirtied = __mark_sit_entry_dirty(sbi, segno);

                if (!dirtied)
                        add_sit_entry(segno, &SM_I(sbi)->sit_entry_set);
        }
        update_sits_in_cursum(journal, -i);
        up_write(&curseg->journal_rwsem);
}

/*
 * CP calls this function, which flushes SIT entries including sit_journal,
 * and moves prefree segs to free segs.
 */
void flush_sit_entries(struct f2fs_sb_info *sbi, struct cp_control *cpc)
{
        struct sit_info *sit_i = SIT_I(sbi);
        unsigned long *bitmap = sit_i->dirty_sentries_bitmap;
        struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
        struct f2fs_journal *journal = curseg->journal;
        struct sit_entry_set *ses, *tmp;
        struct list_head *head = &SM_I(sbi)->sit_entry_set;
        bool to_journal = true;
        struct seg_entry *se;

        mutex_lock(&sit_i->sentry_lock);

        if (!sit_i->dirty_sentries)
                goto out;

        /*
         * add and account sit entries of dirty bitmap in sit entry
         * set temporarily
         */
        add_sits_in_set(sbi);

        /*
         * if there are no enough space in journal to store dirty sit
         * entries, remove all entries from journal and add and account
         * them in sit entry set.
         */
        if (!__has_cursum_space(journal, sit_i->dirty_sentries, SIT_JOURNAL))
                remove_sits_in_journal(sbi);

        /*
         * there are two steps to flush sit entries:
         * #1, flush sit entries to journal in current cold data summary block.
         * #2, flush sit entries to sit page.
         */
        list_for_each_entry_safe(ses, tmp, head, set_list) {
                struct page *page = NULL;
                struct f2fs_sit_block *raw_sit = NULL;
                unsigned int start_segno = ses->start_segno;
                unsigned int end = min(start_segno + SIT_ENTRY_PER_BLOCK,
                                                (unsigned long)MAIN_SEGS(sbi));
                unsigned int segno = start_segno;

                if (to_journal &&
                        !__has_cursum_space(journal, ses->entry_cnt, SIT_JOURNAL))
                        to_journal = false;

                if (to_journal) {
                        down_write(&curseg->journal_rwsem);
                } else {
                        page = get_next_sit_page(sbi, start_segno);
                        raw_sit = page_address(page);
                }

                /* flush dirty sit entries in region of current sit set */
                for_each_set_bit_from(segno, bitmap, end) {
                        int offset, sit_offset;

                        se = get_seg_entry(sbi, segno);

                        /* add discard candidates */
                        if (cpc->reason != CP_DISCARD) {
                                cpc->trim_start = segno;
                                add_discard_addrs(sbi, cpc);
                        }

                        if (to_journal) {
                                offset = lookup_journal_in_cursum(journal,
                                                        SIT_JOURNAL, segno, 1);
                                f2fs_bug_on(sbi, offset < 0);
                                segno_in_journal(journal, offset) =
                                                        cpu_to_le32(segno);
                                seg_info_to_raw_sit(se,
                                        &sit_in_journal(journal, offset));
                        } else {
                                sit_offset = SIT_ENTRY_OFFSET(sit_i, segno);
                                seg_info_to_raw_sit(se,
                                                &raw_sit->entries[sit_offset]);
                        }

                        __clear_bit(segno, bitmap);
                        sit_i->dirty_sentries--;
                        ses->entry_cnt--;
                }

                if (to_journal)
                        up_write(&curseg->journal_rwsem);
                else
                        f2fs_put_page(page, 1);

                f2fs_bug_on(sbi, ses->entry_cnt);
                release_sit_entry_set(ses);
        }

        f2fs_bug_on(sbi, !list_empty(head));
        f2fs_bug_on(sbi, sit_i->dirty_sentries);
out:
        if (cpc->reason == CP_DISCARD) {
                for (; cpc->trim_start <= cpc->trim_end; cpc->trim_start++)
                        add_discard_addrs(sbi, cpc);
        }
        mutex_unlock(&sit_i->sentry_lock);

        set_prefree_as_free_segments(sbi);
}

static int build_sit_info(struct f2fs_sb_info *sbi)
{
        struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
        struct sit_info *sit_i;
        unsigned int sit_segs, start;
        char *src_bitmap, *dst_bitmap;
        unsigned int bitmap_size;

        /* allocate memory for SIT information */
        sit_i = kzalloc(sizeof(struct sit_info), GFP_KERNEL);
        if (!sit_i)
                return -ENOMEM;

        SM_I(sbi)->sit_info = sit_i;

        sit_i->sentries = f2fs_kvzalloc(MAIN_SEGS(sbi) *
                                        sizeof(struct seg_entry), GFP_KERNEL);
        if (!sit_i->sentries)
                return -ENOMEM;

        bitmap_size = f2fs_bitmap_size(MAIN_SEGS(sbi));
        sit_i->dirty_sentries_bitmap = f2fs_kvzalloc(bitmap_size, GFP_KERNEL);
        if (!sit_i->dirty_sentries_bitmap)
                return -ENOMEM;

        for (start = 0; start < MAIN_SEGS(sbi); start++) {
                sit_i->sentries[start].cur_valid_map
                        = kzalloc(SIT_VBLOCK_MAP_SIZE, GFP_KERNEL);
                sit_i->sentries[start].ckpt_valid_map
                        = kzalloc(SIT_VBLOCK_MAP_SIZE, GFP_KERNEL);
                if (!sit_i->sentries[start].cur_valid_map ||
                                !sit_i->sentries[start].ckpt_valid_map)
                        return -ENOMEM;

                if (f2fs_discard_en(sbi)) {
                        sit_i->sentries[start].discard_map
                                = kzalloc(SIT_VBLOCK_MAP_SIZE, GFP_KERNEL);
                        if (!sit_i->sentries[start].discard_map)
                                return -ENOMEM;
                }
        }

        sit_i->tmp_map = kzalloc(SIT_VBLOCK_MAP_SIZE, GFP_KERNEL);
        if (!sit_i->tmp_map)
                return -ENOMEM;

        if (sbi->segs_per_sec > 1) {
                sit_i->sec_entries = f2fs_kvzalloc(MAIN_SECS(sbi) *
                                        sizeof(struct sec_entry), GFP_KERNEL);
                if (!sit_i->sec_entries)
                        return -ENOMEM;
        }

        /* get information related with SIT */
        sit_segs = le32_to_cpu(raw_super->segment_count_sit) >> 1;

        /* setup SIT bitmap from ckeckpoint pack */
        bitmap_size = __bitmap_size(sbi, SIT_BITMAP);
        src_bitmap = __bitmap_ptr(sbi, SIT_BITMAP);

        dst_bitmap = kmemdup(src_bitmap, bitmap_size, GFP_KERNEL);
        if (!dst_bitmap)
                return -ENOMEM;

        /* init SIT information */
        sit_i->s_ops = &default_salloc_ops;

        sit_i->sit_base_addr = le32_to_cpu(raw_super->sit_blkaddr);
        sit_i->sit_blocks = sit_segs << sbi->log_blocks_per_seg;
        sit_i->written_valid_blocks = 0;
        sit_i->sit_bitmap = dst_bitmap;
        sit_i->bitmap_size = bitmap_size;
        sit_i->dirty_sentries = 0;
        sit_i->sents_per_block = SIT_ENTRY_PER_BLOCK;
        sit_i->elapsed_time = le64_to_cpu(sbi->ckpt->elapsed_time);
        sit_i->mounted_time = CURRENT_TIME_SEC.tv_sec;
        mutex_init(&sit_i->sentry_lock);
        return 0;
}

static int build_free_segmap(struct f2fs_sb_info *sbi)
{
        struct free_segmap_info *free_i;
        unsigned int bitmap_size, sec_bitmap_size;

        /* allocate memory for free segmap information */
        free_i = kzalloc(sizeof(struct free_segmap_info), GFP_KERNEL);
        if (!free_i)
                return -ENOMEM;

        SM_I(sbi)->free_info = free_i;

        bitmap_size = f2fs_bitmap_size(MAIN_SEGS(sbi));
        free_i->free_segmap = f2fs_kvmalloc(bitmap_size, GFP_KERNEL);
        if (!free_i->free_segmap)
                return -ENOMEM;

        sec_bitmap_size = f2fs_bitmap_size(MAIN_SECS(sbi));
        free_i->free_secmap = f2fs_kvmalloc(sec_bitmap_size, GFP_KERNEL);
        if (!free_i->free_secmap)
                return -ENOMEM;

        /* set all segments as dirty temporarily */
        memset(free_i->free_segmap, 0xff, bitmap_size);
        memset(free_i->free_secmap, 0xff, sec_bitmap_size);

        /* init free segmap information */
        free_i->start_segno = GET_SEGNO_FROM_SEG0(sbi, MAIN_BLKADDR(sbi));
        free_i->free_segments = 0;
        free_i->free_sections = 0;
        spin_lock_init(&free_i->segmap_lock);
        return 0;
}

static int build_curseg(struct f2fs_sb_info *sbi)
{
        struct curseg_info *array;
        int i;

        array = kcalloc(NR_CURSEG_TYPE, sizeof(*array), GFP_KERNEL);
        if (!array)
                return -ENOMEM;

        SM_I(sbi)->curseg_array = array;

        for (i = 0; i < NR_CURSEG_TYPE; i++) {
                mutex_init(&array[i].curseg_mutex);
                array[i].sum_blk = kzalloc(PAGE_SIZE, GFP_KERNEL);
                if (!array[i].sum_blk)
                        return -ENOMEM;
                init_rwsem(&array[i].journal_rwsem);
                array[i].journal = kzalloc(sizeof(struct f2fs_journal),
                                                        GFP_KERNEL);
                if (!array[i].journal)
                        return -ENOMEM;
                array[i].segno = NULL_SEGNO;
                array[i].next_blkoff = 0;
        }
        return restore_curseg_summaries(sbi);
}

static void build_sit_entries(struct f2fs_sb_info *sbi)
{
        struct sit_info *sit_i = SIT_I(sbi);
        struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_COLD_DATA);
        struct f2fs_journal *journal = curseg->journal;
        struct seg_entry *se;
        struct f2fs_sit_entry sit;
        int sit_blk_cnt = SIT_BLK_CNT(sbi);
        unsigned int i, start, end;
        unsigned int readed, start_blk = 0;

        do {
                readed = ra_meta_pages(sbi, start_blk, BIO_MAX_PAGES,
                                                        META_SIT, true);

                start = start_blk * sit_i->sents_per_block;
                end = (start_blk + readed) * sit_i->sents_per_block;

                for (; start < end && start < MAIN_SEGS(sbi); start++) {
                        struct f2fs_sit_block *sit_blk;
                        struct page *page;

                        se = &sit_i->sentries[start];
                        page = get_current_sit_page(sbi, start);
                        sit_blk = (struct f2fs_sit_block *)page_address(page);
                        sit = sit_blk->entries[SIT_ENTRY_OFFSET(sit_i, start)];
                        f2fs_put_page(page, 1);

                        check_block_count(sbi, start, &sit);
                        seg_info_from_raw_sit(se, &sit);

                        /* build discard map only one time */
                        if (f2fs_discard_en(sbi)) {
                                memcpy(se->discard_map, se->cur_valid_map,
                                                        SIT_VBLOCK_MAP_SIZE);
                                sbi->discard_blks += sbi->blocks_per_seg -
                                                        se->valid_blocks;
                        }

                        if (sbi->segs_per_sec > 1)
                                get_sec_entry(sbi, start)->valid_blocks +=
                                                        se->valid_blocks;
                }
                start_blk += readed;
        } while (start_blk < sit_blk_cnt);

        down_read(&curseg->journal_rwsem);
        for (i = 0; i < sits_in_cursum(journal); i++) {
                unsigned int old_valid_blocks;

                start = le32_to_cpu(segno_in_journal(journal, i));
                se = &sit_i->sentries[start];
                sit = sit_in_journal(journal, i);

                old_valid_blocks = se->valid_blocks;

                check_block_count(sbi, start, &sit);
                seg_info_from_raw_sit(se, &sit);

                if (f2fs_discard_en(sbi)) {
                        memcpy(se->discard_map, se->cur_valid_map,
                                                SIT_VBLOCK_MAP_SIZE);
                        sbi->discard_blks += old_valid_blocks -
                                                se->valid_blocks;
                }

                if (sbi->segs_per_sec > 1)
                        get_sec_entry(sbi, start)->valid_blocks +=
                                se->valid_blocks - old_valid_blocks;
        }
        up_read(&curseg->journal_rwsem);
}

static void init_free_segmap(struct f2fs_sb_info *sbi)
{
        unsigned int start;
        int type;

        for (start = 0; start < MAIN_SEGS(sbi); start++) {
                struct seg_entry *sentry = get_seg_entry(sbi, start);
                if (!sentry->valid_blocks)
                        __set_free(sbi, start);
                else
                        SIT_I(sbi)->written_valid_blocks +=
                                                sentry->valid_blocks;
        }

        /* set use the current segments */
        for (type = CURSEG_HOT_DATA; type <= CURSEG_COLD_NODE; type++) {
                struct curseg_info *curseg_t = CURSEG_I(sbi, type);
                __set_test_and_inuse(sbi, curseg_t->segno);
        }
}

static void init_dirty_segmap(struct f2fs_sb_info *sbi)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
        struct free_segmap_info *free_i = FREE_I(sbi);
        unsigned int segno = 0, offset = 0;
        unsigned short valid_blocks;

        while (1) {
                /* find dirty segment based on free segmap */
                segno = find_next_inuse(free_i, MAIN_SEGS(sbi), offset);
                if (segno >= MAIN_SEGS(sbi))
                        break;
                offset = segno + 1;
                valid_blocks = get_valid_blocks(sbi, segno, 0);
                if (valid_blocks == sbi->blocks_per_seg || !valid_blocks)
                        continue;
                if (valid_blocks > sbi->blocks_per_seg) {
                        f2fs_bug_on(sbi, 1);
                        continue;
                }
                mutex_lock(&dirty_i->seglist_lock);
                __locate_dirty_segment(sbi, segno, DIRTY);
                mutex_unlock(&dirty_i->seglist_lock);
        }
}

static int init_victim_secmap(struct f2fs_sb_info *sbi)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
        unsigned int bitmap_size = f2fs_bitmap_size(MAIN_SECS(sbi));

        dirty_i->victim_secmap = f2fs_kvzalloc(bitmap_size, GFP_KERNEL);
        if (!dirty_i->victim_secmap)
                return -ENOMEM;
        return 0;
}

static int build_dirty_segmap(struct f2fs_sb_info *sbi)
{
        struct dirty_seglist_info *dirty_i;
        unsigned int bitmap_size, i;

        /* allocate memory for dirty segments list information */
        dirty_i = kzalloc(sizeof(struct dirty_seglist_info), GFP_KERNEL);
        if (!dirty_i)
                return -ENOMEM;

        SM_I(sbi)->dirty_info = dirty_i;
        mutex_init(&dirty_i->seglist_lock);

        bitmap_size = f2fs_bitmap_size(MAIN_SEGS(sbi));

        for (i = 0; i < NR_DIRTY_TYPE; i++) {
                dirty_i->dirty_segmap[i] = f2fs_kvzalloc(bitmap_size, GFP_KERNEL);
                if (!dirty_i->dirty_segmap[i])
                        return -ENOMEM;
        }

        init_dirty_segmap(sbi);
        return init_victim_secmap(sbi);
}

/*
 * Update min, max modified time for cost-benefit GC algorithm
 */
static void init_min_max_mtime(struct f2fs_sb_info *sbi)
{
        struct sit_info *sit_i = SIT_I(sbi);
        unsigned int segno;

        mutex_lock(&sit_i->sentry_lock);

        sit_i->min_mtime = LLONG_MAX;

        for (segno = 0; segno < MAIN_SEGS(sbi); segno += sbi->segs_per_sec) {
                unsigned int i;
                unsigned long long mtime = 0;

                for (i = 0; i < sbi->segs_per_sec; i++)
                        mtime += get_seg_entry(sbi, segno + i)->mtime;

                mtime = div_u64(mtime, sbi->segs_per_sec);

                if (sit_i->min_mtime > mtime)
                        sit_i->min_mtime = mtime;
        }
        sit_i->max_mtime = get_mtime(sbi);
        mutex_unlock(&sit_i->sentry_lock);
}

int build_segment_manager(struct f2fs_sb_info *sbi)
{
        struct f2fs_super_block *raw_super = F2FS_RAW_SUPER(sbi);
        struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
        struct f2fs_sm_info *sm_info;
        int err;

        sm_info = kzalloc(sizeof(struct f2fs_sm_info), GFP_KERNEL);
        if (!sm_info)
                return -ENOMEM;

        /* init sm info */
        sbi->sm_info = sm_info;
        sm_info->seg0_blkaddr = le32_to_cpu(raw_super->segment0_blkaddr);
        sm_info->main_blkaddr = le32_to_cpu(raw_super->main_blkaddr);
        sm_info->segment_count = le32_to_cpu(raw_super->segment_count);
        sm_info->reserved_segments = le32_to_cpu(ckpt->rsvd_segment_count);
        sm_info->ovp_segments = le32_to_cpu(ckpt->overprov_segment_count);
        sm_info->main_segments = le32_to_cpu(raw_super->segment_count_main);
        sm_info->ssa_blkaddr = le32_to_cpu(raw_super->ssa_blkaddr);
        sm_info->rec_prefree_segments = sm_info->main_segments *
                                        DEF_RECLAIM_PREFREE_SEGMENTS / 100;
        if (sm_info->rec_prefree_segments > DEF_MAX_RECLAIM_PREFREE_SEGMENTS)
                sm_info->rec_prefree_segments = DEF_MAX_RECLAIM_PREFREE_SEGMENTS;

        if (!test_opt(sbi, LFS))
                sm_info->ipu_policy = 1 << F2FS_IPU_FSYNC;
        sm_info->min_ipu_util = DEF_MIN_IPU_UTIL;
        sm_info->min_fsync_blocks = DEF_MIN_FSYNC_BLOCKS;

        INIT_LIST_HEAD(&sm_info->discard_list);
        INIT_LIST_HEAD(&sm_info->wait_list);
        sm_info->nr_discards = 0;
        sm_info->max_discards = 0;

        sm_info->trim_sections = DEF_BATCHED_TRIM_SECTIONS;

        INIT_LIST_HEAD(&sm_info->sit_entry_set);

        if (test_opt(sbi, FLUSH_MERGE) && !f2fs_readonly(sbi->sb)) {
                err = create_flush_cmd_control(sbi);
                if (err)
                        return err;
        }

        err = build_sit_info(sbi);
        if (err)
                return err;
        err = build_free_segmap(sbi);
        if (err)
                return err;
        err = build_curseg(sbi);
        if (err)
                return err;

        /* reinit free segmap based on SIT */
        build_sit_entries(sbi);

        init_free_segmap(sbi);
        err = build_dirty_segmap(sbi);
        if (err)
                return err;

        init_min_max_mtime(sbi);
        return 0;
}

static void discard_dirty_segmap(struct f2fs_sb_info *sbi,
                enum dirty_type dirty_type)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);

        mutex_lock(&dirty_i->seglist_lock);
        kvfree(dirty_i->dirty_segmap[dirty_type]);
        dirty_i->nr_dirty[dirty_type] = 0;
        mutex_unlock(&dirty_i->seglist_lock);
}

static void destroy_victim_secmap(struct f2fs_sb_info *sbi)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
        kvfree(dirty_i->victim_secmap);
}

static void destroy_dirty_segmap(struct f2fs_sb_info *sbi)
{
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
        int i;

        if (!dirty_i)
                return;

        /* discard pre-free/dirty segments list */
        for (i = 0; i < NR_DIRTY_TYPE; i++)
                discard_dirty_segmap(sbi, i);

        destroy_victim_secmap(sbi);
        SM_I(sbi)->dirty_info = NULL;
        kfree(dirty_i);
}

static void destroy_curseg(struct f2fs_sb_info *sbi)
{
        struct curseg_info *array = SM_I(sbi)->curseg_array;
        int i;

        if (!array)
                return;
        SM_I(sbi)->curseg_array = NULL;
        for (i = 0; i < NR_CURSEG_TYPE; i++) {
                kfree(array[i].sum_blk);
                kfree(array[i].journal);
        }
        kfree(array);
}

static void destroy_free_segmap(struct f2fs_sb_info *sbi)
{
        struct free_segmap_info *free_i = SM_I(sbi)->free_info;
        if (!free_i)
                return;
        SM_I(sbi)->free_info = NULL;
        kvfree(free_i->free_segmap);
        kvfree(free_i->free_secmap);
        kfree(free_i);
}

static void destroy_sit_info(struct f2fs_sb_info *sbi)
{
        struct sit_info *sit_i = SIT_I(sbi);
        unsigned int start;

        if (!sit_i)
                return;

        if (sit_i->sentries) {
                for (start = 0; start < MAIN_SEGS(sbi); start++) {
                        kfree(sit_i->sentries[start].cur_valid_map);
                        kfree(sit_i->sentries[start].ckpt_valid_map);
                        kfree(sit_i->sentries[start].discard_map);
                }
        }
        kfree(sit_i->tmp_map);

        kvfree(sit_i->sentries);
        kvfree(sit_i->sec_entries);
        kvfree(sit_i->dirty_sentries_bitmap);

        SM_I(sbi)->sit_info = NULL;
        kfree(sit_i->sit_bitmap);
        kfree(sit_i);
}

void destroy_segment_manager(struct f2fs_sb_info *sbi)
{
        struct f2fs_sm_info *sm_info = SM_I(sbi);

        if (!sm_info)
                return;
        destroy_flush_cmd_control(sbi, true);
        destroy_dirty_segmap(sbi);
        destroy_curseg(sbi);
        destroy_free_segmap(sbi);
        destroy_sit_info(sbi);
        sbi->sm_info = NULL;
        kfree(sm_info);
}

int __init create_segment_manager_caches(void)
{
        discard_entry_slab = f2fs_kmem_cache_create("discard_entry",
                        sizeof(struct discard_entry));
        if (!discard_entry_slab)
                goto fail;

        bio_entry_slab = f2fs_kmem_cache_create("bio_entry",
                        sizeof(struct bio_entry));
        if (!bio_entry_slab)
                goto destroy_discard_entry;

        sit_entry_set_slab = f2fs_kmem_cache_create("sit_entry_set",
                        sizeof(struct sit_entry_set));
        if (!sit_entry_set_slab)
                goto destroy_bio_entry;

        inmem_entry_slab = f2fs_kmem_cache_create("inmem_page_entry",
                        sizeof(struct inmem_pages));
        if (!inmem_entry_slab)
                goto destroy_sit_entry_set;
        return 0;

destroy_sit_entry_set:
        kmem_cache_destroy(sit_entry_set_slab);
destroy_bio_entry:
        kmem_cache_destroy(bio_entry_slab);
destroy_discard_entry:
        kmem_cache_destroy(discard_entry_slab);
fail:
        return -ENOMEM;
}

void destroy_segment_manager_caches(void)
{
        kmem_cache_destroy(sit_entry_set_slab);
        kmem_cache_destroy(bio_entry_slab);
        kmem_cache_destroy(discard_entry_slab);
        kmem_cache_destroy(inmem_entry_slab);
}