/*
 * 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 <linux/freezer.h>
#include <linux/sched/signal.h>

#include "f2fs.h"
#include "segment.h"
#include "node.h"
#include "gc.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 *discard_cmd_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);
}

bool f2fs_need_SSR(struct f2fs_sb_info *sbi)
{
        int node_secs = get_blocktype_secs(sbi, F2FS_DIRTY_NODES);
        int dent_secs = get_blocktype_secs(sbi, F2FS_DIRTY_DENTS);
        int imeta_secs = get_blocktype_secs(sbi, F2FS_DIRTY_IMETA);

        if (test_opt(sbi, LFS))
                return false;
        if (sbi->gc_mode == GC_URGENT)
                return true;

        return free_sections(sbi) <= (node_secs + 2 * dent_secs + imeta_secs +
                        SM_I(sbi)->min_ssr_sections + reserved_sections(sbi));
}

void f2fs_register_inmem_page(struct inode *inode, struct page *page)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        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);
        spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
        if (list_empty(&fi->inmem_ilist))
                list_add_tail(&fi->inmem_ilist, &sbi->inode_list[ATOMIC_FILE]);
        spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
        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);

                f2fs_wait_on_page_writeback(page, DATA, true);

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

                        trace_f2fs_commit_inmem_page(page, INMEM_REVOKE);
retry:
                        set_new_dnode(&dn, inode, NULL, NULL, 0);
                        err = f2fs_get_dnode_of_data(&dn, page->index,
                                                                LOOKUP_NODE);
                        if (err) {
                                if (err == -ENOMEM) {
                                        congestion_wait(BLK_RW_ASYNC, HZ/50);
                                        cond_resched();
                                        goto retry;
                                }
                                err = -EAGAIN;
                                goto next;
                        }

                        err = f2fs_get_node_info(sbi, dn.nid, &ni);
                        if (err) {
                                f2fs_put_dnode(&dn);
                                return err;
                        }

                        if (cur->old_addr == NEW_ADDR) {
                                f2fs_invalidate_blocks(sbi, dn.data_blkaddr);
                                f2fs_update_data_blkaddr(&dn, NEW_ADDR);
                        } else
                                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 f2fs_drop_inmem_pages_all(struct f2fs_sb_info *sbi, bool gc_failure)
{
        struct list_head *head = &sbi->inode_list[ATOMIC_FILE];
        struct inode *inode;
        struct f2fs_inode_info *fi;
next:
        spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
        if (list_empty(head)) {
                spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
                return;
        }
        fi = list_first_entry(head, struct f2fs_inode_info, inmem_ilist);
        inode = igrab(&fi->vfs_inode);
        spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);

        if (inode) {
                if (gc_failure) {
                        if (fi->i_gc_failures[GC_FAILURE_ATOMIC])
                                goto drop;
                        goto skip;
                }
drop:
                set_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST);
                f2fs_drop_inmem_pages(inode);
                iput(inode);
        }
skip:
        congestion_wait(BLK_RW_ASYNC, HZ/50);
        cond_resched();
        goto next;
}

void f2fs_drop_inmem_pages(struct inode *inode)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct f2fs_inode_info *fi = F2FS_I(inode);

        mutex_lock(&fi->inmem_lock);
        __revoke_inmem_pages(inode, &fi->inmem_pages, true, false);
        spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
        if (!list_empty(&fi->inmem_ilist))
                list_del_init(&fi->inmem_ilist);
        spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
        mutex_unlock(&fi->inmem_lock);

        clear_inode_flag(inode, FI_ATOMIC_FILE);
        fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0;
        stat_dec_atomic_write(inode);
}

void f2fs_drop_inmem_page(struct inode *inode, struct page *page)
{
        struct f2fs_inode_info *fi = F2FS_I(inode);
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct list_head *head = &fi->inmem_pages;
        struct inmem_pages *cur = NULL;

        f2fs_bug_on(sbi, !IS_ATOMIC_WRITTEN_PAGE(page));

        mutex_lock(&fi->inmem_lock);
        list_for_each_entry(cur, head, list) {
                if (cur->page == page)
                        break;
        }

        f2fs_bug_on(sbi, list_empty(head) || cur->page != page);
        list_del(&cur->list);
        mutex_unlock(&fi->inmem_lock);

        dec_page_count(sbi, F2FS_INMEM_PAGES);
        kmem_cache_free(inmem_entry_slab, cur);

        ClearPageUptodate(page);
        set_page_private(page, 0);
        ClearPagePrivate(page);
        f2fs_put_page(page, 0);

        trace_f2fs_commit_inmem_page(page, INMEM_INVALIDATE);
}

static int __f2fs_commit_inmem_pages(struct inode *inode)
{
        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,
                .ino = inode->i_ino,
                .type = DATA,
                .op = REQ_OP_WRITE,
                .op_flags = REQ_SYNC | REQ_PRIO,
                .io_type = FS_DATA_IO,
        };
        struct list_head revoke_list;
        pgoff_t last_idx = ULONG_MAX;
        int err = 0;

        INIT_LIST_HEAD(&revoke_list);

        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);
                                f2fs_remove_dirty_inode(inode);
                        }
retry:
                        fio.page = page;
                        fio.old_blkaddr = NULL_ADDR;
                        fio.encrypted_page = NULL;
                        fio.need_lock = LOCK_DONE;
                        err = f2fs_do_write_data_page(&fio);
                        if (err) {
                                if (err == -ENOMEM) {
                                        congestion_wait(BLK_RW_ASYNC, HZ/50);
                                        cond_resched();
                                        goto retry;
                                }
                                unlock_page(page);
                                break;
                        }
                        /* record old blkaddr for revoking */
                        cur->old_addr = fio.old_blkaddr;
                        last_idx = page->index;
                }
                unlock_page(page);
                list_move_tail(&cur->list, &revoke_list);
        }

        if (last_idx != ULONG_MAX)
                f2fs_submit_merged_write_cond(sbi, inode, 0, last_idx, DATA);

        if (err) {
                /*
                 * 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.
                 */
                err = __revoke_inmem_pages(inode, &revoke_list, false, true);

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

        return err;
}

int f2fs_commit_inmem_pages(struct inode *inode)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct f2fs_inode_info *fi = F2FS_I(inode);
        int err;

        f2fs_balance_fs(sbi, true);

        down_write(&fi->i_gc_rwsem[WRITE]);

        f2fs_lock_op(sbi);
        set_inode_flag(inode, FI_ATOMIC_COMMIT);

        mutex_lock(&fi->inmem_lock);
        err = __f2fs_commit_inmem_pages(inode);

        spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
        if (!list_empty(&fi->inmem_ilist))
                list_del_init(&fi->inmem_ilist);
        spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
        mutex_unlock(&fi->inmem_lock);

        clear_inode_flag(inode, FI_ATOMIC_COMMIT);

        f2fs_unlock_op(sbi);
        up_write(&fi->i_gc_rwsem[WRITE]);

        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)
{
        if (time_to_inject(sbi, FAULT_CHECKPOINT)) {
                f2fs_show_injection_info(FAULT_CHECKPOINT);
                f2fs_stop_checkpoint(sbi, false);
        }

        /* balance_fs_bg is able to be pending */
        if (need && 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, NULL_SEGNO);
        }
}

void f2fs_balance_fs_bg(struct f2fs_sb_info *sbi)
{
        if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
                return;

        /* try to shrink extent cache when there is no enough memory */
        if (!f2fs_available_free_memory(sbi, EXTENT_CACHE))
                f2fs_shrink_extent_tree(sbi, EXTENT_CACHE_SHRINK_NUMBER);

        /* check the # of cached NAT entries */
        if (!f2fs_available_free_memory(sbi, NAT_ENTRIES))
                f2fs_try_to_free_nats(sbi, NAT_ENTRY_PER_BLOCK);

        if (!f2fs_available_free_memory(sbi, FREE_NIDS))
                f2fs_try_to_free_nids(sbi, MAX_FREE_NIDS);
        else
                f2fs_build_free_nids(sbi, false, false);

        if (!is_idle(sbi) &&
                (!excess_dirty_nats(sbi) && !excess_dirty_nodes(sbi)))
                return;

        /* checkpoint is the only way to shrink partial cached entries */
        if (!f2fs_available_free_memory(sbi, NAT_ENTRIES) ||
                        !f2fs_available_free_memory(sbi, INO_ENTRIES) ||
                        excess_prefree_segs(sbi) ||
                        excess_dirty_nats(sbi) ||
                        excess_dirty_nodes(sbi) ||
                        f2fs_time_over(sbi, CP_TIME)) {
                if (test_opt(sbi, DATA_FLUSH)) {
                        struct blk_plug plug;

                        blk_start_plug(&plug);
                        f2fs_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 f2fs_sb_info *sbi,
                                struct block_device *bdev)
{
        struct bio *bio = f2fs_bio_alloc(sbi, 0, true);
        int ret;

        bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH;
        bio_set_dev(bio, bdev);
        ret = submit_bio_wait(bio);
        bio_put(bio);

        trace_f2fs_issue_flush(bdev, test_opt(sbi, NOBARRIER),
                                test_opt(sbi, FLUSH_MERGE), ret);
        return ret;
}

static int submit_flush_wait(struct f2fs_sb_info *sbi, nid_t ino)
{
        int ret = 0;
        int i;

        if (!sbi->s_ndevs)
                return __submit_flush_wait(sbi, sbi->sb->s_bdev);

        for (i = 0; i < sbi->s_ndevs; i++) {
                if (!f2fs_is_dirty_device(sbi, ino, i, FLUSH_INO))
                        continue;
                ret = __submit_flush_wait(sbi, 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)->fcc_info;
        wait_queue_head_t *q = &fcc->flush_wait_queue;
repeat:
        if (kthread_should_stop())
                return 0;

        sb_start_intwrite(sbi->sb);

        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);

                cmd = llist_entry(fcc->dispatch_list, struct flush_cmd, llnode);

                ret = submit_flush_wait(sbi, cmd->ino);
                atomic_inc(&fcc->issued_flush);

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

        sb_end_intwrite(sbi->sb);

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

int f2fs_issue_flush(struct f2fs_sb_info *sbi, nid_t ino)
{
        struct flush_cmd_control *fcc = SM_I(sbi)->fcc_info;
        struct flush_cmd cmd;
        int ret;

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

        if (!test_opt(sbi, FLUSH_MERGE)) {
                ret = submit_flush_wait(sbi, ino);
                atomic_inc(&fcc->issued_flush);
                return ret;
        }

        if (atomic_inc_return(&fcc->issing_flush) == 1 || sbi->s_ndevs > 1) {
                ret = submit_flush_wait(sbi, ino);
                atomic_dec(&fcc->issing_flush);

                atomic_inc(&fcc->issued_flush);
                return ret;
        }

        cmd.ino = ino;
        init_completion(&cmd.wait);

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

        /* update issue_list before we wake up issue_flush thread */
        smp_mb();

        if (waitqueue_active(&fcc->flush_wait_queue))
                wake_up(&fcc->flush_wait_queue);

        if (fcc->f2fs_issue_flush) {
                wait_for_completion(&cmd.wait);
                atomic_dec(&fcc->issing_flush);
        } else {
                struct llist_node *list;

                list = llist_del_all(&fcc->issue_list);
                if (!list) {
                        wait_for_completion(&cmd.wait);
                        atomic_dec(&fcc->issing_flush);
                } else {
                        struct flush_cmd *tmp, *next;

                        ret = submit_flush_wait(sbi, ino);

                        llist_for_each_entry_safe(tmp, next, list, llnode) {
                                if (tmp == &cmd) {
                                        cmd.ret = ret;
                                        atomic_dec(&fcc->issing_flush);
                                        continue;
                                }
                                tmp->ret = ret;
                                complete(&tmp->wait);
                        }
                }
        }

        return cmd.ret;
}

int f2fs_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)->fcc_info) {
                fcc = SM_I(sbi)->fcc_info;
                if (fcc->f2fs_issue_flush)
                        return err;
                goto init_thread;
        }

        fcc = f2fs_kzalloc(sbi, sizeof(struct flush_cmd_control), GFP_KERNEL);
        if (!fcc)
                return -ENOMEM;
        atomic_set(&fcc->issued_flush, 0);
        atomic_set(&fcc->issing_flush, 0);
        init_waitqueue_head(&fcc->flush_wait_queue);
        init_llist_head(&fcc->issue_list);
        SM_I(sbi)->fcc_info = fcc;
        if (!test_opt(sbi, FLUSH_MERGE))
                return err;

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)->fcc_info = NULL;
                return err;
        }

        return err;
}

void f2fs_destroy_flush_cmd_control(struct f2fs_sb_info *sbi, bool free)
{
        struct flush_cmd_control *fcc = SM_I(sbi)->fcc_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)->fcc_info = NULL;
        }
}

int f2fs_flush_device_cache(struct f2fs_sb_info *sbi)
{
        int ret = 0, i;

        if (!sbi->s_ndevs)
                return 0;

        for (i = 1; i < sbi->s_ndevs; i++) {
                if (!f2fs_test_bit(i, (char *)&sbi->dirty_device))
                        continue;
                ret = __submit_flush_wait(sbi, FDEV(i).bdev);
                if (ret)
                        break;

                spin_lock(&sbi->dev_lock);
                f2fs_clear_bit(i, (char *)&sbi->dirty_device);
                spin_unlock(&sbi->dev_lock);
        }

        return ret;
}

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, true) == 0)
                        clear_bit(GET_SEC_FROM_SEG(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, false);

        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 discard_cmd *__create_discard_cmd(struct f2fs_sb_info *sbi,
                struct block_device *bdev, block_t lstart,
                block_t start, block_t len)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        struct list_head *pend_list;
        struct discard_cmd *dc;

        f2fs_bug_on(sbi, !len);

        pend_list = &dcc->pend_list[plist_idx(len)];

        dc = f2fs_kmem_cache_alloc(discard_cmd_slab, GFP_NOFS);
        INIT_LIST_HEAD(&dc->list);
        dc->bdev = bdev;
        dc->lstart = lstart;
        dc->start = start;
        dc->len = len;
        dc->ref = 0;
        dc->state = D_PREP;
        dc->issuing = 0;
        dc->error = 0;
        init_completion(&dc->wait);
        list_add_tail(&dc->list, pend_list);
        spin_lock_init(&dc->lock);
        dc->bio_ref = 0;
        atomic_inc(&dcc->discard_cmd_cnt);
        dcc->undiscard_blks += len;

        return dc;
}

static struct discard_cmd *__attach_discard_cmd(struct f2fs_sb_info *sbi,
                                struct block_device *bdev, block_t lstart,
                                block_t start, block_t len,
                                struct rb_node *parent, struct rb_node **p)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        struct discard_cmd *dc;

        dc = __create_discard_cmd(sbi, bdev, lstart, start, len);

        rb_link_node(&dc->rb_node, parent, p);
        rb_insert_color(&dc->rb_node, &dcc->root);

        return dc;
}

static void __detach_discard_cmd(struct discard_cmd_control *dcc,
                                                        struct discard_cmd *dc)
{
        if (dc->state == D_DONE)
                atomic_sub(dc->issuing, &dcc->issing_discard);

        list_del(&dc->list);
        rb_erase(&dc->rb_node, &dcc->root);
        dcc->undiscard_blks -= dc->len;

        kmem_cache_free(discard_cmd_slab, dc);

        atomic_dec(&dcc->discard_cmd_cnt);
}

static void __remove_discard_cmd(struct f2fs_sb_info *sbi,
                                                        struct discard_cmd *dc)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        unsigned long flags;

        trace_f2fs_remove_discard(dc->bdev, dc->start, dc->len);

        spin_lock_irqsave(&dc->lock, flags);
        if (dc->bio_ref) {
                spin_unlock_irqrestore(&dc->lock, flags);
                return;
        }
        spin_unlock_irqrestore(&dc->lock, flags);

        f2fs_bug_on(sbi, dc->ref);

        if (dc->error == -EOPNOTSUPP)
                dc->error = 0;

        if (dc->error)
                f2fs_msg(sbi->sb, KERN_INFO,
                        "Issue discard(%u, %u, %u) failed, ret: %d",
                        dc->lstart, dc->start, dc->len, dc->error);
        __detach_discard_cmd(dcc, dc);
}

static void f2fs_submit_discard_endio(struct bio *bio)
{
        struct discard_cmd *dc = (struct discard_cmd *)bio->bi_private;
        unsigned long flags;

        dc->error = blk_status_to_errno(bio->bi_status);

        spin_lock_irqsave(&dc->lock, flags);
        dc->bio_ref--;
        if (!dc->bio_ref && dc->state == D_SUBMIT) {
                dc->state = D_DONE;
                complete_all(&dc->wait);
        }
        spin_unlock_irqrestore(&dc->lock, flags);
        bio_put(bio);
}

static void __check_sit_bitmap(struct f2fs_sb_info *sbi,
                                block_t start, block_t end)
{
#ifdef CONFIG_F2FS_CHECK_FS
        struct seg_entry *sentry;
        unsigned int segno;
        block_t blk = start;
        unsigned long offset, size, max_blocks = sbi->blocks_per_seg;
        unsigned long *map;

        while (blk < end) {
                segno = GET_SEGNO(sbi, blk);
                sentry = get_seg_entry(sbi, segno);
                offset = GET_BLKOFF_FROM_SEG0(sbi, blk);

                if (end < START_BLOCK(sbi, segno + 1))
                        size = GET_BLKOFF_FROM_SEG0(sbi, end);
                else
                        size = max_blocks;
                map = (unsigned long *)(sentry->cur_valid_map);
                offset = __find_rev_next_bit(map, size, offset);
                f2fs_bug_on(sbi, offset != size);
                blk = START_BLOCK(sbi, segno + 1);
        }
#endif
}

static void __init_discard_policy(struct f2fs_sb_info *sbi,
                                struct discard_policy *dpolicy,
                                int discard_type, unsigned int granularity)
{
        /* common policy */
        dpolicy->type = discard_type;
        dpolicy->sync = true;
        dpolicy->ordered = false;
        dpolicy->granularity = granularity;

        dpolicy->max_requests = DEF_MAX_DISCARD_REQUEST;
        dpolicy->io_aware_gran = MAX_PLIST_NUM;

        if (discard_type == DPOLICY_BG) {
                dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
                dpolicy->mid_interval = DEF_MID_DISCARD_ISSUE_TIME;
                dpolicy->max_interval = DEF_MAX_DISCARD_ISSUE_TIME;
                dpolicy->io_aware = true;
                dpolicy->sync = false;
                dpolicy->ordered = true;
                if (utilization(sbi) > DEF_DISCARD_URGENT_UTIL) {
                        dpolicy->granularity = 1;
                        dpolicy->max_interval = DEF_MIN_DISCARD_ISSUE_TIME;
                }
        } else if (discard_type == DPOLICY_FORCE) {
                dpolicy->min_interval = DEF_MIN_DISCARD_ISSUE_TIME;
                dpolicy->mid_interval = DEF_MID_DISCARD_ISSUE_TIME;
                dpolicy->max_interval = DEF_MAX_DISCARD_ISSUE_TIME;
                dpolicy->io_aware = false;
        } else if (discard_type == DPOLICY_FSTRIM) {
                dpolicy->io_aware = false;
        } else if (discard_type == DPOLICY_UMOUNT) {
                dpolicy->max_requests = UINT_MAX;
                dpolicy->io_aware = false;
        }
}

static void __update_discard_tree_range(struct f2fs_sb_info *sbi,
                                struct block_device *bdev, block_t lstart,
                                block_t start, block_t len);
/* this function is copied from blkdev_issue_discard from block/blk-lib.c */
static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
                                                struct discard_policy *dpolicy,

                                                struct discard_cmd *dc,
                                                unsigned int *issued)
{
        struct block_device *bdev = dc->bdev;
        struct request_queue *q = bdev_get_queue(bdev);
        unsigned int max_discard_blocks =
                        SECTOR_TO_BLOCK(q->limits.max_discard_sectors);
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        struct list_head *wait_list = (dpolicy->type == DPOLICY_FSTRIM) ?
                                        &(dcc->fstrim_list) : &(dcc->wait_list);
        int flag = dpolicy->sync ? REQ_SYNC : 0;
        block_t lstart, start, len, total_len;
        int err = 0;

        if (dc->state != D_PREP)
                return 0;

        if (is_sbi_flag_set(sbi, SBI_NEED_FSCK))
                return 0;

        trace_f2fs_issue_discard(bdev, dc->start, dc->len);

        lstart = dc->lstart;
        start = dc->start;
        len = dc->len;
        total_len = len;

        dc->len = 0;

        while (total_len && *issued < dpolicy->max_requests && !err) {
                struct bio *bio = NULL;
                unsigned long flags;
                bool last = true;

                if (len > max_discard_blocks) {
                        len = max_discard_blocks;
                        last = false;
                }

                (*issued)++;
                if (*issued == dpolicy->max_requests)
                        last = true;

                dc->len += len;

                if (time_to_inject(sbi, FAULT_DISCARD)) {
                        f2fs_show_injection_info(FAULT_DISCARD);
                        err = -EIO;
                        goto submit;
                }
                err = __blkdev_issue_discard(bdev,
                                        SECTOR_FROM_BLOCK(start),
                                        SECTOR_FROM_BLOCK(len),
                                        GFP_NOFS, 0, &bio);
submit:
                if (err) {
                        spin_lock_irqsave(&dc->lock, flags);
                        if (dc->state == D_PARTIAL)
                                dc->state = D_SUBMIT;
                        spin_unlock_irqrestore(&dc->lock, flags);

                        break;
                }

                f2fs_bug_on(sbi, !bio);

                /*
                 * should keep before submission to avoid D_DONE
                 * right away
                 */
                spin_lock_irqsave(&dc->lock, flags);
                if (last)
                        dc->state = D_SUBMIT;
                else
                        dc->state = D_PARTIAL;
                dc->bio_ref++;
                spin_unlock_irqrestore(&dc->lock, flags);

                atomic_inc(&dcc->issing_discard);
                dc->issuing++;
                list_move_tail(&dc->list, wait_list);

                /* sanity check on discard range */
                __check_sit_bitmap(sbi, start, start + len);

                bio->bi_private = dc;
                bio->bi_end_io = f2fs_submit_discard_endio;
                bio->bi_opf |= flag;
                submit_bio(bio);

                atomic_inc(&dcc->issued_discard);

                f2fs_update_iostat(sbi, FS_DISCARD, 1);

                lstart += len;
                start += len;
                total_len -= len;
                len = total_len;
        }

        if (!err && len)
                __update_discard_tree_range(sbi, bdev, lstart, start, len);
        return err;
}

static struct discard_cmd *__insert_discard_tree(struct f2fs_sb_info *sbi,
                                struct block_device *bdev, block_t lstart,
                                block_t start, block_t len,
                                struct rb_node **insert_p,
                                struct rb_node *insert_parent)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        struct rb_node **p;
        struct rb_node *parent = NULL;
        struct discard_cmd *dc = NULL;

        if (insert_p && insert_parent) {
                parent = insert_parent;
                p = insert_p;
                goto do_insert;
        }

        p = f2fs_lookup_rb_tree_for_insert(sbi, &dcc->root, &parent, lstart);
do_insert:
        dc = __attach_discard_cmd(sbi, bdev, lstart, start, len, parent, p);
        if (!dc)
                return NULL;

        return dc;
}

static void __relocate_discard_cmd(struct discard_cmd_control *dcc,
                                                struct discard_cmd *dc)
{
        list_move_tail(&dc->list, &dcc->pend_list[plist_idx(dc->len)]);
}

static void __punch_discard_cmd(struct f2fs_sb_info *sbi,
                                struct discard_cmd *dc, block_t blkaddr)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        struct discard_info di = dc->di;
        bool modified = false;

        if (dc->state == D_DONE || dc->len == 1) {
                __remove_discard_cmd(sbi, dc);
                return;
        }

        dcc->undiscard_blks -= di.len;

        if (blkaddr > di.lstart) {
                dc->len = blkaddr - dc->lstart;
                dcc->undiscard_blks += dc->len;
                __relocate_discard_cmd(dcc, dc);
                modified = true;
        }

        if (blkaddr < di.lstart + di.len - 1) {
                if (modified) {
                        __insert_discard_tree(sbi, dc->bdev, blkaddr + 1,
                                        di.start + blkaddr + 1 - di.lstart,
                                        di.lstart + di.len - 1 - blkaddr,
                                        NULL, NULL);
                } else {
                        dc->lstart++;
                        dc->len--;
                        dc->start++;
                        dcc->undiscard_blks += dc->len;
                        __relocate_discard_cmd(dcc, dc);
                }
        }
}

static void __update_discard_tree_range(struct f2fs_sb_info *sbi,
                                struct block_device *bdev, block_t lstart,
                                block_t start, block_t len)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        struct discard_cmd *prev_dc = NULL, *next_dc = NULL;
        struct discard_cmd *dc;
        struct discard_info di = {0};
        struct rb_node **insert_p = NULL, *insert_parent = NULL;
        struct request_queue *q = bdev_get_queue(bdev);
        unsigned int max_discard_blocks =
                        SECTOR_TO_BLOCK(q->limits.max_discard_sectors);
        block_t end = lstart + len;

        dc = (struct discard_cmd *)f2fs_lookup_rb_tree_ret(&dcc->root,
                                        NULL, lstart,
                                        (struct rb_entry **)&prev_dc,
                                        (struct rb_entry **)&next_dc,
                                        &insert_p, &insert_parent, true);
        if (dc)
                prev_dc = dc;

        if (!prev_dc) {
                di.lstart = lstart;
                di.len = next_dc ? next_dc->lstart - lstart : len;
                di.len = min(di.len, len);
                di.start = start;
        }

        while (1) {
                struct rb_node *node;
                bool merged = false;
                struct discard_cmd *tdc = NULL;

                if (prev_dc) {
                        di.lstart = prev_dc->lstart + prev_dc->len;
                        if (di.lstart < lstart)
                                di.lstart = lstart;
                        if (di.lstart >= end)
                                break;

                        if (!next_dc || next_dc->lstart > end)
                                di.len = end - di.lstart;
                        else
                                di.len = next_dc->lstart - di.lstart;
                        di.start = start + di.lstart - lstart;
                }

                if (!di.len)
                        goto next;

                if (prev_dc && prev_dc->state == D_PREP &&
                        prev_dc->bdev == bdev &&
                        __is_discard_back_mergeable(&di, &prev_dc->di,
                                                        max_discard_blocks)) {
                        prev_dc->di.len += di.len;
                        dcc->undiscard_blks += di.len;
                        __relocate_discard_cmd(dcc, prev_dc);
                        di = prev_dc->di;
                        tdc = prev_dc;
                        merged = true;
                }

                if (next_dc && next_dc->state == D_PREP &&
                        next_dc->bdev == bdev &&
                        __is_discard_front_mergeable(&di, &next_dc->di,
                                                        max_discard_blocks)) {
                        next_dc->di.lstart = di.lstart;
                        next_dc->di.len += di.len;
                        next_dc->di.start = di.start;
                        dcc->undiscard_blks += di.len;
                        __relocate_discard_cmd(dcc, next_dc);
                        if (tdc)
                                __remove_discard_cmd(sbi, tdc);
                        merged = true;
                }

                if (!merged) {
                        __insert_discard_tree(sbi, bdev, di.lstart, di.start,
                                                        di.len, NULL, NULL);
                }
 next:
                prev_dc = next_dc;
                if (!prev_dc)
                        break;

                node = rb_next(&prev_dc->rb_node);
                next_dc = rb_entry_safe(node, struct discard_cmd, rb_node);
        }
}

static int __queue_discard_cmd(struct f2fs_sb_info *sbi,
                struct block_device *bdev, block_t blkstart, block_t blklen)
{
        block_t lblkstart = blkstart;

        trace_f2fs_queue_discard(bdev, blkstart, blklen);

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

                blkstart -= FDEV(devi).start_blk;
        }
        mutex_lock(&SM_I(sbi)->dcc_info->cmd_lock);
        __update_discard_tree_range(sbi, bdev, lblkstart, blkstart, blklen);
        mutex_unlock(&SM_I(sbi)->dcc_info->cmd_lock);
        return 0;
}

static unsigned int __issue_discard_cmd_orderly(struct f2fs_sb_info *sbi,
                                        struct discard_policy *dpolicy)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        struct discard_cmd *prev_dc = NULL, *next_dc = NULL;
        struct rb_node **insert_p = NULL, *insert_parent = NULL;
        struct discard_cmd *dc;
        struct blk_plug plug;
        unsigned int pos = dcc->next_pos;
        unsigned int issued = 0;
        bool io_interrupted = false;

        mutex_lock(&dcc->cmd_lock);
        dc = (struct discard_cmd *)f2fs_lookup_rb_tree_ret(&dcc->root,
                                        NULL, pos,
                                        (struct rb_entry **)&prev_dc,
                                        (struct rb_entry **)&next_dc,
                                        &insert_p, &insert_parent, true);
        if (!dc)
                dc = next_dc;

        blk_start_plug(&plug);

        while (dc) {
                struct rb_node *node;
                int err = 0;

                if (dc->state != D_PREP)
                        goto next;

                if (dpolicy->io_aware && !is_idle(sbi)) {
                        io_interrupted = true;
                        break;
                }

                dcc->next_pos = dc->lstart + dc->len;
                err = __submit_discard_cmd(sbi, dpolicy, dc, &issued);

                if (issued >= dpolicy->max_requests)
                        break;
next:
                node = rb_next(&dc->rb_node);
                if (err)
                        __remove_discard_cmd(sbi, dc);
                dc = rb_entry_safe(node, struct discard_cmd, rb_node);
        }

        blk_finish_plug(&plug);

        if (!dc)
                dcc->next_pos = 0;

        mutex_unlock(&dcc->cmd_lock);

        if (!issued && io_interrupted)
                issued = -1;

        return issued;
}

static int __issue_discard_cmd(struct f2fs_sb_info *sbi,
                                        struct discard_policy *dpolicy)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        struct list_head *pend_list;
        struct discard_cmd *dc, *tmp;
        struct blk_plug plug;
        int i, issued = 0;
        bool io_interrupted = false;

        for (i = MAX_PLIST_NUM - 1; i >= 0; i--) {
                if (i + 1 < dpolicy->granularity)
                        break;

                if (i < DEFAULT_DISCARD_GRANULARITY && dpolicy->ordered)
                        return __issue_discard_cmd_orderly(sbi, dpolicy);

                pend_list = &dcc->pend_list[i];

                mutex_lock(&dcc->cmd_lock);
                if (list_empty(pend_list))
                        goto next;
                if (unlikely(dcc->rbtree_check))
                        f2fs_bug_on(sbi, !f2fs_check_rb_tree_consistence(sbi,
                                                                &dcc->root));
                blk_start_plug(&plug);
                list_for_each_entry_safe(dc, tmp, pend_list, list) {
                        f2fs_bug_on(sbi, dc->state != D_PREP);

                        if (dpolicy->io_aware && i < dpolicy->io_aware_gran &&
                                                                !is_idle(sbi)) {
                                io_interrupted = true;
                                break;
                        }

                        __submit_discard_cmd(sbi, dpolicy, dc, &issued);

                        if (issued >= dpolicy->max_requests)
                                break;
                }
                blk_finish_plug(&plug);
next:
                mutex_unlock(&dcc->cmd_lock);

                if (issued >= dpolicy->max_requests || io_interrupted)
                        break;
        }

        if (!issued && io_interrupted)
                issued = -1;

        return issued;
}

static bool __drop_discard_cmd(struct f2fs_sb_info *sbi)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        struct list_head *pend_list;
        struct discard_cmd *dc, *tmp;
        int i;
        bool dropped = false;

        mutex_lock(&dcc->cmd_lock);
        for (i = MAX_PLIST_NUM - 1; i >= 0; i--) {
                pend_list = &dcc->pend_list[i];
                list_for_each_entry_safe(dc, tmp, pend_list, list) {
                        f2fs_bug_on(sbi, dc->state != D_PREP);
                        __remove_discard_cmd(sbi, dc);
                        dropped = true;
                }
        }
        mutex_unlock(&dcc->cmd_lock);

        return dropped;
}

void f2fs_drop_discard_cmd(struct f2fs_sb_info *sbi)
{
        __drop_discard_cmd(sbi);
}

static unsigned int __wait_one_discard_bio(struct f2fs_sb_info *sbi,
                                                        struct discard_cmd *dc)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        unsigned int len = 0;

        wait_for_completion_io(&dc->wait);
        mutex_lock(&dcc->cmd_lock);
        f2fs_bug_on(sbi, dc->state != D_DONE);
        dc->ref--;
        if (!dc->ref) {
                if (!dc->error)
                        len = dc->len;
                __remove_discard_cmd(sbi, dc);
        }
        mutex_unlock(&dcc->cmd_lock);

        return len;
}

static unsigned int __wait_discard_cmd_range(struct f2fs_sb_info *sbi,
                                                struct discard_policy *dpolicy,
                                                block_t start, block_t end)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        struct list_head *wait_list = (dpolicy->type == DPOLICY_FSTRIM) ?
                                        &(dcc->fstrim_list) : &(dcc->wait_list);
        struct discard_cmd *dc, *tmp;
        bool need_wait;
        unsigned int trimmed = 0;

next:
        need_wait = false;

        mutex_lock(&dcc->cmd_lock);
        list_for_each_entry_safe(dc, tmp, wait_list, list) {
                if (dc->lstart + dc->len <= start || end <= dc->lstart)
                        continue;
                if (dc->len < dpolicy->granularity)
                        continue;
                if (dc->state == D_DONE && !dc->ref) {
                        wait_for_completion_io(&dc->wait);
                        if (!dc->error)
                                trimmed += dc->len;
                        __remove_discard_cmd(sbi, dc);
                } else {
                        dc->ref++;
                        need_wait = true;
                        break;
                }
        }
        mutex_unlock(&dcc->cmd_lock);

        if (need_wait) {
                trimmed += __wait_one_discard_bio(sbi, dc);
                goto next;
        }

        return trimmed;
}

static unsigned int __wait_all_discard_cmd(struct f2fs_sb_info *sbi,
                                                struct discard_policy *dpolicy)
{
        struct discard_policy dp;
        unsigned int discard_blks;

        if (dpolicy)
                return __wait_discard_cmd_range(sbi, dpolicy, 0, UINT_MAX);

        /* wait all */
        __init_discard_policy(sbi, &dp, DPOLICY_FSTRIM, 1);
        discard_blks = __wait_discard_cmd_range(sbi, &dp, 0, UINT_MAX);
        __init_discard_policy(sbi, &dp, DPOLICY_UMOUNT, 1);
        discard_blks += __wait_discard_cmd_range(sbi, &dp, 0, UINT_MAX);

        return discard_blks;
}

/* This should be covered by global mutex, &sit_i->sentry_lock */
static void f2fs_wait_discard_bio(struct f2fs_sb_info *sbi, block_t blkaddr)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        struct discard_cmd *dc;
        bool need_wait = false;

        mutex_lock(&dcc->cmd_lock);
        dc = (struct discard_cmd *)f2fs_lookup_rb_tree(&dcc->root,
                                                        NULL, blkaddr);
        if (dc) {
                if (dc->state == D_PREP) {
                        __punch_discard_cmd(sbi, dc, blkaddr);
                } else {
                        dc->ref++;
                        need_wait = true;
                }
        }
        mutex_unlock(&dcc->cmd_lock);

        if (need_wait)
                __wait_one_discard_bio(sbi, dc);
}

void f2fs_stop_discard_thread(struct f2fs_sb_info *sbi)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;

        if (dcc && dcc->f2fs_issue_discard) {
                struct task_struct *discard_thread = dcc->f2fs_issue_discard;

                dcc->f2fs_issue_discard = NULL;
                kthread_stop(discard_thread);
        }
}

/* This comes from f2fs_put_super */
bool f2fs_wait_discard_bios(struct f2fs_sb_info *sbi)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        struct discard_policy dpolicy;
        bool dropped;

        __init_discard_policy(sbi, &dpolicy, DPOLICY_UMOUNT,
                                        dcc->discard_granularity);
        __issue_discard_cmd(sbi, &dpolicy);
        dropped = __drop_discard_cmd(sbi);

        /* just to make sure there is no pending discard commands */
        __wait_all_discard_cmd(sbi, NULL);

        f2fs_bug_on(sbi, atomic_read(&dcc->discard_cmd_cnt));
        return dropped;
}

static int issue_discard_thread(void *data)
{
        struct f2fs_sb_info *sbi = data;
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        wait_queue_head_t *q = &dcc->discard_wait_queue;
        struct discard_policy dpolicy;
        unsigned int wait_ms = DEF_MIN_DISCARD_ISSUE_TIME;
        int issued;

        set_freezable();

        do {
                __init_discard_policy(sbi, &dpolicy, DPOLICY_BG,
                                        dcc->discard_granularity);

                wait_event_interruptible_timeout(*q,
                                kthread_should_stop() || freezing(current) ||
                                dcc->discard_wake,
                                msecs_to_jiffies(wait_ms));

                if (dcc->discard_wake)
                        dcc->discard_wake = 0;

                if (try_to_freeze())
                        continue;
                if (f2fs_readonly(sbi->sb))
                        continue;
                if (kthread_should_stop())
                        return 0;
                if (is_sbi_flag_set(sbi, SBI_NEED_FSCK)) {
                        wait_ms = dpolicy.max_interval;
                        continue;
                }

                if (sbi->gc_mode == GC_URGENT)
                        __init_discard_policy(sbi, &dpolicy, DPOLICY_FORCE, 1);

                sb_start_intwrite(sbi->sb);

                issued = __issue_discard_cmd(sbi, &dpolicy);
                if (issued > 0) {
                        __wait_all_discard_cmd(sbi, &dpolicy);
                        wait_ms = dpolicy.min_interval;
                } else if (issued == -1){
                        wait_ms = dpolicy.mid_interval;
                } else {
                        wait_ms = dpolicy.max_interval;
                }

                sb_end_intwrite(sbi->sb);

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

#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 sector, nr_sects;
        block_t lblkstart = blkstart;
        int devi = 0;

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

        /*
         * 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 __queue_discard_cmd(sbi, bdev, lblkstart, blklen);
        case BLK_ZONE_TYPE_SEQWRITE_REQ:
        case BLK_ZONE_TYPE_SEQWRITE_PREF:
                sector = SECTOR_FROM_BLOCK(blkstart);
                nr_sects = SECTOR_FROM_BLOCK(blklen);

                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;
                }
                trace_f2fs_issue_reset_zone(bdev, 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_has_blkzoned(sbi->sb) &&
                                bdev_zoned_model(bdev) != BLK_ZONED_NONE)
                return __f2fs_issue_discard_zone(sbi, bdev, blkstart, blklen);
#endif
        return __queue_discard_cmd(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 bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc,
                                                        bool check_only)
{
        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);
        struct discard_entry *de = NULL;
        struct list_head *head = &SM_I(sbi)->dcc_info->entry_list;
        int i;

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

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

        /* 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)->dcc_info->nr_discards <=
                                SM_I(sbi)->dcc_info->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;

                if (check_only)
                        return true;

                if (!de) {
                        de = f2fs_kmem_cache_alloc(discard_entry_slab,
                                                                GFP_F2FS_ZERO);
                        de->start_blkaddr = START_BLOCK(sbi, cpc->trim_start);
                        list_add_tail(&de->list, head);
                }

                for (i = start; i < end; i++)
                        __set_bit_le(i, (void *)de->discard_map);

                SM_I(sbi)->dcc_info->nr_discards += end - start;
        }
        return false;
}

static void release_discard_addr(struct discard_entry *entry)
{
        list_del(&entry->list);
        kmem_cache_free(discard_entry_slab, entry);
}

void f2fs_release_discard_addrs(struct f2fs_sb_info *sbi)
{
        struct list_head *head = &(SM_I(sbi)->dcc_info->entry_list);
        struct discard_entry *entry, *this;

        /* drop caches */
        list_for_each_entry_safe(entry, this, head, list)
                release_discard_addr(entry);
}

/*
 * Should call f2fs_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 f2fs_clear_prefree_segments(struct f2fs_sb_info *sbi,
                                                struct cp_control *cpc)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        struct list_head *head = &dcc->entry_list;
        struct discard_entry *entry, *this;
        struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
        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);
        bool need_align = test_opt(sbi, LFS) && sbi->segs_per_sec > 1;

        mutex_lock(&dirty_i->seglist_lock);

        while (1) {
                int i;

                if (need_align && end != -1)
                        end--;
                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);

                if (need_align) {
                        start = rounddown(start, sbi->segs_per_sec);
                        end = roundup(end, sbi->segs_per_sec);
                }

                for (i = start; i < end; i++) {
                        if (test_and_clear_bit(i, prefree_map))
                                dirty_i->nr_dirty[PRE]--;
                }

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

                if (force && start >= cpc->trim_start &&
                                        (end - 1) <= cpc->trim_end)
                                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_SEC_FROM_SEG(sbi, start);
                start_segno = GET_SEG_FROM_SEC(sbi, secno);
                if (!IS_CURSEC(sbi, secno) &&
                        !get_valid_blocks(sbi, start, true))
                        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;
                else
                        end = start - 1;
        }
        mutex_unlock(&dirty_i->seglist_lock);

        /* send small discards */
        list_for_each_entry_safe(entry, this, head, list) {
                unsigned int cur_pos = 0, next_pos, len, total_len = 0;
                bool is_valid = test_bit_le(0, entry->discard_map);

find_next:
                if (is_valid) {
                        next_pos = find_next_zero_bit_le(entry->discard_map,
                                        sbi->blocks_per_seg, cur_pos);
                        len = next_pos - cur_pos;

                        if (f2fs_sb_has_blkzoned(sbi->sb) ||
                            (force && len < cpc->trim_minlen))
                                goto skip;

                        f2fs_issue_discard(sbi, entry->start_blkaddr + cur_pos,
                                                                        len);
                        total_len += len;
                } else {
                        next_pos = find_next_bit_le(entry->discard_map,
                                        sbi->blocks_per_seg, cur_pos);
                }
skip:
                cur_pos = next_pos;
                is_valid = !is_valid;

                if (cur_pos < sbi->blocks_per_seg)
                        goto find_next;

                release_discard_addr(entry);
                dcc->nr_discards -= total_len;
        }

        wake_up_discard_thread(sbi, false);
}

static int create_discard_cmd_control(struct f2fs_sb_info *sbi)
{
        dev_t dev = sbi->sb->s_bdev->bd_dev;
        struct discard_cmd_control *dcc;
        int err = 0, i;

        if (SM_I(sbi)->dcc_info) {
                dcc = SM_I(sbi)->dcc_info;
                goto init_thread;
        }

        dcc = f2fs_kzalloc(sbi, sizeof(struct discard_cmd_control), GFP_KERNEL);
        if (!dcc)
                return -ENOMEM;

        dcc->discard_granularity = DEFAULT_DISCARD_GRANULARITY;
        INIT_LIST_HEAD(&dcc->entry_list);
        for (i = 0; i < MAX_PLIST_NUM; i++)
                INIT_LIST_HEAD(&dcc->pend_list[i]);
        INIT_LIST_HEAD(&dcc->wait_list);
        INIT_LIST_HEAD(&dcc->fstrim_list);
        mutex_init(&dcc->cmd_lock);
        atomic_set(&dcc->issued_discard, 0);
        atomic_set(&dcc->issing_discard, 0);
        atomic_set(&dcc->discard_cmd_cnt, 0);
        dcc->nr_discards = 0;
        dcc->max_discards = MAIN_SEGS(sbi) << sbi->log_blocks_per_seg;
        dcc->undiscard_blks = 0;
        dcc->next_pos = 0;
        dcc->root = RB_ROOT;
        dcc->rbtree_check = false;

        init_waitqueue_head(&dcc->discard_wait_queue);
        SM_I(sbi)->dcc_info = dcc;
init_thread:
        dcc->f2fs_issue_discard = kthread_run(issue_discard_thread, sbi,
                                "f2fs_discard-%u:%u", MAJOR(dev), MINOR(dev));
        if (IS_ERR(dcc->f2fs_issue_discard)) {
                err = PTR_ERR(dcc->f2fs_issue_discard);
                kfree(dcc);
                SM_I(sbi)->dcc_info = NULL;
                return err;
        }

        return err;
}

static void destroy_discard_cmd_control(struct f2fs_sb_info *sbi)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;

        if (!dcc)
                return;

        f2fs_stop_discard_thread(sbi);

        kfree(dcc);
        SM_I(sbi)->dcc_info = NULL;
}

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;
        bool exist;
#ifdef CONFIG_F2FS_CHECK_FS
        bool mir_exist;
#endif

        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, false);
        if (se->mtime > SIT_I(sbi)->max_mtime)
                SIT_I(sbi)->max_mtime = se->mtime;

        /* Update valid block bitmap */
        if (del > 0) {
                exist = f2fs_test_and_set_bit(offset, se->cur_valid_map);
#ifdef CONFIG_F2FS_CHECK_FS
                mir_exist = f2fs_test_and_set_bit(offset,
                                                se->cur_valid_map_mir);
                if (unlikely(exist != mir_exist)) {
                        f2fs_msg(sbi->sb, KERN_ERR, "Inconsistent error "
                                "when setting bitmap, blk:%u, old bit:%d",
                                blkaddr, exist);
                        f2fs_bug_on(sbi, 1);
                }
#endif
                if (unlikely(exist)) {
                        f2fs_msg(sbi->sb, KERN_ERR,
                                "Bitmap was wrongly set, blk:%u", blkaddr);
                        f2fs_bug_on(sbi, 1);
                        se->valid_blocks--;
                        del = 0;
                }

                if (f2fs_discard_en(sbi) &&
                        !f2fs_test_and_set_bit(offset, se->discard_map))
                        sbi->discard_blks--;

                /* don't overwrite by SSR to keep node chain */
                if (IS_NODESEG(se->type)) {
                        if (!f2fs_test_and_set_bit(offset, se->ckpt_valid_map))
                                se->ckpt_valid_blocks++;
                }
        } else {
                exist = f2fs_test_and_clear_bit(offset, se->cur_valid_map);
#ifdef CONFIG_F2FS_CHECK_FS
                mir_exist = f2fs_test_and_clear_bit(offset,
                                                se->cur_valid_map_mir);
                if (unlikely(exist != mir_exist)) {
                        f2fs_msg(sbi->sb, KERN_ERR, "Inconsistent error "
                                "when clearing bitmap, blk:%u, old bit:%d",
                                blkaddr, exist);
                        f2fs_bug_on(sbi, 1);
                }
#endif
                if (unlikely(!exist)) {
                        f2fs_msg(sbi->sb, KERN_ERR,
                                "Bitmap was wrongly cleared, blk:%u", blkaddr);
                        f2fs_bug_on(sbi, 1);
                        se->valid_blocks++;
                        del = 0;
                }

                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 f2fs_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;

        invalidate_mapping_pages(META_MAPPING(sbi), addr, addr);

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

        update_sit_entry(sbi, addr, -1);

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

        up_write(&sit_i->sentry_lock);
}

bool f2fs_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 (!is_valid_data_blkaddr(sbi, blkaddr))
                return true;

        down_read(&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;

        up_read(&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 f2fs_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 *f2fs_get_sum_page(struct f2fs_sb_info *sbi, unsigned int segno)
{
        return f2fs_get_meta_page_nofail(sbi, GET_SUM_BLOCK(sbi, segno));
}

void f2fs_update_meta_page(struct f2fs_sb_info *sbi,
                                        void *src, block_t blk_addr)
{
        struct page *page = f2fs_grab_meta_page(sbi, blk_addr);

        memcpy(page_address(page), src, 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)
{
        f2fs_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 = f2fs_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);
        memset(dst, 0, PAGE_SIZE);

        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 = GET_SEC_FROM_SEG(sbi, *newseg);
        unsigned int old_zoneno = GET_ZONE_FROM_SEG(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,
                        GET_SEG_FROM_SEC(sbi, hint + 1), *newseg + 1);
                if (segno < GET_SEG_FROM_SEC(sbi, hint + 1))
                        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:
        segno = GET_SEG_FROM_SEC(sbi, secno);
        zoneno = GET_ZONE_FROM_SEC(sbi, secno);

        /* 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_ZONE_FROM_SEG(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);
}

static unsigned int __get_next_segno(struct f2fs_sb_info *sbi, int type)
{
        /* if segs_per_sec is large than 1, we need to keep original policy. */
        if (sbi->segs_per_sec != 1)
                return CURSEG_I(sbi, type)->segno;

        if (test_opt(sbi, NOHEAP) &&
                (type == CURSEG_HOT_DATA || IS_NODESEG(type)))
                return 0;

        if (SIT_I(sbi)->last_victim[ALLOC_NEXT])
                return SIT_I(sbi)->last_victim[ALLOC_NEXT];

        /* find segments from 0 to reuse freed segments */
        if (F2FS_OPTION(sbi).alloc_mode == ALLOC_MODE_REUSE)
                return 0;

        return CURSEG_I(sbi, type)->segno;
}

/*
 * 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;

        segno = __get_next_segno(sbi, type);
        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)
{
        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);

        sum_page = f2fs_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;
        unsigned segno = NULL_SEGNO;
        int i, cnt;
        bool reversed = false;

        /* f2fs_need_SSR() already forces to do this */
        if (v_ops->get_victim(sbi, &segno, BG_GC, type, SSR)) {
                curseg->next_segno = segno;
                return 1;
        }

        /* For node segments, let's do SSR more intensively */
        if (IS_NODESEG(type)) {
                if (type >= CURSEG_WARM_NODE) {
                        reversed = true;
                        i = CURSEG_COLD_NODE;
                } else {
                        i = CURSEG_HOT_NODE;
                }
                cnt = NR_CURSEG_NODE_TYPE;
        } else {
                if (type >= CURSEG_WARM_DATA) {
                        reversed = true;
                        i = CURSEG_COLD_DATA;
                } else {
                        i = CURSEG_HOT_DATA;
                }
                cnt = NR_CURSEG_DATA_TYPE;
        }

        for (; cnt-- > 0; reversed ? i-- : i++) {
                if (i == type)
                        continue;
                if (v_ops->get_victim(sbi, &segno, BG_GC, i, SSR)) {
                        curseg->next_segno = segno;
                        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 (!is_set_ckpt_flags(sbi, CP_CRC_RECOVERY_FLAG) &&
                                        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 (f2fs_need_SSR(sbi) && get_ssr_segment(sbi, type))
                change_curseg(sbi, type);
        else
                new_curseg(sbi, type, false);

        stat_inc_seg_type(sbi, curseg);
}

void f2fs_allocate_new_segments(struct f2fs_sb_info *sbi)
{
        struct curseg_info *curseg;
        unsigned int old_segno;
        int i;

        down_write(&SIT_I(sbi)->sentry_lock);

        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);
        }

        up_write(&SIT_I(sbi)->sentry_lock);
}

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

bool f2fs_exist_trim_candidates(struct f2fs_sb_info *sbi,
                                                struct cp_control *cpc)
{
        __u64 trim_start = cpc->trim_start;
        bool has_candidate = false;

        down_write(&SIT_I(sbi)->sentry_lock);
        for (; cpc->trim_start <= cpc->trim_end; cpc->trim_start++) {
                if (add_discard_addrs(sbi, cpc, true)) {
                        has_candidate = true;
                        break;
                }
        }
        up_write(&SIT_I(sbi)->sentry_lock);

        cpc->trim_start = trim_start;
        return has_candidate;
}

static unsigned int __issue_discard_cmd_range(struct f2fs_sb_info *sbi,
                                        struct discard_policy *dpolicy,
                                        unsigned int start, unsigned int end)
{
        struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
        struct discard_cmd *prev_dc = NULL, *next_dc = NULL;
        struct rb_node **insert_p = NULL, *insert_parent = NULL;
        struct discard_cmd *dc;
        struct blk_plug plug;
        int issued;
        unsigned int trimmed = 0;

next:
        issued = 0;

        mutex_lock(&dcc->cmd_lock);
        if (unlikely(dcc->rbtree_check))
                f2fs_bug_on(sbi, !f2fs_check_rb_tree_consistence(sbi,
                                                                &dcc->root));

        dc = (struct discard_cmd *)f2fs_lookup_rb_tree_ret(&dcc->root,
                                        NULL, start,
                                        (struct rb_entry **)&prev_dc,
                                        (struct rb_entry **)&next_dc,
                                        &insert_p, &insert_parent, true);
        if (!dc)
                dc = next_dc;

        blk_start_plug(&plug);

        while (dc && dc->lstart <= end) {
                struct rb_node *node;
                int err = 0;

                if (dc->len < dpolicy->granularity)
                        goto skip;

                if (dc->state != D_PREP) {
                        list_move_tail(&dc->list, &dcc->fstrim_list);
                        goto skip;
                }

                err = __submit_discard_cmd(sbi, dpolicy, dc, &issued);

                if (issued >= dpolicy->max_requests) {
                        start = dc->lstart + dc->len;

                        if (err)
                                __remove_discard_cmd(sbi, dc);

                        blk_finish_plug(&plug);
                        mutex_unlock(&dcc->cmd_lock);
                        trimmed += __wait_all_discard_cmd(sbi, NULL);
                        congestion_wait(BLK_RW_ASYNC, HZ/50);
                        goto next;
                }
skip:
                node = rb_next(&dc->rb_node);
                if (err)
                        __remove_discard_cmd(sbi, dc);
                dc = rb_entry_safe(node, struct discard_cmd, rb_node);

                if (fatal_signal_pending(current))
                        break;
        }

        blk_finish_plug(&plug);
        mutex_unlock(&dcc->cmd_lock);

        return trimmed;
}

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;
        block_t start_block, end_block;
        struct cp_control cpc;
        struct discard_policy dpolicy;
        unsigned long long trimmed = 0;
        int err = 0;
        bool need_align = test_opt(sbi, LFS) && sbi->segs_per_sec > 1;

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

        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.");
                return -EIO;
        }

        /* 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);
        if (need_align) {
                start_segno = rounddown(start_segno, sbi->segs_per_sec);
                end_segno = roundup(end_segno + 1, sbi->segs_per_sec) - 1;
        }

        cpc.reason = CP_DISCARD;
        cpc.trim_minlen = max_t(__u64, 1, F2FS_BYTES_TO_BLK(range->minlen));
        cpc.trim_start = start_segno;
        cpc.trim_end = end_segno;

        if (sbi->discard_blks == 0)
                goto out;

        mutex_lock(&sbi->gc_mutex);
        err = f2fs_write_checkpoint(sbi, &cpc);
        mutex_unlock(&sbi->gc_mutex);
        if (err)
                goto out;

        /*
         * We filed discard candidates, but actually we don't need to wait for
         * all of them, since they'll be issued in idle time along with runtime
         * discard option. User configuration looks like using runtime discard
         * or periodic fstrim instead of it.
         */
        if (test_opt(sbi, DISCARD))
                goto out;

        start_block = START_BLOCK(sbi, start_segno);
        end_block = START_BLOCK(sbi, end_segno + 1);

        __init_discard_policy(sbi, &dpolicy, DPOLICY_FSTRIM, cpc.trim_minlen);
        trimmed = __issue_discard_cmd_range(sbi, &dpolicy,
                                        start_block, end_block);

        trimmed += __wait_discard_cmd_range(sbi, &dpolicy,
                                        start_block, end_block);
out:
        if (!err)
                range->len = F2FS_BLK_TO_BYTES(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;
}

int f2fs_rw_hint_to_seg_type(enum rw_hint hint)
{
        switch (hint) {
        case WRITE_LIFE_SHORT:
                return CURSEG_HOT_DATA;
        case WRITE_LIFE_EXTREME:
                return CURSEG_COLD_DATA;
        default:
                return CURSEG_WARM_DATA;
        }
}

/* This returns write hints for each segment type. This hints will be
 * passed down to block layer. There are mapping tables which depend on
 * the mount option 'whint_mode'.
 *
 * 1) whint_mode=off. F2FS only passes down WRITE_LIFE_NOT_SET.
 *
 * 2) whint_mode=user-based. F2FS tries to pass down hints given by users.
 *
 * User                  F2FS                     Block
 * ----                  ----                     -----
 *                       META                     WRITE_LIFE_NOT_SET
 *                       HOT_NODE                 "
 *                       WARM_NODE                "
 *                       COLD_NODE                "
 * ioctl(COLD)           COLD_DATA                WRITE_LIFE_EXTREME
 * extension list        "                        "
 *
 * -- buffered io
 * WRITE_LIFE_EXTREME    COLD_DATA                WRITE_LIFE_EXTREME
 * WRITE_LIFE_SHORT      HOT_DATA                 WRITE_LIFE_SHORT
 * WRITE_LIFE_NOT_SET    WARM_DATA                WRITE_LIFE_NOT_SET
 * WRITE_LIFE_NONE       "                        "
 * WRITE_LIFE_MEDIUM     "                        "
 * WRITE_LIFE_LONG       "                        "
 *
 * -- direct io
 * WRITE_LIFE_EXTREME    COLD_DATA                WRITE_LIFE_EXTREME
 * WRITE_LIFE_SHORT      HOT_DATA                 WRITE_LIFE_SHORT
 * WRITE_LIFE_NOT_SET    WARM_DATA                WRITE_LIFE_NOT_SET
 * WRITE_LIFE_NONE       "                        WRITE_LIFE_NONE
 * WRITE_LIFE_MEDIUM     "                        WRITE_LIFE_MEDIUM
 * WRITE_LIFE_LONG       "                        WRITE_LIFE_LONG
 *
 * 3) whint_mode=fs-based. F2FS passes down hints with its policy.
 *
 * User                  F2FS                     Block
 * ----                  ----                     -----
 *                       META                     WRITE_LIFE_MEDIUM;
 *                       HOT_NODE                 WRITE_LIFE_NOT_SET
 *                       WARM_NODE                "
 *                       COLD_NODE                WRITE_LIFE_NONE
 * ioctl(COLD)           COLD_DATA                WRITE_LIFE_EXTREME
 * extension list        "                        "
 *
 * -- buffered io
 * WRITE_LIFE_EXTREME    COLD_DATA                WRITE_LIFE_EXTREME
 * WRITE_LIFE_SHORT      HOT_DATA                 WRITE_LIFE_SHORT
 * WRITE_LIFE_NOT_SET    WARM_DATA                WRITE_LIFE_LONG
 * WRITE_LIFE_NONE       "                        "
 * WRITE_LIFE_MEDIUM     "                        "
 * WRITE_LIFE_LONG       "                        "
 *
 * -- direct io
 * WRITE_LIFE_EXTREME    COLD_DATA                WRITE_LIFE_EXTREME
 * WRITE_LIFE_SHORT      HOT_DATA                 WRITE_LIFE_SHORT
 * WRITE_LIFE_NOT_SET    WARM_DATA                WRITE_LIFE_NOT_SET
 * WRITE_LIFE_NONE       "                        WRITE_LIFE_NONE
 * WRITE_LIFE_MEDIUM     "                        WRITE_LIFE_MEDIUM
 * WRITE_LIFE_LONG       "                        WRITE_LIFE_LONG
 */

enum rw_hint f2fs_io_type_to_rw_hint(struct f2fs_sb_info *sbi,
                                enum page_type type, enum temp_type temp)
{
        if (F2FS_OPTION(sbi).whint_mode == WHINT_MODE_USER) {
                if (type == DATA) {
                        if (temp == WARM)
                                return WRITE_LIFE_NOT_SET;
                        else if (temp == HOT)
                                return WRITE_LIFE_SHORT;
                        else if (temp == COLD)
                                return WRITE_LIFE_EXTREME;
                } else {
                        return WRITE_LIFE_NOT_SET;
                }
        } else if (F2FS_OPTION(sbi).whint_mode == WHINT_MODE_FS) {
                if (type == DATA) {
                        if (temp == WARM)
                                return WRITE_LIFE_LONG;
                        else if (temp == HOT)
                                return WRITE_LIFE_SHORT;
                        else if (temp == COLD)
                                return WRITE_LIFE_EXTREME;
                } else if (type == NODE) {
                        if (temp == WARM || temp == HOT)
                                return WRITE_LIFE_NOT_SET;
                        else if (temp == COLD)
                                return WRITE_LIFE_NONE;
                } else if (type == META) {
                        return WRITE_LIFE_MEDIUM;
                }
        }
        return WRITE_LIFE_NOT_SET;
}

static int __get_segment_type_2(struct f2fs_io_info *fio)
{
        if (fio->type == DATA)
                return CURSEG_HOT_DATA;
        else
                return CURSEG_HOT_NODE;
}

static int __get_segment_type_4(struct f2fs_io_info *fio)
{
        if (fio->type == DATA) {
                struct inode *inode = fio->page->mapping->host;

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

static int __get_segment_type_6(struct f2fs_io_info *fio)
{
        if (fio->type == DATA) {
                struct inode *inode = fio->page->mapping->host;

                if (is_cold_data(fio->page) || file_is_cold(inode))
                        return CURSEG_COLD_DATA;
                if (file_is_hot(inode) ||
                                is_inode_flag_set(inode, FI_HOT_DATA) ||
                                f2fs_is_atomic_file(inode) ||
                                f2fs_is_volatile_file(inode))
                        return CURSEG_HOT_DATA;
                return f2fs_rw_hint_to_seg_type(inode->i_write_hint);
        } else {
                if (IS_DNODE(fio->page))
                        return is_cold_node(fio->page) ? CURSEG_WARM_NODE :
                                                CURSEG_HOT_NODE;
                return CURSEG_COLD_NODE;
        }
}

static int __get_segment_type(struct f2fs_io_info *fio)
{
        int type = 0;

        switch (F2FS_OPTION(fio->sbi).active_logs) {
        case 2:
                type = __get_segment_type_2(fio);
                break;
        case 4:
                type = __get_segment_type_4(fio);
                break;
        case 6:
                type = __get_segment_type_6(fio);
                break;
        default:
                f2fs_bug_on(fio->sbi, true);
        }

        if (IS_HOT(type))
                fio->temp = HOT;
        else if (IS_WARM(type))
                fio->temp = WARM;
        else
                fio->temp = COLD;
        return type;
}

void f2fs_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 f2fs_io_info *fio, bool add_list)
{
        struct sit_info *sit_i = SIT_I(sbi);
        struct curseg_info *curseg = CURSEG_I(sbi, type);

        down_read(&SM_I(sbi)->curseg_lock);

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

        *new_blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);

        f2fs_wait_discard_bio(sbi, *new_blkaddr);

        /*
         * __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);

        /*
         * SIT information should be updated before segment allocation,
         * since SSR needs latest valid block information.
         */
        update_sit_entry(sbi, *new_blkaddr, 1);
        if (GET_SEGNO(sbi, old_blkaddr) != NULL_SEGNO)
                update_sit_entry(sbi, old_blkaddr, -1);

        if (!__has_curseg_space(sbi, type))
                sit_i->s_ops->allocate_segment(sbi, type, false);

        /*
         * segment dirty status should be updated after segment allocation,
         * so we just need to update status only one time after previous
         * segment being closed.
         */
        locate_dirty_segment(sbi, GET_SEGNO(sbi, old_blkaddr));
        locate_dirty_segment(sbi, GET_SEGNO(sbi, *new_blkaddr));

        up_write(&sit_i->sentry_lock);

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

                f2fs_inode_chksum_set(sbi, page);
        }

        if (add_list) {
                struct f2fs_bio_info *io;

                INIT_LIST_HEAD(&fio->list);
                fio->in_list = true;
                fio->retry = false;
                io = sbi->write_io[fio->type] + fio->temp;
                spin_lock(&io->io_lock);
                list_add_tail(&fio->list, &io->io_list);
                spin_unlock(&io->io_lock);
        }

        mutex_unlock(&curseg->curseg_mutex);

        up_read(&SM_I(sbi)->curseg_lock);
}

static void update_device_state(struct f2fs_io_info *fio)
{
        struct f2fs_sb_info *sbi = fio->sbi;
        unsigned int devidx;

        if (!sbi->s_ndevs)
                return;

        devidx = f2fs_target_device_index(sbi, fio->new_blkaddr);

        /* update device state for fsync */
        f2fs_set_dirty_device(sbi, fio->ino, devidx, FLUSH_INO);

        /* update device state for checkpoint */
        if (!f2fs_test_bit(devidx, (char *)&sbi->dirty_device)) {
                spin_lock(&sbi->dev_lock);
                f2fs_set_bit(devidx, (char *)&sbi->dirty_device);
                spin_unlock(&sbi->dev_lock);
        }
}

static void do_write_page(struct f2fs_summary *sum, struct f2fs_io_info *fio)
{
        int type = __get_segment_type(fio);
        bool keep_order = (test_opt(fio->sbi, LFS) && type == CURSEG_COLD_DATA);

        if (keep_order)
                down_read(&fio->sbi->io_order_lock);
reallocate:
        f2fs_allocate_data_block(fio->sbi, fio->page, fio->old_blkaddr,
                        &fio->new_blkaddr, sum, type, fio, true);
        if (GET_SEGNO(fio->sbi, fio->old_blkaddr) != NULL_SEGNO)
                invalidate_mapping_pages(META_MAPPING(fio->sbi),
                                        fio->old_blkaddr, fio->old_blkaddr);

        /* writeout dirty page into bdev */
        f2fs_submit_page_write(fio);
        if (fio->retry) {
                fio->old_blkaddr = fio->new_blkaddr;
                goto reallocate;
        }

        update_device_state(fio);

        if (keep_order)
                up_read(&fio->sbi->io_order_lock);
}

void f2fs_do_write_meta_page(struct f2fs_sb_info *sbi, struct page *page,