[GitHub/exynos8895/android_kernel_samsung_universal8895.git] / fs / f2fs / data.c

/*
 * fs/f2fs/data.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/buffer_head.h>
#include <linux/mpage.h>
#include <linux/aio.h>
#include <linux/writeback.h>
#include <linux/backing-dev.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/prefetch.h>

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

static struct kmem_cache *extent_tree_slab;
static struct kmem_cache *extent_node_slab;

static void f2fs_read_end_io(struct bio *bio, int err)
{
        struct bio_vec *bvec;
        int i;

        bio_for_each_segment_all(bvec, bio, i) {
                struct page *page = bvec->bv_page;

                if (!err) {
                        SetPageUptodate(page);
                } else {
                        ClearPageUptodate(page);
                        SetPageError(page);
                }
                unlock_page(page);
        }
        bio_put(bio);
}

static void f2fs_write_end_io(struct bio *bio, int err)
{
        struct f2fs_sb_info *sbi = bio->bi_private;
        struct bio_vec *bvec;
        int i;

        bio_for_each_segment_all(bvec, bio, i) {
                struct page *page = bvec->bv_page;

                if (unlikely(err)) {
                        set_page_dirty(page);
                        set_bit(AS_EIO, &page->mapping->flags);
                        f2fs_stop_checkpoint(sbi);
                }
                end_page_writeback(page);
                dec_page_count(sbi, F2FS_WRITEBACK);
        }

        if (!get_pages(sbi, F2FS_WRITEBACK) &&
                        !list_empty(&sbi->cp_wait.task_list))
                wake_up(&sbi->cp_wait);

        bio_put(bio);
}

/*
 * Low-level block read/write IO operations.
 */
static struct bio *__bio_alloc(struct f2fs_sb_info *sbi, block_t blk_addr,
                                int npages, bool is_read)
{
        struct bio *bio;

        /* No failure on bio allocation */
        bio = bio_alloc(GFP_NOIO, npages);

        bio->bi_bdev = sbi->sb->s_bdev;
        bio->bi_iter.bi_sector = SECTOR_FROM_BLOCK(blk_addr);
        bio->bi_end_io = is_read ? f2fs_read_end_io : f2fs_write_end_io;
        bio->bi_private = sbi;

        return bio;
}

static void __submit_merged_bio(struct f2fs_bio_info *io)
{
        struct f2fs_io_info *fio = &io->fio;

        if (!io->bio)
                return;

        if (is_read_io(fio->rw))
                trace_f2fs_submit_read_bio(io->sbi->sb, fio, io->bio);
        else
                trace_f2fs_submit_write_bio(io->sbi->sb, fio, io->bio);

        submit_bio(fio->rw, io->bio);
        io->bio = NULL;
}

void f2fs_submit_merged_bio(struct f2fs_sb_info *sbi,
                                enum page_type type, int rw)
{
        enum page_type btype = PAGE_TYPE_OF_BIO(type);
        struct f2fs_bio_info *io;

        io = is_read_io(rw) ? &sbi->read_io : &sbi->write_io[btype];

        down_write(&io->io_rwsem);

        /* change META to META_FLUSH in the checkpoint procedure */
        if (type >= META_FLUSH) {
                io->fio.type = META_FLUSH;
                if (test_opt(sbi, NOBARRIER))
                        io->fio.rw = WRITE_FLUSH | REQ_META | REQ_PRIO;
                else
                        io->fio.rw = WRITE_FLUSH_FUA | REQ_META | REQ_PRIO;
        }
        __submit_merged_bio(io);
        up_write(&io->io_rwsem);
}

/*
 * Fill the locked page with data located in the block address.
 * Return unlocked page.
 */
int f2fs_submit_page_bio(struct f2fs_sb_info *sbi, struct page *page,
                                        struct f2fs_io_info *fio)
{
        struct bio *bio;

        trace_f2fs_submit_page_bio(page, fio);
        f2fs_trace_ios(page, fio, 0);

        /* Allocate a new bio */
        bio = __bio_alloc(sbi, fio->blk_addr, 1, is_read_io(fio->rw));

        if (bio_add_page(bio, page, PAGE_CACHE_SIZE, 0) < PAGE_CACHE_SIZE) {
                bio_put(bio);
                f2fs_put_page(page, 1);
                return -EFAULT;
        }

        submit_bio(fio->rw, bio);
        return 0;
}

void f2fs_submit_page_mbio(struct f2fs_sb_info *sbi, struct page *page,
                                        struct f2fs_io_info *fio)
{
        enum page_type btype = PAGE_TYPE_OF_BIO(fio->type);
        struct f2fs_bio_info *io;
        bool is_read = is_read_io(fio->rw);

        io = is_read ? &sbi->read_io : &sbi->write_io[btype];

        verify_block_addr(sbi, fio->blk_addr);

        down_write(&io->io_rwsem);

        if (!is_read)
                inc_page_count(sbi, F2FS_WRITEBACK);

        if (io->bio && (io->last_block_in_bio != fio->blk_addr - 1 ||
                                                io->fio.rw != fio->rw))
                __submit_merged_bio(io);
alloc_new:
        if (io->bio == NULL) {
                int bio_blocks = MAX_BIO_BLOCKS(sbi);

                io->bio = __bio_alloc(sbi, fio->blk_addr, bio_blocks, is_read);
                io->fio = *fio;
        }

        if (bio_add_page(io->bio, page, PAGE_CACHE_SIZE, 0) <
                                                        PAGE_CACHE_SIZE) {
                __submit_merged_bio(io);
                goto alloc_new;
        }

        io->last_block_in_bio = fio->blk_addr;
        f2fs_trace_ios(page, fio, 0);

        up_write(&io->io_rwsem);
        trace_f2fs_submit_page_mbio(page, fio);
}

/*
 * Lock ordering for the change of data block address:
 * ->data_page
 *  ->node_page
 *    update block addresses in the node page
 */
void set_data_blkaddr(struct dnode_of_data *dn)
{
        struct f2fs_node *rn;
        __le32 *addr_array;
        struct page *node_page = dn->node_page;
        unsigned int ofs_in_node = dn->ofs_in_node;

        f2fs_wait_on_page_writeback(node_page, NODE);

        rn = F2FS_NODE(node_page);

        /* Get physical address of data block */
        addr_array = blkaddr_in_node(rn);
        addr_array[ofs_in_node] = cpu_to_le32(dn->data_blkaddr);
        set_page_dirty(node_page);
}

int reserve_new_block(struct dnode_of_data *dn)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);

        if (unlikely(is_inode_flag_set(F2FS_I(dn->inode), FI_NO_ALLOC)))
                return -EPERM;
        if (unlikely(!inc_valid_block_count(sbi, dn->inode, 1)))
                return -ENOSPC;

        trace_f2fs_reserve_new_block(dn->inode, dn->nid, dn->ofs_in_node);

        dn->data_blkaddr = NEW_ADDR;
        set_data_blkaddr(dn);
        mark_inode_dirty(dn->inode);
        sync_inode_page(dn);
        return 0;
}

int f2fs_reserve_block(struct dnode_of_data *dn, pgoff_t index)
{
        bool need_put = dn->inode_page ? false : true;
        int err;

        err = get_dnode_of_data(dn, index, ALLOC_NODE);
        if (err)
                return err;

        if (dn->data_blkaddr == NULL_ADDR)
                err = reserve_new_block(dn);
        if (err || need_put)
                f2fs_put_dnode(dn);
        return err;
}

static void f2fs_map_bh(struct super_block *sb, pgoff_t pgofs,
                        struct extent_info *ei, struct buffer_head *bh_result)
{
        unsigned int blkbits = sb->s_blocksize_bits;
        size_t max_size = bh_result->b_size;
        size_t mapped_size;

        clear_buffer_new(bh_result);
        map_bh(bh_result, sb, ei->blk + pgofs - ei->fofs);
        mapped_size = (ei->fofs + ei->len - pgofs) << blkbits;
        bh_result->b_size = min(max_size, mapped_size);
}

static bool lookup_extent_info(struct inode *inode, pgoff_t pgofs,
                                                        struct extent_info *ei)
{
        struct f2fs_inode_info *fi = F2FS_I(inode);
        pgoff_t start_fofs, end_fofs;
        block_t start_blkaddr;

        read_lock(&fi->ext_lock);
        if (fi->ext.len == 0) {
                read_unlock(&fi->ext_lock);
                return false;
        }

        stat_inc_total_hit(inode->i_sb);

        start_fofs = fi->ext.fofs;
        end_fofs = fi->ext.fofs + fi->ext.len - 1;
        start_blkaddr = fi->ext.blk;

        if (pgofs >= start_fofs && pgofs <= end_fofs) {
                *ei = fi->ext;
                stat_inc_read_hit(inode->i_sb);
                read_unlock(&fi->ext_lock);
                return true;
        }
        read_unlock(&fi->ext_lock);
        return false;
}

static bool update_extent_info(struct inode *inode, pgoff_t fofs,
                                                                block_t blkaddr)
{
        struct f2fs_inode_info *fi = F2FS_I(inode);
        pgoff_t start_fofs, end_fofs;
        block_t start_blkaddr, end_blkaddr;
        int need_update = true;

        write_lock(&fi->ext_lock);

        start_fofs = fi->ext.fofs;
        end_fofs = fi->ext.fofs + fi->ext.len - 1;
        start_blkaddr = fi->ext.blk;
        end_blkaddr = fi->ext.blk + fi->ext.len - 1;

        /* Drop and initialize the matched extent */
        if (fi->ext.len == 1 && fofs == start_fofs)
                fi->ext.len = 0;

        /* Initial extent */
        if (fi->ext.len == 0) {
                if (blkaddr != NULL_ADDR) {
                        fi->ext.fofs = fofs;
                        fi->ext.blk = blkaddr;
                        fi->ext.len = 1;
                }
                goto end_update;
        }

        /* Front merge */
        if (fofs == start_fofs - 1 && blkaddr == start_blkaddr - 1) {
                fi->ext.fofs--;
                fi->ext.blk--;
                fi->ext.len++;
                goto end_update;
        }

        /* Back merge */
        if (fofs == end_fofs + 1 && blkaddr == end_blkaddr + 1) {
                fi->ext.len++;
                goto end_update;
        }

        /* Split the existing extent */
        if (fi->ext.len > 1 &&
                fofs >= start_fofs && fofs <= end_fofs) {
                if ((end_fofs - fofs) < (fi->ext.len >> 1)) {
                        fi->ext.len = fofs - start_fofs;
                } else {
                        fi->ext.fofs = fofs + 1;
                        fi->ext.blk = start_blkaddr + fofs - start_fofs + 1;
                        fi->ext.len -= fofs - start_fofs + 1;
                }
        } else {
                need_update = false;
        }

        /* Finally, if the extent is very fragmented, let's drop the cache. */
        if (fi->ext.len < F2FS_MIN_EXTENT_LEN) {
                fi->ext.len = 0;
                set_inode_flag(fi, FI_NO_EXTENT);
                need_update = true;
        }
end_update:
        write_unlock(&fi->ext_lock);
        return need_update;
}

static struct extent_node *__attach_extent_node(struct f2fs_sb_info *sbi,
                                struct extent_tree *et, struct extent_info *ei,
                                struct rb_node *parent, struct rb_node **p)
{
        struct extent_node *en;

        en = kmem_cache_alloc(extent_node_slab, GFP_ATOMIC);
        if (!en)
                return NULL;

        en->ei = *ei;
        INIT_LIST_HEAD(&en->list);

        rb_link_node(&en->rb_node, parent, p);
        rb_insert_color(&en->rb_node, &et->root);
        et->count++;
        atomic_inc(&sbi->total_ext_node);
        return en;
}

static void __detach_extent_node(struct f2fs_sb_info *sbi,
                                struct extent_tree *et, struct extent_node *en)
{
        rb_erase(&en->rb_node, &et->root);
        et->count--;
        atomic_dec(&sbi->total_ext_node);

        if (et->cached_en == en)
                et->cached_en = NULL;
}

static struct extent_tree *__find_extent_tree(struct f2fs_sb_info *sbi,
                                                        nid_t ino)
{
        struct extent_tree *et;

        down_read(&sbi->extent_tree_lock);
        et = radix_tree_lookup(&sbi->extent_tree_root, ino);
        if (!et) {
                up_read(&sbi->extent_tree_lock);
                return NULL;
        }
        atomic_inc(&et->refcount);
        up_read(&sbi->extent_tree_lock);

        return et;
}

static struct extent_tree *__grab_extent_tree(struct inode *inode)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et;
        nid_t ino = inode->i_ino;

        down_write(&sbi->extent_tree_lock);
        et = radix_tree_lookup(&sbi->extent_tree_root, ino);
        if (!et) {
                et = f2fs_kmem_cache_alloc(extent_tree_slab, GFP_NOFS);
                f2fs_radix_tree_insert(&sbi->extent_tree_root, ino, et);
                memset(et, 0, sizeof(struct extent_tree));
                et->ino = ino;
                et->root = RB_ROOT;
                et->cached_en = NULL;
                rwlock_init(&et->lock);
                atomic_set(&et->refcount, 0);
                et->count = 0;
                sbi->total_ext_tree++;
        }
        atomic_inc(&et->refcount);
        up_write(&sbi->extent_tree_lock);

        return et;
}

static struct extent_node *__lookup_extent_tree(struct extent_tree *et,
                                                        unsigned int fofs)
{
        struct rb_node *node = et->root.rb_node;
        struct extent_node *en;

        if (et->cached_en) {
                struct extent_info *cei = &et->cached_en->ei;

                if (cei->fofs <= fofs && cei->fofs + cei->len > fofs)
                        return et->cached_en;
        }

        while (node) {
                en = rb_entry(node, struct extent_node, rb_node);

                if (fofs < en->ei.fofs) {
                        node = node->rb_left;
                } else if (fofs >= en->ei.fofs + en->ei.len) {
                        node = node->rb_right;
                } else {
                        et->cached_en = en;
                        return en;
                }
        }
        return NULL;
}

static struct extent_node *__try_back_merge(struct f2fs_sb_info *sbi,
                                struct extent_tree *et, struct extent_node *en)
{
        struct extent_node *prev;
        struct rb_node *node;

        node = rb_prev(&en->rb_node);
        if (!node)
                return NULL;

        prev = rb_entry(node, struct extent_node, rb_node);
        if (__is_back_mergeable(&en->ei, &prev->ei)) {
                en->ei.fofs = prev->ei.fofs;
                en->ei.blk = prev->ei.blk;
                en->ei.len += prev->ei.len;
                __detach_extent_node(sbi, et, prev);
                return prev;
        }
        return NULL;
}

static struct extent_node *__try_front_merge(struct f2fs_sb_info *sbi,
                                struct extent_tree *et, struct extent_node *en)
{
        struct extent_node *next;
        struct rb_node *node;

        node = rb_next(&en->rb_node);
        if (!node)
                return NULL;

        next = rb_entry(node, struct extent_node, rb_node);
        if (__is_front_mergeable(&en->ei, &next->ei)) {
                en->ei.len += next->ei.len;
                __detach_extent_node(sbi, et, next);
                return next;
        }
        return NULL;
}

static struct extent_node *__insert_extent_tree(struct f2fs_sb_info *sbi,
                                struct extent_tree *et, struct extent_info *ei,
                                struct extent_node **den)
{
        struct rb_node **p = &et->root.rb_node;
        struct rb_node *parent = NULL;
        struct extent_node *en;

        while (*p) {
                parent = *p;
                en = rb_entry(parent, struct extent_node, rb_node);

                if (ei->fofs < en->ei.fofs) {
                        if (__is_front_mergeable(ei, &en->ei)) {
                                f2fs_bug_on(sbi, !den);
                                en->ei.fofs = ei->fofs;
                                en->ei.blk = ei->blk;
                                en->ei.len += ei->len;
                                *den = __try_back_merge(sbi, et, en);
                                return en;
                        }
                        p = &(*p)->rb_left;
                } else if (ei->fofs >= en->ei.fofs + en->ei.len) {
                        if (__is_back_mergeable(ei, &en->ei)) {
                                f2fs_bug_on(sbi, !den);
                                en->ei.len += ei->len;
                                *den = __try_front_merge(sbi, et, en);
                                return en;
                        }
                        p = &(*p)->rb_right;
                } else {
                        f2fs_bug_on(sbi, 1);
                }
        }

        return __attach_extent_node(sbi, et, ei, parent, p);
}

static unsigned int __free_extent_tree(struct f2fs_sb_info *sbi,
                                        struct extent_tree *et, bool free_all)
{
        struct rb_node *node, *next;
        struct extent_node *en;
        unsigned int count = et->count;

        node = rb_first(&et->root);
        while (node) {
                next = rb_next(node);
                en = rb_entry(node, struct extent_node, rb_node);

                if (free_all) {
                        spin_lock(&sbi->extent_lock);
                        if (!list_empty(&en->list))
                                list_del_init(&en->list);
                        spin_unlock(&sbi->extent_lock);
                }

                if (free_all || list_empty(&en->list)) {
                        __detach_extent_node(sbi, et, en);
                        kmem_cache_free(extent_node_slab, en);
                }
                node = next;
        }

        return count - et->count;
}

static void f2fs_init_extent_tree(struct inode *inode,
                                                struct f2fs_extent *i_ext)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et;
        struct extent_node *en;
        struct extent_info ei;

        if (le32_to_cpu(i_ext->len) < F2FS_MIN_EXTENT_LEN)
                return;

        et = __grab_extent_tree(inode);

        write_lock(&et->lock);
        if (et->count)
                goto out;

        set_extent_info(&ei, le32_to_cpu(i_ext->fofs),
                le32_to_cpu(i_ext->blk), le32_to_cpu(i_ext->len));

        en = __insert_extent_tree(sbi, et, &ei, NULL);
        if (en) {
                et->cached_en = en;

                spin_lock(&sbi->extent_lock);
                list_add_tail(&en->list, &sbi->extent_list);
                spin_unlock(&sbi->extent_lock);
        }
out:
        write_unlock(&et->lock);
        atomic_dec(&et->refcount);
}

static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
                                                        struct extent_info *ei)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et;
        struct extent_node *en;

        trace_f2fs_lookup_extent_tree_start(inode, pgofs);

        et = __find_extent_tree(sbi, inode->i_ino);
        if (!et)
                return false;

        read_lock(&et->lock);
        en = __lookup_extent_tree(et, pgofs);
        if (en) {
                *ei = en->ei;
                spin_lock(&sbi->extent_lock);
                if (!list_empty(&en->list))
                        list_move_tail(&en->list, &sbi->extent_list);
                spin_unlock(&sbi->extent_lock);
                stat_inc_read_hit(sbi->sb);
        }
        stat_inc_total_hit(sbi->sb);
        read_unlock(&et->lock);

        trace_f2fs_lookup_extent_tree_end(inode, pgofs, en);

        atomic_dec(&et->refcount);
        return en ? true : false;
}

static void f2fs_update_extent_tree(struct inode *inode, pgoff_t fofs,
                                                        block_t blkaddr)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et;
        struct extent_node *en = NULL, *en1 = NULL, *en2 = NULL, *en3 = NULL;
        struct extent_node *den = NULL;
        struct extent_info ei, dei;
        unsigned int endofs;

        trace_f2fs_update_extent_tree(inode, fofs, blkaddr);

        et = __grab_extent_tree(inode);

        write_lock(&et->lock);

        /* 1. lookup and remove existing extent info in cache */
        en = __lookup_extent_tree(et, fofs);
        if (!en)
                goto update_extent;

        dei = en->ei;
        __detach_extent_node(sbi, et, en);

        /* 2. if extent can be split more, split and insert the left part */
        if (dei.len > 1) {
                /*  insert left part of split extent into cache */
                if (fofs - dei.fofs >= F2FS_MIN_EXTENT_LEN) {
                        set_extent_info(&ei, dei.fofs, dei.blk,
                                                        fofs - dei.fofs);
                        en1 = __insert_extent_tree(sbi, et, &ei, NULL);
                }

                /* insert right part of split extent into cache */
                endofs = dei.fofs + dei.len - 1;
                if (endofs - fofs >= F2FS_MIN_EXTENT_LEN) {
                        set_extent_info(&ei, fofs + 1,
                                fofs - dei.fofs + dei.blk, endofs - fofs);
                        en2 = __insert_extent_tree(sbi, et, &ei, NULL);
                }
        }

update_extent:
        /* 3. update extent in extent cache */
        if (blkaddr) {
                set_extent_info(&ei, fofs, blkaddr, 1);
                en3 = __insert_extent_tree(sbi, et, &ei, &den);
        }

        /* 4. update in global extent list */
        spin_lock(&sbi->extent_lock);
        if (en && !list_empty(&en->list))
                list_del(&en->list);
        /*
         * en1 and en2 split from en, they will become more and more smaller
         * fragments after splitting several times. So if the length is smaller
         * than F2FS_MIN_EXTENT_LEN, we will not add them into extent tree.
         */
        if (en1)
                list_add_tail(&en1->list, &sbi->extent_list);
        if (en2)
                list_add_tail(&en2->list, &sbi->extent_list);
        if (en3) {
                if (list_empty(&en3->list))
                        list_add_tail(&en3->list, &sbi->extent_list);
                else
                        list_move_tail(&en3->list, &sbi->extent_list);
        }
        if (den && !list_empty(&den->list))
                list_del(&den->list);
        spin_unlock(&sbi->extent_lock);

        /* 5. release extent node */
        if (en)
                kmem_cache_free(extent_node_slab, en);
        if (den)
                kmem_cache_free(extent_node_slab, den);

        write_unlock(&et->lock);
        atomic_dec(&et->refcount);
}

void f2fs_preserve_extent_tree(struct inode *inode)
{
        struct extent_tree *et;
        struct extent_info *ext = &F2FS_I(inode)->ext;
        bool sync = false;

        if (!test_opt(F2FS_I_SB(inode), EXTENT_CACHE))
                return;

        et = __find_extent_tree(F2FS_I_SB(inode), inode->i_ino);
        if (!et) {
                if (ext->len) {
                        ext->len = 0;
                        update_inode_page(inode);
                }
                return;
        }

        read_lock(&et->lock);
        if (et->count) {
                struct extent_node *en;

                if (et->cached_en) {
                        en = et->cached_en;
                } else {
                        struct rb_node *node = rb_first(&et->root);

                        if (!node)
                                node = rb_last(&et->root);
                        en = rb_entry(node, struct extent_node, rb_node);
                }

                if (__is_extent_same(ext, &en->ei))
                        goto out;

                *ext = en->ei;
                sync = true;
        } else if (ext->len) {
                ext->len = 0;
                sync = true;
        }
out:
        read_unlock(&et->lock);
        atomic_dec(&et->refcount);

        if (sync)
                update_inode_page(inode);
}

void f2fs_shrink_extent_tree(struct f2fs_sb_info *sbi, int nr_shrink)
{
        struct extent_tree *treevec[EXT_TREE_VEC_SIZE];
        struct extent_node *en, *tmp;
        unsigned long ino = F2FS_ROOT_INO(sbi);
        struct radix_tree_iter iter;
        void **slot;
        unsigned int found;
        unsigned int node_cnt = 0, tree_cnt = 0;

        if (!test_opt(sbi, EXTENT_CACHE))
                return;

        if (available_free_memory(sbi, EXTENT_CACHE))
                return;

        spin_lock(&sbi->extent_lock);
        list_for_each_entry_safe(en, tmp, &sbi->extent_list, list) {
                if (!nr_shrink--)
                        break;
                list_del_init(&en->list);
        }
        spin_unlock(&sbi->extent_lock);

        down_read(&sbi->extent_tree_lock);
        while ((found = radix_tree_gang_lookup(&sbi->extent_tree_root,
                                (void **)treevec, ino, EXT_TREE_VEC_SIZE))) {
                unsigned i;

                ino = treevec[found - 1]->ino + 1;
                for (i = 0; i < found; i++) {
                        struct extent_tree *et = treevec[i];

                        atomic_inc(&et->refcount);
                        write_lock(&et->lock);
                        node_cnt += __free_extent_tree(sbi, et, false);
                        write_unlock(&et->lock);
                        atomic_dec(&et->refcount);
                }
        }
        up_read(&sbi->extent_tree_lock);

        down_write(&sbi->extent_tree_lock);
        radix_tree_for_each_slot(slot, &sbi->extent_tree_root, &iter,
                                                        F2FS_ROOT_INO(sbi)) {
                struct extent_tree *et = (struct extent_tree *)*slot;

                if (!atomic_read(&et->refcount) && !et->count) {
                        radix_tree_delete(&sbi->extent_tree_root, et->ino);
                        kmem_cache_free(extent_tree_slab, et);
                        sbi->total_ext_tree--;
                        tree_cnt++;
                }
        }
        up_write(&sbi->extent_tree_lock);

        trace_f2fs_shrink_extent_tree(sbi, node_cnt, tree_cnt);
}

void f2fs_destroy_extent_tree(struct inode *inode)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct extent_tree *et;
        unsigned int node_cnt = 0;

        if (!test_opt(sbi, EXTENT_CACHE))
                return;

        et = __find_extent_tree(sbi, inode->i_ino);
        if (!et)
                goto out;

        /* free all extent info belong to this extent tree */
        write_lock(&et->lock);
        node_cnt = __free_extent_tree(sbi, et, true);
        write_unlock(&et->lock);

        atomic_dec(&et->refcount);

        /* try to find and delete extent tree entry in radix tree */
        down_write(&sbi->extent_tree_lock);
        et = radix_tree_lookup(&sbi->extent_tree_root, inode->i_ino);
        if (!et) {
                up_write(&sbi->extent_tree_lock);
                goto out;
        }
        f2fs_bug_on(sbi, atomic_read(&et->refcount) || et->count);
        radix_tree_delete(&sbi->extent_tree_root, inode->i_ino);
        kmem_cache_free(extent_tree_slab, et);
        sbi->total_ext_tree--;
        up_write(&sbi->extent_tree_lock);
out:
        trace_f2fs_destroy_extent_tree(inode, node_cnt);
        return;
}

void f2fs_init_extent_cache(struct inode *inode, struct f2fs_extent *i_ext)
{
        if (test_opt(F2FS_I_SB(inode), EXTENT_CACHE))
                f2fs_init_extent_tree(inode, i_ext);

        write_lock(&F2FS_I(inode)->ext_lock);
        get_extent_info(&F2FS_I(inode)->ext, *i_ext);
        write_unlock(&F2FS_I(inode)->ext_lock);
}

static bool f2fs_lookup_extent_cache(struct inode *inode, pgoff_t pgofs,
                                                        struct extent_info *ei)
{
        if (is_inode_flag_set(F2FS_I(inode), FI_NO_EXTENT))
                return false;

        if (test_opt(F2FS_I_SB(inode), EXTENT_CACHE))
                return f2fs_lookup_extent_tree(inode, pgofs, ei);

        return lookup_extent_info(inode, pgofs, ei);
}

void f2fs_update_extent_cache(struct dnode_of_data *dn)
{
        struct f2fs_inode_info *fi = F2FS_I(dn->inode);
        pgoff_t fofs;

        f2fs_bug_on(F2FS_I_SB(dn->inode), dn->data_blkaddr == NEW_ADDR);

        if (is_inode_flag_set(fi, FI_NO_EXTENT))
                return;

        fofs = start_bidx_of_node(ofs_of_node(dn->node_page), fi) +
                                                        dn->ofs_in_node;

        if (test_opt(F2FS_I_SB(dn->inode), EXTENT_CACHE))
                return f2fs_update_extent_tree(dn->inode, fofs,
                                                        dn->data_blkaddr);

        if (update_extent_info(dn->inode, fofs, dn->data_blkaddr))
                sync_inode_page(dn);
}

struct page *find_data_page(struct inode *inode, pgoff_t index, bool sync)
{
        struct address_space *mapping = inode->i_mapping;
        struct dnode_of_data dn;
        struct page *page;
        struct extent_info ei;
        int err;
        struct f2fs_io_info fio = {
                .type = DATA,
                .rw = sync ? READ_SYNC : READA,
        };

        /*
         * If sync is false, it needs to check its block allocation.
         * This is need and triggered by two flows:
         *   gc and truncate_partial_data_page.
         */
        if (!sync)
                goto search;

        page = find_get_page(mapping, index);
        if (page && PageUptodate(page))
                return page;
        f2fs_put_page(page, 0);
search:
        if (f2fs_lookup_extent_cache(inode, index, &ei)) {
                dn.data_blkaddr = ei.blk + index - ei.fofs;
                goto got_it;
        }

        set_new_dnode(&dn, inode, NULL, NULL, 0);
        err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
        if (err)
                return ERR_PTR(err);
        f2fs_put_dnode(&dn);

        if (dn.data_blkaddr == NULL_ADDR)
                return ERR_PTR(-ENOENT);

        /* By fallocate(), there is no cached page, but with NEW_ADDR */
        if (unlikely(dn.data_blkaddr == NEW_ADDR))
                return ERR_PTR(-EINVAL);

got_it:
        page = grab_cache_page(mapping, index);
        if (!page)
                return ERR_PTR(-ENOMEM);

        if (PageUptodate(page)) {
                unlock_page(page);
                return page;
        }

        fio.blk_addr = dn.data_blkaddr;
        err = f2fs_submit_page_bio(F2FS_I_SB(inode), page, &fio);
        if (err)
                return ERR_PTR(err);

        if (sync) {
                wait_on_page_locked(page);
                if (unlikely(!PageUptodate(page))) {
                        f2fs_put_page(page, 0);
                        return ERR_PTR(-EIO);
                }
        }
        return page;
}

/*
 * If it tries to access a hole, return an error.
 * Because, the callers, functions in dir.c and GC, should be able to know
 * whether this page exists or not.
 */
struct page *get_lock_data_page(struct inode *inode, pgoff_t index)
{
        struct address_space *mapping = inode->i_mapping;
        struct dnode_of_data dn;
        struct page *page;
        struct extent_info ei;
        int err;
        struct f2fs_io_info fio = {
                .type = DATA,
                .rw = READ_SYNC,
        };
repeat:
        page = grab_cache_page(mapping, index);
        if (!page)
                return ERR_PTR(-ENOMEM);

        if (f2fs_lookup_extent_cache(inode, index, &ei)) {
                dn.data_blkaddr = ei.blk + index - ei.fofs;
                goto got_it;
        }

        set_new_dnode(&dn, inode, NULL, NULL, 0);
        err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
        if (err) {
                f2fs_put_page(page, 1);
                return ERR_PTR(err);
        }
        f2fs_put_dnode(&dn);

        if (unlikely(dn.data_blkaddr == NULL_ADDR)) {
                f2fs_put_page(page, 1);
                return ERR_PTR(-ENOENT);
        }

got_it:
        if (PageUptodate(page))
                return page;

        /*
         * A new dentry page is allocated but not able to be written, since its
         * new inode page couldn't be allocated due to -ENOSPC.
         * In such the case, its blkaddr can be remained as NEW_ADDR.
         * see, f2fs_add_link -> get_new_data_page -> init_inode_metadata.
         */
        if (dn.data_blkaddr == NEW_ADDR) {
                zero_user_segment(page, 0, PAGE_CACHE_SIZE);
                SetPageUptodate(page);
                return page;
        }

        fio.blk_addr = dn.data_blkaddr;
        err = f2fs_submit_page_bio(F2FS_I_SB(inode), page, &fio);
        if (err)
                return ERR_PTR(err);

        lock_page(page);
        if (unlikely(!PageUptodate(page))) {
                f2fs_put_page(page, 1);
                return ERR_PTR(-EIO);
        }
        if (unlikely(page->mapping != mapping)) {
                f2fs_put_page(page, 1);
                goto repeat;
        }
        return page;
}

/*
 * Caller ensures that this data page is never allocated.
 * A new zero-filled data page is allocated in the page cache.
 *
 * Also, caller should grab and release a rwsem by calling f2fs_lock_op() and
 * f2fs_unlock_op().
 * Note that, ipage is set only by make_empty_dir.
 */
struct page *get_new_data_page(struct inode *inode,
                struct page *ipage, pgoff_t index, bool new_i_size)
{
        struct address_space *mapping = inode->i_mapping;
        struct page *page;
        struct dnode_of_data dn;
        int err;

        set_new_dnode(&dn, inode, ipage, NULL, 0);
        err = f2fs_reserve_block(&dn, index);
        if (err)
                return ERR_PTR(err);
repeat:
        page = grab_cache_page(mapping, index);
        if (!page) {
                err = -ENOMEM;
                goto put_err;
        }

        if (PageUptodate(page))
                return page;

        if (dn.data_blkaddr == NEW_ADDR) {
                zero_user_segment(page, 0, PAGE_CACHE_SIZE);
                SetPageUptodate(page);
        } else {
                struct f2fs_io_info fio = {
                        .type = DATA,
                        .rw = READ_SYNC,
                        .blk_addr = dn.data_blkaddr,
                };
                err = f2fs_submit_page_bio(F2FS_I_SB(inode), page, &fio);
                if (err)
                        goto put_err;

                lock_page(page);
                if (unlikely(!PageUptodate(page))) {
                        f2fs_put_page(page, 1);
                        err = -EIO;
                        goto put_err;
                }
                if (unlikely(page->mapping != mapping)) {
                        f2fs_put_page(page, 1);
                        goto repeat;
                }
        }

        if (new_i_size &&
                i_size_read(inode) < ((index + 1) << PAGE_CACHE_SHIFT)) {
                i_size_write(inode, ((index + 1) << PAGE_CACHE_SHIFT));
                /* Only the directory inode sets new_i_size */
                set_inode_flag(F2FS_I(inode), FI_UPDATE_DIR);
        }
        return page;

put_err:
        f2fs_put_dnode(&dn);
        return ERR_PTR(err);
}

static int __allocate_data_block(struct dnode_of_data *dn)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);
        struct f2fs_inode_info *fi = F2FS_I(dn->inode);
        struct f2fs_summary sum;
        struct node_info ni;
        int seg = CURSEG_WARM_DATA;
        pgoff_t fofs;

        if (unlikely(is_inode_flag_set(F2FS_I(dn->inode), FI_NO_ALLOC)))
                return -EPERM;

        dn->data_blkaddr = datablock_addr(dn->node_page, dn->ofs_in_node);
        if (dn->data_blkaddr == NEW_ADDR)
                goto alloc;

        if (unlikely(!inc_valid_block_count(sbi, dn->inode, 1)))
                return -ENOSPC;

alloc:
        get_node_info(sbi, dn->nid, &ni);
        set_summary(&sum, dn->nid, dn->ofs_in_node, ni.version);

        if (dn->ofs_in_node == 0 && dn->inode_page == dn->node_page)
                seg = CURSEG_DIRECT_IO;

        allocate_data_block(sbi, NULL, dn->data_blkaddr, &dn->data_blkaddr,
                                                                &sum, seg);

        /* direct IO doesn't use extent cache to maximize the performance */
        set_data_blkaddr(dn);

        /* update i_size */
        fofs = start_bidx_of_node(ofs_of_node(dn->node_page), fi) +
                                                        dn->ofs_in_node;
        if (i_size_read(dn->inode) < ((fofs + 1) << PAGE_CACHE_SHIFT))
                i_size_write(dn->inode, ((fofs + 1) << PAGE_CACHE_SHIFT));

        return 0;
}

static void __allocate_data_blocks(struct inode *inode, loff_t offset,
                                                        size_t count)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct dnode_of_data dn;
        u64 start = F2FS_BYTES_TO_BLK(offset);
        u64 len = F2FS_BYTES_TO_BLK(count);
        bool allocated;
        u64 end_offset;

        while (len) {
                f2fs_balance_fs(sbi);
                f2fs_lock_op(sbi);

                /* When reading holes, we need its node page */
                set_new_dnode(&dn, inode, NULL, NULL, 0);
                if (get_dnode_of_data(&dn, start, ALLOC_NODE))
                        goto out;

                allocated = false;
                end_offset = ADDRS_PER_PAGE(dn.node_page, F2FS_I(inode));

                while (dn.ofs_in_node < end_offset && len) {
                        block_t blkaddr;

                        blkaddr = datablock_addr(dn.node_page, dn.ofs_in_node);
                        if (blkaddr == NULL_ADDR || blkaddr == NEW_ADDR) {
                                if (__allocate_data_block(&dn))
                                        goto sync_out;
                                allocated = true;
                        }
                        len--;
                        start++;
                        dn.ofs_in_node++;
                }

                if (allocated)
                        sync_inode_page(&dn);

                f2fs_put_dnode(&dn);
                f2fs_unlock_op(sbi);
        }
        return;

sync_out:
        if (allocated)
                sync_inode_page(&dn);
        f2fs_put_dnode(&dn);
out:
        f2fs_unlock_op(sbi);
        return;
}

/*
 * get_data_block() now supported readahead/bmap/rw direct_IO with mapped bh.
 * If original data blocks are allocated, then give them to blockdev.
 * Otherwise,
 *     a. preallocate requested block addresses
 *     b. do not use extent cache for better performance
 *     c. give the block addresses to blockdev
 */
static int __get_data_block(struct inode *inode, sector_t iblock,
                        struct buffer_head *bh_result, int create, bool fiemap)
{
        unsigned int blkbits = inode->i_sb->s_blocksize_bits;
        unsigned maxblocks = bh_result->b_size >> blkbits;
        struct dnode_of_data dn;
        int mode = create ? ALLOC_NODE : LOOKUP_NODE_RA;
        pgoff_t pgofs, end_offset;
        int err = 0, ofs = 1;
        struct extent_info ei;
        bool allocated = false;

        /* Get the page offset from the block offset(iblock) */
        pgofs = (pgoff_t)(iblock >> (PAGE_CACHE_SHIFT - blkbits));

        if (f2fs_lookup_extent_cache(inode, pgofs, &ei)) {
                f2fs_map_bh(inode->i_sb, pgofs, &ei, bh_result);
                goto out;
        }

        if (create)
                f2fs_lock_op(F2FS_I_SB(inode));

        /* When reading holes, we need its node page */
        set_new_dnode(&dn, inode, NULL, NULL, 0);
        err = get_dnode_of_data(&dn, pgofs, mode);
        if (err) {
                if (err == -ENOENT)
                        err = 0;
                goto unlock_out;
        }
        if (dn.data_blkaddr == NEW_ADDR && !fiemap)
                goto put_out;

        if (dn.data_blkaddr != NULL_ADDR) {
                clear_buffer_new(bh_result);
                map_bh(bh_result, inode->i_sb, dn.data_blkaddr);
        } else if (create) {
                err = __allocate_data_block(&dn);
                if (err)
                        goto put_out;
                allocated = true;
                set_buffer_new(bh_result);
                map_bh(bh_result, inode->i_sb, dn.data_blkaddr);
        } else {
                goto put_out;
        }

        end_offset = ADDRS_PER_PAGE(dn.node_page, F2FS_I(inode));
        bh_result->b_size = (((size_t)1) << blkbits);
        dn.ofs_in_node++;
        pgofs++;

get_next:
        if (dn.ofs_in_node >= end_offset) {
                if (allocated)
                        sync_inode_page(&dn);
                allocated = false;
                f2fs_put_dnode(&dn);

                set_new_dnode(&dn, inode, NULL, NULL, 0);
                err = get_dnode_of_data(&dn, pgofs, mode);
                if (err) {
                        if (err == -ENOENT)
                                err = 0;
                        goto unlock_out;
                }
                if (dn.data_blkaddr == NEW_ADDR && !fiemap)
                        goto put_out;

                end_offset = ADDRS_PER_PAGE(dn.node_page, F2FS_I(inode));
        }

        if (maxblocks > (bh_result->b_size >> blkbits)) {
                block_t blkaddr = datablock_addr(dn.node_page, dn.ofs_in_node);
                if (blkaddr == NULL_ADDR && create) {
                        err = __allocate_data_block(&dn);
                        if (err)
                                goto sync_out;
                        allocated = true;
                        set_buffer_new(bh_result);
                        blkaddr = dn.data_blkaddr;
                }
                /* Give more consecutive addresses for the readahead */
                if (blkaddr == (bh_result->b_blocknr + ofs)) {
                        ofs++;
                        dn.ofs_in_node++;
                        pgofs++;
                        bh_result->b_size += (((size_t)1) << blkbits);
                        goto get_next;
                }
        }
sync_out:
        if (allocated)
                sync_inode_page(&dn);
put_out:
        f2fs_put_dnode(&dn);
unlock_out:
        if (create)
                f2fs_unlock_op(F2FS_I_SB(inode));
out:
        trace_f2fs_get_data_block(inode, iblock, bh_result, err);
        return err;
}

static int get_data_block(struct inode *inode, sector_t iblock,
                        struct buffer_head *bh_result, int create)
{
        return __get_data_block(inode, iblock, bh_result, create, false);
}

static int get_data_block_fiemap(struct inode *inode, sector_t iblock,
                        struct buffer_head *bh_result, int create)
{
        return __get_data_block(inode, iblock, bh_result, create, true);
}

int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                u64 start, u64 len)
{
        return generic_block_fiemap(inode, fieinfo,
                                start, len, get_data_block_fiemap);
}

static int f2fs_read_data_page(struct file *file, struct page *page)
{
        struct inode *inode = page->mapping->host;
        int ret = -EAGAIN;

        trace_f2fs_readpage(page, DATA);

        /* If the file has inline data, try to read it directly */
        if (f2fs_has_inline_data(inode))
                ret = f2fs_read_inline_data(inode, page);
        if (ret == -EAGAIN)
                ret = mpage_readpage(page, get_data_block);

        return ret;
}

static int f2fs_read_data_pages(struct file *file,
                        struct address_space *mapping,
                        struct list_head *pages, unsigned nr_pages)
{
        struct inode *inode = file->f_mapping->host;

        /* If the file has inline data, skip readpages */
        if (f2fs_has_inline_data(inode))
                return 0;

        return mpage_readpages(mapping, pages, nr_pages, get_data_block);
}

int do_write_data_page(struct page *page, struct f2fs_io_info *fio)
{
        struct inode *inode = page->mapping->host;
        struct dnode_of_data dn;
        int err = 0;

        set_new_dnode(&dn, inode, NULL, NULL, 0);
        err = get_dnode_of_data(&dn, page->index, LOOKUP_NODE);
        if (err)
                return err;

        fio->blk_addr = dn.data_blkaddr;

        /* This page is already truncated */
        if (fio->blk_addr == NULL_ADDR) {
                ClearPageUptodate(page);
                goto out_writepage;
        }

        set_page_writeback(page);

        /*
         * If current allocation needs SSR,
         * it had better in-place writes for updated data.
         */
        if (unlikely(fio->blk_addr != NEW_ADDR &&
                        !is_cold_data(page) &&
                        need_inplace_update(inode))) {
                rewrite_data_page(page, fio);
                set_inode_flag(F2FS_I(inode), FI_UPDATE_WRITE);
                trace_f2fs_do_write_data_page(page, IPU);
        } else {
                write_data_page(page, &dn, fio);
                set_data_blkaddr(&dn);
                f2fs_update_extent_cache(&dn);
                trace_f2fs_do_write_data_page(page, OPU);
                set_inode_flag(F2FS_I(inode), FI_APPEND_WRITE);
                if (page->index == 0)
                        set_inode_flag(F2FS_I(inode), FI_FIRST_BLOCK_WRITTEN);
        }
out_writepage:
        f2fs_put_dnode(&dn);
        return err;
}

static int f2fs_write_data_page(struct page *page,
                                        struct writeback_control *wbc)
{
        struct inode *inode = page->mapping->host;
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        loff_t i_size = i_size_read(inode);
        const pgoff_t end_index = ((unsigned long long) i_size)
                                                        >> PAGE_CACHE_SHIFT;
        unsigned offset = 0;
        bool need_balance_fs = false;
        int err = 0;
        struct f2fs_io_info fio = {
                .type = DATA,
                .rw = (wbc->sync_mode == WB_SYNC_ALL) ? WRITE_SYNC : WRITE,
        };

        trace_f2fs_writepage(page, DATA);

        if (page->index < end_index)
                goto write;

        /*
         * If the offset is out-of-range of file size,
         * this page does not have to be written to disk.
         */
        offset = i_size & (PAGE_CACHE_SIZE - 1);
        if ((page->index >= end_index + 1) || !offset)
                goto out;

        zero_user_segment(page, offset, PAGE_CACHE_SIZE);
write:
        if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
                goto redirty_out;
        if (f2fs_is_drop_cache(inode))
                goto out;
        if (f2fs_is_volatile_file(inode) && !wbc->for_reclaim &&
                        available_free_memory(sbi, BASE_CHECK))
                goto redirty_out;

        /* Dentry blocks are controlled by checkpoint */
        if (S_ISDIR(inode->i_mode)) {
                if (unlikely(f2fs_cp_error(sbi)))
                        goto redirty_out;
                err = do_write_data_page(page, &fio);
                goto done;
        }

        /* we should bypass data pages to proceed the kworkder jobs */
        if (unlikely(f2fs_cp_error(sbi))) {
                SetPageError(page);
                goto out;
        }

        if (!wbc->for_reclaim)
                need_balance_fs = true;
        else if (has_not_enough_free_secs(sbi, 0))
                goto redirty_out;

        err = -EAGAIN;
        f2fs_lock_op(sbi);
        if (f2fs_has_inline_data(inode))
                err = f2fs_write_inline_data(inode, page);
        if (err == -EAGAIN)
                err = do_write_data_page(page, &fio);
        f2fs_unlock_op(sbi);
done:
        if (err && err != -ENOENT)
                goto redirty_out;

        clear_cold_data(page);
out:
        inode_dec_dirty_pages(inode);
        if (err)
                ClearPageUptodate(page);
        unlock_page(page);
        if (need_balance_fs)
                f2fs_balance_fs(sbi);
        if (wbc->for_reclaim)
                f2fs_submit_merged_bio(sbi, DATA, WRITE);
        return 0;

redirty_out:
        redirty_page_for_writepage(wbc, page);
        return AOP_WRITEPAGE_ACTIVATE;
}

static int __f2fs_writepage(struct page *page, struct writeback_control *wbc,
                        void *data)
{
        struct address_space *mapping = data;
        int ret = mapping->a_ops->writepage(page, wbc);
        mapping_set_error(mapping, ret);
        return ret;
}

static int f2fs_write_data_pages(struct address_space *mapping,
                            struct writeback_control *wbc)
{
        struct inode *inode = mapping->host;
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        int ret;
        long diff;

        trace_f2fs_writepages(mapping->host, wbc, DATA);

        /* deal with chardevs and other special file */
        if (!mapping->a_ops->writepage)
                return 0;

        if (S_ISDIR(inode->i_mode) && wbc->sync_mode == WB_SYNC_NONE &&
                        get_dirty_pages(inode) < nr_pages_to_skip(sbi, DATA) &&
                        available_free_memory(sbi, DIRTY_DENTS))
                goto skip_write;

        /* during POR, we don't need to trigger writepage at all. */
        if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
                goto skip_write;

        diff = nr_pages_to_write(sbi, DATA, wbc);

        ret = write_cache_pages(mapping, wbc, __f2fs_writepage, mapping);

        f2fs_submit_merged_bio(sbi, DATA, WRITE);

        remove_dirty_dir_inode(inode);

        wbc->nr_to_write = max((long)0, wbc->nr_to_write - diff);
        return ret;

skip_write:
        wbc->pages_skipped += get_dirty_pages(inode);
        return 0;
}

static void f2fs_write_failed(struct address_space *mapping, loff_t to)
{
        struct inode *inode = mapping->host;

        if (to > inode->i_size) {
                truncate_pagecache(inode, inode->i_size);
                truncate_blocks(inode, inode->i_size, true);
        }
}

static int f2fs_write_begin(struct file *file, struct address_space *mapping,
                loff_t pos, unsigned len, unsigned flags,
                struct page **pagep, void **fsdata)
{
        struct inode *inode = mapping->host;
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct page *page, *ipage;
        pgoff_t index = ((unsigned long long) pos) >> PAGE_CACHE_SHIFT;
        struct dnode_of_data dn;
        int err = 0;

        trace_f2fs_write_begin(inode, pos, len, flags);

        f2fs_balance_fs(sbi);

        /*
         * We should check this at this moment to avoid deadlock on inode page
         * and #0 page. The locking rule for inline_data conversion should be:
         * lock_page(page #0) -> lock_page(inode_page)
         */
        if (index != 0) {
                err = f2fs_convert_inline_inode(inode);
                if (err)
                        goto fail;
        }
repeat:
        page = grab_cache_page_write_begin(mapping, index, flags);
        if (!page) {
                err = -ENOMEM;
                goto fail;
        }

        *pagep = page;

        f2fs_lock_op(sbi);

        /* check inline_data */
        ipage = get_node_page(sbi, inode->i_ino);
        if (IS_ERR(ipage)) {
                err = PTR_ERR(ipage);
                goto unlock_fail;
        }

        set_new_dnode(&dn, inode, ipage, ipage, 0);

        if (f2fs_has_inline_data(inode)) {
                if (pos + len <= MAX_INLINE_DATA) {
                        read_inline_data(page, ipage);
                        set_inode_flag(F2FS_I(inode), FI_DATA_EXIST);
                        sync_inode_page(&dn);
                        goto put_next;
                }
                err = f2fs_convert_inline_page(&dn, page);
                if (err)
                        goto put_fail;
        }
        err = f2fs_reserve_block(&dn, index);
        if (err)
                goto put_fail;
put_next:
        f2fs_put_dnode(&dn);
        f2fs_unlock_op(sbi);

        if ((len == PAGE_CACHE_SIZE) || PageUptodate(page))
                return 0;

        f2fs_wait_on_page_writeback(page, DATA);

        if ((pos & PAGE_CACHE_MASK) >= i_size_read(inode)) {
                unsigned start = pos & (PAGE_CACHE_SIZE - 1);
                unsigned end = start + len;

                /* Reading beyond i_size is simple: memset to zero */
                zero_user_segments(page, 0, start, end, PAGE_CACHE_SIZE);
                goto out;
        }

        if (dn.data_blkaddr == NEW_ADDR) {
                zero_user_segment(page, 0, PAGE_CACHE_SIZE);
        } else {
                struct f2fs_io_info fio = {
                        .type = DATA,
                        .rw = READ_SYNC,
                        .blk_addr = dn.data_blkaddr,
                };
                err = f2fs_submit_page_bio(sbi, page, &fio);
                if (err)
                        goto fail;

                lock_page(page);
                if (unlikely(!PageUptodate(page))) {
                        f2fs_put_page(page, 1);
                        err = -EIO;
                        goto fail;
                }
                if (unlikely(page->mapping != mapping)) {
                        f2fs_put_page(page, 1);
                        goto repeat;
                }
        }
out:
        SetPageUptodate(page);
        clear_cold_data(page);
        return 0;

put_fail:
        f2fs_put_dnode(&dn);
unlock_fail:
        f2fs_unlock_op(sbi);
        f2fs_put_page(page, 1);
fail:
        f2fs_write_failed(mapping, pos + len);
        return err;
}

static int f2fs_write_end(struct file *file,
                        struct address_space *mapping,
                        loff_t pos, unsigned len, unsigned copied,
                        struct page *page, void *fsdata)
{
        struct inode *inode = page->mapping->host;

        trace_f2fs_write_end(inode, pos, len, copied);

        set_page_dirty(page);

        if (pos + copied > i_size_read(inode)) {
                i_size_write(inode, pos + copied);
                mark_inode_dirty(inode);
                update_inode_page(inode);
        }

        f2fs_put_page(page, 1);
        return copied;
}

static int check_direct_IO(struct inode *inode, int rw,
                struct iov_iter *iter, loff_t offset)
{
        unsigned blocksize_mask = inode->i_sb->s_blocksize - 1;

        if (rw == READ)
                return 0;

        if (offset & blocksize_mask)
                return -EINVAL;

        if (iov_iter_alignment(iter) & blocksize_mask)
                return -EINVAL;

        return 0;
}

static ssize_t f2fs_direct_IO(int rw, struct kiocb *iocb,
                struct iov_iter *iter, loff_t offset)
{
        struct file *file = iocb->ki_filp;
        struct address_space *mapping = file->f_mapping;
        struct inode *inode = mapping->host;
        size_t count = iov_iter_count(iter);
        int err;

        /* we don't need to use inline_data strictly */
        if (f2fs_has_inline_data(inode)) {
                err = f2fs_convert_inline_inode(inode);
                if (err)
                        return err;
        }

        if (check_direct_IO(inode, rw, iter, offset))
                return 0;

        trace_f2fs_direct_IO_enter(inode, offset, count, rw);

        if (rw & WRITE)
                __allocate_data_blocks(inode, offset, count);

        err = blockdev_direct_IO(rw, iocb, inode, iter, offset, get_data_block);
        if (err < 0 && (rw & WRITE))
                f2fs_write_failed(mapping, offset + count);

        trace_f2fs_direct_IO_exit(inode, offset, count, rw, err);

        return err;
}

void f2fs_invalidate_page(struct page *page, unsigned int offset,
                                                        unsigned int length)
{
        struct inode *inode = page->mapping->host;
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);

        if (inode->i_ino >= F2FS_ROOT_INO(sbi) &&
                (offset % PAGE_CACHE_SIZE || length != PAGE_CACHE_SIZE))
                return;

        if (PageDirty(page)) {
                if (inode->i_ino == F2FS_META_INO(sbi))
                        dec_page_count(sbi, F2FS_DIRTY_META);
                else if (inode->i_ino == F2FS_NODE_INO(sbi))
                        dec_page_count(sbi, F2FS_DIRTY_NODES);
                else
                        inode_dec_dirty_pages(inode);
        }
        ClearPagePrivate(page);
}

int f2fs_release_page(struct page *page, gfp_t wait)
{
        /* If this is dirty page, keep PagePrivate */
        if (PageDirty(page))
                return 0;

        ClearPagePrivate(page);
        return 1;
}

static int f2fs_set_data_page_dirty(struct page *page)
{
        struct address_space *mapping = page->mapping;
        struct inode *inode = mapping->host;

        trace_f2fs_set_page_dirty(page, DATA);

        SetPageUptodate(page);

        if (f2fs_is_atomic_file(inode)) {
                register_inmem_page(inode, page);
                return 1;
        }

        mark_inode_dirty(inode);

        if (!PageDirty(page)) {
                __set_page_dirty_nobuffers(page);
                update_dirty_page(inode, page);
                return 1;
        }
        return 0;
}

static sector_t f2fs_bmap(struct address_space *mapping, sector_t block)
{
        struct inode *inode = mapping->host;

        /* we don't need to use inline_data strictly */
        if (f2fs_has_inline_data(inode)) {
                int err = f2fs_convert_inline_inode(inode);
                if (err)
                        return err;
        }
        return generic_block_bmap(mapping, block, get_data_block);
}

void init_extent_cache_info(struct f2fs_sb_info *sbi)
{
        INIT_RADIX_TREE(&sbi->extent_tree_root, GFP_NOIO);
        init_rwsem(&sbi->extent_tree_lock);
        INIT_LIST_HEAD(&sbi->extent_list);
        spin_lock_init(&sbi->extent_lock);
        sbi->total_ext_tree = 0;
        atomic_set(&sbi->total_ext_node, 0);
}

int __init create_extent_cache(void)
{
        extent_tree_slab = f2fs_kmem_cache_create("f2fs_extent_tree",
                        sizeof(struct extent_tree));
        if (!extent_tree_slab)
                return -ENOMEM;
        extent_node_slab = f2fs_kmem_cache_create("f2fs_extent_node",
                        sizeof(struct extent_node));
        if (!extent_node_slab) {
                kmem_cache_destroy(extent_tree_slab);
                return -ENOMEM;
        }
        return 0;
}

void destroy_extent_cache(void)
{
        kmem_cache_destroy(extent_node_slab);
        kmem_cache_destroy(extent_tree_slab);
}

const struct address_space_operations f2fs_dblock_aops = {
        .readpage       = f2fs_read_data_page,
        .readpages      = f2fs_read_data_pages,
        .writepage      = f2fs_write_data_page,
        .writepages     = f2fs_write_data_pages,
        .write_begin    = f2fs_write_begin,
        .write_end      = f2fs_write_end,
        .set_page_dirty = f2fs_set_data_page_dirty,
        .invalidatepage = f2fs_invalidate_page,
        .releasepage    = f2fs_release_page,
        .direct_IO      = f2fs_direct_IO,
        .bmap           = f2fs_bmap,
};