// SPDX-License-Identifier: GPL-2.0
/*
 * fs/f2fs/data.c
 *
 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
 *             http://www.samsung.com/
 */
#include <linux/fs.h>
#include <linux/f2fs_fs.h>
#include <linux/buffer_head.h>
#include <linux/mpage.h>
#include <linux/writeback.h>
#include <linux/backing-dev.h>
#include <linux/pagevec.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/swap.h>
#include <linux/prefetch.h>
#include <linux/uio.h>
#include <linux/cleancache.h>
#include <linux/sched/signal.h>

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

#define NUM_PREALLOC_POST_READ_CTXS     128

static struct kmem_cache *bio_post_read_ctx_cache;
static mempool_t *bio_post_read_ctx_pool;

static bool __is_cp_guaranteed(struct page *page)
{
        struct address_space *mapping = page->mapping;
        struct inode *inode;
        struct f2fs_sb_info *sbi;

        if (!mapping)
                return false;

        inode = mapping->host;
        sbi = F2FS_I_SB(inode);

        if (inode->i_ino == F2FS_META_INO(sbi) ||
                        inode->i_ino ==  F2FS_NODE_INO(sbi) ||
                        S_ISDIR(inode->i_mode) ||
                        (S_ISREG(inode->i_mode) &&
                        (f2fs_is_atomic_file(inode) || IS_NOQUOTA(inode))) ||
                        is_cold_data(page))
                return true;
        return false;
}

static enum count_type __read_io_type(struct page *page)
{
        struct address_space *mapping = page_file_mapping(page);

        if (mapping) {
                struct inode *inode = mapping->host;
                struct f2fs_sb_info *sbi = F2FS_I_SB(inode);

                if (inode->i_ino == F2FS_META_INO(sbi))
                        return F2FS_RD_META;

                if (inode->i_ino == F2FS_NODE_INO(sbi))
                        return F2FS_RD_NODE;
        }
        return F2FS_RD_DATA;
}

/* postprocessing steps for read bios */
enum bio_post_read_step {
        STEP_INITIAL = 0,
        STEP_DECRYPT,
        STEP_VERITY,
};

struct bio_post_read_ctx {
        struct bio *bio;
        struct work_struct work;
        unsigned int cur_step;
        unsigned int enabled_steps;
};

static void __read_end_io(struct bio *bio)
{
        struct page *page;
        struct bio_vec *bv;
        struct bvec_iter_all iter_all;

        bio_for_each_segment_all(bv, bio, iter_all) {
                page = bv->bv_page;

                /* PG_error was set if any post_read step failed */
                if (bio->bi_status || PageError(page)) {
                        ClearPageUptodate(page);
                        /* will re-read again later */
                        ClearPageError(page);
                } else {
                        SetPageUptodate(page);
                }
                dec_page_count(F2FS_P_SB(page), __read_io_type(page));
                unlock_page(page);
        }
        if (bio->bi_private)
                mempool_free(bio->bi_private, bio_post_read_ctx_pool);
        bio_put(bio);
}

static void bio_post_read_processing(struct bio_post_read_ctx *ctx);

static void decrypt_work(struct work_struct *work)
{
        struct bio_post_read_ctx *ctx =
                container_of(work, struct bio_post_read_ctx, work);

        fscrypt_decrypt_bio(ctx->bio);

        bio_post_read_processing(ctx);
}

static void verity_work(struct work_struct *work)
{
        struct bio_post_read_ctx *ctx =
                container_of(work, struct bio_post_read_ctx, work);

        fsverity_verify_bio(ctx->bio);

        bio_post_read_processing(ctx);
}

static void bio_post_read_processing(struct bio_post_read_ctx *ctx)
{
        /*
         * We use different work queues for decryption and for verity because
         * verity may require reading metadata pages that need decryption, and
         * we shouldn't recurse to the same workqueue.
         */
        switch (++ctx->cur_step) {
        case STEP_DECRYPT:
                if (ctx->enabled_steps & (1 << STEP_DECRYPT)) {
                        INIT_WORK(&ctx->work, decrypt_work);
                        fscrypt_enqueue_decrypt_work(&ctx->work);
                        return;
                }
                ctx->cur_step++;
                /* fall-through */
        case STEP_VERITY:
                if (ctx->enabled_steps & (1 << STEP_VERITY)) {
                        INIT_WORK(&ctx->work, verity_work);
                        fsverity_enqueue_verify_work(&ctx->work);
                        return;
                }
                ctx->cur_step++;
                /* fall-through */
        default:
                __read_end_io(ctx->bio);
        }
}

static bool f2fs_bio_post_read_required(struct bio *bio)
{
        return bio->bi_private && !bio->bi_status;
}

static void f2fs_read_end_io(struct bio *bio)
{
        if (time_to_inject(F2FS_P_SB(bio_first_page_all(bio)),
                                                FAULT_READ_IO)) {
                f2fs_show_injection_info(FAULT_READ_IO);
                bio->bi_status = BLK_STS_IOERR;
        }

        if (f2fs_bio_post_read_required(bio)) {
                struct bio_post_read_ctx *ctx = bio->bi_private;

                ctx->cur_step = STEP_INITIAL;
                bio_post_read_processing(ctx);
                return;
        }

        __read_end_io(bio);
}

static void f2fs_write_end_io(struct bio *bio)
{
        struct f2fs_sb_info *sbi = bio->bi_private;
        struct bio_vec *bvec;
        struct bvec_iter_all iter_all;

        if (time_to_inject(sbi, FAULT_WRITE_IO)) {
                f2fs_show_injection_info(FAULT_WRITE_IO);
                bio->bi_status = BLK_STS_IOERR;
        }

        bio_for_each_segment_all(bvec, bio, iter_all) {
                struct page *page = bvec->bv_page;
                enum count_type type = WB_DATA_TYPE(page);

                if (IS_DUMMY_WRITTEN_PAGE(page)) {
                        set_page_private(page, (unsigned long)NULL);
                        ClearPagePrivate(page);
                        unlock_page(page);
                        mempool_free(page, sbi->write_io_dummy);

                        if (unlikely(bio->bi_status))
                                f2fs_stop_checkpoint(sbi, true);
                        continue;
                }

                fscrypt_finalize_bounce_page(&page);

                if (unlikely(bio->bi_status)) {
                        mapping_set_error(page->mapping, -EIO);
                        if (type == F2FS_WB_CP_DATA)
                                f2fs_stop_checkpoint(sbi, true);
                }

                f2fs_bug_on(sbi, page->mapping == NODE_MAPPING(sbi) &&
                                        page->index != nid_of_node(page));

                dec_page_count(sbi, type);
                if (f2fs_in_warm_node_list(sbi, page))
                        f2fs_del_fsync_node_entry(sbi, page);
                clear_cold_data(page);
                end_page_writeback(page);
        }
        if (!get_pages(sbi, F2FS_WB_CP_DATA) &&
                                wq_has_sleeper(&sbi->cp_wait))
                wake_up(&sbi->cp_wait);

        bio_put(bio);
}

/*
 * Return true, if pre_bio's bdev is same as its target device.
 */
struct block_device *f2fs_target_device(struct f2fs_sb_info *sbi,
                                block_t blk_addr, struct bio *bio)
{
        struct block_device *bdev = sbi->sb->s_bdev;
        int i;

        if (f2fs_is_multi_device(sbi)) {
                for (i = 0; i < sbi->s_ndevs; i++) {
                        if (FDEV(i).start_blk <= blk_addr &&
                            FDEV(i).end_blk >= blk_addr) {
                                blk_addr -= FDEV(i).start_blk;
                                bdev = FDEV(i).bdev;
                                break;
                        }
                }
        }
        if (bio) {
                bio_set_dev(bio, bdev);
                bio->bi_iter.bi_sector = SECTOR_FROM_BLOCK(blk_addr);
        }
        return bdev;
}

int f2fs_target_device_index(struct f2fs_sb_info *sbi, block_t blkaddr)
{
        int i;

        if (!f2fs_is_multi_device(sbi))
                return 0;

        for (i = 0; i < sbi->s_ndevs; i++)
                if (FDEV(i).start_blk <= blkaddr && FDEV(i).end_blk >= blkaddr)
                        return i;
        return 0;
}

static bool __same_bdev(struct f2fs_sb_info *sbi,
                                block_t blk_addr, struct bio *bio)
{
        struct block_device *b = f2fs_target_device(sbi, blk_addr, NULL);
        return bio->bi_disk == b->bd_disk && bio->bi_partno == b->bd_partno;
}

/*
 * Low-level block read/write IO operations.
 */
static struct bio *__bio_alloc(struct f2fs_io_info *fio, int npages)
{
        struct f2fs_sb_info *sbi = fio->sbi;
        struct bio *bio;

        bio = f2fs_bio_alloc(sbi, npages, true);

        f2fs_target_device(sbi, fio->new_blkaddr, bio);
        if (is_read_io(fio->op)) {
                bio->bi_end_io = f2fs_read_end_io;
                bio->bi_private = NULL;
        } else {
                bio->bi_end_io = f2fs_write_end_io;
                bio->bi_private = sbi;
                bio->bi_write_hint = f2fs_io_type_to_rw_hint(sbi,
                                                fio->type, fio->temp);
        }
        if (fio->io_wbc)
                wbc_init_bio(fio->io_wbc, bio);

        return bio;
}

static inline void __submit_bio(struct f2fs_sb_info *sbi,
                                struct bio *bio, enum page_type type)
{
        if (!is_read_io(bio_op(bio))) {
                unsigned int start;

                if (type != DATA && type != NODE)
                        goto submit_io;

                if (test_opt(sbi, LFS) && current->plug)
                        blk_finish_plug(current->plug);

                if (F2FS_IO_ALIGNED(sbi))
                        goto submit_io;

                start = bio->bi_iter.bi_size >> F2FS_BLKSIZE_BITS;
                start %= F2FS_IO_SIZE(sbi);

                if (start == 0)
                        goto submit_io;

                /* fill dummy pages */
                for (; start < F2FS_IO_SIZE(sbi); start++) {
                        struct page *page =
                                mempool_alloc(sbi->write_io_dummy,
                                              GFP_NOIO | __GFP_NOFAIL);
                        f2fs_bug_on(sbi, !page);

                        zero_user_segment(page, 0, PAGE_SIZE);
                        SetPagePrivate(page);
                        set_page_private(page, (unsigned long)DUMMY_WRITTEN_PAGE);
                        lock_page(page);
                        if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE)
                                f2fs_bug_on(sbi, 1);
                }
                /*
                 * In the NODE case, we lose next block address chain. So, we
                 * need to do checkpoint in f2fs_sync_file.
                 */
                if (type == NODE)
                        set_sbi_flag(sbi, SBI_NEED_CP);
        }
submit_io:
        if (is_read_io(bio_op(bio)))
                trace_f2fs_submit_read_bio(sbi->sb, type, bio);
        else
                trace_f2fs_submit_write_bio(sbi->sb, type, bio);
        submit_bio(bio);
}

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

        if (!io->bio)
                return;

        bio_set_op_attrs(io->bio, fio->op, fio->op_flags);

        if (is_read_io(fio->op))
                trace_f2fs_prepare_read_bio(io->sbi->sb, fio->type, io->bio);
        else
                trace_f2fs_prepare_write_bio(io->sbi->sb, fio->type, io->bio);

        __submit_bio(io->sbi, io->bio, fio->type);
        io->bio = NULL;
}

static bool __has_merged_page(struct bio *bio, struct inode *inode,
                                                struct page *page, nid_t ino)
{
        struct bio_vec *bvec;
        struct page *target;
        struct bvec_iter_all iter_all;

        if (!bio)
                return false;

        if (!inode && !page && !ino)
                return true;

        bio_for_each_segment_all(bvec, bio, iter_all) {

                target = bvec->bv_page;
                if (fscrypt_is_bounce_page(target))
                        target = fscrypt_pagecache_page(target);

                if (inode && inode == target->mapping->host)
                        return true;
                if (page && page == target)
                        return true;
                if (ino && ino == ino_of_node(target))
                        return true;
        }

        return false;
}

static void __f2fs_submit_merged_write(struct f2fs_sb_info *sbi,
                                enum page_type type, enum temp_type temp)
{
        enum page_type btype = PAGE_TYPE_OF_BIO(type);
        struct f2fs_bio_info *io = sbi->write_io[btype] + temp;

        down_write(&io->io_rwsem);

        /* change META to META_FLUSH in the checkpoint procedure */
        if (type >= META_FLUSH) {
                io->fio.type = META_FLUSH;
                io->fio.op = REQ_OP_WRITE;
                io->fio.op_flags = REQ_META | REQ_PRIO | REQ_SYNC;
                if (!test_opt(sbi, NOBARRIER))
                        io->fio.op_flags |= REQ_PREFLUSH | REQ_FUA;
        }
        __submit_merged_bio(io);
        up_write(&io->io_rwsem);
}

static void __submit_merged_write_cond(struct f2fs_sb_info *sbi,
                                struct inode *inode, struct page *page,
                                nid_t ino, enum page_type type, bool force)
{
        enum temp_type temp;
        bool ret = true;

        for (temp = HOT; temp < NR_TEMP_TYPE; temp++) {
                if (!force)     {
                        enum page_type btype = PAGE_TYPE_OF_BIO(type);
                        struct f2fs_bio_info *io = sbi->write_io[btype] + temp;

                        down_read(&io->io_rwsem);
                        ret = __has_merged_page(io->bio, inode, page, ino);
                        up_read(&io->io_rwsem);
                }
                if (ret)
                        __f2fs_submit_merged_write(sbi, type, temp);

                /* TODO: use HOT temp only for meta pages now. */
                if (type >= META)
                        break;
        }
}

void f2fs_submit_merged_write(struct f2fs_sb_info *sbi, enum page_type type)
{
        __submit_merged_write_cond(sbi, NULL, NULL, 0, type, true);
}

void f2fs_submit_merged_write_cond(struct f2fs_sb_info *sbi,
                                struct inode *inode, struct page *page,
                                nid_t ino, enum page_type type)
{
        __submit_merged_write_cond(sbi, inode, page, ino, type, false);
}

void f2fs_flush_merged_writes(struct f2fs_sb_info *sbi)
{
        f2fs_submit_merged_write(sbi, DATA);
        f2fs_submit_merged_write(sbi, NODE);
        f2fs_submit_merged_write(sbi, META);
}

/*
 * Fill the locked page with data located in the block address.
 * A caller needs to unlock the page on failure.
 */
int f2fs_submit_page_bio(struct f2fs_io_info *fio)
{
        struct bio *bio;
        struct page *page = fio->encrypted_page ?
                        fio->encrypted_page : fio->page;

        if (!f2fs_is_valid_blkaddr(fio->sbi, fio->new_blkaddr,
                        fio->is_por ? META_POR : (__is_meta_io(fio) ?
                        META_GENERIC : DATA_GENERIC_ENHANCE)))
                return -EFSCORRUPTED;

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

        /* Allocate a new bio */
        bio = __bio_alloc(fio, 1);

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

        if (fio->io_wbc && !is_read_io(fio->op))
                wbc_account_cgroup_owner(fio->io_wbc, page, PAGE_SIZE);

        bio_set_op_attrs(bio, fio->op, fio->op_flags);

        inc_page_count(fio->sbi, is_read_io(fio->op) ?
                        __read_io_type(page): WB_DATA_TYPE(fio->page));

        __submit_bio(fio->sbi, bio, fio->type);
        return 0;
}

static bool page_is_mergeable(struct f2fs_sb_info *sbi, struct bio *bio,
                                block_t last_blkaddr, block_t cur_blkaddr)
{
        if (last_blkaddr + 1 != cur_blkaddr)
                return false;
        return __same_bdev(sbi, cur_blkaddr, bio);
}

static bool io_type_is_mergeable(struct f2fs_bio_info *io,
                                                struct f2fs_io_info *fio)
{
        if (io->fio.op != fio->op)
                return false;
        return io->fio.op_flags == fio->op_flags;
}

static bool io_is_mergeable(struct f2fs_sb_info *sbi, struct bio *bio,
                                        struct f2fs_bio_info *io,
                                        struct f2fs_io_info *fio,
                                        block_t last_blkaddr,
                                        block_t cur_blkaddr)
{
        if (F2FS_IO_ALIGNED(sbi) && (fio->type == DATA || fio->type == NODE)) {
                unsigned int filled_blocks =
                                F2FS_BYTES_TO_BLK(bio->bi_iter.bi_size);
                unsigned int io_size = F2FS_IO_SIZE(sbi);
                unsigned int left_vecs = bio->bi_max_vecs - bio->bi_vcnt;

                /* IOs in bio is aligned and left space of vectors is not enough */
                if (!(filled_blocks % io_size) && left_vecs < io_size)
                        return false;
        }
        if (!page_is_mergeable(sbi, bio, last_blkaddr, cur_blkaddr))
                return false;
        return io_type_is_mergeable(io, fio);
}

int f2fs_merge_page_bio(struct f2fs_io_info *fio)
{
        struct bio *bio = *fio->bio;
        struct page *page = fio->encrypted_page ?
                        fio->encrypted_page : fio->page;

        if (!f2fs_is_valid_blkaddr(fio->sbi, fio->new_blkaddr,
                        __is_meta_io(fio) ? META_GENERIC : DATA_GENERIC))
                return -EFSCORRUPTED;

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

        if (bio && !page_is_mergeable(fio->sbi, bio, *fio->last_block,
                                                fio->new_blkaddr)) {
                __submit_bio(fio->sbi, bio, fio->type);
                bio = NULL;
        }
alloc_new:
        if (!bio) {
                bio = __bio_alloc(fio, BIO_MAX_PAGES);
                bio_set_op_attrs(bio, fio->op, fio->op_flags);
        }

        if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
                __submit_bio(fio->sbi, bio, fio->type);
                bio = NULL;
                goto alloc_new;
        }

        if (fio->io_wbc)
                wbc_account_cgroup_owner(fio->io_wbc, page, PAGE_SIZE);

        inc_page_count(fio->sbi, WB_DATA_TYPE(page));

        *fio->last_block = fio->new_blkaddr;
        *fio->bio = bio;

        return 0;
}

static void f2fs_submit_ipu_bio(struct f2fs_sb_info *sbi, struct bio **bio,
                                                        struct page *page)
{
        if (!bio)
                return;

        if (!__has_merged_page(*bio, NULL, page, 0))
                return;

        __submit_bio(sbi, *bio, DATA);
        *bio = NULL;
}

void f2fs_submit_page_write(struct f2fs_io_info *fio)
{
        struct f2fs_sb_info *sbi = fio->sbi;
        enum page_type btype = PAGE_TYPE_OF_BIO(fio->type);
        struct f2fs_bio_info *io = sbi->write_io[btype] + fio->temp;
        struct page *bio_page;

        f2fs_bug_on(sbi, is_read_io(fio->op));

        down_write(&io->io_rwsem);
next:
        if (fio->in_list) {
                spin_lock(&io->io_lock);
                if (list_empty(&io->io_list)) {
                        spin_unlock(&io->io_lock);
                        goto out;
                }
                fio = list_first_entry(&io->io_list,
                                                struct f2fs_io_info, list);
                list_del(&fio->list);
                spin_unlock(&io->io_lock);
        }

        verify_fio_blkaddr(fio);

        bio_page = fio->encrypted_page ? fio->encrypted_page : fio->page;

        /* set submitted = true as a return value */
        fio->submitted = true;

        inc_page_count(sbi, WB_DATA_TYPE(bio_page));

        if (io->bio && !io_is_mergeable(sbi, io->bio, io, fio,
                        io->last_block_in_bio, fio->new_blkaddr))
                __submit_merged_bio(io);
alloc_new:
        if (io->bio == NULL) {
                if (F2FS_IO_ALIGNED(sbi) &&
                                (fio->type == DATA || fio->type == NODE) &&
                                fio->new_blkaddr & F2FS_IO_SIZE_MASK(sbi)) {
                        dec_page_count(sbi, WB_DATA_TYPE(bio_page));
                        fio->retry = true;
                        goto skip;
                }
                io->bio = __bio_alloc(fio, BIO_MAX_PAGES);
                io->fio = *fio;
        }

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

        if (fio->io_wbc)
                wbc_account_cgroup_owner(fio->io_wbc, bio_page, PAGE_SIZE);

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

        trace_f2fs_submit_page_write(fio->page, fio);
skip:
        if (fio->in_list)
                goto next;
out:
        if (is_sbi_flag_set(sbi, SBI_IS_SHUTDOWN) ||
                                !f2fs_is_checkpoint_ready(sbi))
                __submit_merged_bio(io);
        up_write(&io->io_rwsem);
}

static inline bool f2fs_need_verity(const struct inode *inode, pgoff_t idx)
{
        return fsverity_active(inode) &&
               idx < DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
}

static struct bio *f2fs_grab_read_bio(struct inode *inode, block_t blkaddr,
                                      unsigned nr_pages, unsigned op_flag,
                                      pgoff_t first_idx)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct bio *bio;
        struct bio_post_read_ctx *ctx;
        unsigned int post_read_steps = 0;

        bio = f2fs_bio_alloc(sbi, min_t(int, nr_pages, BIO_MAX_PAGES), false);
        if (!bio)
                return ERR_PTR(-ENOMEM);
        f2fs_target_device(sbi, blkaddr, bio);
        bio->bi_end_io = f2fs_read_end_io;
        bio_set_op_attrs(bio, REQ_OP_READ, op_flag);

        if (f2fs_encrypted_file(inode))
                post_read_steps |= 1 << STEP_DECRYPT;

        if (f2fs_need_verity(inode, first_idx))
                post_read_steps |= 1 << STEP_VERITY;

        if (post_read_steps) {
                ctx = mempool_alloc(bio_post_read_ctx_pool, GFP_NOFS);
                if (!ctx) {
                        bio_put(bio);
                        return ERR_PTR(-ENOMEM);
                }
                ctx->bio = bio;
                ctx->enabled_steps = post_read_steps;
                bio->bi_private = ctx;
        }

        return bio;
}

/* This can handle encryption stuffs */
static int f2fs_submit_page_read(struct inode *inode, struct page *page,
                                                        block_t blkaddr)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct bio *bio;

        bio = f2fs_grab_read_bio(inode, blkaddr, 1, 0, page->index);
        if (IS_ERR(bio))
                return PTR_ERR(bio);

        /* wait for GCed page writeback via META_MAPPING */
        f2fs_wait_on_block_writeback(inode, blkaddr);

        if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
                bio_put(bio);
                return -EFAULT;
        }
        ClearPageError(page);
        inc_page_count(sbi, F2FS_RD_DATA);
        __submit_bio(sbi, bio, DATA);
        return 0;
}

static void __set_data_blkaddr(struct dnode_of_data *dn)
{
        struct f2fs_node *rn = F2FS_NODE(dn->node_page);
        __le32 *addr_array;
        int base = 0;

        if (IS_INODE(dn->node_page) && f2fs_has_extra_attr(dn->inode))
                base = get_extra_isize(dn->inode);

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

/*
 * Lock ordering for the change of data block address:
 * ->data_page
 *  ->node_page
 *    update block addresses in the node page
 */
void f2fs_set_data_blkaddr(struct dnode_of_data *dn)
{
        f2fs_wait_on_page_writeback(dn->node_page, NODE, true, true);
        __set_data_blkaddr(dn);
        if (set_page_dirty(dn->node_page))
                dn->node_changed = true;
}

void f2fs_update_data_blkaddr(struct dnode_of_data *dn, block_t blkaddr)
{
        dn->data_blkaddr = blkaddr;
        f2fs_set_data_blkaddr(dn);
        f2fs_update_extent_cache(dn);
}

/* dn->ofs_in_node will be returned with up-to-date last block pointer */
int f2fs_reserve_new_blocks(struct dnode_of_data *dn, blkcnt_t count)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);
        int err;

        if (!count)
                return 0;

        if (unlikely(is_inode_flag_set(dn->inode, FI_NO_ALLOC)))
                return -EPERM;
        if (unlikely((err = inc_valid_block_count(sbi, dn->inode, &count))))
                return err;

        trace_f2fs_reserve_new_blocks(dn->inode, dn->nid,
                                                dn->ofs_in_node, count);

        f2fs_wait_on_page_writeback(dn->node_page, NODE, true, true);

        for (; count > 0; dn->ofs_in_node++) {
                block_t blkaddr = datablock_addr(dn->inode,
                                        dn->node_page, dn->ofs_in_node);
                if (blkaddr == NULL_ADDR) {
                        dn->data_blkaddr = NEW_ADDR;
                        __set_data_blkaddr(dn);
                        count--;
                }
        }

        if (set_page_dirty(dn->node_page))
                dn->node_changed = true;
        return 0;
}

/* Should keep dn->ofs_in_node unchanged */
int f2fs_reserve_new_block(struct dnode_of_data *dn)
{
        unsigned int ofs_in_node = dn->ofs_in_node;
        int ret;

        ret = f2fs_reserve_new_blocks(dn, 1);
        dn->ofs_in_node = ofs_in_node;
        return ret;
}

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

        err = f2fs_get_dnode_of_data(dn, index, ALLOC_NODE);
        if (err)
                return err;

        if (dn->data_blkaddr == NULL_ADDR)
                err = f2fs_reserve_new_block(dn);
        if (err || need_put)
                f2fs_put_dnode(dn);
        return err;
}

int f2fs_get_block(struct dnode_of_data *dn, pgoff_t index)
{
        struct extent_info ei  = {0,0,0};
        struct inode *inode = dn->inode;

        if (f2fs_lookup_extent_cache(inode, index, &ei)) {
                dn->data_blkaddr = ei.blk + index - ei.fofs;
                return 0;
        }

        return f2fs_reserve_block(dn, index);
}

struct page *f2fs_get_read_data_page(struct inode *inode, pgoff_t index,
                                                int op_flags, bool for_write)
{
        struct address_space *mapping = inode->i_mapping;
        struct dnode_of_data dn;
        struct page *page;
        struct extent_info ei = {0,0,0};
        int err;

        page = f2fs_grab_cache_page(mapping, index, for_write);
        if (!page)
                return ERR_PTR(-ENOMEM);

        if (f2fs_lookup_extent_cache(inode, index, &ei)) {
                dn.data_blkaddr = ei.blk + index - ei.fofs;
                if (!f2fs_is_valid_blkaddr(F2FS_I_SB(inode), dn.data_blkaddr,
                                                DATA_GENERIC_ENHANCE_READ)) {
                        err = -EFSCORRUPTED;
                        goto put_err;
                }
                goto got_it;
        }

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

        if (unlikely(dn.data_blkaddr == NULL_ADDR)) {
                err = -ENOENT;
                goto put_err;
        }
        if (dn.data_blkaddr != NEW_ADDR &&
                        !f2fs_is_valid_blkaddr(F2FS_I_SB(inode),
                                                dn.data_blkaddr,
                                                DATA_GENERIC_ENHANCE)) {
                err = -EFSCORRUPTED;
                goto put_err;
        }
got_it:
        if (PageUptodate(page)) {
                unlock_page(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 -> f2fs_get_new_data_page ->
         * f2fs_init_inode_metadata.
         */
        if (dn.data_blkaddr == NEW_ADDR) {
                zero_user_segment(page, 0, PAGE_SIZE);
                if (!PageUptodate(page))
                        SetPageUptodate(page);
                unlock_page(page);
                return page;
        }

        err = f2fs_submit_page_read(inode, page, dn.data_blkaddr);
        if (err)
                goto put_err;
        return page;

put_err:
        f2fs_put_page(page, 1);
        return ERR_PTR(err);
}

struct page *f2fs_find_data_page(struct inode *inode, pgoff_t index)
{
        struct address_space *mapping = inode->i_mapping;
        struct page *page;

        page = find_get_page(mapping, index);
        if (page && PageUptodate(page))
                return page;
        f2fs_put_page(page, 0);

        page = f2fs_get_read_data_page(inode, index, 0, false);
        if (IS_ERR(page))
                return page;

        if (PageUptodate(page))
                return page;

        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 *f2fs_get_lock_data_page(struct inode *inode, pgoff_t index,
                                                        bool for_write)
{
        struct address_space *mapping = inode->i_mapping;
        struct page *page;
repeat:
        page = f2fs_get_read_data_page(inode, index, 0, for_write);
        if (IS_ERR(page))
                return page;

        /* wait for read completion */
        lock_page(page);
        if (unlikely(page->mapping != mapping)) {
                f2fs_put_page(page, 1);
                goto repeat;
        }
        if (unlikely(!PageUptodate(page))) {
                f2fs_put_page(page, 1);
                return ERR_PTR(-EIO);
        }
        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, and if any error occur,
 * ipage should be released by this function.
 */
struct page *f2fs_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;

        page = f2fs_grab_cache_page(mapping, index, true);
        if (!page) {
                /*
                 * before exiting, we should make sure ipage will be released
                 * if any error occur.
                 */
                f2fs_put_page(ipage, 1);
                return ERR_PTR(-ENOMEM);
        }

        set_new_dnode(&dn, inode, ipage, NULL, 0);
        err = f2fs_reserve_block(&dn, index);
        if (err) {
                f2fs_put_page(page, 1);
                return ERR_PTR(err);

        }
        if (!ipage)
                f2fs_put_dnode(&dn);

        if (PageUptodate(page))
                goto got_it;

        if (dn.data_blkaddr == NEW_ADDR) {
                zero_user_segment(page, 0, PAGE_SIZE);
                if (!PageUptodate(page))
                        SetPageUptodate(page);
        } else {
                f2fs_put_page(page, 1);

                /* if ipage exists, blkaddr should be NEW_ADDR */
                f2fs_bug_on(F2FS_I_SB(inode), ipage);
                page = f2fs_get_lock_data_page(inode, index, true);
                if (IS_ERR(page))
                        return page;
        }
got_it:
        if (new_i_size && i_size_read(inode) <
                                ((loff_t)(index + 1) << PAGE_SHIFT))
                f2fs_i_size_write(inode, ((loff_t)(index + 1) << PAGE_SHIFT));
        return page;
}

static int __allocate_data_block(struct dnode_of_data *dn, int seg_type)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);
        struct f2fs_summary sum;
        struct node_info ni;
        block_t old_blkaddr;
        blkcnt_t count = 1;
        int err;

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

        err = f2fs_get_node_info(sbi, dn->nid, &ni);
        if (err)
                return err;

        dn->data_blkaddr = datablock_addr(dn->inode,
                                dn->node_page, dn->ofs_in_node);
        if (dn->data_blkaddr != NULL_ADDR)
                goto alloc;

        if (unlikely((err = inc_valid_block_count(sbi, dn->inode, &count))))
                return err;

alloc:
        set_summary(&sum, dn->nid, dn->ofs_in_node, ni.version);
        old_blkaddr = dn->data_blkaddr;
        f2fs_allocate_data_block(sbi, NULL, old_blkaddr, &dn->data_blkaddr,
                                        &sum, seg_type, NULL, false);
        if (GET_SEGNO(sbi, old_blkaddr) != NULL_SEGNO)
                invalidate_mapping_pages(META_MAPPING(sbi),
                                        old_blkaddr, old_blkaddr);
        f2fs_update_data_blkaddr(dn, dn->data_blkaddr);

        /*
         * i_size will be updated by direct_IO. Otherwise, we'll get stale
         * data from unwritten block via dio_read.
         */
        return 0;
}

int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *from)
{
        struct inode *inode = file_inode(iocb->ki_filp);
        struct f2fs_map_blocks map;
        int flag;
        int err = 0;
        bool direct_io = iocb->ki_flags & IOCB_DIRECT;

        /* convert inline data for Direct I/O*/
        if (direct_io) {
                err = f2fs_convert_inline_inode(inode);
                if (err)
                        return err;
        }

        if (direct_io && allow_outplace_dio(inode, iocb, from))
                return 0;

        if (is_inode_flag_set(inode, FI_NO_PREALLOC))
                return 0;

        map.m_lblk = F2FS_BLK_ALIGN(iocb->ki_pos);
        map.m_len = F2FS_BYTES_TO_BLK(iocb->ki_pos + iov_iter_count(from));
        if (map.m_len > map.m_lblk)
                map.m_len -= map.m_lblk;
        else
                map.m_len = 0;

        map.m_next_pgofs = NULL;
        map.m_next_extent = NULL;
        map.m_seg_type = NO_CHECK_TYPE;
        map.m_may_create = true;

        if (direct_io) {
                map.m_seg_type = f2fs_rw_hint_to_seg_type(iocb->ki_hint);
                flag = f2fs_force_buffered_io(inode, iocb, from) ?
                                        F2FS_GET_BLOCK_PRE_AIO :
                                        F2FS_GET_BLOCK_PRE_DIO;
                goto map_blocks;
        }
        if (iocb->ki_pos + iov_iter_count(from) > MAX_INLINE_DATA(inode)) {
                err = f2fs_convert_inline_inode(inode);
                if (err)
                        return err;
        }
        if (f2fs_has_inline_data(inode))
                return err;

        flag = F2FS_GET_BLOCK_PRE_AIO;

map_blocks:
        err = f2fs_map_blocks(inode, &map, 1, flag);
        if (map.m_len > 0 && err == -ENOSPC) {
                if (!direct_io)
                        set_inode_flag(inode, FI_NO_PREALLOC);
                err = 0;
        }
        return err;
}

void __do_map_lock(struct f2fs_sb_info *sbi, int flag, bool lock)
{
        if (flag == F2FS_GET_BLOCK_PRE_AIO) {
                if (lock)
                        down_read(&sbi->node_change);
                else
                        up_read(&sbi->node_change);
        } else {
                if (lock)
                        f2fs_lock_op(sbi);
                else
                        f2fs_unlock_op(sbi);
        }
}

/*
 * f2fs_map_blocks() now supported readahead/bmap/rw direct_IO with
 * f2fs_map_blocks structure.
 * 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
 */
int f2fs_map_blocks(struct inode *inode, struct f2fs_map_blocks *map,
                                                int create, int flag)
{
        unsigned int maxblocks = map->m_len;
        struct dnode_of_data dn;
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        int mode = map->m_may_create ? ALLOC_NODE : LOOKUP_NODE;
        pgoff_t pgofs, end_offset, end;
        int err = 0, ofs = 1;
        unsigned int ofs_in_node, last_ofs_in_node;
        blkcnt_t prealloc;
        struct extent_info ei = {0,0,0};
        block_t blkaddr;
        unsigned int start_pgofs;

        if (!maxblocks)
                return 0;

        map->m_len = 0;
        map->m_flags = 0;

        /* it only supports block size == page size */
        pgofs = (pgoff_t)map->m_lblk;
        end = pgofs + maxblocks;

        if (!create && f2fs_lookup_extent_cache(inode, pgofs, &ei)) {
                if (test_opt(sbi, LFS) && flag == F2FS_GET_BLOCK_DIO &&
                                                        map->m_may_create)
                        goto next_dnode;

                map->m_pblk = ei.blk + pgofs - ei.fofs;
                map->m_len = min((pgoff_t)maxblocks, ei.fofs + ei.len - pgofs);
                map->m_flags = F2FS_MAP_MAPPED;
                if (map->m_next_extent)
                        *map->m_next_extent = pgofs + map->m_len;

                /* for hardware encryption, but to avoid potential issue in future */
                if (flag == F2FS_GET_BLOCK_DIO)
                        f2fs_wait_on_block_writeback_range(inode,
                                                map->m_pblk, map->m_len);
                goto out;
        }

next_dnode:
        if (map->m_may_create)
                __do_map_lock(sbi, flag, true);

        /* When reading holes, we need its node page */
        set_new_dnode(&dn, inode, NULL, NULL, 0);
        err = f2fs_get_dnode_of_data(&dn, pgofs, mode);
        if (err) {
                if (flag == F2FS_GET_BLOCK_BMAP)
                        map->m_pblk = 0;
                if (err == -ENOENT) {
                        err = 0;
                        if (map->m_next_pgofs)
                                *map->m_next_pgofs =
                                        f2fs_get_next_page_offset(&dn, pgofs);
                        if (map->m_next_extent)
                                *map->m_next_extent =
                                        f2fs_get_next_page_offset(&dn, pgofs);
                }
                goto unlock_out;
        }

        start_pgofs = pgofs;
        prealloc = 0;
        last_ofs_in_node = ofs_in_node = dn.ofs_in_node;
        end_offset = ADDRS_PER_PAGE(dn.node_page, inode);

next_block:
        blkaddr = datablock_addr(dn.inode, dn.node_page, dn.ofs_in_node);

        if (__is_valid_data_blkaddr(blkaddr) &&
                !f2fs_is_valid_blkaddr(sbi, blkaddr, DATA_GENERIC_ENHANCE)) {
                err = -EFSCORRUPTED;
                goto sync_out;
        }

        if (__is_valid_data_blkaddr(blkaddr)) {
                /* use out-place-update for driect IO under LFS mode */
                if (test_opt(sbi, LFS) && flag == F2FS_GET_BLOCK_DIO &&
                                                        map->m_may_create) {
                        err = __allocate_data_block(&dn, map->m_seg_type);
                        if (err)
                                goto sync_out;
                        blkaddr = dn.data_blkaddr;
                        set_inode_flag(inode, FI_APPEND_WRITE);
                }
        } else {
                if (create) {
                        if (unlikely(f2fs_cp_error(sbi))) {
                                err = -EIO;
                                goto sync_out;
                        }
                        if (flag == F2FS_GET_BLOCK_PRE_AIO) {
                                if (blkaddr == NULL_ADDR) {
                                        prealloc++;
                                        last_ofs_in_node = dn.ofs_in_node;
                                }
                        } else {
                                WARN_ON(flag != F2FS_GET_BLOCK_PRE_DIO &&
                                        flag != F2FS_GET_BLOCK_DIO);
                                err = __allocate_data_block(&dn,
                                                        map->m_seg_type);
                                if (!err)
                                        set_inode_flag(inode, FI_APPEND_WRITE);
                        }
                        if (err)
                                goto sync_out;
                        map->m_flags |= F2FS_MAP_NEW;
                        blkaddr = dn.data_blkaddr;
                } else {
                        if (flag == F2FS_GET_BLOCK_BMAP) {
                                map->m_pblk = 0;
                                goto sync_out;
                        }
                        if (flag == F2FS_GET_BLOCK_PRECACHE)
                                goto sync_out;
                        if (flag == F2FS_GET_BLOCK_FIEMAP &&
                                                blkaddr == NULL_ADDR) {
                                if (map->m_next_pgofs)
                                        *map->m_next_pgofs = pgofs + 1;
                                goto sync_out;
                        }
                        if (flag != F2FS_GET_BLOCK_FIEMAP) {
                                /* for defragment case */
                                if (map->m_next_pgofs)
                                        *map->m_next_pgofs = pgofs + 1;
                                goto sync_out;
                        }
                }
        }

        if (flag == F2FS_GET_BLOCK_PRE_AIO)
                goto skip;

        if (map->m_len == 0) {
                /* preallocated unwritten block should be mapped for fiemap. */
                if (blkaddr == NEW_ADDR)
                        map->m_flags |= F2FS_MAP_UNWRITTEN;
                map->m_flags |= F2FS_MAP_MAPPED;

                map->m_pblk = blkaddr;
                map->m_len = 1;
        } else if ((map->m_pblk != NEW_ADDR &&
                        blkaddr == (map->m_pblk + ofs)) ||
                        (map->m_pblk == NEW_ADDR && blkaddr == NEW_ADDR) ||
                        flag == F2FS_GET_BLOCK_PRE_DIO) {
                ofs++;
                map->m_len++;
        } else {
                goto sync_out;
        }

skip:
        dn.ofs_in_node++;
        pgofs++;

        /* preallocate blocks in batch for one dnode page */
        if (flag == F2FS_GET_BLOCK_PRE_AIO &&
                        (pgofs == end || dn.ofs_in_node == end_offset)) {

                dn.ofs_in_node = ofs_in_node;
                err = f2fs_reserve_new_blocks(&dn, prealloc);
                if (err)
                        goto sync_out;

                map->m_len += dn.ofs_in_node - ofs_in_node;
                if (prealloc && dn.ofs_in_node != last_ofs_in_node + 1) {
                        err = -ENOSPC;
                        goto sync_out;
                }
                dn.ofs_in_node = end_offset;
        }

        if (pgofs >= end)
                goto sync_out;
        else if (dn.ofs_in_node < end_offset)
                goto next_block;

        if (flag == F2FS_GET_BLOCK_PRECACHE) {
                if (map->m_flags & F2FS_MAP_MAPPED) {
                        unsigned int ofs = start_pgofs - map->m_lblk;

                        f2fs_update_extent_cache_range(&dn,
                                start_pgofs, map->m_pblk + ofs,
                                map->m_len - ofs);
                }
        }

        f2fs_put_dnode(&dn);

        if (map->m_may_create) {
                __do_map_lock(sbi, flag, false);
                f2fs_balance_fs(sbi, dn.node_changed);
        }
        goto next_dnode;

sync_out:

        /* for hardware encryption, but to avoid potential issue in future */
        if (flag == F2FS_GET_BLOCK_DIO && map->m_flags & F2FS_MAP_MAPPED)
                f2fs_wait_on_block_writeback_range(inode,
                                                map->m_pblk, map->m_len);

        if (flag == F2FS_GET_BLOCK_PRECACHE) {
                if (map->m_flags & F2FS_MAP_MAPPED) {
                        unsigned int ofs = start_pgofs - map->m_lblk;

                        f2fs_update_extent_cache_range(&dn,
                                start_pgofs, map->m_pblk + ofs,
                                map->m_len - ofs);
                }
                if (map->m_next_extent)
                        *map->m_next_extent = pgofs + 1;
        }
        f2fs_put_dnode(&dn);
unlock_out:
        if (map->m_may_create) {
                __do_map_lock(sbi, flag, false);
                f2fs_balance_fs(sbi, dn.node_changed);
        }
out:
        trace_f2fs_map_blocks(inode, map, err);
        return err;
}

bool f2fs_overwrite_io(struct inode *inode, loff_t pos, size_t len)
{
        struct f2fs_map_blocks map;
        block_t last_lblk;
        int err;

        if (pos + len > i_size_read(inode))
                return false;

        map.m_lblk = F2FS_BYTES_TO_BLK(pos);
        map.m_next_pgofs = NULL;
        map.m_next_extent = NULL;
        map.m_seg_type = NO_CHECK_TYPE;
        map.m_may_create = false;
        last_lblk = F2FS_BLK_ALIGN(pos + len);

        while (map.m_lblk < last_lblk) {
                map.m_len = last_lblk - map.m_lblk;
                err = f2fs_map_blocks(inode, &map, 0, F2FS_GET_BLOCK_DEFAULT);
                if (err || map.m_len == 0)
                        return false;
                map.m_lblk += map.m_len;
        }
        return true;
}

static int __get_data_block(struct inode *inode, sector_t iblock,
                        struct buffer_head *bh, int create, int flag,
                        pgoff_t *next_pgofs, int seg_type, bool may_write)
{
        struct f2fs_map_blocks map;
        int err;

        map.m_lblk = iblock;
        map.m_len = bh->b_size >> inode->i_blkbits;
        map.m_next_pgofs = next_pgofs;
        map.m_next_extent = NULL;
        map.m_seg_type = seg_type;
        map.m_may_create = may_write;

        err = f2fs_map_blocks(inode, &map, create, flag);
        if (!err) {
                map_bh(bh, inode->i_sb, map.m_pblk);
                bh->b_state = (bh->b_state & ~F2FS_MAP_FLAGS) | map.m_flags;
                bh->b_size = (u64)map.m_len << inode->i_blkbits;
        }
        return err;
}

static int get_data_block(struct inode *inode, sector_t iblock,
                        struct buffer_head *bh_result, int create, int flag,
                        pgoff_t *next_pgofs)
{
        return __get_data_block(inode, iblock, bh_result, create,
                                                        flag, next_pgofs,
                                                        NO_CHECK_TYPE, create);
}

static int get_data_block_dio_write(struct inode *inode, sector_t iblock,
                        struct buffer_head *bh_result, int create)
{
        return __get_data_block(inode, iblock, bh_result, create,
                                F2FS_GET_BLOCK_DIO, NULL,
                                f2fs_rw_hint_to_seg_type(inode->i_write_hint),
                                IS_SWAPFILE(inode) ? false : true);
}

static int get_data_block_dio(struct inode *inode, sector_t iblock,
                        struct buffer_head *bh_result, int create)
{
        return __get_data_block(inode, iblock, bh_result, create,
                                F2FS_GET_BLOCK_DIO, NULL,
                                f2fs_rw_hint_to_seg_type(inode->i_write_hint),
                                false);
}

static int get_data_block_bmap(struct inode *inode, sector_t iblock,
                        struct buffer_head *bh_result, int create)
{
        /* Block number less than F2FS MAX BLOCKS */
        if (unlikely(iblock >= F2FS_I_SB(inode)->max_file_blocks))
                return -EFBIG;

        return __get_data_block(inode, iblock, bh_result, create,
                                                F2FS_GET_BLOCK_BMAP, NULL,
                                                NO_CHECK_TYPE, create);
}

static inline sector_t logical_to_blk(struct inode *inode, loff_t offset)
{
        return (offset >> inode->i_blkbits);
}

static inline loff_t blk_to_logical(struct inode *inode, sector_t blk)
{
        return (blk << inode->i_blkbits);
}

static int f2fs_xattr_fiemap(struct inode *inode,
                                struct fiemap_extent_info *fieinfo)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct page *page;
        struct node_info ni;
        __u64 phys = 0, len;
        __u32 flags;
        nid_t xnid = F2FS_I(inode)->i_xattr_nid;
        int err = 0;

        if (f2fs_has_inline_xattr(inode)) {
                int offset;

                page = f2fs_grab_cache_page(NODE_MAPPING(sbi),
                                                inode->i_ino, false);
                if (!page)
                        return -ENOMEM;

                err = f2fs_get_node_info(sbi, inode->i_ino, &ni);
                if (err) {
                        f2fs_put_page(page, 1);
                        return err;
                }

                phys = (__u64)blk_to_logical(inode, ni.blk_addr);
                offset = offsetof(struct f2fs_inode, i_addr) +
                                        sizeof(__le32) * (DEF_ADDRS_PER_INODE -
                                        get_inline_xattr_addrs(inode));

                phys += offset;
                len = inline_xattr_size(inode);

                f2fs_put_page(page, 1);

                flags = FIEMAP_EXTENT_DATA_INLINE | FIEMAP_EXTENT_NOT_ALIGNED;

                if (!xnid)
                        flags |= FIEMAP_EXTENT_LAST;

                err = fiemap_fill_next_extent(fieinfo, 0, phys, len, flags);
                if (err || err == 1)
                        return err;
        }

        if (xnid) {
                page = f2fs_grab_cache_page(NODE_MAPPING(sbi), xnid, false);
                if (!page)
                        return -ENOMEM;

                err = f2fs_get_node_info(sbi, xnid, &ni);
                if (err) {
                        f2fs_put_page(page, 1);
                        return err;
                }

                phys = (__u64)blk_to_logical(inode, ni.blk_addr);
                len = inode->i_sb->s_blocksize;

                f2fs_put_page(page, 1);

                flags = FIEMAP_EXTENT_LAST;
        }

        if (phys)
                err = fiemap_fill_next_extent(fieinfo, 0, phys, len, flags);

        return (err < 0 ? err : 0);
}

int f2fs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                u64 start, u64 len)
{
        struct buffer_head map_bh;
        sector_t start_blk, last_blk;
        pgoff_t next_pgofs;
        u64 logical = 0, phys = 0, size = 0;
        u32 flags = 0;
        int ret = 0;

        if (fieinfo->fi_flags & FIEMAP_FLAG_CACHE) {
                ret = f2fs_precache_extents(inode);
                if (ret)
                        return ret;
        }

        ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC | FIEMAP_FLAG_XATTR);
        if (ret)
                return ret;

        inode_lock(inode);

        if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR) {
                ret = f2fs_xattr_fiemap(inode, fieinfo);
                goto out;
        }

        if (f2fs_has_inline_data(inode) || f2fs_has_inline_dentry(inode)) {
                ret = f2fs_inline_data_fiemap(inode, fieinfo, start, len);
                if (ret != -EAGAIN)
                        goto out;
        }

        if (logical_to_blk(inode, len) == 0)
                len = blk_to_logical(inode, 1);

        start_blk = logical_to_blk(inode, start);
        last_blk = logical_to_blk(inode, start + len - 1);

next:
        memset(&map_bh, 0, sizeof(struct buffer_head));
        map_bh.b_size = len;

        ret = get_data_block(inode, start_blk, &map_bh, 0,
                                        F2FS_GET_BLOCK_FIEMAP, &next_pgofs);
        if (ret)
                goto out;

        /* HOLE */
        if (!buffer_mapped(&map_bh)) {
                start_blk = next_pgofs;

                if (blk_to_logical(inode, start_blk) < blk_to_logical(inode,
                                        F2FS_I_SB(inode)->max_file_blocks))
                        goto prep_next;

                flags |= FIEMAP_EXTENT_LAST;
        }

        if (size) {
                if (IS_ENCRYPTED(inode))
                        flags |= FIEMAP_EXTENT_DATA_ENCRYPTED;

                ret = fiemap_fill_next_extent(fieinfo, logical,
                                phys, size, flags);
        }

        if (start_blk > last_blk || ret)
                goto out;

        logical = blk_to_logical(inode, start_blk);
        phys = blk_to_logical(inode, map_bh.b_blocknr);
        size = map_bh.b_size;
        flags = 0;
        if (buffer_unwritten(&map_bh))
                flags = FIEMAP_EXTENT_UNWRITTEN;

        start_blk += logical_to_blk(inode, size);

prep_next:
        cond_resched();
        if (fatal_signal_pending(current))
                ret = -EINTR;
        else
                goto next;
out:
        if (ret == 1)
                ret = 0;

        inode_unlock(inode);
        return ret;
}

static inline loff_t f2fs_readpage_limit(struct inode *inode)
{
        if (IS_ENABLED(CONFIG_FS_VERITY) &&
            (IS_VERITY(inode) || f2fs_verity_in_progress(inode)))
                return inode->i_sb->s_maxbytes;

        return i_size_read(inode);
}

static int f2fs_read_single_page(struct inode *inode, struct page *page,
                                        unsigned nr_pages,
                                        struct f2fs_map_blocks *map,
                                        struct bio **bio_ret,
                                        sector_t *last_block_in_bio,
                                        bool is_readahead)
{
        struct bio *bio = *bio_ret;
        const unsigned blkbits = inode->i_blkbits;
        const unsigned blocksize = 1 << blkbits;
        sector_t block_in_file;
        sector_t last_block;
        sector_t last_block_in_file;
        sector_t block_nr;
        int ret = 0;

        block_in_file = (sector_t)page_index(page);
        last_block = block_in_file + nr_pages;
        last_block_in_file = (f2fs_readpage_limit(inode) + blocksize - 1) >>
                                                        blkbits;
        if (last_block > last_block_in_file)
                last_block = last_block_in_file;

        /* just zeroing out page which is beyond EOF */
        if (block_in_file >= last_block)
                goto zero_out;
        /*
         * Map blocks using the previous result first.
         */
        if ((map->m_flags & F2FS_MAP_MAPPED) &&
                        block_in_file > map->m_lblk &&
                        block_in_file < (map->m_lblk + map->m_len))
                goto got_it;

        /*
         * Then do more f2fs_map_blocks() calls until we are
         * done with this page.
         */
        map->m_lblk = block_in_file;
        map->m_len = last_block - block_in_file;

        ret = f2fs_map_blocks(inode, map, 0, F2FS_GET_BLOCK_DEFAULT);
        if (ret)
                goto out;
got_it:
        if ((map->m_flags & F2FS_MAP_MAPPED)) {
                block_nr = map->m_pblk + block_in_file - map->m_lblk;
                SetPageMappedToDisk(page);

                if (!PageUptodate(page) && (!PageSwapCache(page) &&
                                        !cleancache_get_page(page))) {
                        SetPageUptodate(page);
                        goto confused;
                }

                if (!f2fs_is_valid_blkaddr(F2FS_I_SB(inode), block_nr,
                                                DATA_GENERIC_ENHANCE_READ)) {
                        ret = -EFSCORRUPTED;
                        goto out;
                }
        } else {
zero_out:
                zero_user_segment(page, 0, PAGE_SIZE);
                if (f2fs_need_verity(inode, page->index) &&
                    !fsverity_verify_page(page)) {
                        ret = -EIO;
                        goto out;
                }
                if (!PageUptodate(page))
                        SetPageUptodate(page);
                unlock_page(page);
                goto out;
        }

        /*
         * This page will go to BIO.  Do we need to send this
         * BIO off first?
         */
        if (bio && !page_is_mergeable(F2FS_I_SB(inode), bio,
                                *last_block_in_bio, block_nr)) {
submit_and_realloc:
                __submit_bio(F2FS_I_SB(inode), bio, DATA);
                bio = NULL;
        }
        if (bio == NULL) {
                bio = f2fs_grab_read_bio(inode, block_nr, nr_pages,
                                is_readahead ? REQ_RAHEAD : 0, page->index);
                if (IS_ERR(bio)) {
                        ret = PTR_ERR(bio);
                        bio = NULL;
                        goto out;
                }
        }

        /*
         * If the page is under writeback, we need to wait for
         * its completion to see the correct decrypted data.
         */
        f2fs_wait_on_block_writeback(inode, block_nr);

        if (bio_add_page(bio, page, blocksize, 0) < blocksize)
                goto submit_and_realloc;

        inc_page_count(F2FS_I_SB(inode), F2FS_RD_DATA);
        ClearPageError(page);
        *last_block_in_bio = block_nr;
        goto out;
confused:
        if (bio) {
                __submit_bio(F2FS_I_SB(inode), bio, DATA);
                bio = NULL;
        }
        unlock_page(page);
out:
        *bio_ret = bio;
        return ret;
}

/*
 * This function was originally taken from fs/mpage.c, and customized for f2fs.
 * Major change was from block_size == page_size in f2fs by default.
 *
 * Note that the aops->readpages() function is ONLY used for read-ahead. If
 * this function ever deviates from doing just read-ahead, it should either
 * use ->readpage() or do the necessary surgery to decouple ->readpages()
 * from read-ahead.
 */
static int f2fs_mpage_readpages(struct address_space *mapping,
                        struct list_head *pages, struct page *page,
                        unsigned nr_pages, bool is_readahead)
{
        struct bio *bio = NULL;
        sector_t last_block_in_bio = 0;
        struct inode *inode = mapping->host;
        struct f2fs_map_blocks map;
        int ret = 0;

        map.m_pblk = 0;
        map.m_lblk = 0;
        map.m_len = 0;
        map.m_flags = 0;
        map.m_next_pgofs = NULL;
        map.m_next_extent = NULL;
        map.m_seg_type = NO_CHECK_TYPE;
        map.m_may_create = false;

        for (; nr_pages; nr_pages--) {
                if (pages) {
                        page = list_last_entry(pages, struct page, lru);

                        prefetchw(&page->flags);
                        list_del(&page->lru);
                        if (add_to_page_cache_lru(page, mapping,
                                                  page_index(page),
                                                  readahead_gfp_mask(mapping)))
                                goto next_page;
                }

                ret = f2fs_read_single_page(inode, page, nr_pages, &map, &bio,
                                        &last_block_in_bio, is_readahead);
                if (ret) {
                        SetPageError(page);
                        zero_user_segment(page, 0, PAGE_SIZE);
                        unlock_page(page);
                }
next_page:
                if (pages)
                        put_page(page);
        }
        BUG_ON(pages && !list_empty(pages));
        if (bio)
                __submit_bio(F2FS_I_SB(inode), bio, DATA);
        return pages ? 0 : ret;
}

static int f2fs_read_data_page(struct file *file, struct page *page)
{
        struct inode *inode = page_file_mapping(page)->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 = f2fs_mpage_readpages(page_file_mapping(page),
                                                NULL, page, 1, false);
        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 = mapping->host;
        struct page *page = list_last_entry(pages, struct page, lru);

        trace_f2fs_readpages(inode, page, nr_pages);

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

        return f2fs_mpage_readpages(mapping, pages, NULL, nr_pages, true);
}

static int encrypt_one_page(struct f2fs_io_info *fio)
{
        struct inode *inode = fio->page->mapping->host;
        struct page *mpage;
        gfp_t gfp_flags = GFP_NOFS;

        if (!f2fs_encrypted_file(inode))
                return 0;

        /* wait for GCed page writeback via META_MAPPING */
        f2fs_wait_on_block_writeback(inode, fio->old_blkaddr);

retry_encrypt:
        fio->encrypted_page = fscrypt_encrypt_pagecache_blocks(fio->page,
                                                               PAGE_SIZE, 0,
                                                               gfp_flags);
        if (IS_ERR(fio->encrypted_page)) {
                /* flush pending IOs and wait for a while in the ENOMEM case */
                if (PTR_ERR(fio->encrypted_page) == -ENOMEM) {
                        f2fs_flush_merged_writes(fio->sbi);
                        congestion_wait(BLK_RW_ASYNC, HZ/50);
                        gfp_flags |= __GFP_NOFAIL;
                        goto retry_encrypt;
                }
                return PTR_ERR(fio->encrypted_page);
        }

        mpage = find_lock_page(META_MAPPING(fio->sbi), fio->old_blkaddr);
        if (mpage) {
                if (PageUptodate(mpage))
                        memcpy(page_address(mpage),
                                page_address(fio->encrypted_page), PAGE_SIZE);
                f2fs_put_page(mpage, 1);
        }
        return 0;
}

static inline bool check_inplace_update_policy(struct inode *inode,
                                struct f2fs_io_info *fio)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        unsigned int policy = SM_I(sbi)->ipu_policy;

        if (policy & (0x1 << F2FS_IPU_FORCE))
                return true;
        if (policy & (0x1 << F2FS_IPU_SSR) && f2fs_need_SSR(sbi))
                return true;
        if (policy & (0x1 << F2FS_IPU_UTIL) &&
                        utilization(sbi) > SM_I(sbi)->min_ipu_util)
                return true;
        if (policy & (0x1 << F2FS_IPU_SSR_UTIL) && f2fs_need_SSR(sbi) &&
                        utilization(sbi) > SM_I(sbi)->min_ipu_util)
                return true;

        /*
         * IPU for rewrite async pages
         */
        if (policy & (0x1 << F2FS_IPU_ASYNC) &&
                        fio && fio->op == REQ_OP_WRITE &&
                        !(fio->op_flags & REQ_SYNC) &&
                        !IS_ENCRYPTED(inode))
                return true;

        /* this is only set during fdatasync */
        if (policy & (0x1 << F2FS_IPU_FSYNC) &&
                        is_inode_flag_set(inode, FI_NEED_IPU))
                return true;

        if (unlikely(fio && is_sbi_flag_set(sbi, SBI_CP_DISABLED) &&
                        !f2fs_is_checkpointed_data(sbi, fio->old_blkaddr)))
                return true;

        return false;
}

bool f2fs_should_update_inplace(struct inode *inode, struct f2fs_io_info *fio)
{
        if (f2fs_is_pinned_file(inode))
                return true;

        /* if this is cold file, we should overwrite to avoid fragmentation */
        if (file_is_cold(inode))
                return true;

        return check_inplace_update_policy(inode, fio);
}

bool f2fs_should_update_outplace(struct inode *inode, struct f2fs_io_info *fio)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);

        if (test_opt(sbi, LFS))
                return true;
        if (S_ISDIR(inode->i_mode))
                return true;
        if (IS_NOQUOTA(inode))
                return true;
        if (f2fs_is_atomic_file(inode))
                return true;
        if (fio) {
                if (is_cold_data(fio->page))
                        return true;
                if (IS_ATOMIC_WRITTEN_PAGE(fio->page))
                        return true;
                if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED) &&
                        f2fs_is_checkpointed_data(sbi, fio->old_blkaddr)))
                        return true;
        }
        return false;
}

static inline bool need_inplace_update(struct f2fs_io_info *fio)
{
        struct inode *inode = fio->page->mapping->host;

        if (f2fs_should_update_outplace(inode, fio))
                return false;

        return f2fs_should_update_inplace(inode, fio);
}

int f2fs_do_write_data_page(struct f2fs_io_info *fio)
{
        struct page *page = fio->page;
        struct inode *inode = page->mapping->host;
        struct dnode_of_data dn;
        struct extent_info ei = {0,0,0};
        struct node_info ni;
        bool ipu_force = false;
        int err = 0;

        set_new_dnode(&dn, inode, NULL, NULL, 0);
        if (need_inplace_update(fio) &&
                        f2fs_lookup_extent_cache(inode, page->index, &ei)) {
                fio->old_blkaddr = ei.blk + page->index - ei.fofs;

                if (!f2fs_is_valid_blkaddr(fio->sbi, fio->old_blkaddr,
                                                DATA_GENERIC_ENHANCE))
                        return -EFSCORRUPTED;

                ipu_force = true;
                fio->need_lock = LOCK_DONE;
                goto got_it;

        }

        /* Deadlock due to between page->lock and f2fs_lock_op */
        if (fio->need_lock == LOCK_REQ && !f2fs_trylock_op(fio->sbi))
                return -EAGAIN;

        err = f2fs_get_dnode_of_data(&dn, page->index, LOOKUP_NODE);
        if (err)
                goto out;

        fio->old_blkaddr = dn.data_blkaddr;

        /* This page is already truncated */
        if (fio->old_blkaddr == NULL_ADDR) {
                ClearPageUptodate(page);
                clear_cold_data(page);
                goto out_writepage;
        }
got_it:
        if (__is_valid_data_blkaddr(fio->old_blkaddr) &&
                !f2fs_is_valid_blkaddr(fio->sbi, fio->old_blkaddr,
                                                DATA_GENERIC_ENHANCE)) {
                err = -EFSCORRUPTED;
                goto out_writepage;
        }
        /*
         * If current allocation needs SSR,
         * it had better in-place writes for updated data.
         */
        if (ipu_force ||
                (__is_valid_data_blkaddr(fio->old_blkaddr) &&
                                        need_inplace_update(fio))) {
                err = encrypt_one_page(fio);
                if (err)
                        goto out_writepage;

                set_page_writeback(page);
                ClearPageError(page);
                f2fs_put_dnode(&dn);
                if (fio->need_lock == LOCK_REQ)
                        f2fs_unlock_op(fio->sbi);
                err = f2fs_inplace_write_data(fio);
                if (err) {
                        if (f2fs_encrypted_file(inode))
                                fscrypt_finalize_bounce_page(&fio->encrypted_page);
                        if (PageWriteback(page))
                                end_page_writeback(page);
                } else {
                        set_inode_flag(inode, FI_UPDATE_WRITE);
                }
                trace_f2fs_do_write_data_page(fio->page, IPU);
                return err;
        }

        if (fio->need_lock == LOCK_RETRY) {
                if (!f2fs_trylock_op(fio->sbi)) {
                        err = -EAGAIN;
                        goto out_writepage;
                }
                fio->need_lock = LOCK_REQ;
        }

        err = f2fs_get_node_info(fio->sbi, dn.nid, &ni);
        if (err)
                goto out_writepage;

        fio->version = ni.version;

        err = encrypt_one_page(fio);
        if (err)
                goto out_writepage;

        set_page_writeback(page);
        ClearPageError(page);

        /* LFS mode write path */
        f2fs_outplace_write_data(&dn, fio);
        trace_f2fs_do_write_data_page(page, OPU);
        set_inode_flag(inode, FI_APPEND_WRITE);
        if (page->index == 0)
                set_inode_flag(inode, FI_FIRST_BLOCK_WRITTEN);
out_writepage:
        f2fs_put_dnode(&dn);
out:
        if (fio->need_lock == LOCK_REQ)
                f2fs_unlock_op(fio->sbi);
        return err;
}

static int __write_data_page(struct page *page, bool *submitted,
                                struct bio **bio,
                                sector_t *last_block,
                                struct writeback_control *wbc,
                                enum iostat_type io_type)
{
        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_SHIFT;
        loff_t psize = (page->index + 1) << PAGE_SHIFT;
        unsigned offset = 0;
        bool need_balance_fs = false;
        int err = 0;
        struct f2fs_io_info fio = {
                .sbi = sbi,
                .ino = inode->i_ino,
                .type = DATA,
                .op = REQ_OP_WRITE,
                .op_flags = wbc_to_write_flags(wbc),
                .old_blkaddr = NULL_ADDR,
                .page = page,
                .encrypted_page = NULL,
                .submitted = false,
                .need_lock = LOCK_RETRY,
                .io_type = io_type,
                .io_wbc = wbc,
                .bio = bio,
                .last_block = last_block,
        };

        trace_f2fs_writepage(page, DATA);

        /* we should bypass data pages to proceed the kworkder jobs */
        if (unlikely(f2fs_cp_error(sbi))) {
                mapping_set_error(page->mapping, -EIO);
                /*
                 * don't drop any dirty dentry pages for keeping lastest
                 * directory structure.
                 */
                if (S_ISDIR(inode->i_mode))
                        goto redirty_out;
                goto out;
        }

        if (unlikely(is_sbi_flag_set(sbi, SBI_POR_DOING)))
                goto redirty_out;

        if (page->index < end_index || f2fs_verity_in_progress(inode))
                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_SIZE - 1);
        if ((page->index >= end_index + 1) || !offset)
                goto out;

        zero_user_segment(page, offset, PAGE_SIZE);
write:
        if (f2fs_is_drop_cache(inode))
                goto out;
        /* we should not write 0'th page having journal header */
        if (f2fs_is_volatile_file(inode) && (!page->index ||
                        (!wbc->for_reclaim &&
                        f2fs_available_free_memory(sbi, BASE_CHECK))))
                goto redirty_out;

        /* Dentry blocks are controlled by checkpoint */
        if (S_ISDIR(inode->i_mode)) {
                fio.need_lock = LOCK_DONE;
                err = f2fs_do_write_data_page(&fio);
                goto done;
        }

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

        err = -EAGAIN;
        if (f2fs_has_inline_data(inode)) {
                err = f2fs_write_inline_data(inode, page);
                if (!err)
                        goto out;
        }

        if (err == -EAGAIN) {
                err = f2fs_do_write_data_page(&fio);
                if (err == -EAGAIN) {
                        fio.need_lock = LOCK_REQ;
                        err = f2fs_do_write_data_page(&fio);
                }
        }

        if (err) {
                file_set_keep_isize(inode);
        } else {
                down_write(&F2FS_I(inode)->i_sem);
                if (F2FS_I(inode)->last_disk_size < psize)
                        F2FS_I(inode)->last_disk_size = psize;
                up_write(&F2FS_I(inode)->i_sem);
        }

done:
        if (err && err != -ENOENT)
                goto redirty_out;

out:
        inode_dec_dirty_pages(inode);
        if (err) {
                ClearPageUptodate(page);
                clear_cold_data(page);
        }

        if (wbc->for_reclaim) {
                f2fs_submit_merged_write_cond(sbi, NULL, page, 0, DATA);
                clear_inode_flag(inode, FI_HOT_DATA);
                f2fs_remove_dirty_inode(inode);
                submitted = NULL;
        }

        unlock_page(page);
        if (!S_ISDIR(inode->i_mode) && !IS_NOQUOTA(inode) &&
                                        !F2FS_I(inode)->cp_task) {
                f2fs_submit_ipu_bio(sbi, bio, page);
                f2fs_balance_fs(sbi, need_balance_fs);
        }

        if (unlikely(f2fs_cp_error(sbi))) {
                f2fs_submit_ipu_bio(sbi, bio, page);
                f2fs_submit_merged_write(sbi, DATA);
                submitted = NULL;
        }

        if (submitted)
                *submitted = fio.submitted;

        return 0;

redirty_out:
        redirty_page_for_writepage(wbc, page);
        /*
         * pageout() in MM traslates EAGAIN, so calls handle_write_error()
         * -> mapping_set_error() -> set_bit(AS_EIO, ...).
         * file_write_and_wait_range() will see EIO error, which is critical
         * to return value of fsync() followed by atomic_write failure to user.
         */
        if (!err || wbc->for_reclaim)
                return AOP_WRITEPAGE_ACTIVATE;
        unlock_page(page);
        return err;
}

static int f2fs_write_data_page(struct page *page,
                                        struct writeback_control *wbc)
{
        return __write_data_page(page, NULL, NULL, NULL, wbc, FS_DATA_IO);
}

/*
 * This function was copied from write_cche_pages from mm/page-writeback.c.
 * The major change is making write step of cold data page separately from
 * warm/hot data page.
 */
static int f2fs_write_cache_pages(struct address_space *mapping,
                                        struct writeback_control *wbc,
                                        enum iostat_type io_type)
{
        int ret = 0;
        int done = 0;
        struct pagevec pvec;
        struct f2fs_sb_info *sbi = F2FS_M_SB(mapping);
        struct bio *bio = NULL;
        sector_t last_block;
        int nr_pages;
        pgoff_t uninitialized_var(writeback_index);
        pgoff_t index;
        pgoff_t end;            /* Inclusive */
        pgoff_t done_index;
        int cycled;
        int range_whole = 0;
        xa_mark_t tag;
        int nwritten = 0;

        pagevec_init(&pvec);

        if (get_dirty_pages(mapping->host) <=
                                SM_I(F2FS_M_SB(mapping))->min_hot_blocks)
                set_inode_flag(mapping->host, FI_HOT_DATA);
        else
                clear_inode_flag(mapping->host, FI_HOT_DATA);

        if (wbc->range_cyclic) {
                writeback_index = mapping->writeback_index; /* prev offset */
                index = writeback_index;
                if (index == 0)
                        cycled = 1;
                else
                        cycled = 0;
                end = -1;
        } else {
                index = wbc->range_start >> PAGE_SHIFT;
                end = wbc->range_end >> PAGE_SHIFT;
                if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
                        range_whole = 1;
                cycled = 1; /* ignore range_cyclic tests */
        }
        if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
                tag = PAGECACHE_TAG_TOWRITE;
        else
                tag = PAGECACHE_TAG_DIRTY;
retry:
        if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
                tag_pages_for_writeback(mapping, index, end);
        done_index = index;
        while (!done && (index <= end)) {
                int i;

                nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end,
                                tag);
                if (nr_pages == 0)
                        break;

                for (i = 0; i < nr_pages; i++) {
                        struct page *page = pvec.pages[i];
                        bool submitted = false;

                        /* give a priority to WB_SYNC threads */
                        if (atomic_read(&sbi->wb_sync_req[DATA]) &&
                                        wbc->sync_mode == WB_SYNC_NONE) {
                                done = 1;
                                break;
                        }

                        done_index = page->index;
retry_write:
                        lock_page(page);

                        if (unlikely(page->mapping != mapping)) {
continue_unlock:
                                unlock_page(page);
                                continue;
                        }

                        if (!PageDirty(page)) {
                                /* someone wrote it for us */
                                goto continue_unlock;
                        }

                        if (PageWriteback(page)) {
                                if (wbc->sync_mode != WB_SYNC_NONE) {
                                        f2fs_wait_on_page_writeback(page,
                                                        DATA, true, true);
                                        f2fs_submit_ipu_bio(sbi, &bio, page);
                                } else {
                                        goto continue_unlock;
                                }
                        }

                        if (!clear_page_dirty_for_io(page))
                                goto continue_unlock;

                        ret = __write_data_page(page, &submitted, &bio,
                                        &last_block, wbc, io_type);
                        if (unlikely(ret)) {
                                /*
                                 * keep nr_to_write, since vfs uses this to
                                 * get # of written pages.
                                 */
                                if (ret == AOP_WRITEPAGE_ACTIVATE) {
                                        unlock_page(page);
                                        ret = 0;
                                        continue;
                                } else if (ret == -EAGAIN) {
                                        ret = 0;
                                        if (wbc->sync_mode == WB_SYNC_ALL) {
                                                cond_resched();
                                                congestion_wait(BLK_RW_ASYNC,
                                                                        HZ/50);
                                                goto retry_write;
                                        }
                                        continue;
                                }
                                done_index = page->index + 1;
                                done = 1;
                                break;
                        } else if (submitted) {
                                nwritten++;
                        }

                        if (--wbc->nr_to_write <= 0 &&
                                        wbc->sync_mode == WB_SYNC_NONE) {
                                done = 1;
                                break;
                        }
                }
                pagevec_release(&pvec);
                cond_resched();
        }

        if (!cycled && !done) {
                cycled = 1;
                index = 0;
                end = writeback_index - 1;
                goto retry;
        }
        if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
                mapping->writeback_index = done_index;

        if (nwritten)
                f2fs_submit_merged_write_cond(F2FS_M_SB(mapping), mapping->host,
                                                                NULL, 0, DATA);
        /* submit cached bio of IPU write */
        if (bio)
                __submit_bio(sbi, bio, DATA);

        return ret;
}

static inline bool __should_serialize_io(struct inode *inode,
                                        struct writeback_control *wbc)
{
        if (!S_ISREG(inode->i_mode))
                return false;
        if (IS_NOQUOTA(inode))
                return false;
        /* to avoid deadlock in path of data flush */
        if (F2FS_I(inode)->cp_task)
                return false;
        if (wbc->sync_mode != WB_SYNC_ALL)
                return true;
        if (get_dirty_pages(inode) >= SM_I(F2FS_I_SB(inode))->min_seq_blocks)
                return true;
        return false;
}

static int __f2fs_write_data_pages(struct address_space *mapping,
                                                struct writeback_control *wbc,
                                                enum iostat_type io_type)
{
        struct inode *inode = mapping->host;
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct blk_plug plug;
        int ret;
        bool locked = false;

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

        /* skip writing if there is no dirty page in this inode */
        if (!get_dirty_pages(inode) && wbc->sync_mode == WB_SYNC_NONE)
                return 0;

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

        if ((S_ISDIR(inode->i_mode) || IS_NOQUOTA(inode)) &&
                        wbc->sync_mode == WB_SYNC_NONE &&
                        get_dirty_pages(inode) < nr_pages_to_skip(sbi, DATA) &&
                        f2fs_available_free_memory(sbi, DIRTY_DENTS))
                goto skip_write;

        /* skip writing during file defragment */
        if (is_inode_flag_set(inode, FI_DO_DEFRAG))
                goto skip_write;

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

        /* to avoid spliting IOs due to mixed WB_SYNC_ALL and WB_SYNC_NONE */
        if (wbc->sync_mode == WB_SYNC_ALL)
                atomic_inc(&sbi->wb_sync_req[DATA]);
        else if (atomic_read(&sbi->wb_sync_req[DATA]))
                goto skip_write;

        if (__should_serialize_io(inode, wbc)) {
                mutex_lock(&sbi->writepages);
                locked = true;
        }

        blk_start_plug(&plug);
        ret = f2fs_write_cache_pages(mapping, wbc, io_type);
        blk_finish_plug(&plug);

        if (locked)
                mutex_unlock(&sbi->writepages);

        if (wbc->sync_mode == WB_SYNC_ALL)
                atomic_dec(&sbi->wb_sync_req[DATA]);
        /*
         * if some pages were truncated, we cannot guarantee its mapping->host
         * to detect pending bios.
         */

        f2fs_remove_dirty_inode(inode);
        return ret;

skip_write:
        wbc->pages_skipped += get_dirty_pages(inode);
        trace_f2fs_writepages(mapping->host, wbc, DATA);
        return 0;
}

static int f2fs_write_data_pages(struct address_space *mapping,
                            struct writeback_control *wbc)
{
        struct inode *inode = mapping->host;

        return __f2fs_write_data_pages(mapping, wbc,
                        F2FS_I(inode)->cp_task == current ?
                        FS_CP_DATA_IO : FS_DATA_IO);
}

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

        /* In the fs-verity case, f2fs_end_enable_verity() does the truncate */
        if (to > i_size && !f2fs_verity_in_progress(inode)) {
                down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
                down_write(&F2FS_I(inode)->i_mmap_sem);

                truncate_pagecache(inode, i_size);
                if (!IS_NOQUOTA(inode))
                        f2fs_truncate_blocks(inode, i_size, true);

                up_write(&F2FS_I(inode)->i_mmap_sem);
                up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
        }
}

static int prepare_write_begin(struct f2fs_sb_info *sbi,
                        struct page *page, loff_t pos, unsigned len,
                        block_t *blk_addr, bool *node_changed)
{
        struct inode *inode = page->mapping->host;
        pgoff_t index = page->index;
        struct dnode_of_data dn;
        struct page *ipage;
        bool locked = false;
        struct extent_info ei = {0,0,0};
        int err = 0;
        int flag;

        /*
         * we already allocated all the blocks, so we don't need to get
         * the block addresses when there is no need to fill the page.
         */
        if (!f2fs_has_inline_data(inode) && len == PAGE_SIZE &&
            !is_inode_flag_set(inode, FI_NO_PREALLOC) &&
            !f2fs_verity_in_progress(inode))
                return 0;

        /* f2fs_lock_op avoids race between write CP and convert_inline_page */
        if (f2fs_has_inline_data(inode) && pos + len > MAX_INLINE_DATA(inode))
                flag = F2FS_GET_BLOCK_DEFAULT;
        else
                flag = F2FS_GET_BLOCK_PRE_AIO;

        if (f2fs_has_inline_data(inode) ||
                        (pos & PAGE_MASK) >= i_size_read(inode)) {
                __do_map_lock(sbi, flag, true);
                locked = true;
        }
restart:
        /* check inline_data */
        ipage = f2fs_get_node_page(sbi, inode->i_ino);
        if (IS_ERR(ipage)) {
                err = PTR_ERR(ipage);
                goto unlock_out;
        }

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

        if (f2fs_has_inline_data(inode)) {
                if (pos + len <= MAX_INLINE_DATA(inode)) {
                        f2fs_do_read_inline_data(page, ipage);
                        set_inode_flag(inode, FI_DATA_EXIST);
                        if (inode->i_nlink)
                                set_inline_node(ipage);
                } else {
                        err = f2fs_convert_inline_page(&dn, page);
                        if (err)
                                goto out;
                        if (dn.data_blkaddr == NULL_ADDR)
                                err = f2fs_get_block(&dn, index);
                }
        } else if (locked) {
                err = f2fs_get_block(&dn, index);
        } else {
                if (f2fs_lookup_extent_cache(inode, index, &ei)) {
                        dn.data_blkaddr = ei.blk + index - ei.fofs;
                } else {
                        /* hole case */
                        err = f2fs_get_dnode_of_data(&dn, index, LOOKUP_NODE);
                        if (err || dn.data_blkaddr == NULL_ADDR) {
                                f2fs_put_dnode(&dn);
                                __do_map_lock(sbi, F2FS_GET_BLOCK_PRE_AIO,
                                                                true);
                                WARN_ON(flag != F2FS_GET_BLOCK_PRE_AIO);
                                locked = true;
                                goto restart;
                        }
                }
        }

        /* convert_inline_page can make node_changed */
        *blk_addr = dn.data_blkaddr;
        *node_changed = dn.node_changed;
out:
        f2fs_put_dnode(&dn);
unlock_out:
        if (locked)
                __do_map_lock(sbi, flag, false);
        return err;
}

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 = NULL;
        pgoff_t index = ((unsigned long long) pos) >> PAGE_SHIFT;
        bool need_balance = false, drop_atomic = false;
        block_t blkaddr = NULL_ADDR;
        int err = 0;

        trace_f2fs_write_begin(inode, pos, len, flags);

        if (!f2fs_is_checkpoint_ready(sbi)) {
                err = -ENOSPC;
                goto fail;
        }

        if ((f2fs_is_atomic_file(inode) &&
                        !f2fs_available_free_memory(sbi, INMEM_PAGES)) ||
                        is_inode_flag_set(inode, FI_ATOMIC_REVOKE_REQUEST)) {
                err = -ENOMEM;
                drop_atomic = true;
                goto fail;
        }

        /*
         * 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:
        /*
         * Do not use grab_cache_page_write_begin() to avoid deadlock due to
         * wait_for_stable_page. Will wait that below with our IO control.
         */
        page = f2fs_pagecache_get_page(mapping, index,
                                FGP_LOCK | FGP_WRITE | FGP_CREAT, GFP_NOFS);
        if (!page) {
                err = -ENOMEM;
                goto fail;
        }

        *pagep = page;

        err = prepare_write_begin(sbi, page, pos, len,
                                        &blkaddr, &need_balance);
        if (err)
                goto fail;

        if (need_balance && !IS_NOQUOTA(inode) &&
                        has_not_enough_free_secs(sbi, 0, 0)) {
                unlock_page(page);
                f2fs_balance_fs(sbi, true);
                lock_page(page);
                if (page->mapping != mapping) {
                        /* The page got truncated from under us */
                        f2fs_put_page(page, 1);
                        goto repeat;
                }
        }

        f2fs_wait_on_page_writeback(page, DATA, false, true);

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

        if (!(pos & (PAGE_SIZE - 1)) && (pos + len) >= i_size_read(inode) &&
            !f2fs_verity_in_progress(inode)) {
                zero_user_segment(page, len, PAGE_SIZE);
                return 0;
        }

        if (blkaddr == NEW_ADDR) {
                zero_user_segment(page, 0, PAGE_SIZE);
                SetPageUptodate(page);
        } else {
                if (!f2fs_is_valid_blkaddr(sbi, blkaddr,
                                DATA_GENERIC_ENHANCE_READ)) {
                        err = -EFSCORRUPTED;
                        goto fail;
                }
                err = f2fs_submit_page_read(inode, page, blkaddr);
                if (err)
                        goto fail;

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

fail:
        f2fs_put_page(page, 1);
        f2fs_write_failed(mapping, pos + len);
        if (drop_atomic)
                f2fs_drop_inmem_pages_all(sbi, false);
        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);

        /*
         * This should be come from len == PAGE_SIZE, and we expect copied
         * should be PAGE_SIZE. Otherwise, we treat it with zero copied and
         * let generic_perform_write() try to copy data again through copied=0.
         */
        if (!PageUptodate(page)) {
                if (unlikely(copied != len))
                        copied = 0;
                else
                        SetPageUptodate(page);
        }
        if (!copied)
                goto unlock_out;

        set_page_dirty(page);

        if (pos + copied > i_size_read(inode) &&
            !f2fs_verity_in_progress(inode))
                f2fs_i_size_write(inode, pos + copied);
unlock_out:
        f2fs_put_page(page, 1);
        f2fs_update_time(F2FS_I_SB(inode), REQ_TIME);
        return copied;
}

static int check_direct_IO(struct inode *inode, struct iov_iter *iter,
                           loff_t offset)
{
        unsigned i_blkbits = READ_ONCE(inode->i_blkbits);
        unsigned blkbits = i_blkbits;
        unsigned blocksize_mask = (1 << blkbits) - 1;
        unsigned long align = offset | iov_iter_alignment(iter);
        struct block_device *bdev = inode->i_sb->s_bdev;

        if (align & blocksize_mask) {
                if (bdev)
                        blkbits = blksize_bits(bdev_logical_block_size(bdev));
                blocksize_mask = (1 << blkbits) - 1;
                if (align & blocksize_mask)
                        return -EINVAL;
                return 1;
        }
        return 0;
}

static void f2fs_dio_end_io(struct bio *bio)
{
        struct f2fs_private_dio *dio = bio->bi_private;

        dec_page_count(F2FS_I_SB(dio->inode),
                        dio->write ? F2FS_DIO_WRITE : F2FS_DIO_READ);

        bio->bi_private = dio->orig_private;
        bio->bi_end_io = dio->orig_end_io;

        kvfree(dio);

        bio_endio(bio);
}

static void f2fs_dio_submit_bio(struct bio *bio, struct inode *inode,
                                                        loff_t file_offset)
{
        struct f2fs_private_dio *dio;
        bool write = (bio_op(bio) == REQ_OP_WRITE);

        dio = f2fs_kzalloc(F2FS_I_SB(inode),
                        sizeof(struct f2fs_private_dio), GFP_NOFS);
        if (!dio)
                goto out;

        dio->inode = inode;
        dio->orig_end_io = bio->bi_end_io;
        dio->orig_private = bio->bi_private;
        dio->write = write;

        bio->bi_end_io = f2fs_dio_end_io;
        bio->bi_private = dio;

        inc_page_count(F2FS_I_SB(inode),
                        write ? F2FS_DIO_WRITE : F2FS_DIO_READ);

        submit_bio(bio);
        return;
out:
        bio->bi_status = BLK_STS_IOERR;
        bio_endio(bio);
}

static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
{
        struct address_space *mapping = iocb->ki_filp->f_mapping;
        struct inode *inode = mapping->host;
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct f2fs_inode_info *fi = F2FS_I(inode);
        size_t count = iov_iter_count(iter);
        loff_t offset = iocb->ki_pos;
        int rw = iov_iter_rw(iter);
        int err;
        enum rw_hint hint = iocb->ki_hint;
        int whint_mode = F2FS_OPTION(sbi).whint_mode;
        bool do_opu;

        err = check_direct_IO(inode, iter, offset);
        if (err)
                return err < 0 ? err : 0;

        if (f2fs_force_buffered_io(inode, iocb, iter))
                return 0;

        do_opu = allow_outplace_dio(inode, iocb, iter);

        trace_f2fs_direct_IO_enter(inode, offset, count, rw);

        if (rw == WRITE && whint_mode == WHINT_MODE_OFF)
                iocb->ki_hint = WRITE_LIFE_NOT_SET;

        if (iocb->ki_flags & IOCB_NOWAIT) {
                if (!down_read_trylock(&fi->i_gc_rwsem[rw])) {
                        iocb->ki_hint = hint;
                        err = -EAGAIN;
                        goto out;
                }
                if (do_opu && !down_read_trylock(&fi->i_gc_rwsem[READ])) {
                        up_read(&fi->i_gc_rwsem[rw]);
                        iocb->ki_hint = hint;
                        err = -EAGAIN;
                        goto out;
                }
        } else {
                down_read(&fi->i_gc_rwsem[rw]);
                if (do_opu)
                        down_read(&fi->i_gc_rwsem[READ]);
        }

        err = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,
                        iter, rw == WRITE ? get_data_block_dio_write :
                        get_data_block_dio, NULL, f2fs_dio_submit_bio,
                        DIO_LOCKING | DIO_SKIP_HOLES);

        if (do_opu)
                up_read(&fi->i_gc_rwsem[READ]);

        up_read(&fi->i_gc_rwsem[rw]);

        if (rw == WRITE) {
                if (whint_mode == WHINT_MODE_OFF)
                        iocb->ki_hint = hint;
                if (err > 0) {
                        f2fs_update_iostat(F2FS_I_SB(inode), APP_DIRECT_IO,
                                                                        err);
                        if (!do_opu)
                                set_inode_flag(inode, FI_UPDATE_WRITE);
                } else if (err < 0) {
                        f2fs_write_failed(mapping, offset + count);
                }
        }

out:
        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_SIZE || length != PAGE_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);
                        f2fs_remove_dirty_inode(inode);
                }
        }

        clear_cold_data(page);

        if (IS_ATOMIC_WRITTEN_PAGE(page))
                return f2fs_drop_inmem_page(inode, page);

        f2fs_clear_page_private(page);
}

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

        /* This is atomic written page, keep Private */
        if (IS_ATOMIC_WRITTEN_PAGE(page))
                return 0;

        clear_cold_data(page);
        f2fs_clear_page_private(page);
        return 1;
}

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

        trace_f2fs_set_page_dirty(page, DATA);

        if (!PageUptodate(page))
                SetPageUptodate(page);
        if (PageSwapCache(page))
                return __set_page_dirty_nobuffers(page);

        if (f2fs_is_atomic_file(inode) && !f2fs_is_commit_atomic_write(inode)) {
                if (!IS_ATOMIC_WRITTEN_PAGE(page)) {
                        f2fs_register_inmem_page(inode, page);
                        return 1;
                }
                /*
                 * Previously, this page has been registered, we just
                 * return here.
                 */
                return 0;
        }

        if (!PageDirty(page)) {
                __set_page_dirty_nobuffers(page);
                f2fs_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;

        if (f2fs_has_inline_data(inode))
                return 0;

        /* make sure allocating whole blocks */
        if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
                filemap_write_and_wait(mapping);

        return generic_block_bmap(mapping, block, get_data_block_bmap);
}

#ifdef CONFIG_MIGRATION
#include <linux/migrate.h>

int f2fs_migrate_page(struct address_space *mapping,
                struct page *newpage, struct page *page, enum migrate_mode mode)
{
        int rc, extra_count;
        struct f2fs_inode_info *fi = F2FS_I(mapping->host);
        bool atomic_written = IS_ATOMIC_WRITTEN_PAGE(page);

        BUG_ON(PageWriteback(page));

        /* migrating an atomic written page is safe with the inmem_lock hold */