mm: fix kerneldoc on mem_cgroup_replace_page

[mirror_ubuntu-bionic-kernel.git] / fs / f2fs / dir.c

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

static unsigned long dir_blocks(struct inode *inode)
{
        return ((unsigned long long) (i_size_read(inode) + PAGE_CACHE_SIZE - 1))
                                                        >> PAGE_CACHE_SHIFT;
}

static unsigned int dir_buckets(unsigned int level, int dir_level)
{
        if (level + dir_level < MAX_DIR_HASH_DEPTH / 2)
                return 1 << (level + dir_level);
        else
                return MAX_DIR_BUCKETS;
}

static unsigned int bucket_blocks(unsigned int level)
{
        if (level < MAX_DIR_HASH_DEPTH / 2)
                return 2;
        else
                return 4;
}

unsigned char f2fs_filetype_table[F2FS_FT_MAX] = {
        [F2FS_FT_UNKNOWN]       = DT_UNKNOWN,
        [F2FS_FT_REG_FILE]      = DT_REG,
        [F2FS_FT_DIR]           = DT_DIR,
        [F2FS_FT_CHRDEV]        = DT_CHR,
        [F2FS_FT_BLKDEV]        = DT_BLK,
        [F2FS_FT_FIFO]          = DT_FIFO,
        [F2FS_FT_SOCK]          = DT_SOCK,
        [F2FS_FT_SYMLINK]       = DT_LNK,
};

#define S_SHIFT 12
static unsigned char f2fs_type_by_mode[S_IFMT >> S_SHIFT] = {
        [S_IFREG >> S_SHIFT]    = F2FS_FT_REG_FILE,
        [S_IFDIR >> S_SHIFT]    = F2FS_FT_DIR,
        [S_IFCHR >> S_SHIFT]    = F2FS_FT_CHRDEV,
        [S_IFBLK >> S_SHIFT]    = F2FS_FT_BLKDEV,
        [S_IFIFO >> S_SHIFT]    = F2FS_FT_FIFO,
        [S_IFSOCK >> S_SHIFT]   = F2FS_FT_SOCK,
        [S_IFLNK >> S_SHIFT]    = F2FS_FT_SYMLINK,
};

void set_de_type(struct f2fs_dir_entry *de, umode_t mode)
{
        de->file_type = f2fs_type_by_mode[(mode & S_IFMT) >> S_SHIFT];
}

static unsigned long dir_block_index(unsigned int level,
                                int dir_level, unsigned int idx)
{
        unsigned long i;
        unsigned long bidx = 0;

        for (i = 0; i < level; i++)
                bidx += dir_buckets(i, dir_level) * bucket_blocks(i);
        bidx += idx * bucket_blocks(level);
        return bidx;
}

static struct f2fs_dir_entry *find_in_block(struct page *dentry_page,
                                struct f2fs_filename *fname,
                                f2fs_hash_t namehash,
                                int *max_slots,
                                struct page **res_page)
{
        struct f2fs_dentry_block *dentry_blk;
        struct f2fs_dir_entry *de;
        struct f2fs_dentry_ptr d;

        dentry_blk = (struct f2fs_dentry_block *)kmap(dentry_page);

        make_dentry_ptr(NULL, &d, (void *)dentry_blk, 1);
        de = find_target_dentry(fname, namehash, max_slots, &d);
        if (de)
                *res_page = dentry_page;
        else
                kunmap(dentry_page);

        /*
         * For the most part, it should be a bug when name_len is zero.
         * We stop here for figuring out where the bugs has occurred.
         */
        f2fs_bug_on(F2FS_P_SB(dentry_page), d.max < 0);
        return de;
}

struct f2fs_dir_entry *find_target_dentry(struct f2fs_filename *fname,
                        f2fs_hash_t namehash, int *max_slots,
                        struct f2fs_dentry_ptr *d)
{
        struct f2fs_dir_entry *de;
        unsigned long bit_pos = 0;
        int max_len = 0;
        struct f2fs_str de_name = FSTR_INIT(NULL, 0);
        struct f2fs_str *name = &fname->disk_name;

        if (max_slots)
                *max_slots = 0;
        while (bit_pos < d->max) {
                if (!test_bit_le(bit_pos, d->bitmap)) {
                        bit_pos++;
                        max_len++;
                        continue;
                }

                de = &d->dentry[bit_pos];

                /* encrypted case */
                de_name.name = d->filename[bit_pos];
                de_name.len = le16_to_cpu(de->name_len);

                /* show encrypted name */
                if (fname->hash) {
                        if (de->hash_code == fname->hash)
                                goto found;
                } else if (de_name.len == name->len &&
                        de->hash_code == namehash &&
                        !memcmp(de_name.name, name->name, name->len))
                        goto found;

                if (max_slots && max_len > *max_slots)
                        *max_slots = max_len;
                max_len = 0;

                /* remain bug on condition */
                if (unlikely(!de->name_len))
                        d->max = -1;

                bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
        }

        de = NULL;
found:
        if (max_slots && max_len > *max_slots)
                *max_slots = max_len;
        return de;
}

static struct f2fs_dir_entry *find_in_level(struct inode *dir,
                                        unsigned int level,
                                        struct f2fs_filename *fname,
                                        struct page **res_page)
{
        struct qstr name = FSTR_TO_QSTR(&fname->disk_name);
        int s = GET_DENTRY_SLOTS(name.len);
        unsigned int nbucket, nblock;
        unsigned int bidx, end_block;
        struct page *dentry_page;
        struct f2fs_dir_entry *de = NULL;
        bool room = false;
        int max_slots;
        f2fs_hash_t namehash;

        namehash = f2fs_dentry_hash(&name);

        f2fs_bug_on(F2FS_I_SB(dir), level > MAX_DIR_HASH_DEPTH);

        nbucket = dir_buckets(level, F2FS_I(dir)->i_dir_level);
        nblock = bucket_blocks(level);

        bidx = dir_block_index(level, F2FS_I(dir)->i_dir_level,
                                        le32_to_cpu(namehash) % nbucket);
        end_block = bidx + nblock;

        for (; bidx < end_block; bidx++) {
                /* no need to allocate new dentry pages to all the indices */
                dentry_page = find_data_page(dir, bidx);
                if (IS_ERR(dentry_page)) {
                        room = true;
                        continue;
                }

                de = find_in_block(dentry_page, fname, namehash, &max_slots,
                                                                res_page);
                if (de)
                        break;

                if (max_slots >= s)
                        room = true;
                f2fs_put_page(dentry_page, 0);
        }

        if (!de && room && F2FS_I(dir)->chash != namehash) {
                F2FS_I(dir)->chash = namehash;
                F2FS_I(dir)->clevel = level;
        }

        return de;
}

/*
 * Find an entry in the specified directory with the wanted name.
 * It returns the page where the entry was found (as a parameter - res_page),
 * and the entry itself. Page is returned mapped and unlocked.
 * Entry is guaranteed to be valid.
 */
struct f2fs_dir_entry *f2fs_find_entry(struct inode *dir,
                        struct qstr *child, struct page **res_page)
{
        unsigned long npages = dir_blocks(dir);
        struct f2fs_dir_entry *de = NULL;
        unsigned int max_depth;
        unsigned int level;
        struct f2fs_filename fname;
        int err;

        *res_page = NULL;

        err = f2fs_fname_setup_filename(dir, child, 1, &fname);
        if (err)
                return NULL;

        if (f2fs_has_inline_dentry(dir)) {
                de = find_in_inline_dir(dir, &fname, res_page);
                goto out;
        }

        if (npages == 0)
                goto out;

        max_depth = F2FS_I(dir)->i_current_depth;

        for (level = 0; level < max_depth; level++) {
                de = find_in_level(dir, level, &fname, res_page);
                if (de)
                        break;
        }
out:
        f2fs_fname_free_filename(&fname);
        return de;
}

struct f2fs_dir_entry *f2fs_parent_dir(struct inode *dir, struct page **p)
{
        struct page *page;
        struct f2fs_dir_entry *de;
        struct f2fs_dentry_block *dentry_blk;

        if (f2fs_has_inline_dentry(dir))
                return f2fs_parent_inline_dir(dir, p);

        page = get_lock_data_page(dir, 0, false);
        if (IS_ERR(page))
                return NULL;

        dentry_blk = kmap(page);
        de = &dentry_blk->dentry[1];
        *p = page;
        unlock_page(page);
        return de;
}

ino_t f2fs_inode_by_name(struct inode *dir, struct qstr *qstr)
{
        ino_t res = 0;
        struct f2fs_dir_entry *de;
        struct page *page;

        de = f2fs_find_entry(dir, qstr, &page);
        if (de) {
                res = le32_to_cpu(de->ino);
                f2fs_dentry_kunmap(dir, page);
                f2fs_put_page(page, 0);
        }

        return res;
}

void f2fs_set_link(struct inode *dir, struct f2fs_dir_entry *de,
                struct page *page, struct inode *inode)
{
        enum page_type type = f2fs_has_inline_dentry(dir) ? NODE : DATA;
        lock_page(page);
        f2fs_wait_on_page_writeback(page, type);
        de->ino = cpu_to_le32(inode->i_ino);
        set_de_type(de, inode->i_mode);
        f2fs_dentry_kunmap(dir, page);
        set_page_dirty(page);
        dir->i_mtime = dir->i_ctime = CURRENT_TIME;
        mark_inode_dirty(dir);

        f2fs_put_page(page, 1);
}

static void init_dent_inode(const struct qstr *name, struct page *ipage)
{
        struct f2fs_inode *ri;

        f2fs_wait_on_page_writeback(ipage, NODE);

        /* copy name info. to this inode page */
        ri = F2FS_INODE(ipage);
        ri->i_namelen = cpu_to_le32(name->len);
        memcpy(ri->i_name, name->name, name->len);
        set_page_dirty(ipage);
}

int update_dent_inode(struct inode *inode, struct inode *to,
                                        const struct qstr *name)
{
        struct page *page;

        if (file_enc_name(to))
                return 0;

        page = get_node_page(F2FS_I_SB(inode), inode->i_ino);
        if (IS_ERR(page))
                return PTR_ERR(page);

        init_dent_inode(name, page);
        f2fs_put_page(page, 1);

        return 0;
}

void do_make_empty_dir(struct inode *inode, struct inode *parent,
                                        struct f2fs_dentry_ptr *d)
{
        struct f2fs_dir_entry *de;

        de = &d->dentry[0];
        de->name_len = cpu_to_le16(1);
        de->hash_code = 0;
        de->ino = cpu_to_le32(inode->i_ino);
        memcpy(d->filename[0], ".", 1);
        set_de_type(de, inode->i_mode);

        de = &d->dentry[1];
        de->hash_code = 0;
        de->name_len = cpu_to_le16(2);
        de->ino = cpu_to_le32(parent->i_ino);
        memcpy(d->filename[1], "..", 2);
        set_de_type(de, parent->i_mode);

        test_and_set_bit_le(0, (void *)d->bitmap);
        test_and_set_bit_le(1, (void *)d->bitmap);
}

static int make_empty_dir(struct inode *inode,
                struct inode *parent, struct page *page)
{
        struct page *dentry_page;
        struct f2fs_dentry_block *dentry_blk;
        struct f2fs_dentry_ptr d;

        if (f2fs_has_inline_dentry(inode))
                return make_empty_inline_dir(inode, parent, page);

        dentry_page = get_new_data_page(inode, page, 0, true);
        if (IS_ERR(dentry_page))
                return PTR_ERR(dentry_page);

        dentry_blk = kmap_atomic(dentry_page);

        make_dentry_ptr(NULL, &d, (void *)dentry_blk, 1);
        do_make_empty_dir(inode, parent, &d);

        kunmap_atomic(dentry_blk);

        set_page_dirty(dentry_page);
        f2fs_put_page(dentry_page, 1);
        return 0;
}

struct page *init_inode_metadata(struct inode *inode, struct inode *dir,
                        const struct qstr *name, struct page *dpage)
{
        struct page *page;
        int err;

        if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
                page = new_inode_page(inode);
                if (IS_ERR(page))
                        return page;

                if (S_ISDIR(inode->i_mode)) {
                        err = make_empty_dir(inode, dir, page);
                        if (err)
                                goto error;
                }

                err = f2fs_init_acl(inode, dir, page, dpage);
                if (err)
                        goto put_error;

                err = f2fs_init_security(inode, dir, name, page);
                if (err)
                        goto put_error;

                if (f2fs_encrypted_inode(dir) && f2fs_may_encrypt(inode)) {
                        err = f2fs_inherit_context(dir, inode, page);
                        if (err)
                                goto put_error;
                }
        } else {
                page = get_node_page(F2FS_I_SB(dir), inode->i_ino);
                if (IS_ERR(page))
                        return page;

                set_cold_node(inode, page);
        }

        if (name)
                init_dent_inode(name, page);

        /*
         * This file should be checkpointed during fsync.
         * We lost i_pino from now on.
         */
        if (is_inode_flag_set(F2FS_I(inode), FI_INC_LINK)) {
                file_lost_pino(inode);
                /*
                 * If link the tmpfile to alias through linkat path,
                 * we should remove this inode from orphan list.
                 */
                if (inode->i_nlink == 0)
                        remove_orphan_inode(F2FS_I_SB(dir), inode->i_ino);
                inc_nlink(inode);
        }
        return page;

put_error:
        f2fs_put_page(page, 1);
error:
        /* once the failed inode becomes a bad inode, i_mode is S_IFREG */
        truncate_inode_pages(&inode->i_data, 0);
        truncate_blocks(inode, 0, false);
        remove_dirty_dir_inode(inode);
        remove_inode_page(inode);
        return ERR_PTR(err);
}

void update_parent_metadata(struct inode *dir, struct inode *inode,
                                                unsigned int current_depth)
{
        if (inode && is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
                if (S_ISDIR(inode->i_mode)) {
                        inc_nlink(dir);
                        set_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
                }
                clear_inode_flag(F2FS_I(inode), FI_NEW_INODE);
        }
        dir->i_mtime = dir->i_ctime = CURRENT_TIME;
        mark_inode_dirty(dir);

        if (F2FS_I(dir)->i_current_depth != current_depth) {
                F2FS_I(dir)->i_current_depth = current_depth;
                set_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
        }

        if (inode && is_inode_flag_set(F2FS_I(inode), FI_INC_LINK))
                clear_inode_flag(F2FS_I(inode), FI_INC_LINK);
}

int room_for_filename(const void *bitmap, int slots, int max_slots)
{
        int bit_start = 0;
        int zero_start, zero_end;
next:
        zero_start = find_next_zero_bit_le(bitmap, max_slots, bit_start);
        if (zero_start >= max_slots)
                return max_slots;

        zero_end = find_next_bit_le(bitmap, max_slots, zero_start);
        if (zero_end - zero_start >= slots)
                return zero_start;

        bit_start = zero_end + 1;

        if (zero_end + 1 >= max_slots)
                return max_slots;
        goto next;
}

void f2fs_update_dentry(nid_t ino, umode_t mode, struct f2fs_dentry_ptr *d,
                                const struct qstr *name, f2fs_hash_t name_hash,
                                unsigned int bit_pos)
{
        struct f2fs_dir_entry *de;
        int slots = GET_DENTRY_SLOTS(name->len);
        int i;

        de = &d->dentry[bit_pos];
        de->hash_code = name_hash;
        de->name_len = cpu_to_le16(name->len);
        memcpy(d->filename[bit_pos], name->name, name->len);
        de->ino = cpu_to_le32(ino);
        set_de_type(de, mode);
        for (i = 0; i < slots; i++)
                test_and_set_bit_le(bit_pos + i, (void *)d->bitmap);
}

/*
 * Caller should grab and release a rwsem by calling f2fs_lock_op() and
 * f2fs_unlock_op().
 */
int __f2fs_add_link(struct inode *dir, const struct qstr *name,
                                struct inode *inode, nid_t ino, umode_t mode)
{
        unsigned int bit_pos;
        unsigned int level;
        unsigned int current_depth;
        unsigned long bidx, block;
        f2fs_hash_t dentry_hash;
        unsigned int nbucket, nblock;
        struct page *dentry_page = NULL;
        struct f2fs_dentry_block *dentry_blk = NULL;
        struct f2fs_dentry_ptr d;
        struct page *page = NULL;
        struct f2fs_filename fname;
        struct qstr new_name;
        int slots, err;

        err = f2fs_fname_setup_filename(dir, name, 0, &fname);
        if (err)
                return err;

        new_name.name = fname_name(&fname);
        new_name.len = fname_len(&fname);

        if (f2fs_has_inline_dentry(dir)) {
                err = f2fs_add_inline_entry(dir, &new_name, inode, ino, mode);
                if (!err || err != -EAGAIN)
                        goto out;
                else
                        err = 0;
        }

        level = 0;
        slots = GET_DENTRY_SLOTS(new_name.len);
        dentry_hash = f2fs_dentry_hash(&new_name);

        current_depth = F2FS_I(dir)->i_current_depth;
        if (F2FS_I(dir)->chash == dentry_hash) {
                level = F2FS_I(dir)->clevel;
                F2FS_I(dir)->chash = 0;
        }

start:
        if (unlikely(current_depth == MAX_DIR_HASH_DEPTH)) {
                err = -ENOSPC;
                goto out;
        }

        /* Increase the depth, if required */
        if (level == current_depth)
                ++current_depth;

        nbucket = dir_buckets(level, F2FS_I(dir)->i_dir_level);
        nblock = bucket_blocks(level);

        bidx = dir_block_index(level, F2FS_I(dir)->i_dir_level,
                                (le32_to_cpu(dentry_hash) % nbucket));

        for (block = bidx; block <= (bidx + nblock - 1); block++) {
                dentry_page = get_new_data_page(dir, NULL, block, true);
                if (IS_ERR(dentry_page)) {
                        err = PTR_ERR(dentry_page);
                        goto out;
                }

                dentry_blk = kmap(dentry_page);
                bit_pos = room_for_filename(&dentry_blk->dentry_bitmap,
                                                slots, NR_DENTRY_IN_BLOCK);
                if (bit_pos < NR_DENTRY_IN_BLOCK)
                        goto add_dentry;

                kunmap(dentry_page);
                f2fs_put_page(dentry_page, 1);
        }

        /* Move to next level to find the empty slot for new dentry */
        ++level;
        goto start;
add_dentry:
        f2fs_wait_on_page_writeback(dentry_page, DATA);

        if (inode) {
                down_write(&F2FS_I(inode)->i_sem);
                page = init_inode_metadata(inode, dir, &new_name, NULL);
                if (IS_ERR(page)) {
                        err = PTR_ERR(page);
                        goto fail;
                }
                if (f2fs_encrypted_inode(dir))
                        file_set_enc_name(inode);
        }

        make_dentry_ptr(NULL, &d, (void *)dentry_blk, 1);
        f2fs_update_dentry(ino, mode, &d, &new_name, dentry_hash, bit_pos);

        set_page_dirty(dentry_page);

        if (inode) {
                /* we don't need to mark_inode_dirty now */
                F2FS_I(inode)->i_pino = dir->i_ino;
                update_inode(inode, page);
                f2fs_put_page(page, 1);
        }

        update_parent_metadata(dir, inode, current_depth);
fail:
        if (inode)
                up_write(&F2FS_I(inode)->i_sem);

        if (is_inode_flag_set(F2FS_I(dir), FI_UPDATE_DIR)) {
                update_inode_page(dir);
                clear_inode_flag(F2FS_I(dir), FI_UPDATE_DIR);
        }
        kunmap(dentry_page);
        f2fs_put_page(dentry_page, 1);
out:
        f2fs_fname_free_filename(&fname);
        return err;
}

int f2fs_do_tmpfile(struct inode *inode, struct inode *dir)
{
        struct page *page;
        int err = 0;

        down_write(&F2FS_I(inode)->i_sem);
        page = init_inode_metadata(inode, dir, NULL, NULL);
        if (IS_ERR(page)) {
                err = PTR_ERR(page);
                goto fail;
        }
        /* we don't need to mark_inode_dirty now */
        update_inode(inode, page);
        f2fs_put_page(page, 1);

        clear_inode_flag(F2FS_I(inode), FI_NEW_INODE);
fail:
        up_write(&F2FS_I(inode)->i_sem);
        return err;
}

void f2fs_drop_nlink(struct inode *dir, struct inode *inode, struct page *page)
{
        struct f2fs_sb_info *sbi = F2FS_I_SB(dir);

        down_write(&F2FS_I(inode)->i_sem);

        if (S_ISDIR(inode->i_mode)) {
                drop_nlink(dir);
                if (page)
                        update_inode(dir, page);
                else
                        update_inode_page(dir);
        }
        inode->i_ctime = CURRENT_TIME;

        drop_nlink(inode);
        if (S_ISDIR(inode->i_mode)) {
                drop_nlink(inode);
                i_size_write(inode, 0);
        }
        up_write(&F2FS_I(inode)->i_sem);
        update_inode_page(inode);

        if (inode->i_nlink == 0)
                add_orphan_inode(sbi, inode->i_ino);
        else
                release_orphan_inode(sbi);
}

/*
 * It only removes the dentry from the dentry page, corresponding name
 * entry in name page does not need to be touched during deletion.
 */
void f2fs_delete_entry(struct f2fs_dir_entry *dentry, struct page *page,
                                        struct inode *dir, struct inode *inode)
{
        struct  f2fs_dentry_block *dentry_blk;
        unsigned int bit_pos;
        int slots = GET_DENTRY_SLOTS(le16_to_cpu(dentry->name_len));
        int i;

        if (f2fs_has_inline_dentry(dir))
                return f2fs_delete_inline_entry(dentry, page, dir, inode);

        lock_page(page);
        f2fs_wait_on_page_writeback(page, DATA);

        dentry_blk = page_address(page);
        bit_pos = dentry - dentry_blk->dentry;
        for (i = 0; i < slots; i++)
                clear_bit_le(bit_pos + i, &dentry_blk->dentry_bitmap);

        /* Let's check and deallocate this dentry page */
        bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
                        NR_DENTRY_IN_BLOCK,
                        0);
        kunmap(page); /* kunmap - pair of f2fs_find_entry */
        set_page_dirty(page);

        dir->i_ctime = dir->i_mtime = CURRENT_TIME;

        if (inode)
                f2fs_drop_nlink(dir, inode, NULL);

        if (bit_pos == NR_DENTRY_IN_BLOCK &&
                        !truncate_hole(dir, page->index, page->index + 1)) {
                clear_page_dirty_for_io(page);
                ClearPagePrivate(page);
                ClearPageUptodate(page);
                inode_dec_dirty_pages(dir);
        }
        f2fs_put_page(page, 1);
}

bool f2fs_empty_dir(struct inode *dir)
{
        unsigned long bidx;
        struct page *dentry_page;
        unsigned int bit_pos;
        struct f2fs_dentry_block *dentry_blk;
        unsigned long nblock = dir_blocks(dir);

        if (f2fs_has_inline_dentry(dir))
                return f2fs_empty_inline_dir(dir);

        for (bidx = 0; bidx < nblock; bidx++) {
                dentry_page = get_lock_data_page(dir, bidx, false);
                if (IS_ERR(dentry_page)) {
                        if (PTR_ERR(dentry_page) == -ENOENT)
                                continue;
                        else
                                return false;
                }

                dentry_blk = kmap_atomic(dentry_page);
                if (bidx == 0)
                        bit_pos = 2;
                else
                        bit_pos = 0;
                bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
                                                NR_DENTRY_IN_BLOCK,
                                                bit_pos);
                kunmap_atomic(dentry_blk);

                f2fs_put_page(dentry_page, 1);

                if (bit_pos < NR_DENTRY_IN_BLOCK)
                        return false;
        }
        return true;
}

bool f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d,
                                unsigned int start_pos, struct f2fs_str *fstr)
{
        unsigned char d_type = DT_UNKNOWN;
        unsigned int bit_pos;
        struct f2fs_dir_entry *de = NULL;
        struct f2fs_str de_name = FSTR_INIT(NULL, 0);

        bit_pos = ((unsigned long)ctx->pos % d->max);

        while (bit_pos < d->max) {
                bit_pos = find_next_bit_le(d->bitmap, d->max, bit_pos);
                if (bit_pos >= d->max)
                        break;

                de = &d->dentry[bit_pos];
                if (de->file_type < F2FS_FT_MAX)
                        d_type = f2fs_filetype_table[de->file_type];
                else
                        d_type = DT_UNKNOWN;

                de_name.name = d->filename[bit_pos];
                de_name.len = le16_to_cpu(de->name_len);

                if (f2fs_encrypted_inode(d->inode)) {
                        int save_len = fstr->len;
                        int ret;

                        de_name.name = kmalloc(de_name.len, GFP_NOFS);
                        if (!de_name.name)
                                return false;

                        memcpy(de_name.name, d->filename[bit_pos], de_name.len);

                        ret = f2fs_fname_disk_to_usr(d->inode, &de->hash_code,
                                                        &de_name, fstr);
                        kfree(de_name.name);
                        if (ret < 0)
                                return true;

                        de_name = *fstr;
                        fstr->len = save_len;
                }

                if (!dir_emit(ctx, de_name.name, de_name.len,
                                        le32_to_cpu(de->ino), d_type))
                        return true;

                bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
                ctx->pos = start_pos + bit_pos;
        }
        return false;
}

static int f2fs_readdir(struct file *file, struct dir_context *ctx)
{
        struct inode *inode = file_inode(file);
        unsigned long npages = dir_blocks(inode);
        struct f2fs_dentry_block *dentry_blk = NULL;
        struct page *dentry_page = NULL;
        struct file_ra_state *ra = &file->f_ra;
        unsigned int n = ((unsigned long)ctx->pos / NR_DENTRY_IN_BLOCK);
        struct f2fs_dentry_ptr d;
        struct f2fs_str fstr = FSTR_INIT(NULL, 0);
        int err = 0;

        if (f2fs_encrypted_inode(inode)) {
                err = f2fs_get_encryption_info(inode);
                if (err)
                        return err;

                err = f2fs_fname_crypto_alloc_buffer(inode, F2FS_NAME_LEN,
                                                                &fstr);
                if (err < 0)
                        return err;
        }

        if (f2fs_has_inline_dentry(inode)) {
                err = f2fs_read_inline_dir(file, ctx, &fstr);
                goto out;
        }

        /* readahead for multi pages of dir */
        if (npages - n > 1 && !ra_has_index(ra, n))
                page_cache_sync_readahead(inode->i_mapping, ra, file, n,
                                min(npages - n, (pgoff_t)MAX_DIR_RA_PAGES));

        for (; n < npages; n++) {
                dentry_page = get_lock_data_page(inode, n, false);
                if (IS_ERR(dentry_page))
                        continue;

                dentry_blk = kmap(dentry_page);

                make_dentry_ptr(inode, &d, (void *)dentry_blk, 1);

                if (f2fs_fill_dentries(ctx, &d, n * NR_DENTRY_IN_BLOCK, &fstr))
                        goto stop;

                ctx->pos = (n + 1) * NR_DENTRY_IN_BLOCK;
                kunmap(dentry_page);
                f2fs_put_page(dentry_page, 1);
                dentry_page = NULL;
        }
stop:
        if (dentry_page && !IS_ERR(dentry_page)) {
                kunmap(dentry_page);
                f2fs_put_page(dentry_page, 1);
        }
out:
        f2fs_fname_crypto_free_buffer(&fstr);
        return err;
}

const struct file_operations f2fs_dir_operations = {
        .llseek         = generic_file_llseek,
        .read           = generic_read_dir,
        .iterate        = f2fs_readdir,
        .fsync          = f2fs_sync_file,
        .unlocked_ioctl = f2fs_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = f2fs_compat_ioctl,
#endif
};