// SPDX-License-Identifier: GPL-2.0
/*
 *
 * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
 *
 */

#include <linux/buffer_head.h>
#include <linux/fs.h>
#include <linux/mpage.h>
#include <linux/namei.h>
#include <linux/nls.h>
#include <linux/uio.h>
#include <linux/writeback.h>
#include <linux/iomap.h>

#include "debug.h"
#include "ntfs.h"
#include "ntfs_fs.h"

/*
 * ntfs_read_mft - Read record and parse MFT.
 */
static struct inode *ntfs_read_mft(struct inode *inode,
                                   const struct cpu_str *name,
                                   const struct MFT_REF *ref)
{
        int err = 0;
        struct ntfs_inode *ni = ntfs_i(inode);
        struct super_block *sb = inode->i_sb;
        struct ntfs_sb_info *sbi = sb->s_fs_info;
        mode_t mode = 0;
        struct ATTR_STD_INFO5 *std5 = NULL;
        struct ATTR_LIST_ENTRY *le;
        struct ATTRIB *attr;
        bool is_match = false;
        bool is_root = false;
        bool is_dir;
        unsigned long ino = inode->i_ino;
        u32 rp_fa = 0, asize, t32;
        u16 roff, rsize, names = 0, links = 0;
        const struct ATTR_FILE_NAME *fname = NULL;
        const struct INDEX_ROOT *root = NULL;
        struct REPARSE_DATA_BUFFER rp; // 0x18 bytes
        u64 t64;
        struct MFT_REC *rec;
        struct runs_tree *run;
        struct timespec64 ts;

        inode->i_op = NULL;
        /* Setup 'uid' and 'gid' */
        inode->i_uid = sbi->options->fs_uid;
        inode->i_gid = sbi->options->fs_gid;

        err = mi_init(&ni->mi, sbi, ino);
        if (err)
                goto out;

        if (!sbi->mft.ni && ino == MFT_REC_MFT && !sb->s_root) {
                t64 = sbi->mft.lbo >> sbi->cluster_bits;
                t32 = bytes_to_cluster(sbi, MFT_REC_VOL * sbi->record_size);
                sbi->mft.ni = ni;
                init_rwsem(&ni->file.run_lock);

                if (!run_add_entry(&ni->file.run, 0, t64, t32, true)) {
                        err = -ENOMEM;
                        goto out;
                }
        }

        err = mi_read(&ni->mi, ino == MFT_REC_MFT);

        if (err)
                goto out;

        rec = ni->mi.mrec;

        if (sbi->flags & NTFS_FLAGS_LOG_REPLAYING) {
                ;
        } else if (ref->seq != rec->seq) {
                err = -EINVAL;
                ntfs_err(sb, "MFT: r=%lx, expect seq=%x instead of %x!", ino,
                         le16_to_cpu(ref->seq), le16_to_cpu(rec->seq));
                goto out;
        } else if (!is_rec_inuse(rec)) {
                err = -ESTALE;
                ntfs_err(sb, "Inode r=%x is not in use!", (u32)ino);
                goto out;
        }

        if (le32_to_cpu(rec->total) != sbi->record_size) {
                /* Bad inode? */
                err = -EINVAL;
                goto out;
        }

        if (!is_rec_base(rec)) {
                err = -EINVAL;
                goto out;
        }

        /* Record should contain $I30 root. */
        is_dir = rec->flags & RECORD_FLAG_DIR;

        /* MFT_REC_MFT is not a dir */
        if (is_dir && ino == MFT_REC_MFT) {
                err = -EINVAL;
                goto out;
        }

        inode->i_generation = le16_to_cpu(rec->seq);

        /* Enumerate all struct Attributes MFT. */
        le = NULL;
        attr = NULL;

        /*
         * To reduce tab pressure use goto instead of
         * while( (attr = ni_enum_attr_ex(ni, attr, &le, NULL) ))
         */
next_attr:
        run = NULL;
        err = -EINVAL;
        attr = ni_enum_attr_ex(ni, attr, &le, NULL);
        if (!attr)
                goto end_enum;

        if (le && le->vcn) {
                /* This is non primary attribute segment. Ignore if not MFT. */
                if (ino != MFT_REC_MFT || attr->type != ATTR_DATA)
                        goto next_attr;

                run = &ni->file.run;
                asize = le32_to_cpu(attr->size);
                goto attr_unpack_run;
        }

        roff = attr->non_res ? 0 : le16_to_cpu(attr->res.data_off);
        rsize = attr->non_res ? 0 : le32_to_cpu(attr->res.data_size);
        asize = le32_to_cpu(attr->size);

        /*
         * Really this check was done in 'ni_enum_attr_ex' -> ... 'mi_enum_attr'.
         * There not critical to check this case again
         */
        if (attr->name_len &&
            sizeof(short) * attr->name_len + le16_to_cpu(attr->name_off) >
                    asize)
                goto out;

        if (attr->non_res) {
                t64 = le64_to_cpu(attr->nres.alloc_size);
                if (le64_to_cpu(attr->nres.data_size) > t64 ||
                    le64_to_cpu(attr->nres.valid_size) > t64)
                        goto out;
        }

        switch (attr->type) {
        case ATTR_STD:
                if (attr->non_res ||
                    asize < sizeof(struct ATTR_STD_INFO) + roff ||
                    rsize < sizeof(struct ATTR_STD_INFO))
                        goto out;

                if (std5)
                        goto next_attr;

                std5 = Add2Ptr(attr, roff);

                nt2kernel(std5->cr_time, &ni->i_crtime);
                nt2kernel(std5->a_time, &ts);
                inode_set_atime_to_ts(inode, ts);
                nt2kernel(std5->c_time, &ts);
                inode_set_ctime_to_ts(inode, ts);
                nt2kernel(std5->m_time, &ts);
                inode_set_mtime_to_ts(inode, ts);

                ni->std_fa = std5->fa;

                if (asize >= sizeof(struct ATTR_STD_INFO5) + roff &&
                    rsize >= sizeof(struct ATTR_STD_INFO5))
                        ni->std_security_id = std5->security_id;
                goto next_attr;

        case ATTR_LIST:
                if (attr->name_len || le || ino == MFT_REC_LOG)
                        goto out;

                err = ntfs_load_attr_list(ni, attr);
                if (err)
                        goto out;

                le = NULL;
                attr = NULL;
                goto next_attr;

        case ATTR_NAME:
                if (attr->non_res || asize < SIZEOF_ATTRIBUTE_FILENAME + roff ||
                    rsize < SIZEOF_ATTRIBUTE_FILENAME)
                        goto out;

                names += 1;
                fname = Add2Ptr(attr, roff);
                if (fname->type == FILE_NAME_DOS)
                        goto next_attr;

                links += 1;
                if (name && name->len == fname->name_len &&
                    !ntfs_cmp_names_cpu(name, (struct le_str *)&fname->name_len,
                                        NULL, false))
                        is_match = true;

                goto next_attr;

        case ATTR_DATA:
                if (is_dir) {
                        /* Ignore data attribute in dir record. */
                        goto next_attr;
                }

                if (ino == MFT_REC_BADCLUST && !attr->non_res)
                        goto next_attr;

                if (attr->name_len &&
                    ((ino != MFT_REC_BADCLUST || !attr->non_res ||
                      attr->name_len != ARRAY_SIZE(BAD_NAME) ||
                      memcmp(attr_name(attr), BAD_NAME, sizeof(BAD_NAME))) &&
                     (ino != MFT_REC_SECURE || !attr->non_res ||
                      attr->name_len != ARRAY_SIZE(SDS_NAME) ||
                      memcmp(attr_name(attr), SDS_NAME, sizeof(SDS_NAME))))) {
                        /* File contains stream attribute. Ignore it. */
                        goto next_attr;
                }

                if (is_attr_sparsed(attr))
                        ni->std_fa |= FILE_ATTRIBUTE_SPARSE_FILE;
                else
                        ni->std_fa &= ~FILE_ATTRIBUTE_SPARSE_FILE;

                if (is_attr_compressed(attr))
                        ni->std_fa |= FILE_ATTRIBUTE_COMPRESSED;
                else
                        ni->std_fa &= ~FILE_ATTRIBUTE_COMPRESSED;

                if (is_attr_encrypted(attr))
                        ni->std_fa |= FILE_ATTRIBUTE_ENCRYPTED;
                else
                        ni->std_fa &= ~FILE_ATTRIBUTE_ENCRYPTED;

                if (!attr->non_res) {
                        ni->i_valid = inode->i_size = rsize;
                        inode_set_bytes(inode, rsize);
                }

                mode = S_IFREG | (0777 & sbi->options->fs_fmask_inv);

                if (!attr->non_res) {
                        ni->ni_flags |= NI_FLAG_RESIDENT;
                        goto next_attr;
                }

                inode_set_bytes(inode, attr_ondisk_size(attr));

                ni->i_valid = le64_to_cpu(attr->nres.valid_size);
                inode->i_size = le64_to_cpu(attr->nres.data_size);
                if (!attr->nres.alloc_size)
                        goto next_attr;

                run = ino == MFT_REC_BITMAP ? &sbi->used.bitmap.run :
                                              &ni->file.run;
                break;

        case ATTR_ROOT:
                if (attr->non_res)
                        goto out;

                root = Add2Ptr(attr, roff);

                if (attr->name_len != ARRAY_SIZE(I30_NAME) ||
                    memcmp(attr_name(attr), I30_NAME, sizeof(I30_NAME)))
                        goto next_attr;

                if (root->type != ATTR_NAME ||
                    root->rule != NTFS_COLLATION_TYPE_FILENAME)
                        goto out;

                if (!is_dir)
                        goto next_attr;

                is_root = true;
                ni->ni_flags |= NI_FLAG_DIR;

                err = indx_init(&ni->dir, sbi, attr, INDEX_MUTEX_I30);
                if (err)
                        goto out;

                mode = sb->s_root ?
                               (S_IFDIR | (0777 & sbi->options->fs_dmask_inv)) :
                               (S_IFDIR | 0777);
                goto next_attr;

        case ATTR_ALLOC:
                if (!is_root || attr->name_len != ARRAY_SIZE(I30_NAME) ||
                    memcmp(attr_name(attr), I30_NAME, sizeof(I30_NAME)))
                        goto next_attr;

                inode->i_size = le64_to_cpu(attr->nres.data_size);
                ni->i_valid = le64_to_cpu(attr->nres.valid_size);
                inode_set_bytes(inode, le64_to_cpu(attr->nres.alloc_size));

                run = &ni->dir.alloc_run;
                break;

        case ATTR_BITMAP:
                if (ino == MFT_REC_MFT) {
                        if (!attr->non_res)
                                goto out;
#ifndef CONFIG_NTFS3_64BIT_CLUSTER
                        /* 0x20000000 = 2^32 / 8 */
                        if (le64_to_cpu(attr->nres.alloc_size) >= 0x20000000)
                                goto out;
#endif
                        run = &sbi->mft.bitmap.run;
                        break;
                } else if (is_dir && attr->name_len == ARRAY_SIZE(I30_NAME) &&
                           !memcmp(attr_name(attr), I30_NAME,
                                   sizeof(I30_NAME)) &&
                           attr->non_res) {
                        run = &ni->dir.bitmap_run;
                        break;
                }
                goto next_attr;

        case ATTR_REPARSE:
                if (attr->name_len)
                        goto next_attr;

                rp_fa = ni_parse_reparse(ni, attr, &rp);
                switch (rp_fa) {
                case REPARSE_LINK:
                        /*
                         * Normal symlink.
                         * Assume one unicode symbol == one utf8.
                         */
                        inode->i_size = le16_to_cpu(rp.SymbolicLinkReparseBuffer
                                                            .PrintNameLength) /
                                        sizeof(u16);
                        ni->i_valid = inode->i_size;
                        /* Clear directory bit. */
                        if (ni->ni_flags & NI_FLAG_DIR) {
                                indx_clear(&ni->dir);
                                memset(&ni->dir, 0, sizeof(ni->dir));
                                ni->ni_flags &= ~NI_FLAG_DIR;
                        } else {
                                run_close(&ni->file.run);
                        }
                        mode = S_IFLNK | 0777;
                        is_dir = false;
                        if (attr->non_res) {
                                run = &ni->file.run;
                                goto attr_unpack_run; // Double break.
                        }
                        break;

                case REPARSE_COMPRESSED:
                        break;

                case REPARSE_DEDUPLICATED:
                        break;
                }
                goto next_attr;

        case ATTR_EA_INFO:
                if (!attr->name_len &&
                    resident_data_ex(attr, sizeof(struct EA_INFO))) {
                        ni->ni_flags |= NI_FLAG_EA;
                        /*
                         * ntfs_get_wsl_perm updates inode->i_uid, inode->i_gid, inode->i_mode
                         */
                        inode->i_mode = mode;
                        ntfs_get_wsl_perm(inode);
                        mode = inode->i_mode;
                }
                goto next_attr;

        default:
                goto next_attr;
        }

attr_unpack_run:
        roff = le16_to_cpu(attr->nres.run_off);

        if (roff > asize) {
                err = -EINVAL;
                goto out;
        }

        t64 = le64_to_cpu(attr->nres.svcn);

        err = run_unpack_ex(run, sbi, ino, t64, le64_to_cpu(attr->nres.evcn),
                            t64, Add2Ptr(attr, roff), asize - roff);
        if (err < 0)
                goto out;
        err = 0;
        goto next_attr;

end_enum:

        if (!std5)
                goto out;

        if (is_bad_inode(inode))
                goto out;

        if (!is_match && name) {
                err = -ENOENT;
                goto out;
        }

        if (std5->fa & FILE_ATTRIBUTE_READONLY)
                mode &= ~0222;

        if (!names) {
                err = -EINVAL;
                goto out;
        }

        if (names != le16_to_cpu(rec->hard_links)) {
                /* Correct minor error on the fly. Do not mark inode as dirty. */
                ntfs_inode_warn(inode, "Correct links count -> %u.", names);
                rec->hard_links = cpu_to_le16(names);
                ni->mi.dirty = true;
        }

        set_nlink(inode, links);

        if (S_ISDIR(mode)) {
                ni->std_fa |= FILE_ATTRIBUTE_DIRECTORY;

                /*
                 * Dot and dot-dot should be included in count but was not
                 * included in enumeration.
                 * Usually a hard links to directories are disabled.
                 */
                inode->i_op = &ntfs_dir_inode_operations;
                inode->i_fop = unlikely(is_legacy_ntfs(sb)) ?
                                       &ntfs_legacy_dir_operations :
                                       &ntfs_dir_operations;
                ni->i_valid = 0;
        } else if (S_ISLNK(mode)) {
                ni->std_fa &= ~FILE_ATTRIBUTE_DIRECTORY;
                inode->i_op = &ntfs_link_inode_operations;
                inode->i_fop = NULL;
                inode_nohighmem(inode);
        } else if (S_ISREG(mode)) {
                ni->std_fa &= ~FILE_ATTRIBUTE_DIRECTORY;
                inode->i_op = &ntfs_file_inode_operations;
                inode->i_fop = unlikely(is_legacy_ntfs(sb)) ?
                                       &ntfs_legacy_file_operations :
                                       &ntfs_file_operations;
                inode->i_mapping->a_ops = is_compressed(ni) ? &ntfs_aops_cmpr :
                                                              &ntfs_aops;
                if (ino != MFT_REC_MFT)
                        init_rwsem(&ni->file.run_lock);
        } else if (S_ISCHR(mode) || S_ISBLK(mode) || S_ISFIFO(mode) ||
                   S_ISSOCK(mode)) {
                inode->i_op = &ntfs_special_inode_operations;
                init_special_inode(inode, mode, inode->i_rdev);
        } else if (fname && fname->home.low == cpu_to_le32(MFT_REC_EXTEND) &&
                   fname->home.seq == cpu_to_le16(MFT_REC_EXTEND)) {
                /* Records in $Extend are not a files or general directories. */
                inode->i_op = &ntfs_file_inode_operations;
                mode = S_IFREG;
                init_rwsem(&ni->file.run_lock);
        } else {
                err = -EINVAL;
                goto out;
        }

        if ((sbi->options->sys_immutable &&
             (std5->fa & FILE_ATTRIBUTE_SYSTEM)) &&
            !S_ISFIFO(mode) && !S_ISSOCK(mode) && !S_ISLNK(mode)) {
                inode->i_flags |= S_IMMUTABLE;
        } else {
                inode->i_flags &= ~S_IMMUTABLE;
        }

        inode->i_mode = mode;
        if (!(ni->ni_flags & NI_FLAG_EA)) {
                /* If no xattr then no security (stored in xattr). */
                inode->i_flags |= S_NOSEC;
        }

        if (ino == MFT_REC_MFT && !sb->s_root)
                sbi->mft.ni = NULL;

        unlock_new_inode(inode);

        return inode;

out:
        if (ino == MFT_REC_MFT && !sb->s_root)
                sbi->mft.ni = NULL;

        iget_failed(inode);
        return ERR_PTR(err);
}

/*
 * ntfs_test_inode
 *
 * Return: 1 if match.
 */
static int ntfs_test_inode(struct inode *inode, void *data)
{
        struct MFT_REF *ref = data;

        return ino_get(ref) == inode->i_ino;
}

static int ntfs_set_inode(struct inode *inode, void *data)
{
        const struct MFT_REF *ref = data;

        inode->i_ino = ino_get(ref);
        return 0;
}

struct inode *ntfs_iget5(struct super_block *sb, const struct MFT_REF *ref,
                         const struct cpu_str *name)
{
        struct inode *inode;

        inode = iget5_locked(sb, ino_get(ref), ntfs_test_inode, ntfs_set_inode,
                             (void *)ref);
        if (unlikely(!inode))
                return ERR_PTR(-ENOMEM);

        /* If this is a freshly allocated inode, need to read it now. */
        if (inode_state_read_once(inode) & I_NEW)
                inode = ntfs_read_mft(inode, name, ref);
        else if (ref->seq != ntfs_i(inode)->mi.mrec->seq) {
                /*
                 * Sequence number is not expected.
                 * Looks like inode was reused but caller uses the old reference
                 */
                iput(inode);
                inode = ERR_PTR(-ESTALE);
        }

        if (IS_ERR(inode))
                ntfs_set_state(sb->s_fs_info, NTFS_DIRTY_ERROR);

        return inode;
}

static sector_t ntfs_bmap(struct address_space *mapping, sector_t block)
{
        struct inode *inode = mapping->host;
        struct ntfs_inode *ni = ntfs_i(inode);

        /*
         * We can get here for an inline file via the FIBMAP ioctl
         */
        if (is_resident(ni))
                return 0;

        if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
            !run_is_empty(&ni->file.run_da)) {
                /*
                 * With delalloc data we want to sync the file so
                 * that we can make sure we allocate blocks for file and data
                 * is in place for the user to see it
                 */
                ni_allocate_da_blocks(ni);
        }

        return iomap_bmap(mapping, block, &ntfs_iomap_ops);
}

static void ntfs_iomap_read_end_io(struct bio *bio)
{
        int error = blk_status_to_errno(bio->bi_status);
        struct folio_iter fi;

        bio_for_each_folio_all(fi, bio) {
                struct folio *folio = fi.folio;
                struct inode *inode = folio->mapping->host;
                struct ntfs_inode *ni = ntfs_i(inode);
                u64 valid = ni->i_valid;
                u32 f_size = folio_size(folio);
                loff_t f_pos = folio_pos(folio);


                if (valid < f_pos + f_size) {
                        u32 z_from = valid <= f_pos ?
                                             0 :
                                             offset_in_folio(folio, valid);
                        /* The only thing ntfs_iomap_read_end_io used for. */
                        folio_zero_segment(folio, z_from, f_size);
                }

                iomap_finish_folio_read(folio, fi.offset, fi.length, error);
        }
        bio_put(bio);
}

/*
 * Copied from iomap/bio.c.
 */
static int ntfs_iomap_bio_read_folio_range(const struct iomap_iter *iter,
                                           struct iomap_read_folio_ctx *ctx,
                                           size_t plen)
{
        struct folio *folio = ctx->cur_folio;
        const struct iomap *iomap = &iter->iomap;
        loff_t pos = iter->pos;
        size_t poff = offset_in_folio(folio, pos);
        loff_t length = iomap_length(iter);
        sector_t sector;
        struct bio *bio = ctx->read_ctx;

        sector = iomap_sector(iomap, pos);
        if (!bio || bio_end_sector(bio) != sector ||
            !bio_add_folio(bio, folio, plen, poff)) {
                gfp_t gfp = mapping_gfp_constraint(folio->mapping, GFP_KERNEL);
                gfp_t orig_gfp = gfp;
                unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE);

                if (bio)
                        submit_bio(bio);

                if (ctx->rac) /* same as readahead_gfp_mask */
                        gfp |= __GFP_NORETRY | __GFP_NOWARN;
                bio = bio_alloc(iomap->bdev, bio_max_segs(nr_vecs), REQ_OP_READ,
                                gfp);
                /*
                 * If the bio_alloc fails, try it again for a single page to
                 * avoid having to deal with partial page reads.  This emulates
                 * what do_mpage_read_folio does.
                 */
                if (!bio)
                        bio = bio_alloc(iomap->bdev, 1, REQ_OP_READ, orig_gfp);
                if (ctx->rac)
                        bio->bi_opf |= REQ_RAHEAD;
                bio->bi_iter.bi_sector = sector;
                bio->bi_end_io = ntfs_iomap_read_end_io;
                bio_add_folio_nofail(bio, folio, plen, poff);
                ctx->read_ctx = bio;
        }
        return 0;
}

static void ntfs_iomap_bio_submit_read(struct iomap_read_folio_ctx *ctx)
{
        struct bio *bio = ctx->read_ctx;

        if (bio)
                submit_bio(bio);
}

static const struct iomap_read_ops ntfs_iomap_bio_read_ops = {
        .read_folio_range = ntfs_iomap_bio_read_folio_range,
        .submit_read = ntfs_iomap_bio_submit_read,
};

static int ntfs_read_folio(struct file *file, struct folio *folio)
{
        int err;
        struct address_space *mapping = folio->mapping;
        struct inode *inode = mapping->host;
        struct ntfs_inode *ni = ntfs_i(inode);
        loff_t vbo = folio_pos(folio);
        struct iomap_read_folio_ctx ctx = {
                .cur_folio = folio,
                .ops = &ntfs_iomap_bio_read_ops,
        };

        if (unlikely(is_bad_ni(ni))) {
                folio_unlock(folio);
                return -EIO;
        }

        if (ni->i_valid <= vbo) {
                folio_zero_range(folio, 0, folio_size(folio));
                folio_mark_uptodate(folio);
                folio_unlock(folio);
                return 0;
        }

        if (is_compressed(ni)) {
                /* ni_lock is taken inside ni_read_folio_cmpr after page locks */
                err = ni_read_folio_cmpr(ni, folio);
                return err;
        }

        iomap_read_folio(&ntfs_iomap_ops, &ctx, NULL);
        return 0;
}

static void ntfs_readahead(struct readahead_control *rac)
{
        struct address_space *mapping = rac->mapping;
        struct inode *inode = mapping->host;
        struct ntfs_inode *ni = ntfs_i(inode);
        struct iomap_read_folio_ctx ctx = {
                .ops = &ntfs_iomap_bio_read_ops,
                .rac = rac,
        };

        if (is_resident(ni)) {
                /* No readahead for resident. */
                return;
        }

        if (is_compressed(ni)) {
                /* No readahead for compressed. */
                return;
        }

        iomap_readahead(&ntfs_iomap_ops, &ctx, NULL);
}

int ntfs_set_size(struct inode *inode, u64 new_size)
{
        struct super_block *sb = inode->i_sb;
        struct ntfs_sb_info *sbi = sb->s_fs_info;
        struct ntfs_inode *ni = ntfs_i(inode);
        int err;

        /* Check for maximum file size. */
        if (is_sparsed(ni) || is_compressed(ni)) {
                if (new_size > sbi->maxbytes_sparse) {
                        return -EFBIG;
                }
        } else if (new_size > sbi->maxbytes) {
                return -EFBIG;
        }

        ni_lock(ni);
        down_write(&ni->file.run_lock);

        err = attr_set_size(ni, ATTR_DATA, NULL, 0, &ni->file.run, new_size,
                            &ni->i_valid, true);

        if (!err) {
                i_size_write(inode, new_size);
                mark_inode_dirty(inode);
        }

        up_write(&ni->file.run_lock);
        ni_unlock(ni);

        return err;
}

/*
 * Special value to detect ntfs_writeback_range call
 */
#define WB_NO_DA (struct iomap *)1
/*
 * Function to get mapping vbo -> lbo.
 * used with:
 * - iomap_zero_range
 * - iomap_truncate_page
 * - iomap_dio_rw
 * - iomap_file_buffered_write
 * - iomap_bmap
 * - iomap_fiemap
 * - iomap_bio_read_folio
 * - iomap_bio_readahead
 */
static int ntfs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
                            unsigned int flags, struct iomap *iomap,
                            struct iomap *srcmap)
{
        struct ntfs_inode *ni = ntfs_i(inode);
        struct ntfs_sb_info *sbi = ni->mi.sbi;
        u8 cluster_bits = sbi->cluster_bits;
        CLST vcn = offset >> cluster_bits;
        u32 off = offset & sbi->cluster_mask;
        bool rw = flags & IOMAP_WRITE;
        loff_t endbyte = offset + length;
        void *res = NULL;
        int err;
        CLST lcn, clen, clen_max = 1;
        bool new_clst = false;
        bool no_da;
        bool zero = false;
        if (unlikely(ntfs3_forced_shutdown(sbi->sb)))
                return -EIO;

        if (flags & IOMAP_REPORT) {
                if (offset > ntfs_get_maxbytes(ni)) {
                        /* called from fiemap/bmap. */
                        return -EINVAL;
                }

                if (offset >= inode->i_size) {
                        /* special code for report. */
                        return -ENOENT;
                }
        }

        if (IOMAP_ZERO == flags && (endbyte & sbi->cluster_mask)) {
                rw = true;
        } else if (rw) {
                clen_max = bytes_to_cluster(sbi, endbyte) - vcn;
        }

        /* 
         * Force to allocate clusters if directIO(write) or writeback_range.
         * NOTE: attr_data_get_block allocates clusters only for sparse file.
         * Normal file allocates clusters in attr_set_size.
        */
        no_da = flags == (IOMAP_DIRECT | IOMAP_WRITE) || srcmap == WB_NO_DA;

        err = attr_data_get_block(ni, vcn, clen_max, &lcn, &clen,
                                  rw ? &new_clst : NULL, zero, &res, no_da);

        if (err) {
                return err;
        }

        if (lcn == EOF_LCN) {
                /* request out of file. */
                if (flags & IOMAP_REPORT) {
                        /* special code for report. */
                        return -ENOENT;
                }

                if (rw) {
                        /* should never be here. */
                        return -EINVAL;
                }
                lcn = SPARSE_LCN;
        }

        iomap->flags = new_clst ? IOMAP_F_NEW : 0;

        if (lcn == RESIDENT_LCN) {
                if (offset >= clen) {
                        kfree(res);
                        if (flags & IOMAP_REPORT) {
                                /* special code for report. */
                                return -ENOENT;
                        }
                        return -EFAULT;
                }

                iomap->private = iomap->inline_data = res;
                iomap->type = IOMAP_INLINE;
                iomap->offset = 0;
                iomap->length = clen; /* resident size in bytes. */
                return 0;
        }

        if (!clen) {
                /* broken file? */
                return -EINVAL;
        }

        iomap->bdev = inode->i_sb->s_bdev;
        iomap->offset = offset;
        iomap->length = ((loff_t)clen << cluster_bits) - off;

        if (lcn == COMPRESSED_LCN) {
                /* should never be here. */
                return -EOPNOTSUPP;
        }

        if (lcn == DELALLOC_LCN) {
                iomap->type = IOMAP_DELALLOC;
                iomap->addr = IOMAP_NULL_ADDR;
        } else {

                /* Translate clusters into bytes. */
                iomap->addr = ((loff_t)lcn << cluster_bits) + off;
                if (length && iomap->length > length)
                        iomap->length = length;
                else
                        endbyte = offset + iomap->length;

                if (lcn == SPARSE_LCN) {
                        iomap->addr = IOMAP_NULL_ADDR;
                        iomap->type = IOMAP_HOLE;
                        //                      if (IOMAP_ZERO == flags && !off) {
                        //                              iomap->length = (endbyte - offset) &
                        //                                              sbi->cluster_mask_inv;
                        //                      }
                } else if (endbyte <= ni->i_valid) {
                        iomap->type = IOMAP_MAPPED;
                } else if (offset < ni->i_valid) {
                        iomap->type = IOMAP_MAPPED;
                        if (flags & IOMAP_REPORT)
                                iomap->length = ni->i_valid - offset;
                } else if (rw || (flags & IOMAP_ZERO)) {
                        iomap->type = IOMAP_MAPPED;
                } else {
                        iomap->type = IOMAP_UNWRITTEN;
                }
        }

        if ((flags & IOMAP_ZERO) &&
            (iomap->type == IOMAP_MAPPED || iomap->type == IOMAP_DELALLOC)) {
                /* Avoid too large requests. */
                u32 tail;
                u32 off_a = offset & (PAGE_SIZE - 1);
                if (off_a)
                        tail = PAGE_SIZE - off_a;
                else
                        tail = PAGE_SIZE;

                if (iomap->length > tail)
                        iomap->length = tail;
        }

        return 0;
}

static int ntfs_iomap_end(struct inode *inode, loff_t pos, loff_t length,
                          ssize_t written, unsigned int flags,
                          struct iomap *iomap)
{
        int err = 0;
        struct ntfs_inode *ni = ntfs_i(inode);
        loff_t endbyte = pos + written;

        if ((flags & IOMAP_WRITE) || (flags & IOMAP_ZERO)) {
                if (iomap->type == IOMAP_INLINE) {
                        u32 data_size;
                        struct ATTRIB *attr;
                        struct mft_inode *mi;

                        attr = ni_find_attr(ni, NULL, NULL, ATTR_DATA, NULL, 0,
                                            NULL, &mi);
                        if (!attr || attr->non_res) {
                                err = -EINVAL;
                                goto out;
                        }

                        data_size = le32_to_cpu(attr->res.data_size);
                        if (!(pos < data_size && endbyte <= data_size)) {
                                err = -EINVAL;
                                goto out;
                        }

                        /* Update resident data. */
                        memcpy(resident_data(attr) + pos,
                               iomap_inline_data(iomap, pos), written);
                        mi->dirty = true;
                        ni->i_valid = data_size;
                } else if (ni->i_valid < endbyte) {
                        ni->i_valid = endbyte;
                        mark_inode_dirty(inode);
                }
        }

        if ((flags & IOMAP_ZERO) &&
            (iomap->type == IOMAP_MAPPED || iomap->type == IOMAP_DELALLOC)) {
                /* Pair for code in ntfs_iomap_begin. */
                balance_dirty_pages_ratelimited(inode->i_mapping);
                cond_resched();
        }

out:
        if (iomap->type == IOMAP_INLINE) {
                kfree(iomap->private);
                iomap->private = NULL;
        }

        return err;
}

/*
 * write_begin + put_folio + write_end.
 * iomap_zero_range
 * iomap_truncate_page
 * iomap_file_buffered_write
 */
static void ntfs_iomap_put_folio(struct inode *inode, loff_t pos,
                                 unsigned int len, struct folio *folio)
{
        struct ntfs_inode *ni = ntfs_i(inode);
        loff_t end = pos + len;
        u32 f_size = folio_size(folio);
        loff_t f_pos = folio_pos(folio);
        loff_t f_end = f_pos + f_size;

        if (ni->i_valid <= end && end < f_end) {
                /* zero range [end - f_end). */
                /* The only thing ntfs_iomap_put_folio used for. */
                folio_zero_segment(folio, offset_in_folio(folio, end), f_size);
        }
        folio_unlock(folio);
        folio_put(folio);
}

/*
 * iomap_writeback_ops::writeback_range
 */
static ssize_t ntfs_writeback_range(struct iomap_writepage_ctx *wpc,
                                    struct folio *folio, u64 offset,
                                    unsigned int len, u64 end_pos)
{
        struct iomap *iomap = &wpc->iomap;
        /* Check iomap position. */
        if (iomap->offset + iomap->length <= offset || offset < iomap->offset) {
                int err;
                struct inode *inode = wpc->inode;
                struct ntfs_inode *ni = ntfs_i(inode);
                struct ntfs_sb_info *sbi = ntfs_sb(inode->i_sb);
                loff_t i_size_up = ntfs_up_cluster(sbi, inode->i_size);
                loff_t len_max = i_size_up - offset;

                err = ni->file.run_da.count ? ni_allocate_da_blocks(ni) : 0;

                if (!err) {
                        /* Use local special value 'WB_NO_DA' to disable delalloc. */
                        err = ntfs_iomap_begin(inode, offset, len_max,
                                               IOMAP_WRITE, iomap, WB_NO_DA);
                }

                if (err) {
                        ntfs_set_state(sbi, NTFS_DIRTY_DIRTY);
                        return err;
                }
        }

        return iomap_add_to_ioend(wpc, folio, offset, end_pos, len);
}


static const struct iomap_writeback_ops ntfs_writeback_ops = {
        .writeback_range = ntfs_writeback_range,
        .writeback_submit = iomap_ioend_writeback_submit,
};

static int ntfs_resident_writepage(struct folio *folio,
                                   struct writeback_control *wbc)
{
        struct address_space *mapping = folio->mapping;
        struct inode *inode = mapping->host;
        struct ntfs_inode *ni = ntfs_i(inode);
        int ret;

        /* Avoid any operation if inode is bad. */
        if (unlikely(is_bad_ni(ni)))
                return -EINVAL;

        if (unlikely(ntfs3_forced_shutdown(inode->i_sb)))
                return -EIO;

        ni_lock(ni);
        ret = attr_data_write_resident(ni, folio);
        ni_unlock(ni);

        if (ret != E_NTFS_NONRESIDENT)
                folio_unlock(folio);
        mapping_set_error(mapping, ret);
        return ret;
}

static int ntfs_writepages(struct address_space *mapping,
                           struct writeback_control *wbc)
{
        int err;
        struct inode *inode = mapping->host;
        struct ntfs_inode *ni = ntfs_i(inode);
        struct iomap_writepage_ctx wpc = {
                .inode = mapping->host,
                .wbc = wbc,
                .ops = &ntfs_writeback_ops,
        };

        /* Avoid any operation if inode is bad. */
        if (unlikely(is_bad_ni(ni)))
                return -EINVAL;

        if (unlikely(ntfs3_forced_shutdown(inode->i_sb)))
                return -EIO;

        if (is_resident(ni)) {
                struct folio *folio = NULL;

                while ((folio = writeback_iter(mapping, wbc, folio, &err)))
                        err = ntfs_resident_writepage(folio, wbc);

                return err;
        }

        return iomap_writepages(&wpc);
}

int ntfs3_write_inode(struct inode *inode, struct writeback_control *wbc)
{
        return _ni_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
}

int ntfs_sync_inode(struct inode *inode)
{
        return _ni_write_inode(inode, 1);
}

/*
 * Helper function to read file.
 * Used to read $AttrDef and $UpCase
 */
int inode_read_data(struct inode *inode, void *data, size_t bytes)
{
        pgoff_t idx;
        struct address_space *mapping = inode->i_mapping;

        for (idx = 0; bytes; idx++) {
                size_t op = bytes > PAGE_SIZE ? PAGE_SIZE : bytes;
                struct page *page = read_mapping_page(mapping, idx, NULL);
                void *kaddr;

                if (IS_ERR(page))
                        return PTR_ERR(page);

                kaddr = kmap_atomic(page);
                memcpy(data, kaddr, op);
                kunmap_atomic(kaddr);

                put_page(page);

                bytes -= op;
                data = Add2Ptr(data, PAGE_SIZE);
        }
        return 0;
}

/*
 * ntfs_reparse_bytes
 *
 * Number of bytes for REPARSE_DATA_BUFFER(IO_REPARSE_TAG_SYMLINK)
 * for unicode string of @uni_len length.
 */
static inline u32 ntfs_reparse_bytes(u32 uni_len, bool is_absolute)
{
        /* Header + unicode string + decorated unicode string. */
        return sizeof(short) * (2 * uni_len + (is_absolute ? 4 : 0)) +
               offsetof(struct REPARSE_DATA_BUFFER,
                        SymbolicLinkReparseBuffer.PathBuffer);
}

static struct REPARSE_DATA_BUFFER *
ntfs_create_reparse_buffer(struct ntfs_sb_info *sbi, const char *symname,
                           u32 size, u16 *nsize)
{
        int i, err;
        struct REPARSE_DATA_BUFFER *rp;
        __le16 *rp_name;
        typeof(rp->SymbolicLinkReparseBuffer) *rs;
        bool is_absolute;

        is_absolute = symname[0] && symname[1] == ':';

        rp = kzalloc(ntfs_reparse_bytes(2 * size + 2, is_absolute), GFP_NOFS);
        if (!rp)
                return ERR_PTR(-ENOMEM);

        rs = &rp->SymbolicLinkReparseBuffer;
        rp_name = rs->PathBuffer;

        /* Convert link name to UTF-16. */
        err = ntfs_nls_to_utf16(sbi, symname, size,
                                (struct cpu_str *)(rp_name - 1), 2 * size,
                                UTF16_LITTLE_ENDIAN);
        if (err < 0)
                goto out;

        /* err = the length of unicode name of symlink. */
        *nsize = ntfs_reparse_bytes(err, is_absolute);

        if (*nsize > sbi->reparse.max_size) {
                err = -EFBIG;
                goto out;
        }

        /* Translate Linux '/' into Windows '\'. */
        for (i = 0; i < err; i++) {
                if (rp_name[i] == cpu_to_le16('/'))
                        rp_name[i] = cpu_to_le16('\\');
        }

        rp->ReparseTag = IO_REPARSE_TAG_SYMLINK;
        rp->ReparseDataLength =
                cpu_to_le16(*nsize - offsetof(struct REPARSE_DATA_BUFFER,
                                              SymbolicLinkReparseBuffer));

        /* PrintName + SubstituteName. */
        rs->SubstituteNameOffset = cpu_to_le16(sizeof(short) * err);
        rs->SubstituteNameLength =
                cpu_to_le16(sizeof(short) * err + (is_absolute ? 8 : 0));
        rs->PrintNameLength = rs->SubstituteNameOffset;

        /*
         * TODO: Use relative path if possible to allow Windows to
         * parse this path.
         * 0-absolute path, 1- relative path (SYMLINK_FLAG_RELATIVE).
         */
        rs->Flags = cpu_to_le32(is_absolute ? 0 : SYMLINK_FLAG_RELATIVE);

        memmove(rp_name + err + (is_absolute ? 4 : 0), rp_name,
                sizeof(short) * err);

        if (is_absolute) {
                /* Decorate SubstituteName. */
                rp_name += err;
                rp_name[0] = cpu_to_le16('\\');
                rp_name[1] = cpu_to_le16('?');
                rp_name[2] = cpu_to_le16('?');
                rp_name[3] = cpu_to_le16('\\');
        }

        return rp;
out:
        kfree(rp);
        return ERR_PTR(err);
}

/*
 * ntfs_create_inode
 *
 * Helper function for:
 * - ntfs_create
 * - ntfs_mknod
 * - ntfs_symlink
 * - ntfs_mkdir
 * - ntfs_atomic_open
 *
 * NOTE: if fnd != NULL (ntfs_atomic_open) then @dir is locked
 */
int ntfs_create_inode(struct mnt_idmap *idmap, struct inode *dir,
                      struct dentry *dentry, const struct cpu_str *uni,
                      umode_t mode, dev_t dev, const char *symname, u32 size,
                      struct ntfs_fnd *fnd)
{
        int err;
        struct super_block *sb = dir->i_sb;
        struct ntfs_sb_info *sbi = sb->s_fs_info;
        const struct qstr *name = &dentry->d_name;
        CLST ino = 0;
        struct ntfs_inode *dir_ni = ntfs_i(dir);
        struct ntfs_inode *ni = NULL;
        struct inode *inode = NULL;
        struct ATTRIB *attr;
        struct ATTR_STD_INFO5 *std5;
        struct ATTR_FILE_NAME *fname;
        struct MFT_REC *rec;
        u32 asize, dsize, sd_size;
        enum FILE_ATTRIBUTE fa;
        __le32 security_id = SECURITY_ID_INVALID;
        CLST vcn;
        const void *sd;
        u16 t16, nsize = 0, aid = 0;
        struct INDEX_ROOT *root, *dir_root;
        struct NTFS_DE *e, *new_de = NULL;
        struct REPARSE_DATA_BUFFER *rp = NULL;
        bool rp_inserted = false;

        /* New file will be resident or non resident. */
        const bool new_file_resident = 1;

        if (!fnd)
                ni_lock_dir(dir_ni);

        dir_root = indx_get_root(&dir_ni->dir, dir_ni, NULL, NULL);
        if (!dir_root) {
                err = -EINVAL;
                goto out1;
        }

        if (S_ISDIR(mode)) {
                /* Use parent's directory attributes. */
                fa = dir_ni->std_fa | FILE_ATTRIBUTE_DIRECTORY |
                     FILE_ATTRIBUTE_ARCHIVE;
                /*
                 * By default child directory inherits parent attributes.
                 * Root directory is hidden + system.
                 * Make an exception for children in root.
                 */
                if (dir->i_ino == MFT_REC_ROOT)
                        fa &= ~(FILE_ATTRIBUTE_HIDDEN | FILE_ATTRIBUTE_SYSTEM);
        } else if (S_ISLNK(mode)) {
                /* It is good idea that link should be the same type (file/dir) as target */
                fa = FILE_ATTRIBUTE_REPARSE_POINT;

                /*
                 * Linux: there are dir/file/symlink and so on.
                 * NTFS: symlinks are "dir + reparse" or "file + reparse"
                 * It is good idea to create:
                 * dir + reparse if 'symname' points to directory
                 * or
                 * file + reparse if 'symname' points to file
                 * Unfortunately kern_path hangs if symname contains 'dir'.
                 */

                /*
                 *      struct path path;
                 *
                 *      if (!kern_path(symname, LOOKUP_FOLLOW, &path)){
                 *              struct inode *target = d_inode(path.dentry);
                 *
                 *              if (S_ISDIR(target->i_mode))
                 *                      fa |= FILE_ATTRIBUTE_DIRECTORY;
                 *              // if ( target->i_sb == sb ){
                 *              //      use relative path?
                 *              // }
                 *              path_put(&path);
                 *      }
                 */
        } else if (S_ISREG(mode)) {
                if (sbi->options->sparse) {
                        /* Sparsed regular file, cause option 'sparse'. */
                        fa = FILE_ATTRIBUTE_SPARSE_FILE |
                             FILE_ATTRIBUTE_ARCHIVE;
                } else if (dir_ni->std_fa & FILE_ATTRIBUTE_COMPRESSED) {
                        /* Compressed regular file, if parent is compressed. */
                        fa = FILE_ATTRIBUTE_COMPRESSED | FILE_ATTRIBUTE_ARCHIVE;
                } else {
                        /* Regular file, default attributes. */
                        fa = FILE_ATTRIBUTE_ARCHIVE;
                }
        } else {
                fa = FILE_ATTRIBUTE_ARCHIVE;
        }

        /* If option "hide_dot_files" then set hidden attribute for dot files. */
        if (sbi->options->hide_dot_files && name->name[0] == '.')
                fa |= FILE_ATTRIBUTE_HIDDEN;

        if (!(mode & 0222))
                fa |= FILE_ATTRIBUTE_READONLY;

        /* Allocate PATH_MAX bytes. */
        new_de = kzalloc(PATH_MAX, GFP_KERNEL);
        if (!new_de) {
                err = -ENOMEM;
                goto out1;
        }

        /* Avoid any operation if inode is bad. */
        if (unlikely(is_bad_ni(dir_ni))) {
                err = -EINVAL;
                goto out2;
        }

        if (unlikely(ntfs3_forced_shutdown(sb))) {
                err = -EIO;
                goto out2;
        }

        /* Mark rw ntfs as dirty. it will be cleared at umount. */
        ntfs_set_state(sbi, NTFS_DIRTY_DIRTY);

        /* Step 1: allocate and fill new mft record. */
        err = ntfs_look_free_mft(sbi, &ino, false, NULL, NULL);
        if (err)
                goto out2;

        ni = ntfs_new_inode(sbi, ino, S_ISDIR(mode) ? RECORD_FLAG_DIR : 0);
        if (IS_ERR(ni)) {
                err = PTR_ERR(ni);
                ni = NULL;
                goto out3;
        }
        inode = &ni->vfs_inode;
        inode_init_owner(idmap, inode, dir, mode);
        mode = inode->i_mode;

        ni->i_crtime = current_time(inode);

        rec = ni->mi.mrec;
        rec->hard_links = cpu_to_le16(1);
        attr = Add2Ptr(rec, le16_to_cpu(rec->attr_off));

        /* Get default security id. */
        sd = s_default_security;
        sd_size = sizeof(s_default_security);

        if (is_ntfs3(sbi)) {
                security_id = dir_ni->std_security_id;
                if (le32_to_cpu(security_id) < SECURITY_ID_FIRST) {
                        security_id = sbi->security.def_security_id;

                        if (security_id == SECURITY_ID_INVALID &&
                            !ntfs_insert_security(sbi, sd, sd_size,
                                                  &security_id, NULL))
                                sbi->security.def_security_id = security_id;
                }
        }

        /* Insert standard info. */
        std5 = Add2Ptr(attr, SIZEOF_RESIDENT);

        if (security_id == SECURITY_ID_INVALID) {
                dsize = sizeof(struct ATTR_STD_INFO);
        } else {
                dsize = sizeof(struct ATTR_STD_INFO5);
                std5->security_id = security_id;
                ni->std_security_id = security_id;
        }
        asize = SIZEOF_RESIDENT + dsize;

        attr->type = ATTR_STD;
        attr->size = cpu_to_le32(asize);
        attr->id = cpu_to_le16(aid++);
        attr->res.data_off = SIZEOF_RESIDENT_LE;
        attr->res.data_size = cpu_to_le32(dsize);

        std5->cr_time = std5->m_time = std5->c_time = std5->a_time =
                kernel2nt(&ni->i_crtime);

        std5->fa = ni->std_fa = fa;

        attr = Add2Ptr(attr, asize);

        /* Insert file name. */
        err = fill_name_de(sbi, new_de, name, uni);
        if (err)
                goto out4;

        mi_get_ref(&ni->mi, &new_de->ref);

        fname = (struct ATTR_FILE_NAME *)(new_de + 1);

        if (sbi->options->windows_names &&
            !valid_windows_name(sbi, (struct le_str *)&fname->name_len)) {
                err = -EINVAL;
                goto out4;
        }

        mi_get_ref(&dir_ni->mi, &fname->home);
        fname->dup.cr_time = fname->dup.m_time = fname->dup.c_time =
                fname->dup.a_time = std5->cr_time;
        fname->dup.alloc_size = fname->dup.data_size = 0;
        fname->dup.fa = std5->fa;
        fname->dup.extend_data = S_ISLNK(mode) ? IO_REPARSE_TAG_SYMLINK : 0;

        dsize = le16_to_cpu(new_de->key_size);
        asize = ALIGN(SIZEOF_RESIDENT + dsize, 8);

        attr->type = ATTR_NAME;
        attr->size = cpu_to_le32(asize);
        attr->res.data_off = SIZEOF_RESIDENT_LE;
        attr->res.flags = RESIDENT_FLAG_INDEXED;
        attr->id = cpu_to_le16(aid++);
        attr->res.data_size = cpu_to_le32(dsize);
        memcpy(Add2Ptr(attr, SIZEOF_RESIDENT), fname, dsize);

        attr = Add2Ptr(attr, asize);

        if (security_id == SECURITY_ID_INVALID) {
                /* Insert security attribute. */
                asize = SIZEOF_RESIDENT + ALIGN(sd_size, 8);

                attr->type = ATTR_SECURE;
                attr->size = cpu_to_le32(asize);
                attr->id = cpu_to_le16(aid++);
                attr->res.data_off = SIZEOF_RESIDENT_LE;
                attr->res.data_size = cpu_to_le32(sd_size);
                memcpy(Add2Ptr(attr, SIZEOF_RESIDENT), sd, sd_size);

                attr = Add2Ptr(attr, asize);
        }

        attr->id = cpu_to_le16(aid++);
        if (fa & FILE_ATTRIBUTE_DIRECTORY) {
                /*
                 * Regular directory or symlink to directory.
                 * Create root attribute.
                 */
                dsize = sizeof(struct INDEX_ROOT) + sizeof(struct NTFS_DE);
                asize = sizeof(I30_NAME) + SIZEOF_RESIDENT + dsize;

                attr->type = ATTR_ROOT;
                attr->size = cpu_to_le32(asize);

                attr->name_len = ARRAY_SIZE(I30_NAME);
                attr->name_off = SIZEOF_RESIDENT_LE;
                attr->res.data_off =
                        cpu_to_le16(sizeof(I30_NAME) + SIZEOF_RESIDENT);
                attr->res.data_size = cpu_to_le32(dsize);
                memcpy(Add2Ptr(attr, SIZEOF_RESIDENT), I30_NAME,
                       sizeof(I30_NAME));

                root = Add2Ptr(attr, sizeof(I30_NAME) + SIZEOF_RESIDENT);
                memcpy(root, dir_root, offsetof(struct INDEX_ROOT, ihdr));
                root->ihdr.de_off = cpu_to_le32(sizeof(struct INDEX_HDR));
                root->ihdr.used = cpu_to_le32(sizeof(struct INDEX_HDR) +
                                              sizeof(struct NTFS_DE));
                root->ihdr.total = root->ihdr.used;

                e = Add2Ptr(root, sizeof(struct INDEX_ROOT));
                e->size = cpu_to_le16(sizeof(struct NTFS_DE));
                e->flags = NTFS_IE_LAST;
        } else if (S_ISLNK(mode)) {
                /*
                 * Symlink to file.
                 * Create empty resident data attribute.
                 */
                asize = SIZEOF_RESIDENT;

                /* Insert empty ATTR_DATA */
                attr->type = ATTR_DATA;
                attr->size = cpu_to_le32(SIZEOF_RESIDENT);
                attr->name_off = SIZEOF_RESIDENT_LE;
                attr->res.data_off = SIZEOF_RESIDENT_LE;
        } else if (!new_file_resident && S_ISREG(mode)) {
                /*
                 * Regular file. Create empty non resident data attribute.
                 */
                attr->type = ATTR_DATA;
                attr->non_res = 1;
                attr->nres.evcn = cpu_to_le64(-1ll);
                if (fa & FILE_ATTRIBUTE_SPARSE_FILE) {
                        attr->size = cpu_to_le32(SIZEOF_NONRESIDENT_EX + 8);
                        attr->name_off = SIZEOF_NONRESIDENT_EX_LE;
                        attr->flags = ATTR_FLAG_SPARSED;
                        asize = SIZEOF_NONRESIDENT_EX + 8;
                } else if (fa & FILE_ATTRIBUTE_COMPRESSED) {
                        attr->size = cpu_to_le32(SIZEOF_NONRESIDENT_EX + 8);
                        attr->name_off = SIZEOF_NONRESIDENT_EX_LE;
                        attr->flags = ATTR_FLAG_COMPRESSED;
                        attr->nres.c_unit = NTFS_LZNT_CUNIT;
                        asize = SIZEOF_NONRESIDENT_EX + 8;
                } else {
                        attr->size = cpu_to_le32(SIZEOF_NONRESIDENT + 8);
                        attr->name_off = SIZEOF_NONRESIDENT_LE;
                        asize = SIZEOF_NONRESIDENT + 8;
                }
                attr->nres.run_off = attr->name_off;
        } else {
                /*
                 * Node. Create empty resident data attribute.
                 */
                attr->type = ATTR_DATA;
                attr->size = cpu_to_le32(SIZEOF_RESIDENT);
                attr->name_off = SIZEOF_RESIDENT_LE;
                if (fa & FILE_ATTRIBUTE_SPARSE_FILE)
                        attr->flags = ATTR_FLAG_SPARSED;
                else if (fa & FILE_ATTRIBUTE_COMPRESSED)
                        attr->flags = ATTR_FLAG_COMPRESSED;
                attr->res.data_off = SIZEOF_RESIDENT_LE;
                asize = SIZEOF_RESIDENT;
                ni->ni_flags |= NI_FLAG_RESIDENT;
        }

        if (S_ISDIR(mode)) {
                ni->ni_flags |= NI_FLAG_DIR;
                err = indx_init(&ni->dir, sbi, attr, INDEX_MUTEX_I30);
                if (err)
                        goto out4;
        } else if (S_ISLNK(mode)) {
                rp = ntfs_create_reparse_buffer(sbi, symname, size, &nsize);

                if (IS_ERR(rp)) {
                        err = PTR_ERR(rp);
                        rp = NULL;
                        goto out4;
                }

                /*
                 * Insert ATTR_REPARSE.
                 */
                attr = Add2Ptr(attr, asize);
                attr->type = ATTR_REPARSE;
                attr->id = cpu_to_le16(aid++);

                /* Resident or non resident? */
                asize = ALIGN(SIZEOF_RESIDENT + nsize, 8);
                t16 = PtrOffset(rec, attr);

                /*
                 * Below function 'ntfs_save_wsl_perm' requires 0x78 bytes.
                 * It is good idea to keep extended attributes resident.
                 */
                if (asize + t16 + 0x78 + 8 > sbi->record_size) {
                        CLST alen;
                        CLST clst = bytes_to_cluster(sbi, nsize);

                        /* Bytes per runs. */
                        t16 = sbi->record_size - t16 - SIZEOF_NONRESIDENT;

                        attr->non_res = 1;
                        attr->nres.evcn = cpu_to_le64(clst - 1);
                        attr->name_off = SIZEOF_NONRESIDENT_LE;
                        attr->nres.run_off = attr->name_off;
                        attr->nres.data_size = cpu_to_le64(nsize);
                        attr->nres.valid_size = attr->nres.data_size;
                        attr->nres.alloc_size =
                                cpu_to_le64(ntfs_up_cluster(sbi, nsize));

                        err = attr_allocate_clusters(sbi, &ni->file.run, NULL,
                                                     0, 0, clst, NULL,
                                                     ALLOCATE_DEF, &alen, 0,
                                                     NULL, NULL);
                        if (err)
                                goto out5;

                        err = run_pack(&ni->file.run, 0, clst,
                                       Add2Ptr(attr, SIZEOF_NONRESIDENT), t16,
                                       &vcn);
                        if (err < 0)
                                goto out5;

                        if (vcn != clst) {
                                err = -EINVAL;
                                goto out5;
                        }

                        asize = SIZEOF_NONRESIDENT + ALIGN(err, 8);
                        /* Write non resident data. */
                        err = ntfs_sb_write_run(sbi, &ni->file.run, 0, rp,
                                                nsize, 0);
                        if (err)
                                goto out5;
                } else {
                        attr->res.data_off = SIZEOF_RESIDENT_LE;
                        attr->res.data_size = cpu_to_le32(nsize);
                        memcpy(Add2Ptr(attr, SIZEOF_RESIDENT), rp, nsize);
                }
                /* Size of symlink equals the length of input string. */
                inode->i_size = size;

                attr->size = cpu_to_le32(asize);

                err = ntfs_insert_reparse(sbi, IO_REPARSE_TAG_SYMLINK,
                                          &new_de->ref);
                if (err)
                        goto out5;

                rp_inserted = true;
        }

        attr = Add2Ptr(attr, asize);
        attr->type = ATTR_END;

        rec->used = cpu_to_le32(PtrOffset(rec, attr) + 8);
        rec->next_attr_id = cpu_to_le16(aid);

        inode->i_generation = le16_to_cpu(rec->seq);

        if (S_ISDIR(mode)) {
                inode->i_op = &ntfs_dir_inode_operations;
                inode->i_fop = unlikely(is_legacy_ntfs(sb)) ?
                                       &ntfs_legacy_dir_operations :
                                       &ntfs_dir_operations;
        } else if (S_ISLNK(mode)) {
                inode->i_op = &ntfs_link_inode_operations;
                inode->i_fop = NULL;
                inode->i_mapping->a_ops = &ntfs_aops;
                inode->i_size = size;
                inode_nohighmem(inode);
        } else if (S_ISREG(mode)) {
                inode->i_op = &ntfs_file_inode_operations;
                inode->i_fop = unlikely(is_legacy_ntfs(sb)) ?
                                       &ntfs_legacy_file_operations :
                                       &ntfs_file_operations;
                inode->i_mapping->a_ops = is_compressed(ni) ? &ntfs_aops_cmpr :
                                                              &ntfs_aops;
                init_rwsem(&ni->file.run_lock);
        } else {
                inode->i_op = &ntfs_special_inode_operations;
                init_special_inode(inode, mode, dev);
        }

#ifdef CONFIG_NTFS3_FS_POSIX_ACL
        if (!S_ISLNK(mode) && (sb->s_flags & SB_POSIXACL)) {
                err = ntfs_init_acl(idmap, inode, dir);
                if (err)
                        goto out5;
        } else
#endif
        {
                inode->i_flags |= S_NOSEC;
        }

        if (!S_ISLNK(mode)) {
                /*
                 * ntfs_init_acl and ntfs_save_wsl_perm update extended attribute.
                 * The packed size of extended attribute is stored in direntry too.
                 * 'fname' here points to inside new_de.
                 */
                err = ntfs_save_wsl_perm(inode, &fname->dup.extend_data);
                if (err)
                        goto out6;

                /*
                 * update ea_size in file_name attribute too.
                 * Use ni_find_attr cause layout of MFT record may be changed
                 * in ntfs_init_acl and ntfs_save_wsl_perm.
                 */
                attr = ni_find_attr(ni, NULL, NULL, ATTR_NAME, NULL, 0, NULL,
                                    NULL);
                if (attr) {
                        struct ATTR_FILE_NAME *fn;

                        fn = resident_data_ex(attr, SIZEOF_ATTRIBUTE_FILENAME);
                        if (fn)
                                fn->dup.extend_data = fname->dup.extend_data;
                }
        }

        /* We do not need to update parent directory later */
        ni->ni_flags &= ~NI_FLAG_UPDATE_PARENT;

        /* Step 2: Add new name in index. */
        err = indx_insert_entry(&dir_ni->dir, dir_ni, new_de, sbi, fnd, 0);
        if (err)
                goto out6;

        /*
         * Call 'd_instantiate' after inode->i_op is set
         * but before finish_open.
         */
        d_instantiate(dentry, inode);

        /* Set original time. inode times (i_ctime) may be changed in ntfs_init_acl. */
        inode_set_atime_to_ts(inode, ni->i_crtime);
        inode_set_ctime_to_ts(inode, ni->i_crtime);
        inode_set_mtime_to_ts(inode, ni->i_crtime);
        inode_set_mtime_to_ts(dir, ni->i_crtime);
        inode_set_ctime_to_ts(dir, ni->i_crtime);

        mark_inode_dirty(dir);
        mark_inode_dirty(inode);

        /* Normal exit. */
        goto out2;

out6:
        attr = ni_find_attr(ni, NULL, NULL, ATTR_EA, NULL, 0, NULL, NULL);
        if (attr && attr->non_res) {
                /* Delete ATTR_EA, if non-resident. */
                struct runs_tree run;
                run_init(&run);
                attr_set_size(ni, ATTR_EA, NULL, 0, &run, 0, NULL, false);
                run_close(&run);
        }

        if (rp_inserted)
                ntfs_remove_reparse(sbi, IO_REPARSE_TAG_SYMLINK, &new_de->ref);

out5:
        if (!S_ISDIR(mode))
                run_deallocate(sbi, &ni->file.run, false);

out4:
        clear_rec_inuse(rec);
        clear_nlink(inode);
        ni->mi.dirty = false;
        discard_new_inode(inode);
out3:
        ntfs_mark_rec_free(sbi, ino, false);

out2:
        kfree(new_de);
        kfree(rp);

out1:
        if (!fnd)
                ni_unlock(dir_ni);

        if (!err)
                unlock_new_inode(inode);

        return err;
}

int ntfs_link_inode(struct inode *inode, struct dentry *dentry)
{
        int err;
        struct ntfs_inode *ni = ntfs_i(inode);
        struct ntfs_sb_info *sbi = inode->i_sb->s_fs_info;
        struct NTFS_DE *de;

        /* Allocate PATH_MAX bytes. */
        de = kzalloc(PATH_MAX, GFP_KERNEL);
        if (!de)
                return -ENOMEM;

        /* Mark rw ntfs as dirty. It will be cleared at umount. */
        ntfs_set_state(sbi, NTFS_DIRTY_DIRTY);

        /* Construct 'de'. */
        err = fill_name_de(sbi, de, &dentry->d_name, NULL);
        if (err)
                goto out;

        err = ni_add_name(ntfs_i(d_inode(dentry->d_parent)), ni, de);
out:
        kfree(de);
        return err;
}

/*
 * ntfs_unlink_inode
 *
 * inode_operations::unlink
 * inode_operations::rmdir
 */
int ntfs_unlink_inode(struct inode *dir, const struct dentry *dentry)
{
        int err;
        struct ntfs_sb_info *sbi = dir->i_sb->s_fs_info;
        struct inode *inode = d_inode(dentry);
        struct ntfs_inode *ni = ntfs_i(inode);
        struct ntfs_inode *dir_ni = ntfs_i(dir);
        struct NTFS_DE *de, *de2 = NULL;
        int undo_remove;

        if (ntfs_is_meta_file(sbi, ni->mi.rno))
                return -EINVAL;

        de = kzalloc(PATH_MAX, GFP_KERNEL);
        if (!de)
                return -ENOMEM;

        ni_lock(ni);

        if (S_ISDIR(inode->i_mode) && !dir_is_empty(inode)) {
                err = -ENOTEMPTY;
                goto out;
        }

        err = fill_name_de(sbi, de, &dentry->d_name, NULL);
        if (err < 0)
                goto out;

        undo_remove = 0;
        err = ni_remove_name(dir_ni, ni, de, &de2, &undo_remove);

        if (!err) {
                drop_nlink(inode);
                inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
                mark_inode_dirty(dir);
                inode_set_ctime_to_ts(inode, inode_get_ctime(dir));
                if (inode->i_nlink)
                        mark_inode_dirty(inode);
        } else if (!ni_remove_name_undo(dir_ni, ni, de, de2, undo_remove)) {
                _ntfs_bad_inode(inode);
        } else {
                if (ni_is_dirty(dir))
                        mark_inode_dirty(dir);
                if (ni_is_dirty(inode))
                        mark_inode_dirty(inode);
        }

out:
        ni_unlock(ni);
        kfree(de);
        return err;
}

void ntfs_evict_inode(struct inode *inode)
{
        truncate_inode_pages_final(&inode->i_data);

        invalidate_inode_buffers(inode);
        clear_inode(inode);

        ni_clear(ntfs_i(inode));
}

/*
 * ntfs_translate_junction
 *
 * Translate a Windows junction target to the Linux equivalent.
 * On junctions, targets are always absolute (they include the drive
 * letter). We have no way of knowing if the target is for the current
 * mounted device or not so we just assume it is.
 */
static int ntfs_translate_junction(const struct super_block *sb,
                                   const struct dentry *link_de, char *target,
                                   int target_len, int target_max)
{
        int tl_len, err = target_len;
        char *link_path_buffer = NULL, *link_path;
        char *translated = NULL;
        char *target_start;
        int copy_len;

        link_path_buffer = kmalloc(PATH_MAX, GFP_NOFS);
        if (!link_path_buffer) {
                err = -ENOMEM;
                goto out;
        }
        /* Get link path, relative to mount point */
        link_path = dentry_path_raw(link_de, link_path_buffer, PATH_MAX);
        if (IS_ERR(link_path)) {
                ntfs_err(sb, "Error getting link path");
                err = -EINVAL;
                goto out;
        }

        translated = kmalloc(PATH_MAX, GFP_NOFS);
        if (!translated) {
                err = -ENOMEM;
                goto out;
        }

        /* Make translated path a relative path to mount point */
        strcpy(translated, "./");
        ++link_path; /* Skip leading / */
        for (tl_len = sizeof("./") - 1; *link_path; ++link_path) {
                if (*link_path == '/') {
                        if (PATH_MAX - tl_len < sizeof("../")) {
                                ntfs_err(sb,
                                         "Link path %s has too many components",
                                         link_path);
                                err = -EINVAL;
                                goto out;
                        }
                        strcpy(translated + tl_len, "../");
                        tl_len += sizeof("../") - 1;
                }
        }

        /* Skip drive letter */
        target_start = target;
        while (*target_start && *target_start != ':')
                ++target_start;

        if (!*target_start) {
                ntfs_err(sb, "Link target (%s) missing drive separator",
                         target);
                err = -EINVAL;
                goto out;
        }

        /* Skip drive separator and leading /, if exists */
        target_start += 1 + (target_start[1] == '/');
        copy_len = target_len - (target_start - target);

        if (PATH_MAX - tl_len <= copy_len) {
                ntfs_err(sb, "Link target %s too large for buffer (%d <= %d)",
                         target_start, PATH_MAX - tl_len, copy_len);
                err = -EINVAL;
                goto out;
        }

        /* translated path has a trailing / and target_start does not */
        strcpy(translated + tl_len, target_start);
        tl_len += copy_len;
        if (target_max <= tl_len) {
                ntfs_err(sb, "Target path %s too large for buffer (%d <= %d)",
                         translated, target_max, tl_len);
                err = -EINVAL;
                goto out;
        }
        strcpy(target, translated);
        err = tl_len;

out:
        kfree(link_path_buffer);
        kfree(translated);
        return err;
}

static noinline int ntfs_readlink_hlp(const struct dentry *link_de,
                                      struct inode *inode, char *buffer,
                                      int buflen)
{
        int i, err = -EINVAL;
        struct ntfs_inode *ni = ntfs_i(inode);
        struct super_block *sb = inode->i_sb;
        struct ntfs_sb_info *sbi = sb->s_fs_info;
        u64 size;
        u16 ulen = 0;
        void *to_free = NULL;
        struct REPARSE_DATA_BUFFER *rp;
        const __le16 *uname;
        struct ATTRIB *attr;

        /* Reparse data present. Try to parse it. */
        static_assert(!offsetof(struct REPARSE_DATA_BUFFER, ReparseTag));
        static_assert(sizeof(u32) == sizeof(rp->ReparseTag));

        *buffer = 0;

        attr = ni_find_attr(ni, NULL, NULL, ATTR_REPARSE, NULL, 0, NULL, NULL);
        if (!attr)
                goto out;

        if (!attr->non_res) {
                rp = resident_data_ex(attr, sizeof(struct REPARSE_DATA_BUFFER));
                if (!rp)
                        goto out;
                size = le32_to_cpu(attr->res.data_size);
        } else {
                size = le64_to_cpu(attr->nres.data_size);
                rp = NULL;
        }

        if (size > sbi->reparse.max_size || size <= sizeof(u32))
                goto out;

        if (!rp) {
                rp = kmalloc(size, GFP_NOFS);
                if (!rp) {
                        err = -ENOMEM;
                        goto out;
                }
                to_free = rp;
                /* Read into temporal buffer. */
                err = ntfs_read_run_nb(sbi, &ni->file.run, 0, rp, size, NULL);
                if (err)
                        goto out;
        }

        /* Microsoft Tag. */
        switch (rp->ReparseTag) {
        case IO_REPARSE_TAG_MOUNT_POINT:
                /* Mount points and junctions. */
                /* Can we use 'Rp->MountPointReparseBuffer.PrintNameLength'? */
                if (size <= offsetof(struct REPARSE_DATA_BUFFER,
                                     MountPointReparseBuffer.PathBuffer))
                        goto out;
                uname = Add2Ptr(rp,
                                offsetof(struct REPARSE_DATA_BUFFER,
                                         MountPointReparseBuffer.PathBuffer) +
                                        le16_to_cpu(rp->MountPointReparseBuffer
                                                            .PrintNameOffset));
                ulen = le16_to_cpu(rp->MountPointReparseBuffer.PrintNameLength);
                break;

        case IO_REPARSE_TAG_SYMLINK:
                /* FolderSymbolicLink */
                /* Can we use 'Rp->SymbolicLinkReparseBuffer.PrintNameLength'? */
                if (size <= offsetof(struct REPARSE_DATA_BUFFER,
                                     SymbolicLinkReparseBuffer.PathBuffer))
                        goto out;
                uname = Add2Ptr(
                        rp, offsetof(struct REPARSE_DATA_BUFFER,
                                     SymbolicLinkReparseBuffer.PathBuffer) +
                                    le16_to_cpu(rp->SymbolicLinkReparseBuffer
                                                        .PrintNameOffset));
                ulen = le16_to_cpu(
                        rp->SymbolicLinkReparseBuffer.PrintNameLength);
                break;

        case IO_REPARSE_TAG_CLOUD:
        case IO_REPARSE_TAG_CLOUD_1:
        case IO_REPARSE_TAG_CLOUD_2:
        case IO_REPARSE_TAG_CLOUD_3:
        case IO_REPARSE_TAG_CLOUD_4:
        case IO_REPARSE_TAG_CLOUD_5:
        case IO_REPARSE_TAG_CLOUD_6:
        case IO_REPARSE_TAG_CLOUD_7:
        case IO_REPARSE_TAG_CLOUD_8:
        case IO_REPARSE_TAG_CLOUD_9:
        case IO_REPARSE_TAG_CLOUD_A:
        case IO_REPARSE_TAG_CLOUD_B:
        case IO_REPARSE_TAG_CLOUD_C:
        case IO_REPARSE_TAG_CLOUD_D:
        case IO_REPARSE_TAG_CLOUD_E:
        case IO_REPARSE_TAG_CLOUD_F:
                err = sizeof("OneDrive") - 1;
                if (err > buflen)
                        err = buflen;
                memcpy(buffer, "OneDrive", err);
                goto out;

        default:
                if (IsReparseTagMicrosoft(rp->ReparseTag)) {
                        /* Unknown Microsoft Tag. */
                        goto out;
                }
                if (!IsReparseTagNameSurrogate(rp->ReparseTag) ||
                    size <= sizeof(struct REPARSE_POINT)) {
                        goto out;
                }

                /* Users tag. */
                uname = Add2Ptr(rp, sizeof(struct REPARSE_POINT));
                ulen = le16_to_cpu(rp->ReparseDataLength) -
                       sizeof(struct REPARSE_POINT);
        }

        /* Convert nlen from bytes to UNICODE chars. */
        ulen >>= 1;

        /* Check that name is available. */
        if (!ulen || uname + ulen > (__le16 *)Add2Ptr(rp, size))
                goto out;

        /* If name is already zero terminated then truncate it now. */
        if (!uname[ulen - 1])
                ulen -= 1;

        err = ntfs_utf16_to_nls(sbi, uname, ulen, buffer, buflen);

        if (err < 0)
                goto out;

        /* Translate Windows '\' into Linux '/'. */
        for (i = 0; i < err; i++) {
                if (buffer[i] == '\\')
                        buffer[i] = '/';
        }

        /* Always set last zero. */
        buffer[err] = 0;

        /* If this is a junction, translate the link target. */
        if (rp->ReparseTag == IO_REPARSE_TAG_MOUNT_POINT)
                err = ntfs_translate_junction(sb, link_de, buffer, err, buflen);

out:
        kfree(to_free);
        return err;
}

static const char *ntfs_get_link(struct dentry *de, struct inode *inode,
                                 struct delayed_call *done)
{
        int err;
        char *ret;

        if (!de)
                return ERR_PTR(-ECHILD);

        ret = kmalloc(PAGE_SIZE, GFP_NOFS);
        if (!ret)
                return ERR_PTR(-ENOMEM);

        err = ntfs_readlink_hlp(de, inode, ret, PAGE_SIZE);
        if (err < 0) {
                kfree(ret);
                return ERR_PTR(err);
        }

        set_delayed_call(done, kfree_link, ret);

        return ret;
}

// clang-format off
const struct inode_operations ntfs_link_inode_operations = {
        .get_link       = ntfs_get_link,
        .setattr        = ntfs_setattr,
        .listxattr      = ntfs_listxattr,
};

const struct address_space_operations ntfs_aops = {
        .read_folio     = ntfs_read_folio,
        .readahead      = ntfs_readahead,
        .writepages     = ntfs_writepages,
        .bmap           = ntfs_bmap,
        .dirty_folio    = iomap_dirty_folio,
        .migrate_folio  = filemap_migrate_folio,
        .release_folio  = iomap_release_folio,
        .invalidate_folio = iomap_invalidate_folio,
};

const struct address_space_operations ntfs_aops_cmpr = {
        .read_folio     = ntfs_read_folio,
        .dirty_folio    = iomap_dirty_folio,
        .release_folio  = iomap_release_folio,
        .invalidate_folio = iomap_invalidate_folio,
};

const struct iomap_ops ntfs_iomap_ops = {
        .iomap_begin    = ntfs_iomap_begin,
        .iomap_end      = ntfs_iomap_end,
};

const struct iomap_write_ops ntfs_iomap_folio_ops = {
        .put_folio = ntfs_iomap_put_folio,
};
// clang-format on