// SPDX-License-Identifier: GPL-2.0
/*
 *
 * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
 *
 *  Regular file handling primitives for NTFS-based filesystems.
 *
 */

#include <linux/backing-dev.h>
#include <linux/blkdev.h>
#include <linux/buffer_head.h>
#include <linux/compat.h>
#include <linux/falloc.h>
#include <linux/fiemap.h>

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

static int ntfs_ioctl_fitrim(struct ntfs_sb_info *sbi, unsigned long arg)
{
        struct fstrim_range __user *user_range;
        struct fstrim_range range;
        int err;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (!bdev_max_discard_sectors(sbi->sb->s_bdev))
                return -EOPNOTSUPP;

        user_range = (struct fstrim_range __user *)arg;
        if (copy_from_user(&range, user_range, sizeof(range)))
                return -EFAULT;

        range.minlen = max_t(u32, range.minlen,
                             bdev_discard_granularity(sbi->sb->s_bdev));

        err = ntfs_trim_fs(sbi, &range);
        if (err < 0)
                return err;

        if (copy_to_user(user_range, &range, sizeof(range)))
                return -EFAULT;

        return 0;
}

static long ntfs_ioctl(struct file *filp, u32 cmd, unsigned long arg)
{
        struct inode *inode = file_inode(filp);
        struct ntfs_sb_info *sbi = inode->i_sb->s_fs_info;

        switch (cmd) {
        case FITRIM:
                return ntfs_ioctl_fitrim(sbi, arg);
        }
        return -ENOTTY; /* Inappropriate ioctl for device. */
}

#ifdef CONFIG_COMPAT
static long ntfs_compat_ioctl(struct file *filp, u32 cmd, unsigned long arg)

{
        return ntfs_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
}
#endif

/*
 * ntfs_getattr - inode_operations::getattr
 */
int ntfs_getattr(struct user_namespace *mnt_userns, const struct path *path,
                 struct kstat *stat, u32 request_mask, u32 flags)
{
        struct inode *inode = d_inode(path->dentry);
        struct ntfs_inode *ni = ntfs_i(inode);

        if (is_compressed(ni))
                stat->attributes |= STATX_ATTR_COMPRESSED;

        if (is_encrypted(ni))
                stat->attributes |= STATX_ATTR_ENCRYPTED;

        stat->attributes_mask |= STATX_ATTR_COMPRESSED | STATX_ATTR_ENCRYPTED;

        generic_fillattr(mnt_userns, inode, stat);

        stat->result_mask |= STATX_BTIME;
        stat->btime = ni->i_crtime;
        stat->blksize = ni->mi.sbi->cluster_size; /* 512, 1K, ..., 2M */

        return 0;
}

static int ntfs_extend_initialized_size(struct file *file,
                                        struct ntfs_inode *ni,
                                        const loff_t valid,
                                        const loff_t new_valid)
{
        struct inode *inode = &ni->vfs_inode;
        struct address_space *mapping = inode->i_mapping;
        struct ntfs_sb_info *sbi = inode->i_sb->s_fs_info;
        loff_t pos = valid;
        int err;

        if (is_resident(ni)) {
                ni->i_valid = new_valid;
                return 0;
        }

        WARN_ON(is_compressed(ni));
        WARN_ON(valid >= new_valid);

        for (;;) {
                u32 zerofrom, len;
                struct page *page;
                u8 bits;
                CLST vcn, lcn, clen;

                if (is_sparsed(ni)) {
                        bits = sbi->cluster_bits;
                        vcn = pos >> bits;

                        err = attr_data_get_block(ni, vcn, 0, &lcn, &clen,
                                                  NULL);
                        if (err)
                                goto out;

                        if (lcn == SPARSE_LCN) {
                                loff_t vbo = (loff_t)vcn << bits;
                                loff_t to = vbo + ((loff_t)clen << bits);

                                if (to <= new_valid) {
                                        ni->i_valid = to;
                                        pos = to;
                                        goto next;
                                }

                                if (vbo < pos) {
                                        pos = vbo;
                                } else {
                                        to = (new_valid >> bits) << bits;
                                        if (pos < to) {
                                                ni->i_valid = to;
                                                pos = to;
                                                goto next;
                                        }
                                }
                        }
                }

                zerofrom = pos & (PAGE_SIZE - 1);
                len = PAGE_SIZE - zerofrom;

                if (pos + len > new_valid)
                        len = new_valid - pos;

                err = ntfs_write_begin(file, mapping, pos, len, &page, NULL);
                if (err)
                        goto out;

                zero_user_segment(page, zerofrom, PAGE_SIZE);

                /* This function in any case puts page. */
                err = ntfs_write_end(file, mapping, pos, len, len, page, NULL);
                if (err < 0)
                        goto out;
                pos += len;

next:
                if (pos >= new_valid)
                        break;

                balance_dirty_pages_ratelimited(mapping);
                cond_resched();
        }

        return 0;

out:
        ni->i_valid = valid;
        ntfs_inode_warn(inode, "failed to extend initialized size to %llx.",
                        new_valid);
        return err;
}

/*
 * ntfs_zero_range - Helper function for punch_hole.
 *
 * It zeroes a range [vbo, vbo_to).
 */
static int ntfs_zero_range(struct inode *inode, u64 vbo, u64 vbo_to)
{
        int err = 0;
        struct address_space *mapping = inode->i_mapping;
        u32 blocksize = 1 << inode->i_blkbits;
        pgoff_t idx = vbo >> PAGE_SHIFT;
        u32 z_start = vbo & (PAGE_SIZE - 1);
        pgoff_t idx_end = (vbo_to + PAGE_SIZE - 1) >> PAGE_SHIFT;
        loff_t page_off;
        struct buffer_head *head, *bh;
        u32 bh_next, bh_off, z_end;
        sector_t iblock;
        struct page *page;

        for (; idx < idx_end; idx += 1, z_start = 0) {
                page_off = (loff_t)idx << PAGE_SHIFT;
                z_end = (page_off + PAGE_SIZE) > vbo_to ? (vbo_to - page_off)
                                                        : PAGE_SIZE;
                iblock = page_off >> inode->i_blkbits;

                page = find_or_create_page(mapping, idx,
                                           mapping_gfp_constraint(mapping,
                                                                  ~__GFP_FS));
                if (!page)
                        return -ENOMEM;

                if (!page_has_buffers(page))
                        create_empty_buffers(page, blocksize, 0);

                bh = head = page_buffers(page);
                bh_off = 0;
                do {
                        bh_next = bh_off + blocksize;

                        if (bh_next <= z_start || bh_off >= z_end)
                                continue;

                        if (!buffer_mapped(bh)) {
                                ntfs_get_block(inode, iblock, bh, 0);
                                /* Unmapped? It's a hole - nothing to do. */
                                if (!buffer_mapped(bh))
                                        continue;
                        }

                        /* Ok, it's mapped. Make sure it's up-to-date. */
                        if (PageUptodate(page))
                                set_buffer_uptodate(bh);

                        if (!buffer_uptodate(bh)) {
                                lock_buffer(bh);
                                bh->b_end_io = end_buffer_read_sync;
                                get_bh(bh);
                                submit_bh(REQ_OP_READ, 0, bh);

                                wait_on_buffer(bh);
                                if (!buffer_uptodate(bh)) {
                                        unlock_page(page);
                                        put_page(page);
                                        err = -EIO;
                                        goto out;
                                }
                        }

                        mark_buffer_dirty(bh);

                } while (bh_off = bh_next, iblock += 1,
                         head != (bh = bh->b_this_page));

                zero_user_segment(page, z_start, z_end);

                unlock_page(page);
                put_page(page);
                cond_resched();
        }
out:
        mark_inode_dirty(inode);
        return err;
}

/*
 * ntfs_sparse_cluster - Helper function to zero a new allocated clusters.
 *
 * NOTE: 512 <= cluster size <= 2M
 */
void ntfs_sparse_cluster(struct inode *inode, struct page *page0, CLST vcn,
                         CLST len)
{
        struct address_space *mapping = inode->i_mapping;
        struct ntfs_sb_info *sbi = inode->i_sb->s_fs_info;
        u64 vbo = (u64)vcn << sbi->cluster_bits;
        u64 bytes = (u64)len << sbi->cluster_bits;
        u32 blocksize = 1 << inode->i_blkbits;
        pgoff_t idx0 = page0 ? page0->index : -1;
        loff_t vbo_clst = vbo & sbi->cluster_mask_inv;
        loff_t end = ntfs_up_cluster(sbi, vbo + bytes);
        pgoff_t idx = vbo_clst >> PAGE_SHIFT;
        u32 from = vbo_clst & (PAGE_SIZE - 1);
        pgoff_t idx_end = (end + PAGE_SIZE - 1) >> PAGE_SHIFT;
        loff_t page_off;
        u32 to;
        bool partial;
        struct page *page;

        for (; idx < idx_end; idx += 1, from = 0) {
                page = idx == idx0 ? page0 : grab_cache_page(mapping, idx);

                if (!page)
                        continue;

                page_off = (loff_t)idx << PAGE_SHIFT;
                to = (page_off + PAGE_SIZE) > end ? (end - page_off)
                                                  : PAGE_SIZE;
                partial = false;

                if ((from || PAGE_SIZE != to) &&
                    likely(!page_has_buffers(page))) {
                        create_empty_buffers(page, blocksize, 0);
                }

                if (page_has_buffers(page)) {
                        struct buffer_head *head, *bh;
                        u32 bh_off = 0;

                        bh = head = page_buffers(page);
                        do {
                                u32 bh_next = bh_off + blocksize;

                                if (from <= bh_off && bh_next <= to) {
                                        set_buffer_uptodate(bh);
                                        mark_buffer_dirty(bh);
                                } else if (!buffer_uptodate(bh)) {
                                        partial = true;
                                }
                                bh_off = bh_next;
                        } while (head != (bh = bh->b_this_page));
                }

                zero_user_segment(page, from, to);

                if (!partial) {
                        if (!PageUptodate(page))
                                SetPageUptodate(page);
                        set_page_dirty(page);
                }

                if (idx != idx0) {
                        unlock_page(page);
                        put_page(page);
                }
                cond_resched();
        }
        mark_inode_dirty(inode);
}

/*
 * ntfs_file_mmap - file_operations::mmap
 */
static int ntfs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
        struct address_space *mapping = file->f_mapping;
        struct inode *inode = mapping->host;
        struct ntfs_inode *ni = ntfs_i(inode);
        u64 from = ((u64)vma->vm_pgoff << PAGE_SHIFT);
        bool rw = vma->vm_flags & VM_WRITE;
        int err;

        if (is_encrypted(ni)) {
                ntfs_inode_warn(inode, "mmap encrypted not supported");
                return -EOPNOTSUPP;
        }

        if (is_dedup(ni)) {
                ntfs_inode_warn(inode, "mmap deduplicated not supported");
                return -EOPNOTSUPP;
        }

        if (is_compressed(ni) && rw) {
                ntfs_inode_warn(inode, "mmap(write) compressed not supported");
                return -EOPNOTSUPP;
        }

        if (rw) {
                u64 to = min_t(loff_t, i_size_read(inode),
                               from + vma->vm_end - vma->vm_start);

                if (is_sparsed(ni)) {
                        /* Allocate clusters for rw map. */
                        struct ntfs_sb_info *sbi = inode->i_sb->s_fs_info;
                        CLST lcn, len;
                        CLST vcn = from >> sbi->cluster_bits;
                        CLST end = bytes_to_cluster(sbi, to);
                        bool new;

                        for (; vcn < end; vcn += len) {
                                err = attr_data_get_block(ni, vcn, 1, &lcn,
                                                          &len, &new);
                                if (err)
                                        goto out;

                                if (!new)
                                        continue;
                                ntfs_sparse_cluster(inode, NULL, vcn, 1);
                        }
                }

                if (ni->i_valid < to) {
                        if (!inode_trylock(inode)) {
                                err = -EAGAIN;
                                goto out;
                        }
                        err = ntfs_extend_initialized_size(file, ni,
                                                           ni->i_valid, to);
                        inode_unlock(inode);
                        if (err)
                                goto out;
                }
        }

        err = generic_file_mmap(file, vma);
out:
        return err;
}

static int ntfs_extend(struct inode *inode, loff_t pos, size_t count,
                       struct file *file)
{
        struct ntfs_inode *ni = ntfs_i(inode);
        struct address_space *mapping = inode->i_mapping;
        loff_t end = pos + count;
        bool extend_init = file && pos > ni->i_valid;
        int err;

        if (end <= inode->i_size && !extend_init)
                return 0;

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

        if (end > inode->i_size) {
                err = ntfs_set_size(inode, end);
                if (err)
                        goto out;
                inode->i_size = end;
        }

        if (extend_init && !is_compressed(ni)) {
                err = ntfs_extend_initialized_size(file, ni, ni->i_valid, pos);
                if (err)
                        goto out;
        } else {
                err = 0;
        }

        inode->i_ctime = inode->i_mtime = current_time(inode);
        mark_inode_dirty(inode);

        if (IS_SYNC(inode)) {
                int err2;

                err = filemap_fdatawrite_range(mapping, pos, end - 1);
                err2 = sync_mapping_buffers(mapping);
                if (!err)
                        err = err2;
                err2 = write_inode_now(inode, 1);
                if (!err)
                        err = err2;
                if (!err)
                        err = filemap_fdatawait_range(mapping, pos, end - 1);
        }

out:
        return err;
}

static int ntfs_truncate(struct inode *inode, loff_t new_size)
{
        struct super_block *sb = inode->i_sb;
        struct ntfs_inode *ni = ntfs_i(inode);
        int err, dirty = 0;
        u64 new_valid;

        if (!S_ISREG(inode->i_mode))
                return 0;

        if (is_compressed(ni)) {
                if (ni->i_valid > new_size)
                        ni->i_valid = new_size;
        } else {
                err = block_truncate_page(inode->i_mapping, new_size,
                                          ntfs_get_block);
                if (err)
                        return err;
        }

        new_valid = ntfs_up_block(sb, min_t(u64, ni->i_valid, new_size));

        ni_lock(ni);

        truncate_setsize(inode, new_size);

        down_write(&ni->file.run_lock);
        err = attr_set_size(ni, ATTR_DATA, NULL, 0, &ni->file.run, new_size,
                            &new_valid, ni->mi.sbi->options->prealloc, NULL);
        up_write(&ni->file.run_lock);

        if (new_valid < ni->i_valid)
                ni->i_valid = new_valid;

        ni_unlock(ni);

        ni->std_fa |= FILE_ATTRIBUTE_ARCHIVE;
        inode->i_ctime = inode->i_mtime = current_time(inode);
        if (!IS_DIRSYNC(inode)) {
                dirty = 1;
        } else {
                err = ntfs_sync_inode(inode);
                if (err)
                        return err;
        }

        if (dirty)
                mark_inode_dirty(inode);

        /*ntfs_flush_inodes(inode->i_sb, inode, NULL);*/

        return 0;
}

/*
 * ntfs_fallocate
 *
 * Preallocate space for a file. This implements ntfs's fallocate file
 * operation, which gets called from sys_fallocate system call. User
 * space requests 'len' bytes at 'vbo'. If FALLOC_FL_KEEP_SIZE is set
 * we just allocate clusters without zeroing them out. Otherwise we
 * allocate and zero out clusters via an expanding truncate.
 */
static long ntfs_fallocate(struct file *file, int mode, loff_t vbo, loff_t len)
{
        struct inode *inode = file->f_mapping->host;
        struct super_block *sb = inode->i_sb;
        struct ntfs_sb_info *sbi = sb->s_fs_info;
        struct ntfs_inode *ni = ntfs_i(inode);
        loff_t end = vbo + len;
        loff_t vbo_down = round_down(vbo, PAGE_SIZE);
        loff_t i_size;
        int err;

        /* No support for dir. */
        if (!S_ISREG(inode->i_mode))
                return -EOPNOTSUPP;

        /* Return error if mode is not supported. */
        if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
                     FALLOC_FL_COLLAPSE_RANGE)) {
                ntfs_inode_warn(inode, "fallocate(0x%x) is not supported",
                                mode);
                return -EOPNOTSUPP;
        }

        ntfs_set_state(sbi, NTFS_DIRTY_DIRTY);

        inode_lock(inode);
        i_size = inode->i_size;

        if (WARN_ON(ni->ni_flags & NI_FLAG_COMPRESSED_MASK)) {
                /* Should never be here, see ntfs_file_open. */
                err = -EOPNOTSUPP;
                goto out;
        }

        if (mode & FALLOC_FL_PUNCH_HOLE) {
                u32 frame_size;
                loff_t mask, vbo_a, end_a, tmp;

                if (!(mode & FALLOC_FL_KEEP_SIZE)) {
                        err = -EINVAL;
                        goto out;
                }

                err = filemap_write_and_wait_range(inode->i_mapping, vbo,
                                                   end - 1);
                if (err)
                        goto out;

                err = filemap_write_and_wait_range(inode->i_mapping, end,
                                                   LLONG_MAX);
                if (err)
                        goto out;

                inode_dio_wait(inode);

                truncate_pagecache(inode, vbo_down);

                if (!is_sparsed(ni) && !is_compressed(ni)) {
                        /*
                         * Normal file, can't make hole.
                         * TODO: Try to find way to save info about hole.
                         */
                        err = -EOPNOTSUPP;
                        goto out;
                }

                ni_lock(ni);
                err = attr_punch_hole(ni, vbo, len, &frame_size);
                ni_unlock(ni);
                if (err != E_NTFS_NOTALIGNED)
                        goto out;

                /* Process not aligned punch. */
                mask = frame_size - 1;
                vbo_a = (vbo + mask) & ~mask;
                end_a = end & ~mask;

                tmp = min(vbo_a, end);
                if (tmp > vbo) {
                        err = ntfs_zero_range(inode, vbo, tmp);
                        if (err)
                                goto out;
                }

                if (vbo < end_a && end_a < end) {
                        err = ntfs_zero_range(inode, end_a, end);
                        if (err)
                                goto out;
                }

                /* Aligned punch_hole */
                if (end_a > vbo_a) {
                        ni_lock(ni);
                        err = attr_punch_hole(ni, vbo_a, end_a - vbo_a, NULL);
                        ni_unlock(ni);
                }
        } else if (mode & FALLOC_FL_COLLAPSE_RANGE) {
                if (mode & ~FALLOC_FL_COLLAPSE_RANGE) {
                        err = -EINVAL;
                        goto out;
                }

                /*
                 * Write tail of the last page before removed range since
                 * it will get removed from the page cache below.
                 */
                err = filemap_write_and_wait_range(inode->i_mapping, vbo_down,
                                                   vbo);
                if (err)
                        goto out;

                /*
                 * Write data that will be shifted to preserve them
                 * when discarding page cache below.
                 */
                err = filemap_write_and_wait_range(inode->i_mapping, end,
                                                   LLONG_MAX);
                if (err)
                        goto out;

                /* Wait for existing dio to complete. */
                inode_dio_wait(inode);

                truncate_pagecache(inode, vbo_down);

                ni_lock(ni);
                err = attr_collapse_range(ni, vbo, len);
                ni_unlock(ni);
        } else {
                /*
                 * Normal file: Allocate clusters, do not change 'valid' size.
                 */
                loff_t new_size = max(end, i_size);

                err = inode_newsize_ok(inode, new_size);
                if (err)
                        goto out;

                err = ntfs_set_size(inode, new_size);
                if (err)
                        goto out;

                if (is_sparsed(ni) || is_compressed(ni)) {
                        CLST vcn_v = ni->i_valid >> sbi->cluster_bits;
                        CLST vcn = vbo >> sbi->cluster_bits;
                        CLST cend = bytes_to_cluster(sbi, end);
                        CLST lcn, clen;
                        bool new;

                        /*
                         * Allocate but do not zero new clusters. (see below comments)
                         * This breaks security: One can read unused on-disk areas.
                         * Zeroing these clusters may be too long.
                         * Maybe we should check here for root rights?
                         */
                        for (; vcn < cend; vcn += clen) {
                                err = attr_data_get_block(ni, vcn, cend - vcn,
                                                          &lcn, &clen, &new);
                                if (err)
                                        goto out;
                                if (!new || vcn >= vcn_v)
                                        continue;

                                /*
                                 * Unwritten area.
                                 * NTFS is not able to store several unwritten areas.
                                 * Activate 'ntfs_sparse_cluster' to zero new allocated clusters.
                                 *
                                 * Dangerous in case:
                                 * 1G of sparsed clusters + 1 cluster of data =>
                                 * valid_size == 1G + 1 cluster
                                 * fallocate(1G) will zero 1G and this can be very long
                                 * xfstest 016/086 will fail without 'ntfs_sparse_cluster'.
                                 */
                                ntfs_sparse_cluster(inode, NULL, vcn,
                                                    min(vcn_v - vcn, clen));
                        }
                }

                if (mode & FALLOC_FL_KEEP_SIZE) {
                        ni_lock(ni);
                        /* True - Keep preallocated. */
                        err = attr_set_size(ni, ATTR_DATA, NULL, 0,
                                            &ni->file.run, i_size, &ni->i_valid,
                                            true, NULL);
                        ni_unlock(ni);
                }
        }

out:
        if (err == -EFBIG)
                err = -ENOSPC;

        if (!err) {
                inode->i_ctime = inode->i_mtime = current_time(inode);
                mark_inode_dirty(inode);
        }

        inode_unlock(inode);
        return err;
}

/*
 * ntfs3_setattr - inode_operations::setattr
 */
int ntfs3_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
                  struct iattr *attr)
{
        struct super_block *sb = dentry->d_sb;
        struct ntfs_sb_info *sbi = sb->s_fs_info;
        struct inode *inode = d_inode(dentry);
        struct ntfs_inode *ni = ntfs_i(inode);
        u32 ia_valid = attr->ia_valid;
        umode_t mode = inode->i_mode;
        int err;

        if (sbi->options->noacsrules) {
                /* "No access rules" - Force any changes of time etc. */
                attr->ia_valid |= ATTR_FORCE;
                /* and disable for editing some attributes. */
                attr->ia_valid &= ~(ATTR_UID | ATTR_GID | ATTR_MODE);
                ia_valid = attr->ia_valid;
        }

        err = setattr_prepare(mnt_userns, dentry, attr);
        if (err)
                goto out;

        if (ia_valid & ATTR_SIZE) {
                loff_t oldsize = inode->i_size;

                if (WARN_ON(ni->ni_flags & NI_FLAG_COMPRESSED_MASK)) {
                        /* Should never be here, see ntfs_file_open(). */
                        err = -EOPNOTSUPP;
                        goto out;
                }
                inode_dio_wait(inode);

                if (attr->ia_size <= oldsize)
                        err = ntfs_truncate(inode, attr->ia_size);
                else if (attr->ia_size > oldsize)
                        err = ntfs_extend(inode, attr->ia_size, 0, NULL);

                if (err)
                        goto out;

                ni->ni_flags |= NI_FLAG_UPDATE_PARENT;
        }

        setattr_copy(mnt_userns, inode, attr);

        if (mode != inode->i_mode) {
                err = ntfs_acl_chmod(mnt_userns, inode);
                if (err)
                        goto out;

                /* Linux 'w' -> Windows 'ro'. */
                if (0222 & inode->i_mode)
                        ni->std_fa &= ~FILE_ATTRIBUTE_READONLY;
                else
                        ni->std_fa |= FILE_ATTRIBUTE_READONLY;
        }

        if (ia_valid & (ATTR_UID | ATTR_GID | ATTR_MODE))
                ntfs_save_wsl_perm(inode);
        mark_inode_dirty(inode);
out:
        return err;
}

static ssize_t ntfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{
        struct file *file = iocb->ki_filp;
        struct inode *inode = file->f_mapping->host;
        struct ntfs_inode *ni = ntfs_i(inode);

        if (is_encrypted(ni)) {
                ntfs_inode_warn(inode, "encrypted i/o not supported");
                return -EOPNOTSUPP;
        }

        if (is_compressed(ni) && (iocb->ki_flags & IOCB_DIRECT)) {
                ntfs_inode_warn(inode, "direct i/o + compressed not supported");
                return -EOPNOTSUPP;
        }

#ifndef CONFIG_NTFS3_LZX_XPRESS
        if (ni->ni_flags & NI_FLAG_COMPRESSED_MASK) {
                ntfs_inode_warn(
                        inode,
                        "activate CONFIG_NTFS3_LZX_XPRESS to read external compressed files");
                return -EOPNOTSUPP;
        }
#endif

        if (is_dedup(ni)) {
                ntfs_inode_warn(inode, "read deduplicated not supported");
                return -EOPNOTSUPP;
        }

        return generic_file_read_iter(iocb, iter);
}

/*
 * ntfs_get_frame_pages
 *
 * Return: Array of locked pages.
 */
static int ntfs_get_frame_pages(struct address_space *mapping, pgoff_t index,
                                struct page **pages, u32 pages_per_frame,
                                bool *frame_uptodate)
{
        gfp_t gfp_mask = mapping_gfp_mask(mapping);
        u32 npages;

        *frame_uptodate = true;

        for (npages = 0; npages < pages_per_frame; npages++, index++) {
                struct page *page;

                page = find_or_create_page(mapping, index, gfp_mask);
                if (!page) {
                        while (npages--) {
                                page = pages[npages];
                                unlock_page(page);
                                put_page(page);
                        }

                        return -ENOMEM;
                }

                if (!PageUptodate(page))
                        *frame_uptodate = false;

                pages[npages] = page;
        }

        return 0;
}

/*
 * ntfs_compress_write - Helper for ntfs_file_write_iter() (compressed files).
 */
static ssize_t ntfs_compress_write(struct kiocb *iocb, struct iov_iter *from)
{
        int err;
        struct file *file = iocb->ki_filp;
        size_t count = iov_iter_count(from);
        loff_t pos = iocb->ki_pos;
        struct inode *inode = file_inode(file);
        loff_t i_size = inode->i_size;
        struct address_space *mapping = inode->i_mapping;
        struct ntfs_inode *ni = ntfs_i(inode);
        u64 valid = ni->i_valid;
        struct ntfs_sb_info *sbi = ni->mi.sbi;
        struct page *page, **pages = NULL;
        size_t written = 0;
        u8 frame_bits = NTFS_LZNT_CUNIT + sbi->cluster_bits;
        u32 frame_size = 1u << frame_bits;
        u32 pages_per_frame = frame_size >> PAGE_SHIFT;
        u32 ip, off;
        CLST frame;
        u64 frame_vbo;
        pgoff_t index;
        bool frame_uptodate;

        if (frame_size < PAGE_SIZE) {
                /*
                 * frame_size == 8K if cluster 512
                 * frame_size == 64K if cluster 4096
                 */
                ntfs_inode_warn(inode, "page size is bigger than frame size");
                return -EOPNOTSUPP;
        }

        pages = kmalloc_array(pages_per_frame, sizeof(struct page *), GFP_NOFS);
        if (!pages)
                return -ENOMEM;

        current->backing_dev_info = inode_to_bdi(inode);
        err = file_remove_privs(file);
        if (err)
                goto out;

        err = file_update_time(file);
        if (err)
                goto out;

        /* Zero range [valid : pos). */
        while (valid < pos) {
                CLST lcn, clen;

                frame = valid >> frame_bits;
                frame_vbo = valid & ~(frame_size - 1);
                off = valid & (frame_size - 1);

                err = attr_data_get_block(ni, frame << NTFS_LZNT_CUNIT, 0, &lcn,
                                          &clen, NULL);
                if (err)
                        goto out;

                if (lcn == SPARSE_LCN) {
                        ni->i_valid = valid =
                                frame_vbo + ((u64)clen << sbi->cluster_bits);
                        continue;
                }

                /* Load full frame. */
                err = ntfs_get_frame_pages(mapping, frame_vbo >> PAGE_SHIFT,
                                           pages, pages_per_frame,
                                           &frame_uptodate);
                if (err)
                        goto out;

                if (!frame_uptodate && off) {
                        err = ni_read_frame(ni, frame_vbo, pages,
                                            pages_per_frame);
                        if (err) {
                                for (ip = 0; ip < pages_per_frame; ip++) {
                                        page = pages[ip];
                                        unlock_page(page);
                                        put_page(page);
                                }
                                goto out;
                        }
                }

                ip = off >> PAGE_SHIFT;
                off = offset_in_page(valid);
                for (; ip < pages_per_frame; ip++, off = 0) {
                        page = pages[ip];
                        zero_user_segment(page, off, PAGE_SIZE);
                        flush_dcache_page(page);
                        SetPageUptodate(page);
                }

                ni_lock(ni);
                err = ni_write_frame(ni, pages, pages_per_frame);
                ni_unlock(ni);

                for (ip = 0; ip < pages_per_frame; ip++) {
                        page = pages[ip];
                        SetPageUptodate(page);
                        unlock_page(page);
                        put_page(page);
                }

                if (err)
                        goto out;

                ni->i_valid = valid = frame_vbo + frame_size;
        }

        /* Copy user data [pos : pos + count). */
        while (count) {
                size_t copied, bytes;

                off = pos & (frame_size - 1);
                bytes = frame_size - off;
                if (bytes > count)
                        bytes = count;

                frame = pos >> frame_bits;
                frame_vbo = pos & ~(frame_size - 1);
                index = frame_vbo >> PAGE_SHIFT;

                if (unlikely(fault_in_iov_iter_readable(from, bytes))) {
                        err = -EFAULT;
                        goto out;
                }

                /* Load full frame. */
                err = ntfs_get_frame_pages(mapping, index, pages,
                                           pages_per_frame, &frame_uptodate);
                if (err)
                        goto out;

                if (!frame_uptodate) {
                        loff_t to = pos + bytes;

                        if (off || (to < i_size && (to & (frame_size - 1)))) {
                                err = ni_read_frame(ni, frame_vbo, pages,
                                                    pages_per_frame);
                                if (err) {
                                        for (ip = 0; ip < pages_per_frame;
                                             ip++) {
                                                page = pages[ip];
                                                unlock_page(page);
                                                put_page(page);
                                        }
                                        goto out;
                                }
                        }
                }

                WARN_ON(!bytes);
                copied = 0;
                ip = off >> PAGE_SHIFT;
                off = offset_in_page(pos);

                /* Copy user data to pages. */
                for (;;) {
                        size_t cp, tail = PAGE_SIZE - off;

                        page = pages[ip];
                        cp = copy_page_from_iter_atomic(page, off,
                                                        min(tail, bytes), from);
                        flush_dcache_page(page);

                        copied += cp;
                        bytes -= cp;
                        if (!bytes || !cp)
                                break;

                        if (cp < tail) {
                                off += cp;
                        } else {
                                ip++;
                                off = 0;
                        }
                }

                ni_lock(ni);
                err = ni_write_frame(ni, pages, pages_per_frame);
                ni_unlock(ni);

                for (ip = 0; ip < pages_per_frame; ip++) {
                        page = pages[ip];
                        ClearPageDirty(page);
                        SetPageUptodate(page);
                        unlock_page(page);
                        put_page(page);
                }

                if (err)
                        goto out;

                /*
                 * We can loop for a long time in here. Be nice and allow
                 * us to schedule out to avoid softlocking if preempt
                 * is disabled.
                 */
                cond_resched();

                pos += copied;
                written += copied;

                count = iov_iter_count(from);
        }

out:
        kfree(pages);

        current->backing_dev_info = NULL;

        if (err < 0)
                return err;

        iocb->ki_pos += written;
        if (iocb->ki_pos > ni->i_valid)
                ni->i_valid = iocb->ki_pos;

        return written;
}

/*
 * ntfs_file_write_iter - file_operations::write_iter
 */
static ssize_t ntfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
        struct file *file = iocb->ki_filp;
        struct address_space *mapping = file->f_mapping;
        struct inode *inode = mapping->host;
        ssize_t ret;
        struct ntfs_inode *ni = ntfs_i(inode);

        if (is_encrypted(ni)) {
                ntfs_inode_warn(inode, "encrypted i/o not supported");
                return -EOPNOTSUPP;
        }

        if (is_compressed(ni) && (iocb->ki_flags & IOCB_DIRECT)) {
                ntfs_inode_warn(inode, "direct i/o + compressed not supported");
                return -EOPNOTSUPP;
        }

        if (is_dedup(ni)) {
                ntfs_inode_warn(inode, "write into deduplicated not supported");
                return -EOPNOTSUPP;
        }

        if (!inode_trylock(inode)) {
                if (iocb->ki_flags & IOCB_NOWAIT)
                        return -EAGAIN;
                inode_lock(inode);
        }

        ret = generic_write_checks(iocb, from);
        if (ret <= 0)
                goto out;

        if (WARN_ON(ni->ni_flags & NI_FLAG_COMPRESSED_MASK)) {
                /* Should never be here, see ntfs_file_open(). */
                ret = -EOPNOTSUPP;
                goto out;
        }

        ret = ntfs_extend(inode, iocb->ki_pos, ret, file);
        if (ret)
                goto out;

        ret = is_compressed(ni) ? ntfs_compress_write(iocb, from)
                                : __generic_file_write_iter(iocb, from);

out:
        inode_unlock(inode);

        if (ret > 0)
                ret = generic_write_sync(iocb, ret);

        return ret;
}

/*
 * ntfs_file_open - file_operations::open
 */
int ntfs_file_open(struct inode *inode, struct file *file)
{
        struct ntfs_inode *ni = ntfs_i(inode);

        if (unlikely((is_compressed(ni) || is_encrypted(ni)) &&
                     (file->f_flags & O_DIRECT))) {
                return -EOPNOTSUPP;
        }

        /* Decompress "external compressed" file if opened for rw. */
        if ((ni->ni_flags & NI_FLAG_COMPRESSED_MASK) &&
            (file->f_flags & (O_WRONLY | O_RDWR | O_TRUNC))) {
#ifdef CONFIG_NTFS3_LZX_XPRESS
                int err = ni_decompress_file(ni);

                if (err)
                        return err;
#else
                ntfs_inode_warn(
                        inode,
                        "activate CONFIG_NTFS3_LZX_XPRESS to write external compressed files");
                return -EOPNOTSUPP;
#endif
        }

        return generic_file_open(inode, file);
}

/*
 * ntfs_file_release - file_operations::release
 */
static int ntfs_file_release(struct inode *inode, struct file *file)
{
        struct ntfs_inode *ni = ntfs_i(inode);
        struct ntfs_sb_info *sbi = ni->mi.sbi;
        int err = 0;

        /* If we are last writer on the inode, drop the block reservation. */
        if (sbi->options->prealloc && ((file->f_mode & FMODE_WRITE) &&
                                      atomic_read(&inode->i_writecount) == 1)) {
                ni_lock(ni);
                down_write(&ni->file.run_lock);

                err = attr_set_size(ni, ATTR_DATA, NULL, 0, &ni->file.run,
                                    inode->i_size, &ni->i_valid, false, NULL);

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

/*
 * ntfs_fiemap - file_operations::fiemap
 */
int ntfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                __u64 start, __u64 len)
{
        int err;
        struct ntfs_inode *ni = ntfs_i(inode);

        err = fiemap_prep(inode, fieinfo, start, &len, ~FIEMAP_FLAG_XATTR);
        if (err)
                return err;

        ni_lock(ni);

        err = ni_fiemap(ni, fieinfo, start, len);

        ni_unlock(ni);

        return err;
}

// clang-format off
const struct inode_operations ntfs_file_inode_operations = {
        .getattr        = ntfs_getattr,
        .setattr        = ntfs3_setattr,
        .listxattr      = ntfs_listxattr,
        .permission     = ntfs_permission,
        .get_acl        = ntfs_get_acl,
        .set_acl        = ntfs_set_acl,
        .fiemap         = ntfs_fiemap,
};

const struct file_operations ntfs_file_operations = {
        .llseek         = generic_file_llseek,
        .read_iter      = ntfs_file_read_iter,
        .write_iter     = ntfs_file_write_iter,
        .unlocked_ioctl = ntfs_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = ntfs_compat_ioctl,
#endif
        .splice_read    = generic_file_splice_read,
        .mmap           = ntfs_file_mmap,
        .open           = ntfs_file_open,
        .fsync          = generic_file_fsync,
        .splice_write   = iter_file_splice_write,
        .fallocate      = ntfs_fallocate,
        .release        = ntfs_file_release,
};
// clang-format on