// SPDX-License-Identifier: GPL-2.0+
/*
 * NILFS regular file handling primitives including fsync().
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * Written by Amagai Yoshiji and Ryusuke Konishi.
 */

#include <linux/fs.h>
#include <linux/filelock.h>
#include <linux/mm.h>
#include <linux/writeback.h>
#include "nilfs.h"
#include "segment.h"

int nilfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
{
        /*
         * Called from fsync() system call
         * This is the only entry point that can catch write and synch
         * timing for both data blocks and intermediate blocks.
         *
         * This function should be implemented when the writeback function
         * will be implemented.
         */
        struct the_nilfs *nilfs;
        struct inode *inode = file->f_mapping->host;
        int err = 0;

        if (nilfs_inode_dirty(inode)) {
                if (datasync)
                        err = nilfs_construct_dsync_segment(inode->i_sb, inode,
                                                            start, end);
                else
                        err = nilfs_construct_segment(inode->i_sb);
        }

        nilfs = inode->i_sb->s_fs_info;
        if (!err)
                err = nilfs_flush_device(nilfs);

        return err;
}

static vm_fault_t nilfs_page_mkwrite(struct vm_fault *vmf)
{
        struct vm_area_struct *vma = vmf->vma;
        struct folio *folio = page_folio(vmf->page);
        struct inode *inode = file_inode(vma->vm_file);
        struct nilfs_transaction_info ti;
        struct buffer_head *bh, *head;
        int ret = 0;

        if (unlikely(nilfs_near_disk_full(inode->i_sb->s_fs_info)))
                return VM_FAULT_SIGBUS; /* -ENOSPC */

        sb_start_pagefault(inode->i_sb);
        folio_lock(folio);
        if (folio->mapping != inode->i_mapping ||
            folio_pos(folio) >= i_size_read(inode) ||
            !folio_test_uptodate(folio)) {
                folio_unlock(folio);
                ret = -EFAULT;  /* make the VM retry the fault */
                goto out;
        }

        /*
         * check to see if the folio is mapped already (no holes)
         */
        if (folio_test_mappedtodisk(folio))
                goto mapped;

        head = folio_buffers(folio);
        if (head) {
                int fully_mapped = 1;

                bh = head;
                do {
                        if (!buffer_mapped(bh)) {
                                fully_mapped = 0;
                                break;
                        }
                } while (bh = bh->b_this_page, bh != head);

                if (fully_mapped) {
                        folio_set_mappedtodisk(folio);
                        goto mapped;
                }
        }
        folio_unlock(folio);

        /*
         * fill hole blocks
         */
        ret = nilfs_transaction_begin(inode->i_sb, &ti, 1);
        /* never returns -ENOMEM, but may return -ENOSPC */
        if (unlikely(ret))
                goto out;

        file_update_time(vma->vm_file);
        ret = block_page_mkwrite(vma, vmf, nilfs_get_block);
        if (ret) {
                nilfs_transaction_abort(inode->i_sb);
                goto out;
        }
        nilfs_set_file_dirty(inode, 1 << (PAGE_SHIFT - inode->i_blkbits));
        nilfs_transaction_commit(inode->i_sb);

 mapped:
        /*
         * Since checksumming including data blocks is performed to determine
         * the validity of the log to be written and used for recovery, it is
         * necessary to wait for writeback to finish here, regardless of the
         * stable write requirement of the backing device.
         */
        folio_wait_writeback(folio);
 out:
        sb_end_pagefault(inode->i_sb);
        return vmf_fs_error(ret);
}

static const struct vm_operations_struct nilfs_file_vm_ops = {
        .fault          = filemap_fault,
        .map_pages      = filemap_map_pages,
        .page_mkwrite   = nilfs_page_mkwrite,
};

static int nilfs_file_mmap_prepare(struct vm_area_desc *desc)
{
        file_accessed(desc->file);
        desc->vm_ops = &nilfs_file_vm_ops;
        return 0;
}

/*
 * We have mostly NULL's here: the current defaults are ok for
 * the nilfs filesystem.
 */
const struct file_operations nilfs_file_operations = {
        .llseek         = generic_file_llseek,
        .read_iter      = generic_file_read_iter,
        .write_iter     = generic_file_write_iter,
        .unlocked_ioctl = nilfs_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = nilfs_compat_ioctl,
#endif  /* CONFIG_COMPAT */
        .mmap_prepare   = nilfs_file_mmap_prepare,
        .open           = generic_file_open,
        /* .release     = nilfs_release_file, */
        .fsync          = nilfs_sync_file,
        .splice_read    = filemap_splice_read,
        .splice_write   = iter_file_splice_write,
        .setlease       = generic_setlease,
};

const struct inode_operations nilfs_file_inode_operations = {
        .setattr        = nilfs_setattr,
        .permission     = nilfs_permission,
        .fiemap         = nilfs_fiemap,
        .fileattr_get   = nilfs_fileattr_get,
        .fileattr_set   = nilfs_fileattr_set,
};

/* end of file */