/*
   * file.c - NILFS regular file handling primitives including fsync().
   *
   * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   *
   * Written by Amagai Yoshiji <amagai@osrg.net>,
   *            Ryusuke Konishi <ryusuke@osrg.net>
   */
  
  #include <linux/fs.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 int nilfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)

  {

  	struct page *page = vmf->page;

  	struct inode *inode = file_inode(vma->vm_file);

  	struct nilfs_transaction_info ti;

  	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);

  	lock_page(page);
  	if (page->mapping != inode->i_mapping ||
  	    page_offset(page) >= i_size_read(inode) || !PageUptodate(page)) {
  		unlock_page(page);

  		ret = -EFAULT;	/* make the VM retry the fault */
  		goto out;

  	}
  
  	/*
  	 * check to see if the page is mapped already (no holes)
  	 */

  	if (PageMappedToDisk(page))

  		goto mapped;

  	if (page_has_buffers(page)) {
  		struct buffer_head *bh, *head;
  		int fully_mapped = 1;
  
  		bh = head = page_buffers(page);
  		do {
  			if (!buffer_mapped(bh)) {
  				fully_mapped = 0;
  				break;
  			}
  		} while (bh = bh->b_this_page, bh != head);
  
  		if (fully_mapped) {
  			SetPageMappedToDisk(page);

  			goto mapped;
  		}
  	}
  	unlock_page(page);
  
  	/*
  	 * 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:

  	wait_for_stable_page(page);

   out:
  	sb_end_pagefault(inode->i_sb);
  	return block_page_mkwrite_return(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(struct file *file, struct vm_area_struct *vma)
  {
  	file_accessed(file);
  	vma->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		= nilfs_file_mmap,
  	.open		= generic_file_open,
  	/* .release	= nilfs_release_file, */
  	.fsync		= nilfs_sync_file,
  	.splice_read	= generic_file_splice_read,
  };

  const struct inode_operations nilfs_file_inode_operations = {

  	.setattr	= nilfs_setattr,
  	.permission     = nilfs_permission,

  	.fiemap		= nilfs_fiemap,

  };
  
  /* end of file */