/*
   *  linux/fs/hpfs/file.c
   *
   *  Mikulas Patocka (mikulas@artax.karlin.mff.cuni.cz), 1998-1999
   *
   *  file VFS functions
   */
  
  #include "hpfs_fn.h"

  #include <linux/mpage.h>

  
  #define BLOCKS(size) (((size) + 511) >> 9)
  
  static int hpfs_file_release(struct inode *inode, struct file *file)
  {

  	hpfs_lock(inode->i_sb);

  	hpfs_write_if_changed(inode);

  	hpfs_unlock(inode->i_sb);

  	return 0;
  }

  int hpfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync)

  {

  	struct inode *inode = file->f_mapping->host;

  	int ret;
  
  	ret = filemap_write_and_wait_range(file->f_mapping, start, end);
  	if (ret)
  		return ret;

  	return sync_blockdev(inode->i_sb->s_bdev);

  }
  
  /*
   * generic_file_read often calls bmap with non-existing sector,
   * so we must ignore such errors.
   */

  static secno hpfs_bmap(struct inode *inode, unsigned file_secno, unsigned *n_secs)

  {
  	struct hpfs_inode_info *hpfs_inode = hpfs_i(inode);
  	unsigned n, disk_secno;
  	struct fnode *fnode;
  	struct buffer_head *bh;
  	if (BLOCKS(hpfs_i(inode)->mmu_private) <= file_secno) return 0;
  	n = file_secno - hpfs_inode->i_file_sec;

  	if (n < hpfs_inode->i_n_secs) {
  		*n_secs = hpfs_inode->i_n_secs - n;
  		return hpfs_inode->i_disk_sec + n;
  	}

  	if (!(fnode = hpfs_map_fnode(inode->i_sb, inode->i_ino, &bh))) return 0;
  	disk_secno = hpfs_bplus_lookup(inode->i_sb, inode, &fnode->btree, file_secno, bh);
  	if (disk_secno == -1) return 0;
  	if (hpfs_chk_sectors(inode->i_sb, disk_secno, 1, "bmap")) return 0;

  	n = file_secno - hpfs_inode->i_file_sec;
  	if (n < hpfs_inode->i_n_secs) {
  		*n_secs = hpfs_inode->i_n_secs - n;
  		return hpfs_inode->i_disk_sec + n;
  	}
  	*n_secs = 1;

  	return disk_secno;
  }

  void hpfs_truncate(struct inode *i)

  {
  	if (IS_IMMUTABLE(i)) return /*-EPERM*/;

  	hpfs_lock_assert(i->i_sb);

  	hpfs_i(i)->i_n_secs = 0;
  	i->i_blocks = 1 + ((i->i_size + 511) >> 9);
  	hpfs_i(i)->mmu_private = i->i_size;
  	hpfs_truncate_btree(i->i_sb, i->i_ino, 1, ((i->i_size + 511) >> 9));
  	hpfs_write_inode(i);
  	hpfs_i(i)->i_n_secs = 0;

  }
  
  static int hpfs_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create)
  {

  	int r;

  	secno s;

  	unsigned n_secs;

  	hpfs_lock(inode->i_sb);

  	s = hpfs_bmap(inode, iblock, &n_secs);

  	if (s) {

  		if (bh_result->b_size >> 9 < n_secs)
  			n_secs = bh_result->b_size >> 9;

  		n_secs = hpfs_search_hotfix_map_for_range(inode->i_sb, s, n_secs);
  		if (unlikely(!n_secs)) {
  			s = hpfs_search_hotfix_map(inode->i_sb, s);
  			n_secs = 1;
  		}

  		map_bh(bh_result, inode->i_sb, s);

  		bh_result->b_size = n_secs << 9;

  		goto ret_0;

  	}

  	if (!create) goto ret_0;

  	if (iblock<<9 != hpfs_i(inode)->mmu_private) {
  		BUG();

  		r = -EIO;
  		goto ret_r;

  	}
  	if ((s = hpfs_add_sector_to_btree(inode->i_sb, inode->i_ino, 1, inode->i_blocks - 1)) == -1) {
  		hpfs_truncate_btree(inode->i_sb, inode->i_ino, 1, inode->i_blocks - 1);

  		r = -ENOSPC;
  		goto ret_r;

  	}
  	inode->i_blocks++;
  	hpfs_i(inode)->mmu_private += 512;
  	set_buffer_new(bh_result);

  	map_bh(bh_result, inode->i_sb, hpfs_search_hotfix_map(inode->i_sb, s));

  	ret_0:
  	r = 0;
  	ret_r:
  	hpfs_unlock(inode->i_sb);
  	return r;

  }

  static int hpfs_readpage(struct file *file, struct page *page)
  {
  	return mpage_readpage(page, hpfs_get_block);
  }

  static int hpfs_writepage(struct page *page, struct writeback_control *wbc)
  {

  	return block_write_full_page(page, hpfs_get_block, wbc);

  }

  static int hpfs_readpages(struct file *file, struct address_space *mapping,
  			  struct list_head *pages, unsigned nr_pages)
  {
  	return mpage_readpages(mapping, pages, nr_pages, hpfs_get_block);
  }
  
  static int hpfs_writepages(struct address_space *mapping,
  			   struct writeback_control *wbc)

  {

  	return mpage_writepages(mapping, wbc, hpfs_get_block);

  }

  static void hpfs_write_failed(struct address_space *mapping, loff_t to)
  {
  	struct inode *inode = mapping->host;

  	hpfs_lock(inode->i_sb);

  	if (to > inode->i_size) {

  		truncate_pagecache(inode, inode->i_size);

  		hpfs_truncate(inode);
  	}

  
  	hpfs_unlock(inode->i_sb);

  }

  static int hpfs_write_begin(struct file *file, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned flags,
  			struct page **pagep, void **fsdata)

  {

  	int ret;

  	*pagep = NULL;

  	ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,

  				hpfs_get_block,
  				&hpfs_i(mapping->host)->mmu_private);

  	if (unlikely(ret))
  		hpfs_write_failed(mapping, pos + len);

  
  	return ret;

  }

  static int hpfs_write_end(struct file *file, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned copied,
  			struct page *pagep, void *fsdata)
  {
  	struct inode *inode = mapping->host;
  	int err;
  	err = generic_write_end(file, mapping, pos, len, copied, pagep, fsdata);
  	if (err < len)
  		hpfs_write_failed(mapping, pos + len);
  	if (!(err < 0)) {
  		/* make sure we write it on close, if not earlier */
  		hpfs_lock(inode->i_sb);
  		hpfs_i(inode)->i_dirty = 1;
  		hpfs_unlock(inode->i_sb);
  	}
  	return err;
  }

  static sector_t _hpfs_bmap(struct address_space *mapping, sector_t block)
  {

  	return generic_block_bmap(mapping, block, hpfs_get_block);

  }

  const struct address_space_operations hpfs_aops = {

  	.readpage = hpfs_readpage,
  	.writepage = hpfs_writepage,

  	.readpages = hpfs_readpages,
  	.writepages = hpfs_writepages,

  	.write_begin = hpfs_write_begin,

  	.write_end = hpfs_write_end,

  	.bmap = _hpfs_bmap
  };

  const struct file_operations hpfs_file_ops =

  {
  	.llseek		= generic_file_llseek,

  	.read_iter	= generic_file_read_iter,

  	.write_iter	= generic_file_write_iter,

  	.mmap		= generic_file_mmap,
  	.release	= hpfs_file_release,
  	.fsync		= hpfs_file_fsync,

  	.splice_read	= generic_file_splice_read,

  	.unlocked_ioctl	= hpfs_ioctl,

  };

  const struct inode_operations hpfs_file_iops =

  {

  	.setattr	= hpfs_setattr,

  };