linux/fs/nilfs2/direct.h
Ryusuke Konishi 3033342a0b nilfs2: remove useless b_low and b_high fields from nilfs_bmap struct
This will cut off 16 bytes from the nilfs_bmap struct which is
embedded in the on-memory inode of nilfs.

The b_high field was never used, and the b_low field stores a constant
value which can be determined by whether the inode uses btree for
block mapping or not.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
2009-06-10 23:41:10 +09:00

79 lines
2.1 KiB
C

/*
* direct.h - NILFS direct block pointer.
*
* Copyright (C) 2006-2008 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 Koji Sato <koji@osrg.net>.
*/
#ifndef _NILFS_DIRECT_H
#define _NILFS_DIRECT_H
#include <linux/types.h>
#include <linux/buffer_head.h>
#include "bmap.h"
struct nilfs_direct;
/**
* struct nilfs_direct_operations - direct mapping operation table
*/
struct nilfs_direct_operations {
__u64 (*dop_find_target)(const struct nilfs_direct *, __u64);
void (*dop_set_target)(struct nilfs_direct *, __u64, __u64);
int (*dop_propagate)(struct nilfs_direct *, struct buffer_head *);
int (*dop_assign)(struct nilfs_direct *, __u64, __u64,
struct buffer_head **, sector_t,
union nilfs_binfo *);
};
/**
* struct nilfs_direct_node - direct node
* @dn_flags: flags
* @dn_pad: padding
*/
struct nilfs_direct_node {
__u8 dn_flags;
__u8 pad[7];
};
/**
* struct nilfs_direct - direct mapping
* @d_bmap: bmap structure
* @d_ops: direct mapping operation table
*/
struct nilfs_direct {
struct nilfs_bmap d_bmap;
/* direct-mapping-specific members */
const struct nilfs_direct_operations *d_ops;
};
#define NILFS_DIRECT_NBLOCKS (NILFS_BMAP_SIZE / sizeof(__le64) - 1)
#define NILFS_DIRECT_KEY_MIN 0
#define NILFS_DIRECT_KEY_MAX (NILFS_DIRECT_NBLOCKS - 1)
int nilfs_direct_init(struct nilfs_bmap *);
int nilfs_direct_delete_and_convert(struct nilfs_bmap *, __u64, __u64 *,
__u64 *, int);
#endif /* _NILFS_DIRECT_H */