path: root/fs/nilfs2/sufile.c

/*
 * sufile.c - NILFS segment usage file.
 *
 * 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>.
 * Revised by Ryusuke Konishi <ryusuke@osrg.net>.
 */

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/buffer_head.h>
#include <linux/errno.h>
#include <linux/nilfs2_fs.h>
#include "mdt.h"
#include "sufile.h"

/**
 * struct nilfs_sufile_info - on-memory private data of sufile
 * @mi: on-memory private data of metadata file
 * @ncleansegs: number of clean segments
 * @allocmin: lower limit of allocatable segment range
 * @allocmax: upper limit of allocatable segment range
 */
struct nilfs_sufile_info {
	struct nilfs_mdt_info mi;
	unsigned long ncleansegs;/* number of clean segments */
	__u64 allocmin;		/* lower limit of allocatable segment range */
	__u64 allocmax;		/* upper limit of allocatable segment range */
};

static inline struct nilfs_sufile_info *NILFS_SUI(struct inode *sufile)
{
	return (struct nilfs_sufile_info *)NILFS_MDT(sufile);
}

static inline unsigned long
nilfs_sufile_segment_usages_per_block(const struct inode *sufile)
{
	return NILFS_MDT(sufile)->mi_entries_per_block;
}

static unsigned long
nilfs_sufile_get_blkoff(const struct inode *sufile, __u64 segnum)
{
	__u64 t = segnum + NILFS_MDT(sufile)->mi_first_entry_offset;
	do_div(t, nilfs_sufile_segment_usages_per_block(sufile));
	return (unsigned long)t;
}

static unsigned long
nilfs_sufile_get_offset(const struct inode *sufile, __u64 segnum)
{
	__u64 t = segnum + NILFS_MDT(sufile)->mi_first_entry_offset;
	return do_div(t, nilfs_sufile_segment_usages_per_block(sufile));
}

static unsigned long
nilfs_sufile_segment_usages_in_block(const struct inode *sufile, __u64 curr,
				     __u64 max)
{
	return min_t(unsigned long,
		     nilfs_sufile_segment_usages_per_block(sufile) -
		     nilfs_sufile_get_offset(sufile, curr),
		     max - curr + 1);
}

static struct nilfs_segment_usage *
nilfs_sufile_block_get_segment_usage(const struct inode *sufile, __u64 segnum,
				     struct buffer_head *bh, void *kaddr)
{
	return kaddr + bh_offset(bh) +
		nilfs_sufile_get_offset(sufile, segnum) *
		NILFS_MDT(sufile)->mi_entry_size;
}

static inline int nilfs_sufile_get_header_block(struct inode *sufile,
						struct buffer_head **bhp)
{
	return nilfs_mdt_get_block(sufile, 0, 0, NULL, bhp);
}

static inline int
nilfs_sufile_get_segment_usage_block(struct inode *sufile, __u64 segnum,
				     int create, struct buffer_head **bhp)
{
	return nilfs_mdt_get_block(sufile,
				   nilfs_sufile_get_blkoff(sufile, segnum),
				   create, NULL, bhp);
}

static int nilfs_sufile_delete_segment_usage_block(struct inode *sufile,
						   __u64 segnum)
{
	return nilfs_mdt_