path: root/fs/nilfs2/cpfile.c

/*
 * cpfile.c - NILFS checkpoint 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>.
 */

#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 "cpfile.h"


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

/* block number from the beginning of the file */
static unsigned long
nilfs_cpfile_get_blkoff(const struct inode *cpfile, __u64 cno)
{
	__u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
	do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
	return (unsigned long)tcno;
}

/* offset in block */
static unsigned long
nilfs_cpfile_get_offset(const struct inode *cpfile, __u64 cno)
{
	__u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
	return do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
}

static unsigned long
nilfs_cpfile_checkpoints_in_block(const struct inode *cpfile,
				  __u64 curr,
				  __u64 max)
{
	return min_t(__u64,
		     nilfs_cpfile_checkpoints_per_block(cpfile) -
		     nilfs_cpfile_get_offset(cpfile, curr),
		     max - curr);
}

static inline int nilfs_cpfile_is_in_first(const struct inode *cpfile,
					   __u64 cno)
{
	return nilfs_cpfile_get_blkoff(cpfile, cno) == 0;
}

static unsigned int
nilfs_cpfile_block_add_valid_checkpoints(const struct inode *cpfile,
					 struct buffer_head *bh,
					 void *kaddr,
					 unsigned int n)
{
	struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
	unsigned int count;

	count = le32_to_cpu(cp->cp_checkpoints_count) + n;
	cp->cp_checkpoints_count = cpu_to_le32(count);
	return count;
}

static unsigned int
nilfs_cpfile_block_sub_valid_checkpoints(const struct inode *cpfile,
					 struct buffer_head *bh,
					 void *kaddr,
					 unsigned int n)
{
	struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
	unsigned int count;

	WARN_ON(le32_to_cpu(cp->cp_checkpoints_count) < n);
	count = le32_to_cpu(cp->cp_checkpoints_count) - n;
	cp->cp_checkpoints_count = cpu_to_le32(count);
	return count;
}

static inline struct nilfs_cpfile_header *
nilfs_cpfile_block_get_header(const struct inode *cpfile,
			      struct buffer_head *bh,
			      void *kaddr)
{
	return kaddr + bh_offset(bh);
}

static struct nilfs_checkpoint *
nilfs_cpfile_block_get_checkpoint(const struct inode *cpfile, __u64 cno,
				  struct buffer_head *bh,
				  void *kaddr)
{
	return kaddr + bh_offset(bh) + nilfs_cpfile_get_offset(cpfile, cno) *
		NILFS_MDT(cpfile)->mi_entry_size;
}

static void nilfs_cpfile_block_init(struct inode *cpfile,
				    struct buffer_head *bh,
				    void *kaddr)
{
	struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
	size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
	int n = nilfs_cpfile_checkpoints_per_block(cpfile);

	while (n-- > 0) {
		nilfs_checkpoint_set_invalid(cp);
		cp = (void *)cp + cpsz;
	}
}

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

static inline int nilfs_cpfile_get_checkpoint_block(struct inode *cpfile,
						    __u64 cno,
						    int create,
						    struct buffer_head **bhp)
{
	return nilfs_mdt_get_block(cpfile,
				   nilfs_cpfile_get_blkoff(cpfile, cno),
				   create, nilfs_cpfile_block_init, bhp);
}

static inline int nilfs_cpfile_delete_checkpoint_block(struct inode *cpfile,
						       __u64 cno)
{
	return nilfs_mdt_delete_block(cpfile,
				      nilfs_cpfile_get_blkoff(cpfile, cno));
}

/**
 * nilfs_cpfile_get_checkpoint - get a checkpoint
 * @cpfile: inode of checkpoint file
 * @cno: checkpoint number
 * @create: create flag
 * @cpp: pointer to a checkpoint
 * @bhp: pointer