path: root/fs/nilfs2/cpfile.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * NILFS checkpoint file.
 *
 * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
 *
 * Written by Koji Sato.
 */

#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/buffer_head.h>
#include <linux/errno.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;

	tcno = div64_ul(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 __u64 nilfs_cpfile_first_checkpoint_in_block(const struct inode *cpfile,
						    unsigned long blkoff)
{
	return (__u64)nilfs_cpfile_checkpoints_per_block(cpfile) * blkoff
		+ 1 - NILFS_MDT(cpfile)->mi_first_entry_offset;
}

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,
					 unsigned int n)
{
	struct nilfs_checkpoint *cp;
	unsigned int count;

	cp = kmap_local_folio(bh->b_folio,
			      offset_in_folio(bh->b_folio, bh->b_data));
	count = le32_to_cpu(cp->cp_checkpoints_count) + n;
	cp->cp_checkpoints_count = cpu_to_le32(count);
	kunmap_local(cp);
	return count;
}

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

	cp = kmap_local_folio(bh->b_folio,
			      offset_in_folio(bh->b_folio, bh->b_data));
	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);
	kunmap_local(cp);
	return count;
}

static void nilfs_cpfile_block_init(struct inode *cpfile,
				    struct buffer_head *bh,
				    void *from)
{
	struct nilfs_checkpoint *cp = from;
	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;
	}
}

/**
 * nilfs_cpfile_checkpoint_offset - calculate the byte offset of a checkpoint
 *                                  entry in the folio containing it
 * @cpfile: checkpoint file inode
 * @cno:    checkpoint number
 * @bh:     buffer head of block containing checkpoint indexed by @cno
 *
 * Return: Byte offset in the folio of the checkpoint specified by @cno.
 */
static size_t nilfs_cpfile_checkpoint_offset(const struct inode *cpfile,
					     __u64 cno,
					     struct buffer_head *bh)
{
	return offset_in_folio(bh->b_folio, bh->b_data) +
		nilfs_cpfile_get_offset(cpfile, cno) *
		NILFS_MDT(cpfile)->mi_entry_size;
}

/**
 * nilfs_cpfile_cp_snapshot_list_offset - calculate the byte offset of a
 *                                        checkpoint snapshot list in the folio
 *                                        containing it
 * @cpfile: checkpoint file inode
 * @cno:    checkpoint number
 * @bh:     buffer head of block containing checkpoint indexed by @cno
 *
 * Return: Byte offset in the folio of the checkpoint snapshot list specified
 *         by @cno.
 */
static size_t nilfs_cpfile_cp_snapshot_list_offset(const struct inode *<