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/*
* linux/fs/ext2/xip.c
*
* Copyright (C) 2005 IBM Corporation
* Author: Carsten Otte (cotte@de.ibm.com)
*/
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/genhd.h>
#include <linux/buffer_head.h>
#include <linux/ext2_fs_sb.h>
#include <linux/ext2_fs.h>
#include "ext2.h"
#include "xip.h"
static inline int
__inode_direct_access(struct inode *inode, sector_t sector,
unsigned long *data)
{
BUG_ON(!inode->i_sb->s_bdev->bd_disk->fops->direct_access);
return inode->i_sb->s_bdev->bd_disk->fops
->direct_access(inode->i_sb->s_bdev,sector,data);
}
static inline int
__ext2_get_sector(struct inode *inode, sector_t offset, int create,
sector_t *result)
{
struct buffer_head tmp;
int rc;
memset(&tmp, 0, sizeof(struct buffer_head));
rc = ext2_get_block(inode, offset/ (PAGE_SIZE/512), &tmp,
create);
*result = tmp.b_blocknr;
/* did we get a sparse block (hole in the file)? */
if (!(*result)) {
BUG_ON(create);
rc = -ENODATA;
}
return rc;
}
int
ext2_clear_xip_target(struct inode *inode, int block)
{
sector_t sector = block * (PAGE_SIZE/512);
unsigned long data;
int rc;
rc = __inode_direct_access(inode, sector, &data);
if (!rc)
clear_page((void*)data);
return rc;
}
void ext2_xip_verify_sb(struct super_block *sb)
{
struct ext2_sb_info *sbi = EXT2_SB(sb);
if ((sbi->s_mount_opt & EXT2_MOUNT_XIP) &&
!sb->s_bdev->bd_disk->fops->direct_access) {
sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);
ext2_warning(sb, __FUNCTION__,
"ignoring xip option - not supported by bdev");
}
}
struct page *
ext2_get_xip_page(struct address_space *mapping, sector_t offset,
int create)
{
int rc;
unsigned long data;
sector_t sector;
/* first, retrieve the sector number */
rc = __ext2_get_sector(mapping->host, offset, create, §or);
if (rc)
goto error;
/* retrieve address of the target data */
rc = __inode_direct_access
(mapping->host, sector * (PAGE_SIZE/512), &data);
if (!rc)
return virt_to_page(data);
error:
return ERR_PTR(rc);
}