aboutsummaryrefslogtreecommitdiff
path: root/fs/ext2/xip.c
blob: 233f7fdbe31d7d323952d0389baf97182d2e6536 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
/*
 *  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 block,
		      void **kaddr, unsigned long *pfn)
{
	struct block_device *bdev = inode->i_sb->s_bdev;
	struct block_device_operations *ops = bdev->bd_disk->fops;
	sector_t sector;

	sector = block * (PAGE_SIZE / 512); /* ext2 block to bdev sector */

	BUG_ON(!ops->direct_access);
	return ops->direct_access(bdev, sector, kaddr, pfn);
}

static inline int
__ext2_get_block(struct inode *inode, pgoff_t pgoff, int create,
		   sector_t *result)
{
	struct buffer_head tmp;
	int rc;

	memset(&tmp, 0, sizeof(struct buffer_head));
	rc = ext2_get_block(inode, pgoff, &tmp, create);
	*result = tmp.b_blocknr;

	/* did we get a sparse block (hole in the file)? */
	if (!tmp.b_blocknr && !rc) {
		BUG_ON(create);
		rc = -ENODATA;
	}

	return rc;
}

int
ext2_clear_xip_target(struct inode *inode, sector_t block)
{
	void *kaddr;
	unsigned long pfn;
	int rc;

	rc = __inode_direct_access(inode, block, &kaddr, &pfn);
	if (!rc)
		clear_page(kaddr);
	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");
	}
}

int ext2_get_xip_mem(struct address_space *mapping, pgoff_t pgoff, int create,
				void **kmem, unsigned long *pfn)
{
	int rc;
	sector_t block;

	/* first, retrieve the sector number */
	rc = __ext2_get_block(mapping->host, pgoff, create, &block);
	if (rc)
		return rc;

	/* retrieve address of the target data */
	rc = __inode_direct_access(mapping->host, block, kmem, pfn);
	return rc;
}