aboutsummaryrefslogtreecommitdiff
path: root/drivers/md/dm-linear.c
blob: 2a6bad451f8660bfb9783ad90f0b762328a974c1 (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
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
/*
 * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
 *
 * This file is released under the GPL.
 */

#include "dm.h"

#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/slab.h>

#define DM_MSG_PREFIX "linear"

/*
 * Linear: maps a linear range of a device.
 */
struct linear_c {
	struct dm_dev *dev;
	sector_t start;
};

/*
 * Construct a linear mapping: <dev_path> <offset>
 */
static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
	struct linear_c *lc;
	unsigned long long tmp;

	if (argc != 2) {
		ti->error = "Invalid argument count";
		return -EINVAL;
	}

	lc = kmalloc(sizeof(*lc), GFP_KERNEL);
	if (lc == NULL) {
		ti->error = "dm-linear: Cannot allocate linear context";
		return -ENOMEM;
	}

	if (sscanf(argv[1], "%llu", &tmp) != 1) {
		ti->error = "dm-linear: Invalid device sector";
		goto bad;
	}
	lc->start = tmp;

	if (dm_get_device(ti, argv[0], lc->start, ti->len,
			  dm_table_get_mode(ti->table), &lc->dev)) {
		ti->error = "dm-linear: Device lookup failed";
		goto bad;
	}

	ti->private = lc;
	return 0;

      bad:
	kfree(lc);
	return -EINVAL;
}

static void linear_dtr(struct dm_target *ti)
{
	struct linear_c *lc = (struct linear_c *) ti->private;

	dm_put_device(ti, lc->dev);
	kfree(lc);
}

static int linear_map(struct dm_target *ti, struct bio *bio,
		      union map_info *map_context)
{
	struct linear_c *lc = (struct linear_c *) ti->private;

	bio->bi_bdev = lc->dev->bdev;
	bio->bi_sector = lc->start + (bio->bi_sector - ti->begin);

	return 1;
}

static int linear_status(struct dm_target *ti, status_type_t type,
			 char *result, unsigned int maxlen)
{
	struct linear_c *lc = (struct linear_c *) ti->private;

	switch (type) {
	case STATUSTYPE_INFO:
		result[0] = '\0';
		break;

	case STATUSTYPE_TABLE:
		snprintf(result, maxlen, "%s %llu", lc->dev->name,
				(unsigned long long)lc->start);
		break;
	}
	return 0;
}

static int linear_ioctl(struct dm_target *ti, struct inode *inode,
			struct file *filp, unsigned int cmd,
			unsigned long arg)
{
	struct linear_c *lc = (struct linear_c *) ti->private;
	struct block_device *bdev = lc->dev->bdev;

	return blkdev_driver_ioctl(bdev->bd_inode, filp, bdev->bd_disk, cmd, arg);
}

static struct target_type linear_target = {
	.name   = "linear",
	.version= {1, 0, 2},
	.module = THIS_MODULE,
	.ctr    = linear_ctr,
	.dtr    = linear_dtr,
	.map    = linear_map,
	.status = linear_status,
	.ioctl  = linear_ioctl,
};

int __init dm_linear_init(void)
{
	int r = dm_register_target(&linear_target);

	if (r < 0)
		DMERR("register failed %d", r);

	return r;
}

void dm_linear_exit(void)
{
	int r = dm_unregister_target(&linear_target);

	if (r < 0)
		DMERR("unregister failed %d", r);
}