Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/*
2 * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm.h"
8#include <linux/module.h>
9#include <linux/init.h>
10#include <linux/blkdev.h>
11#include <linux/bio.h>
12#include <linux/slab.h>
13#include <linux/device-mapper.h>
14
15#define DM_MSG_PREFIX "linear"
16
17/*
18 * Linear: maps a linear range of a device.
19 */
20struct linear_c {
21 struct dm_dev *dev;
22 sector_t start;
23};
24
25/*
26 * Construct a linear mapping: <dev_path> <offset>
27 */
28static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
29{
30 struct linear_c *lc;
31 unsigned long long tmp;
32
33 if (argc != 2) {
34 ti->error = "Invalid argument count";
35 return -EINVAL;
36 }
37
38 lc = kmalloc(sizeof(*lc), GFP_KERNEL);
39 if (lc == NULL) {
40 ti->error = "dm-linear: Cannot allocate linear context";
41 return -ENOMEM;
42 }
43
44 if (sscanf(argv[1], "%llu", &tmp) != 1) {
45 ti->error = "dm-linear: Invalid device sector";
46 goto bad;
47 }
48 lc->start = tmp;
49
50 if (dm_get_device(ti, argv[0], lc->start, ti->len,
51 dm_table_get_mode(ti->table), &lc->dev)) {
52 ti->error = "dm-linear: Device lookup failed";
53 goto bad;
54 }
55
56 ti->private = lc;
57 return 0;
58
59 bad:
60 kfree(lc);
61 return -EINVAL;
62}
63
64static void linear_dtr(struct dm_target *ti)
65{
66 struct linear_c *lc = (struct linear_c *) ti->private;
67
68 dm_put_device(ti, lc->dev);
69 kfree(lc);
70}
71
72static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
73{
74 struct linear_c *lc = ti->private;
75
76 return lc->start + (bi_sector - ti->begin);
77}
78
79static void linear_map_bio(struct dm_target *ti, struct bio *bio)
80{
81 struct linear_c *lc = ti->private;
82
83 bio->bi_bdev = lc->dev->bdev;
84 bio->bi_sector = linear_map_sector(ti, bio->bi_sector);
85}
86
87static int linear_map(struct dm_target *ti, struct bio *bio,
88 union map_info *map_context)
89{
90 linear_map_bio(ti, bio);
91
92 return DM_MAPIO_REMAPPED;
93}
94
95static int linear_status(struct dm_target *ti, status_type_t type,
96 char *result, unsigned int maxlen)
97{
98 struct linear_c *lc = (struct linear_c *) ti->private;
99
100 switch (type) {
101 case STATUSTYPE_INFO:
102 result[0] = '\0';
103 break;
104
105 case STATUSTYPE_TABLE:
106 snprintf(result, maxlen, "%s %llu", lc->dev->name,
107 (unsigned long long)lc->start);
108 break;
109 }
110 return 0;
111}
112
113static int linear_ioctl(struct dm_target *ti, unsigned int cmd,
114 unsigned long arg)
115{
116 struct linear_c *lc = (struct linear_c *) ti->private;
117 return __blkdev_driver_ioctl(lc->dev->bdev, lc->dev->mode, cmd, arg);
118}
119
120static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
121 struct bio_vec *biovec, int max_size)
122{
123 struct linear_c *lc = ti->private;
124 struct request_queue *q = bdev_get_queue(lc->dev->bdev);
125
126 if (!q->merge_bvec_fn)
127 return max_size;
128
129 bvm->bi_bdev = lc->dev->bdev;
130 bvm->bi_sector = linear_map_sector(ti, bvm->bi_sector);
131
132 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
133}
134
135static struct target_type linear_target = {
136 .name = "linear",
137 .version= {1, 0, 3},
138 .module = THIS_MODULE,
139 .ctr = linear_ctr,
140 .dtr = linear_dtr,
141 .map = linear_map,
142 .status = linear_status,
143 .ioctl = linear_ioctl,
144 .merge = linear_merge,
145};
146
147int __init dm_linear_init(void)
148{
149 int r = dm_register_target(&linear_target);
150
151 if (r < 0)
152 DMERR("register failed %d", r);
153
154 return r;
155}
156
157void dm_linear_exit(void)
158{
159 dm_unregister_target(&linear_target);
160}