tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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], dm_table_get_mode(ti->table), &lc->dev)) {
51 ti->error = "dm-linear: Device lookup failed";
52 goto bad;
53 }
54
55 ti->num_flush_requests = 1;
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 if (bio_sectors(bio))
85 bio->bi_sector = linear_map_sector(ti, bio->bi_sector);
86}
87
88static int linear_map(struct dm_target *ti, struct bio *bio,
89 union map_info *map_context)
90{
91 linear_map_bio(ti, bio);
92
93 return DM_MAPIO_REMAPPED;
94}
95
96static int linear_status(struct dm_target *ti, status_type_t type,
97 char *result, unsigned int maxlen)
98{
99 struct linear_c *lc = (struct linear_c *) ti->private;
100
101 switch (type) {
102 case STATUSTYPE_INFO:
103 result[0] = '\0';
104 break;
105
106 case STATUSTYPE_TABLE:
107 snprintf(result, maxlen, "%s %llu", lc->dev->name,
108 (unsigned long long)lc->start);
109 break;
110 }
111 return 0;
112}
113
114static int linear_ioctl(struct dm_target *ti, unsigned int cmd,
115 unsigned long arg)
116{
117 struct linear_c *lc = (struct linear_c *) ti->private;
118 return __blkdev_driver_ioctl(lc->dev->bdev, lc->dev->mode, cmd, arg);
119}
120
121static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
122 struct bio_vec *biovec, int max_size)
123{
124 struct linear_c *lc = ti->private;
125 struct request_queue *q = bdev_get_queue(lc->dev->bdev);
126
127 if (!q->merge_bvec_fn)
128 return max_size;
129
130 bvm->bi_bdev = lc->dev->bdev;
131 bvm->bi_sector = linear_map_sector(ti, bvm->bi_sector);
132
133 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
134}
135
136static int linear_iterate_devices(struct dm_target *ti,
137 iterate_devices_callout_fn fn, void *data)
138{
139 struct linear_c *lc = ti->private;
140
141 return fn(ti, lc->dev, lc->start, ti->len, data);
142}
143
144static struct target_type linear_target = {
145 .name = "linear",
146 .version = {1, 1, 0},
147 .module = THIS_MODULE,
148 .ctr = linear_ctr,
149 .dtr = linear_dtr,
150 .map = linear_map,
151 .status = linear_status,
152 .ioctl = linear_ioctl,
153 .merge = linear_merge,
154 .iterate_devices = linear_iterate_devices,
155};
156
157int __init dm_linear_init(void)
158{
159 int r = dm_register_target(&linear_target);
160
161 if (r < 0)
162 DMERR("register failed %d", r);
163
164 return r;
165}
166
167void dm_linear_exit(void)
168{
169 dm_unregister_target(&linear_target);
170}