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 */
20 struct linear_c {
21 struct dm_dev *dev;
22 sector_t start;
23 };
24
25 /*
26 * Construct a linear mapping: <dev_path> <offset>
27 */
dm_linear_ctr(struct dm_target * ti,unsigned int argc,char ** argv)28 int dm_linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
29 {
30 struct linear_c *lc;
31 unsigned long long tmp;
32 char dummy;
33 int ret;
34
35 if (argc != 2) {
36 ti->error = "Invalid argument count";
37 return -EINVAL;
38 }
39
40 lc = kmalloc(sizeof(*lc), GFP_KERNEL);
41 if (lc == NULL) {
42 ti->error = "Cannot allocate linear context";
43 return -ENOMEM;
44 }
45
46 ret = -EINVAL;
47 if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1) {
48 ti->error = "Invalid device sector";
49 goto bad;
50 }
51 lc->start = tmp;
52
53 ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev);
54 if (ret) {
55 ti->error = "Device lookup failed";
56 goto bad;
57 }
58
59 ti->num_flush_bios = 1;
60 ti->num_discard_bios = 1;
61 ti->num_write_same_bios = 1;
62 ti->private = lc;
63 return 0;
64
65 bad:
66 kfree(lc);
67 return ret;
68 }
69 EXPORT_SYMBOL_GPL(dm_linear_ctr);
70
dm_linear_dtr(struct dm_target * ti)71 void dm_linear_dtr(struct dm_target *ti)
72 {
73 struct linear_c *lc = (struct linear_c *) ti->private;
74
75 dm_put_device(ti, lc->dev);
76 kfree(lc);
77 }
78 EXPORT_SYMBOL_GPL(dm_linear_dtr);
79
linear_map_sector(struct dm_target * ti,sector_t bi_sector)80 static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
81 {
82 struct linear_c *lc = ti->private;
83
84 return lc->start + dm_target_offset(ti, bi_sector);
85 }
86
linear_map_bio(struct dm_target * ti,struct bio * bio)87 static void linear_map_bio(struct dm_target *ti, struct bio *bio)
88 {
89 struct linear_c *lc = ti->private;
90
91 bio->bi_bdev = lc->dev->bdev;
92 if (bio_sectors(bio))
93 bio->bi_iter.bi_sector =
94 linear_map_sector(ti, bio->bi_iter.bi_sector);
95 }
96
dm_linear_map(struct dm_target * ti,struct bio * bio)97 int dm_linear_map(struct dm_target *ti, struct bio *bio)
98 {
99 linear_map_bio(ti, bio);
100
101 return DM_MAPIO_REMAPPED;
102 }
103 EXPORT_SYMBOL_GPL(dm_linear_map);
104
dm_linear_status(struct dm_target * ti,status_type_t type,unsigned status_flags,char * result,unsigned maxlen)105 void dm_linear_status(struct dm_target *ti, status_type_t type,
106 unsigned status_flags, char *result, unsigned maxlen)
107 {
108 struct linear_c *lc = (struct linear_c *) ti->private;
109
110 switch (type) {
111 case STATUSTYPE_INFO:
112 result[0] = '\0';
113 break;
114
115 case STATUSTYPE_TABLE:
116 snprintf(result, maxlen, "%s %llu", lc->dev->name,
117 (unsigned long long)lc->start);
118 break;
119 }
120 }
121 EXPORT_SYMBOL_GPL(dm_linear_status);
122
dm_linear_prepare_ioctl(struct dm_target * ti,struct block_device ** bdev,fmode_t * mode)123 int dm_linear_prepare_ioctl(struct dm_target *ti,
124 struct block_device **bdev, fmode_t *mode)
125 {
126 struct linear_c *lc = (struct linear_c *) ti->private;
127 struct dm_dev *dev = lc->dev;
128
129 *bdev = dev->bdev;
130
131 /*
132 * Only pass ioctls through if the device sizes match exactly.
133 */
134 if (lc->start ||
135 ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
136 return 1;
137 return 0;
138 }
139 EXPORT_SYMBOL_GPL(dm_linear_prepare_ioctl);
140
dm_linear_iterate_devices(struct dm_target * ti,iterate_devices_callout_fn fn,void * data)141 int dm_linear_iterate_devices(struct dm_target *ti,
142 iterate_devices_callout_fn fn, void *data)
143 {
144 struct linear_c *lc = ti->private;
145
146 return fn(ti, lc->dev, lc->start, ti->len, data);
147 }
148 EXPORT_SYMBOL_GPL(dm_linear_iterate_devices);
149
150 static struct target_type linear_target = {
151 .name = "linear",
152 .version = {1, 2, 1},
153 .module = THIS_MODULE,
154 .ctr = dm_linear_ctr,
155 .dtr = dm_linear_dtr,
156 .map = dm_linear_map,
157 .status = dm_linear_status,
158 .prepare_ioctl = dm_linear_prepare_ioctl,
159 .iterate_devices = dm_linear_iterate_devices,
160 };
161
dm_linear_init(void)162 int __init dm_linear_init(void)
163 {
164 int r = dm_register_target(&linear_target);
165
166 if (r < 0)
167 DMERR("register failed %d", r);
168
169 return r;
170 }
171
dm_linear_exit(void)172 void dm_linear_exit(void)
173 {
174 dm_unregister_target(&linear_target);
175 }
176