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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -07008#include <linux/module.h>
9#include <linux/init.h>
10#include <linux/blkdev.h>
11#include <linux/bio.h>
12#include <linux/slab.h>
Mikulas Patocka586e80e2008-10-21 17:44:59 +010013#include <linux/device-mapper.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014
Alasdair G Kergon72d94862006-06-26 00:27:35 -070015#define DM_MSG_PREFIX "linear"
16
Linus Torvalds1da177e2005-04-16 15:20:36 -070017/*
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;
Andrew Morton4ee218c2006-03-27 01:17:48 -080031 unsigned long long tmp;
Mikulas Patocka31998ef2012-03-28 18:41:26 +010032 char dummy;
Linus Torvalds1da177e2005-04-16 15:20:36 -070033
34 if (argc != 2) {
Alasdair G Kergon72d94862006-06-26 00:27:35 -070035 ti->error = "Invalid argument count";
Linus Torvalds1da177e2005-04-16 15:20:36 -070036 return -EINVAL;
37 }
38
39 lc = kmalloc(sizeof(*lc), GFP_KERNEL);
40 if (lc == NULL) {
41 ti->error = "dm-linear: Cannot allocate linear context";
42 return -ENOMEM;
43 }
44
Mikulas Patocka31998ef2012-03-28 18:41:26 +010045 if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 ti->error = "dm-linear: Invalid device sector";
47 goto bad;
48 }
Andrew Morton4ee218c2006-03-27 01:17:48 -080049 lc->start = tmp;
Linus Torvalds1da177e2005-04-16 15:20:36 -070050
Nikanth Karthikesan8215d6e2010-03-06 02:32:27 +000051 if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 ti->error = "dm-linear: Device lookup failed";
53 goto bad;
54 }
55
Mikulas Patocka433bcac2009-06-22 10:12:22 +010056 ti->num_flush_requests = 1;
Mike Snitzer5ae89a82010-08-12 04:14:08 +010057 ti->num_discard_requests = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -070058 ti->private = lc;
59 return 0;
60
61 bad:
62 kfree(lc);
63 return -EINVAL;
64}
65
66static void linear_dtr(struct dm_target *ti)
67{
68 struct linear_c *lc = (struct linear_c *) ti->private;
69
70 dm_put_device(ti, lc->dev);
71 kfree(lc);
72}
73
Milan Broz7bc34472008-07-21 12:00:38 +010074static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
75{
76 struct linear_c *lc = ti->private;
77
Alasdair G Kergonb441a2622010-08-12 04:14:11 +010078 return lc->start + dm_target_offset(ti, bi_sector);
Milan Broz7bc34472008-07-21 12:00:38 +010079}
80
81static void linear_map_bio(struct dm_target *ti, struct bio *bio)
82{
83 struct linear_c *lc = ti->private;
84
85 bio->bi_bdev = lc->dev->bdev;
Mikulas Patocka433bcac2009-06-22 10:12:22 +010086 if (bio_sectors(bio))
87 bio->bi_sector = linear_map_sector(ti, bio->bi_sector);
Milan Broz7bc34472008-07-21 12:00:38 +010088}
89
Linus Torvalds1da177e2005-04-16 15:20:36 -070090static int linear_map(struct dm_target *ti, struct bio *bio,
91 union map_info *map_context)
92{
Milan Broz7bc34472008-07-21 12:00:38 +010093 linear_map_bio(ti, bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -070094
Kiyoshi Uedad2a7ad22006-12-08 02:41:06 -080095 return DM_MAPIO_REMAPPED;
Linus Torvalds1da177e2005-04-16 15:20:36 -070096}
97
98static int linear_status(struct dm_target *ti, status_type_t type,
Alasdair G Kergon1f4e0ff2012-07-27 15:08:16 +010099 unsigned status_flags, char *result, unsigned maxlen)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100{
101 struct linear_c *lc = (struct linear_c *) ti->private;
102
103 switch (type) {
104 case STATUSTYPE_INFO:
105 result[0] = '\0';
106 break;
107
108 case STATUSTYPE_TABLE:
Andrew Morton4ee218c2006-03-27 01:17:48 -0800109 snprintf(result, maxlen, "%s %llu", lc->dev->name,
110 (unsigned long long)lc->start);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 break;
112 }
113 return 0;
114}
115
Al Viro647b3d02007-08-28 22:15:59 -0400116static int linear_ioctl(struct dm_target *ti, unsigned int cmd,
Milan Brozab17ffa2006-10-03 01:15:18 -0700117 unsigned long arg)
118{
119 struct linear_c *lc = (struct linear_c *) ti->private;
Paolo Bonziniec8013b2012-01-12 16:01:29 +0100120 struct dm_dev *dev = lc->dev;
121 int r = 0;
122
123 /*
124 * Only pass ioctls through if the device sizes match exactly.
125 */
126 if (lc->start ||
127 ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
128 r = scsi_verify_blk_ioctl(NULL, cmd);
129
130 return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
Milan Brozab17ffa2006-10-03 01:15:18 -0700131}
132
Milan Broz7bc34472008-07-21 12:00:38 +0100133static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
134 struct bio_vec *biovec, int max_size)
135{
136 struct linear_c *lc = ti->private;
137 struct request_queue *q = bdev_get_queue(lc->dev->bdev);
138
139 if (!q->merge_bvec_fn)
140 return max_size;
141
142 bvm->bi_bdev = lc->dev->bdev;
143 bvm->bi_sector = linear_map_sector(ti, bvm->bi_sector);
144
145 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
146}
147
Mike Snitzeraf4874e2009-06-22 10:12:33 +0100148static int linear_iterate_devices(struct dm_target *ti,
149 iterate_devices_callout_fn fn, void *data)
150{
151 struct linear_c *lc = ti->private;
152
Mike Snitzer5dea2712009-07-23 20:30:42 +0100153 return fn(ti, lc->dev, lc->start, ti->len, data);
Mike Snitzeraf4874e2009-06-22 10:12:33 +0100154}
155
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156static struct target_type linear_target = {
157 .name = "linear",
Mike Snitzeraf4874e2009-06-22 10:12:33 +0100158 .version = {1, 1, 0},
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 .module = THIS_MODULE,
160 .ctr = linear_ctr,
161 .dtr = linear_dtr,
162 .map = linear_map,
163 .status = linear_status,
Milan Brozab17ffa2006-10-03 01:15:18 -0700164 .ioctl = linear_ioctl,
Milan Broz7bc34472008-07-21 12:00:38 +0100165 .merge = linear_merge,
Mike Snitzeraf4874e2009-06-22 10:12:33 +0100166 .iterate_devices = linear_iterate_devices,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167};
168
169int __init dm_linear_init(void)
170{
171 int r = dm_register_target(&linear_target);
172
173 if (r < 0)
Alasdair G Kergon72d94862006-06-26 00:27:35 -0700174 DMERR("register failed %d", r);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175
176 return r;
177}
178
179void dm_linear_exit(void)
180{
Mikulas Patocka10d3bd02009-01-06 03:04:58 +0000181 dm_unregister_target(&linear_target);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182}