[go: nahoru, domu]
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	char dummy;
33
34	if (argc != 2) {
35		ti->error = "Invalid argument count";
36		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
45	if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1) {
46		ti->error = "dm-linear: Invalid device sector";
47		goto bad;
48	}
49	lc->start = tmp;
50
51	if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev)) {
52		ti->error = "dm-linear: Device lookup failed";
53		goto bad;
54	}
55
56	ti->num_flush_bios = 1;
57	ti->num_discard_bios = 1;
58	ti->num_write_same_bios = 1;
59	ti->private = lc;
60	return 0;
61
62      bad:
63	kfree(lc);
64	return -EINVAL;
65}
66
67static void linear_dtr(struct dm_target *ti)
68{
69	struct linear_c *lc = (struct linear_c *) ti->private;
70
71	dm_put_device(ti, lc->dev);
72	kfree(lc);
73}
74
75static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
76{
77	struct linear_c *lc = ti->private;
78
79	return lc->start + dm_target_offset(ti, bi_sector);
80}
81
82static void linear_map_bio(struct dm_target *ti, struct bio *bio)
83{
84	struct linear_c *lc = ti->private;
85
86	bio->bi_bdev = lc->dev->bdev;
87	if (bio_sectors(bio))
88		bio->bi_iter.bi_sector =
89			linear_map_sector(ti, bio->bi_iter.bi_sector);
90}
91
92static int linear_map(struct dm_target *ti, struct bio *bio)
93{
94	linear_map_bio(ti, bio);
95
96	return DM_MAPIO_REMAPPED;
97}
98
99static void linear_status(struct dm_target *ti, status_type_t type,
100			  unsigned status_flags, char *result, unsigned maxlen)
101{
102	struct linear_c *lc = (struct linear_c *) ti->private;
103
104	switch (type) {
105	case STATUSTYPE_INFO:
106		result[0] = '\0';
107		break;
108
109	case STATUSTYPE_TABLE:
110		snprintf(result, maxlen, "%s %llu", lc->dev->name,
111				(unsigned long long)lc->start);
112		break;
113	}
114}
115
116static int linear_ioctl(struct dm_target *ti, unsigned int cmd,
117			unsigned long arg)
118{
119	struct linear_c *lc = (struct linear_c *) ti->private;
120	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);
131}
132
133static 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
148static 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
153	return fn(ti, lc->dev, lc->start, ti->len, data);
154}
155
156static struct target_type linear_target = {
157	.name   = "linear",
158	.version = {1, 2, 1},
159	.module = THIS_MODULE,
160	.ctr    = linear_ctr,
161	.dtr    = linear_dtr,
162	.map    = linear_map,
163	.status = linear_status,
164	.ioctl  = linear_ioctl,
165	.merge  = linear_merge,
166	.iterate_devices = linear_iterate_devices,
167};
168
169int __init dm_linear_init(void)
170{
171	int r = dm_register_target(&linear_target);
172
173	if (r < 0)
174		DMERR("register failed %d", r);
175
176	return r;
177}
178
179void dm_linear_exit(void)
180{
181	dm_unregister_target(&linear_target);
182}
183