1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
4 *
5 * This file is released under the GPL.
6 */
7
8#include "dm.h"
9#include <linux/module.h>
10#include <linux/init.h>
11#include <linux/blkdev.h>
12#include <linux/bio.h>
13#include <linux/dax.h>
14#include <linux/slab.h>
15#include <linux/device-mapper.h>
16
17#define DM_MSG_PREFIX "linear"
18
19/*
20 * Linear: maps a linear range of a device.
21 */
22struct linear_c {
23	struct dm_dev *dev;
24	sector_t start;
25};
26
27/*
28 * Construct a linear mapping: <dev_path> <offset>
29 */
30static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
31{
32	struct linear_c *lc;
33	unsigned long long tmp;
34	char dummy;
35	int ret;
36
37	if (argc != 2) {
38		ti->error = "Invalid argument count";
39		return -EINVAL;
40	}
41
42	lc = kmalloc(sizeof(*lc), GFP_KERNEL);
43	if (lc == NULL) {
44		ti->error = "Cannot allocate linear context";
45		return -ENOMEM;
46	}
47
48	ret = -EINVAL;
49	if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1 || tmp != (sector_t)tmp) {
50		ti->error = "Invalid device sector";
51		goto bad;
52	}
53	lc->start = tmp;
54
55	ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev);
56	if (ret) {
57		ti->error = "Device lookup failed";
58		goto bad;
59	}
60
61	ti->num_flush_bios = 1;
62	ti->num_discard_bios = 1;
63	ti->num_secure_erase_bios = 1;
64	ti->num_write_zeroes_bios = 1;
65	ti->private = lc;
66	return 0;
67
68bad:
69	kfree(lc);
70	return ret;
71}
72
73static void linear_dtr(struct dm_target *ti)
74{
75	struct linear_c *lc = ti->private;
76
77	dm_put_device(ti, lc->dev);
78	kfree(lc);
79}
80
81static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
82{
83	struct linear_c *lc = ti->private;
84
85	return lc->start + dm_target_offset(ti, bi_sector);
86}
87
88int linear_map(struct dm_target *ti, struct bio *bio)
89{
90	struct linear_c *lc = ti->private;
91
92	bio_set_dev(bio, lc->dev->bdev);
93	bio->bi_iter.bi_sector = linear_map_sector(ti, bio->bi_iter.bi_sector);
94
95	return DM_MAPIO_REMAPPED;
96}
97
98static void linear_status(struct dm_target *ti, status_type_t type,
99			  unsigned int status_flags, char *result, unsigned int maxlen)
100{
101	struct linear_c *lc = ti->private;
102	size_t sz = 0;
103
104	switch (type) {
105	case STATUSTYPE_INFO:
106		result[0] = '\0';
107		break;
108
109	case STATUSTYPE_TABLE:
110		DMEMIT("%s %llu", lc->dev->name, (unsigned long long)lc->start);
111		break;
112
113	case STATUSTYPE_IMA:
114		DMEMIT_TARGET_NAME_VERSION(ti->type);
115		DMEMIT(",device_name=%s,start=%llu;", lc->dev->name,
116		       (unsigned long long)lc->start);
117		break;
118	}
119}
120
121static int linear_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
122{
123	struct linear_c *lc = ti->private;
124	struct dm_dev *dev = lc->dev;
125
126	*bdev = dev->bdev;
127
128	/*
129	 * Only pass ioctls through if the device sizes match exactly.
130	 */
131	if (lc->start || ti->len != bdev_nr_sectors(dev->bdev))
132		return 1;
133	return 0;
134}
135
136#ifdef CONFIG_BLK_DEV_ZONED
137static int linear_report_zones(struct dm_target *ti,
138		struct dm_report_zones_args *args, unsigned int nr_zones)
139{
140	struct linear_c *lc = ti->private;
141
142	return dm_report_zones(lc->dev->bdev, lc->start,
143			       linear_map_sector(ti, args->next_sector),
144			       args, nr_zones);
145}
146#else
147#define linear_report_zones NULL
148#endif
149
150static int linear_iterate_devices(struct dm_target *ti,
151				  iterate_devices_callout_fn fn, void *data)
152{
153	struct linear_c *lc = ti->private;
154
155	return fn(ti, lc->dev, lc->start, ti->len, data);
156}
157
158#if IS_ENABLED(CONFIG_FS_DAX)
159static struct dax_device *linear_dax_pgoff(struct dm_target *ti, pgoff_t *pgoff)
160{
161	struct linear_c *lc = ti->private;
162	sector_t sector = linear_map_sector(ti, *pgoff << PAGE_SECTORS_SHIFT);
163
164	*pgoff = (get_start_sect(lc->dev->bdev) + sector) >> PAGE_SECTORS_SHIFT;
165	return lc->dev->dax_dev;
166}
167
168static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
169		long nr_pages, enum dax_access_mode mode, void **kaddr,
170		pfn_t *pfn)
171{
172	struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
173
174	return dax_direct_access(dax_dev, pgoff, nr_pages, mode, kaddr, pfn);
175}
176
177static int linear_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
178				      size_t nr_pages)
179{
180	struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
181
182	return dax_zero_page_range(dax_dev, pgoff, nr_pages);
183}
184
185static size_t linear_dax_recovery_write(struct dm_target *ti, pgoff_t pgoff,
186		void *addr, size_t bytes, struct iov_iter *i)
187{
188	struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
189
190	return dax_recovery_write(dax_dev, pgoff, addr, bytes, i);
191}
192
193#else
194#define linear_dax_direct_access NULL
195#define linear_dax_zero_page_range NULL
196#define linear_dax_recovery_write NULL
197#endif
198
199static struct target_type linear_target = {
200	.name   = "linear",
201	.version = {1, 4, 0},
202	.features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_NOWAIT |
203		    DM_TARGET_ZONED_HM | DM_TARGET_PASSES_CRYPTO,
204	.report_zones = linear_report_zones,
205	.module = THIS_MODULE,
206	.ctr    = linear_ctr,
207	.dtr    = linear_dtr,
208	.map    = linear_map,
209	.status = linear_status,
210	.prepare_ioctl = linear_prepare_ioctl,
211	.iterate_devices = linear_iterate_devices,
212	.direct_access = linear_dax_direct_access,
213	.dax_zero_page_range = linear_dax_zero_page_range,
214	.dax_recovery_write = linear_dax_recovery_write,
215};
216
217int __init dm_linear_init(void)
218{
219	int r = dm_register_target(&linear_target);
220
221	if (r < 0)
222		DMERR("register failed %d", r);
223
224	return r;
225}
226
227void dm_linear_exit(void)
228{
229	dm_unregister_target(&linear_target);
230}
231