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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_obj(*lc);
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->flush_bypasses_map = true;
66 ti->private = lc;
67 return 0;
68
69bad:
70 kfree(lc);
71 return ret;
72}
73
74static void linear_dtr(struct dm_target *ti)
75{
76 struct linear_c *lc = ti->private;
77
78 dm_put_device(ti, lc->dev);
79 kfree(lc);
80}
81
82static sector_t linear_map_sector(struct dm_target *ti, sector_t bi_sector)
83{
84 struct linear_c *lc = ti->private;
85
86 return lc->start + dm_target_offset(ti, bi_sector);
87}
88
89int linear_map(struct dm_target *ti, struct bio *bio)
90{
91 struct linear_c *lc = ti->private;
92
93 bio_set_dev(bio, lc->dev->bdev);
94 bio->bi_iter.bi_sector = linear_map_sector(ti, bio->bi_iter.bi_sector);
95
96 return DM_MAPIO_REMAPPED;
97}
98
99static void linear_status(struct dm_target *ti, status_type_t type,
100 unsigned int status_flags, char *result, unsigned int maxlen)
101{
102 struct linear_c *lc = ti->private;
103 size_t sz = 0;
104
105 switch (type) {
106 case STATUSTYPE_INFO:
107 result[0] = '\0';
108 break;
109
110 case STATUSTYPE_TABLE:
111 DMEMIT("%s %llu", lc->dev->name, (unsigned long long)lc->start);
112 break;
113
114 case STATUSTYPE_IMA:
115 DMEMIT_TARGET_NAME_VERSION(ti->type);
116 DMEMIT(",device_name=%s,start=%llu;", lc->dev->name,
117 (unsigned long long)lc->start);
118 break;
119 }
120}
121
122static int linear_prepare_ioctl(struct dm_target *ti, struct block_device **bdev,
123 unsigned int cmd, unsigned long arg,
124 bool *forward)
125{
126 struct linear_c *lc = 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 || ti->len != bdev_nr_sectors(dev->bdev))
135 return 1;
136 return 0;
137}
138
139#ifdef CONFIG_BLK_DEV_ZONED
140static int linear_report_zones(struct dm_target *ti,
141 struct dm_report_zones_args *args, unsigned int nr_zones)
142{
143 struct linear_c *lc = ti->private;
144
145 return dm_report_zones(lc->dev->bdev, lc->start,
146 linear_map_sector(ti, args->next_sector),
147 args, nr_zones);
148}
149#else
150#define linear_report_zones NULL
151#endif
152
153static int linear_iterate_devices(struct dm_target *ti,
154 iterate_devices_callout_fn fn, void *data)
155{
156 struct linear_c *lc = ti->private;
157
158 return fn(ti, lc->dev, lc->start, ti->len, data);
159}
160
161#if IS_ENABLED(CONFIG_FS_DAX)
162static struct dax_device *linear_dax_pgoff(struct dm_target *ti, pgoff_t *pgoff)
163{
164 struct linear_c *lc = ti->private;
165 sector_t sector = linear_map_sector(ti, *pgoff << PAGE_SECTORS_SHIFT);
166
167 *pgoff = (get_start_sect(lc->dev->bdev) + sector) >> PAGE_SECTORS_SHIFT;
168 return lc->dev->dax_dev;
169}
170
171static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
172 long nr_pages, enum dax_access_mode mode, void **kaddr,
173 unsigned long *pfn)
174{
175 struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
176
177 return dax_direct_access(dax_dev, pgoff, nr_pages, mode, kaddr, pfn);
178}
179
180static int linear_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
181 size_t nr_pages)
182{
183 struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
184
185 return dax_zero_page_range(dax_dev, pgoff, nr_pages);
186}
187
188static size_t linear_dax_recovery_write(struct dm_target *ti, pgoff_t pgoff,
189 void *addr, size_t bytes, struct iov_iter *i)
190{
191 struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
192
193 return dax_recovery_write(dax_dev, pgoff, addr, bytes, i);
194}
195
196#else
197#define linear_dax_direct_access NULL
198#define linear_dax_zero_page_range NULL
199#define linear_dax_recovery_write NULL
200#endif
201
202static struct target_type linear_target = {
203 .name = "linear",
204 .version = {1, 5, 0},
205 .features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_NOWAIT |
206 DM_TARGET_ZONED_HM | DM_TARGET_PASSES_CRYPTO |
207 DM_TARGET_ATOMIC_WRITES,
208 .report_zones = linear_report_zones,
209 .module = THIS_MODULE,
210 .ctr = linear_ctr,
211 .dtr = linear_dtr,
212 .map = linear_map,
213 .status = linear_status,
214 .prepare_ioctl = linear_prepare_ioctl,
215 .iterate_devices = linear_iterate_devices,
216 .direct_access = linear_dax_direct_access,
217 .dax_zero_page_range = linear_dax_zero_page_range,
218 .dax_recovery_write = linear_dax_recovery_write,
219};
220
221int __init dm_linear_init(void)
222{
223 int r = dm_register_target(&linear_target);
224
225 if (r < 0)
226 DMERR("register failed %d", r);
227
228 return r;
229}
230
231void dm_linear_exit(void)
232{
233 dm_unregister_target(&linear_target);
234}