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/dax.h>
13#include <linux/slab.h>
14#include <linux/device-mapper.h>
15
16#define DM_MSG_PREFIX "linear"
17
18/*
19 * Linear: maps a linear range of a device.
20 */
21struct linear_c {
22 struct dm_dev *dev;
23 sector_t start;
24};
25
26/*
27 * Construct a linear mapping: <dev_path> <offset>
28 */
29static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
30{
31 struct linear_c *lc;
32 unsigned long long tmp;
33 char dummy;
34 int ret;
35
36 if (argc != 2) {
37 ti->error = "Invalid argument count";
38 return -EINVAL;
39 }
40
41 lc = kmalloc(sizeof(*lc), GFP_KERNEL);
42 if (lc == NULL) {
43 ti->error = "Cannot allocate linear context";
44 return -ENOMEM;
45 }
46
47 ret = -EINVAL;
48 if (sscanf(argv[1], "%llu%c", &tmp, &dummy) != 1 || tmp != (sector_t)tmp) {
49 ti->error = "Invalid device sector";
50 goto bad;
51 }
52 lc->start = tmp;
53
54 ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &lc->dev);
55 if (ret) {
56 ti->error = "Device lookup failed";
57 goto bad;
58 }
59
60 ti->num_flush_bios = 1;
61 ti->num_discard_bios = 1;
62 ti->num_secure_erase_bios = 1;
63 ti->num_write_same_bios = 1;
64 ti->num_write_zeroes_bios = 1;
65 ti->private = lc;
66 return 0;
67
68 bad:
69 kfree(lc);
70 return ret;
71}
72
73static void linear_dtr(struct dm_target *ti)
74{
75 struct linear_c *lc = (struct linear_c *) 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
88static void linear_map_bio(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 if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET)
94 bio->bi_iter.bi_sector =
95 linear_map_sector(ti, bio->bi_iter.bi_sector);
96}
97
98static int linear_map(struct dm_target *ti, struct bio *bio)
99{
100 linear_map_bio(ti, bio);
101
102 return DM_MAPIO_REMAPPED;
103}
104
105static void 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
122static int linear_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
123{
124 struct linear_c *lc = (struct linear_c *) ti->private;
125 struct dm_dev *dev = lc->dev;
126
127 *bdev = dev->bdev;
128
129 /*
130 * Only pass ioctls through if the device sizes match exactly.
131 */
132 if (lc->start ||
133 ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
134 return 1;
135 return 0;
136}
137
138#ifdef CONFIG_BLK_DEV_ZONED
139static int linear_report_zones(struct dm_target *ti, sector_t sector,
140 struct blk_zone *zones, unsigned int *nr_zones,
141 gfp_t gfp_mask)
142{
143 struct linear_c *lc = (struct linear_c *) ti->private;
144 int ret;
145
146 /* Do report and remap it */
147 ret = blkdev_report_zones(lc->dev->bdev, linear_map_sector(ti, sector),
148 zones, nr_zones, gfp_mask);
149 if (ret != 0)
150 return ret;
151
152 if (*nr_zones)
153 dm_remap_zone_report(ti, lc->start, zones, nr_zones);
154 return 0;
155}
156#endif
157
158static int linear_iterate_devices(struct dm_target *ti,
159 iterate_devices_callout_fn fn, void *data)
160{
161 struct linear_c *lc = ti->private;
162
163 return fn(ti, lc->dev, lc->start, ti->len, data);
164}
165
166#if IS_ENABLED(CONFIG_DAX_DRIVER)
167static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
168 long nr_pages, void **kaddr, pfn_t *pfn)
169{
170 long ret;
171 struct linear_c *lc = ti->private;
172 struct block_device *bdev = lc->dev->bdev;
173 struct dax_device *dax_dev = lc->dev->dax_dev;
174 sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
175
176 dev_sector = linear_map_sector(ti, sector);
177 ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff);
178 if (ret)
179 return ret;
180 return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
181}
182
183static size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
184 void *addr, size_t bytes, struct iov_iter *i)
185{
186 struct linear_c *lc = ti->private;
187 struct block_device *bdev = lc->dev->bdev;
188 struct dax_device *dax_dev = lc->dev->dax_dev;
189 sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
190
191 dev_sector = linear_map_sector(ti, sector);
192 if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
193 return 0;
194 return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
195}
196
197static size_t linear_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
198 void *addr, size_t bytes, struct iov_iter *i)
199{
200 struct linear_c *lc = ti->private;
201 struct block_device *bdev = lc->dev->bdev;
202 struct dax_device *dax_dev = lc->dev->dax_dev;
203 sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
204
205 dev_sector = linear_map_sector(ti, sector);
206 if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
207 return 0;
208 return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
209}
210
211#else
212#define linear_dax_direct_access NULL
213#define linear_dax_copy_from_iter NULL
214#define linear_dax_copy_to_iter NULL
215#endif
216
217static struct target_type linear_target = {
218 .name = "linear",
219 .version = {1, 4, 0},
220#ifdef CONFIG_BLK_DEV_ZONED
221 .features = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_ZONED_HM,
222 .report_zones = linear_report_zones,
223#else
224 .features = DM_TARGET_PASSES_INTEGRITY,
225#endif
226 .module = THIS_MODULE,
227 .ctr = linear_ctr,
228 .dtr = linear_dtr,
229 .map = linear_map,
230 .status = linear_status,
231 .prepare_ioctl = linear_prepare_ioctl,
232 .iterate_devices = linear_iterate_devices,
233 .direct_access = linear_dax_direct_access,
234 .dax_copy_from_iter = linear_dax_copy_from_iter,
235 .dax_copy_to_iter = linear_dax_copy_to_iter,
236};
237
238int __init dm_linear_init(void)
239{
240 int r = dm_register_target(&linear_target);
241
242 if (r < 0)
243 DMERR("register failed %d", r);
244
245 return r;
246}
247
248void dm_linear_exit(void)
249{
250 dm_unregister_target(&linear_target);
251}
252