1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2001 Sistina Software (UK) Limited
4 *
5 * This file is released under the GPL.
6 */
7
8#include "dm-core.h"
9
10#include <linux/module.h>
11#include <linux/init.h>
12#include <linux/kmod.h>
13#include <linux/bio.h>
14#include <linux/dax.h>
15
16#define DM_MSG_PREFIX "target"
17
18static LIST_HEAD(_targets);
19static DECLARE_RWSEM(_lock);
20
21static inline struct target_type *__find_target_type(const char *name)
22{
23 struct target_type *tt;
24
25 list_for_each_entry(tt, &_targets, list)
26 if (!strcmp(name, tt->name))
27 return tt;
28
29 return NULL;
30}
31
32static struct target_type *get_target_type(const char *name)
33{
34 struct target_type *tt;
35
36 down_read(sem: &_lock);
37
38 tt = __find_target_type(name);
39 if (tt && !try_module_get(module: tt->module))
40 tt = NULL;
41
42 up_read(sem: &_lock);
43 return tt;
44}
45
46static void load_module(const char *name)
47{
48 request_module("dm-%s", name);
49}
50
51struct target_type *dm_get_target_type(const char *name)
52{
53 struct target_type *tt = get_target_type(name);
54
55 if (!tt) {
56 load_module(name);
57 tt = get_target_type(name);
58 }
59
60 return tt;
61}
62
63void dm_put_target_type(struct target_type *tt)
64{
65 down_read(sem: &_lock);
66 module_put(module: tt->module);
67 up_read(sem: &_lock);
68}
69
70int dm_target_iterate(void (*iter_func)(struct target_type *tt,
71 void *param), void *param)
72{
73 struct target_type *tt;
74
75 down_read(sem: &_lock);
76 list_for_each_entry(tt, &_targets, list)
77 iter_func(tt, param);
78 up_read(sem: &_lock);
79
80 return 0;
81}
82
83int dm_register_target(struct target_type *tt)
84{
85 int rv = 0;
86
87 down_write(sem: &_lock);
88 if (__find_target_type(name: tt->name)) {
89 DMERR("%s: '%s' target already registered",
90 __func__, tt->name);
91 rv = -EEXIST;
92 } else {
93 list_add(new: &tt->list, head: &_targets);
94 }
95 up_write(sem: &_lock);
96
97 return rv;
98}
99EXPORT_SYMBOL(dm_register_target);
100
101void dm_unregister_target(struct target_type *tt)
102{
103 down_write(sem: &_lock);
104 if (!__find_target_type(name: tt->name)) {
105 DMCRIT("Unregistering unrecognised target: %s", tt->name);
106 BUG();
107 }
108
109 list_del(entry: &tt->list);
110
111 up_write(sem: &_lock);
112}
113EXPORT_SYMBOL(dm_unregister_target);
114
115/*
116 * io-err: always fails an io, useful for bringing
117 * up LVs that have holes in them.
118 */
119struct io_err_c {
120 struct dm_dev *dev;
121 sector_t start;
122};
123
124static int io_err_get_args(struct dm_target *tt, unsigned int argc, char **args)
125{
126 unsigned long long start;
127 struct io_err_c *ioec;
128 char dummy;
129 int ret;
130
131 ioec = kmalloc(sizeof(*ioec), GFP_KERNEL);
132 if (!ioec) {
133 tt->error = "Cannot allocate io_err context";
134 return -ENOMEM;
135 }
136
137 ret = -EINVAL;
138 if (sscanf(args[1], "%llu%c", &start, &dummy) != 1 ||
139 start != (sector_t)start) {
140 tt->error = "Invalid device sector";
141 goto bad;
142 }
143 ioec->start = start;
144
145 ret = dm_get_device(ti: tt, path: args[0], mode: dm_table_get_mode(t: tt->table), result: &ioec->dev);
146 if (ret) {
147 tt->error = "Device lookup failed";
148 goto bad;
149 }
150
151 tt->private = ioec;
152
153 return 0;
154
155bad:
156 kfree(objp: ioec);
157
158 return ret;
159}
160
161static int io_err_ctr(struct dm_target *tt, unsigned int argc, char **args)
162{
163 /*
164 * If we have arguments, assume it is the path to the backing
165 * block device and its mapping start sector (same as dm-linear).
166 * In this case, get the device so that we can get its limits.
167 */
168 if (argc == 2) {
169 int ret = io_err_get_args(tt, argc, args);
170
171 if (ret)
172 return ret;
173 }
174
175 /*
176 * Return error for discards instead of -EOPNOTSUPP
177 */
178 tt->num_discard_bios = 1;
179 tt->discards_supported = true;
180
181 return 0;
182}
183
184static void io_err_dtr(struct dm_target *tt)
185{
186 struct io_err_c *ioec = tt->private;
187
188 if (ioec) {
189 dm_put_device(ti: tt, d: ioec->dev);
190 kfree(objp: ioec);
191 }
192}
193
194static int io_err_map(struct dm_target *tt, struct bio *bio)
195{
196 return DM_MAPIO_KILL;
197}
198
199static int io_err_clone_and_map_rq(struct dm_target *ti, struct request *rq,
200 union map_info *map_context,
201 struct request **clone)
202{
203 return DM_MAPIO_KILL;
204}
205
206static void io_err_release_clone_rq(struct request *clone,
207 union map_info *map_context)
208{
209}
210
211#ifdef CONFIG_BLK_DEV_ZONED
212static sector_t io_err_map_sector(struct dm_target *ti, sector_t bi_sector)
213{
214 struct io_err_c *ioec = ti->private;
215
216 return ioec->start + dm_target_offset(ti, bi_sector);
217}
218
219static int io_err_report_zones(struct dm_target *ti,
220 struct dm_report_zones_args *args, unsigned int nr_zones)
221{
222 struct io_err_c *ioec = ti->private;
223
224 /*
225 * This should never be called when we do not have a backing device
226 * as that mean the target is not a zoned one.
227 */
228 if (WARN_ON_ONCE(!ioec))
229 return -EIO;
230
231 return dm_report_zones(ioec->dev->bdev, ioec->start,
232 io_err_map_sector(ti, args->next_sector),
233 args, nr_zones);
234}
235#else
236#define io_err_report_zones NULL
237#endif
238
239static int io_err_iterate_devices(struct dm_target *ti,
240 iterate_devices_callout_fn fn, void *data)
241{
242 struct io_err_c *ioec = ti->private;
243
244 if (!ioec)
245 return 0;
246
247 return fn(ti, ioec->dev, ioec->start, ti->len, data);
248}
249
250static void io_err_io_hints(struct dm_target *ti, struct queue_limits *limits)
251{
252 limits->max_hw_discard_sectors = UINT_MAX;
253 limits->discard_granularity = 512;
254}
255
256static long io_err_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
257 long nr_pages, enum dax_access_mode mode, void **kaddr,
258 unsigned long *pfn)
259{
260 return -EIO;
261}
262
263static struct target_type error_target = {
264 .name = "error",
265 .version = {1, 7, 0},
266 .features = DM_TARGET_WILDCARD | DM_TARGET_ZONED_HM |
267 DM_TARGET_PASSES_INTEGRITY,
268 .ctr = io_err_ctr,
269 .dtr = io_err_dtr,
270 .map = io_err_map,
271 .clone_and_map_rq = io_err_clone_and_map_rq,
272 .release_clone_rq = io_err_release_clone_rq,
273 .iterate_devices = io_err_iterate_devices,
274 .io_hints = io_err_io_hints,
275 .direct_access = io_err_dax_direct_access,
276 .report_zones = io_err_report_zones,
277};
278
279int __init dm_target_init(void)
280{
281 return dm_register_target(&error_target);
282}
283
284void dm_target_exit(void)
285{
286 dm_unregister_target(&error_target);
287}
288