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
18 static LIST_HEAD(_targets);
19 static DECLARE_RWSEM(_lock);
20
__find_target_type(const char * name)21 static 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
get_target_type(const char * name)32 static struct target_type *get_target_type(const char *name)
33 {
34 struct target_type *tt;
35
36 down_read(&_lock);
37
38 tt = __find_target_type(name);
39 if (tt && !try_module_get(tt->module))
40 tt = NULL;
41
42 up_read(&_lock);
43 return tt;
44 }
45
load_module(const char * name)46 static void load_module(const char *name)
47 {
48 request_module("dm-%s", name);
49 }
50
dm_get_target_type(const char * name)51 struct 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
dm_put_target_type(struct target_type * tt)63 void dm_put_target_type(struct target_type *tt)
64 {
65 down_read(&_lock);
66 module_put(tt->module);
67 up_read(&_lock);
68 }
69
dm_target_iterate(void (* iter_func)(struct target_type * tt,void * param),void * param)70 int 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(&_lock);
76 list_for_each_entry(tt, &_targets, list)
77 iter_func(tt, param);
78 up_read(&_lock);
79
80 return 0;
81 }
82
dm_register_target(struct target_type * tt)83 int dm_register_target(struct target_type *tt)
84 {
85 int rv = 0;
86
87 down_write(&_lock);
88 if (__find_target_type(tt->name)) {
89 DMERR("%s: '%s' target already registered",
90 __func__, tt->name);
91 rv = -EEXIST;
92 } else {
93 list_add(&tt->list, &_targets);
94 }
95 up_write(&_lock);
96
97 return rv;
98 }
99 EXPORT_SYMBOL(dm_register_target);
100
dm_unregister_target(struct target_type * tt)101 void dm_unregister_target(struct target_type *tt)
102 {
103 down_write(&_lock);
104 if (!__find_target_type(tt->name)) {
105 DMCRIT("Unregistering unrecognised target: %s", tt->name);
106 BUG();
107 }
108
109 list_del(&tt->list);
110
111 up_write(&_lock);
112 }
113 EXPORT_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 */
119 struct io_err_c {
120 struct dm_dev *dev;
121 sector_t start;
122 };
123
io_err_get_args(struct dm_target * tt,unsigned int argc,char ** args)124 static 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(tt, args[0], dm_table_get_mode(tt->table), &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
155 bad:
156 kfree(ioec);
157
158 return ret;
159 }
160
io_err_ctr(struct dm_target * tt,unsigned int argc,char ** args)161 static 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
io_err_dtr(struct dm_target * tt)184 static 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(tt, ioec->dev);
190 kfree(ioec);
191 }
192 }
193
io_err_map(struct dm_target * tt,struct bio * bio)194 static int io_err_map(struct dm_target *tt, struct bio *bio)
195 {
196 return DM_MAPIO_KILL;
197 }
198
io_err_clone_and_map_rq(struct dm_target * ti,struct request * rq,union map_info * map_context,struct request ** clone)199 static 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
io_err_release_clone_rq(struct request * clone,union map_info * map_context)206 static void io_err_release_clone_rq(struct request *clone,
207 union map_info *map_context)
208 {
209 }
210
211 #ifdef CONFIG_BLK_DEV_ZONED
io_err_map_sector(struct dm_target * ti,sector_t bi_sector)212 static 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
io_err_report_zones(struct dm_target * ti,struct dm_report_zones_args * args,unsigned int nr_zones)219 static 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
io_err_iterate_devices(struct dm_target * ti,iterate_devices_callout_fn fn,void * data)239 static 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
io_err_io_hints(struct dm_target * ti,struct queue_limits * limits)250 static 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
io_err_dax_direct_access(struct dm_target * ti,pgoff_t pgoff,long nr_pages,enum dax_access_mode mode,void ** kaddr,pfn_t * pfn)256 static 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 pfn_t *pfn)
259 {
260 return -EIO;
261 }
262
263 static struct target_type error_target = {
264 .name = "error",
265 .version = {1, 7, 0},
266 .features = DM_TARGET_WILDCARD | DM_TARGET_ZONED_HM,
267 .ctr = io_err_ctr,
268 .dtr = io_err_dtr,
269 .map = io_err_map,
270 .clone_and_map_rq = io_err_clone_and_map_rq,
271 .release_clone_rq = io_err_release_clone_rq,
272 .iterate_devices = io_err_iterate_devices,
273 .io_hints = io_err_io_hints,
274 .direct_access = io_err_dax_direct_access,
275 .report_zones = io_err_report_zones,
276 };
277
dm_target_init(void)278 int __init dm_target_init(void)
279 {
280 return dm_register_target(&error_target);
281 }
282
dm_target_exit(void)283 void dm_target_exit(void)
284 {
285 dm_unregister_target(&error_target);
286 }
287