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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * Copyright (C) 2001-2002 Sistina Software (UK) Limited.
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +00003 * Copyright (C) 2006-2008 Red Hat GmbH
Linus Torvalds1da177e2005-04-16 15:20:36 -07004 *
5 * This file is released under the GPL.
6 */
7
Jonathan Brassowaea53d92009-01-06 03:05:15 +00008#include "dm-exception-store.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -07009
Jonathan Brassowfee19982009-04-02 19:55:34 +010010#include <linux/ctype.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#include <linux/mm.h>
12#include <linux/pagemap.h>
13#include <linux/vmalloc.h>
14#include <linux/slab.h>
15
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +000016#define DM_MSG_PREFIX "snapshot exception stores"
Alasdair G Kergon72d94862006-06-26 00:27:35 -070017
Jonathan Brassow493df712009-04-02 19:55:31 +010018static LIST_HEAD(_exception_store_types);
19static DEFINE_SPINLOCK(_lock);
20
21static struct dm_exception_store_type *__find_exception_store_type(const char *name)
22{
23 struct dm_exception_store_type *type;
24
25 list_for_each_entry(type, &_exception_store_types, list)
26 if (!strcmp(name, type->name))
27 return type;
28
29 return NULL;
30}
31
32static struct dm_exception_store_type *_get_exception_store_type(const char *name)
33{
34 struct dm_exception_store_type *type;
35
36 spin_lock(&_lock);
37
38 type = __find_exception_store_type(name);
39
40 if (type && !try_module_get(type->module))
41 type = NULL;
42
43 spin_unlock(&_lock);
44
45 return type;
46}
47
48/*
49 * get_type
50 * @type_name
51 *
52 * Attempt to retrieve the dm_exception_store_type by name. If not already
53 * available, attempt to load the appropriate module.
54 *
55 * Exstore modules are named "dm-exstore-" followed by the 'type_name'.
56 * Modules may contain multiple types.
57 * This function will first try the module "dm-exstore-<type_name>",
58 * then truncate 'type_name' on the last '-' and try again.
59 *
60 * For example, if type_name was "clustered-shared", it would search
61 * 'dm-exstore-clustered-shared' then 'dm-exstore-clustered'.
62 *
63 * 'dm-exception-store-<type_name>' is too long of a name in my
64 * opinion, which is why I've chosen to have the files
65 * containing exception store implementations be 'dm-exstore-<type_name>'.
66 * If you want your module to be autoloaded, you will follow this
67 * naming convention.
68 *
69 * Returns: dm_exception_store_type* on success, NULL on failure
70 */
71static struct dm_exception_store_type *get_type(const char *type_name)
72{
73 char *p, *type_name_dup;
74 struct dm_exception_store_type *type;
75
76 type = _get_exception_store_type(type_name);
77 if (type)
78 return type;
79
80 type_name_dup = kstrdup(type_name, GFP_KERNEL);
81 if (!type_name_dup) {
82 DMERR("No memory left to attempt load for \"%s\"", type_name);
83 return NULL;
84 }
85
86 while (request_module("dm-exstore-%s", type_name_dup) ||
87 !(type = _get_exception_store_type(type_name))) {
88 p = strrchr(type_name_dup, '-');
89 if (!p)
90 break;
91 p[0] = '\0';
92 }
93
94 if (!type)
95 DMWARN("Module for exstore type \"%s\" not found.", type_name);
96
97 kfree(type_name_dup);
98
99 return type;
100}
101
102static void put_type(struct dm_exception_store_type *type)
103{
104 spin_lock(&_lock);
105 module_put(type->module);
106 spin_unlock(&_lock);
107}
108
109int dm_exception_store_type_register(struct dm_exception_store_type *type)
110{
111 int r = 0;
112
113 spin_lock(&_lock);
114 if (!__find_exception_store_type(type->name))
115 list_add(&type->list, &_exception_store_types);
116 else
117 r = -EEXIST;
118 spin_unlock(&_lock);
119
120 return r;
121}
122EXPORT_SYMBOL(dm_exception_store_type_register);
123
124int dm_exception_store_type_unregister(struct dm_exception_store_type *type)
125{
126 spin_lock(&_lock);
127
128 if (!__find_exception_store_type(type->name)) {
129 spin_unlock(&_lock);
130 return -EINVAL;
131 }
132
133 list_del(&type->list);
134
135 spin_unlock(&_lock);
136
137 return 0;
138}
139EXPORT_SYMBOL(dm_exception_store_type_unregister);
140
Jonathan Brassowfee19982009-04-02 19:55:34 +0100141static int set_chunk_size(struct dm_exception_store *store,
142 const char *chunk_size_arg, char **error)
143{
144 unsigned long chunk_size_ulong;
145 char *value;
146
147 chunk_size_ulong = simple_strtoul(chunk_size_arg, &value, 10);
Mikulas Patockadf96eee2009-10-16 23:18:17 +0100148 if (*chunk_size_arg == '\0' || *value != '\0' ||
149 chunk_size_ulong > UINT_MAX) {
Jonathan Brassowfee19982009-04-02 19:55:34 +0100150 *error = "Invalid chunk size";
151 return -EINVAL;
152 }
153
154 if (!chunk_size_ulong) {
155 store->chunk_size = store->chunk_mask = store->chunk_shift = 0;
156 return 0;
157 }
158
Mikulas Patockadf96eee2009-10-16 23:18:17 +0100159 return dm_exception_store_set_chunk_size(store,
160 (unsigned) chunk_size_ulong,
Mikulas Patocka2defcc32009-09-04 20:40:41 +0100161 error);
162}
163
164int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
Mikulas Patockadf96eee2009-10-16 23:18:17 +0100165 unsigned chunk_size,
Mikulas Patocka2defcc32009-09-04 20:40:41 +0100166 char **error)
167{
Jonathan Brassowfee19982009-04-02 19:55:34 +0100168 /* Check chunk_size is a power of 2 */
Mikulas Patockadf96eee2009-10-16 23:18:17 +0100169 if (!is_power_of_2(chunk_size)) {
Jonathan Brassowfee19982009-04-02 19:55:34 +0100170 *error = "Chunk size is not a power of 2";
171 return -EINVAL;
172 }
173
174 /* Validate the chunk size against the device block size */
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000175 if (chunk_size %
Mikulas Patockac2411042010-08-12 04:13:51 +0100176 (bdev_logical_block_size(dm_snap_cow(store->snap)->bdev) >> 9) ||
177 chunk_size %
178 (bdev_logical_block_size(dm_snap_origin(store->snap)->bdev) >> 9)) {
Jonathan Brassowfee19982009-04-02 19:55:34 +0100179 *error = "Chunk size is not a multiple of device blocksize";
180 return -EINVAL;
181 }
182
Mikulas Patockadf96eee2009-10-16 23:18:17 +0100183 if (chunk_size > INT_MAX >> SECTOR_SHIFT) {
Mikulas Patockaae0b7442009-09-04 20:40:43 +0100184 *error = "Chunk size is too high";
185 return -EINVAL;
186 }
187
Mikulas Patockadf96eee2009-10-16 23:18:17 +0100188 store->chunk_size = chunk_size;
189 store->chunk_mask = chunk_size - 1;
190 store->chunk_shift = ffs(chunk_size) - 1;
Jonathan Brassowfee19982009-04-02 19:55:34 +0100191
192 return 0;
193}
194
195int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000196 struct dm_snapshot *snap,
Jonathan Brassowfee19982009-04-02 19:55:34 +0100197 unsigned *args_used,
Jonathan Brassow493df712009-04-02 19:55:31 +0100198 struct dm_exception_store **store)
199{
200 int r = 0;
Milan Broz874d2f62009-06-30 15:18:14 +0100201 struct dm_exception_store_type *type = NULL;
Jonathan Brassow493df712009-04-02 19:55:31 +0100202 struct dm_exception_store *tmp_store;
Jonathan Brassowfee19982009-04-02 19:55:34 +0100203 char persistent;
204
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000205 if (argc < 2) {
Jonathan Brassowfee19982009-04-02 19:55:34 +0100206 ti->error = "Insufficient exception store arguments";
207 return -EINVAL;
208 }
Jonathan Brassow493df712009-04-02 19:55:31 +0100209
210 tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL);
Jonathan Brassowfee19982009-04-02 19:55:34 +0100211 if (!tmp_store) {
212 ti->error = "Exception store allocation failed";
Jonathan Brassow493df712009-04-02 19:55:31 +0100213 return -ENOMEM;
Jonathan Brassowfee19982009-04-02 19:55:34 +0100214 }
Jonathan Brassow493df712009-04-02 19:55:31 +0100215
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000216 persistent = toupper(*argv[0]);
Milan Broz874d2f62009-06-30 15:18:14 +0100217 if (persistent == 'P')
218 type = get_type("P");
219 else if (persistent == 'N')
220 type = get_type("N");
221 else {
Jonathan Brassowfee19982009-04-02 19:55:34 +0100222 ti->error = "Persistent flag is not P or N";
Julia Lawall613978f2009-12-10 23:51:52 +0000223 r = -EINVAL;
224 goto bad_type;
Jonathan Brassow493df712009-04-02 19:55:31 +0100225 }
226
Jonathan Brassowfee19982009-04-02 19:55:34 +0100227 if (!type) {
228 ti->error = "Exception store type not recognised";
229 r = -EINVAL;
230 goto bad_type;
231 }
232
Jonathan Brassow493df712009-04-02 19:55:31 +0100233 tmp_store->type = type;
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000234 tmp_store->snap = snap;
Jonathan Brassow493df712009-04-02 19:55:31 +0100235
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000236 r = set_chunk_size(tmp_store, argv[1], &ti->error);
Jonathan Brassowfee19982009-04-02 19:55:34 +0100237 if (r)
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000238 goto bad;
Jonathan Brassow49beb2b2009-04-02 19:55:33 +0100239
Jonathan Brassow493df712009-04-02 19:55:31 +0100240 r = type->ctr(tmp_store, 0, NULL);
241 if (r) {
Jonathan Brassowfee19982009-04-02 19:55:34 +0100242 ti->error = "Exception store type constructor failed";
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000243 goto bad;
Jonathan Brassow493df712009-04-02 19:55:31 +0100244 }
245
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000246 *args_used = 2;
Jonathan Brassow493df712009-04-02 19:55:31 +0100247 *store = tmp_store;
248 return 0;
Jonathan Brassowfee19982009-04-02 19:55:34 +0100249
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000250bad:
Jonathan Brassowfee19982009-04-02 19:55:34 +0100251 put_type(type);
252bad_type:
253 kfree(tmp_store);
254 return r;
Jonathan Brassow493df712009-04-02 19:55:31 +0100255}
256EXPORT_SYMBOL(dm_exception_store_create);
257
258void dm_exception_store_destroy(struct dm_exception_store *store)
259{
260 store->type->dtr(store);
261 put_type(store->type);
262 kfree(store);
263}
264EXPORT_SYMBOL(dm_exception_store_destroy);
265
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000266int dm_exception_store_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267{
268 int r;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000270 r = dm_transient_snapshot_init();
271 if (r) {
272 DMERR("Unable to register transient exception store type.");
273 goto transient_fail;
274 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000276 r = dm_persistent_snapshot_init();
277 if (r) {
278 DMERR("Unable to register persistent exception store type");
279 goto persistent_fail;
280 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000284persistent_fail:
285 dm_persistent_snapshot_exit();
286transient_fail:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 return r;
288}
289
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000290void dm_exception_store_exit(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291{
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000292 dm_persistent_snapshot_exit();
293 dm_transient_snapshot_exit();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294}