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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>
Paul Gortmaker056075c2011-07-03 13:58:33 -040014#include <linux/module.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include <linux/slab.h>
16
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +000017#define DM_MSG_PREFIX "snapshot exception stores"
Alasdair G Kergon72d94862006-06-26 00:27:35 -070018
Jonathan Brassow493df712009-04-02 19:55:31 +010019static LIST_HEAD(_exception_store_types);
20static DEFINE_SPINLOCK(_lock);
21
22static struct dm_exception_store_type *__find_exception_store_type(const char *name)
23{
24 struct dm_exception_store_type *type;
25
26 list_for_each_entry(type, &_exception_store_types, list)
27 if (!strcmp(name, type->name))
28 return type;
29
30 return NULL;
31}
32
33static struct dm_exception_store_type *_get_exception_store_type(const char *name)
34{
35 struct dm_exception_store_type *type;
36
37 spin_lock(&_lock);
38
39 type = __find_exception_store_type(name);
40
41 if (type && !try_module_get(type->module))
42 type = NULL;
43
44 spin_unlock(&_lock);
45
46 return type;
47}
48
49/*
50 * get_type
51 * @type_name
52 *
53 * Attempt to retrieve the dm_exception_store_type by name. If not already
54 * available, attempt to load the appropriate module.
55 *
56 * Exstore modules are named "dm-exstore-" followed by the 'type_name'.
57 * Modules may contain multiple types.
58 * This function will first try the module "dm-exstore-<type_name>",
59 * then truncate 'type_name' on the last '-' and try again.
60 *
61 * For example, if type_name was "clustered-shared", it would search
62 * 'dm-exstore-clustered-shared' then 'dm-exstore-clustered'.
63 *
64 * 'dm-exception-store-<type_name>' is too long of a name in my
65 * opinion, which is why I've chosen to have the files
66 * containing exception store implementations be 'dm-exstore-<type_name>'.
67 * If you want your module to be autoloaded, you will follow this
68 * naming convention.
69 *
70 * Returns: dm_exception_store_type* on success, NULL on failure
71 */
72static struct dm_exception_store_type *get_type(const char *type_name)
73{
74 char *p, *type_name_dup;
75 struct dm_exception_store_type *type;
76
77 type = _get_exception_store_type(type_name);
78 if (type)
79 return type;
80
81 type_name_dup = kstrdup(type_name, GFP_KERNEL);
82 if (!type_name_dup) {
83 DMERR("No memory left to attempt load for \"%s\"", type_name);
84 return NULL;
85 }
86
87 while (request_module("dm-exstore-%s", type_name_dup) ||
88 !(type = _get_exception_store_type(type_name))) {
89 p = strrchr(type_name_dup, '-');
90 if (!p)
91 break;
92 p[0] = '\0';
93 }
94
95 if (!type)
96 DMWARN("Module for exstore type \"%s\" not found.", type_name);
97
98 kfree(type_name_dup);
99
100 return type;
101}
102
103static void put_type(struct dm_exception_store_type *type)
104{
105 spin_lock(&_lock);
106 module_put(type->module);
107 spin_unlock(&_lock);
108}
109
110int dm_exception_store_type_register(struct dm_exception_store_type *type)
111{
112 int r = 0;
113
114 spin_lock(&_lock);
115 if (!__find_exception_store_type(type->name))
116 list_add(&type->list, &_exception_store_types);
117 else
118 r = -EEXIST;
119 spin_unlock(&_lock);
120
121 return r;
122}
123EXPORT_SYMBOL(dm_exception_store_type_register);
124
125int dm_exception_store_type_unregister(struct dm_exception_store_type *type)
126{
127 spin_lock(&_lock);
128
129 if (!__find_exception_store_type(type->name)) {
130 spin_unlock(&_lock);
131 return -EINVAL;
132 }
133
134 list_del(&type->list);
135
136 spin_unlock(&_lock);
137
138 return 0;
139}
140EXPORT_SYMBOL(dm_exception_store_type_unregister);
141
Jonathan Brassowfee19982009-04-02 19:55:34 +0100142static int set_chunk_size(struct dm_exception_store *store,
143 const char *chunk_size_arg, char **error)
144{
145 unsigned long chunk_size_ulong;
146 char *value;
147
148 chunk_size_ulong = simple_strtoul(chunk_size_arg, &value, 10);
Mikulas Patockadf96eee2009-10-16 23:18:17 +0100149 if (*chunk_size_arg == '\0' || *value != '\0' ||
150 chunk_size_ulong > UINT_MAX) {
Jonathan Brassowfee19982009-04-02 19:55:34 +0100151 *error = "Invalid chunk size";
152 return -EINVAL;
153 }
154
155 if (!chunk_size_ulong) {
156 store->chunk_size = store->chunk_mask = store->chunk_shift = 0;
157 return 0;
158 }
159
Mikulas Patockadf96eee2009-10-16 23:18:17 +0100160 return dm_exception_store_set_chunk_size(store,
161 (unsigned) chunk_size_ulong,
Mikulas Patocka2defcc32009-09-04 20:40:41 +0100162 error);
163}
164
165int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
Mikulas Patockadf96eee2009-10-16 23:18:17 +0100166 unsigned chunk_size,
Mikulas Patocka2defcc32009-09-04 20:40:41 +0100167 char **error)
168{
Jonathan Brassowfee19982009-04-02 19:55:34 +0100169 /* Check chunk_size is a power of 2 */
Mikulas Patockadf96eee2009-10-16 23:18:17 +0100170 if (!is_power_of_2(chunk_size)) {
Jonathan Brassowfee19982009-04-02 19:55:34 +0100171 *error = "Chunk size is not a power of 2";
172 return -EINVAL;
173 }
174
175 /* Validate the chunk size against the device block size */
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000176 if (chunk_size %
Mikulas Patockac2411042010-08-12 04:13:51 +0100177 (bdev_logical_block_size(dm_snap_cow(store->snap)->bdev) >> 9) ||
178 chunk_size %
179 (bdev_logical_block_size(dm_snap_origin(store->snap)->bdev) >> 9)) {
Jonathan Brassowfee19982009-04-02 19:55:34 +0100180 *error = "Chunk size is not a multiple of device blocksize";
181 return -EINVAL;
182 }
183
Mikulas Patockadf96eee2009-10-16 23:18:17 +0100184 if (chunk_size > INT_MAX >> SECTOR_SHIFT) {
Mikulas Patockaae0b7442009-09-04 20:40:43 +0100185 *error = "Chunk size is too high";
186 return -EINVAL;
187 }
188
Mikulas Patockadf96eee2009-10-16 23:18:17 +0100189 store->chunk_size = chunk_size;
190 store->chunk_mask = chunk_size - 1;
191 store->chunk_shift = ffs(chunk_size) - 1;
Jonathan Brassowfee19982009-04-02 19:55:34 +0100192
193 return 0;
194}
195
196int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000197 struct dm_snapshot *snap,
Jonathan Brassowfee19982009-04-02 19:55:34 +0100198 unsigned *args_used,
Jonathan Brassow493df712009-04-02 19:55:31 +0100199 struct dm_exception_store **store)
200{
201 int r = 0;
Milan Broz874d2f62009-06-30 15:18:14 +0100202 struct dm_exception_store_type *type = NULL;
Jonathan Brassow493df712009-04-02 19:55:31 +0100203 struct dm_exception_store *tmp_store;
Jonathan Brassowfee19982009-04-02 19:55:34 +0100204 char persistent;
205
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000206 if (argc < 2) {
Jonathan Brassowfee19982009-04-02 19:55:34 +0100207 ti->error = "Insufficient exception store arguments";
208 return -EINVAL;
209 }
Jonathan Brassow493df712009-04-02 19:55:31 +0100210
211 tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL);
Jonathan Brassowfee19982009-04-02 19:55:34 +0100212 if (!tmp_store) {
213 ti->error = "Exception store allocation failed";
Jonathan Brassow493df712009-04-02 19:55:31 +0100214 return -ENOMEM;
Jonathan Brassowfee19982009-04-02 19:55:34 +0100215 }
Jonathan Brassow493df712009-04-02 19:55:31 +0100216
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000217 persistent = toupper(*argv[0]);
Milan Broz874d2f62009-06-30 15:18:14 +0100218 if (persistent == 'P')
219 type = get_type("P");
220 else if (persistent == 'N')
221 type = get_type("N");
222 else {
Jonathan Brassowfee19982009-04-02 19:55:34 +0100223 ti->error = "Persistent flag is not P or N";
Julia Lawall613978f2009-12-10 23:51:52 +0000224 r = -EINVAL;
225 goto bad_type;
Jonathan Brassow493df712009-04-02 19:55:31 +0100226 }
227
Jonathan Brassowfee19982009-04-02 19:55:34 +0100228 if (!type) {
229 ti->error = "Exception store type not recognised";
230 r = -EINVAL;
231 goto bad_type;
232 }
233
Jonathan Brassow493df712009-04-02 19:55:31 +0100234 tmp_store->type = type;
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000235 tmp_store->snap = snap;
Jonathan Brassow493df712009-04-02 19:55:31 +0100236
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000237 r = set_chunk_size(tmp_store, argv[1], &ti->error);
Jonathan Brassowfee19982009-04-02 19:55:34 +0100238 if (r)
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000239 goto bad;
Jonathan Brassow49beb2b2009-04-02 19:55:33 +0100240
Jonathan Brassow493df712009-04-02 19:55:31 +0100241 r = type->ctr(tmp_store, 0, NULL);
242 if (r) {
Jonathan Brassowfee19982009-04-02 19:55:34 +0100243 ti->error = "Exception store type constructor failed";
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000244 goto bad;
Jonathan Brassow493df712009-04-02 19:55:31 +0100245 }
246
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000247 *args_used = 2;
Jonathan Brassow493df712009-04-02 19:55:31 +0100248 *store = tmp_store;
249 return 0;
Jonathan Brassowfee19982009-04-02 19:55:34 +0100250
Mike Snitzerfc56f6f2009-12-10 23:52:12 +0000251bad:
Jonathan Brassowfee19982009-04-02 19:55:34 +0100252 put_type(type);
253bad_type:
254 kfree(tmp_store);
255 return r;
Jonathan Brassow493df712009-04-02 19:55:31 +0100256}
257EXPORT_SYMBOL(dm_exception_store_create);
258
259void dm_exception_store_destroy(struct dm_exception_store *store)
260{
261 store->type->dtr(store);
262 put_type(store->type);
263 kfree(store);
264}
265EXPORT_SYMBOL(dm_exception_store_destroy);
266
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000267int dm_exception_store_init(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268{
269 int r;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000271 r = dm_transient_snapshot_init();
272 if (r) {
273 DMERR("Unable to register transient exception store type.");
274 goto transient_fail;
275 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000277 r = dm_persistent_snapshot_init();
278 if (r) {
279 DMERR("Unable to register persistent exception store type");
280 goto persistent_fail;
281 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000285persistent_fail:
Andrei Warkentinaadbe262012-03-28 18:41:22 +0100286 dm_transient_snapshot_exit();
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000287transient_fail:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 return r;
289}
290
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000291void dm_exception_store_exit(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292{
Alasdair G Kergon4db6bfe2009-01-06 03:05:17 +0000293 dm_persistent_snapshot_exit();
294 dm_transient_snapshot_exit();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295}