1 /*
2 * Copyright (C) 2001-2002 Sistina Software (UK) Limited.
3 * Copyright (C) 2006-2008 Red Hat GmbH
4 *
5 * This file is released under the GPL.
6 */
7
8 #include "dm-exception-store.h"
9
10 #include <linux/mm.h>
11 #include <linux/pagemap.h>
12 #include <linux/vmalloc.h>
13 #include <linux/slab.h>
14 #include <linux/dm-io.h>
15
16 #define DM_MSG_PREFIX "transient snapshot"
17
18 /*-----------------------------------------------------------------
19 * Implementation of the store for non-persistent snapshots.
20 *---------------------------------------------------------------*/
21 struct transient_c {
22 sector_t next_free;
23 };
24
transient_dtr(struct dm_exception_store * store)25 static void transient_dtr(struct dm_exception_store *store)
26 {
27 kfree(store->context);
28 }
29
transient_read_metadata(struct dm_exception_store * store,int (* callback)(void * callback_context,chunk_t old,chunk_t new),void * callback_context)30 static int transient_read_metadata(struct dm_exception_store *store,
31 int (*callback)(void *callback_context,
32 chunk_t old, chunk_t new),
33 void *callback_context)
34 {
35 return 0;
36 }
37
transient_prepare_exception(struct dm_exception_store * store,struct dm_exception * e)38 static int transient_prepare_exception(struct dm_exception_store *store,
39 struct dm_exception *e)
40 {
41 struct transient_c *tc = store->context;
42 sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev);
43
44 if (size < (tc->next_free + store->chunk_size))
45 return -1;
46
47 e->new_chunk = sector_to_chunk(store, tc->next_free);
48 tc->next_free += store->chunk_size;
49
50 return 0;
51 }
52
transient_commit_exception(struct dm_exception_store * store,struct dm_exception * e,void (* callback)(void *,int success),void * callback_context)53 static void transient_commit_exception(struct dm_exception_store *store,
54 struct dm_exception *e,
55 void (*callback) (void *, int success),
56 void *callback_context)
57 {
58 /* Just succeed */
59 callback(callback_context, 1);
60 }
61
transient_usage(struct dm_exception_store * store,sector_t * total_sectors,sector_t * sectors_allocated,sector_t * metadata_sectors)62 static void transient_usage(struct dm_exception_store *store,
63 sector_t *total_sectors,
64 sector_t *sectors_allocated,
65 sector_t *metadata_sectors)
66 {
67 *sectors_allocated = ((struct transient_c *) store->context)->next_free;
68 *total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev);
69 *metadata_sectors = 0;
70 }
71
transient_ctr(struct dm_exception_store * store,unsigned argc,char ** argv)72 static int transient_ctr(struct dm_exception_store *store,
73 unsigned argc, char **argv)
74 {
75 struct transient_c *tc;
76
77 tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL);
78 if (!tc)
79 return -ENOMEM;
80
81 tc->next_free = 0;
82 store->context = tc;
83
84 return 0;
85 }
86
transient_status(struct dm_exception_store * store,status_type_t status,char * result,unsigned maxlen)87 static unsigned transient_status(struct dm_exception_store *store,
88 status_type_t status, char *result,
89 unsigned maxlen)
90 {
91 unsigned sz = 0;
92
93 switch (status) {
94 case STATUSTYPE_INFO:
95 break;
96 case STATUSTYPE_TABLE:
97 DMEMIT(" N %llu", (unsigned long long)store->chunk_size);
98 }
99
100 return sz;
101 }
102
103 static struct dm_exception_store_type _transient_type = {
104 .name = "transient",
105 .module = THIS_MODULE,
106 .ctr = transient_ctr,
107 .dtr = transient_dtr,
108 .read_metadata = transient_read_metadata,
109 .prepare_exception = transient_prepare_exception,
110 .commit_exception = transient_commit_exception,
111 .usage = transient_usage,
112 .status = transient_status,
113 };
114
115 static struct dm_exception_store_type _transient_compat_type = {
116 .name = "N",
117 .module = THIS_MODULE,
118 .ctr = transient_ctr,
119 .dtr = transient_dtr,
120 .read_metadata = transient_read_metadata,
121 .prepare_exception = transient_prepare_exception,
122 .commit_exception = transient_commit_exception,
123 .usage = transient_usage,
124 .status = transient_status,
125 };
126
dm_transient_snapshot_init(void)127 int dm_transient_snapshot_init(void)
128 {
129 int r;
130
131 r = dm_exception_store_type_register(&_transient_type);
132 if (r) {
133 DMWARN("Unable to register transient exception store type");
134 return r;
135 }
136
137 r = dm_exception_store_type_register(&_transient_compat_type);
138 if (r) {
139 DMWARN("Unable to register old-style transient "
140 "exception store type");
141 dm_exception_store_type_unregister(&_transient_type);
142 return r;
143 }
144
145 return r;
146 }
147
dm_transient_snapshot_exit(void)148 void dm_transient_snapshot_exit(void)
149 {
150 dm_exception_store_type_unregister(&_transient_type);
151 dm_exception_store_type_unregister(&_transient_compat_type);
152 }
153