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/export.h>
14#include <linux/slab.h>
15#include <linux/dm-io.h>
16
17#define DM_MSG_PREFIX "transient snapshot"
18
19/*-----------------------------------------------------------------
20 * Implementation of the store for non-persistent snapshots.
21 *---------------------------------------------------------------*/
22struct transient_c {
23 sector_t next_free;
24};
25
26static void transient_dtr(struct dm_exception_store *store)
27{
28 kfree(store->context);
29}
30
31static int transient_read_metadata(struct dm_exception_store *store,
32 int (*callback)(void *callback_context,
33 chunk_t old, chunk_t new),
34 void *callback_context)
35{
36 return 0;
37}
38
39static int transient_prepare_exception(struct dm_exception_store *store,
40 struct dm_exception *e)
41{
42 struct transient_c *tc = store->context;
43 sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev);
44
45 if (size < (tc->next_free + store->chunk_size))
46 return -1;
47
48 e->new_chunk = sector_to_chunk(store, tc->next_free);
49 tc->next_free += store->chunk_size;
50
51 return 0;
52}
53
54static void transient_commit_exception(struct dm_exception_store *store,
55 struct dm_exception *e, int valid,
56 void (*callback) (void *, int success),
57 void *callback_context)
58{
59 /* Just succeed */
60 callback(callback_context, valid);
61}
62
63static void transient_usage(struct dm_exception_store *store,
64 sector_t *total_sectors,
65 sector_t *sectors_allocated,
66 sector_t *metadata_sectors)
67{
68 *sectors_allocated = ((struct transient_c *) store->context)->next_free;
69 *total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev);
70 *metadata_sectors = 0;
71}
72
73static int transient_ctr(struct dm_exception_store *store, char *options)
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
87static 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
103static 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
115static 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
127int 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
148void 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