tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 *---------------------------------------------------------------*/
21struct transient_c {
22 sector_t next_free;
23};
24
25static void transient_dtr(struct dm_exception_store *store)
26{
27 kfree(store->context);
28}
29
30static 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
38static int transient_prepare_exception(struct dm_exception_store *store,
39 struct dm_snap_exception *e)
40{
41 struct transient_c *tc = store->context;
42 sector_t size = get_dev_size(store->cow->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
53static void transient_commit_exception(struct dm_exception_store *store,
54 struct dm_snap_exception *e,
55 void (*callback) (void *, int success),
56 void *callback_context)
57{
58 /* Just succeed */
59 callback(callback_context, 1);
60}
61
62static void transient_fraction_full(struct dm_exception_store *store,
63 sector_t *numerator, sector_t *denominator)
64{
65 *numerator = ((struct transient_c *) store->context)->next_free;
66 *denominator = get_dev_size(store->cow->bdev);
67}
68
69static int transient_ctr(struct dm_exception_store *store,
70 unsigned argc, char **argv)
71{
72 struct transient_c *tc;
73
74 tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL);
75 if (!tc)
76 return -ENOMEM;
77
78 tc->next_free = 0;
79 store->context = tc;
80
81 return 0;
82}
83
84static unsigned transient_status(struct dm_exception_store *store,
85 status_type_t status, char *result,
86 unsigned maxlen)
87{
88 unsigned sz = 0;
89
90 switch (status) {
91 case STATUSTYPE_INFO:
92 break;
93 case STATUSTYPE_TABLE:
94 DMEMIT(" %s N %llu", store->cow->name,
95 (unsigned long long)store->chunk_size);
96 }
97
98 return sz;
99}
100
101static struct dm_exception_store_type _transient_type = {
102 .name = "transient",
103 .module = THIS_MODULE,
104 .ctr = transient_ctr,
105 .dtr = transient_dtr,
106 .read_metadata = transient_read_metadata,
107 .prepare_exception = transient_prepare_exception,
108 .commit_exception = transient_commit_exception,
109 .fraction_full = transient_fraction_full,
110 .status = transient_status,
111};
112
113static struct dm_exception_store_type _transient_compat_type = {
114 .name = "N",
115 .module = THIS_MODULE,
116 .ctr = transient_ctr,
117 .dtr = transient_dtr,
118 .read_metadata = transient_read_metadata,
119 .prepare_exception = transient_prepare_exception,
120 .commit_exception = transient_commit_exception,
121 .fraction_full = transient_fraction_full,
122 .status = transient_status,
123};
124
125int dm_transient_snapshot_init(void)
126{
127 int r;
128
129 r = dm_exception_store_type_register(&_transient_type);
130 if (r) {
131 DMWARN("Unable to register transient exception store type");
132 return r;
133 }
134
135 r = dm_exception_store_type_register(&_transient_compat_type);
136 if (r) {
137 DMWARN("Unable to register old-style transient "
138 "exception store type");
139 dm_exception_store_type_unregister(&_transient_type);
140 return r;
141 }
142
143 return r;
144}
145
146void dm_transient_snapshot_exit(void)
147{
148 dm_exception_store_type_unregister(&_transient_type);
149 dm_exception_store_type_unregister(&_transient_compat_type);
150}