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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 | |
25 | static void transient_dtr(struct dm_exception_store *store) |
26 | { |
27 | kfree(store->context); |
28 | } |
29 | |
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 | |
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 | |
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 | |
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 | |
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 | |
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 | |
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 | |
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 |
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