Merge branch 'for-2.6.30' of git://linux-nfs.org/~bfields/linux
[linux-2.6] / drivers / md / dm-snap-transient.c
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_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
53 static 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
62 static 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
69 static 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
84 static 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
101 static 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
113 static 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
125 int 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
146 void dm_transient_snapshot_exit(void)
147 {
148         dm_exception_store_type_unregister(&_transient_type);
149         dm_exception_store_type_unregister(&_transient_compat_type);
150 }