Merge branches 'fixes', 'cleanups' and 'boards'
[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 #include "dm-snap.h"
10
11 #include <linux/mm.h>
12 #include <linux/pagemap.h>
13 #include <linux/vmalloc.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  *---------------------------------------------------------------*/
22 struct transient_c {
23         sector_t next_free;
24 };
25
26 static void transient_destroy(struct dm_exception_store *store)
27 {
28         kfree(store->context);
29 }
30
31 static 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
39 static int transient_prepare_exception(struct dm_exception_store *store,
40                                        struct dm_snap_exception *e)
41 {
42         struct transient_c *tc = (struct transient_c *) store->context;
43         sector_t size = get_dev_size(store->snap->cow->bdev);
44
45         if (size < (tc->next_free + store->snap->chunk_size))
46                 return -1;
47
48         e->new_chunk = sector_to_chunk(store->snap, tc->next_free);
49         tc->next_free += store->snap->chunk_size;
50
51         return 0;
52 }
53
54 static void transient_commit_exception(struct dm_exception_store *store,
55                                        struct dm_snap_exception *e,
56                                        void (*callback) (void *, int success),
57                                        void *callback_context)
58 {
59         /* Just succeed */
60         callback(callback_context, 1);
61 }
62
63 static void transient_fraction_full(struct dm_exception_store *store,
64                                     sector_t *numerator, sector_t *denominator)
65 {
66         *numerator = ((struct transient_c *) store->context)->next_free;
67         *denominator = get_dev_size(store->snap->cow->bdev);
68 }
69
70 int dm_create_transient(struct dm_exception_store *store)
71 {
72         struct transient_c *tc;
73
74         store->destroy = transient_destroy;
75         store->read_metadata = transient_read_metadata;
76         store->prepare_exception = transient_prepare_exception;
77         store->commit_exception = transient_commit_exception;
78         store->drop_snapshot = NULL;
79         store->fraction_full = transient_fraction_full;
80
81         tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL);
82         if (!tc)
83                 return -ENOMEM;
84
85         tc->next_free = 0;
86         store->context = tc;
87
88         return 0;
89 }
90
91 int dm_transient_snapshot_init(void)
92 {
93         return 0;
94 }
95
96 void dm_transient_snapshot_exit(void)
97 {
98 }