summaryrefslogtreecommitdiff
path: root/drivers/md/dm-snap-transient.c
blob: cde5aa558e6d77b7d1130777762f8aec84c86ab1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
/*
 * Copyright (C) 2001-2002 Sistina Software (UK) Limited.
 * Copyright (C) 2006-2008 Red Hat GmbH
 *
 * This file is released under the GPL.
 */

#include "dm-exception-store.h"

#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/dm-io.h>

#define DM_MSG_PREFIX "transient snapshot"

/*-----------------------------------------------------------------
 * Implementation of the store for non-persistent snapshots.
 *---------------------------------------------------------------*/
struct transient_c {
	sector_t next_free;
};

static void transient_dtr(struct dm_exception_store *store)
{
	kfree(store->context);
}

static int transient_read_metadata(struct dm_exception_store *store,
				   int (*callback)(void *callback_context,
						   chunk_t old, chunk_t new),
				   void *callback_context)
{
	return 0;
}

static int transient_prepare_exception(struct dm_exception_store *store,
				       struct dm_snap_exception *e)
{
	struct transient_c *tc = store->context;
	sector_t size = get_dev_size(store->cow->bdev);

	if (size < (tc->next_free + store->chunk_size))
		return -1;

	e->new_chunk = sector_to_chunk(store, tc->next_free);
	tc->next_free += store->chunk_size;

	return 0;
}

static void transient_commit_exception(struct dm_exception_store *store,
				       struct dm_snap_exception *e,
				       void (*callback) (void *, int success),
				       void *callback_context)
{
	/* Just succeed */
	callback(callback_context, 1);
}

static void transient_fraction_full(struct dm_exception_store *store,
				    sector_t *numerator, sector_t *denominator)
{
	*numerator = ((struct transient_c *) store->context)->next_free;
	*denominator = get_dev_size(store->cow->bdev);
}

static int transient_ctr(struct dm_exception_store *store,
			 unsigned argc, char **argv)
{
	struct transient_c *tc;

	tc = kmalloc(sizeof(struct transient_c), GFP_KERNEL);
	if (!tc)
		return -ENOMEM;

	tc->next_free = 0;
	store->context = tc;

	return 0;
}

static unsigned transient_status(struct dm_exception_store *store,
				 status_type_t status, char *result,
				 unsigned maxlen)
{
	unsigned sz = 0;

	switch (status) {
	case STATUSTYPE_INFO:
		break;
	case STATUSTYPE_TABLE:
		DMEMIT(" %s N %llu", store->cow->name,
		       (unsigned long long)store->chunk_size);
	}

	return sz;
}

static struct dm_exception_store_type _transient_type = {
	.name = "transient",
	.module = THIS_MODULE,
	.ctr = transient_ctr,
	.dtr = transient_dtr,
	.read_metadata = transient_read_metadata,
	.prepare_exception = transient_prepare_exception,
	.commit_exception = transient_commit_exception,
	.fraction_full = transient_fraction_full,
	.status = transient_status,
};

static struct dm_exception_store_type _transient_compat_type = {
	.name = "N",
	.module = THIS_MODULE,
	.ctr = transient_ctr,
	.dtr = transient_dtr,
	.read_metadata = transient_read_metadata,
	.prepare_exception = transient_prepare_exception,
	.commit_exception = transient_commit_exception,
	.fraction_full = transient_fraction_full,
	.status = transient_status,
};

int dm_transient_snapshot_init(void)
{
	int r;

	r = dm_exception_store_type_register(&_transient_type);
	if (r) {
		DMWARN("Unable to register transient exception store type");
		return r;
	}

	r = dm_exception_store_type_register(&_transient_compat_type);
	if (r) {
		DMWARN("Unable to register old-style transient "
		       "exception store type");
		dm_exception_store_type_unregister(&_transient_type);
		return r;
	}

	return r;
}

void dm_transient_snapshot_exit(void)
{
	dm_exception_store_type_unregister(&_transient_type);
	dm_exception_store_type_unregister(&_transient_compat_type);
}