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/export.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 *---------------------------------------------------------------*/
22struct transient_c {
23	sector_t next_free;
24};
25
26static void transient_dtr(struct dm_exception_store *store)
27{
28	kfree(store->context);
29}
30
31static 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
39static int transient_prepare_exception(struct dm_exception_store *store,
40				       struct dm_exception *e)
41{
42	struct transient_c *tc = store->context;
43	sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev);
44
45	if (size < (tc->next_free + store->chunk_size))
46		return -1;
47
48	e->new_chunk = sector_to_chunk(store, tc->next_free);
49	tc->next_free += store->chunk_size;
50
51	return 0;
52}
53
54static void transient_commit_exception(struct dm_exception_store *store,
55				       struct dm_exception *e, int valid,
56				       void (*callback) (void *, int success),
57				       void *callback_context)
58{
59	/* Just succeed */
60	callback(callback_context, valid);
61}
62
63static void transient_usage(struct dm_exception_store *store,
64			    sector_t *total_sectors,
65			    sector_t *sectors_allocated,
66			    sector_t *metadata_sectors)
67{
68	*sectors_allocated = ((struct transient_c *) store->context)->next_free;
69	*total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev);
70	*metadata_sectors = 0;
71}
72
73static int transient_ctr(struct dm_exception_store *store, char *options)
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
87static 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
103static 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
115static 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
127int 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
148void 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