tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1/*
2 * Copyright (C) 2010-2011 Red Hat, Inc.
3 *
4 * This file is released under the GPL.
5 */
6
7#ifndef DM_THIN_METADATA_H
8#define DM_THIN_METADATA_H
9
10#include "persistent-data/dm-block-manager.h"
11
12#define THIN_METADATA_BLOCK_SIZE 4096
13
14/*
15 * The metadata device is currently limited in size.
16 *
17 * We have one block of index, which can hold 255 index entries. Each
18 * index entry contains allocation info about 16k metadata blocks.
19 */
20#define THIN_METADATA_MAX_SECTORS (255 * (1 << 14) * (THIN_METADATA_BLOCK_SIZE / (1 << SECTOR_SHIFT)))
21
22/*
23 * A metadata device larger than 16GB triggers a warning.
24 */
25#define THIN_METADATA_MAX_SECTORS_WARNING (16 * (1024 * 1024 * 1024 >> SECTOR_SHIFT))
26
27/*----------------------------------------------------------------*/
28
29struct dm_pool_metadata;
30struct dm_thin_device;
31
32/*
33 * Device identifier
34 */
35typedef uint64_t dm_thin_id;
36
37/*
38 * Reopens or creates a new, empty metadata volume.
39 */
40struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
41 sector_t data_block_size);
42
43int dm_pool_metadata_close(struct dm_pool_metadata *pmd);
44
45/*
46 * Compat feature flags. Any incompat flags beyond the ones
47 * specified below will prevent use of the thin metadata.
48 */
49#define THIN_FEATURE_COMPAT_SUPP 0UL
50#define THIN_FEATURE_COMPAT_RO_SUPP 0UL
51#define THIN_FEATURE_INCOMPAT_SUPP 0UL
52
53/*
54 * Device creation/deletion.
55 */
56int dm_pool_create_thin(struct dm_pool_metadata *pmd, dm_thin_id dev);
57
58/*
59 * An internal snapshot.
60 *
61 * You can only snapshot a quiesced origin i.e. one that is either
62 * suspended or not instanced at all.
63 */
64int dm_pool_create_snap(struct dm_pool_metadata *pmd, dm_thin_id dev,
65 dm_thin_id origin);
66
67/*
68 * Deletes a virtual device from the metadata. It _is_ safe to call this
69 * when that device is open. Operations on that device will just start
70 * failing. You still need to call close() on the device.
71 */
72int dm_pool_delete_thin_device(struct dm_pool_metadata *pmd,
73 dm_thin_id dev);
74
75/*
76 * Commits _all_ metadata changes: device creation, deletion, mapping
77 * updates.
78 */
79int dm_pool_commit_metadata(struct dm_pool_metadata *pmd);
80
81/*
82 * Set/get userspace transaction id.
83 */
84int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
85 uint64_t current_id,
86 uint64_t new_id);
87
88int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
89 uint64_t *result);
90
91/*
92 * Hold/get root for userspace transaction.
93 *
94 * The metadata snapshot is a copy of the current superblock (minus the
95 * space maps). Userland can access the data structures for READ
96 * operations only. A small performance hit is incurred by providing this
97 * copy of the metadata to userland due to extra copy-on-write operations
98 * on the metadata nodes. Release this as soon as you finish with it.
99 */
100int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd);
101int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd);
102
103int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd,
104 dm_block_t *result);
105
106/*
107 * Actions on a single virtual device.
108 */
109
110/*
111 * Opening the same device more than once will fail with -EBUSY.
112 */
113int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
114 struct dm_thin_device **td);
115
116int dm_pool_close_thin_device(struct dm_thin_device *td);
117
118dm_thin_id dm_thin_dev_id(struct dm_thin_device *td);
119
120struct dm_thin_lookup_result {
121 dm_block_t block;
122 int shared;
123};
124
125/*
126 * Returns:
127 * -EWOULDBLOCK iff @can_block is set and would block.
128 * -ENODATA iff that mapping is not present.
129 * 0 success
130 */
131int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
132 int can_block, struct dm_thin_lookup_result *result);
133
134/*
135 * Obtain an unused block.
136 */
137int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result);
138
139/*
140 * Insert or remove block.
141 */
142int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
143 dm_block_t data_block);
144
145int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block);
146
147/*
148 * Queries.
149 */
150int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
151 dm_block_t *highest_mapped);
152
153int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result);
154
155int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd,
156 dm_block_t *result);
157
158int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
159 dm_block_t *result);
160
161int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
162 dm_block_t *result);
163
164int dm_pool_get_data_block_size(struct dm_pool_metadata *pmd, sector_t *result);
165
166int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result);
167
168/*
169 * Returns -ENOSPC if the new size is too small and already allocated
170 * blocks would be lost.
171 */
172int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
173
174/*----------------------------------------------------------------*/
175
176#endif