Root/drivers/md/dm-thin-metadata.h

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                           bool format_device);
43
44int dm_pool_metadata_close(struct dm_pool_metadata *pmd);
45
46/*
47 * Compat feature flags. Any incompat flags beyond the ones
48 * specified below will prevent use of the thin metadata.
49 */
50#define THIN_FEATURE_COMPAT_SUPP 0UL
51#define THIN_FEATURE_COMPAT_RO_SUPP 0UL
52#define THIN_FEATURE_INCOMPAT_SUPP 0UL
53
54/*
55 * Device creation/deletion.
56 */
57int dm_pool_create_thin(struct dm_pool_metadata *pmd, dm_thin_id dev);
58
59/*
60 * An internal snapshot.
61 *
62 * You can only snapshot a quiesced origin i.e. one that is either
63 * suspended or not instanced at all.
64 */
65int dm_pool_create_snap(struct dm_pool_metadata *pmd, dm_thin_id dev,
66            dm_thin_id origin);
67
68/*
69 * Deletes a virtual device from the metadata. It _is_ safe to call this
70 * when that device is open. Operations on that device will just start
71 * failing. You still need to call close() on the device.
72 */
73int dm_pool_delete_thin_device(struct dm_pool_metadata *pmd,
74                   dm_thin_id dev);
75
76/*
77 * Commits _all_ metadata changes: device creation, deletion, mapping
78 * updates.
79 */
80int dm_pool_commit_metadata(struct dm_pool_metadata *pmd);
81
82/*
83 * Discards all uncommitted changes. Rereads the superblock, rolling back
84 * to the last good transaction. Thin devices remain open.
85 * dm_thin_aborted_changes() tells you if they had uncommitted changes.
86 *
87 * If this call fails it's only useful to call dm_pool_metadata_close().
88 * All other methods will fail with -EINVAL.
89 */
90int dm_pool_abort_metadata(struct dm_pool_metadata *pmd);
91
92/*
93 * Set/get userspace transaction id.
94 */
95int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
96                    uint64_t current_id,
97                    uint64_t new_id);
98
99int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
100                    uint64_t *result);
101
102/*
103 * Hold/get root for userspace transaction.
104 *
105 * The metadata snapshot is a copy of the current superblock (minus the
106 * space maps). Userland can access the data structures for READ
107 * operations only. A small performance hit is incurred by providing this
108 * copy of the metadata to userland due to extra copy-on-write operations
109 * on the metadata nodes. Release this as soon as you finish with it.
110 */
111int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd);
112int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd);
113
114int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd,
115                  dm_block_t *result);
116
117/*
118 * Actions on a single virtual device.
119 */
120
121/*
122 * Opening the same device more than once will fail with -EBUSY.
123 */
124int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
125                 struct dm_thin_device **td);
126
127int dm_pool_close_thin_device(struct dm_thin_device *td);
128
129dm_thin_id dm_thin_dev_id(struct dm_thin_device *td);
130
131struct dm_thin_lookup_result {
132    dm_block_t block;
133    unsigned shared:1;
134};
135
136/*
137 * Returns:
138 * -EWOULDBLOCK iff @can_block is set and would block.
139 * -ENODATA iff that mapping is not present.
140 * 0 success
141 */
142int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
143               int can_block, struct dm_thin_lookup_result *result);
144
145/*
146 * Obtain an unused block.
147 */
148int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result);
149
150/*
151 * Insert or remove block.
152 */
153int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
154             dm_block_t data_block);
155
156int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block);
157
158/*
159 * Queries.
160 */
161bool dm_thin_changed_this_transaction(struct dm_thin_device *td);
162
163bool dm_thin_aborted_changes(struct dm_thin_device *td);
164
165int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
166                     dm_block_t *highest_mapped);
167
168int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result);
169
170int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd,
171                 dm_block_t *result);
172
173int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
174                      dm_block_t *result);
175
176int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
177                  dm_block_t *result);
178
179int dm_pool_get_data_block_size(struct dm_pool_metadata *pmd, sector_t *result);
180
181int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result);
182
183/*
184 * Returns -ENOSPC if the new size is too small and already allocated
185 * blocks would be lost.
186 */
187int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
188
189/*
190 * Flicks the underlying block manager into read only mode, so you know
191 * that nothing is changing.
192 */
193void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd);
194
195/*----------------------------------------------------------------*/
196
197#endif
198

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