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