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#include "persistent-data/dm-space-map.h"
  12
  13#define THIN_METADATA_BLOCK_SIZE 4096
  14
  15/*
  16 * The metadata device is currently limited in size.
  17 *
  18 * We have one block of index, which can hold 255 index entries.  Each
  19 * index entry contains allocation info about 16k metadata blocks.
  20 */
  21#define THIN_METADATA_MAX_SECTORS (255 * (1 << 14) * (THIN_METADATA_BLOCK_SIZE / (1 << SECTOR_SHIFT)))
  22
  23/*
  24 * A metadata device larger than 16GB triggers a warning.
  25 */
  26#define THIN_METADATA_MAX_SECTORS_WARNING (16 * (1024 * 1024 * 1024 >> SECTOR_SHIFT))
  27
  28/*----------------------------------------------------------------*/
  29
  30struct dm_pool_metadata;
  31struct dm_thin_device;
  32
  33/*
  34 * Device identifier
  35 */
  36typedef uint64_t dm_thin_id;
  37
  38/*
  39 * Reopens or creates a new, empty metadata volume.
  40 */
  41struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
  42                                               sector_t data_block_size,
  43                                               bool format_device);
  44
  45int dm_pool_metadata_close(struct dm_pool_metadata *pmd);
  46
  47/*
  48 * Compat feature flags.  Any incompat flags beyond the ones
  49 * specified below will prevent use of the thin metadata.
  50 */
  51#define THIN_FEATURE_COMPAT_SUPP          0UL
  52#define THIN_FEATURE_COMPAT_RO_SUPP       0UL
  53#define THIN_FEATURE_INCOMPAT_SUPP        0UL
  54
  55/*
  56 * Device creation/deletion.
  57 */
  58int dm_pool_create_thin(struct dm_pool_metadata *pmd, dm_thin_id dev);
  59
  60/*
  61 * An internal snapshot.
  62 *
  63 * You can only snapshot a quiesced origin i.e. one that is either
  64 * suspended or not instanced at all.
  65 */
  66int dm_pool_create_snap(struct dm_pool_metadata *pmd, dm_thin_id dev,
  67                        dm_thin_id origin);
  68
  69/*
  70 * Deletes a virtual device from the metadata.  It _is_ safe to call this
  71 * when that device is open.  Operations on that device will just start
  72 * failing.  You still need to call close() on the device.
  73 */
  74int dm_pool_delete_thin_device(struct dm_pool_metadata *pmd,
  75                               dm_thin_id dev);
  76
  77/*
  78 * Commits _all_ metadata changes: device creation, deletion, mapping
  79 * updates.
  80 */
  81int dm_pool_commit_metadata(struct dm_pool_metadata *pmd);
  82
  83/*
  84 * Discards all uncommitted changes.  Rereads the superblock, rolling back
  85 * to the last good transaction.  Thin devices remain open.
  86 * dm_thin_aborted_changes() tells you if they had uncommitted changes.
  87 *
  88 * If this call fails it's only useful to call dm_pool_metadata_close().
  89 * All other methods will fail with -EINVAL.
  90 */
  91int dm_pool_abort_metadata(struct dm_pool_metadata *pmd);
  92
  93/*
  94 * Set/get userspace transaction id.
  95 */
  96int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
  97                                        uint64_t current_id,
  98                                        uint64_t new_id);
  99
 100int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
 101                                        uint64_t *result);
 102
 103/*
 104 * Hold/get root for userspace transaction.
 105 *
 106 * The metadata snapshot is a copy of the current superblock (minus the
 107 * space maps).  Userland can access the data structures for READ
 108 * operations only.  A small performance hit is incurred by providing this
 109 * copy of the metadata to userland due to extra copy-on-write operations
 110 * on the metadata nodes.  Release this as soon as you finish with it.
 111 */
 112int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd);
 113int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd);
 114
 115int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd,
 116                              dm_block_t *result);
 117
 118/*
 119 * Actions on a single virtual device.
 120 */
 121
 122/*
 123 * Opening the same device more than once will fail with -EBUSY.
 124 */
 125int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
 126                             struct dm_thin_device **td);
 127
 128int dm_pool_close_thin_device(struct dm_thin_device *td);
 129
 130dm_thin_id dm_thin_dev_id(struct dm_thin_device *td);
 131
 132struct dm_thin_lookup_result {
 133        dm_block_t block;
 134        unsigned shared:1;
 135};
 136
 137/*
 138 * Returns:
 139 *   -EWOULDBLOCK iff @can_block is set and would block.
 140 *   -ENODATA iff that mapping is not present.
 141 *   0 success
 142 */
 143int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
 144                       int can_block, struct dm_thin_lookup_result *result);
 145
 146/*
 147 * Obtain an unused block.
 148 */
 149int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result);
 150
 151/*
 152 * Insert or remove block.
 153 */
 154int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
 155                         dm_block_t data_block);
 156
 157int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block);
 158
 159/*
 160 * Queries.
 161 */
 162bool dm_thin_changed_this_transaction(struct dm_thin_device *td);
 163
 164bool dm_thin_aborted_changes(struct dm_thin_device *td);
 165
 166int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
 167                                     dm_block_t *highest_mapped);
 168
 169int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result);
 170
 171int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd,
 172                                 dm_block_t *result);
 173
 174int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
 175                                          dm_block_t *result);
 176
 177int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
 178                                  dm_block_t *result);
 179
 180int dm_pool_get_data_block_size(struct dm_pool_metadata *pmd, sector_t *result);
 181
 182int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result);
 183
 184/*
 185 * Returns -ENOSPC if the new size is too small and already allocated
 186 * blocks would be lost.
 187 */
 188int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
 189int dm_pool_resize_metadata_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
 190
 191/*
 192 * Flicks the underlying block manager into read only mode, so you know
 193 * that nothing is changing.
 194 */
 195void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd);
 196
 197int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
 198                                        dm_block_t threshold,
 199                                        dm_sm_threshold_fn fn,
 200                                        void *context);
 201
 202/*----------------------------------------------------------------*/
 203
 204#endif
 205
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