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#include "persistent-data/dm-space-map-metadata.h"
  13
  14#define THIN_METADATA_BLOCK_SIZE DM_SM_METADATA_BLOCK_SIZE
  15
  16/*
  17 * The metadata device is currently limited in size.
  18 */
  19#define THIN_METADATA_MAX_SECTORS DM_SM_METADATA_MAX_SECTORS
  20
  21/*
  22 * A metadata device larger than 16GB triggers a warning.
  23 */
  24#define THIN_METADATA_MAX_SECTORS_WARNING (16 * (1024 * 1024 * 1024 >> SECTOR_SHIFT))
  25
  26/*----------------------------------------------------------------*/
  27
  28/*
  29 * Thin metadata superblock flags.
  30 */
  31#define THIN_METADATA_NEEDS_CHECK_FLAG (1 << 0)
  32
  33struct dm_pool_metadata;
  34struct dm_thin_device;
  35
  36/*
  37 * Device identifier
  38 */
  39typedef uint64_t dm_thin_id;
  40
  41/*
  42 * Reopens or creates a new, empty metadata volume.
  43 */
  44struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
  45                                               sector_t data_block_size,
  46                                               bool format_device);
  47
  48int dm_pool_metadata_close(struct dm_pool_metadata *pmd);
  49
  50/*
  51 * Compat feature flags.  Any incompat flags beyond the ones
  52 * specified below will prevent use of the thin metadata.
  53 */
  54#define THIN_FEATURE_COMPAT_SUPP          0UL
  55#define THIN_FEATURE_COMPAT_RO_SUPP       0UL
  56#define THIN_FEATURE_INCOMPAT_SUPP        0UL
  57
  58/*
  59 * Device creation/deletion.
  60 */
  61int dm_pool_create_thin(struct dm_pool_metadata *pmd, dm_thin_id dev);
  62
  63/*
  64 * An internal snapshot.
  65 *
  66 * You can only snapshot a quiesced origin i.e. one that is either
  67 * suspended or not instanced at all.
  68 */
  69int dm_pool_create_snap(struct dm_pool_metadata *pmd, dm_thin_id dev,
  70                        dm_thin_id origin);
  71
  72/*
  73 * Deletes a virtual device from the metadata.  It _is_ safe to call this
  74 * when that device is open.  Operations on that device will just start
  75 * failing.  You still need to call close() on the device.
  76 */
  77int dm_pool_delete_thin_device(struct dm_pool_metadata *pmd,
  78                               dm_thin_id dev);
  79
  80/*
  81 * Commits _all_ metadata changes: device creation, deletion, mapping
  82 * updates.
  83 */
  84int dm_pool_commit_metadata(struct dm_pool_metadata *pmd);
  85
  86/*
  87 * Discards all uncommitted changes.  Rereads the superblock, rolling back
  88 * to the last good transaction.  Thin devices remain open.
  89 * dm_thin_aborted_changes() tells you if they had uncommitted changes.
  90 *
  91 * If this call fails it's only useful to call dm_pool_metadata_close().
  92 * All other methods will fail with -EINVAL.
  93 */
  94int dm_pool_abort_metadata(struct dm_pool_metadata *pmd);
  95
  96/*
  97 * Set/get userspace transaction id.
  98 */
  99int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
 100                                        uint64_t current_id,
 101                                        uint64_t new_id);
 102
 103int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
 104                                        uint64_t *result);
 105
 106/*
 107 * Hold/get root for userspace transaction.
 108 *
 109 * The metadata snapshot is a copy of the current superblock (minus the
 110 * space maps).  Userland can access the data structures for READ
 111 * operations only.  A small performance hit is incurred by providing this
 112 * copy of the metadata to userland due to extra copy-on-write operations
 113 * on the metadata nodes.  Release this as soon as you finish with it.
 114 */
 115int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd);
 116int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd);
 117
 118int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd,
 119                              dm_block_t *result);
 120
 121/*
 122 * Actions on a single virtual device.
 123 */
 124
 125/*
 126 * Opening the same device more than once will fail with -EBUSY.
 127 */
 128int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
 129                             struct dm_thin_device **td);
 130
 131int dm_pool_close_thin_device(struct dm_thin_device *td);
 132
 133dm_thin_id dm_thin_dev_id(struct dm_thin_device *td);
 134
 135struct dm_thin_lookup_result {
 136        dm_block_t block;
 137        bool shared:1;
 138};
 139
 140/*
 141 * Returns:
 142 *   -EWOULDBLOCK iff @can_issue_io is set and would issue IO
 143 *   -ENODATA iff that mapping is not present.
 144 *   0 success
 145 */
 146int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
 147                       int can_issue_io, struct dm_thin_lookup_result *result);
 148
 149/*
 150 * Retrieve the next run of contiguously mapped blocks.  Useful for working
 151 * out where to break up IO.  Returns 0 on success, < 0 on error.
 152 */
 153int dm_thin_find_mapped_range(struct dm_thin_device *td,
 154                              dm_block_t begin, dm_block_t end,
 155                              dm_block_t *thin_begin, dm_block_t *thin_end,
 156                              dm_block_t *pool_begin, bool *maybe_shared);
 157
 158/*
 159 * Obtain an unused block.
 160 */
 161int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result);
 162
 163/*
 164 * Insert or remove block.
 165 */
 166int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
 167                         dm_block_t data_block);
 168
 169int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block);
 170int dm_thin_remove_range(struct dm_thin_device *td,
 171                         dm_block_t begin, dm_block_t end);
 172
 173/*
 174 * Queries.
 175 */
 176bool dm_thin_changed_this_transaction(struct dm_thin_device *td);
 177
 178bool dm_pool_changed_this_transaction(struct dm_pool_metadata *pmd);
 179
 180bool dm_thin_aborted_changes(struct dm_thin_device *td);
 181
 182int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
 183                                     dm_block_t *highest_mapped);
 184
 185int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result);
 186
 187int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd,
 188                                 dm_block_t *result);
 189
 190int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
 191                                          dm_block_t *result);
 192
 193int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
 194                                  dm_block_t *result);
 195
 196int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result);
 197
 198int dm_pool_block_is_shared(struct dm_pool_metadata *pmd, dm_block_t b, bool *result);
 199
 200int dm_pool_inc_data_range(struct dm_pool_metadata *pmd, dm_block_t b, dm_block_t e);
 201int dm_pool_dec_data_range(struct dm_pool_metadata *pmd, dm_block_t b, dm_block_t e);
 202
 203/*
 204 * Returns -ENOSPC if the new size is too small and already allocated
 205 * blocks would be lost.
 206 */
 207int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
 208int dm_pool_resize_metadata_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
 209
 210/*
 211 * Flicks the underlying block manager into read only mode, so you know
 212 * that nothing is changing.
 213 */
 214void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd);
 215void dm_pool_metadata_read_write(struct dm_pool_metadata *pmd);
 216
 217int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
 218                                        dm_block_t threshold,
 219                                        dm_sm_threshold_fn fn,
 220                                        void *context);
 221
 222/*
 223 * Updates the superblock immediately.
 224 */
 225int dm_pool_metadata_set_needs_check(struct dm_pool_metadata *pmd);
 226bool dm_pool_metadata_needs_check(struct dm_pool_metadata *pmd);
 227
 228/*
 229 * Issue any prefetches that may be useful.
 230 */
 231void dm_pool_issue_prefetches(struct dm_pool_metadata *pmd);
 232
 233/* Pre-commit callback */
 234typedef int (*dm_pool_pre_commit_fn)(void *context);
 235
 236void dm_pool_register_pre_commit_callback(struct dm_pool_metadata *pmd,
 237                                          dm_pool_pre_commit_fn fn,
 238                                          void *context);
 239
 240/*----------------------------------------------------------------*/
 241
 242#endif
 243