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
  29 struct dm_pool_metadata;
  30 struct dm_thin_device;
  31
  32 /*
  33  * Device identifier
  34  */
  35 typedef uint64_t dm_thin_id;
  36
  37 /*
  38  * Reopens or creates a new, empty metadata volume.
  39  */
  40 struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
  41                                                sector_t data_block_size,
  42                                                bool format_device);
  43
  44 int 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  */
  57 int 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  */
  65 int 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  */
  73 int 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  */
  80 int dm_pool_commit_metadata(struct dm_pool_metadata *pmd);
  81
  82 /*
  83  * Set/get userspace transaction id.
  84  */
  85 int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
  86                                         uint64_t current_id,
  87                                         uint64_t new_id);
  88
  89 int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
  90                                         uint64_t *result);
  91
  92 /*
  93  * Hold/get root for userspace transaction.
  94  *
  95  * The metadata snapshot is a copy of the current superblock (minus the
  96  * space maps).  Userland can access the data structures for READ
  97  * operations only.  A small performance hit is incurred by providing this
  98  * copy of the metadata to userland due to extra copy-on-write operations
  99  * on the metadata nodes.  Release this as soon as you finish with it.
 100  */
 101 int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd);
 102 int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd);
 103
 104 int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd,
 105                               dm_block_t *result);
 106
 107 /*
 108  * Actions on a single virtual device.
 109  */
 110
 111 /*
 112  * Opening the same device more than once will fail with -EBUSY.
 113  */
 114 int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
 115                              struct dm_thin_device **td);
 116
 117 int dm_pool_close_thin_device(struct dm_thin_device *td);
 118
 119 dm_thin_id dm_thin_dev_id(struct dm_thin_device *td);
 120
 121 struct dm_thin_lookup_result {
 122         dm_block_t block;
 123         unsigned shared:1;
 124 };
 125
 126 /*
 127  * Returns:
 128  *   -EWOULDBLOCK iff @can_block is set and would block.
 129  *   -ENODATA iff that mapping is not present.
 130  *   0 success
 131  */
 132 int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
 133                        int can_block, struct dm_thin_lookup_result *result);
 134
 135 /*
 136  * Obtain an unused block.
 137  */
 138 int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result);
 139
 140 /*
 141  * Insert or remove block.
 142  */
 143 int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
 144                          dm_block_t data_block);
 145
 146 int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block);
 147
 148 /*
 149  * Queries.
 150  */
 151 int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
 152                                      dm_block_t *highest_mapped);
 153
 154 int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result);
 155
 156 int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd,
 157                                  dm_block_t *result);
 158
 159 int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
 160                                           dm_block_t *result);
 161
 162 int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
 163                                   dm_block_t *result);
 164
 165 int dm_pool_get_data_block_size(struct dm_pool_metadata *pmd, sector_t *result);
 166
 167 int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result);
 168
 169 /*
 170  * Returns -ENOSPC if the new size is too small and already allocated
 171  * blocks would be lost.
 172  */
 173 int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
 174
 175 /*----------------------------------------------------------------*/
 176
 177 #endif