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
  43 int dm_pool_metadata_close(struct dm_pool_metadata *pmd);
  44
  45 /*
  46  * Compat feature flags.  Any incompat flags beyond the ones
  47  * specified below will prevent use of the thin metadata.
  48  */
  49 #define THIN_FEATURE_COMPAT_SUPP          0UL
  50 #define THIN_FEATURE_COMPAT_RO_SUPP       0UL
  51 #define THIN_FEATURE_INCOMPAT_SUPP        0UL
  52
  53 /*
  54  * Device creation/deletion.
  55  */
  56 int dm_pool_create_thin(struct dm_pool_metadata *pmd, dm_thin_id dev);
  57
  58 /*
  59  * An internal snapshot.
  60  *
  61  * You can only snapshot a quiesced origin i.e. one that is either
  62  * suspended or not instanced at all.
  63  */
  64 int dm_pool_create_snap(struct dm_pool_metadata *pmd, dm_thin_id dev,
  65                         dm_thin_id origin);
  66
  67 /*
  68  * Deletes a virtual device from the metadata.  It _is_ safe to call this
  69  * when that device is open.  Operations on that device will just start
  70  * failing.  You still need to call close() on the device.
  71  */
  72 int dm_pool_delete_thin_device(struct dm_pool_metadata *pmd,
  73                                dm_thin_id dev);
  74
  75 /*
  76  * Commits _all_ metadata changes: device creation, deletion, mapping
  77  * updates.
  78  */
  79 int dm_pool_commit_metadata(struct dm_pool_metadata *pmd);
  80
  81 /*
  82  * Set/get userspace transaction id.
  83  */
  84 int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
  85                                         uint64_t current_id,
  86                                         uint64_t new_id);
  87
  88 int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
  89                                         uint64_t *result);
  90
  91 /*
  92  * Hold/get root for userspace transaction.
  93  *
  94  * The metadata snapshot is a copy of the current superblock (minus the
  95  * space maps).  Userland can access the data structures for READ
  96  * operations only.  A small performance hit is incurred by providing this
  97  * copy of the metadata to userland due to extra copy-on-write operations
  98  * on the metadata nodes.  Release this as soon as you finish with it.
  99  */
 100 int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd);
 101 int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd);
 102
 103 int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd,
 104                               dm_block_t *result);
 105
 106 /*
 107  * Actions on a single virtual device.
 108  */
 109
 110 /*
 111  * Opening the same device more than once will fail with -EBUSY.
 112  */
 113 int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
 114                              struct dm_thin_device **td);
 115
 116 int dm_pool_close_thin_device(struct dm_thin_device *td);
 117
 118 dm_thin_id dm_thin_dev_id(struct dm_thin_device *td);
 119
 120 struct dm_thin_lookup_result {
 121         dm_block_t block;
 122         int shared;
 123 };
 124
 125 /*
 126  * Returns:
 127  *   -EWOULDBLOCK iff @can_block is set and would block.
 128  *   -ENODATA iff that mapping is not present.
 129  *   0 success
 130  */
 131 int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
 132                        int can_block, struct dm_thin_lookup_result *result);
 133
 134 /*
 135  * Obtain an unused block.
 136  */
 137 int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result);
 138
 139 /*
 140  * Insert or remove block.
 141  */
 142 int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
 143                          dm_block_t data_block);
 144
 145 int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block);
 146
 147 /*
 148  * Queries.
 149  */
 150 int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
 151                                      dm_block_t *highest_mapped);
 152
 153 int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result);
 154
 155 int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd,
 156                                  dm_block_t *result);
 157
 158 int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
 159                                           dm_block_t *result);
 160
 161 int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
 162                                   dm_block_t *result);
 163
 164 int dm_pool_get_data_block_size(struct dm_pool_metadata *pmd, sector_t *result);
 165
 166 int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result);
 167
 168 /*
 169  * Returns -ENOSPC if the new size is too small and already allocated
 170  * blocks would be lost.
 171  */
 172 int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
 173
 174 /*----------------------------------------------------------------*/
 175
 176 #endif