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 #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 struct dm_pool_metadata;
  29 struct dm_thin_device;
  30
  31 /*
  32  * Device identifier
  33  */
  34 typedef uint64_t dm_thin_id;
  35
  36 /*
  37  * Reopens or creates a new, empty metadata volume.
  38  */
  39 struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
  40                                                sector_t data_block_size,
  41                                                bool format_device);
  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  * Discards all uncommitted changes.  Rereads the superblock, rolling back
  83  * to the last good transaction.  Thin devices remain open.
  84  * dm_thin_aborted_changes() tells you if they had uncommitted changes.
  85  *
  86  * If this call fails it's only useful to call dm_pool_metadata_close().
  87  * All other methods will fail with -EINVAL.
  88  */
  89 int dm_pool_abort_metadata(struct dm_pool_metadata *pmd);
  90
  91 /*
  92  * Set/get userspace transaction id.
  93  */
  94 int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
  95                                         uint64_t current_id,
  96                                         uint64_t new_id);
  97
  98 int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
  99                                         uint64_t *result);
 100
 101 /*
 102  * Hold/get root for userspace transaction.
 103  *
 104  * The metadata snapshot is a copy of the current superblock (minus the
 105  * space maps).  Userland can access the data structures for READ
 106  * operations only.  A small performance hit is incurred by providing this
 107  * copy of the metadata to userland due to extra copy-on-write operations
 108  * on the metadata nodes.  Release this as soon as you finish with it.
 109  */
 110 int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd);
 111 int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd);
 112
 113 int dm_pool_get_metadata_snap(struct dm_pool_metadata *pmd,
 114                               dm_block_t *result);
 115
 116 /*
 117  * Actions on a single virtual device.
 118  */
 119
 120 /*
 121  * Opening the same device more than once will fail with -EBUSY.
 122  */
 123 int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
 124                              struct dm_thin_device **td);
 125
 126 int dm_pool_close_thin_device(struct dm_thin_device *td);
 127
 128 dm_thin_id dm_thin_dev_id(struct dm_thin_device *td);
 129
 130 struct dm_thin_lookup_result {
 131         dm_block_t block;
 132         bool shared:1;
 133 };
 134
 135 /*
 136  * Returns:
 137  *   -EWOULDBLOCK iff @can_block is set and would block.
 138  *   -ENODATA iff that mapping is not present.
 139  *   0 success
 140  */
 141 int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
 142                        int can_block, struct dm_thin_lookup_result *result);
 143
 144 /*
 145  * Obtain an unused block.
 146  */
 147 int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result);
 148
 149 /*
 150  * Insert or remove block.
 151  */
 152 int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
 153                          dm_block_t data_block);
 154
 155 int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block);
 156
 157 /*
 158  * Queries.
 159  */
 160 bool dm_thin_changed_this_transaction(struct dm_thin_device *td);
 161
 162 bool dm_pool_changed_this_transaction(struct dm_pool_metadata *pmd);
 163
 164 bool dm_thin_aborted_changes(struct dm_thin_device *td);
 165
 166 int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
 167                                      dm_block_t *highest_mapped);
 168
 169 int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result);
 170
 171 int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd,
 172                                  dm_block_t *result);
 173
 174 int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
 175                                           dm_block_t *result);
 176
 177 int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
 178                                   dm_block_t *result);
 179
 180 int dm_pool_get_data_block_size(struct dm_pool_metadata *pmd, sector_t *result);
 181
 182 int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result);
 183
 184 int dm_pool_block_is_used(struct dm_pool_metadata *pmd, dm_block_t b, bool *result);
 185
 186 /*
 187  * Returns -ENOSPC if the new size is too small and already allocated
 188  * blocks would be lost.
 189  */
 190 int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
 191 int dm_pool_resize_metadata_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
 192
 193 /*
 194  * Flicks the underlying block manager into read only mode, so you know
 195  * that nothing is changing.
 196  */
 197 void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd);
 198 void dm_pool_metadata_read_write(struct dm_pool_metadata *pmd);
 199
 200 int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
 201                                         dm_block_t threshold,
 202                                         dm_sm_threshold_fn fn,
 203                                         void *context);
 204
 205 /*----------------------------------------------------------------*/
 206
 207 #endif