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
  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
  30 struct dm_pool_metadata;
  31 struct dm_thin_device;
  32
  33 /*
  34  * Device identifier
  35  */
  36 typedef uint64_t dm_thin_id;
  37
  38 /*
  39  * Reopens or creates a new, empty metadata volume.
  40  */
  41 struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
  42                                                sector_t data_block_size,
  43                                                bool format_device);
  44
  45 int 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  */
  58 int 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  */
  66 int 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  */
  74 int 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  */
  81 int 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  */
  91 int dm_pool_abort_metadata(struct dm_pool_metadata *pmd);
  92
  93 /*
  94  * Set/get userspace transaction id.
  95  */
  96 int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
  97                                         uint64_t current_id,
  98                                         uint64_t new_id);
  99
 100 int 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  */
 112 int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd);
 113 int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd);
 114
 115 int 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  */
 125 int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
 126                              struct dm_thin_device **td);
 127
 128 int dm_pool_close_thin_device(struct dm_thin_device *td);
 129
 130 dm_thin_id dm_thin_dev_id(struct dm_thin_device *td);
 131
 132 struct 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  */
 143 int 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  */
 149 int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result);
 150
 151 /*
 152  * Insert or remove block.
 153  */
 154 int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
 155                          dm_block_t data_block);
 156
 157 int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block);
 158
 159 /*
 160  * Queries.
 161  */
 162 bool dm_thin_changed_this_transaction(struct dm_thin_device *td);
 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 /*
 185  * Returns -ENOSPC if the new size is too small and already allocated
 186  * blocks would be lost.
 187  */
 188 int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
 189 int 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  */
 195 void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd);
 196
 197 int 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