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 /*
  29  * Thin metadata superblock flags.
  30  */
  31 #define THIN_METADATA_NEEDS_CHECK_FLAG (1 << 0)
  32
  33 struct dm_pool_metadata;
  34 struct dm_thin_device;
  35
  36 /*
  37  * Device identifier
  38  */
  39 typedef uint64_t dm_thin_id;
  40
  41 /*
  42  * Reopens or creates a new, empty metadata volume.
  43  */
  44 struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
  45                                                sector_t data_block_size,
  46                                                bool format_device);
  47
  48 int 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  */
  61 int 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  */
  69 int 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  */
  77 int 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  */
  84 int 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  */
  94 int dm_pool_abort_metadata(struct dm_pool_metadata *pmd);
  95
  96 /*
  97  * Set/get userspace transaction id.
  98  */
  99 int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
 100                                         uint64_t current_id,
 101                                         uint64_t new_id);
 102
 103 int 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  */
 115 int dm_pool_reserve_metadata_snap(struct dm_pool_metadata *pmd);
 116 int dm_pool_release_metadata_snap(struct dm_pool_metadata *pmd);
 117
 118 int 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  */
 128 int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
 129                              struct dm_thin_device **td);
 130
 131 int dm_pool_close_thin_device(struct dm_thin_device *td);
 132
 133 dm_thin_id dm_thin_dev_id(struct dm_thin_device *td);
 134
 135 struct 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  */
 146 int 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  * Obtain an unused block.
 151  */
 152 int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result);
 153
 154 /*
 155  * Insert or remove block.
 156  */
 157 int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
 158                          dm_block_t data_block);
 159
 160 int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block);
 161
 162 /*
 163  * Queries.
 164  */
 165 bool dm_thin_changed_this_transaction(struct dm_thin_device *td);
 166
 167 bool dm_pool_changed_this_transaction(struct dm_pool_metadata *pmd);
 168
 169 bool dm_thin_aborted_changes(struct dm_thin_device *td);
 170
 171 int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
 172                                      dm_block_t *highest_mapped);
 173
 174 int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result);
 175
 176 int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd,
 177                                  dm_block_t *result);
 178
 179 int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
 180                                           dm_block_t *result);
 181
 182 int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
 183                                   dm_block_t *result);
 184
 185 int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result);
 186
 187 int dm_pool_block_is_used(struct dm_pool_metadata *pmd, dm_block_t b, bool *result);
 188
 189 /*
 190  * Returns -ENOSPC if the new size is too small and already allocated
 191  * blocks would be lost.
 192  */
 193 int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
 194 int dm_pool_resize_metadata_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
 195
 196 /*
 197  * Flicks the underlying block manager into read only mode, so you know
 198  * that nothing is changing.
 199  */
 200 void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd);
 201 void dm_pool_metadata_read_write(struct dm_pool_metadata *pmd);
 202
 203 int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
 204                                         dm_block_t threshold,
 205                                         dm_sm_threshold_fn fn,
 206                                         void *context);
 207
 208 /*
 209  * Updates the superblock immediately.
 210  */
 211 int dm_pool_metadata_set_needs_check(struct dm_pool_metadata *pmd);
 212 bool dm_pool_metadata_needs_check(struct dm_pool_metadata *pmd);
 213
 214 /*
 215  * Issue any prefetches that may be useful.
 216  */
 217 void dm_pool_issue_prefetches(struct dm_pool_metadata *pmd);
 218
 219 /*----------------------------------------------------------------*/
 220
 221 #endif