root/drivers/md/dm-thin-metadata.h

INCLUDED FROM

   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  * Retrieve the next run of contiguously mapped blocks.  Useful for working
 151  * out where to break up IO.  Returns 0 on success, < 0 on error.
 152  */
 153 int dm_thin_find_mapped_range(struct dm_thin_device *td,
 154                               dm_block_t begin, dm_block_t end,
 155                               dm_block_t *thin_begin, dm_block_t *thin_end,
 156                               dm_block_t *pool_begin, bool *maybe_shared);
 157 
 158 /*
 159  * Obtain an unused block.
 160  */
 161 int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result);
 162 
 163 /*
 164  * Insert or remove block.
 165  */
 166 int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
 167                          dm_block_t data_block);
 168 
 169 int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block);
 170 int dm_thin_remove_range(struct dm_thin_device *td,
 171                          dm_block_t begin, dm_block_t end);
 172 
 173 /*
 174  * Queries.
 175  */
 176 bool dm_thin_changed_this_transaction(struct dm_thin_device *td);
 177 
 178 bool dm_pool_changed_this_transaction(struct dm_pool_metadata *pmd);
 179 
 180 bool dm_thin_aborted_changes(struct dm_thin_device *td);
 181 
 182 int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
 183                                      dm_block_t *highest_mapped);
 184 
 185 int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result);
 186 
 187 int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd,
 188                                  dm_block_t *result);
 189 
 190 int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
 191                                           dm_block_t *result);
 192 
 193 int dm_pool_get_metadata_dev_size(struct dm_pool_metadata *pmd,
 194                                   dm_block_t *result);
 195 
 196 int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result);
 197 
 198 int dm_pool_block_is_shared(struct dm_pool_metadata *pmd, dm_block_t b, bool *result);
 199 
 200 int dm_pool_inc_data_range(struct dm_pool_metadata *pmd, dm_block_t b, dm_block_t e);
 201 int dm_pool_dec_data_range(struct dm_pool_metadata *pmd, dm_block_t b, dm_block_t e);
 202 
 203 /*
 204  * Returns -ENOSPC if the new size is too small and already allocated
 205  * blocks would be lost.
 206  */
 207 int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
 208 int dm_pool_resize_metadata_dev(struct dm_pool_metadata *pmd, dm_block_t new_size);
 209 
 210 /*
 211  * Flicks the underlying block manager into read only mode, so you know
 212  * that nothing is changing.
 213  */
 214 void dm_pool_metadata_read_only(struct dm_pool_metadata *pmd);
 215 void dm_pool_metadata_read_write(struct dm_pool_metadata *pmd);
 216 
 217 int dm_pool_register_metadata_threshold(struct dm_pool_metadata *pmd,
 218                                         dm_block_t threshold,
 219                                         dm_sm_threshold_fn fn,
 220                                         void *context);
 221 
 222 /*
 223  * Updates the superblock immediately.
 224  */
 225 int dm_pool_metadata_set_needs_check(struct dm_pool_metadata *pmd);
 226 bool dm_pool_metadata_needs_check(struct dm_pool_metadata *pmd);
 227 
 228 /*
 229  * Issue any prefetches that may be useful.
 230  */
 231 void dm_pool_issue_prefetches(struct dm_pool_metadata *pmd);
 232 
 233 /* Pre-commit callback */
 234 typedef int (*dm_pool_pre_commit_fn)(void *context);
 235 
 236 void dm_pool_register_pre_commit_callback(struct dm_pool_metadata *pmd,
 237                                           dm_pool_pre_commit_fn fn,
 238                                           void *context);
 239 
 240 /*----------------------------------------------------------------*/
 241 
 242 #endif