drivers/md/dm-clone-metadata.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2019 Arrikto, Inc. All Rights Reserved.
   4  */
   5
   6 #ifndef DM_CLONE_METADATA_H
   7 #define DM_CLONE_METADATA_H
   8
   9 #include "persistent-data/dm-block-manager.h"
  10 #include "persistent-data/dm-space-map-metadata.h"
  11
  12 #define DM_CLONE_METADATA_BLOCK_SIZE DM_SM_METADATA_BLOCK_SIZE
  13
  14 /*
  15  * The metadata device is currently limited in size.
  16  */
  17 #define DM_CLONE_METADATA_MAX_SECTORS DM_SM_METADATA_MAX_SECTORS
  18
  19 /*
  20  * A metadata device larger than 16GB triggers a warning.
  21  */
  22 #define DM_CLONE_METADATA_MAX_SECTORS_WARNING (16 * (1024 * 1024 * 1024 >> SECTOR_SHIFT))
  23
  24 #define SPACE_MAP_ROOT_SIZE 128
  25
  26 /* dm-clone metadata */
  27 struct dm_clone_metadata;
  28
  29 /*
  30  * Set region status to hydrated.
  31  *
  32  * @cmd: The dm-clone metadata
  33  * @region_nr: The region number
  34  *
  35  * This function doesn't block, so it's safe to call it from interrupt context.
  36  */
  37 int dm_clone_set_region_hydrated(struct dm_clone_metadata *cmd, unsigned long region_nr);
  38
  39 /*
  40  * Set status of all regions in the provided range to hydrated, if not already
  41  * hydrated.
  42  *
  43  * @cmd: The dm-clone metadata
  44  * @start: Starting region number
  45  * @nr_regions: Number of regions in the range
  46  *
  47  * This function doesn't block, but since it uses spin_lock_irq()/spin_unlock_irq()
  48  * it's NOT safe to call it from any context where interrupts are disabled, e.g.,
  49  * from interrupt context.
  50  */
  51 int dm_clone_cond_set_range(struct dm_clone_metadata *cmd, unsigned long start,
  52                             unsigned long nr_regions);
  53
  54 /*
  55  * Read existing or create fresh metadata.
  56  *
  57  * @bdev: The device storing the metadata
  58  * @target_size: The target size
  59  * @region_size: The region size
  60  *
  61  * @returns: The dm-clone metadata
  62  *
  63  * This function reads the superblock of @bdev and checks if it's all zeroes.
  64  * If it is, it formats @bdev and creates fresh metadata. If it isn't, it
  65  * validates the metadata stored in @bdev.
  66  */
  67 struct dm_clone_metadata *dm_clone_metadata_open(struct block_device *bdev,
  68                                                  sector_t target_size,
  69                                                  sector_t region_size);
  70
  71 /*
  72  * Free the resources related to metadata management.
  73  */
  74 void dm_clone_metadata_close(struct dm_clone_metadata *cmd);
  75
  76 /*
  77  * Commit dm-clone metadata to disk.
  78  *
  79  * We use a two phase commit:
  80  *
  81  * 1. dm_clone_metadata_pre_commit(): Prepare the current transaction for
  82  *    committing. After this is called, all subsequent metadata updates, done
  83  *    through either dm_clone_set_region_hydrated() or
  84  *    dm_clone_cond_set_range(), will be part of the **next** transaction.
  85  *
  86  * 2. dm_clone_metadata_commit(): Actually commit the current transaction to
  87  *    disk and start a new transaction.
  88  *
  89  * This allows dm-clone to flush the destination device after step (1) to
  90  * ensure that all freshly hydrated regions, for which we are updating the
  91  * metadata, are properly written to non-volatile storage and won't be lost in
  92  * case of a crash.
  93  */
  94 int dm_clone_metadata_pre_commit(struct dm_clone_metadata *cmd);
  95 int dm_clone_metadata_commit(struct dm_clone_metadata *cmd);
  96
  97 /*
  98  * Reload the in core copy of the on-disk bitmap.
  99  *
 100  * This should be used after aborting a metadata transaction and setting the
 101  * metadata to read-only, to invalidate the in-core cache and make it match the
 102  * on-disk metadata.
 103  *
 104  * WARNING: It must not be called concurrently with either
 105  * dm_clone_set_region_hydrated() or dm_clone_cond_set_range(), as it updates
 106  * the region bitmap without taking the relevant spinlock. We don't take the
 107  * spinlock because dm_clone_reload_in_core_bitset() does I/O, so it may block.
 108  *
 109  * But, it's safe to use it after calling dm_clone_metadata_set_read_only(),
 110  * because the latter sets the metadata to read-only mode. Both
 111  * dm_clone_set_region_hydrated() and dm_clone_cond_set_range() refuse to touch
 112  * the region bitmap, after calling dm_clone_metadata_set_read_only().
 113  */
 114 int dm_clone_reload_in_core_bitset(struct dm_clone_metadata *cmd);
 115
 116 /*
 117  * Check whether dm-clone's metadata changed this transaction.
 118  */
 119 bool dm_clone_changed_this_transaction(struct dm_clone_metadata *cmd);
 120
 121 /*
 122  * Abort current metadata transaction and rollback metadata to the last
 123  * committed transaction.
 124  */
 125 int dm_clone_metadata_abort(struct dm_clone_metadata *cmd);
 126
 127 /*
 128  * Switches metadata to a read only mode. Once read-only mode has been entered
 129  * the following functions will return -EPERM:
 130  *
 131  *   dm_clone_metadata_pre_commit()
 132  *   dm_clone_metadata_commit()
 133  *   dm_clone_set_region_hydrated()
 134  *   dm_clone_cond_set_range()
 135  *   dm_clone_metadata_abort()
 136  */
 137 void dm_clone_metadata_set_read_only(struct dm_clone_metadata *cmd);
 138 void dm_clone_metadata_set_read_write(struct dm_clone_metadata *cmd);
 139
 140 /*
 141  * Returns true if the hydration of the destination device is finished.
 142  */
 143 bool dm_clone_is_hydration_done(struct dm_clone_metadata *cmd);
 144
 145 /*
 146  * Returns true if region @region_nr is hydrated.
 147  */
 148 bool dm_clone_is_region_hydrated(struct dm_clone_metadata *cmd, unsigned long region_nr);
 149
 150 /*
 151  * Returns true if all the regions in the range are hydrated.
 152  */
 153 bool dm_clone_is_range_hydrated(struct dm_clone_metadata *cmd,
 154                                 unsigned long start, unsigned long nr_regions);
 155
 156 /*
 157  * Returns the number of hydrated regions.
 158  */
 159 unsigned int dm_clone_nr_of_hydrated_regions(struct dm_clone_metadata *cmd);
 160
 161 /*
 162  * Returns the first unhydrated region with region_nr >= @start
 163  */
 164 unsigned long dm_clone_find_next_unhydrated_region(struct dm_clone_metadata *cmd,
 165                                                    unsigned long start);
 166
 167 /*
 168  * Get the number of free metadata blocks.
 169  */
 170 int dm_clone_get_free_metadata_block_count(struct dm_clone_metadata *cmd, dm_block_t *result);
 171
 172 /*
 173  * Get the total number of metadata blocks.
 174  */
 175 int dm_clone_get_metadata_dev_size(struct dm_clone_metadata *cmd, dm_block_t *result);
 176
 177 #endif /* DM_CLONE_METADATA_H */