drivers/md/persistent-data/dm-space-map-common.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2011 Red Hat, Inc.
   4  *
   5  * This file is released under the GPL.
   6  */
   7
   8 #ifndef DM_SPACE_MAP_COMMON_H
   9 #define DM_SPACE_MAP_COMMON_H
  10
  11 #include "dm-btree.h"
  12
  13 /*----------------------------------------------------------------*/
  14
  15 /*
  16  * Low level disk format
  17  *
  18  * Bitmap btree
  19  * ------------
  20  *
  21  * Each value stored in the btree is an index_entry.  This points to a
  22  * block that is used as a bitmap.  Within the bitmap hold 2 bits per
  23  * entry, which represent UNUSED = 0, REF_COUNT = 1, REF_COUNT = 2 and
  24  * REF_COUNT = many.
  25  *
  26  * Refcount btree
  27  * --------------
  28  *
  29  * Any entry that has a ref count higher than 2 gets entered in the ref
  30  * count tree.  The leaf values for this tree is the 32-bit ref count.
  31  */
  32
  33 struct disk_index_entry {
  34         __le64 blocknr;
  35         __le32 nr_free;
  36         __le32 none_free_before;
  37 } __packed __aligned(8);
  38
  39
  40 #define MAX_METADATA_BITMAPS 255
  41 struct disk_metadata_index {
  42         __le32 csum;
  43         __le32 padding;
  44         __le64 blocknr;
  45
  46         struct disk_index_entry index[MAX_METADATA_BITMAPS];
  47 } __packed __aligned(8);
  48
  49 struct ll_disk;
  50
  51 typedef int (*load_ie_fn)(struct ll_disk *ll, dm_block_t index, struct disk_index_entry *result);
  52 typedef int (*save_ie_fn)(struct ll_disk *ll, dm_block_t index, struct disk_index_entry *ie);
  53 typedef int (*init_index_fn)(struct ll_disk *ll);
  54 typedef int (*open_index_fn)(struct ll_disk *ll);
  55 typedef dm_block_t (*max_index_entries_fn)(struct ll_disk *ll);
  56 typedef int (*commit_fn)(struct ll_disk *ll);
  57
  58 /*
  59  * A lot of time can be wasted reading and writing the same
  60  * index entry.  So we cache a few entries.
  61  */
  62 #define IE_CACHE_SIZE 64
  63 #define IE_CACHE_MASK (IE_CACHE_SIZE - 1)
  64
  65 struct ie_cache {
  66         bool valid;
  67         bool dirty;
  68         dm_block_t index;
  69         struct disk_index_entry ie;
  70 };
  71
  72 struct ll_disk {
  73         struct dm_transaction_manager *tm;
  74         struct dm_btree_info bitmap_info;
  75         struct dm_btree_info ref_count_info;
  76
  77         uint32_t block_size;
  78         uint32_t entries_per_block;
  79         dm_block_t nr_blocks;
  80         dm_block_t nr_allocated;
  81
  82         /*
  83          * bitmap_root may be a btree root or a simple index.
  84          */
  85         dm_block_t bitmap_root;
  86
  87         dm_block_t ref_count_root;
  88
  89         struct disk_metadata_index mi_le;
  90         load_ie_fn load_ie;
  91         save_ie_fn save_ie;
  92         init_index_fn init_index;
  93         open_index_fn open_index;
  94         max_index_entries_fn max_entries;
  95         commit_fn commit;
  96         bool bitmap_index_changed:1;
  97
  98         struct ie_cache ie_cache[IE_CACHE_SIZE];
  99 };
 100
 101 struct disk_sm_root {
 102         __le64 nr_blocks;
 103         __le64 nr_allocated;
 104         __le64 bitmap_root;
 105         __le64 ref_count_root;
 106 } __packed __aligned(8);
 107
 108 #define ENTRIES_PER_BYTE 4
 109
 110 struct disk_bitmap_header {
 111         __le32 csum;
 112         __le32 not_used;
 113         __le64 blocknr;
 114 } __packed __aligned(8);
 115
 116 /*----------------------------------------------------------------*/
 117
 118 int sm_ll_extend(struct ll_disk *ll, dm_block_t extra_blocks);
 119 int sm_ll_lookup_bitmap(struct ll_disk *ll, dm_block_t b, uint32_t *result);
 120 int sm_ll_lookup(struct ll_disk *ll, dm_block_t b, uint32_t *result);
 121 int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
 122                           dm_block_t end, dm_block_t *result);
 123 int sm_ll_find_common_free_block(struct ll_disk *old_ll, struct ll_disk *new_ll,
 124                                  dm_block_t begin, dm_block_t end, dm_block_t *result);
 125
 126 /*
 127  * The next three functions return (via nr_allocations) the net number of
 128  * allocations that were made.  This number may be negative if there were
 129  * more frees than allocs.
 130  */
 131 int sm_ll_insert(struct ll_disk *ll, dm_block_t b, uint32_t ref_count, int32_t *nr_allocations);
 132 int sm_ll_inc(struct ll_disk *ll, dm_block_t b, dm_block_t e, int32_t *nr_allocations);
 133 int sm_ll_dec(struct ll_disk *ll, dm_block_t b, dm_block_t e, int32_t *nr_allocations);
 134 int sm_ll_commit(struct ll_disk *ll);
 135
 136 int sm_ll_new_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm);
 137 int sm_ll_open_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm,
 138                         void *root_le, size_t len);
 139
 140 int sm_ll_new_disk(struct ll_disk *ll, struct dm_transaction_manager *tm);
 141 int sm_ll_open_disk(struct ll_disk *ll, struct dm_transaction_manager *tm,
 142                     void *root_le, size_t len);
 143
 144 /*----------------------------------------------------------------*/
 145
 146 #endif  /* DM_SPACE_MAP_COMMON_H */