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

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2011 Red Hat, Inc.
 *
 * This file is released under the GPL.
 */

#ifndef DM_SPACE_MAP_COMMON_H
#define DM_SPACE_MAP_COMMON_H

#include "dm-btree.h"

/*----------------------------------------------------------------*/

/*
 * Low level disk format
 *
 * Bitmap btree
 * ------------
 *
 * Each value stored in the btree is an index_entry.  This points to a
 * block that is used as a bitmap.  Within the bitmap hold 2 bits per
 * entry, which represent UNUSED = 0, REF_COUNT = 1, REF_COUNT = 2 and
 * REF_COUNT = many.
 *
 * Refcount btree
 * --------------
 *
 * Any entry that has a ref count higher than 2 gets entered in the ref
 * count tree.  The leaf values for this tree is the 32-bit ref count.
 */

struct disk_index_entry { … } __packed __aligned(…);


#define MAX_METADATA_BITMAPS …
struct disk_metadata_index { … } __packed __aligned(…);

struct ll_disk;

load_ie_fn;
save_ie_fn;
init_index_fn;
open_index_fn;
max_index_entries_fn;
commit_fn;

/*
 * A lot of time can be wasted reading and writing the same
 * index entry.  So we cache a few entries.
 */
#define IE_CACHE_SIZE …
#define IE_CACHE_MASK …

struct ie_cache { … };

struct ll_disk { … };

struct disk_sm_root { … } __packed __aligned(…);

#define ENTRIES_PER_BYTE …

struct disk_bitmap_header { … } __packed __aligned(…);

/*----------------------------------------------------------------*/

int sm_ll_extend(struct ll_disk *ll, dm_block_t extra_blocks);
int sm_ll_lookup_bitmap(struct ll_disk *ll, dm_block_t b, uint32_t *result);
int sm_ll_lookup(struct ll_disk *ll, dm_block_t b, uint32_t *result);
int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
			  dm_block_t end, dm_block_t *result);
int sm_ll_find_common_free_block(struct ll_disk *old_ll, struct ll_disk *new_ll,
				 dm_block_t begin, dm_block_t end, dm_block_t *result);

/*
 * The next three functions return (via nr_allocations) the net number of
 * allocations that were made.  This number may be negative if there were
 * more frees than allocs.
 */
int sm_ll_insert(struct ll_disk *ll, dm_block_t b, uint32_t ref_count, int32_t *nr_allocations);
int sm_ll_inc(struct ll_disk *ll, dm_block_t b, dm_block_t e, int32_t *nr_allocations);
int sm_ll_dec(struct ll_disk *ll, dm_block_t b, dm_block_t e, int32_t *nr_allocations);
int sm_ll_commit(struct ll_disk *ll);

int sm_ll_new_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm);
int sm_ll_open_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm,
			void *root_le, size_t len);

int sm_ll_new_disk(struct ll_disk *ll, struct dm_transaction_manager *tm);
int sm_ll_open_disk(struct ll_disk *ll, struct dm_transaction_manager *tm,
		    void *root_le, size_t len);

/*----------------------------------------------------------------*/

#endif	/* DM_SPACE_MAP_COMMON_H */