1 /* SPDX-License-Identifier: GPL-2.0-only */
3 * Copyright (C) 2011 Red Hat, Inc.
5 * This file is released under the GPL.
8 #ifndef _LINUX_DM_BLOCK_MANAGER_H
9 #define _LINUX_DM_BLOCK_MANAGER_H
11 #include <linux/types.h>
12 #include <linux/blkdev.h>
14 /*----------------------------------------------------------------*/
19 typedef uint64_t dm_block_t;
22 dm_block_t dm_block_location(struct dm_block *b);
23 void *dm_block_data(struct dm_block *b);
25 /*----------------------------------------------------------------*/
28 * @name should be a unique identifier for the block manager, no longer
31 * @max_held_per_thread should be the maximum number of locks, read or
32 * write, that an individual thread holds at any one time.
34 struct dm_block_manager;
35 struct dm_block_manager *dm_block_manager_create(
36 struct block_device *bdev, unsigned int block_size,
37 unsigned int max_held_per_thread);
38 void dm_block_manager_destroy(struct dm_block_manager *bm);
39 void dm_block_manager_reset(struct dm_block_manager *bm);
41 unsigned int dm_bm_block_size(struct dm_block_manager *bm);
42 dm_block_t dm_bm_nr_blocks(struct dm_block_manager *bm);
44 /*----------------------------------------------------------------*/
47 * The validator allows the caller to verify newly-read data and modify
48 * the data just before writing, e.g. to calculate checksums. It's
49 * important to be consistent with your use of validators. The only time
50 * you can change validators is if you call dm_bm_write_lock_zero.
52 struct dm_block_validator {
54 void (*prepare_for_write)(struct dm_block_validator *v, struct dm_block *b, size_t block_size);
57 * Return 0 if the checksum is valid or < 0 on error.
59 int (*check)(struct dm_block_validator *v, struct dm_block *b, size_t block_size);
62 /*----------------------------------------------------------------*/
65 * You can have multiple concurrent readers or a single writer holding a
70 * dm_bm_lock() locks a block and returns through @result a pointer to
71 * memory that holds a copy of that block. If you have write-locked the
72 * block then any changes you make to memory pointed to by @result will be
73 * written back to the disk sometime after dm_bm_unlock is called.
75 int dm_bm_read_lock(struct dm_block_manager *bm, dm_block_t b,
76 struct dm_block_validator *v,
77 struct dm_block **result);
79 int dm_bm_write_lock(struct dm_block_manager *bm, dm_block_t b,
80 struct dm_block_validator *v,
81 struct dm_block **result);
84 * The *_try_lock variants return -EWOULDBLOCK if the block isn't
85 * available immediately.
87 int dm_bm_read_try_lock(struct dm_block_manager *bm, dm_block_t b,
88 struct dm_block_validator *v,
89 struct dm_block **result);
92 * Use dm_bm_write_lock_zero() when you know you're going to
93 * overwrite the block completely. It saves a disk read.
95 int dm_bm_write_lock_zero(struct dm_block_manager *bm, dm_block_t b,
96 struct dm_block_validator *v,
97 struct dm_block **result);
99 void dm_bm_unlock(struct dm_block *b);
102 * It's a common idiom to have a superblock that should be committed last.
104 * @superblock should be write-locked on entry. It will be unlocked during
105 * this function. All dirty blocks are guaranteed to be written and flushed
106 * before the superblock.
108 * This method always blocks.
110 int dm_bm_flush(struct dm_block_manager *bm);
113 * Request data is prefetched into the cache.
115 void dm_bm_prefetch(struct dm_block_manager *bm, dm_block_t b);
118 * Switches the bm to a read only mode. Once read-only mode
119 * has been entered the following functions will return -EPERM.
122 * dm_bm_write_lock_zero
123 * dm_bm_flush_and_unlock
125 * Additionally you should not use dm_bm_unlock_move, however no error will
126 * be returned if you do.
128 bool dm_bm_is_read_only(struct dm_block_manager *bm);
129 void dm_bm_set_read_only(struct dm_block_manager *bm);
130 void dm_bm_set_read_write(struct dm_block_manager *bm);
132 u32 dm_bm_checksum(const void *data, size_t len, u32 init_xor);
134 /*----------------------------------------------------------------*/
136 #endif /* _LINUX_DM_BLOCK_MANAGER_H */