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 _LINUX_DM_BLOCK_MANAGER_H 9#define _LINUX_DM_BLOCK_MANAGER_H 10 11#include <linux/types.h> 12#include <linux/blkdev.h> 13 14/*----------------------------------------------------------------*/ 15 16/* 17 * Block number. 18 */ 19typedef uint64_t dm_block_t; 20struct dm_block; 21 22dm_block_t dm_block_location(struct dm_block *b); 23void *dm_block_data(struct dm_block *b); 24 25/*----------------------------------------------------------------*/ 26 27/* 28 * @name should be a unique identifier for the block manager, no longer 29 * than 32 chars. 30 * 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. 33 */ 34struct dm_block_manager; 35struct dm_block_manager *dm_block_manager_create( 36 struct block_device *bdev, unsigned int block_size, 37 unsigned int max_held_per_thread); 38void dm_block_manager_destroy(struct dm_block_manager *bm); 39void dm_block_manager_reset(struct dm_block_manager *bm); 40 41unsigned int dm_bm_block_size(struct dm_block_manager *bm); 42dm_block_t dm_bm_nr_blocks(struct dm_block_manager *bm); 43 44/*----------------------------------------------------------------*/ 45 46/* 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. 51 */ 52struct dm_block_validator { 53 const char *name; 54 void (*prepare_for_write)(struct dm_block_validator *v, struct dm_block *b, size_t block_size); 55 56 /* 57 * Return 0 if the checksum is valid or < 0 on error. 58 */ 59 int (*check)(struct dm_block_validator *v, struct dm_block *b, size_t block_size); 60}; 61 62/*----------------------------------------------------------------*/ 63 64/* 65 * You can have multiple concurrent readers or a single writer holding a 66 * block lock. 67 */ 68 69/* 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. 74 */ 75int dm_bm_read_lock(struct dm_block_manager *bm, dm_block_t b, 76 struct dm_block_validator *v, 77 struct dm_block **result); 78 79int dm_bm_write_lock(struct dm_block_manager *bm, dm_block_t b, 80 struct dm_block_validator *v, 81 struct dm_block **result); 82 83/* 84 * The *_try_lock variants return -EWOULDBLOCK if the block isn't 85 * available immediately. 86 */ 87int 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); 90 91/* 92 * Use dm_bm_write_lock_zero() when you know you're going to 93 * overwrite the block completely. It saves a disk read. 94 */ 95int 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); 98 99void dm_bm_unlock(struct dm_block *b); 100 101/* 102 * It's a common idiom to have a superblock that should be committed last. 103 * 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. 107 * 108 * This method always blocks. 109 */ 110int dm_bm_flush(struct dm_block_manager *bm); 111 112/* 113 * Request data is prefetched into the cache. 114 */ 115void dm_bm_prefetch(struct dm_block_manager *bm, dm_block_t b); 116 117/* 118 * Switches the bm to a read only mode. Once read-only mode 119 * has been entered the following functions will return -EPERM. 120 * 121 * dm_bm_write_lock 122 * dm_bm_write_lock_zero 123 * dm_bm_flush_and_unlock 124 * 125 * Additionally you should not use dm_bm_unlock_move, however no error will 126 * be returned if you do. 127 */ 128bool dm_bm_is_read_only(struct dm_block_manager *bm); 129void dm_bm_set_read_only(struct dm_block_manager *bm); 130void dm_bm_set_read_write(struct dm_block_manager *bm); 131 132u32 dm_bm_checksum(const void *data, size_t len, u32 init_xor); 133 134/*----------------------------------------------------------------*/ 135 136#endif /* _LINUX_DM_BLOCK_MANAGER_H */ 137