139 lines · c
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_H9#define _LINUX_DM_BLOCK_MANAGER_H10 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 longer29 * than 32 chars.30 *31 * @max_held_per_thread should be the maximum number of locks, read or32 * 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 modify48 * the data just before writing, e.g. to calculate checksums. It's49 * important to be consistent with your use of validators. The only time50 * 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)(const struct dm_block_validator *v,55 struct dm_block *b, size_t block_size);56 57 /*58 * Return 0 if the checksum is valid or < 0 on error.59 */60 int (*check)(const struct dm_block_validator *v,61 struct dm_block *b, size_t block_size);62};63 64/*----------------------------------------------------------------*/65 66/*67 * You can have multiple concurrent readers or a single writer holding a68 * block lock.69 */70 71/*72 * dm_bm_lock() locks a block and returns through @result a pointer to73 * memory that holds a copy of that block. If you have write-locked the74 * block then any changes you make to memory pointed to by @result will be75 * written back to the disk sometime after dm_bm_unlock is called.76 */77int dm_bm_read_lock(struct dm_block_manager *bm, dm_block_t b,78 const struct dm_block_validator *v,79 struct dm_block **result);80 81int dm_bm_write_lock(struct dm_block_manager *bm, dm_block_t b,82 const struct dm_block_validator *v,83 struct dm_block **result);84 85/*86 * The *_try_lock variants return -EWOULDBLOCK if the block isn't87 * available immediately.88 */89int dm_bm_read_try_lock(struct dm_block_manager *bm, dm_block_t b,90 const struct dm_block_validator *v,91 struct dm_block **result);92 93/*94 * Use dm_bm_write_lock_zero() when you know you're going to95 * overwrite the block completely. It saves a disk read.96 */97int dm_bm_write_lock_zero(struct dm_block_manager *bm, dm_block_t b,98 const struct dm_block_validator *v,99 struct dm_block **result);100 101void dm_bm_unlock(struct dm_block *b);102 103/*104 * It's a common idiom to have a superblock that should be committed last.105 *106 * @superblock should be write-locked on entry. It will be unlocked during107 * this function. All dirty blocks are guaranteed to be written and flushed108 * before the superblock.109 *110 * This method always blocks.111 */112int dm_bm_flush(struct dm_block_manager *bm);113 114/*115 * Request data is prefetched into the cache.116 */117void dm_bm_prefetch(struct dm_block_manager *bm, dm_block_t b);118 119/*120 * Switches the bm to a read only mode. Once read-only mode121 * has been entered the following functions will return -EPERM.122 *123 * dm_bm_write_lock124 * dm_bm_write_lock_zero125 * dm_bm_flush_and_unlock126 *127 * Additionally you should not use dm_bm_unlock_move, however no error will128 * be returned if you do.129 */130bool dm_bm_is_read_only(struct dm_block_manager *bm);131void dm_bm_set_read_only(struct dm_block_manager *bm);132void dm_bm_set_read_write(struct dm_block_manager *bm);133 134u32 dm_bm_checksum(const void *data, size_t len, u32 init_xor);135 136/*----------------------------------------------------------------*/137 138#endif /* _LINUX_DM_BLOCK_MANAGER_H */139