ref: 53b4f91981f5898473830d53c24c27e17f83a8a1
dir: /include/ext4_bcache.h/
/*
* Copyright (c) 2013 Grzegorz Kostka (kostka.grzegorz@gmail.com)
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup lwext4
* @{
*/
/**
* @file ext4_bcache.h
* @brief Block cache allocator.
*/
#ifndef EXT4_BCACHE_H_
#define EXT4_BCACHE_H_
#ifdef __cplusplus
extern "C" {
#endif
#include "ext4_config.h"
#include <stdint.h>
#include <stdbool.h>
#include "misc/tree.h"
#include "misc/queue.h"
#define EXT4_BLOCK_ZERO() \
{.lb_id = 0, .data = 0}
/**@brief Single block descriptor*/
struct ext4_block {
/**@brief Logical block ID*/
uint64_t lb_id;
/**@brief Buffer */
struct ext4_buf *buf;
/**@brief Data buffer.*/
uint8_t *data;
};
struct ext4_bcache;
/**@brief Single block descriptor*/
struct ext4_buf {
/**@brief Flags*/
int flags;
/**@brief Logical block address*/
uint64_t lba;
/**@brief Data buffer.*/
uint8_t *data;
/**@brief LRU priority. (unused) */
uint32_t lru_prio;
/**@brief LRU id.*/
uint32_t lru_id;
/**@brief Reference count table*/
uint32_t refctr;
/**@brief The block cache this buffer belongs to. */
struct ext4_bcache *bc;
/**@brief Whether or not buffer is on dirty list.*/
bool on_dirty_list;
/**@brief LBA tree node*/
RB_ENTRY(ext4_buf) lba_node;
/**@brief LRU tree node*/
RB_ENTRY(ext4_buf) lru_node;
/**@brief Dirty list node*/
SLIST_ENTRY(ext4_buf) dirty_node;
/**@brief Callback routine after a disk-write operation.
* @param bc block cache descriptor
* @param buf buffer descriptor
* @param standard error code returned by bdev->bwrite()
* @param arg argument passed to this routine*/
void (*end_write)(struct ext4_bcache *bc,
struct ext4_buf *buf,
int res,
void *arg);
/**@brief argument passed to end_write() callback.*/
void *end_write_arg;
};
/**@brief Block cache descriptor*/
struct ext4_bcache {
/**@brief Item count in block cache*/
uint32_t cnt;
/**@brief Item size in block cache*/
uint32_t itemsize;
/**@brief Last recently used counter*/
uint32_t lru_ctr;
/**@brief Currently referenced datablocks*/
uint32_t ref_blocks;
/**@brief Maximum referenced datablocks*/
uint32_t max_ref_blocks;
/**@brief The blockdev binded to this block cache*/
struct ext4_blockdev *bdev;
/**@brief The cache should not be shaked */
bool dont_shake;
/**@brief A tree holding all bufs*/
RB_HEAD(ext4_buf_lba, ext4_buf) lba_root;
/**@brief A tree holding unreferenced bufs*/
RB_HEAD(ext4_buf_lru, ext4_buf) lru_root;
/**@brief A singly-linked list holding dirty buffers*/
SLIST_HEAD(ext4_buf_dirty, ext4_buf) dirty_list;
};
/**@brief buffer state bits
*
* - BC♡UPTODATE: Buffer contains valid data.
* - BC_DIRTY: Buffer is dirty.
* - BC_FLUSH: Buffer will be immediately flushed,
* when no one references it.
* - BC_TMP: Buffer will be dropped once its refctr
* reaches zero.
*/
enum bcache_state_bits {
BC_UPTODATE,
BC_DIRTY,
BC_FLUSH,
BC_TMP
};
#define ext4_bcache_set_flag(buf, b) \
(buf)->flags |= 1 << (b)
#define ext4_bcache_clear_flag(buf, b) \
(buf)->flags &= ~(1 << (b))
#define ext4_bcache_test_flag(buf, b) \
(((buf)->flags & (1 << (b))) >> (b))
static inline void ext4_bcache_set_dirty(struct ext4_buf *buf) {
ext4_bcache_set_flag(buf, BC_UPTODATE);
ext4_bcache_set_flag(buf, BC_DIRTY);
}
static inline void ext4_bcache_clear_dirty(struct ext4_buf *buf) {
ext4_bcache_clear_flag(buf, BC_UPTODATE);
ext4_bcache_clear_flag(buf, BC_DIRTY);
}
/**@brief Increment reference counter of buf by 1.*/
#define ext4_bcache_inc_ref(buf) ((buf)->refctr++)
/**@brief Decrement reference counter of buf by 1.*/
#define ext4_bcache_dec_ref(buf) ((buf)->refctr--)
/**@brief Insert buffer to dirty cache list
* @param bc block cache descriptor
* @param buf buffer descriptor */
static inline void
ext4_bcache_insert_dirty_node(struct ext4_bcache *bc, struct ext4_buf *buf) {
if (!buf->on_dirty_list) {
SLIST_INSERT_HEAD(&bc->dirty_list, buf, dirty_node);
buf->on_dirty_list = true;
}
}
/**@brief Remove buffer to dirty cache list
* @param bc block cache descriptor
* @param buf buffer descriptor */
static inline void
ext4_bcache_remove_dirty_node(struct ext4_bcache *bc, struct ext4_buf *buf) {
if (buf->on_dirty_list) {
SLIST_REMOVE(&bc->dirty_list, buf, ext4_buf, dirty_node);
buf->on_dirty_list = false;
}
}
/**@brief Dynamic initialization of block cache.
* @param bc block cache descriptor
* @param cnt items count in block cache
* @param itemsize single item size (in bytes)
* @return standard error code*/
int ext4_bcache_init_dynamic(struct ext4_bcache *bc, uint32_t cnt,
uint32_t itemsize);
/**@brief Do cleanup works on block cache.
* @param bc block cache descriptor.*/
void ext4_bcache_cleanup(struct ext4_bcache *bc);
/**@brief Dynamic de-initialization of block cache.
* @param bc block cache descriptor
* @return standard error code*/
int ext4_bcache_fini_dynamic(struct ext4_bcache *bc);
/**@brief Get a buffer with the lowest LRU counter in bcache.
* @param bc block cache descriptor
* @return buffer with the lowest LRU counter*/
struct ext4_buf *ext4_buf_lowest_lru(struct ext4_bcache *bc);
/**@brief Drop unreferenced buffer from bcache.
* @param bc block cache descriptor
* @param buf buffer*/
void ext4_bcache_drop_buf(struct ext4_bcache *bc, struct ext4_buf *buf);
/**@brief Invalidate a range of buffers.
* @param bc block cache descriptor
* @param from starting lba
* @param cnt block counts
* @param buf buffer*/
void ext4_bcache_invalidate_lba(struct ext4_bcache *bc,
uint64_t from,
uint32_t cnt);
/**@brief Find existing buffer from block cache memory.
* Unreferenced block allocation is based on LRU
* (Last Recently Used) algorithm.
* @param bc block cache descriptor
* @param b block to alloc
* @param lba logical block address
* @return block cache buffer */
struct ext4_buf *
ext4_bcache_find_get(struct ext4_bcache *bc, struct ext4_block *b,
uint64_t lba);
/**@brief Allocate block from block cache memory.
* Unreferenced block allocation is based on LRU
* (Last Recently Used) algorithm.
* @param bc block cache descriptor
* @param b block to alloc
* @param is_new block is new (needs to be read)
* @return standard error code*/
int ext4_bcache_alloc(struct ext4_bcache *bc, struct ext4_block *b,
bool *is_new);
/**@brief Free block from cache memory (decrement reference counter).
* @param bc block cache descriptor
* @param b block to free
* @return standard error code*/
int ext4_bcache_free(struct ext4_bcache *bc, struct ext4_block *b);
/**@brief Return a full status of block cache.
* @param bc block cache descriptor
* @return full status*/
bool ext4_bcache_is_full(struct ext4_bcache *bc);
#ifdef __cplusplus
}
#endif
#endif /* EXT4_BCACHE_H_ */
/**
* @}
*/