ref: 46513990026f467c02bc405fcf7607ecac410900
dir: /lwext4/ext4_bcache.c/
/*
* 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.c
* @brief Block cache allocator.
*/
#include "ext4_config.h"
#include "ext4_bcache.h"
#include "ext4_debug.h"
#include "ext4_errno.h"
#include <string.h>
#include <stdlib.h>
int ext4_bcache_init_dynamic(struct ext4_bcache *bc, uint32_t cnt,
uint32_t itemsize)
{
ext4_assert(bc && cnt && itemsize);
memset(bc, 0, sizeof(struct ext4_bcache));
bc->data = malloc(cnt * itemsize);
if (!bc->data)
goto error;
bc->cnt = cnt;
bc->itemsize = itemsize;
bc->ref_blocks = 0;
bc->max_ref_blocks = 0;
return EOK;
error:
if (bc->data)
free(bc->data);
memset(bc, 0, sizeof(struct ext4_bcache));
return ENOMEM;
}
int ext4_bcache_fini_dynamic(struct ext4_bcache *bc)
{
if (bc->data)
free(bc->data);
memset(bc, 0, sizeof(struct ext4_bcache));
return EOK;
}
int ext4_bcache_alloc(struct ext4_bcache *bc, struct ext4_block *b,
bool *is_new)
{
uint32_t i;
ext4_assert(bc && b && is_new);
/*Check if valid.*/
ext4_assert(b->lb_id);
if (!b->lb_id) {
ext4_assert(b->lb_id);
}
uint32_t cache_id = bc->cnt;
uint32_t alloc_id = 0;
*is_new = false;
/*Find in free blocks (Last Recently Used).*/
for (i = 0; i < bc->cnt; ++i) {
/*Check if block is already in cache*/
if (b->lb_id == bc->lba[i]) {
if (!bc->refctr[i] && !bc->free_delay[i])
bc->ref_blocks++;
/*Update reference counter*/
bc->refctr[i]++;
/*Update usage marker*/
bc->lru_id[i] = ++bc->lru_ctr;
/*Set valid cache data and id*/
b->data = bc->data + i * bc->itemsize;
b->cache_id = i;
/* If data in the caxhe is up-to-date */
b->uptodate = ext4_bcache_test_flag(bc, i, BC_UPTODATE);
return EOK;
}
/*Best fit calculations.*/
if (bc->refctr[i])
continue;
if (bc->free_delay[i])
continue;
/*Block is unreferenced, but it may exist block with
* lower usage marker*/
/*First find.*/
if (cache_id == bc->cnt) {
cache_id = i;
alloc_id = bc->lru_id[i];
continue;
}
/*Next find*/
if (alloc_id <= bc->lru_id[i])
continue;
/*This block has lower alloc id marker*/
cache_id = i;
alloc_id = bc->lru_id[i];
}
if (cache_id != bc->cnt) {
/*There was unreferenced block*/
bc->lba[cache_id] = b->lb_id;
bc->refctr[cache_id] = 1;
bc->lru_id[cache_id] = ++bc->lru_ctr;
/*Set valid cache data and id*/
b->data = bc->data + cache_id * bc->itemsize;
b->cache_id = cache_id;
/* Data in the cache is not up-to-date anymore. */
ext4_bcache_clear_flag(bc, cache_id, BC_UPTODATE);
b->uptodate = false;
/*Statistics*/
bc->ref_blocks++;
if (bc->ref_blocks > bc->max_ref_blocks)
bc->max_ref_blocks = bc->ref_blocks;
/*Block needs to be read.*/
*is_new = true;
return EOK;
}
ext4_dbg(DEBUG_BCACHE, DBG_ERROR
"unable to alloc block cache!\n");
return ENOMEM;
}
int ext4_bcache_free(struct ext4_bcache *bc, struct ext4_block *b,
uint8_t free_delay)
{
ext4_assert(bc && b);
/*Check if valid.*/
ext4_assert(b->lb_id);
/*Block should be in cache.*/
ext4_assert(b->cache_id < bc->cnt);
/*Check if someone don't try free unreferenced block cache.*/
ext4_assert(bc->refctr[b->cache_id]);
/*Just decrease reference counter*/
if (bc->refctr[b->cache_id])
bc->refctr[b->cache_id]--;
if (free_delay)
bc->free_delay[b->cache_id] = free_delay;
/*Update statistics*/
if (!bc->refctr[b->cache_id] && !bc->free_delay[b->cache_id])
bc->ref_blocks--;
b->lb_id = 0;
b->data = 0;
b->cache_id = 0;
b->uptodate = false;
return EOK;
}
bool ext4_bcache_is_full(struct ext4_bcache *bc)
{
return (bc->cnt == bc->ref_blocks);
}
/**
* @}
*/