323 lines
7.7 KiB
C
323 lines
7.7 KiB
C
/*
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* Copyright (c) 2007 Travis Geiselbrecht
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*
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* Use of this source code is governed by a MIT-style
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* license that can be found in the LICENSE file or at
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* https://opensource.org/licenses/MIT
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*/
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#include <lk/list.h>
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#include <stdlib.h>
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#include <assert.h>
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#include <string.h>
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#include <sys/types.h>
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#include <lk/debug.h>
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#include <lk/trace.h>
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#include <lib/bcache.h>
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#include <lib/bio.h>
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#define LOCAL_TRACE 0
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struct bcache_block {
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struct list_node node;
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bnum_t blocknum;
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int ref_count;
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bool is_dirty;
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void *ptr;
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};
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struct bcache_stats {
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uint32_t hits;
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uint32_t depth;
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uint32_t misses;
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uint32_t reads;
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uint32_t writes;
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};
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struct bcache {
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bdev_t *dev;
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size_t block_size;
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int count;
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struct bcache_stats stats;
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struct list_node free_list;
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struct list_node lru_list;
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struct bcache_block *blocks;
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};
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bcache_t bcache_create(bdev_t *dev, size_t block_size, int block_count) {
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struct bcache *cache;
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cache = malloc(sizeof(struct bcache));
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cache->dev = dev;
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cache->block_size = block_size;
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cache->count = block_count;
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memset(&cache->stats, 0, sizeof(cache->stats));
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list_initialize(&cache->free_list);
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list_initialize(&cache->lru_list);
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cache->blocks = malloc(sizeof(struct bcache_block) * block_count);
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int i;
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for (i=0; i < block_count; i++) {
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cache->blocks[i].ref_count = 0;
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cache->blocks[i].is_dirty = false;
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cache->blocks[i].ptr = malloc(block_size);
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// add to the free list
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list_add_head(&cache->free_list, &cache->blocks[i].node);
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}
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return (bcache_t)cache;
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}
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static int flush_block(struct bcache *cache, struct bcache_block *block) {
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int rc;
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rc = bio_write(cache->dev, block->ptr,
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(off_t)block->blocknum * cache->block_size,
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cache->block_size);
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if (rc < 0)
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goto exit;
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block->is_dirty = false;
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cache->stats.writes++;
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rc = 0;
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exit:
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return (rc);
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}
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void bcache_destroy(bcache_t _cache) {
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struct bcache *cache = _cache;
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int i;
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for (i=0; i < cache->count; i++) {
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DEBUG_ASSERT(cache->blocks[i].ref_count == 0);
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if (cache->blocks[i].is_dirty)
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printf("warning: freeing dirty block %u\n",
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cache->blocks[i].blocknum);
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free(cache->blocks[i].ptr);
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}
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free(cache);
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}
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/* find a block if it's already present */
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static struct bcache_block *find_block(struct bcache *cache, uint blocknum) {
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uint32_t depth = 0;
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struct bcache_block *block;
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LTRACEF("num %u\n", blocknum);
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block = NULL;
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list_for_every_entry(&cache->lru_list, block, struct bcache_block, node) {
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LTRACEF("looking at entry %p, num %u\n", block, block->blocknum);
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depth++;
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if (block->blocknum == blocknum) {
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list_delete(&block->node);
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list_add_tail(&cache->lru_list, &block->node);
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cache->stats.hits++;
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cache->stats.depth += depth;
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return block;
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}
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}
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cache->stats.misses++;
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return NULL;
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}
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/* allocate a new block */
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static struct bcache_block *alloc_block(struct bcache *cache) {
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int err;
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struct bcache_block *block;
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/* pop one off the free list if it's present */
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block = list_remove_head_type(&cache->free_list, struct bcache_block, node);
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if (block) {
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block->ref_count = 0;
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list_add_tail(&cache->lru_list, &block->node);
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LTRACEF("found block %p on free list\n", block);
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return block;
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}
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/* walk the lru, looking for a free block */
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list_for_every_entry(&cache->lru_list, block, struct bcache_block, node) {
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LTRACEF("looking at %p, num %u\n", block, block->blocknum);
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if (block->ref_count == 0) {
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if (block->is_dirty) {
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err = flush_block(cache, block);
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if (err)
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return NULL;
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}
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// add it to the tail of the lru
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list_delete(&block->node);
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list_add_tail(&cache->lru_list, &block->node);
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return block;
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}
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}
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return NULL;
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}
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static struct bcache_block *find_or_fill_block(struct bcache *cache, uint blocknum) {
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int err;
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LTRACEF("block %u\n", blocknum);
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/* see if it's already in the cache */
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struct bcache_block *block = find_block(cache, blocknum);
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if (block == NULL) {
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LTRACEF("wasn't allocated\n");
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/* allocate a new block and fill it */
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block = alloc_block(cache);
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DEBUG_ASSERT(block);
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LTRACEF("wasn't allocated, new block %p\n", block);
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block->blocknum = blocknum;
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err = bio_read(cache->dev, block->ptr, (off_t)blocknum * cache->block_size, cache->block_size);
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if (err < 0) {
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/* free the block, return an error */
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list_add_tail(&cache->free_list, &block->node);
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return NULL;
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}
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cache->stats.reads++;
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}
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DEBUG_ASSERT(block->blocknum == blocknum);
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return block;
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}
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int bcache_read_block(bcache_t _cache, void *buf, uint blocknum) {
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struct bcache *cache = _cache;
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LTRACEF("buf %p, blocknum %u\n", buf, blocknum);
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struct bcache_block *block = find_or_fill_block(cache, blocknum);
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if (block == NULL) {
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/* error */
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return -1;
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}
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memcpy(buf, block->ptr, cache->block_size);
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return 0;
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}
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int bcache_get_block(bcache_t _cache, void **ptr, uint blocknum) {
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struct bcache *cache = _cache;
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LTRACEF("ptr %p, blocknum %u\n", ptr, blocknum);
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DEBUG_ASSERT(ptr);
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struct bcache_block *block = find_or_fill_block(cache, blocknum);
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if (block == NULL) {
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/* error */
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return -1;
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}
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/* increment the ref count to keep it from being freed */
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block->ref_count++;
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*ptr = block->ptr;
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return 0;
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}
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int bcache_put_block(bcache_t _cache, uint blocknum) {
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struct bcache *cache = _cache;
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LTRACEF("blocknum %u\n", blocknum);
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struct bcache_block *block = find_block(cache, blocknum);
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/* be pretty hard on the caller for now */
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DEBUG_ASSERT(block);
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DEBUG_ASSERT(block->ref_count > 0);
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block->ref_count--;
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return 0;
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}
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int bcache_mark_block_dirty(bcache_t priv, uint blocknum) {
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int err;
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struct bcache *cache = priv;
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struct bcache_block *block;
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block = find_block(cache, blocknum);
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if (!block) {
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err = -1;
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goto exit;
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}
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block->is_dirty = true;
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err = 0;
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exit:
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return (err);
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}
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int bcache_zero_block(bcache_t priv, uint blocknum) {
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int err;
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struct bcache *cache = priv;
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struct bcache_block *block;
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block = find_block(cache, blocknum);
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if (!block) {
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block = alloc_block(cache);
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if (!block) {
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err = -1;
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goto exit;
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}
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block->blocknum = blocknum;
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}
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memset(block->ptr, 0, cache->block_size);
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block->is_dirty = true;
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err = 0;
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exit:
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return (err);
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}
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int bcache_flush(bcache_t priv) {
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int err;
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struct bcache *cache = priv;
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struct bcache_block *block;
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list_for_every_entry(&cache->lru_list, block, struct bcache_block, node) {
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if (block->is_dirty) {
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err = flush_block(cache, block);
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if (err)
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goto exit;
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}
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}
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err = 0;
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exit:
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return (err);
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}
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void bcache_dump(bcache_t priv, const char *name) {
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uint32_t finds;
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struct bcache *cache = priv;
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finds = cache->stats.hits + cache->stats.misses;
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printf("%s: hits=%u(%u%%) depth=%u misses=%u(%u%%) reads=%u writes=%u\n",
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name,
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cache->stats.hits,
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finds ? (cache->stats.hits * 100) / finds : 0,
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cache->stats.hits ? cache->stats.depth / cache->stats.hits : 0,
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cache->stats.misses,
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finds ? (cache->stats.misses * 100) / finds : 0,
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cache->stats.reads,
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cache->stats.writes);
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}
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