bcache.c

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#include <core/system.h>
#include <fs/bcache.h>
 
MALLOC_DEFINE(M_BCACHE, "bcache", "block cache structure");
MALLOC_DEFINE(M_CACHE_BLOCK, "cache block", "cached block structure");

struct cache_block {
    off_t off;      /* its number */
    void *data;     /* its contents */
 
    int dirty;      /* changed since it was read (not written back yet) */
};

static int bcache_eq(void *_a, void *_b)
{
    struct cache_block *a = (struct cache_block *) _a;
    off_t *b = (off_t *) _b;
 
    return a->off == *b;
}

void bcache_init(struct bcache *bcache)
{
    bcache->hashmap = hashmap_new(0, bcache_eq);
}

int bcache_insert(struct bcache *bcache, uint64_t off, void *data)
{
    if (!bcache)
        return -EINVAL;
 
    if (!bcache->hashmap)
        bcache_init(bcache);
 
    struct cache_block *block = kmalloc(sizeof(struct cache_block), &M_CACHE_BLOCK, M_ZERO);
    if (!block) return -ENOMEM;
 
    block->off = off;
    block->data = data;
 
    hash_t hash = hashmap_digest(&off, sizeof(off));
    return hashmap_insert(bcache->hashmap, hash, block);
}

int bcache_remove(struct bcache *bcache, uint64_t off)
{
    if (!bcache || !bcache->hashmap)
        return -1;
 
    hash_t hash = hashmap_digest(&off, sizeof(off));
 
    struct hashmap_node *node = hashmap_lookup(bcache->hashmap, hash, &off);
 
    if (node) {
        void *block = node->entry;
        node->entry = NULL;
        kfree(block);
        hashmap_node_remove(bcache->hashmap, node);
        return 0;
    }
 
    return -1;
}

void *bcache_find(struct bcache *bcache, uint64_t off)
{
    if (!bcache || !bcache->hashmap)
        return NULL;
 
    hash_t hash = hashmap_digest(&off, sizeof(off));
 
    struct hashmap_node *node = hashmap_lookup(bcache->hashmap, hash, &off);
 
    if (node) {
        struct cache_block *block = (struct cache_block *) node->entry;
        return block->data;
    }
 
    return NULL;
}

void bcache_dirty(struct bcache *bcache, uint64_t off)
{
    if (!bcache || !bcache->hashmap)
        return;
 
    hash_t hash = hashmap_digest(&off, sizeof(off));
 
    struct hashmap_node *node = hashmap_lookup(bcache->hashmap, hash, &off);
 
    if (node) {
        struct cache_block *block = (struct cache_block *) node->entry;
        block->dirty = 1;
    }
}