cache.c

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// Copyright (c) 2025 Mohammad Arfan
 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
 
#include "autoconf.h"
#include "init/init.h"
#include "libk/serial.h"
#include "llist.h"
#include "type.h"
#include <hash.h>
#include <str.h>
#include <type.h>
#include <vfs/cache.h>
#include <vfs/dentry.h>
 
static struct vfs_cache* cache_ = 0;
 
INIT(VfsCache) {
    cache_ = create_vfs_cache();
    serial2_printf("cache at 0x%x\n", cache_);
}
 
struct vfs_cache* create_vfs_cache() {
    struct vfs_cache* cache =
        (struct vfs_cache*)kalloc(sizeof(struct vfs_cache));
    memset(cache, 0, sizeof(struct vfs_cache));
    cache->count = 0;
    __atomic_clear(&cache->lock, __ATOMIC_RELAXED);
    serial2_printf("create cache at 0x%x\n", cache);
    return cache;
}
 
void hlist_add_head(struct hlist_node* n, struct hlist_head* h) {
    struct hlist_node* first = h->first;
    n->next = first;
    n->prev = NULL;
    if (first)
        first->prev = n;
    h->first = n;
}
 
static void hlist_del(struct hlist_node* n, struct hlist_head* h) {
    if (n->prev) {
        n->prev->next = n->next;
    } else {
        h->first = n->next;
    }
 
    if (n->next) {
        n->next->prev = n->prev;
    }
 
    n->next = n->prev = NULL;
}
 
__attribute__((always_inline)) void vfs_cache_insert(struct vfs_cache* cache,
                                                     struct dentry* dentry) {
    while (__atomic_test_and_set(&cache->lock, __ATOMIC_ACQUIRE))
        ;
 
    auto idx = dentry->hash & (VFS_CACHE_SIZE - 1);
 
    hlist_add_head(&dentry->hash_node, &cache->buckets[idx]);
    __atomic_fetch_add(&cache->count, 1, __ATOMIC_RELAXED);
 
    bool has_parent = dentry->parent != NULL;
    if (has_parent)
        llist_add_tail(&dentry->siblings, &dentry->parent->child_list);
 
    __atomic_clear(&cache->lock, __ATOMIC_RELEASE); // release dulu
 
    if (!has_parent)
        LOG_DEBUG("VFS", "'%s' has no parent", dentry->name->c_str);
}
 
struct dentry* cache_lookup(struct vfs_cache* cache, struct dentry* parent,
                            const char* name) {
    uint32_t h = hash_dentry(name, parent);
    auto idx = h & (VFS_CACHE_SIZE - 1);
 
    while (__atomic_test_and_set(&cache->lock, __ATOMIC_ACQUIRE))
        ;
 
    struct hlist_head* bucket = &cache->buckets[idx];
 
    for (struct hlist_node* pos = bucket->first; pos != NULL;
         pos = pos->next) {
        struct dentry* d = container_of(pos, struct dentry, hash_node);
        if (d->parent == parent && strcmp(d->name->c_str, name) == 0) {
            __atomic_clear(&cache->lock, __ATOMIC_RELEASE);
            return d;
        }
    }
 
    __atomic_clear(&cache->lock, __ATOMIC_RELEASE);
 
    return 0;
}
 
void cache_remove(struct vfs_cache* cache, struct dentry* dentry) {
    while (__atomic_test_and_set(&cache->lock, __ATOMIC_ACQUIRE))
        ;
 
    uint32_t idx = dentry->hash & (VFS_CACHE_SIZE - 1);
    hlist_del(&dentry->hash_node, &cache->buckets[idx]);
    __atomic_fetch_sub(&cache->count, 1, __ATOMIC_RELAXED);
 
    __atomic_clear(&cache->lock, __ATOMIC_RELEASE);
}
 
KERNEL_API struct vfs_cache* get_root_cache() { return cache_; }