From b1f7fd80939193423888e11bd3ee614dd0d4748e Mon Sep 17 00:00:00 2001
From: acevest <zhaoyanbai@126.com>
Date: Thu, 19 Oct 2023 21:23:19 +0800
Subject: [PATCH] ...

---
 fs/buffer.c      | 103 +++++++++++++++++++++++++++++++++++++++++++++--
 include/buffer.h |  13 +++---
 include/list.h   |   2 +
 kernel/setup.c   |   3 ++
 4 files changed, 112 insertions(+), 9 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index ecc4efd..3074b29 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -3,20 +3,115 @@
  *   File Name: buffer.c
  *      Author: Zhao Yanbai
  *              2023-06-20 19:30:33 Tuesday CST
- * Description: none
+ * Description: 目前只支持只读，因此可以先写得简单一点
  * ------------------------------------------------------------------------
  */
 
 #include <buffer.h>
 
+#define MAX_BBUFFER_CNT 985
+
 #define BLOCK_BUFFER_HASH_TABLE_SIZE 211
 // atomic_t hash_cnt;
-bbuffer_t *block_buffer_hash_table[BLOCK_BUFFER_HASH_TABLE_SIZE] = {
+list_head_t block_buffer_hash_table[BLOCK_BUFFER_HASH_TABLE_SIZE] = {
     0,
 };
 
-int hash(dev_t dev, uint32_t block) { return ((~dev) ^ block) % BLOCK_BUFFER_HASH_TABLE_SIZE; }
+typedef struct bbuffer_store {
+    int blocksize;
+    list_head_t cache_list;
+    list_head_t free_list;
+} bbuffer_store_t;
+
+// 1024, 2048, 4096
+bbuffer_store_t store[3] = {0};
+
+int hashfn(dev_t dev, uint32_t block) { return ((dev) ^ block) % BLOCK_BUFFER_HASH_TABLE_SIZE; }
 
 bbuffer_t *get_hash_block_buffer(dev_t dev, uint32_t block, uint16_t size) {}
 
-void init_buffer() {}
+kmem_cache_t *bbufer_kmem_cache = 0;
+
+bbuffer_t *bread(dev_t dev, uint64_t block, uint32_t size) {
+    assert(size == 1024 || size == 2048 || size == 4096);
+
+    // 暂时先只支持hard disk
+    assert(DEV_MAJOR(dev) == DEV_MAJOR_DISK);
+
+    // 先尝试从hash里分配
+    list_head_t *p = 0;
+    uint32_t hash = hashfn(dev, block);
+    list_for_each(p, block_buffer_hash_table + hash) {
+        bbuffer_t *b = list_entry(p, bbuffer_t, node);
+        if (b->dev != dev) {
+            continue;
+        }
+        if (b->block == block) {
+            continue;
+        }
+
+        break;
+    }
+
+    // 如果找到了就直接返回
+    if (0 != p) {
+        bbuffer_t *b = list_entry(p, bbuffer_t, node);
+        assert(0 != b);
+        assert(0 != b->data);
+        return b;
+    }
+
+    // 如果没找到，则从store的cached_list里尝试找
+
+    // 如果没找到，则尝试从store里的free_list里尝试分配
+
+    // 如果free_list为空，且cached_list不为空，
+}
+
+void init_buffer() {
+    for (int i = 0; i < BLOCK_BUFFER_HASH_TABLE_SIZE; i++) {
+        list_init(block_buffer_hash_table + i);
+    }
+
+    bbufer_kmem_cache = kmem_cache_create("bbuffer", sizeof(bbuffer_t), 4);
+    if (0 == bbufer_kmem_cache) {
+        panic("no memory for bbufer kmem cache");
+    }
+
+    printk("bbufer kmem cache %08x\n", bbufer_kmem_cache);
+
+    for (int i = 0; i < 3; i++) {
+        int blocksize = 1 << (10 + i);
+
+        store[i].blocksize = blocksize;
+        list_init(&store[i].cache_list);
+        list_init(&store[i].free_list);
+
+        int page_left_space = 0;
+        void *data = 0;
+        page_t *page = 0;
+        for (int j = 0; j < MAX_BBUFFER_CNT; j++) {
+            if (page_left_space < blocksize) {
+                data = (void *)(alloc_one_page(0));
+                page = va2page(data);
+            }
+
+            bbuffer_t *b = kmem_cache_alloc(bbufer_kmem_cache, 0);
+            assert(b != 0);
+
+            b->block = 0;
+            b->block_size = blocksize;
+            b->ref_count = 0;
+            b->data = data + j * blocksize;
+            b->dev = 0;
+            b->page = page;
+            list_init(&b->node);
+
+            assert(0 != b->data);
+
+            list_add(&b->node, &store[i].free_list);
+
+            page_left_space -= blocksize;
+        }
+    }
+}
diff --git a/include/buffer.h b/include/buffer.h
index 1299ba9..a15b5c1 100644
--- a/include/buffer.h
+++ b/include/buffer.h
@@ -10,13 +10,16 @@
 #pragma once
 
 #include <fs.h>
+#include <mm.h>
+#include <page.h>
+#include <system.h>
 
 typedef struct bbuffer {
-    uint32_t block;       // block number
-    char *data;           //
-    uint16_t block_size;  // block size
+    uint32_t block;  // block number
+    char *data;      //
+    uint32_t ref_count;
     dev_t dev;
     page_t *page;
-    struct bbuffer *next;
-    struct bbuffer *hash_next;
+    list_head_t node;
+    uint16_t block_size;  // block size
 } bbuffer_t;
diff --git a/include/list.h b/include/list.h
index 8ee3395..e995408 100644
--- a/include/list.h
+++ b/include/list.h
@@ -69,3 +69,5 @@ static inline void list_del_init(list_head_t *entry) {
 }
 
 static inline int list_empty(list_head_t *head) { return head->next == head; }
+
+static inline void list_init(list_head_t *head) { INIT_LIST_HEAD(head); }
diff --git a/kernel/setup.c b/kernel/setup.c
index d947589..12e2314 100644
--- a/kernel/setup.c
+++ b/kernel/setup.c
@@ -20,6 +20,7 @@
 #include <tty.h>
 
 extern void init_mm();
+extern void init_buffer();
 extern void setup_gdt();
 extern void setup_idt();
 extern void setup_gate();
@@ -55,6 +56,8 @@ void setup_kernel() {
 
     init_mm();
 
+    init_buffer();
+
     // printk("kernel: %08x - %08x\n", system.kernel_begin, system.kernel_end);
     boot_delay(DEFAULT_BOOT_DELAY_TICKS);
 
-- 
2.44.0