实现free指令+修复 mountfs的内存泄露问题(#394)

* 实现meminfo文件

* 成功实现free指令，添加了一些string有关函数，并进行一些无影响的小改动


* 解决内存泄露的问题：mountfs inode的wrap方法使用了Arc::into_raw而没有from_raw，导致inode始终无法释放

---------

Co-authored-by: LoGin <longjin@DragonOS.org>
Co-authored-by: longjin <longjin@RinGoTek.cn>

kernel/src/mm/allocator/buddy.rs

@@ -65,6 +65,8 @@ impl<A> PageList<A> {
 pub struct BuddyAllocator<A> {
     // 存放每个阶的空闲“链表”的头部地址
     free_area: [PhysAddr; (MAX_ORDER - MIN_ORDER) as usize],
+    /// 总页数
+    total: PageFrameCount,
     phantom: PhantomData<A>,
 }
 
@@ -227,9 +229,9 @@ impl<A: MemoryManagementArch> BuddyAllocator<A> {
         assert!(remain_bytes == 0);
         assert!(paddr == initial_bump_offset + pages_to_buddy.data() * A::PAGE_SIZE);
 
-        // Self::print_free_area(free_area);
         let allocator = Self {
             free_area,
+            total: pages_to_buddy,
             phantom: PhantomData,
         };
 
@@ -357,7 +359,6 @@ impl<A: MemoryManagementArch> BuddyAllocator<A> {
             }
             return None;
         };
-
         let result: Option<PhysAddr> = alloc_in_specific_order(order as u8);
         // kdebug!("result={:?}", result);
         if result.is_some() {
@@ -662,7 +663,19 @@ impl<A: MemoryManagementArch> FrameAllocator for BuddyAllocator<A> {
     }
 
     unsafe fn usage(&self) -> PageFrameUsage {
-        todo!("BuddyAllocator::usage")
+        let mut free_page_num: usize = 0;
+        for index in 0..(MAX_ORDER - MIN_ORDER) {
+            let mut pagelist: PageList<A> = Self::read_page(self.free_area[index]);
+            loop {
+                free_page_num += pagelist.entry_num << index;
+                if pagelist.next_page.is_null() {
+                    break;
+                }
+                pagelist = Self::read_page(pagelist.next_page);
+            }
+        }
+        let free = PageFrameCount::new(free_page_num);
+        PageFrameUsage::new(self.total - free, self.total)
     }
 }
 

kernel/src/mm/allocator/page_frame.rs

@@ -273,7 +273,7 @@ impl PageFrameUsage {
     }
     // @brief 获取空闲的页帧数量
     pub fn free(&self) -> PageFrameCount {
-        return PageFrameCount(self.total.0 - self.used.0);
+        return self.total - self.used;
     }
     // @brief 获取总的页帧数量
     pub fn total(&self) -> PageFrameCount {