1 files changed, 92 insertions, 0 deletions
diff --git a/include/fs/fs.h b/include/fs/fs.h
new file mode 100644
index 0000000..6e4ec4b
--- /dev/null
+++ b/include/fs/fs.h
@@ -0,0 +1,92 @@
+#pragma once
+#include "common/types.h"
+#include "kernel/spinlock.h"
+#include "fs/stat.h"
+
+class FileSystem;
+
+// VFS Inode (Abstract Base Class)
+
+class Inode
+{
+private:
+    ;
+public:
+    // VFS Common Fields
+    uint32 dev;  // Device number (VirtIO Block ID)
+    uint32 inum; // Inode number
+    int ref_cnt; // Memory reference count (number of struct file or processes referencing it)
+    int valid;   // Whether the data is valid (whether metadata has been read from disk)
+
+    Mutex lock; // Sleep lock: protects internal Inode data and atomicity of read/write operations
+
+    // Metadata Cache (for speeding up getattr)
+    short type;  // T_DIR, T_FILE, T_DEVICE
+    short major; // Major device number (only for T_DEVICE)
+    short minor; // Minor device number (only for T_DEVICE)
+    short nlink; // Number of hard links
+    uint32 size; // File size
+
+    Inode() : ref_cnt(0), valid(0)
+    {
+        lock.init("inode");
+    }
+    virtual ~Inode() {}
+
+    /* Core Operation Interface (Subclass Must Implement) */
+    // Update metadata
+    // Sync size, type, links, etc. from memory back to disk
+    virtual void update() = 0;
+    // Read content
+    // Read n bytes from the file at offset into dst
+    // Returns the actual number of bytes read, returns -1 on error
+    virtual int read(char *dst, uint32 off, uint32 n, int isUser) = 0;
+    // 3. Write content
+    // Write n bytes from src to the file at the given offset
+    // Need to handle file growth
+    virtual int write(const char *src, uint32 off, uint32 n, int isUser) = 0;
+    // Directory Lookup (only valid when type == T_DIR)
+    // Search for a file named 'name' in the current directory and return its Inode pointer (locked)
+    // Return nullptr if not found
+    virtual Inode *lookup(const char *name) = 0;
+    // Create file/directory (only effective when type == T_DIR)
+    // Create a new entry in the current directory
+    virtual Inode *create(const char *name, short type, short major, short minor) = 0;
+    // Get file status (populate the stat structure)
+    // Default implementation, subclasses can override to provide more detailed information
+    virtual void getattr(struct kstat *st);
+    // Truncate file (set size to 0, release all data blocks)
+    virtual void truncate() = 0;
+};
+
+// File System Abstraction (SuperBlock)
+class FileSystem
+{
+private:
+    ;
+public:
+    virtual void init() = 0;
+    virtual Inode* root() = 0;
+    virtual ~FileSystem() {};
+};
+
+// Inode Cache Interface (Global Function)
+namespace VFS
+{
+    void init();
+
+    // Decrease the reference count, and if it reaches 0, free the memory
+    void iput(Inode *ip);
+    // Increase reference count
+    Inode *idup(Inode *ip);
+    // lock and load data
+    void ilock(Inode *ip);
+    // unlock
+    void iunlock(Inode *ip);
+    // Mount the root filesystem
+    void mount_root(Inode *root);
+    // Get system root node
+    Inode *get_root();
+    // Path Analysis
+    Inode *namei(const char *path);
+} // namespace VFS