new: rootfs

kernel/filesystem/rootfs/rootfs.c

@@ -1,6 +1,224 @@
 #include "rootfs.h"
 #include <filesystem/VFS/VFS.h>
+#include <common/string.h>
+#include <filesystem/VFS/mount.h>
+
+static struct vfs_superblock_t rootfs_sb = {0};
+extern struct vfs_superblock_t *vfs_root_sb;
+
+/**
+ * @brief 释放dentry本身所占的内存
+ *
+ * @param dentry
+ */
+static inline void __release_dentry(struct vfs_dir_entry_t *dentry)
+{
+    kfree(dentry->name);
+    kfree(dentry);
+}
+
+struct vfs_super_block_operations_t rootfs_sb_ops = {
+    .put_superblock = NULL,
+    .write_inode = NULL,
+    .write_superblock = NULL,
+};
+
+static struct vfs_dir_entry_t *rootfs_lookup(struct vfs_index_node_t *parent_inode, struct vfs_dir_entry_t *dest_dEntry)
+{
+    return NULL;
+}
+struct vfs_inode_operations_t rootfs_inode_ops = {
+    .create = NULL,
+    .getAttr = NULL,
+    .lookup = NULL,
+    .lookup = &rootfs_lookup,
+    .mkdir = NULL,
+    .rename = NULL,
+    .rmdir = NULL,
+    .setAttr = NULL,
+};
+
+static long rootfs_open(struct vfs_index_node_t *inode, struct vfs_file_t *file_ptr)
+{
+    return 0;
+}
+static long rootfs_close(struct vfs_index_node_t *inode, struct vfs_file_t *file_ptr) { return 0; }
+static long rootfs_read(struct vfs_file_t *file_ptr, char *buf, int64_t count, long *position) { return 0; }
+static long rootfs_write(struct vfs_file_t *file_ptr, char *buf, int64_t count, long *position) { return 0; }
+static long rootfs_lseek(struct vfs_file_t *file_ptr, long offset, long origin) { return 0; }
+static long rootfs_ioctl(struct vfs_index_node_t *inode, struct vfs_file_t *file_ptr, uint64_t cmd, uint64_t arg) { return 0; }
+
+static long rootfs_readdir(struct vfs_file_t *file_ptr, void *dirent, vfs_filldir_t filler)
+{
+    // 循环读取目录下的目录项
+    struct vfs_dir_entry_t *dentry = file_ptr->dEntry;
+    struct List *list = &dentry->subdirs_list;
+    // 先切换到position处
+    for (int i = 0; i <= file_ptr->position; ++i)
+    {
+        list = list_next(list);
+        if (list == &dentry->subdirs_list) // 找完了
+            goto failed;
+    }
+
+    // 存在目录项
+    // 增加偏移量
+    ++file_ptr->position;
+    // 获取目标dentry（由于是子目录项，因此是child_node_list）
+    struct vfs_dir_entry_t *target_dent = container_of(list, struct vfs_dir_entry_t, child_node_list);
+    // kdebug("target name=%s, namelen=%d", target_dent->name, target_dent->name_length);
+
+    char *name = (char *)kzalloc(target_dent->name_length + 1, 0);
+    strncpy(name, target_dent->name, target_dent->name_length);
+
+    uint32_t dentry_type = target_dent->dir_inode->attribute;
+
+    return filler(dirent, file_ptr->position - 1, name, target_dent->name_length, dentry_type, file_ptr->position - 1);
+failed:;
+    return 0;
+}
+
+static long rootfs_compare(struct vfs_dir_entry_t *parent_dEntry, char *source_filename, char *dest_filename) { return 0; }
+
+static long rootfs_hash(struct vfs_dir_entry_t *dEntry, char *filename) { return 0; }
+
+static long rootfs_release(struct vfs_dir_entry_t *dEntry) { return 0; }
+
+static long rootfs_iput(struct vfs_dir_entry_t *dEntry, struct vfs_index_node_t *inode) { return 0; }
+
+struct vfs_dir_entry_operations_t rootfs_dentry_ops =
+    {
+        .compare = &rootfs_compare,
+        .hash = &rootfs_hash,
+        .release = &rootfs_release,
+        .iput = &rootfs_iput,
+};
+
+struct vfs_file_operations_t rootfs_file_ops = {
+    .open = &rootfs_open,
+    .close = &rootfs_close,
+    .read = &rootfs_read,
+    .write = &rootfs_write,
+    .lseek = &rootfs_lseek,
+    .ioctl = &rootfs_ioctl,
+    .readdir = &rootfs_readdir,
+};
+
+/**
+ * @brief 为在rootfs下创建目录（仅仅是形式上的目录，为了支持文件系统挂载）
+ *
+ * @param name 目录名称
+ * @return int
+ */
+static int rootfs_add_dir(const char *name)
+{
+    {
+        // 检查名称重复
+        struct List *list = &rootfs_sb.root->subdirs_list;
+        while (list_next(list) != &rootfs_sb.root->subdirs_list)
+        {
+            list = list_next(list);
+            struct vfs_dir_entry_t *tmp = container_of(list, struct vfs_dir_entry_t, child_node_list);
+            if (strcmp(tmp->name, name) == 0)
+                return -EEXIST;
+        }
+    }
+
+    struct vfs_dir_entry_t *dentry = vfs_alloc_dentry(strlen(name) + 1);
+    strcpy(dentry->name, name);
+    dentry->name_length = strlen(name);
+    dentry->parent = rootfs_sb.root;
+    list_append(&rootfs_sb.root->subdirs_list, &dentry->child_node_list);
+    return 0;
+}
 
 void rootfs_init()
 {
+    // 初始化超级块
+    rootfs_sb.blk_device = NULL;
+    rootfs_sb.private_sb_info = NULL;
+    rootfs_sb.sb_ops = &rootfs_sb_ops;
+    rootfs_sb.dir_ops = &rootfs_dentry_ops;
+
+    // 初始化dentry
+    rootfs_sb.root = vfs_alloc_dentry(sizeof("/"));
+    struct vfs_dir_entry_t *dentry = rootfs_sb.root;
+    strncpy(dentry->name, "/", 2);
+    dentry->name_length = 1;
+    dentry->parent = dentry;
+
+    // 初始化root inode
+    dentry->dir_inode = vfs_alloc_inode();
+    dentry->dir_inode->sb = &rootfs_sb;
+    dentry->dir_inode->inode_ops = &rootfs_inode_ops;
+    dentry->dir_inode->file_ops = &rootfs_file_ops;
+    dentry->dir_inode->attribute = VFS_IF_DIR;
+
+    // 直接将vfs的根superblock设置为rootfs的超级块
+    vfs_root_sb = &rootfs_sb;
+
+    // 创建/dev等目录的dentry（以便文件系统的mount）
+    if (rootfs_add_dir("dev") != 0)
+        kerror("create dir 'dev' in rootfs failed");
+}
+
+/**
+ * @brief 当新的根文件系统被挂载后，将原有的挂载在rootfs下的文件系统，迁移到新的根文件系统上
+ *
+ */
+static void rootfs_migrate()
+{
+    kdebug("Migrating rootfs's dentries...");
+    struct List *list = &rootfs_sb.root->subdirs_list;
+    if (unlikely(list_empty(list)))
+        return;
+    list = list_next(list);
+    while (list != &rootfs_sb.root->subdirs_list)
+    {
+
+        struct vfs_dir_entry_t *tmp = container_of(list, struct vfs_dir_entry_t, child_node_list);
+        if (tmp->dir_inode != NULL)
+        {
+            list = list_next(list); // 获取下一个列表结点（不然的话下面的几行代码就覆盖掉了正确的值了）
+
+            tmp->parent = vfs_root_sb->root;
+            list_init(&tmp->child_node_list);
+            list_append(&vfs_root_sb->root->subdirs_list, &tmp->child_node_list);
+        }
+        else
+        {
+            list = list_next(list); // 不迁移空的dentry，直接释放他们
+            list_del(&tmp->child_node_list);
+            __release_dentry(tmp);
+        }
+    }
+}
+
+/**
+ * @brief 当磁盘文件系统被成功挂载后，释放rootfs所占的空间
+ *
+ */
+void rootfs_umount()
+{
+    // 将原有的“dev”文件夹等进行迁移
+    rootfs_migrate();
+    kinfo("Umounting rootfs...");
+
+    // 遍历mount链表，删除所有父目录是rootfs的dentry
+    struct mountpoint *mp = NULL;
+    while (1)
+    {
+        mp = mount_find_mnt_list_by_parent(rootfs_sb.root);
+        if (mp == NULL)
+            break;
+
+        // 释放dentry（由于没有创建inode，因此不需要释放）
+        __release_dentry(mp->dentry);
+        // 释放mountpoint结构体
+        mount_release_mountpoint(mp);
+    }
+
+    // 释放root dentry及其inode
+    kfree(rootfs_sb.root->dir_inode);
+    __release_dentry(rootfs_sb.root);
 }