initial version

code/lab8/kern/fs/vfs/vfs.c

@@ -0,0 +1,97 @@
+#include <defs.h>
+#include <stdio.h>
+#include <string.h>
+#include <vfs.h>
+#include <inode.h>
+#include <sem.h>
+#include <kmalloc.h>
+#include <error.h>
+
+static semaphore_t bootfs_sem;
+static struct inode *bootfs_node = NULL;
+
+extern void vfs_devlist_init(void);
+
+// __alloc_fs - allocate memory for fs, and set fs type
+struct fs *
+__alloc_fs(int type) {
+    struct fs *fs;
+    if ((fs = kmalloc(sizeof(struct fs))) != NULL) {
+        fs->fs_type = type;
+    }
+    return fs;
+}
+
+// vfs_init -  vfs initialize
+void
+vfs_init(void) {
+    sem_init(&bootfs_sem, 1);
+    vfs_devlist_init();
+}
+
+// lock_bootfs - lock  for bootfs
+static void
+lock_bootfs(void) {
+    down(&bootfs_sem);
+}
+// ulock_bootfs - ulock for bootfs
+static void
+unlock_bootfs(void) {
+    up(&bootfs_sem);
+}
+
+// change_bootfs - set the new fs inode 
+static void
+change_bootfs(struct inode *node) {
+    struct inode *old;
+    lock_bootfs();
+    {
+        old = bootfs_node, bootfs_node = node;
+    }
+    unlock_bootfs();
+    if (old != NULL) {
+        vop_ref_dec(old);
+    }
+}
+
+// vfs_set_bootfs - change the dir of file system
+int
+vfs_set_bootfs(char *fsname) {
+    struct inode *node = NULL;
+    if (fsname != NULL) {
+        char *s;
+        if ((s = strchr(fsname, ':')) == NULL || s[1] != '\0') {
+            return -E_INVAL;
+        }
+        int ret;
+        if ((ret = vfs_chdir(fsname)) != 0) {
+            return ret;
+        }
+        if ((ret = vfs_get_curdir(&node)) != 0) {
+            return ret;
+        }
+    }
+    change_bootfs(node);
+    return 0;
+}
+
+// vfs_get_bootfs - get the inode of bootfs
+int
+vfs_get_bootfs(struct inode **node_store) {
+    struct inode *node = NULL;
+    if (bootfs_node != NULL) {
+        lock_bootfs();
+        {
+            if ((node = bootfs_node) != NULL) {
+                vop_ref_inc(bootfs_node);
+            }
+        }
+        unlock_bootfs();
+    }
+    if (node == NULL) {
+        return -E_NOENT;
+    }
+    *node_store = node;
+    return 0;
+}
+