vfs: properly sync metadata

kernel-src/fs/ext2.c

@@ -2178,8 +2178,15 @@ static int ext2_mount(vfs_t **vfs, vnode_t *mountpoint, vnode_t *backing, void *
 	return err;
 }
 
+static int ext2_syncfs(vfs_t *vfs) {
+	ext2fs_t *fs = (ext2fs_t *)vfs;
+	abc_sync(&fs->abc);
+	return error;
+}
+
 static vfsops_t vfsops = {
 	.mount = ext2_mount,
+	.sync = ext2_syncfs,
 	.root = ext2_root,
 	.statfs = ext2_statfs
 };

kernel-src/fs/vfs.c

@@ -136,6 +136,21 @@ int vfs_register(vfsops_t *ops, char *name) {
 	return hashtable_set(&fstable, ops, name, strlen(name), true);
 }
 
+int vfs_sync(void) {
+	int error = mm_cache_sync();
+
+	MUTEX_ACQUIRE(&listlock);
+	for (vfs_t *vfs = vfslist; vfs; vfs = vfs->next) {
+		if (vfs->ops->sync) {
+			int e = VFS_SYNC(vfs);
+			if (error == 0)
+				error = e;
+		}
+	}
+	MUTEX_RELEASE(&listlock);
+	return error;
+}
+
 void vfs_inactive(vnode_t *vnode) {
 	if (vnode->type == V_TYPE_SOCKET && vnode->socketbinding) {
 		localsock_leavebinding(vnode);

kernel-src/include/kernel/vfs.h

@@ -259,6 +259,7 @@ void advlock_free(advlock_t *advlock);
 void vfs_init();
 int vfs_mount(vnode_t *backing, vnode_t *pathref, char *path, char *name, void *data);
 int vfs_register(vfsops_t *vfsops, char *name);
+int vfs_sync(void);
 
 void vfs_root_event_signal(void);
 int vfs_root_event_attach(void (*fn)(void *), void *ctx);

kernel-src/sys/syscalls/sync.c

@@ -3,7 +3,8 @@
 
 syscallret_t syscall_sync(context_t *) {
 	syscallret_t ret = {0};
-	mm_cache_sync();
+	ret.errno = vfs_sync();
+	ret.ret = ret.errno ? -1 : 0;
 	return ret;
 }