fat: Remove directory from dlist on unlink, not in remove_vnode.

The removal of the vnode happens later than the actual unlink. As part
of the unlink, the vnode cache is already updated to mark the unlinked
directory invalid. This means its entry in the directory list needs to
be removed as well. Otherwise, if a directory list entry is looked up
in the time between unlink and remove_vnode, the assertion which checks
the validity of the directory list entries would fail.

src/add-ons/kernel/file_systems/fat/file.c

@@ -1072,9 +1072,10 @@ dosfs_remove_vnode(fs_volume *_vol, fs_vnode *_node, bool reenter)
 	if (find_vnid_in_vcache(vol, node->vnid) == B_OK)
 		remove_from_vcache(vol, node->vnid);
 
-	/* and from the dlist as well */
-	if (node->mode & FAT_SUBDIR)
-		dlist_remove(vol, node->vnid);
+	/* at this point, the node shouldn't be in the dlist anymore */
+	if ((node->mode & FAT_SUBDIR) != 0) {
+		ASSERT(dlist_find(vol, CLUSTER_OF_DIR_CLUSTER_VNID(node->vnid)) == -1);
+	}
 
 	free(node);
 
@@ -1174,6 +1175,9 @@ do_unlink(fs_volume *_vol, fs_vnode *_dir, const char *name, bool is_file)
 	 */
 	vcache_set_entry(vol, file->vnid, generate_unique_vnid(vol));
 
+	if (!is_file)
+		dlist_remove(vol, file->vnid);
+
 	// fsil doesn't call dosfs_write_vnode for us, so we have to free the
 	// vnode manually here.
 	remove_vnode(_vol, file->vnid);