Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > Umm... That's going to be very painful if you dup2() something to MAX_INT and > then run that; roughly 2G iterations of bouncing ->file_lock up and down, > without anything that would yield CPU in process. > > If anything, I would suggest something like > > fd = *start_fd; > grab the lock > fdt = files_fdtable(files); > more: > look for the next eviction candidate in ->open_fds, starting at fd > if there's none up to max_fd > drop the lock > return NULL > *start_fd = fd + 1; > if the fscker is really opened and not just reserved > rcu_assign_pointer(fdt->fd[fd], NULL); > __put_unused_fd(files, fd); > drop the lock > return the file we'd got > if (unlikely(need_resched())) > drop lock > cond_resched(); > grab lock > fdt = files_fdtable(files); > goto more; > > with the main loop being basically > while ((file = pick_next(files, &start_fd, max_fd)) != NULL) > filp_close(file, files); If we can live with close_from(int first) rather than close_range(), then this can perhaps be done a lot more efficiently by: new = alloc_fdtable(first); spin_lock(&files->file_lock); old = files_fdtable(files); copy_fds(new, old, 0, first - 1); rcu_assign_pointer(files->fdt, new); spin_unlock(&files->file_lock); clear_fds(old, 0, first - 1); close_fdt_from(old, first); kfree_rcu(old); David
