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
