On Tue, May 21, 2019 at 08:20:09PM +0100, Al Viro wrote: > On Tue, May 21, 2019 at 05:30:27PM +0100, David Howells wrote: > > > 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); > > I really hate to think how that would interact with POSIX locks... POSIX locks store current->files in fl_owner; David's resizing the underlying files->fdt, just like growing from 64 to 256 fds.
