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.
