Bug#1064624: Hard to short-stroke an encrypted drive

[Pascal Hambourg <pascal@plouf.fr.eu.org>]

On 26/02/2024 at 01:14, Matthew Wilcox wrote:
> > - create a logical volume in the free VG space
> > - blkdiscard the logical volume
>
> Last time I checked, dm-crypt did not pass DISCARD requests through to
> the underlying device because it's a security hazard.

AFAICS dm-crypt and cryptsetup have supported discard since Linux 3.1.

crypttab(5) states that "starting with Debian 10 (Buster), this option 
is added per default to new dm-crypt devices by the Debian Installer".

Discard can still be disabled at the filesystem or swap level, or you 
can disable dm-crypt discard after running blkdiscard.