lvm/luks/btrfs и trim

deus-vult% cat /etc/lvm/lvm.conf| grep issue_discards
	# Configuration option devices/issue_discards.
	issue_discards = 1

deus-vult% cat /etc/fstab| grep discard              
UUID=b07879f5-e3a0-4ae8-a523-1ba7b0b4478c	/         	btrfs     	discard,rw,noatime,compress=lzo,ssd,space_cache,subvolid=257,subvol=/root,subvol=root	0 0
UUID=d969d253-caf1-4e44-b38d-b435ad1c444c	/home     	btrfs     	discard,rw,noatime,compress=lzo,ssd,space_cache,subvolid=256,subvol=/home,subvol=home	0 0

deus-vult% systemctl status fstrim.timer             
● fstrim.timer - Discard unused blocks once a week
   Loaded: loaded (/usr/lib/systemd/system/fstrim.timer; enabled; vendor preset: disabled)
   Active: active (waiting) since Tue 2017-04-25 22:38:14 MSK; 3min 6s ago
     Docs: man:fstrim

Apr 25 22:38:14 deus-vult systemd[1]: Started Discard unused blocks once a week.

deus-vult% cat /boot/loader/entries/arch.conf| grep discard
options cryptdevice=UUID=46294c16-422f-4f34-a53a-2b93fe09ff41:sda2_crypt:allow-discards root=/dev/mapper/rootvg-rootlv rootflags=subvol=root rw

deus-vult% sudo fstrim -v /
fstrim: /: the discard operation is not supported

deus-vult% lsblk -o NAME,MOUNTPOINT,DISC-MAX
NAME                MOUNTPOINT DISC-MAX
sda                                  0B
├─sda1              /boot            0B
└─sda2                               0B
  └─sda2_crypt                       0B
    ├─rootvg-rootlv /                0B
    └─rootvg-homelv /home            0B
sr0                                  0B
deus-vult%

deus-vult% sudo mkfs.btrfs -f /dev/sdb1| grep detected
SSD detected:       yes
deus-vult%

[~]$ cat /etc/default/grub | grep -oE 'cryptdevice=.*:allow-discards'
cryptdevice=/dev/md0:system:allow-discards

[~]$ cat /etc/lvm/lvm.conf | grep issue_discards
        # Configuration option devices/issue_discards.
        issue_discards = 1

[~]$ cat /etc/fstab | grep btrfs | head -n 1 | grep -oE 'rw,.*,discard'
rw,relatime,space_cache=v2,ssd,discard