Спасибо огромное.
Перезагрузил пк - своп на месте.
~$ mount|grep btrfs
/dev/sda2 on / type btrfs (rw,relatime,ssd,space_cache,subvolid=435,subvol=/@)
/dev/sda2 on /swap type btrfs (rw,relatime,ssd,space_cache,subvolid=418,subvol=/@swap)
/dev/sda3 on /home type btrfs (rw,relatime,ssd,space_cache,subvolid=257,subvol=/@home)
~$ sudo ls -l /swap/swapfile
[sudo] пароль до masterok:
-rw------- 1 root root 4294967296 бер 12 22:05 /swap/swapfile
~$ sudo swapon --show
NAME TYPE SIZE USED PRIO
/swap/swapfile file 4G 0B -2
~$ sudo free -h
загалом використ. вільна спільна буфери/кеш дост.
Пам.: 7,7G 2,0G 4,4G 121M 1,3G 5,3G
Своп.: 4,0G 0B 4,0G
~$ sudo lsattr /swap/swapfile
---------------C-- /swap/swapfile
~$ egrep -v '^$|^#' /etc/fstab
UUID=d446f37a-e89f-40da-ba2c-8e2c9de94bcb / btrfs defaults,subvol=@ 0 1
UUID=590A-F791 /boot/efi vfat umask=0077 0 1
UUID=23e17ef7-2d66-42b5-8cb2-fa6f033936d7 /home btrfs defaults,subvol=@home 0 2
/dev/disk/by-uuid/a64d97b2-f858-4342-a6c2-e4921f81ef0a /media/Files auto nosuid,nodev,nofail,x-gvfs-show 0 0
UUID=d446f37a-e89f-40da-ba2c-8e2c9de94bcb /swap btrfs subvol=@swap 0 0
/swap/swapfile none swap sw 0 0
~$ mount | grep /sd
/dev/sda2 on / type btrfs (rw,relatime,ssd,space_cache,subvolid=435,subvol=/@)
/dev/sda2 on /swap type btrfs (rw,relatime,ssd,space_cache,subvolid=418,subvol=/@swap)
/dev/sda1 on /boot/efi type vfat (rw,relatime,fmask=0077,dmask=0077,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)
/dev/sda3 on /home type btrfs (rw,relatime,ssd,space_cache,subvolid=257,subvol=/@home)
/dev/sdb6 on /media/Files type ext4 (rw,nosuid,nodev,relatime,x-gvfs-show)
/dev/sdb3 on /media/masterok/0190e2d6-de62-4ee2-92d6-b0913ff8654f type ext4 (rw,nosuid,nodev,relatime,uhelper=udisks2)
/dev/sdb5 on /media/masterok/5a7637d7-d2a4-4424-b4dc-816a17809ccc type ext4 (rw,nosuid,nodev,relatime,uhelper=udisks2)
/dev/sdb4 on /media/masterok/e3749f83-0dfe-45e7-b6fd-c533c8a9c52a type ext4 (rw,nosuid,nodev,relatime,uhelper=udisks2)
~$ lsblk -o +UUID
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT UUID
sda 8:0 0 223,6G 0 disk
├─sda1 8:1 0 476M 0 part /boot/efi 590A-F791
├─sda2 8:2 0 95,4G 0 part /swap d446f37a-e89f-40da-ba2c-8e2c9de94bcb
└─sda3 8:3 0 127,8G 0 part /home 23e17ef7-2d66-42b5-8cb2-fa6f033936d7
sdb 8:16 0 1,8T 0 disk
├─sdb1 8:17 0 477M 0 part 96FC-5ED6
├─sdb2 8:18 0 9,3G 0 part f798f26a-647f-4c64-8031-12877b19f2f3
├─sdb3 8:19 0 9,3G 0 part /media/masterok/0190e2d6-de62-4 0190e2d6-de62-4ee2-92d6-b0913ff8654f
├─sdb4 8:20 0 46,6G 0 part /media/masterok/e3749f83-0dfe-4 e3749f83-0dfe-45e7-b6fd-c533c8a9c52a
├─sdb5 8:21 0 46,6G 0 part /media/masterok/5a7637d7-d2a4-4 5a7637d7-d2a4-4424-b4dc-816a17809ccc
└─sdb6 8:22 0 1,7T 0 part /media/Files a64d97b2-f858-4342-a6c2-e4921f81ef0a
sr0 11:0 1 1024M 0 rom
~$ sudo btrfs sub list /
ID 418 gen 36047 top level 5 path @swap
ID 423 gen 35895 top level 5 path timeshift-btrfs/snapshots/2020-01-28_20-38-11/@
ID 434 gen 35895 top level 5 path timeshift-btrfs/snapshots/2020-03-05_22-05-46/@
ID 435 gen 36071 top level 5 path @