Good day. Since 5.0 btrfs supports swap files. Does it support hibernation into a swap file?
With kernel version 5.0.10 (archlinux) and btrfs-progs 4.20.2 (unlikely to be relevant, but still) when I try to hibernate with systemctl or by directly manipulating '/sys/power/resume' and '/sys/power/resume_offset', the kernel logs: PM: Cannot find swap device, try swapon -a PM: Cannot get swap writer After digging into this issue I suspect that currently btrfs does not support hibernation into swap file (or does it?). Furthermore, I suspect that kernel mechanism of accessing swap file via 'resume_offset' is unreliable in btrfs case because it is more likely (comparing to other fs) to move files across filesystem which invalidates swap file offset, so the whole idea is dubious. So, 1) does btrfs supports hibernation into swap file? 2) is there mechanism to lock swap file? Best regards, Maxim Fomin
