Package: btrfs-progs Version: 5.7-1 Followup-For: Bug #955413 Thanks for looking into it. I agree with your analysis but the issue is real. I think the long mount times tend to occur when there are large numbers of subvolumes and other large trees.
Although the problem is not fixable in btrfs-progs, I think it needs a NEWS item in btrfs-progs - otherwise many people who use btrfs disks will hit big problems after their Debian upgrade with no idea what the problem is or how they can fix it. I think including the NEWS text I proposed in the btrfs-progs package would avoid problems for a significant percentage of existing Debian btrfs users.
