Hi, Somehow my btrfs partition got broken. I use Arch, so my kernel is quite new (4.18.x). I don't remember exactly the sequence of events. At some point it was accessible in read-only, but unfortunately I did not take backup immediately. dmesg log from that time: [ 62.602388] BTRFS warning (device nvme0n1p2): block group 103923318784 has wrong amount of free space [ 62.602390] BTRFS warning (device nvme0n1p2): failed to load free space cache for block group 103923318784, rebuilding it now [ 108.039188] BTRFS error (device nvme0n1p2): bad tree block start 0 18812026880 [ 108.039227] BTRFS: error (device nvme0n1p2) in __btrfs_free_extent:7010: errno=-5 IO failure [ 108.039241] BTRFS info (device nvme0n1p2): forced readonly [ 108.039250] BTRFS: error (device nvme0n1p2) in btrfs_run_delayed_refs:3076: errno=-5 IO failure At the next reboot it failed to mount. Problem may have been that at some point I booted to another distro with older kernel (4.15.x, 4.14.52) and unfortunately attempted some checks/repairs (?) e.g. from gparted, and at that time I did not know it could be destructive. Anyway, currently it fails to mount (even with ro and/or recovery), btrfs check results in "checksum verify failed" and "bad tree block" errors, btrfs restore resulted in "We have looped trying to restore files in" errors for a dozen of paths then exit. Is there some hope to save data from the filesystem, and if so, how? BTW I checked some diagnostics commands regarding my SSD with the nvme client and from that it seems there are no hardware problems. Your help is highly appreciated. Cheers, Attila
