On 02.11.2018 at 15:45 Qu Wenruo wrote: > On 2018/11/2 下午10:30, M. Klingmann wrote: >> On 31.10.2018 at 01:03 Qu Wenruo wrote: >>> My plan for such recovery is: >>> >>> 1) btrfs ins dump-super to make sure system chunk array is valid >>> 2) btrfs-find-root to find any valid chunk tree blocks >>> 3) pass that chunk tree bytenr to btrfs-restore >>> Unfortunately, btrfs-restore doesn't support specifying chunk root >>> yet. But it's pretty easy to add such support. >>> >>> So, please provide the "btrfs ins dump-super -Ffa" output to start with. >> Following your plan, I did 1) and 2). >> As 2) failed (see below), is there anything I can do to find the tree >> bytenr to supply btrfs-restore with it? >> >> 1) Here's the output given by "btrfs-show-super -Ffa": >> >> superblock: bytenr=65536, device=sdcard.iso >> --------------------------------------------------------- >> csum 0xb8e15dd7 [match] [snip] >> 2) "btrfs-find-root" yields "Couldn't read chunk root; Open ctree failed". > It's not plain "btrfs-find-root" but "btrfs-find-root -o 5". > > And you should use btrfs-progs v4.17.1, not the old v4.4. > The ability to continue search even if chunk tree get corrupted is added > in v4.5, and I strongly recommend to use latest (v4.17.1) for a lot of > fixes and extra debug output. > > If you can't find any handy way to update btrfs-progs, you could use > Archlinux iso as a rescue OS to use the latest btrfs-progs.
Using Archlinux in fact is the easiest way to use version 4.17.1 (Archlinux for 2018-11-01). Here's the output from "btrfs-find-root sdcard.iso": WARNING: cannot read chunk root, continue anyway Superblock thinks the generation is 1757933 Superblock thinks the level is 0 Here's the output using "btrfs-find-root -o 5 sdcard.iso": WARNING: cannot read chunk root, continue anyway Superblock doesn't contain generation info for root 5 Superblock doesn't contain the level info for root 5 > For 3), I could easily add such feature btrfs-restore, or just use > manually patching your superblock to continue. > So as soon as your "btrfs-find-root -o 5" gets some valid output, I > could continue the work. > Thank you. -- Mirko
signature.asc
Description: OpenPGP digital signature
