On Tue, Mar 27, 2018 at 7:13 AM, David Sterba <dste...@suse.cz> wrote: > On Mon, Mar 26, 2018 at 10:00:04AM -0500, Ashu Tiwary wrote: >> It appears my system may have hit the issue reverted here ( >> https://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg74621.html >> ) ( [PATCH] Revert "btrfs: use proper endianness accessors for >> super_copy" ); system is an IBM OpenPower 720 (Big Endian) running >> Fedora 27; kernel was at 4.15.9; attempting to reboot after updating >> system (including kernel to 4.15.10) caused system to not be able to >> boot: >> >> ===== >> Mounting /sysroot... >> [ 34.644721] BTRFS warning (device dm-3): suspicious: generation < >> chunk_root_generation: 15959351903540740096 < 17261735521269317632 >> [ 34.644761] BTRFS info (device dm-3): disk space caching is enabled >> [ 34.644771] BTRFS info (device dm-3): has skinny extents >> [ 34.645925] BTRFS critical (device dm-3): unable to find logical >> 71472550772736 length 65536 >> [ 34.645941] BTRFS critical (device dm-3): unable to find logical >> 71472550772736 length 65536 >> [ 34.645952] BTRFS error (device dm-3): failed to read chunk root >> [ 34.807156] BTRFS error (device dm-3): open_ctree failed >> [FAILED] Failed to mount /sysroot. >> ===== >> >> It appears there is a manual method available to repair the corrupted >> superblock: can that be made available? > > Yes, details below. > > Quick check from your logs: > > chunk_root_generation: 15959351903540740096 = 0xdd7b020000000000 > should be: 162781 = 0x0x27bdd > > tree root block pointer: 71472550772736 = 0x410100000000 > should be: 21037056 = 0x1410000 > > The tool is available in the branch devel in my repos. Setup repository > unless you already have one: > > $ git clone git://github.com/kdave/btrfs-progs > $ cd btrfs-progs > $ git checkout devel > $ ./autogen.sh > $ ./configure > > Build the tool: > > $ make btrfs-sb-mod > > Use it (replace the path with the real one) and save the output in case > something goes unexpectedly wrong: > > device=/path/to/the/device > ./btrfs-sb-mod $device root @0 > ./btrfs-sb-mod $device generation @0 > ./btrfs-sb-mod $device chunk_root @0 > ./btrfs-sb-mod $device chunk_root_generation @0 > ./btrfs-sb-mod $device cache_generation @0 > ./btrfs-sb-mod $device uuid_tree_generation @0 > > It prints the current and new values so it's reversible, besides that > the byteswap can be run twice to get back to the starting point. > > Then the filesystem should be mountable again.
Hi, That utility worked perfectly (it took me some time as I had to find another system on which to build the recovery tool). Thanks, -Ashu -- Ashu Tiwary ashuat...@gmail.com -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
