Excerpts from Fajar A. Nugraha's message of 2011-06-01 08:22:40 -0400: > On Wed, Jun 1, 2011 at 6:06 AM, Fajar A. Nugraha <l...@fajar.net> wrote: > > While using btrfs as root on kernel 3.0-rc1, there was some errors (I > > wasn't able to capture the error) that forced me to do hard reset. > > > > Now during startup system drops to busybox shell because it's unable > > to mount root partition. > > Is there a way to recover the data, as at least grub2 was still happy > > enough to load kernel and initrd (both of which located on the same > > btrfs partition)? > > > > This is what dmesg says > > > > [ 4.536798] device label SSD-ROOT devid 1 transid 38245 /dev/sda2 > > [ 9.552086] device label SSD-ROOT devid 1 transid 38245 > > /dev/disk/by-label/SSD-ROOT > > [ 9.554563] btrfs: disk space caching is enabled > > [ 9.564301] parent transid verify failed on 44040192 wanted 38240 found > > 32526 > > [ 9.564535] parent transid verify failed on 44040192 wanted 38240 found > > 32526 > > [ 9.564778] parent transid verify failed on 44040192 wanted 38240 found > > 32526 > > [ 9.575679] parent transid verify failed on 44052480 wanted 38240 found > > 31547 > > [ 9.575904] parent transid verify failed on 44052480 wanted 38240 found > > 31547 > > [ 9.576176] parent transid verify failed on 44052480 wanted 38240 found > > 31547 > > [ 9.586121] parent transid verify failed on 44064768 wanted 38240 found > > 34145 > > [ 9.586319] parent transid verify failed on 44064768 wanted 38240 found > > 34145 > > [ 9.586515] parent transid verify failed on 44064768 wanted 38240 found > > 34145 > > [ 9.587027] parent transid verify failed on 44068864 wanted 38240 found > > 34476 > > [ 9.589732] Btrfs detected SSD devices, enabling SSD mode > > [ 9.592923] block group 29360128 has an wrong amount of free space > > [ 9.592959] btrfs: failed to load free space cache for block group > > 29360128 > > > For anyone who got the same problem, > > I was finally able to mount the fs using Ubuntu Natty's > 2.6.38-8-generic (the one on live CD). > Previously I tried using 2.6.38-9-generic and and 3.0-rc1, none works. > Now I'm copying the files somewhere else before reinstalling this > system.
The tools have a command to zero out the btrfs log tree, that would have allowed you to mount. Do you still have the busted FS? Thanks a lot for this bug report, I'll try to reproduce it. > > On another note, does anybody know how btrfs allocates ID for subvols? > It doesn't seem to reuse deleted subvol's ID. What happens when the > last subvol ID is 999? > We don't reuse the ids for subvols or snapshots, but we can have a little less than 2^64 of them. An id can be reused as long as there are no blocks with refs for it in the extent allocation tree, but that needs to be checked before we reuse it. -chris -- 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
