On Thu, Jun 2, 2011 at 4:48 AM, Chris Mason <chris.mason@xxxxxxxxxx> wrote: > 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 <list@xxxxxxxxx> 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. >> 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). > The tools have a command to zero out the btrfs log tree, that would have > allowed you to mount. Do you mean btrfs-zero-log? It's not compiled by default, is it? I didn't know about that until I read another thread that mentions it, and by that time I was already able to mount it. > Do you still have the busted FS? Yup. Made an image, put it in an external disk (which also use btrfs), and created a snapshot. Here's what I get using btrfs-progs-unstable tmp branch: $ btrfsck sda2.img parent transid verify failed on 44040192 wanted 38240 found 32526 parent transid verify failed on 44040192 wanted 38240 found 32526 parent transid verify failed on 44052480 wanted 38240 found 31547 parent transid verify failed on 44052480 wanted 38240 found 31547 parent transid verify failed on 44064768 wanted 38240 found 34145 parent transid verify failed on 44064768 wanted 38240 found 34145 parent transid verify failed on 44068864 wanted 38240 found 34476 parent transid verify failed on 44068864 wanted 38240 found 34476 leaf parent key incorrect 44032000 bad block 44032000 warning, start mismatch 10833383424 10833408000 Aborted $ btrfs-zero-log sda2.img parent transid verify failed on 44040192 wanted 38240 found 32526 parent transid verify failed on 44040192 wanted 38240 found 32526 parent transid verify failed on 44052480 wanted 38240 found 31547 parent transid verify failed on 44052480 wanted 38240 found 31547 parent transid verify failed on 44064768 wanted 38240 found 34145 parent transid verify failed on 44064768 wanted 38240 found 34145 parent transid verify failed on 44068864 wanted 38240 found 34476 parent transid verify failed on 44068864 wanted 38240 found 34476 After that the filesystem is mountable again, although syslog still shows this entry: Jun 2 07:50:26 HP kernel: [ 2095.290057] parent transid verify failed on 44032000 wanted 38240 found 24586 When copying some of the files, these logs appear on syslog (the same logs appear whether I use the image mounted on kernel 2.6.38-9-generic, or the one fixed with btrfs-zero-log): Jun 2 07:50:26 HP kernel: [ 2095.756842] btrfs no csum found for inode 61485 start 743616512 Jun 2 07:50:26 HP kernel: [ 2095.756950] btrfs csum failed ino 61485 extent 23713038336 csum 1645309641 wanted 0 mirror 1 What does "wanted 0" mean here? During the copy of that particular file, the system would consistently lockup at some point (there was no call trace availabe). I was able to copy it with the help of "mount -o nodatasum,ro" and "rsync --append". This particular file also appears undamaged (it's a Virtualbox disk image, and the OS & application on it ran fine). It'd be great if we can find out what's causing these errors, but for the time being I'm happy enough to get my data back :D Thanks, Fajar -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
