From mboxrd@z Thu Jan  1 00:00:00 1970
From: <dsmith@tgen.org>
Subject: FS won't mount, open_ctree failed, Assertion !(path->slots[0] == 0)
 failed
Date: Wed, 7 Dec 2011 02:39:31 +0000
Message-ID: <CB041FF1.1FD66%dsmith@tgen.org>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Cc: <dsmith@tgen.org>
To: <linux-btrfs@vger.kernel.org>
Return-path: <linux-btrfs-owner@vger.kernel.org>
List-ID: <linux-btrfs.vger.kernel.org>

So I'm having a bit of trouble with one of my btrfs filesystems.  It isn't mounting after a power failure.  I can't get restore or btrfsck to run, even on backup supers.  I've pasted some output below.  My btrfs-progs below come from git this morning, running on linux 3.2.0.

# mount /dev/md2 /media/test/
mount: wrong fs type, bad option, bad superblock on /dev/md2,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

dmesg:
[26423.775471] device label LUMBERYARD devid 1 transid 1268960 /dev/md2
[26423.860966] parent transid verify failed on 25487586828288 wanted 1268960 found 1246404
[26423.860974] parent transid verify failed on 25487586828288 wanted 1268960 found 1246404
[26423.860979] parent transid verify failed on 25487586828288 wanted 1268960 found 1246404
[26423.872936] btrfs: open_ctree failed

# ./btrfsck /dev/md2
parent transid verify failed on 25487586828288 wanted 1268960 found 1246404
parent transid verify failed on 25487586828288 wanted 1268960 found 1246404
parent transid verify failed on 25487586828288 wanted 1268960 found 1246404
parent transid verify failed on 25487586828288 wanted 1268960 found 1246404
Ignoring transid failure
btrfsck: root-tree.c:46: btrfs_find_last_root: Assertion `!(path->slots[0] == 0)' failed.
Aborted
# ./btrfsck -s 1 /dev/md2
using SB copy 1, bytenr 67108864
parent transid verify failed on 25483242758144 wanted 1268944 found 1268949
parent transid verify failed on 25483242758144 wanted 1268944 found 1268949
parent transid verify failed on 25483242758144 wanted 1268944 found 1268957
parent transid verify failed on 25483242758144 wanted 1268944 found 1268957
Ignoring transid failure
btrfsck: root-tree.c:46: btrfs_find_last_root: Assertion `!(path->slots[0] == 0)' failed.
Aborted
# ./btrfsck -s 2 /dev/md2
using SB copy 2, bytenr 274877906944
parent transid verify failed on 25483242758144 wanted 1268944 found 1268949
parent transid verify failed on 25483242758144 wanted 1268944 found 1268949
parent transid verify failed on 25483242758144 wanted 1268944 found 1268957
parent transid verify failed on 25483242758144 wanted 1268944 found 1268957
Ignoring transid failure
btrfsck: root-tree.c:46: btrfs_find_last_root: Assertion `!(path->slots[0] == 0)' failed.
Aborted

# ./find-root /dev/md2
http://pastebin.com/3umfQHhh

# ./restore -i -f 25483145760768 /dev/md2 /tmp
parent transid verify failed on 25487586828288 wanted 1268960 found 1246404
parent transid verify failed on 25487586828288 wanted 1268960 found 1246404
parent transid verify failed on 25487586828288 wanted 1268960 found 1246404
parent transid verify failed on 25487586828288 wanted 1268960 found 1246404
Ignoring transid failure
restore: root-tree.c:46: btrfs_find_last_root: Assertion `!(path->slots[0] == 0)' failed.
Aborted
# ./restore -i -u 1 /dev/md2 /tmp
parent transid verify failed on 25483242758144 wanted 1268944 found 1268949
parent transid verify failed on 25483242758144 wanted 1268944 found 1268949
parent transid verify failed on 25483242758144 wanted 1268944 found 1268957
parent transid verify failed on 25483242758144 wanted 1268944 found 1268957
Ignoring transid failure
restore: root-tree.c:46: btrfs_find_last_root: Assertion `!(path->slots[0] == 0)' failed.
Aborted
# ./restore -i -u 1 -f 25483145760768 /dev/md2 /tmp
parent transid verify failed on 25483242758144 wanted 1268944 found 1268949
parent transid verify failed on 25483242758144 wanted 1268944 found 1268949
parent transid verify failed on 25483242758144 wanted 1268944 found 1268957
parent transid verify failed on 25483242758144 wanted 1268944 found 1268957
Ignoring transid failure
restore: root-tree.c:46: btrfs_find_last_root: Assertion `!(path->slots[0] == 0)' failed.
Aborted

All further restores with various combinations of superblocks and bytenr's I tried produced output identical to one of the restores above.

As the newest data on this filesystem had not been backed up, it would be nice if I could either return the filesystem to a mountable state, or recover specific files to another filesystem.  Any ideas?

-- David Smith