xfs_repair breaks; xfs_metadump hangs

[mill / in-medias-res]

Hello XFS-Community,

i have some real trouble with restoring/repairing my two XFS Partion's. These
Partion's are on a RAID-5 Array which "was broken". The first xfs_repair run
on /dev/sdc1 did restore 80 GB from ca. 300-400 GB. The Problem was that 99,9%
of the million files are in lost+found.

Because i was more interested in restoring /dev/sdc2, i did forget about sdc1
and run xfs_repair on the other Partion:

cmd: xfs_repair -t 1 -P /dev/sdc2
[...]
corrupt inode 3256930831 ((a)extents = 1).  This is a bug.
Please capture the filesystem metadata with xfs_metadump and
report it to xfs at oss.sgi.com.
cache_node_purge: refcount was 1, not zero (node=0x377d0008)
fatal error -- couldn't map inode 3256930831, err = 117

time: 67,27s user 10,09s system 10% cpu 12:05,31 total

I tried to run xfs_metadump serveral times and it hangs everytime on this position:
xfs_metadump  -g /dev/sdc2 metadump-sdc2-2
Copied 1411840 of 4835520 inodes (0 of 3 AGs)

It runs till 2 days on the same inode and xfs_db consumes 99% of CPU.
Should i wait here?

Versions:
dpkg -l |grep xfs
ii  xfsdump   3.0.2~bpo50+1       Administrative utilities for the XFS filesys
ii  xfsprogs  3.0.4~bpo50+1       Utilities for managing the XFS filesystem
Distribution: Debian lenny with xfsprogs, xfsdump backport from unstable.

The xfs_repair with stock Debian Lenny version also does crash at inode 3256930831.

Best Regards,
Maximilian Mill