Regression- XFS won't mount on partitioned md array

[David Greaves <david@dgreaves.com>]

I just attempted a kernel upgrade from 2.6.20.7 to 2.6.25.3 and it no longer
mounts my xfs filesystem.

I bisected it to around
a67d7c5f5d25d0b13a4dfb182697135b014fa478
[XFS] Move platform specific mount option parse out of core XFS code

I have a RAID5 array with partitions:

Partition Table for /dev/md_d0

               First       Last
 # Type       Sector      Sector   Offset    Length   Filesystem Type (ID) Flag
-- ------- ----------- ----------- ------ ----------- -------------------- ----
 1 Primary           0  2500288279      4  2500288280 Linux (83)           None
 2 Primary  2500288280  2500483583      0      195304 Non-FS data (DA)     None


when I attempt to mount /media:
/dev/md_d0p1 /media xfs rw,nobarrier,noatime,logdev=/dev/md_d0p2,allocsize=512m 0 0

I get:
 md_d0: p1 p2
XFS mounting filesystem md_d0p1
attempt to access beyond end of device
md_d0p2: rw=0, want=195311, limit=195304
I/O error in filesystem ("md_d0p1") meta-data dev md_d0p2 block 0x2fae7
("xlog_bread") error 5 buf count 512
XFS: empty log check failed
XFS: log mount/recovery failed: error 5
XFS: log mount failed

A repair:
  xfs_repair /dev/md_d0p1 -l /dev/md_d0p2
gives no errors.

Phase 1 - find and verify superblock...
Phase 2 - using external log on /dev/md_d0p2
        - zero log...
        - scan filesystem freespace and inode maps...
        - found root inode chunk
...


David