swalloc/allocsize question

[Joe Landman]

Hi folks:

   I've noticed some "odd" behavior while experimenting with xfs mounts 
on relatively recent kernels (3.18 series).  Basically, the 
swalloc,allocsize=x options are being modified to something different.  
That is:

root at usn-04:~/burn-in/fio# uname -r
3.18.12.scalable

root at usn-04:~/burn-in/fio# mount -o 
inode64,noatime,nodiratime,swalloc,allocsize=1280k /dev/sda /data/1

root at usn-04:~/burn-in/fio# mount | grep sda
/dev/sda on /data/1 type xfs 
(rw,noatime,nodiratime,swalloc,attr2,inode64,allocsize=256k,noquota)

This is a hardware RAID6 with a 128k chunk size and 12 elements (so 10 
data drives, thus the 1280k allocsize for stripe width allocation).  Is 
this something specific to xfs itself, or is this an issue in the mount 
tools ?

FWIW: we are using xfs-tools 3.2.2, kernel 3.18.12.  I've also seen this 
with the 3.10 series though, so I am not sure where to look to track 
this down.  Any guidance/suggestion?  Thanks!

Joe

joe.landman at gmail.com