First 128KB of XFS partition is NULL.

[Eric Sandeen]

On 2/19/11 8:45 PM, Ajeet Yadav wrote:
> Testing team provides a very little information, but after checking
> all possiblity I cam to conclusion that he may have removed the USB
> during formating when mkfs.xfs just finished "Zero out the beginning
> of the device, to obliterate any old filesystem signatures out there"

That sounds plausible...

Just for reference, there are runtime checks to be sure we don't overwrite
block zero due to bad mappings; see "Access to block zero" message in
xfs_cmn_err_fsblock_zero() and xfs_bmap_search_extents()

-Eric