df bigger than ls?

[Brian Candler]

On Thu, Mar 08, 2012 at 08:50:35AM +0000, Brian Candler wrote:
> Aha.  This may well be what is screwing up gluster's disk usage on a striped
> volume - I believe XFS is preallocating space which is actually going to end
> up being a hole!

Here is a standalone testcase.

$ for i in {0..19}; do dd if=/dev/zero of=testfile bs=128k count=1 seek=$[$i * 12]; done
$ xfs_bmap testfile
testfile:
	0: [0..255]: 1465133392..1465133647
	1: [256..3071]: hole
	2: [3072..5119]: 1465136464..1465138511
	3: [5120..6143]: hole
	4: [6144..10239]: 1465139536..1465143631
	5: [10240..12287]: hole
	6: [12288..20479]: 1465145680..1465153871
	7: [20480..21503]: hole
	8: [21504..37887]: 1465154896..1465171279
	9: [37888..39935]: hole
	10: [39936..58623]: 1465173328..1465192015

I expected to see: 20 extents of 256 blocks and 19 holes of 2816 blocks.

Regards,

Brian.