[PATCH 0/10] xfstests: rework large filesystem testing

[Dave Chinner <david@xxxxxxxxxxxxx>]

This is a resend of a series that has been sitting inmy local
workarea for months. It reworks the large filesystem testing
infrastructure for XFS to allow it to use xfs_repair by switching
the filesystem filling to using preallocation rather than xfs_db
hacks.

It also introduces support for ext4 testing, also via preallocation
to fill the filesystem. btrfs isn't yet supported because I haven't
worked out how to reliably get the size of the filesystem and
calculate how much space is actually available in it.