[PATCH] xfstests: introduce FSX_AVOID env var

[Christoph Hellwig]

On Mon, Apr 21, 2014 at 11:30:04AM -0500, Eric Sandeen wrote:
> Just like FSSTRESS_AVOID, FSX_AVOID can be used to add
> options at the end of the default fsx runs in each test.
> i.e. FSX_AVOID="-H -z -C" will disable punch hole, zero range,
> and collapse range calls in all tests which run fsx.
> 
> This should handle Ted's concerns about buggy ext4 fallocate
> code without needing to add tunables to the kernel to reject
> these operations during xfstests runs.

I would much prefer to add a little _run_fsx helper to encapsulate this.