260: Check proper FITRIM argument handling

260: Check proper FITRIM argument handling

This test suppose to validate that file systems are using the fitrim
arguments right. It checks that the fstrim returns EINVAl in case that
the start of the range is beyond the end of the file system, and also
that the fstrim works without an error if the length of the range is
bigger than the file system (it should be truncated to the file system
length automatically within the fitrim implementation).

This test should also catch common problem with overflow of start+len.
Some file systems (ext4,xfs) had overflow problems in the past so there
is a specific test for it (for ext4 and xfs) as well as generic test for
other file systems, but it would be nice if other fs can add their
specific checks if this problem does apply to them as well.

[Added call to _require_math. -Alex]

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>