Add t_require_meta_size function

Add a function that tests can use to skip when the metadata device isn't
large enough.  I thought we needed to avoid enospc in a particular test,
but it turns out the test's failure was unrelated.  So this isn't used
for now but it seems nice to keep around.

Signed-off-by: Zach Brown <zab@versity.com>

tests/funcs/require.sh

@@ -23,3 +23,18 @@ t_require_mounts() {
 	test "$T_NR_MOUNTS" -ge "$req" || \
 		t_skip "$req mounts required, only have $T_NR_MOUNTS"
 }
+
+#
+# Require that the meta device be at least the size string argument, as
+# parsed by numfmt using single char base 2 suffixes (iec).. 64G, etc.
+#
+t_require_meta_size() {
+	local dev="$T_META_DEVICE"
+	local req_iec="$1"
+	local req_bytes=$(numfmt --from=iec --to=none $req_iec)
+	local dev_bytes=$(blockdev --getsize64 $dev)
+	local dev_iec=$(numfmt --from=auto --to=iec $dev_bytes)
+
+	test "$dev_bytes" -ge "$req_bytes" || \
+		t_skip "$dev must be at least $req_iec, is $dev_iec"
+}