Clean up old test data as needed.

If run without `-m` (explicit mkfs) in subsequent testing, old test
data files may break several tests. Most failures are -EEXIST, but
there are some more subtle ones.

This change erases any existing test dir as needed just before we
run the tests, and avoids the issue entirely.

I considered doing a `mv dir dir.$$ && rm -rf dir.$$ &` alternative
solution but that likely will interfere disproportionally with
tests that do disconnects and other thing that can be impacted by an
unlink storm.

This has an obvious performance aspect - tests will be a little
slower to start on subsequent runs. In CI, this will effectively be
a no-op though.

Signed-off-by: Auke Kok <auke.kok@versity.com>

tests/run-tests.sh

@@ -532,12 +532,15 @@ for t in $tests; do
 	cmd rm -rf "$T_TMPDIR"
 	cmd mkdir -p "$T_TMPDIR"
 
-	# create a test name dir in the fs
+	# create a test name dir in the fs, clean up old data as needed
 	T_DS=""
 	for i in $(seq 0 $((T_NR_MOUNTS - 1))); do
 		dir="${T_M[$i]}/test/$test_name"
 
-		test $i == 0 && cmd mkdir -p "$dir"
+		test $i == 0 && (
+			test -d "$dir" && cmd rm -rf "$dir"
+			cmd mkdir -p "$dir"
+		)
 
 		eval T_D$i=$dir
 		T_D[$i]=$dir