tests/qemu-iotests/005: Add a sanity check for large sparse file support

"check -raw 005" fails when running on certain filesystems - these do not
support such large sparse files. Use the same check as in test 220 to
skip the test in this case.
Suggested-by: NEric Blake <eblake@redhat.com>
Message-Id: <20190502084506.8009-2-thuth@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NAlex Bennée <alex.bennee@linaro.org>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Signed-off-by: NThomas Huth <thuth@redhat.com>

tests/qemu-iotests/005

@@ -55,6 +55,15 @@ if [ "$IMGPROTO" = "sheepdog" ]; then
     _notrun "image protocol $IMGPROTO does not support large image sizes"
 fi
 
+# Sanity check: For raw, we require a file system that permits the creation
+# of a HUGE (but very sparse) file. Check we can create it before continuing.
+if [ "$IMGFMT" = "raw" ]; then
+    if ! truncate --size=5T "$TEST_IMG"; then
+        _notrun "file system on $TEST_DIR does not support large enough files"
+    fi
+    rm "$TEST_IMG"
+fi
+
 echo
 echo "creating large image"
 _make_test_img 5000G