btrfs-progs: tests: mkfs and extra large devices

Test case for mkfs to handle if total device size overflows 16EiB. The
device images are created inside temporary btrfs so this works on any
underlying filesystem (unlike NFS or tmpfs).

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
[ split test from original patch and update to work on any filesystem ]
Signed-off-by: David Sterba <dsterba@suse.com>

tests/mkfs-tests/018-multidevice-overflow/test.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+# test if mkfs.btrfs will create file systems that overflow total_bytes
+
+source "$TEST_TOP/common"
+
+check_prereq mkfs.btrfs
+check_prereq btrfs
+
+setup_root_helper
+prepare_test_dev
+
+# create a temporary btrfs filesystem for the images to make sure the
+# exabyte-scale files will be reliably created
+run_check_mkfs_test_dev
+run_check_mount_test_dev
+
+run_check $SUDO_HELPER truncate -s 6E "$TEST_MNT/img1"
+run_check $SUDO_HELPER truncate -s 6E "$TEST_MNT/img2"
+run_check $SUDO_HELPER truncate -s 6E "$TEST_MNT/img3"
+
+run_mustfail "mkfs for too-large images" \
+	$SUDO_HELPER "$TOP/mkfs.btrfs" -f "$TEST_MNT"/img[123]
+
+run_check_umount_test_dev