A recent patch series[1] adds support for calling fallocate() in mode 0
on block devices. This test adds a basic sanity test for loopback devices
setup on a sparse file and validates that writes to the loopback device
succeed, even when the underlying filesystem runs out of space.
Signed-off-by: Sarthak Kukreti <sarthakkukreti@xxxxxxxxxxxx>
---
tests/loop/010 | 60 ++++++++++++++++++++++++++++++++++++++++++++++
tests/loop/010.out | 2 ++
2 files changed, 62 insertions(+)
create mode 100644 tests/loop/010
create mode 100644 tests/loop/010.out
diff --git a/tests/loop/010 b/tests/loop/010
new file mode 100644
index 0000000..091be5e
--- /dev/null
+++ b/tests/loop/010
@@ -0,0 +1,60 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-3.0+
+# Copyright (C) 2023 Google LLC.
+# Author: sarthakkukret@xxxxxxxxxx (Sarthak Kukreti)
+#
+# Test if fallocate() on a loopback device provisions space on the underlying
+# filesystem and writes on the loop device succeed, even if the lower
+# filesystem is filled up.
+
+. tests/loop/rc
+
+DESCRIPTION="Loop device fallocate() space provisioning"
+QUICK=1
+
+requires() {
+ _have_program mkfs.ext4
+}
+
+test() {
+ echo "Running ${TEST_NAME}"
+
+ local mount_dir="$TMPDIR/mnt"
+ mkdir -p ${mount_dir}
+
+ local image_file="$TMPDIR/img"
+ truncate -s 1G "${image_file}"
+
+ local loop_device
+ loop_device="$(losetup -P -f --show "${image_file}")"
+
+ mkfs.ext4 ${loop_device} &> /dev/null
+ mount -t ext4 ${loop_device} ${mount_dir}
+
+ local provisioned_file="${mount_dir}/provisioned"
+ truncate -s 200M "${provisioned_file}"
+
+ local provisioned_loop_device
+ provisioned_loop_device="$(losetup -P -f --show "${provisioned_file}")"
+
+ # Provision space for the file: without provisioning support, this fails
+ # with EOPNOTSUPP.
+ fallocate -l 200M "${provisioned_loop_device}"
+
+ # Fill the filesystem, this command will error out with ENOSPC.
+ local fs_fill_file="${mount_dir}/fill"
+ dd if=/dev/zero of="${fs_fill_file}" bs=1M count=1024 status=none &>/dev/null
+ sync
+
+ # Write to provisioned loop device, ensure that it does not run into ENOSPC.
+ dd if=/dev/zero of="${provisioned_loop_device}" bs=1M count=200 status=none
+ sync
+
+ # Cleanup.
+ losetup --detach "${provisioned_loop_device}"
+ umount "${mount_dir}"
+ losetup --detach "${loop_device}"
+ rm "${image_file}"
+
+ echo "Test complete"
+}
\ No newline at end of file
diff --git a/tests/loop/010.out b/tests/loop/010.out
new file mode 100644
index 0000000..068c489
--- /dev/null
+++ b/tests/loop/010.out
@@ -0,0 +1,2 @@
+Running loop/009
+Test complete
--
2.42.0.758.gaed0368e0e-goog
