[PATCH] btrfs/zoned: test premature ENOSPC because of reclaim being too slow

[Johannes Thumshirn <johannes.thumshirn@wdc.com>]

Add a test writing a file of 60% the drive size on a zoned btrfs and then
overwriting the file again.

On fast drives this will cause premature ENOSPC because the reclaim
process isn't triggered fast enough.

The kernel patch for this issue is:
 btrfs: zoned: wake up cleaner sooner if needed

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 tests/btrfs/310     | 54 +++++++++++++++++++++++++++++++++++++++++++++
 tests/btrfs/310.out |  2 ++
 2 files changed, 56 insertions(+)
 create mode 100755 tests/btrfs/310
 create mode 100644 tests/btrfs/310.out

diff --git a/tests/btrfs/310 b/tests/btrfs/310
new file mode 100755
index 000000000000..6f6f5542f73f
--- /dev/null
+++ b/tests/btrfs/310
@@ -0,0 +1,54 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2024 Western Digital Corporation.  All Rights Reserved.
+#
+# FS QA Test 310
+#
+# Write a single file with 60% disk size to a zoned btrfs and then overwrite
+# it again. On kernels without the fix this results in ENOSPC.
+#
+# This issue is fixed by the following kernel patch:
+#    btrfs: zoned: wake up cleaner sooner if needed
+
+. ./common/preamble
+_begin_fstest auto enospc rw zone
+
+# real QA test starts here
+
+_supported_fs btrfs
+_require_scratch
+_require_zoned_device "$SCRATCH_DEV"
+
+devsize=$(cat /sys/block/$(_short_dev $SCRATCH_DEV)/size)
+devsize=$(expr $devsize \* 512)
+filesize=$(expr $devsize \* 60 / 100)
+
+fio_config=$tmp.fio
+
+# Override the default cleanup function.
+_cleanup()
+{
+	rm -f $tmp.*
+}
+
+cat >$fio_config <<EOF
+[test]
+filename=$SCRATCH_MNT/test
+readwrite=write
+loops=2
+filesize=$filesize
+EOF
+
+_require_fio $fio_config
+
+_scratch_mkfs >/dev/null 2>&1
+_scratch_mount
+
+$FIO_PROG $fio_config >> $seqres.full
+
+_scratch_unmount
+
+echo "Silence is golden"
+# success, all done
+status=0
+exit
diff --git a/tests/btrfs/310.out b/tests/btrfs/310.out
new file mode 100644
index 000000000000..7b9eaf78a07a
--- /dev/null
+++ b/tests/btrfs/310.out
@@ -0,0 +1,2 @@
+QA output created by 310
+Silence is golden
-- 
2.43.0