[PATCH v2] generic: shutdown might leave NULL files with nonzero di_size

[Zorro Lang <zlang@kernel.org>]

An old issue might cause on-disk inode sizes are logged prematurely
via the free eofblocks path on file close. Then fs shutdown might
leave NULL files but their di_size > 0.

Signed-off-by: Zorro Lang <zlang@kernel.org>
---

V2 replace "fiemap" with "stat" command, to check if a file has extents.
That helps this case more common.

Thanks,
Zorro

 tests/generic/999     | 42 ++++++++++++++++++++++++++++++++++++++++++
 tests/generic/999.out |  5 +++++
 2 files changed, 47 insertions(+)
 create mode 100755 tests/generic/999
 create mode 100644 tests/generic/999.out

diff --git a/tests/generic/999 b/tests/generic/999
new file mode 100755
index 00000000..8b4596e0
--- /dev/null
+++ b/tests/generic/999
@@ -0,0 +1,42 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2022 Red Hat, Inc.  All Rights Reserved.
+#
+# FS QA Test No. 999
+#
+# Test an issue in the truncate codepath where on-disk inode sizes are logged
+# prematurely via the free eofblocks path on file close.
+#
+. ./common/preamble
+_begin_fstest auto quick shutdown
+
+# real QA test starts here
+_supported_fs xfs
+_require_scratch
+_require_scratch_shutdown
+_scratch_mkfs > $seqres.full 2>&1
+_scratch_mount
+
+echo "Create many small files with one extent at least"
+for ((i=0; i<10000; i++));do
+	$XFS_IO_PROG -f -c "pwrite 0 4k" $SCRATCH_MNT/file.$i >/dev/null 2>&1
+done
+
+echo "Shutdown the fs suddently"
+_scratch_shutdown
+
+echo "Cycle mount"
+_scratch_cycle_mount
+
+echo "Check file's (di_size > 0) extents"
+for f in $(find $SCRATCH_MNT -type f -size +0);do
+	# Check if the file has any extent
+	if [ "$(stat -c "%b" $f)" = "0" ];then
+		echo " - $f get no extents, but its di_size > 0"
+		break
+	fi
+done
+
+# success, all done
+status=0
+exit
diff --git a/tests/generic/999.out b/tests/generic/999.out
new file mode 100644
index 00000000..50008783
--- /dev/null
+++ b/tests/generic/999.out
@@ -0,0 +1,5 @@
+QA output created by 999
+Create many small files with one extent at least
+Shutdown the fs suddently
+Cycle mount
+Check file's (di_size > 0) extents
-- 
2.31.1