[PATCH] 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>
---

Hi,

There was an very old xfs bug on rhel-6.5, I'd like to share its reproducer to
fstests. I've tried generic/044~049, no one can reproduce this bug, so I
have to write this new one. It fails on rhel-6.5 [1], and test passed on
later kernel.

I hard to say which patch fix this issue exactly, it's fixed by a patchset
which does code improvement/cleanup.

Thanks,
Zorro

[1]
# ./check generic/999
FSTYP         -- xfs (non-debug)
PLATFORM      -- Linux/x86_64
MKFS_OPTIONS  -- -f -bsize=4096 /dev/loop1
MOUNT_OPTIONS -- -o context=system_u:object_r:nfs_t:s0 /dev/loop1 /mnt/scratch

generic/999 2s ... - output mismatch (see /root/xfstests-dev/results//generic/999.out.bad)
    --- tests/generic/999.out   2022-11-04 00:54:11.123353054 -0400
    +++ /root/xfstests-dev/results//generic/999.out.bad 2022-11-04 04:24:57.861673433 -0400
    @@ -1 +1,3 @@
     QA output created by 999
    + - /mnt/scratch/1 get no extents, but its di_size > 0
    +/mnt/scratch/1:
    ...
    (Run 'diff -u tests/generic/045.out /root/xfstests-dev/results//generic/999.out.bad'  to see the entire diff)
Ran: generic/999
Failures: generic/999
Failed 1 of 1 tests

 tests/generic/999     | 46 +++++++++++++++++++++++++++++++++++++++++++
 tests/generic/999.out |  5 +++++
 2 files changed, 51 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..a2e662fc
--- /dev/null
+++ b/tests/generic/999
@@ -0,0 +1,46 @@
+#! /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_xfs_io_command fiemap
+_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
+	$XFS_IO_PROG -c "fiemap" $f > $tmp.fiemap
+	# Check if the file has any extent
+	grep -Eq '^[[:space:]]+[0-9]+:' $tmp.fiemap
+	if [ $? -ne 0 ];then
+		echo " - $f get no extents, but its di_size > 0"
+		cat $tmp.fiemap
+		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