overlay: another test for dropping nlink below zero

This is a variant on test overlay/034.

This variant is mangling upper hardlinks instead of lower hardlinks
and does not require the inodes index feature.

This is a regression test for kernel commit 83552eacdfc0
("ovl: fix WARN_ON nlink drop to zero")

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

diff --git a/tests/overlay/072 b/tests/overlay/072
new file mode 100755 (executable)
index 0000000..d2cb93b
--- /dev/null
+++ b/tests/overlay/072
@@ -0,0 +1,85 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2020 CTERA Networks. All Rights Reserved.
+#
+# FS QA Test 072
+#
+# Test overlay nlink when adding upper hardlinks.
+#
+# nlink of overlay inode could be dropped indefinitely by adding
+# unaccounted upper hardlinks underneath a mounted overlay and
+# trying to remove them.
+#
+# This is a variant of test overlay/034 with mangling of upper instead
+# of lower hardlinks. Unlike overlay/034, this test does not require the
+# inode index feature and will pass whether is it enabled or disabled
+# by default.
+#
+# This is a regression test for kernel commit 83552eacdfc0
+# ("ovl: fix WARN_ON nlink drop to zero").
+# Without the fix, the test triggers
+# WARN_ON(inode->i_nlink == 0) in drop_link().
+#
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+tmp=/tmp/$$
+status=1       # failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+       cd /
+       rm -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+# real QA test starts here
+_supported_fs overlay
+_supported_os Linux
+_require_scratch
+
+upperdir=$OVL_BASE_SCRATCH_MNT/$OVL_UPPER
+
+# Remove all files from previous tests
+_scratch_mkfs
+
+# Create upper hardlink
+mkdir -p $upperdir
+touch $upperdir/0
+ln $upperdir/0 $upperdir/1
+
+_scratch_mount
+
+# Verify overlay inode nlink 2 same as upper inode
+stat -c '%h' $SCRATCH_MNT/0
+
+# Add upper hardlinks while overlay is mounted - overlay inode nlink
+# is not being updated
+ln $upperdir/0 $upperdir/2
+ln $upperdir/0 $upperdir/3
+
+# Unlink the 2 un-accounted upper hardlinks - overlay inode nlinks
+# drops 2 and may reach 0 if the situation is not detected
+rm $SCRATCH_MNT/2
+rm $SCRATCH_MNT/3
+
+# Check if getting ENOENT when trying to link !I_LINKABLE with nlink 0
+ln $SCRATCH_MNT/0 $SCRATCH_MNT/4
+
+# Unlink all hardlinks - if overlay inode nlink is 0, this will trigger
+# WARN_ON() in drop_nlink()
+rm $SCRATCH_MNT/0
+rm $SCRATCH_MNT/1
+rm $SCRATCH_MNT/4
+
+echo "Silence is golden"
+status=0
+exit

diff --git a/tests/overlay/072.out b/tests/overlay/072.out
new file mode 100644 (file)
index 0000000..28eeb94
--- /dev/null
+++ b/tests/overlay/072.out
@@ -0,0 +1,3 @@
+QA output created by 072
+2
+Silence is golden

diff --git a/tests/overlay/group b/tests/overlay/group
index 43ad8a52cfccd86acd0dc0b2cf92382102694062..82876d0979133916b70c9ca9315cee6eb51cffdf 100644 (file)
--- a/tests/overlay/group
+++ b/tests/overlay/group
@@ -74,3 +74,4 @@
 069 auto quick copyup hardlink exportfs nested nonsamefs
 070 auto quick copyup redirect nested
 071 auto quick copyup redirect nested nonsamefs
 069 auto quick copyup hardlink exportfs nested nonsamefs
 070 auto quick copyup redirect nested
 071 auto quick copyup redirect nested nonsamefs

+072 auto quick copyup hardlink