xfs: test xfs_healer wont repair the wrong filesystem

Make sure that when xfs_healer needs to reopen a filesystem to repair it, it
won't latch on to another xfs filesystem that has been mounted atop the same
mountpoint.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>

diff --git a/tests/xfs/664 b/tests/xfs/664
new file mode 100755 (executable)
index 0000000..4d746fb
--- /dev/null
+++ b/tests/xfs/664
@@ -0,0 +1,135 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2025-2026 Oracle.  All Rights Reserved.
+#
+# FS QA Test No. 664
+#
+# Ensure that autonomous self healing won't fix the wrong filesystem if a
+# snapshot of the original filesystem is now mounted on the same directory as
+# the original.
+#
+. ./common/preamble
+_begin_fstest auto selfhealing
+
+. ./common/filter
+. ./common/fuzzy
+. ./common/systemd
+
+_cleanup()
+{
+       command -v _kill_fsstress &>/dev/null && _kill_fsstress
+       cd /
+       rm -r -f $tmp.*
+       test -e "$mntpt" && _unmount "$mntpt" &>/dev/null
+       test -e "$mntpt" && _unmount "$mntpt" &>/dev/null
+       test -e "$loop1" && _destroy_loop_device "$loop1"
+       test -e "$loop2" && _destroy_loop_device "$loop2"
+       test -e "$testdir" && rm -r -f "$testdir"
+}
+
+_require_test
+_require_scrub
+_require_xfs_io_command "repair"       # online repair support
+_require_xfs_db_command "blocktrash"
+_require_command "$XFS_HEALER_PROG" "xfs_healer"
+_require_command "$XFS_PROPERTY_PROG" "xfs_property"
+
+testdir=$TEST_DIR/$seq
+mntpt=$testdir/mount
+disk1=$testdir/disk1
+disk2=$testdir/disk2
+
+mkdir -p "$mntpt"
+$XFS_IO_PROG -f -c "truncate 300m" $disk1
+$XFS_IO_PROG -f -c "truncate 300m" $disk2
+loop1="$(_create_loop_device "$disk1")"
+
+filter_mntpt() {
+       sed -e "s|$mntpt|MNTPT|g"
+}
+
+_mkfs_dev "$loop1" >> $seqres.full
+_mount "$loop1" "$mntpt" || _notrun "cannot mount victim filesystem"
+
+_xfs_has_feature $mntpt rmapbt || \
+       _notrun "reverse mapping required to test directory auto-repair"
+_xfs_has_feature $mntpt parent || \
+       _notrun "parent pointers required to test directory auto-repair"
+_require_xfs_healer $mntpt --repair
+
+# Configure the filesystem for automatic repair of the filesystem.
+$XFS_PROPERTY_PROG $mntpt set autofsck=repair >> $seqres.full
+
+# Create a largeish directory
+dblksz=$(_xfs_get_dir_blocksize "$mntpt")
+echo testdata > $mntpt/a
+mkdir -p "$mntpt/some/victimdir"
+for ((i = 0; i < (dblksz / 255); i++)); do
+       fname="$(printf "%0255d" "$i")"
+       ln $mntpt/a $mntpt/some/victimdir/$fname
+done
+
+# Did we get at least two dir blocks?
+dirsize=$(stat -c '%s' $mntpt/some/victimdir)
+test "$dirsize" -gt "$dblksz" || echo "failed to create two-block directory"
+
+# Clone the fs, break the directory, remount filesystem
+_unmount "$mntpt"
+
+cp --sparse=always "$disk1" "$disk2" || _fail "cannot copy disk1"
+loop2="$(_create_loop_device_like_bdev "$disk2" "$loop1")"
+
+$XFS_DB_PROG "$loop1" -x \
+       -c 'path /some/victimdir' \
+       -c 'bmap' \
+       -c 'dblock 1' \
+       -c 'blocktrash -z -0 -o 0 -x 2048 -y 2048 -n 2048' >> $seqres.full
+_mount "$loop1" "$mntpt" || _fail "cannot mount broken fs"
+
+_invoke_xfs_healer "$mntpt" "$tmp.healer" --repair
+
+# Stop the healer process so that it can't read error events while we do some
+# shenanigans.
+test -n "$XFS_HEALER_PID" || _fail "nobody set XFS_HEALER_PID?"
+kill -STOP $XFS_HEALER_PID
+
+echo "LOG $XFS_HEALER_PID SO FAR:" >> $seqres.full
+cat $tmp.healer >> $seqres.full
+
+# Access the broken directory to trigger a repair event, which will not yet be
+# processed.
+ls $mntpt/some/victimdir > /dev/null 2> $tmp.err
+filter_mntpt < $tmp.err
+
+ps auxfww | grep xfs_healer >> $seqres.full
+
+echo "LOG AFTER TRYING TO POKE:" >> $seqres.full
+cat $tmp.healer >> $seqres.full
+
+# Mount the clone filesystem to the same mountpoint so that the healer cannot
+# actually reopen it to perform repairs.
+_mount "$loop2" "$mntpt" -o nouuid || _fail "cannot mount decoy fs"
+
+grep -w xfs /proc/mounts >> $seqres.full
+
+# Continue the healer process so it can handle events now.  Wait a few seconds
+# while it fails to reopen disk1's mount point to repair things.
+kill -CONT $XFS_HEALER_PID
+sleep 2
+
+new_dir_unmount() {
+       _unmount "$mntpt"
+       _unmount "$mntpt"
+}
+
+# Unmount to kill the healer
+_kill_xfs_healer new_dir_unmount
+echo "LOG AFTER FAILURE" >> $seqres.full
+cat $tmp.healer >> $seqres.full
+
+# Did the healer log complaints about not being able to reopen the mountpoint
+# to enact repairs?
+grep -q 'Stale file handle' $tmp.healer || \
+       echo "Should have seen stale file handle complaints"
+
+_exit 0

diff --git a/tests/xfs/664.out b/tests/xfs/664.out
new file mode 100755 (executable)
index 0000000..5cbf251
--- /dev/null
+++ b/tests/xfs/664.out
@@ -0,0 +1,2 @@
+QA output created by 664
+ls: reading directory 'MNTPT/some/victimdir': Structure needs cleaning