[PATCH v5 04/10] fstests: verify fanotify isolation on cloned filesystems

Verify that fanotify events are correctly routed to the appropriate
watcher when cloned filesystems are mounted.
Helps verify kernel's event notification distinguishes between devices
sharing the same FSID/UUID.

Signed-off-by: Anand Jain <[email protected]>
---
 common/config         |   1 +
 tests/generic/801     | 125 ++++++++++++++++++++++++++++++++++++++++++
 tests/generic/801.out |   7 +++
 3 files changed, 133 insertions(+)
 create mode 100644 tests/generic/801
 create mode 100644 tests/generic/801.out

diff --git a/common/config b/common/config
index 605a57947a40..1588bdcb1aa1 100644
--- a/common/config
+++ b/common/config
@@ -243,6 +243,7 @@ export PARTED_PROG="$(type -P parted)"
 export XFS_PROPERTY_PROG="$(type -P xfs_property)"
 export FSCRYPTCTL_PROG="$(type -P fscryptctl)"
 export INOTIFYWAIT_PROG="$(type -P inotifywait)"
+export FSNOTIFYWAIT_PROG="$(type -P fsnotifywait)"
 
 # udev wait functions.
 #
diff --git a/tests/generic/801 b/tests/generic/801
new file mode 100644
index 000000000000..5cbdfb85539b
--- /dev/null
+++ b/tests/generic/801
@@ -0,0 +1,125 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2026 Anand Jain <[email protected]>.  All Rights Reserved.
+#
+# FS QA Test 801
+# Verify fanotify FID functionality on cloned filesystems by setting up
+# watchers and making sure notifications are in the correct logs files.
+
+. ./common/preamble
+
+_begin_fstest auto quick mount clone
+
+_require_test
+_require_block_device $TEST_DEV
+_require_loop
+_require_command "$FSNOTIFYWAIT_PROG" fsnotifywait
+
+_cleanup()
+{
+	cd /
+	[[ -n $pid1 ]] && { kill -TERM "$pid1" 2> /dev/null; wait $pid1; }
+	[[ -n $pid2 ]] && { kill -TERM "$pid2" 2> /dev/null; wait $pid2; }
+
+	if [ "$semanage_added" = "yes" ]; then
+		semanage permissive -d unconfined_t >/dev/null 2>&1 || true
+	fi
+
+	umount $mnt1 $mnt2 2>/dev/null
+	_loop_image_destroy "${devs[@]}" 2> /dev/null
+	rm -r -f $tmp.*
+}
+
+monitor_fanotify()
+{
+	local mmnt=$1
+	exec stdbuf -oL $FSNOTIFYWAIT_PROG -m -F -S -e create "$mmnt" 2>&1
+}
+
+fsid_to_fid_parts()
+{
+	local fsid=$1
+	# Pad to 16 hex chars (64-bit), then split into two 32-bit halves
+	local padded=$(printf '%016x' "0x${fsid}")
+	local hi=$(printf '%x' "0x${padded:0:8}")   # strips leading zeros
+	local lo=$(printf '%x' "0x${padded:8:8}")   # strips leading zeros
+	echo "${hi}.${lo}"
+}
+
+devs=()
+_loop_image_create_clone devs
+mkdir -p $TEST_DIR/$seq
+mnt1=$TEST_DIR/$seq/mnt1
+mnt2=$TEST_DIR/$seq/mnt2
+mkdir -p $mnt1
+mkdir -p $mnt2
+
+_mount $(_common_dev_mount_options) $(_clone_mount_option) ${devs[0]} $mnt1 || \
+						_fail "Failed to mount dev1"
+_mount $(_common_dev_mount_options) $(_clone_mount_option) ${devs[1]} $mnt2 || \
+						_fail "Failed to mount dev2"
+
+fsid1=$(stat -f -c "%i" $mnt1)
+fsid2=$(stat -f -c "%i" $mnt2)
+
+[[ "$fsid1" == "$fsid2" ]] && \
+	_notrun "Require clone filesystem with unique f_fsid"
+
+log1=$tmp.fanotify1
+log2=$tmp.fanotify2
+
+pid1=""
+pid2=""
+echo "Setup FID fanotify watchers on both mnt1 and mnt2"
+semanage_added="no"
+if [ "$(getenforce 2>/dev/null)" = "Enforcing" ]; then
+    if ! semanage permissive -l | grep -q "unconfined_t"; then
+        semanage permissive -a unconfined_t >/dev/null 2>&1 && semanage_added="yes"
+    fi
+fi
+
+( monitor_fanotify "$mnt1" > "$log1" ) &
+pid1=$!
+( monitor_fanotify "$mnt2" > "$log2" ) &
+pid2=$!
+sleep 2
+
+echo "Trigger file creation on mnt1"
+touch $mnt1/file_on_mnt1
+sync
+sleep 1
+
+echo "Trigger file creation on mnt2"
+touch $mnt2/file_on_mnt2
+sync
+sleep 1
+
+echo "Verify fsid in the fanotify"
+kill $pid1 $pid2
+wait $pid1 $pid2 2>/dev/null
+pid1=""
+pid2=""
+
+e_fsid1=$(fsid_to_fid_parts "$fsid1")
+e_fsid2=$(fsid_to_fid_parts "$fsid2")
+
+echo $fsid1 $e_fsid1 $fsid2 $e_fsid2 >> $seqres.full
+cat $log1 >> $seqres.full
+cat $log2 >> $seqres.full
+
+if grep -qF "$e_fsid1" "$log1" && ! grep -qF "$e_fsid2" "$log1"; then
+	echo "SUCCESS: mnt1 events found"
+else
+	[ ! -s "$log1" ] && echo "  - mnt1 received no events."
+	grep -qF "$e_fsid2" "$log1" && echo "  - mnt1 received event from mnt2."
+fi
+
+if grep -qF "$e_fsid2" "$log2" && ! grep -qF "$e_fsid1" "$log2"; then
+	echo "SUCCESS: mnt2 events found"
+else
+	[ ! -s "$log2" ] && echo "  - mnt2 received no events."
+	grep -qF "$e_fsid1" "$log2" && echo "  - mnt2 received event from mnt1."
+fi
+
+status=0
+exit
diff --git a/tests/generic/801.out b/tests/generic/801.out
new file mode 100644
index 000000000000..d7b318d9f27c
--- /dev/null
+++ b/tests/generic/801.out
@@ -0,0 +1,7 @@
+QA output created by 801
+Setup FID fanotify watchers on both mnt1 and mnt2
+Trigger file creation on mnt1
+Trigger file creation on mnt2
+Verify fsid in the fanotify
+SUCCESS: mnt1 events found
+SUCCESS: mnt2 events found
-- 
2.43.0