On 29/5/26 12:36, Darrick J. Wong wrote:
On Thu, May 28, 2026 at 12:05:36PM +0800, Anand Jain wrote:
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]>
---
tests/generic/801 | 135 ++++++++++++++++++++++++++++++++++++++++++
tests/generic/801.out | 7 +++
2 files changed, 142 insertions(+)
create mode 100644 tests/generic/801
create mode 100644 tests/generic/801.out
diff --git a/tests/generic/801 b/tests/generic/801
new file mode 100644
index 000000000000..3bfb87d41922
--- /dev/null
+++ b/tests/generic/801
@@ -0,0 +1,135 @@
+#! /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
+_require_unique_f_fsid
+
+_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.*
+}
+
+# Run fsnotifywait in unbuffered mode to watch filesystem-wide create events
+monitor_fanotify()
+{
+ local mmnt=$1
+ exec stdbuf -oL $FSNOTIFYWAIT_PROG -m -F -S -e create "$mmnt" 2>&1
I guess you need stdbuf to force fsnotifywait to run in linebuffered
mode even if you pipe/redirect it somewhere?
yeah, stdbuf helps get the output as and when created.
+}
+
+# Transform f_fsid into the hi.lo format used in fanotify FID logs
+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}"
+}
+
+# Create base loop device and its clone
+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 both base and clone filesystems using required clone mount options
+_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]} $mnt2 ||
\
+ _fail "Failed to mount dev2"
+
+# Fetch filesystem IDs to verify the kernel can differentiate between them
+fsid1=$(stat -f -c "%i" $mnt1)
+fsid2=$(stat -f -c "%i" $mnt2)
+
+log1=$tmp.fanotify1
+log2=$tmp.fanotify2
+
+pid1=""
+pid2=""
+echo "Setup FID fanotify watchers on both mnt1 and mnt2"
+
+# Permit unconfined_t domains when SELinux is enforcing to prevent fanotify
+# blockages
+semanage_added="no"
+if [ "$(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
Is there a cleaner way to manage setting up and automatically undoing
this step?
There might not be, since iirc the suggestion to register cleanup
functions in a cleanups=() array and call them all in reverse order
didn't go anywhere.
If there are multiple use cases, we could wrap it up in a helper,
similar to _scratch_dev_pool_{get|put}, if it helps.
Thanks, Anand
+
+# Start asynchronous fanotify monitors
+( 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")
+
+# Dump debug details to the full log
+echo $fsid1 $e_fsid1 $fsid2 $e_fsid2 >> $seqres.full
+cat $log1 >> $seqres.full
+cat $log2 >> $seqres.full
+
+# Ensure monitor 1 only captured events belonging to mnt 1 and fsid 1
+if grep -qF "$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
+
+# Ensure monitor 2 only captured events belonging to mnt 2 and fsid 2
+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
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