[PATCH v3 0/9] fstests: add test coverage for cloned filesystem ids

[PATCH v3 0/9] fstests: add test coverage for cloned filesystem ids

[Anand Jain]

v3:
 Dropped the -o nouuid mount option.
 Added a Btrfs test case to verify clones of filesystems using the
   metadata_uuid superblock feature.
 Updated _loop_image_create_clone() to handle necessary pre-clone
   filesystem tuning.

v2:
  https://lore.kernel.org/fstests/cover.1774090817.git.asj@kernel.org

Anand Jain (9):
  fstests: add _loop_image_create_clone() helper
  fstests: add _clone_mount_option() helper
  fstests: add test for inotify isolation on cloned devices
  fstests: verify fanotify isolation on cloned filesystems
  fstests: verify f_fsid for cloned filesystems
  fstests: verify libblkid resolution of duplicate UUIDs
  fstests: verify IMA isolation on cloned filesystems
  fstests: verify exportfs file handles on cloned filesystems
  fstests: btrfs: test UUID consistency for clones with metadata_uuid

 common/config         |   2 +
 common/rc             |  58 +++++++++++++++++++++
 tests/btrfs/348       |  91 +++++++++++++++++++++++++++++++++
 tests/btrfs/348.out   |  19 +++++++
 tests/generic/800     |  88 ++++++++++++++++++++++++++++++++
 tests/generic/800.out |   7 +++
 tests/generic/801     | 115 ++++++++++++++++++++++++++++++++++++++++++
 tests/generic/801.out |   7 +++
 tests/generic/802     |  61 ++++++++++++++++++++++
 tests/generic/802.out |   7 +++
 tests/generic/803     |  75 +++++++++++++++++++++++++++
 tests/generic/803.out |  19 +++++++
 tests/generic/804     | 102 +++++++++++++++++++++++++++++++++++++
 tests/generic/804.out |  10 ++++
 tests/generic/805     |  72 ++++++++++++++++++++++++++
 tests/generic/805.out |   2 +
 16 files changed, 735 insertions(+)
 create mode 100644 tests/btrfs/348
 create mode 100644 tests/btrfs/348.out
 create mode 100644 tests/generic/800
 create mode 100644 tests/generic/800.out
 create mode 100644 tests/generic/801
 create mode 100644 tests/generic/801.out
 create mode 100644 tests/generic/802
 create mode 100644 tests/generic/802.out
 create mode 100644 tests/generic/803
 create mode 100644 tests/generic/803.out
 create mode 100644 tests/generic/804
 create mode 100644 tests/generic/804.out
 create mode 100644 tests/generic/805
 create mode 100644 tests/generic/805.out

-- 
2.43.0

[PATCH v3 1/9] fstests: add _loop_image_create_clone() helper

[Anand Jain]

Introduce _loop_image_create_clone() and _loop_image_destroy() to mkfs an
image file and clone it to another image file, and attach a loop device to
them. And its destroy part.

Signed-off-by: Anand Jain <asj@kernel.org>
---
 common/rc | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/common/rc b/common/rc
index 9632b211b58f..0e7b7eb1d98f 100644
--- a/common/rc
+++ b/common/rc
@@ -1503,6 +1503,50 @@ _scratch_resvblks()
 	esac
 }
 
+_loop_image_create_clone()
+{
+	local -n _ret=$1
+	local pre_clone_tune_func=$2
+	local img_file=$TEST_DIR/${seq}.img
+	local img_file_clone=$TEST_DIR/${seq}_clone.img
+	local size=$(_small_fs_size_mb 128) # Smallest possible
+	local loop_devs
+
+	size=$((size * 1024 * 1024))
+	$XFS_IO_PROG -f -c "truncate $size" $img_file
+
+	loop_devs=$(_create_loop_device $img_file)
+	_ret=($loop_devs)
+
+	case $FSTYP in
+	xfs)
+		_mkfs_dev "-s size=4096" $img_file
+		;;
+	btrfs)
+		_mkfs_dev $img_file
+		;;
+	*)
+		_mkfs_dev $img_file
+		;;
+	esac
+
+	($pre_clone_tune_func)
+
+	cp $img_file $img_file_clone
+
+	loop_devs="$loop_devs $(_create_loop_device $img_file_clone)"
+
+	_ret=($loop_devs)
+}
+
+_loop_image_destroy()
+{
+	for d in "$@"; do
+		local f=$(losetup --noheadings --output BACK-FILE $d)
+		_destroy_loop_device "$d"
+		[ -n "$f" ] && rm -f "$f"
+	done
+}
 
 # Repair scratch filesystem.  Returns 0 if the FS is good to go (either no
 # errors found or errors were fixed) and nonzero otherwise; also spits out
-- 
2.43.0

[PATCH v3 2/9] fstests: add _clone_mount_option() helper

[Anand Jain]

Adds _clone_mount_option() helper function to handle filesystem-specific
requirements for mounting cloned devices. Abstract the need for -o nouuid
on XFS.

Signed-off-by: Anand Jain <asj@kernel.org>
---
 common/rc | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/common/rc b/common/rc
index 0e7b7eb1d98f..2d28e174f605 100644
--- a/common/rc
+++ b/common/rc
@@ -397,6 +397,20 @@ _scratch_mount_options()
 					$SCRATCH_DEV $SCRATCH_MNT
 }
 
+_clone_mount_option()
+{
+	local mount_opts=""
+
+	case "$FSTYP" in
+	xfs)
+		mount_opts="-o nouuid"
+		;;
+	*)
+	esac
+
+	echo $mount_opts
+}
+
 _supports_filetype()
 {
 	local dir=$1
-- 
2.43.0

[PATCH v3 3/9] fstests: add test for inotify isolation on cloned devices

[Anand Jain]

Add a new test, to verify that the kernel correctly differentiates between
two block devices sharing the same FSID/UUID.

Signed-off-by: Anand Jain <asj@kernel.org>
---
 common/config         |  1 +
 tests/generic/800     | 88 +++++++++++++++++++++++++++++++++++++++++++
 tests/generic/800.out |  7 ++++
 3 files changed, 96 insertions(+)
 create mode 100644 tests/generic/800
 create mode 100644 tests/generic/800.out

diff --git a/common/config b/common/config
index 4fd4c2c8af11..605a57947a40 100644
--- a/common/config
+++ b/common/config
@@ -242,6 +242,7 @@ export BTRFS_MAP_LOGICAL_PROG=$(type -P btrfs-map-logical)
 export PARTED_PROG="$(type -P parted)"
 export XFS_PROPERTY_PROG="$(type -P xfs_property)"
 export FSCRYPTCTL_PROG="$(type -P fscryptctl)"
+export INOTIFYWAIT_PROG="$(type -P inotifywait)"
 
 # udev wait functions.
 #
diff --git a/tests/generic/800 b/tests/generic/800
new file mode 100644
index 000000000000..16bc1159a2e1
--- /dev/null
+++ b/tests/generic/800
@@ -0,0 +1,88 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2026 Anand Jain <asj@kernel.org>.  All Rights Reserved.
+#
+# FS QA Test 800
+#
+# Verify if the kernel or userspace becomes confused when two block devices
+# share the same fid/fsid/uuid. Create inotify on both original and cloned
+# filesystem. Monitor the notification in the respective logs.
+
+. ./common/preamble
+
+_begin_fstest auto quick mount clone
+
+_require_test
+_require_loop
+_require_command "$INOTIFYWAIT_PROG" inotifywait
+
+_cleanup()
+{
+	cd /
+	[[ -n $pid1 ]] && { kill -TERM "$pid1" 2> /dev/null; wait $pid1; }
+	[[ -n $pid2 ]] && { kill -TERM "$pid2" 2> /dev/null; wait $pid2; }
+	rm -r -f $tmp.*
+	_unmount $mnt1 2>/dev/null
+	_unmount $mnt2 2>/dev/null
+	_loop_image_destroy "${devs[@]}" 2> /dev/null
+}
+
+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]} $mnt2 || \
+						_fail "Failed to mount dev2"
+
+log1=$tmp.inotify1
+log2=$tmp.inotify2
+
+pid1=""
+pid2=""
+echo "Setup inotify watchers on both mnt1 and mnt2"
+$INOTIFYWAIT_PROG -m -e create --format '%f' $mnt1 > $log1 2>&1 &
+pid1=$!
+$INOTIFYWAIT_PROG -m -e create --format '%f' $mnt2 > $log2 2>&1 &
+pid2=$!
+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 inotify isolation"
+kill $pid1 $pid2
+wait $pid1 $pid2 2>/dev/null
+pid1=""
+pid2=""
+
+if grep -q "file_on_mnt1" $log1 && ! grep -q "file_on_mnt2" $log1; then
+	echo "SUCCESS: mnt1 events isolated."
+else
+	echo "FAIL: mnt1 inotify confusion!"
+	[ ! -s $log1 ] && echo "  - mnt1 received no events."
+	grep -q "file_on_mnt2" $log1 && echo "  - mnt1 received event from mnt2."
+fi
+
+if grep -q "file_on_mnt2" $log2 && ! grep -q "file_on_mnt1" $log2; then
+	echo "SUCCESS: mnt2 events isolated."
+else
+	echo "FAIL: mnt2 inotify confusion!"
+	[ ! -s $log2 ] && echo "  - mnt2 received no events."
+	grep -q "file_on_mnt1" $log2 && echo "  - mnt2 received event from mnt1."
+fi
+
+status=0
+exit
diff --git a/tests/generic/800.out b/tests/generic/800.out
new file mode 100644
index 000000000000..b10842a31210
--- /dev/null
+++ b/tests/generic/800.out
@@ -0,0 +1,7 @@
+QA output created by 800
+Setup inotify watchers on both mnt1 and mnt2
+Trigger file creation on mnt1
+Trigger file creation on mnt2
+Verify inotify isolation
+SUCCESS: mnt1 events isolated.
+SUCCESS: mnt2 events isolated.
-- 
2.43.0

[PATCH v3 4/9] fstests: verify fanotify isolation on cloned filesystems

[Anand Jain]

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 <asj@kernel.org>
---
 common/config         |   1 +
 tests/generic/801     | 115 ++++++++++++++++++++++++++++++++++++++++++
 tests/generic/801.out |   7 +++
 3 files changed, 123 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..3f64e4de2206
--- /dev/null
+++ b/tests/generic/801
@@ -0,0 +1,115 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2026 Anand Jain <asj@kernel.org>.  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_loop
+_require_command "$FSNOTIFYWAIT_PROG" fsnotifywait
+
+[ "$FSTYP" = "ext4" ] && _fixed_by_kernel_commit xxxxxxxxxxxx \
+	"ext4: derive f_fsid from block device to avoid collisions"
+
+_cleanup()
+{
+	cd /
+	[[ -n $pid1 ]] && { kill -TERM "$pid1" 2> /dev/null; wait $pid1; }
+	[[ -n $pid2 ]] && { kill -TERM "$pid2" 2> /dev/null; wait $pid2; }
+	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=$tmp.fanotify2
+
+pid1=""
+pid2=""
+echo "Setup FID fanotify watchers on both mnt1 and mnt2"
+( monitor_fanotify "$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

[PATCH v3 5/9] fstests: verify f_fsid for cloned filesystems

[Anand Jain]

Verify that the cloned filesystem provides an f_fsid that is persistent
across mount cycles, yet unique from the original filesystem's f_fsid.

Signed-off-by: Anand Jain <asj@kernel.org>
---
 tests/generic/802     | 61 +++++++++++++++++++++++++++++++++++++++++++
 tests/generic/802.out |  7 +++++
 2 files changed, 68 insertions(+)
 create mode 100644 tests/generic/802
 create mode 100644 tests/generic/802.out

diff --git a/tests/generic/802 b/tests/generic/802
new file mode 100644
index 000000000000..83e75dcd0d78
--- /dev/null
+++ b/tests/generic/802
@@ -0,0 +1,61 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2026 Anand Jain <asj@kernel.org>.  All Rights Reserved.
+#
+# FS QA Test 802
+# Verify f_fsid and s_uuid of cloned filesystems across mount cycle.
+
+. ./common/preamble
+
+_begin_fstest auto quick mount clone
+
+_require_test
+_require_loop
+
+[ "$FSTYP" = "btrfs" ] && _fixed_by_kernel_commit xxxxxxxxxxxx \
+	"btrfs: use on-disk uuid for s_uuid in temp_fsid mounts"
+[ "$FSTYP" = "btrfs" ] && _fixed_by_kernel_commit xxxxxxxxxxxx \
+	"btrfs: derive f_fsid from on-disk fsuuid and dev_t"
+
+_cleanup()
+{
+	cd /
+	rm -r -f $tmp.*
+	umount $mnt1 $mnt2 2>/dev/null
+	_loop_image_destroy "${devs[@]}" 2> /dev/null
+}
+
+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]} $mnt2 || \
+						_fail "Failed to mount dev2"
+
+fsid_scratch=$(stat -f -c "%i" $mnt1)
+fsid_clone=$(stat -f -c "%i" $mnt2)
+
+echo "**** fsid initially ****"
+echo $fsid_scratch | sed -e "s/$fsid_scratch/FSID_SCRATCH/g"
+echo $fsid_clone | sed -e "s/$fsid_clone/FSID_CLONE/g"
+
+# Make sure fsid still match across a mount cycle, also reverse the order.
+echo "**** fsid after mount cycle ****"
+_unmount $mnt1
+_unmount $mnt2
+_mount $(_common_dev_mount_options) $(_clone_mount_option) ${devs[1]} $mnt2 || \
+						_fail "Failed to mount dev2"
+_mount $(_common_dev_mount_options) $(_clone_mount_option) ${devs[0]} $mnt1 || \
+						_fail "Failed to mount dev1"
+
+stat -f -c "%i" $mnt1 | sed -e "s/$fsid_scratch/FSID_SCRATCH/g"
+stat -f -c "%i" $mnt2 | sed -e "s/$fsid_clone/FSID_CLONE/g"
+
+status=0
+exit
diff --git a/tests/generic/802.out b/tests/generic/802.out
new file mode 100644
index 000000000000..d1e008f122bb
--- /dev/null
+++ b/tests/generic/802.out
@@ -0,0 +1,7 @@
+QA output created by 802
+**** fsid initially ****
+FSID_SCRATCH
+FSID_CLONE
+**** fsid after mount cycle ****
+FSID_SCRATCH
+FSID_CLONE
-- 
2.43.0

[PATCH v3 6/9] fstests: verify libblkid resolution of duplicate UUIDs

[Anand Jain]

Verify how findmnt, df (libblkid) resolve device paths when multiple
block devices share the same FSUUID.

Signed-off-by: Anand Jain <asj@kernel.org>
---
 tests/generic/803     | 75 +++++++++++++++++++++++++++++++++++++++++++
 tests/generic/803.out | 19 +++++++++++
 2 files changed, 94 insertions(+)
 create mode 100644 tests/generic/803
 create mode 100644 tests/generic/803.out

diff --git a/tests/generic/803 b/tests/generic/803
new file mode 100644
index 000000000000..1e0fbc768050
--- /dev/null
+++ b/tests/generic/803
@@ -0,0 +1,75 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2026 Anand Jain <asj@kernel.org>.  All Rights Reserved.
+#
+# FS QA Test 803
+# Verify how libblkid resolve devices when multiple devices sharing the
+# same FSUUID.
+
+. ./common/preamble
+. ./common/filter
+
+_begin_fstest auto quick mount clone
+
+_require_test
+_require_loop
+
+_cleanup()
+{
+	cd /
+	rm -r -f $tmp.*
+	umount $mnt1 $mnt2 2>/dev/null
+	_loop_image_destroy "${devs[@]}" 2> /dev/null
+}
+
+filter_pool()
+{
+	sed -e "s|${devs[0]}|DEV1|g" -e "s|${mnt1}|MNT1|g" \
+	    -e "s|${devs[1]}|DEV2|g" -e "s|${mnt2}|MNT2|g" | _filter_spaces
+}
+
+print_info()
+{
+	local mntpt=$1
+	local tgt=$(findmnt -no SOURCE $mntpt)
+	local fsuuid=$(blkid -s UUID -o value $tgt)
+
+	echo "mntpt=$mntpt tgt=$tgt fsuuid=$fsuuid" >> $seqres.full
+	echo
+	findmnt -o SOURCE,TARGET,UUID "$tgt" | tail -n +2 | \
+				sed -e "s/${fsuuid}/FSUUID/g" | filter_pool
+	awk -v dev="$tgt" '$1 == dev { print $1, $2 }' /proc/self/mounts | \
+								filter_pool
+	df --all --output=source,target "$tgt" | tail -n +2 | filter_pool
+}
+
+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"
+
+print_info $mnt1
+print_info $mnt2
+
+echo
+echo "**** mount cycle ****"
+_unmount $mnt1
+_unmount $mnt2
+_mount $(_common_dev_mount_options) $(_clone_mount_option) ${devs[1]} $mnt2 || \
+						_fail "Failed to mount dev2"
+_mount $(_common_dev_mount_options) $(_clone_mount_option) ${devs[0]} $mnt1 || \
+						_fail "Failed to mount dev1"
+
+print_info $mnt1
+print_info $mnt2
+
+status=0
+exit
diff --git a/tests/generic/803.out b/tests/generic/803.out
new file mode 100644
index 000000000000..20a1cb36a213
--- /dev/null
+++ b/tests/generic/803.out
@@ -0,0 +1,19 @@
+QA output created by 803
+
+DEV1 MNT1 FSUUID
+DEV1 MNT1
+DEV1 MNT1
+
+DEV2 MNT2 FSUUID
+DEV2 MNT2
+DEV2 MNT2
+
+**** mount cycle ****
+
+DEV1 MNT1 FSUUID
+DEV1 MNT1
+DEV1 MNT1
+
+DEV2 MNT2 FSUUID
+DEV2 MNT2
+DEV2 MNT2
-- 
2.43.0

[PATCH v3 7/9] fstests: verify IMA isolation on cloned filesystems

[Anand Jain]

Add testcase to verify IMA measurement isolation when multiple devices
share the same FSUUID.

Signed-off-by: Anand Jain <asj@kernel.org>
---
 tests/generic/804     | 102 ++++++++++++++++++++++++++++++++++++++++++
 tests/generic/804.out |  10 +++++
 2 files changed, 112 insertions(+)
 create mode 100644 tests/generic/804
 create mode 100644 tests/generic/804.out

diff --git a/tests/generic/804 b/tests/generic/804
new file mode 100644
index 000000000000..5f5c04f97579
--- /dev/null
+++ b/tests/generic/804
@@ -0,0 +1,102 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2026 Anand Jain <asj@kernel.org>.  All Rights Reserved.
+#
+# FS QA Test 804
+# Verify IMA isolation on cloned filesystems:
+# . Mount two devices sharing the same FSUUID (cloned).
+# . Apply an IMA policy to measure files based on that FSUUID.
+# . Create unique files on each mount point to trigger measurements.
+# . Confirm the IMA log correctly attributes events to the respective mounts.
+
+. ./common/preamble
+. ./common/filter
+
+_begin_fstest auto quick clone
+
+_require_test
+_require_loop
+
+[ "$FSTYP" = "btrfs" ] && _fixed_by_kernel_commit xxxxxxxxxxxx \
+	"btrfs: use on-disk uuid for s_uuid in temp_fsid mounts"
+[ "$FSTYP" = "btrfs" ] && _fixed_by_kernel_commit xxxxxxxxxxxx \
+	"btrfs: derive f_fsid from on-disk fsuuid and dev_t"
+
+_cleanup()
+{
+	cd /
+	rm -r -f $tmp.*
+	_unmount $mnt1 2>/dev/null
+	_unmount $mnt2 2>/dev/null
+	_loop_image_destroy "${devs[@]}" 2> /dev/null
+}
+
+filter_pool()
+{
+	sed -e "s|${devs[0]}|DEV1|g" -e "s|$mnt1|MNT1|g" \
+	    -e "s|${devs[1]}|DEV2|g" -e "s|$mnt2|MNT2|g" | _filter_spaces
+}
+
+do_ima()
+{
+	local ima_policy="/sys/kernel/security/ima/policy"
+	local ima_log="/sys/kernel/security/ima/ascii_runtime_measurements"
+	local fsuuid
+	local mnt=$1
+	local enable=$2
+
+	# Since the in-memory IMA audit log is only cleared upon reboot,
+	# use unique random filenames to avoid log collisions.
+	local foofile=$(mktemp --dry-run foobar_XXXXX)
+
+	echo $mnt $enable | filter_pool
+
+	[ -w "$ima_policy" ] || _notrun "IMA policy not writable"
+
+	fsuuid=$(blkid -s UUID -o value ${devs[0]})
+
+	# Load IMA policy to measure file access specifically for this
+	# filesystem UUID.
+	if [[ $enable -eq 1 ]]; then
+		echo "measure func=FILE_CHECK fsuuid=$fsuuid" > "$ima_policy" || \
+			_notrun "Policy rejected"
+	fi
+
+	# Create a file to trigger measurement and verify its entry in
+	# the IMA log.
+	echo "test_data" > $mnt/$foofile
+
+	# For $ima_log column entry please ref to
+	grep $foofile "$ima_log" | awk '{ print $5 }' | filter_pool | \
+						sed "s/$foofile/FOOBAR_FILE/"
+
+	echo "dbg: $mnt $fsuuid $foofile" >> $seqres.full
+	cat $ima_log | tail -1 >> $seqres.full
+	echo >> $seqres.full
+}
+
+devs=()
+_loop_image_create_clone devs
+mnt1=$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"
+
+do_ima $mnt1 1
+do_ima $mnt2 0
+
+# Btrfs uses in-memory dynamic temp_fsid
+echo mount cycle
+_unmount $mnt2
+_mount $mount_opts ${devs[1]} $mnt2 || _fail "Failed to mount dev2"
+
+do_ima $mnt1 0
+do_ima $mnt2 0
+
+status=0
+exit
diff --git a/tests/generic/804.out b/tests/generic/804.out
new file mode 100644
index 000000000000..9804181d6c17
--- /dev/null
+++ b/tests/generic/804.out
@@ -0,0 +1,10 @@
+QA output created by 804
+MNT1 1
+MNT1/FOOBAR_FILE
+MNT2 0
+MNT2/FOOBAR_FILE
+mount cycle
+MNT1 0
+MNT1/FOOBAR_FILE
+MNT2 0
+MNT2/FOOBAR_FILE
-- 
2.43.0

[PATCH v3 8/9] fstests: verify exportfs file handles on cloned filesystems

[Anand Jain]

Ensure that exportfs can correctly decode file handles on a cloned
filesystem across a mount cycle, by file handles generated on a
cloned device remain valid after mount cycle.

Signed-off-by: Anand Jain <asj@kernel.org>
---
 tests/generic/805     | 72 +++++++++++++++++++++++++++++++++++++++++++
 tests/generic/805.out |  2 ++
 2 files changed, 74 insertions(+)
 create mode 100644 tests/generic/805
 create mode 100644 tests/generic/805.out

diff --git a/tests/generic/805 b/tests/generic/805
new file mode 100644
index 000000000000..18c92205304c
--- /dev/null
+++ b/tests/generic/805
@@ -0,0 +1,72 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2026 Anand Jain <asj@kernel.org>.  All Rights Reserved.
+#
+# FS QA Test No. 805
+
+. ./common/preamble
+
+_begin_fstest auto quick exportfs clone
+
+_require_test
+_require_exportfs
+_require_loop
+_require_test_program "open_by_handle"
+
+_cleanup()
+{
+	cd /
+	rm -r -f $tmp.*
+	_unmount $mnt1 2>/dev/null
+	_unmount $mnt2 2>/dev/null
+	_loop_image_destroy "${devs[@]}" 2> /dev/null
+}
+
+# Create test dir and test files, encode file handles and store to tmp file
+create_test_files()
+{
+	rm -rf $testdir
+	mkdir -p $testdir
+	$here/src/open_by_handle -cwp -o $tmp.handles_file $testdir $NUMFILES
+}
+
+# Decode file handles loaded from tmp file
+test_file_handles()
+{
+	local opt=$1
+	local when=$2
+
+	echo test_file_handles after $when
+	$here/src/open_by_handle $opt -i $tmp.handles_file $mnt2 $NUMFILES
+}
+
+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]} $mnt2 || \
+						_fail "Failed to mount dev2"
+
+NUMFILES=1
+testdir=$mnt2/testdir
+
+# Decode file handles of files/dir after cycle mount
+create_test_files
+
+_unmount $mnt1
+_unmount $mnt2
+_mount $(_common_dev_mount_options) $(_clone_mount_option) ${devs[1]} $mnt2 || \
+						_fail "Failed to mount dev2"
+_mount $(_common_dev_mount_options) $(_clone_mount_option) ${devs[0]} $mnt1 || \
+						_fail "Failed to mount dev1"
+
+test_file_handles -rp "cycle mount"
+
+status=0
+exit
diff --git a/tests/generic/805.out b/tests/generic/805.out
new file mode 100644
index 000000000000..29b11ec77ffb
--- /dev/null
+++ b/tests/generic/805.out
@@ -0,0 +1,2 @@
+QA output created by 805
+test_file_handles after cycle mount
-- 
2.43.0

[PATCH v3 9/9] fstests: btrfs: test UUID consistency for clones with metadata_uuid

[Anand Jain]

Btrfs uses the metadata_uuid superblock feature to change the on-disk UUID
without rewriting every block header. This patch adds a sanity check to
ensure UUID consistency when a filesystem with metadata_uuid enabled is
cloned.

Signed-off-by: Anand Jain <asj@kernel.org>
---
 tests/btrfs/348     | 91 +++++++++++++++++++++++++++++++++++++++++++++
 tests/btrfs/348.out | 19 ++++++++++
 2 files changed, 110 insertions(+)
 create mode 100644 tests/btrfs/348
 create mode 100644 tests/btrfs/348.out

diff --git a/tests/btrfs/348 b/tests/btrfs/348
new file mode 100644
index 000000000000..cfa56fdb4a4a
--- /dev/null
+++ b/tests/btrfs/348
@@ -0,0 +1,91 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2026 Anand Jain <asj@kernel.org>.  All Rights Reserved.
+#
+# FS QA Test 348
+#
+# Verify that the cloned filesystem UUID remains consistent, even when the
+# `metadata_uuid` feature is enabled.
+#
+
+. ./common/preamble
+. ./common/filter
+
+_begin_fstest auto quick mount clone
+
+_require_test
+_require_loop
+
+_cleanup()
+{
+	cd /
+	rm -r -f $tmp.*
+	umount $mnt1 $mnt2 2>/dev/null
+	_loop_image_destroy "${devs[@]}" 2> /dev/null
+}
+
+filter_pool()
+{
+	sed -e "s|${devs[0]}|DEV1|g" -e "s|${mnt1}|MNT1|g" \
+	    -e "s|${devs[1]}|DEV2|g" -e "s|${mnt2}|MNT2|g" | _filter_spaces
+}
+
+pre_clone_tune()
+{
+	local temp_mnt=$TEST_DIR/${seq}_mnt
+
+	_require_command "$BTRFS_TUNE_PROG" btrfstune
+	mkdir -p $temp_mnt
+	_mount ${devs[0]} $temp_mnt
+	$BTRFS_UTIL_PROG subvolume create $temp_mnt/sv1 &> /dev/null
+	_unmount $temp_mnt
+	rm -r -f $temp_mnt
+
+	$BTRFS_TUNE_PROG -m ${devs[0]}
+}
+
+print_info()
+{
+	local mntpt=$1
+	local tgt=$(findmnt -no SOURCE $mntpt)
+	local fsuuid=$(blkid -s UUID -o value $tgt)
+
+	echo "mntpt=$mntpt tgt=$tgt fsuuid=$fsuuid" >> $seqres.full
+	echo
+	findmnt -o SOURCE,TARGET,UUID "$tgt" | tail -n +2 | \
+				sed -e "s/${fsuuid}/FSUUID/g" | filter_pool
+	awk -v dev="$tgt" '$1 == dev { print $1, $2 }' /proc/self/mounts | \
+								filter_pool
+	df --all --output=source,target "$tgt" | tail -n +2 | filter_pool
+}
+
+devs=()
+_loop_image_create_clone devs pre_clone_tune
+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"
+
+print_info $mnt1
+print_info $mnt2
+
+echo
+echo "**** mount cycle ****"
+_unmount $mnt1
+_unmount $mnt2
+_mount $(_common_dev_mount_options) $(_clone_mount_option) ${devs[1]} $mnt2 || \
+						_fail "Failed to mount dev2"
+_mount $(_common_dev_mount_options) $(_clone_mount_option) ${devs[0]} $mnt1 || \
+						_fail "Failed to mount dev1"
+
+print_info $mnt1
+print_info $mnt2
+
+status=0
+exit
diff --git a/tests/btrfs/348.out b/tests/btrfs/348.out
new file mode 100644
index 000000000000..4b102e986246
--- /dev/null
+++ b/tests/btrfs/348.out
@@ -0,0 +1,19 @@
+QA output created by 348
+
+DEV1 MNT1 FSUUID
+DEV1 MNT1
+DEV1 MNT1
+
+DEV2 MNT2 FSUUID
+DEV2 MNT2
+DEV2 MNT2
+
+**** mount cycle ****
+
+DEV1 MNT1 FSUUID
+DEV1 MNT1
+DEV1 MNT1
+
+DEV2 MNT2 FSUUID
+DEV2 MNT2
+DEV2 MNT2
-- 
2.43.0

Re: [PATCH v3 3/9] fstests: add test for inotify isolation on cloned devices

[Amir Goldstein]

On Mon, Apr 27, 2026 at 12:20 PM Anand Jain <asj@kernel.org> wrote:
>
> Add a new test, to verify that the kernel correctly differentiates between
> two block devices sharing the same FSID/UUID.
>
> Signed-off-by: Anand Jain <asj@kernel.org>

Reviewed-by: Amir Goldstein <amir73il@gmail.com>

> ---
>  common/config         |  1 +
>  tests/generic/800     | 88 +++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/800.out |  7 ++++
>  3 files changed, 96 insertions(+)
>  create mode 100644 tests/generic/800
>  create mode 100644 tests/generic/800.out
>
> diff --git a/common/config b/common/config
> index 4fd4c2c8af11..605a57947a40 100644
> --- a/common/config
> +++ b/common/config
> @@ -242,6 +242,7 @@ export BTRFS_MAP_LOGICAL_PROG=$(type -P btrfs-map-logical)
>  export PARTED_PROG="$(type -P parted)"
>  export XFS_PROPERTY_PROG="$(type -P xfs_property)"
>  export FSCRYPTCTL_PROG="$(type -P fscryptctl)"
> +export INOTIFYWAIT_PROG="$(type -P inotifywait)"
>
>  # udev wait functions.
>  #
> diff --git a/tests/generic/800 b/tests/generic/800
> new file mode 100644
> index 000000000000..16bc1159a2e1
> --- /dev/null
> +++ b/tests/generic/800
> @@ -0,0 +1,88 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2026 Anand Jain <asj@kernel.org>.  All Rights Reserved.
> +#
> +# FS QA Test 800
> +#
> +# Verify if the kernel or userspace becomes confused when two block devices
> +# share the same fid/fsid/uuid. Create inotify on both original and cloned
> +# filesystem. Monitor the notification in the respective logs.
> +
> +. ./common/preamble
> +
> +_begin_fstest auto quick mount clone
> +
> +_require_test
> +_require_loop
> +_require_command "$INOTIFYWAIT_PROG" inotifywait
> +
> +_cleanup()
> +{
> +       cd /
> +       [[ -n $pid1 ]] && { kill -TERM "$pid1" 2> /dev/null; wait $pid1; }
> +       [[ -n $pid2 ]] && { kill -TERM "$pid2" 2> /dev/null; wait $pid2; }
> +       rm -r -f $tmp.*
> +       _unmount $mnt1 2>/dev/null
> +       _unmount $mnt2 2>/dev/null
> +       _loop_image_destroy "${devs[@]}" 2> /dev/null
> +}
> +
> +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]} $mnt2 || \
> +                                               _fail "Failed to mount dev2"
> +
> +log1=$tmp.inotify1
> +log2=$tmp.inotify2
> +
> +pid1=""
> +pid2=""
> +echo "Setup inotify watchers on both mnt1 and mnt2"
> +$INOTIFYWAIT_PROG -m -e create --format '%f' $mnt1 > $log1 2>&1 &
> +pid1=$!
> +$INOTIFYWAIT_PROG -m -e create --format '%f' $mnt2 > $log2 2>&1 &
> +pid2=$!
> +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 inotify isolation"
> +kill $pid1 $pid2
> +wait $pid1 $pid2 2>/dev/null
> +pid1=""
> +pid2=""
> +
> +if grep -q "file_on_mnt1" $log1 && ! grep -q "file_on_mnt2" $log1; then
> +       echo "SUCCESS: mnt1 events isolated."
> +else
> +       echo "FAIL: mnt1 inotify confusion!"
> +       [ ! -s $log1 ] && echo "  - mnt1 received no events."
> +       grep -q "file_on_mnt2" $log1 && echo "  - mnt1 received event from mnt2."
> +fi
> +
> +if grep -q "file_on_mnt2" $log2 && ! grep -q "file_on_mnt1" $log2; then
> +       echo "SUCCESS: mnt2 events isolated."
> +else
> +       echo "FAIL: mnt2 inotify confusion!"
> +       [ ! -s $log2 ] && echo "  - mnt2 received no events."
> +       grep -q "file_on_mnt1" $log2 && echo "  - mnt2 received event from mnt1."
> +fi
> +
> +status=0
> +exit
> diff --git a/tests/generic/800.out b/tests/generic/800.out
> new file mode 100644
> index 000000000000..b10842a31210
> --- /dev/null
> +++ b/tests/generic/800.out
> @@ -0,0 +1,7 @@
> +QA output created by 800
> +Setup inotify watchers on both mnt1 and mnt2
> +Trigger file creation on mnt1
> +Trigger file creation on mnt2
> +Verify inotify isolation
> +SUCCESS: mnt1 events isolated.
> +SUCCESS: mnt2 events isolated.
> --
> 2.43.0
>

Re: [PATCH v3 1/9] fstests: add _loop_image_create_clone() helper

[Amir Goldstein]

On Mon, Apr 27, 2026 at 12:19 PM Anand Jain <asj@kernel.org> wrote:
>
> Introduce _loop_image_create_clone() and _loop_image_destroy() to mkfs an
> image file and clone it to another image file, and attach a loop device to
> them. And its destroy part.
>
> Signed-off-by: Anand Jain <asj@kernel.org>
> ---
>  common/rc | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 44 insertions(+)
>
> diff --git a/common/rc b/common/rc
> index 9632b211b58f..0e7b7eb1d98f 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -1503,6 +1503,50 @@ _scratch_resvblks()
>         esac
>  }
>
> +_loop_image_create_clone()
> +{
> +       local -n _ret=$1
> +       local pre_clone_tune_func=$2
> +       local img_file=$TEST_DIR/${seq}.img
> +       local img_file_clone=$TEST_DIR/${seq}_clone.img
> +       local size=$(_small_fs_size_mb 128) # Smallest possible
> +       local loop_devs
> +
> +       size=$((size * 1024 * 1024))
> +       $XFS_IO_PROG -f -c "truncate $size" $img_file
> +
> +       loop_devs=$(_create_loop_device $img_file)
> +       _ret=($loop_devs)
> +
> +       case $FSTYP in
> +       xfs)
> +               _mkfs_dev "-s size=4096" $img_file
> +               ;;
> +       btrfs)
> +               _mkfs_dev $img_file
> +               ;;
> +       *)
> +               _mkfs_dev $img_file

You making a wrong assumption that FSTYP can format the loop devices

You should add _require_block_device $SCRATCH_DEV
to all your tests or maybe nicer, add:

_require_loop_mountable which requires loop and block dev fs
and use this requirement instead of just _require_loop in all tests.

Thanks,
Amir.

Re: [PATCH v3 4/9] fstests: verify fanotify isolation on cloned filesystems

[Amir Goldstein]

On Mon, Apr 27, 2026 at 12:20 PM Anand Jain <asj@kernel.org> 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 <asj@kernel.org>
> ---
>  common/config         |   1 +
>  tests/generic/801     | 115 ++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/801.out |   7 +++
>  3 files changed, 123 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..3f64e4de2206
> --- /dev/null
> +++ b/tests/generic/801
> @@ -0,0 +1,115 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2026 Anand Jain <asj@kernel.org>.  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_loop

insufficient check for mounting a blockdev fs

> +_require_command "$FSNOTIFYWAIT_PROG" fsnotifywait
> +
> +[ "$FSTYP" = "ext4" ] && _fixed_by_kernel_commit xxxxxxxxxxxx \

Fix before merging

Other than that it looks ok.

Thanks,
Amir.

> +       "ext4: derive f_fsid from block device to avoid collisions"
> +
> +_cleanup()
> +{
> +       cd /
> +       [[ -n $pid1 ]] && { kill -TERM "$pid1" 2> /dev/null; wait $pid1; }
> +       [[ -n $pid2 ]] && { kill -TERM "$pid2" 2> /dev/null; wait $pid2; }
> +       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=$tmp.fanotify2
> +
> +pid1=""
> +pid2=""
> +echo "Setup FID fanotify watchers on both mnt1 and mnt2"
> +( monitor_fanotify "$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
>

Re: [PATCH v3 1/9] fstests: add _loop_image_create_clone() helper

[Anand Jain]

On 28/4/26 02:31, Amir Goldstein wrote:
> On Mon, Apr 27, 2026 at 12:19 PM Anand Jain <asj@kernel.org> wrote:
>>
>> Introduce _loop_image_create_clone() and _loop_image_destroy() to mkfs an
>> image file and clone it to another image file, and attach a loop device to
>> them. And its destroy part.
>>
>> Signed-off-by: Anand Jain <asj@kernel.org>
>> ---
>>  common/rc | 44 ++++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 44 insertions(+)
>>
>> diff --git a/common/rc b/common/rc
>> index 9632b211b58f..0e7b7eb1d98f 100644
>> --- a/common/rc
>> +++ b/common/rc
>> @@ -1503,6 +1503,50 @@ _scratch_resvblks()
>>         esac
>>  }
>>
>> +_loop_image_create_clone()
>> +{
>> +       local -n _ret=$1
>> +       local pre_clone_tune_func=$2
>> +       local img_file=$TEST_DIR/${seq}.img
>> +       local img_file_clone=$TEST_DIR/${seq}_clone.img
>> +       local size=$(_small_fs_size_mb 128) # Smallest possible
>> +       local loop_devs
>> +
>> +       size=$((size * 1024 * 1024))
>> +       $XFS_IO_PROG -f -c "truncate $size" $img_file
>> +
>> +       loop_devs=$(_create_loop_device $img_file)
>> +       _ret=($loop_devs)
>> +
>> +       case $FSTYP in
>> +       xfs)
>> +               _mkfs_dev "-s size=4096" $img_file
>> +               ;;
>> +       btrfs)
>> +               _mkfs_dev $img_file
>> +               ;;
>> +       *)
>> +               _mkfs_dev $img_file
> 
> You making a wrong assumption that FSTYP can format the loop devices
> 
> You should add _require_block_device $SCRATCH_DEV
> to all your tests or maybe nicer, add:
> 
> _require_loop_mountable which requires loop and block dev fs
> and use this requirement instead of just _require_loop in all tests.
> 

Thanks. I've fixed this in v4 by adding
  _require_block_device $TEST_DEV
Since SCRATCH_DEV is not required.

I didn't create a new _require_loop_mountable() helper.
Both _require_loop() and _require_block_device() are
used both together across other existing tests;
I prefer not to deviate into cleaning that up in this
patch set.

v4 is in the ML for rvb.

Thanks, Anand


> Thanks,
> Amir.