[PATCH 2/2] fstests: btrfs/349: test if latest tree-log is choosen at mount time on raid1 profile

[Zhang Boyang <zhangboyang.id@gmail.com>]

This test simulate a scenario that tree-log only exists in secondary
device, and test if latest tree-log is choosen at mount time.

Currently, the tree-log in the device with lowest devid is choosen. So
fsync'ed data may loss if tree-log only exists in secondary device.

Signed-off-by: Zhang Boyang <zhangboyang.id@gmail.com>
---
 tests/btrfs/349     | 53 +++++++++++++++++++++++++++++++++++++++++++++
 tests/btrfs/349.out | 14 ++++++++++++
 2 files changed, 67 insertions(+)
 create mode 100755 tests/btrfs/349
 create mode 100644 tests/btrfs/349.out

diff --git a/tests/btrfs/349 b/tests/btrfs/349
new file mode 100755
index 00000000..40e966c6
--- /dev/null
+++ b/tests/btrfs/349
@@ -0,0 +1,53 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2026 Zhang Boyang.  All Rights Reserved.
+#
+# FS QA Test 349
+#
+# Test if latest tree-log is choosen at mount time on raid1 profile.
+#
+. ./common/preamble
+_begin_fstest auto quick read_repair raid
+
+. ./common/filter
+. ./common/fail_make_request
+
+_require_fail_make_request
+_require_scratch_dev_pool 2
+
+_scratch_dev_pool_get 2
+_check_minimal_fs_size $(( 1024 * 1024 * 1024 ))
+# a strong checksum like sha256 can't protect you
+_scratch_pool_mkfs "-m raid1 -d raid1 -b 1G --csum sha256" >> $seqres.full 2>&1
+dev2=`echo $SCRATCH_DEV_POOL | $AWK_PROG '{print $2}'`
+_allow_fail_make_request
+
+echo "Step 1: prepare filesystem"
+_scratch_mount -o treelog
+$XFS_IO_PROG -f -c "pwrite -W -S 0xaa 0 8" $SCRATCH_MNT/foobar | _filter_xfs_io
+_scratch_unmount
+
+echo "Step 2: simulate failure"
+_scratch_mount -o treelog
+# simulate dev1 disappears before writing anything
+_bdev_fail_make_request $SCRATCH_DEV 1
+# this write should success
+$XFS_IO_PROG -f -c "pwrite -W -S 0xbb 0 8" $SCRATCH_MNT/foobar | _filter_xfs_io
+# simulate dev2 disappears after writing TREE_LOG
+_bdev_fail_make_request $dev2 1
+_scratch_unmount
+_bdev_fail_make_request $SCRATCH_DEV 0
+_bdev_fail_make_request $dev2 0
+
+echo "Step 3: simulate recovery"
+# this mount should start tree-log replay
+_scratch_mount -o treelog
+echo "Step 4: verify written data"
+# read data should be 0xbb
+$XFS_IO_PROG -c "pread -v 0 8" $SCRATCH_MNT/foobar | _filter_xfs_io_offset
+_scratch_unmount
+
+_disallow_fail_make_request
+_scratch_dev_pool_put
+# success, all done
+_exit 0
diff --git a/tests/btrfs/349.out b/tests/btrfs/349.out
new file mode 100644
index 00000000..1ebf4dc9
--- /dev/null
+++ b/tests/btrfs/349.out
@@ -0,0 +1,14 @@
+QA output created by 349
+Allow global fail_make_request feature
+Step 1: prepare filesystem
+wrote 8/8 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+Step 2: simulate failure
+wrote 8/8 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+Step 3: simulate recovery
+Step 4: verify written data
+XXXXXXXX:  bb bb bb bb bb bb bb bb  ........
+read 8/8 bytes
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+Disallow global fail_make_request feature
-- 
2.53.0