On 5/7/25 13:08, Zorro Lang wrote:
> On Tue, Apr 15, 2025 at 05:38:22PM +0800, Chao Yu wrote:
>> As Han Qi reported in bugzilla [1], commit 5c26d2f1d3f5 ("unicode: Don't
>> special case ignorable code points") changes logic to handle ignorable
>> code points, when we handle filename which has special unicode charactor
>> like red heart ❤️, utf8_casefold() may return different length than in the
>> past, result in that f2fs cacluates hash code incorreclty, eventually,
>> filename w/ special unicode charactor will not be found w/ the wrong hash
>> code.
>>
>> f2fs has introduces a linear lookup fallback w/ commit 91b587ba79e1
>> ("f2fs: Introduce linear search for dentries"), once hash-based lookup
>> fails, it tries linear lookup as a fallback.
>>
>> This patch can help to check whether linear lookup fallback works well
>> or not.
>>
>> Firstly, we use below testcase to check how hash code changes:
>>
>> mkfs.f2fs -f -O casefold -C utf8 /dev/vda
>> mount /dev/vda /mnt/f2fs
>> mkdir /mnt/f2fs/dir/
>> f2fs_io setflags casefold /mnt/f2fs/dir
>> touch /mnt/f2fs/dir/$'\u2764\ufe0f'
>> umount /mnt/f2fs
>> dump.f2fs -i 4 -d 3 /dev/vda
>> dump.f2fs -b $blkaddr_of_dir -d 3 /dev/vda
>>
>> w/o ("unicode: Don't special case ignorable code points")
>> [dump_dirent: 991] bitmap pos[0x2] name[❤️] len[0x6] hash[0x19dd7132]
>> ino[0x5] type[0x1]
>> [dump_dirent: 998] name(hex)[0xe2 0x9d 0xa4 0xef 0xb8 0x8f 0x0]
>>
>> w/ ("unicode: Don't special case ignorable code points")
>> [dump_dirent: 991] bitmap pos[0x2] name[❤️] len[0x6] hash[0x9a2ea068]
>> ino[0x5] type[0x1]
>> [dump_dirent: 998] name(hex)[0xe2 0x9d 0xa4 0xef 0xb8 0x8f 0x0]
>>
>> Correct hash code: 0x19dd7132
>> Wrong hash code: 0x9a2ea068
>>
>> So, we can test as below:
>>
>> 1. create file w/ red heart as its filename
>> 2. inject wrong hash code to the file
>> 3. disable linear lookup, expect lookup failure
>> 4. enable linear lookup, expect lookup succeed
>>
>> [1] https://bugzilla.kernel.org/show_bug.cgi?id=219586
>>
>> Cc: Jaegeuk Kim <jaeg...@kernel.org>
>> Cc: Daniel Lee <chul...@google.com>
>> Signed-off-by: Chao Yu <c...@kernel.org>
>> ---
>
> Sorry for this late review, this verssion looks good to me, just one review
> point
> as below ..
>
>> v2:
>> - tune linear_lookup feature before fault injection
>> - check status after tuning linear_lookup feature
>> - clean up codes
>> tests/f2fs/012 | 73 ++++++++++++++++++++++++++++++++++++++++++++++
>> tests/f2fs/012.out | 2 ++
>> 2 files changed, 75 insertions(+)
>> create mode 100755 tests/f2fs/012
>> create mode 100644 tests/f2fs/012.out
>>
>> diff --git a/tests/f2fs/012 b/tests/f2fs/012
>> new file mode 100755
>> index 00000000..38a63f2e
>> --- /dev/null
>> +++ b/tests/f2fs/012
>> @@ -0,0 +1,73 @@
>> +#! /bin/bash
>> +# SPDX-License-Identifier: GPL-2.0
>> +# Copyright (c) 2025 Chao Yu. All Rights Reserved.
>> +#
>> +# FS QA Test No. f2fs/012
>> +#
>> +# This testcase checks whether linear lookup fallback works well
>> +# or not as below:
>> +# 1.create file w/ red heart as its filename
>> +# 2.inject wrong hash code to the file
>> +# 3.disable linear lookup, expect lookup failure
>> +# 4.enable linear lookup, expect lookup succeed
>> +#
>> +. ./common/preamble
>> +_begin_fstest auto quick casefold
>> +
>> +_fixed_by_kernel_commit 91b587ba79e1 \
>> + "f2fs: Introduce linear search for dentries"
>> +
>> +export LC_ALL=C.UTF-8
>> +_require_scratch
>> +_require_command "$F2FS_IO_PROG" f2fs_io
>> +_require_command "$F2FS_INJECT_PROG" inject.f2fs
>> +
>> +check_lookup()
>> +{
>> + local nolinear_lookup=$1
>> + local dir=$SCRATCH_MNT/dir
>> + # red heart charactor in unicode format
>> + local redheart=$dir/$'\u2764\ufe0f'
>> +
>> + _scratch_mkfs -O casefold -C utf8 >> $seqres.full
>> + _scratch_mount
>> +
>> + mkdir $dir
>> + $F2FS_IO_PROG setflags casefold $dir >> $seqres.full
>> + touch $redheart
>> + ino=`stat -c '%i' $redheart`
>> + _scratch_unmount
>> +
>> + # should tune nolinear_lookup feature before fault injection
>> + $F2FS_FSCK_PROG --nolinear-lookup=$nolinear_lookup $SCRATCH_DEV >>
>> $seqres.full
>> +
>> + # check whether linear_lookup is changed as expected
>> + if [ $nolinear_lookup == "1" ]; then
>> + $F2FS_FSCK_PROG $SCRATCH_DEV | grep -q "linear_lookup
>> \[disable\]" || \
>> + _fail "linear_lookup is not disabled"
>> + else
>> + $F2FS_FSCK_PROG $SCRATCH_DEV | grep -q "linear_lookup
>> \[enable\]" || \
>> + _fail "linear_lookup is not enabled"
>> + fi
>> +
>> + $F2FS_INJECT_PROG --dent --mb d_hash --nid $ino --val 0x9a2ea068
>> $SCRATCH_DEV >> $seqres.full
>> +
>> + _scratch_mount
>> + if [ $nolinear_lookup == "1" ]; then
>> + [ -f $redheart ] && _fail "red heart file should not exist"
>> + else
>> + [ -f $redheart ] || _fail "red heart file should exist"
>> + fi
>> + _scratch_unmount
>> +
>> + # to avoid _check_filesystems failure in the end of test
>> + _repair_scratch_fs >> $seqres.full
>
> If you want to make sure "fsck.f2fs can repair above corruption", then this
> comment isn't right.
> If you just want to avoid _check_filesystems failure, you can replace
> _require_scratch with
> _require_scratch_nocheck, then remove this line.
Ah, let me use _require_scratch_nocheck instead, thanks. :)
Thanks,
>
> Thanks,
> Zorro
>
>> +}
>> +
>> +check_lookup 1
>> +check_lookup 0
>> +
>> +echo "Silence is golden"
>> +
>> +status=0
>> +exit
>> diff --git a/tests/f2fs/012.out b/tests/f2fs/012.out
>> new file mode 100644
>> index 00000000..3afeca2f
>> --- /dev/null
>> +++ b/tests/f2fs/012.out
>> @@ -0,0 +1,2 @@
>> +QA output created by 012
>> +Silence is golden
>> --
>> 2.49.0
>>
>
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