Re: [f2fs-dev] [PATCH v4] f2fs/025: test to do sanity check section type correctly in f2fs GC

On Tue, Jun 16, 2026 at 07:35:26AM +0000, Chao Yu wrote:
> Without commit 520760b9f915 ("f2fs: optimize representative type determination
> in GC"), f2fs GC will report inconsistent segment type in large section issue,
> and then it will force to shutdown filesystem.
> 
> [  768.190903] F2FS-fs (loop51): Inconsistent segment (3) type [1, 0] in SIT and SSA
> 
> The reason is f2fs kernel will assume all segment type inside large section is
> the same, during GC it loads type from one segment and compare it to other
> segments' type, however due to recovery flow, the chosen segment may has zero
> valid blocks w/ different segment type, since the segment is invalid(free) one,
> it will never be migrated, so that we should not treat such state as abnormal
> condition.
> 
> This testcase is created to simulate above condition to see whether f2fs kernel
> module can handle it correctly
> 
> Signed-off-by: Chao Yu <[email protected]>
> ---
> v4:
> - add missing "_require_fs_sysfs_attr $TEST_DEV gc_urgent"

Thanks for updating, this version is good to me :)

Reviewed-by: Zorro Lang <[email protected]>

>  tests/f2fs/025     | 82 ++++++++++++++++++++++++++++++++++++++++++++++
>  tests/f2fs/025.out |  2 ++
>  2 files changed, 84 insertions(+)
>  create mode 100755 tests/f2fs/025
>  create mode 100644 tests/f2fs/025.out
> 
> diff --git a/tests/f2fs/025 b/tests/f2fs/025
> new file mode 100755
> index 000000000..807f18f23
> --- /dev/null
> +++ b/tests/f2fs/025
> @@ -0,0 +1,82 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2026 Chao Yu <[email protected]>
> +#
> +# FS QA Test No. f2fs/025
> +#
> +# Check whether f2fs will encounter cp_error (Inconsistent segment type)
> +# when doing sanity check on type of segments inside large section during
> +# garbage collection.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick
> +
> +_fixed_by_kernel_commit 520760b9f915 \
> +	"f2fs: optimize representative type determination in GC"
> +
> +. ./common/filter
> +
> +_require_scratch
> +_require_scratch_shutdown
> +_require_xfs_io_command "pwrite"
> +_require_xfs_io_command "truncate"
> +_require_command "$F2FS_IO_PROG" f2fs_io
> +_require_fs_sysfs_attr $TEST_DEV gc_urgent
> +_require_check_dmesg
> +
> +# Clear options to avoid interference from external configurations
> +export MKFS_OPTIONS=""
> +export MOUNT_OPTIONS=""
> +
> +# Format with 96MB size and 2 segments per section
> +_scratch_mkfs_sized $((96 * 1024 * 1024)) "" "-s 2" >> $seqres.full 2>&1
> +
> +# Mount with mode=lfs
> +_scratch_mount -o mode=lfs
> +
> +# Create files to fill whole filesystem, then segment type will be changed to node type
> +for ((i=0;i<5120;i++)) do
> +	touch $SCRATCH_MNT/$i >> $seqres.full 2>&1
> +done
> +sync
> +
> +# Remove all files to create free(empty) node segments
> +rm -f $SCRATCH_MNT/*
> +sync
> +
> +# Allocate free space so that we have chance to reuse free(empty) node segments
> +$XFS_IO_PROG -f -c "pwrite -b 4k 0 1928k" $SCRATCH_MNT/file >> $seqres.full 2>&1
> +sync
> +
> +$XFS_IO_PROG -c "truncate 0" $SCRATCH_MNT/file >> $seqres.full 2>&1
> +$XFS_IO_PROG -d -c "pwrite -b 4k 0 16M" $SCRATCH_MNT/file >> $seqres.full 2>&1
> +$XFS_IO_PROG -c "truncate 0" $SCRATCH_MNT/file >> $seqres.full 2>&1
> +$XFS_IO_PROG -d -c "pwrite -b 4k 0 16M" $SCRATCH_MNT/file >> $seqres.full 2>&1
> +$XFS_IO_PROG -c "truncate 0" $SCRATCH_MNT/file >> $seqres.full 2>&1
> +sync
> +
> +$XFS_IO_PROG -d -c "pwrite -b 4k 0 8M" $SCRATCH_MNT/file >> $seqres.full 2>&1
> +$XFS_IO_PROG -c "truncate 0" $SCRATCH_MNT/file >> $seqres.full 2>&1
> +$XFS_IO_PROG -d -c "pwrite -b 4k 0 32K" $SCRATCH_MNT/file >> $seqres.full 2>&1
> +$XFS_IO_PROG -c "truncate 0" $SCRATCH_MNT/file >> $seqres.full 2>&1
> +$XFS_IO_PROG -d -c "pwrite -b 4k 0 2M" -c "fsync" $SCRATCH_MNT/file >> $seqres.full 2>&1
> +
> +# Shutdown the filesystem without checkpoint
> +_scratch_shutdown
> +
> +_scratch_unmount
> +
> +_scratch_mount -o mode=lfs
> +
> +# Run urgent_gc mode to trigger garbage collection
> +dev_name=$(_short_dev $SCRATCH_DEV)
> +$F2FS_IO_PROG gc_urgent $dev_name run 5 >> $seqres.full
> +
> +_scratch_unmount
> +
> +# Check whether the dmesg has the warning indicating the bug
> +_check_dmesg_for "F2FS-fs \($dev_name\): Inconsistent segment" && \
> +	_fail "F2FS-fs ($dev_name): Inconsistent segment type detected in dmesg!"
> +
> +echo "Silence is golden"
> +_exit 0
> diff --git a/tests/f2fs/025.out b/tests/f2fs/025.out
> new file mode 100644
> index 000000000..3d70951ef
> --- /dev/null
> +++ b/tests/f2fs/025.out
> @@ -0,0 +1,2 @@
> +QA output created by 025
> +Silence is golden
> -- 
> 2.49.0
> 


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