On Fri, Jun 12, 2026 at 12:58:02AM +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]>
> ---
> v2:
> - clear MKFS_OPTIONS and MOUNT_OPTIONS to guarantee block allocation is as
> expected.
Hi Chao,
Sorry, I just noticed your reply to my review on the previous patch version.
Due to some unexpected shake-ups recently, I’ve been bogged down with setting
up and modifying various new system environments, and I accidentally marked
some unread emails as read.
The patch looks good to me, with just a few picky review points below:
> tests/f2fs/025 | 92 ++++++++++++++++++++++++++++++++++++++++++++++
> tests/f2fs/025.out | 2 +
> 2 files changed, 94 insertions(+)
> create mode 100644 tests/f2fs/025
> create mode 100644 tests/f2fs/025.out
>
> diff --git a/tests/f2fs/025 b/tests/f2fs/025
> new file mode 100644
> index 000000000..397e5439a
> --- /dev/null
> +++ b/tests/f2fs/025
> @@ -0,0 +1,92 @@
> +#! /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
> +
> +_cleanup()
> +{
> + cd /
> + rm -r -f $tmp.*
> +}
This _cleanup() function is same as default. It can be removed.
> +
> +_require_scratch
> +_require_xfs_io_command "pwrite"
> +_require_xfs_io_command "truncate"
> +_require_command "$F2FS_IO_PROG" f2fs_io
> +_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 >> $seqres.full 2>&1
^^^^^^^^^^^^^^^^^^^^
It's helpless, due to if _scratch_mount fails, it exit() directly.
> +
> +# 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 >>
> $seqres.full 2>&1
> +
> +# Shutdown the filesystem without checkpoint
> +$F2FS_IO_PROG shutdown 2 $SCRATCH_MNT >> $seqres.full 2>&1
I'm wondering if we can have f2fs supporting in common _scratch_shutdown
helper :)
> +
> +_scratch_unmount >> $seqres.full 2>&1
^^^^^^^^^^^^^^^^^^^^
If unmount fails, how about let it output the errors, to break the golden image?
> +
> +_scratch_mount -o mode=lfs >> $seqres.full 2>&1
^^^^^^^^^^^^^^^^^^^^
helpless
> +
> +# Run urgent_gc mode to trigger garbage collection
> +dev_name=$(_short_dev $SCRATCH_DEV)
> +if [ -f /sys/fs/f2fs/$dev_name/gc_urgent ]; then
> + echo 1 > /sys/fs/f2fs/$dev_name/gc_urgent
> +fi
Hmm... what if there's not /sys/fs/f2fs/$dev_name/gc_urgent? Does it
affect the test result?
If it does, this's a necessary requirement for this test, we shouldn't
ignore it and keep running. Does $F2FS_IO_PROG provide a command to
make a force GC? Or we need to check this file and _notrun if it's
not existed.
> +
> +# Wait background GC thread to wake up to run and potentially encounter the
> inconsistency
> +sleep 5
Does this sleep try to wait above "echo 1 > /sys/fs/f2fs/$dev_name/gc_urgent"?
If so, it makes more sense to move it into the "if-then" logic.
> +
> +_scratch_unmount >> $seqres.full 2>&1
^^^^^^^^^^^^^^^^^^^^
Same as above.
> +
> +# 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"
> +status=0
> +exit
We've replaced "status=0;exit;" with "_exit 0".
Thanks,
Zorro
> 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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