On Sat, Oct 28, 2023 at 03:01:23PM +0800, Baokun Li wrote:
> Append writes to a file approaching 16T and observe if a kernel crash is
> caused by ext4_lblk_t overflow triggering BUG_ON at ext4_mb_new_inode_pa().
> This is a regression test for commit bc056e7163ac ("ext4: fix BUG in
> ext4_mb_new_inode_pa() due to overflow")
>
> Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>
> ---
Hi Baokun,
Thanks for this new coverage, some review points as below ...
> tests/ext4/062 | 53 ++++++++++++++++++++++++++++++++++++++++++++++
> tests/ext4/062.out | 2 ++
> 2 files changed, 55 insertions(+)
> create mode 100755 tests/ext4/062
> create mode 100644 tests/ext4/062.out
>
> diff --git a/tests/ext4/062 b/tests/ext4/062
> new file mode 100755
> index 00000000..0ae4ed80
> --- /dev/null
> +++ b/tests/ext4/062
> @@ -0,0 +1,53 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2023 HUAWEI. All Rights Reserved.
> +#
> +# FS QA Test No. 062
> +#
> +# Append writes to a file approaching 16T and observe if a kernel crash is
> +# caused by ext4_lblk_t overflow triggering BUG_ON at ext4_mb_new_inode_pa().
> +# This is a regression test for commit
> +# bc056e7163ac ("ext4: fix BUG in ext4_mb_new_inode_pa() due to overflow")
> +#
> +. ./common/preamble
> +_begin_fstest auto quick insert
^^^
prealloc
> +
> +# real QA test starts here
> +_supported_fs ext4
> +_fixed_by_kernel_commit bc056e7163ac \
> + "ext4: fix BUG in ext4_mb_new_inode_pa() due to overflow"
> +
> +_require_xfs_io_command "falloc"
> +_require_xfs_io_command "open"
> +_require_xfs_io_command "pwrite"
I think we don't need to check the "open" and "pwrite" operations,
if you don't need special option for them.
> +_require_scratch_size_nocheck $((100 * 1024)) # 100MB in KB
I think 100MB is small enough, don't need this check.
> +
> +# Initalize a 4k 100M ext4 fs
> +dev_size=$((100 * 1024 * 1024))
> +MKFS_OPTIONS="-b 4096 $MKFS_OPTIONS" _scratch_mkfs_sized $dev_size \
> + >>$seqres.full 2>&1 || _fail "mkfs failed"
Can we use bsize=$(_get_file_block_size ....) to get the real block size,
to avoid use a specific mkfs option?
If so, my second question is if this case can be a generic case. The test
steps look common enough, I'm glad to see what will happen on other
filesystems through this test.
> +
> +_scratch_mount
> +
> +# Reserve 1M space
> +$XFS_IO_PROG -f -c "falloc 0 1M" "${SCRATCH_MNT}/tmp" >> $seqres.full 2>&1
> +
> +# Create a file with logical block numbers close to overflow
> +$XFS_IO_PROG -f -c "falloc 0 10M" "${SCRATCH_MNT}/file" >> $seqres.full 2>&1
> +$XFS_IO_PROG -f -c "finsert 1M 16777203M" "${SCRATCH_MNT}/file" >> $seqres.full 2>&1
_require_xfs_io_command "finsert"
> +
> +# Filling up the free space ensures that the pre-allocated space is the reserved space.
> +$XFS_IO_PROG -f -c "falloc 0 80388096" "${SCRATCH_MNT}/fill" >> $seqres.full 2>&1
Can we make sure this step fill the whole free space? There's a helper in
common/populate named _fill_fs, please check if it's what you want?
> +
> +# Remove reserved space to gain free space for allocation
> +rm -f ${SCRATCH_MNT}/tmp
> +
> +# Trying to allocate two blocks triggers BUG_ON.
> +$XFS_IO_PROG -c "open -ad ${SCRATCH_MNT}/file" -c "pwrite -S 0xff 0 8192" >> $seqres.full 2>&1
Oh, you need open -d option, that means you need direct IO, so you need:
_require_odirect
And all above xfs_io commands, include falloc, finsert, open and pwrite.
You can redirect the stdout to $seqres.full, but better *not* to change
the stderr, for we can find errors if they fail (except that expected ENOSPC).
> +
> +umount "${SCRATCH_MNT}"
The $SCRATCH_MNT will be unmounted at the end of the testing, don't need to do
it manually, except this's a necessary step of the reproducer.
> +echo "Silence is golden"
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/ext4/062.out b/tests/ext4/062.out
> new file mode 100644
> index 00000000..a1578f48
> --- /dev/null
> +++ b/tests/ext4/062.out
> @@ -0,0 +1,2 @@
> +QA output created by 062
> +Silence is golden
> --
> 2.31.1
>
>
