On Wed, Oct 31, 2018 at 11:55 AM Miklos Szeredi <mszeredi@xxxxxxxxxx> wrote:
>
> There's a bug in the overlayfs implementation starting from the very first
> merged version that may cause an Oops of various forms if a directory is created
> over a whiteout dentry, but the actual whiteout on the upper layer was removed
> to the directory creation.
>
> Reported by: kaixuxia <xiakaixu1987@xxxxxxxxx>
> Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
> ---
Looks good. A bit of commentary could be useful...
> tests/overlay/062 | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++
> tests/overlay/062.out | 2 ++
> tests/overlay/group | 1 +
> 3 files changed, 63 insertions(+)
> create mode 100644 tests/overlay/062
> create mode 100644 tests/overlay/062.out
>
> diff --git a/tests/overlay/062 b/tests/overlay/062
> new file mode 100644
> index 000000000000..b2cc350afefb
> --- /dev/null
> +++ b/tests/overlay/062
> @@ -0,0 +1,60 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2018 Red Hat Inc. All Rights Reserved.
> +#
> +# FS QA Test 062
> +#
> +# Create dir over cached negative dentry, but whiteout removed from upper
> +#
> +# The following kernel commit fixed the kernel crash: ???
> +#
> +seq=`basename $0`
> +seqres=$RESULT_DIR/$seq
> +echo "QA output created by $seq"
> +
> +here=`pwd`
> +tmp=/tmp/$$
> +status=1 # failure is the default!
> +trap "_cleanup; exit \$status" 0 1 2 3 15
> +
> +_cleanup()
> +{
> + cd /
> + rm -f $tmp.*
> +}
> +
> +# get standard environment, filters and checks
> +. ./common/rc
> +. ./common/filter
> +
> +# remove previous $seqres.full before test
> +rm -f $seqres.full
> +
> +# real QA test starts here
> +_supported_fs overlay
> +_supported_os Linux
> +_require_scratch
> +
> +# Remove all files from previous tests
> +_scratch_mkfs
> +
> +# Create test file
> +lowerdir=${OVL_BASE_SCRATCH_MNT}/${OVL_LOWER}
> +upperdir=${OVL_BASE_SCRATCH_MNT}/${OVL_UPPER}
> +mkdir -p $lowerdir
> +touch ${lowerdir}/file
> +
> +_scratch_mount
> +
# Create whiteout and populate dcache with negative dentry
> +rm ${SCRATCH_MNT}/file
> +ls -l ${SCRATCH_MNT}/file > /dev/null 2>&1
# Remove whiteout and try to create dir over negative dentry
> +rm ${upperdir}/file
> +mkdir ${SCRATCH_MNT}/file > /dev/null 2>&1
> +
> +# unmount overlayfs
> +$UMOUNT_PROG $SCRATCH_MNT
Umount of scratch is not needed at the end of the test.
Thanks,
Amir.
