Re: [PATCH] btrfs: add a test case to check btrfs won't crash on certain corruption

[Anand Jain <anand.jain@oracle.com>]

  Added to local branch with the following changed. Under testing.

On 25/02/2023 17:14, Qu Wenruo wrote:
> There seems to be a newly introduced regression that btrfs no longer
> properly handles critical errors during mount.
> 
> Such regression lead to crash when mounting an fs with a corrupted tree
> root.
> 

We can now remove this, as we have identified and resolved a regression
in a local branch. The fix went into

   [PATCH] btrfs: move all btree initialization into btrfs_init_btree_inode


> The test case would reproduce the situation by creating an empty fs,
> with SINGLE metadata profile, then corrupt the tree root manually.
> Finally try mounting the corrupted fs, the mount should fail while our
> kernel should not fail.
> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> ---
> The fix is titled "btrfs: fix the mount crash caused by confusing return
> value", and is already submitted to the btrfs list.
> 
> Unfortunately git blame doesn't give a good enough clue on which commit
> introduced the regression.

> ---
>   tests/btrfs/288     | 37 +++++++++++++++++++++++++++++++++++++
>   tests/btrfs/288.out |  2 ++
>   2 files changed, 39 insertions(+)
>   create mode 100755 tests/btrfs/288
>   create mode 100644 tests/btrfs/288.out
> 
> diff --git a/tests/btrfs/288 b/tests/btrfs/288
> new file mode 100755
> index 00000000..029603c8
> --- /dev/null
> +++ b/tests/btrfs/288
> @@ -0,0 +1,37 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (C) 2023 SUSE Linux Products GmbH. All Rights Reserved.
> +#
> +# FS QA Test 288
> +#
> +# Make sure btrfs handles critical errors gracefully during mount.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick dangerous
> +
> +. ./common/filter
> +_supported_fs btrfs
> +_require_scratch
> +
> +# Use single metadata profile so we only need to corrupt one copy of tree block
> +_scratch_mkfs -m single > $seqres.full
> +

> +logical_root=$($BTRFS_UTIL_PROG inspect dump-tree -t root "$SCRATCH_DEV" | grep leaf | head -n1 | cut -f2 -d\  )

  Fixed 80-char length.

> +physical_root=$(_btrfs_get_physical $logical_root 1)
> +
> +echo "tree root logical=$logical_root" >> $seqres.full
> +echo "tree root physical=$physical_root" >> $seqres.full
> +
> +_pwrite_byte 0x00 "$physical_root" 4 $SCRATCH_DEV > $seqres.full

  Append $seqres.full

> +
> +# For unpatched kernel, the mount may lead to crash

  Fix comment.

> +_try_scratch_mount >> $seqres.full 2>&1
> +
> +echo "Silence is golden"
> +
> +# Re-create the fs to avoid false alert from the corrupted fs.
> +_scratch_mkfs -m single > $seqres.full

  Append $seqres.full

Thanks, Anand

> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/btrfs/288.out b/tests/btrfs/288.out
> new file mode 100644
> index 00000000..2958a5c3
> --- /dev/null
> +++ b/tests/btrfs/288.out
> @@ -0,0 +1,2 @@
> +QA output created by 288
> +Silence is golden