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Date:   Thu, 4 Aug 2022 02:28:43 +0800
From:   Zorro Lang <zlang@redhat.com>
To:     "Darrick J. Wong" <djwong@kernel.org>
Cc:     linux-xfs@vger.kernel.org, fstests@vger.kernel.org, tytso@mit.edu,
        linux-ext4@vger.kernel.org
Subject: Re: [PATCH 3/3] common/ext4: provide custom ext4 scratch fs options
Message-ID: <20220803182843.mznuba2z7mbti4co@zlang-mailbox>
References: <165950050051.198922.13423077997881086438.stgit@magnolia>
 <165950051745.198922.6487109955066878945.stgit@magnolia>
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On Tue, Aug 02, 2022 at 09:21:57PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> Create a _scratch_options backend for ext* so that we can inject
> pathnames to external log devices into the scratch fs mount options.
> This enables common/dm* to install block device filters, e.g. dm-error
> for stress testing.
> 
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---
>  common/ext4 |   20 ++++++++++++++++++++
>  common/rc   |    3 +++
>  2 files changed, 23 insertions(+)
> 
> 
> diff --git a/common/ext4 b/common/ext4
> index 287705af..819f9786 100644
> --- a/common/ext4
> +++ b/common/ext4
> @@ -154,3 +154,23 @@ _require_scratch_richacl_ext4()
>  		|| _notrun "kernel doesn't support richacl feature on $FSTYP"
>  	_scratch_unmount
>  }
> +
> +_scratch_ext4_options()
> +{
> +    local type=$1
> +    local log_opt=""
> +
> +    case $type in
> +    mkfs)
> +        log_opt="-J device=$SCRATCH_LOGDEV"

In _scratch_mkfs_ext4, it deals with mkfs with SCRATCH_LOGDEV:

  [ "$USE_EXTERNAL" = yes -a ! -z "$SCRATCH_LOGDEV" ] && \
     $mkfs_cmd -O journal_dev $MKFS_OPTIONS $SCRATCH_LOGDEV && \
     mkfs_cmd="$mkfs_cmd -J device=$SCRATCH_LOGDEV"

So is there a conflict or duplication?

> +	;;
> +    mount)
> +	# As of kernel 5.19, the kernel mount option path parser only accepts
> +	# direct paths to block devices--the final path component cannot be a
> +	# symlink.
> +        log_opt="-o journal_path=$(realpath $SCRATCH_LOGDEV)"
> +	;;
> +    esac
> +    [ "$USE_EXTERNAL" = yes -a ! -z "$SCRATCH_LOGDEV" ] && \
> +	SCRATCH_OPTIONS="$SCRATCH_OPTIONS ${log_opt}"
> +}
> diff --git a/common/rc b/common/rc
> index dc1d65c3..b82bb36b 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -178,6 +178,9 @@ _scratch_options()
>      "xfs")
>  	_scratch_xfs_options "$@"
>  	;;
> +    ext2|ext3|ext4|ext4dev)
> +	_scratch_ext4_options "$@"
> +	;;
>      esac
>  }
>  
>