linux-ext4 - Re: [PATCH RFC 5/8] ext4: use super write guard in write_mmp

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Message-ID: <CAPjX3FeEZd7gX1OeCxRXrdBMafHOONB2WQO_JOZuxKoVEygzuQ@mail.gmail.com>
Date: Wed, 5 Nov 2025 19:33:35 +0100
From: Daniel Vacek <neelx@...e.com>
To: Christian Brauner <brauner@...nel.org>
Cc: linux-fsdevel@...r.kernel.org, Alexander Viro <viro@...iv.linux.org.uk>, 
	Jan Kara <jack@...e.cz>, linux-btrfs@...r.kernel.org, linux-ext4@...r.kernel.org, 
	linux-xfs@...r.kernel.org
Subject: Re: [PATCH RFC 5/8] ext4: use super write guard in write_mmp_block()

On Tue, 4 Nov 2025 at 13:16, Christian Brauner <brauner@...nel.org> wrote:
>
> Signed-off-by: Christian Brauner <brauner@...nel.org>
> ---
>  fs/ext4/mmp.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
>
> diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
> index ab1ff51302fb..6f57c181ff77 100644
> --- a/fs/ext4/mmp.c
> +++ b/fs/ext4/mmp.c
> @@ -57,16 +57,12 @@ static int write_mmp_block_thawed(struct super_block *sb,
>
>  static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
>  {
> -       int err;
> -
>         /*
>          * We protect against freezing so that we don't create dirty buffers
>          * on frozen filesystem.
>          */
> -       sb_start_write(sb);
> -       err = write_mmp_block_thawed(sb, bh);
> -       sb_end_write(sb);
> -       return err;
> +       scoped_guard(super_write, sb)
> +               return write_mmp_block_thawed(sb, bh);

Why the scoped_guard here? Should the simple guard(super_write)(sb) be
just as fine here?

--nX

>  }
>
>  /*
>
> --
> 2.47.3
>
>