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Message-ID: <tencent_8CDB89A1076C8F0FE46F79120D40114BAC05@qq.com>
Date:   Fri, 15 Jul 2022 23:11:23 +0800
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Subject: Re: [PATCH] jbd2: Set the right uuid for block tag
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To:     linux-ext4@vger.kernel.org
References: <tencent_D668868A37626B4E053D6D7B5320DBCB1C08@qq.com>
From:   Wang Jianjian <wangjianjian0@foxmail.com>
In-Reply-To: <tencent_D668868A37626B4E053D6D7B5320DBCB1C08@qq.com>
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Hi all,
Is this a real problem need to fix ?

On 7/12/22 00:26, Wang Jianjian wrote:
> journal->j_uuid is not initialized and let us use the uuid from
> j_superblock. And since this is the only place where j_uuid is used
> so that we can remove it.
> 
> Signed-off-by: Wang Jianjian <wangjianjian0@foxmail.com>
> ---
>   fs/jbd2/commit.c     |  2 +-
>   include/linux/jbd2.h | 10 ----------
>   2 files changed, 1 insertion(+), 11 deletions(-)
> 
> diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
> index 5b9408e3b370..efde9c494e7a 100644
> --- a/fs/jbd2/commit.c
> +++ b/fs/jbd2/commit.c
> @@ -720,7 +720,7 @@ void jbd2_journal_commit_transaction(journal_t *journal)
>   		bufs++;
>   
>   		if (first_tag) {
> -			memcpy (tagp, journal->j_uuid, 16);
> +			memcpy (tagp, journal->j_superblock->s_uuid, 16);
>   			tagp += 16;
>   			space_left -= 16;
>   			first_tag = 0;
> diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
> index de9536680b2b..9d51f4b55cb5 100644
> --- a/include/linux/jbd2.h
> +++ b/include/linux/jbd2.h
> @@ -1079,16 +1079,6 @@ struct journal_s
>   	 */
>   	tid_t			j_commit_request;
>   
> -	/**
> -	 * @j_uuid:
> -	 *
> -	 * Journal uuid: identifies the object (filesystem, LVM volume etc)
> -	 * backed by this journal.  This will eventually be replaced by an array
> -	 * of uuids, allowing us to index multiple devices within a single
> -	 * journal and to perform atomic updates across them.
> -	 */
> -	__u8			j_uuid[16];
> -
>   	/**
>   	 * @j_task: Pointer to the current commit thread for this journal.
>   	 */
>