linux-ext4 - Re: [PATCH 4/5] jbd2: factor out journal initialization from journal_get

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Date:   Mon, 13 Mar 2023 12:12:53 +0100
From:   Jan Kara <jack@...e.cz>
To:     Zhihao Cheng <chengzhihao1@...wei.com>
Cc:     tytso@....edu, adilger.kernel@...ger.ca, jack@...e.com,
        linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        yi.zhang@...wei.com
Subject: Re: [PATCH 4/5] jbd2: factor out journal initialization from
 journal_get_superblock()

On Fri 10-03-23 20:52:05, Zhihao Cheng wrote:
> From: Zhang Yi <yi.zhang@...wei.com>
> 
> Current journal_get_superblock() couple journal superblock checking and
> partial journal initialization, factor out initialization part from it
> to make things clear.
> 
> Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
> Signed-off-by: Zhihao Cheng <chengzhihao1@...wei.com>
> ---
>  fs/jbd2/journal.c | 52 ++++++++++++++++++++---------------------------
>  1 file changed, 22 insertions(+), 30 deletions(-)

The patch looks mostly good. Just one style nit below.

> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index b991d5c21d16..cd94d068b4e6 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -1921,26 +1921,15 @@ static int journal_get_superblock(journal_t *journal)
>  		printk(KERN_WARNING "JBD2: no valid journal superblock found\n");
>  		goto out;
>  	}
> -
> -	switch(be32_to_cpu(sb->s_header.h_blocktype)) {
> -	case JBD2_SUPERBLOCK_V1:
> -		journal->j_format_version = 1;
> -		break;
> -	case JBD2_SUPERBLOCK_V2:
> -		journal->j_format_version = 2;
> -		break;
> -	default:
> +	if (be32_to_cpu(sb->s_header.h_blocktype) != JBD2_SUPERBLOCK_V1 &&
> +	    be32_to_cpu(sb->s_header.h_blocktype) != JBD2_SUPERBLOCK_V2) {
>  		printk(KERN_WARNING "JBD2: unrecognised superblock format ID\n");
>  		goto out;
>  	}
> -
> -	if (be32_to_cpu(sb->s_maxlen) < journal->j_total_len)
> -		journal->j_total_len = be32_to_cpu(sb->s_maxlen);
> -	else if (be32_to_cpu(sb->s_maxlen) > journal->j_total_len) {
> +	if (be32_to_cpu(sb->s_maxlen) > journal->j_total_len) {
>  		printk(KERN_WARNING "JBD2: journal file too short\n");
>  		goto out;
>  	}
> -

Please keep this empty line here. It actually makes the code more readable,
separating logically different checks. Same with three empty lines below...

>  	if (be32_to_cpu(sb->s_first) == 0 ||
>  	    be32_to_cpu(sb->s_first) >= journal->j_total_len) {
>  		printk(KERN_WARNING
> @@ -1956,7 +1945,6 @@ static int journal_get_superblock(journal_t *journal)
>  		       "at the same time!\n");
>  		goto out;
>  	}
> -
>  	if (jbd2_journal_has_csum_v2or3_feature(journal) &&
>  	    jbd2_has_feature_checksum(journal)) {
>  		/* Can't have checksum v1 and v2 on at the same time! */
> @@ -1964,12 +1952,10 @@ static int journal_get_superblock(journal_t *journal)
>  		       "at the same time!\n");
>  		goto out;
>  	}
> -
>  	if (!jbd2_verify_csum_type(journal, sb)) {
>  		printk(KERN_ERR "JBD2: Unknown checksum type\n");
>  		goto out;
>  	}
> -
>  	/* Load the checksum driver */
>  	if (jbd2_journal_has_csum_v2or3_feature(journal)) {
>  		journal->j_chksum_driver = crypto_alloc_shash("crc32c", 0, 0);

Otherwise the patch looks good.

									Honza

-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR