linux-ext4 - Re: [PATCH v4] jbd2: avoid mount failed when commit block is partial submitted

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Message-ID: <20240620095904.65hwldqex4y4a266@quack3>
Date: Thu, 20 Jun 2024 11:59:04 +0200
From: Jan Kara <jack@...e.cz>
To: Ye Bin <yebin@...weicloud.com>
Cc: tytso@....edu, adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org,
	jack@...e.cz, Ye Bin <yebin10@...wei.com>
Subject: Re: [PATCH v4] jbd2: avoid mount failed when commit block is partial
 submitted

On Thu 20-06-24 15:24:05, Ye Bin wrote:
> From: Ye Bin <yebin10@...wei.com>
> 
> We encountered a problem that the file system could not be mounted in
> the power-off scenario. The analysis of the file system mirror shows that
> only part of the data is written to the last commit block.
> The valid data of the commit block is concentrated in the first sector.
> However, the data of the entire block is involved in the checksum calculation.
> For different hardware, the minimum atomic unit may be different.
> If the checksum of a committed block is incorrect, clear the data except the
> 'commit_header' and then calculate the checksum. If the checkusm is correct,
> it is considered that the block is partially committed, Then continue to replay
> journal.
> 
> Signed-off-by: Ye Bin <yebin10@...wei.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/jbd2/recovery.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
> index 1f7664984d6e..0d14b5f39be6 100644
> --- a/fs/jbd2/recovery.c
> +++ b/fs/jbd2/recovery.c
> @@ -443,6 +443,27 @@ static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
>  	return provided == cpu_to_be32(calculated);
>  }
>  
> +static bool jbd2_commit_block_csum_verify_partial(journal_t *j, void *buf)
> +{
> +	struct commit_header *h;
> +	__be32 provided;
> +	__u32 calculated;
> +	void *tmpbuf;
> +
> +	tmpbuf = kzalloc(j->j_blocksize, GFP_KERNEL);
> +	if (!tmpbuf)
> +		return false;
> +
> +	memcpy(tmpbuf, buf, sizeof(struct commit_header));
> +	h = tmpbuf;
> +	provided = h->h_chksum[0];
> +	h->h_chksum[0] = 0;
> +	calculated = jbd2_chksum(j, j->j_csum_seed, tmpbuf, j->j_blocksize);
> +	kfree(tmpbuf);
> +
> +	return provided == cpu_to_be32(calculated);
> +}
> +
>  static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
>  				      journal_block_tag3_t *tag3,
>  				      void *buf, __u32 sequence)
> @@ -810,6 +831,13 @@ static int do_one_pass(journal_t *journal,
>  			if (pass == PASS_SCAN &&
>  			    !jbd2_commit_block_csum_verify(journal,
>  							   bh->b_data)) {
> +				if (jbd2_commit_block_csum_verify_partial(
> +								  journal,
> +								  bh->b_data)) {
> +					pr_notice("JBD2: Find incomplete commit block in transaction %u block %lu\n",
> +						  next_commit_ID, next_log_block);
> +					goto chksum_ok;
> +				}
>  			chksum_error:
>  				if (commit_time < last_trans_commit_time)
>  					goto ignore_crc_mismatch;
> @@ -824,6 +852,7 @@ static int do_one_pass(journal_t *journal,
>  				}
>  			}
>  			if (pass == PASS_SCAN) {
> +			chksum_ok:
>  				last_trans_commit_time = commit_time;
>  				head_block = next_log_block;
>  			}
> @@ -843,6 +872,7 @@ static int do_one_pass(journal_t *journal,
>  					  next_log_block);
>  				need_check_commit_time = true;
>  			}
> +
>  			/* If we aren't in the REVOKE pass, then we can
>  			 * just skip over this block. */
>  			if (pass != PASS_REVOKE) {
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR