Re: [PATCH 01/16] xfs: factor out the CIL transaction header building

[Chandan Babu R <chandan.babu@oracle.com>]

On 19 Nov 2021 at 04:43, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> It is static code deep in the middle of the CIL push logic. Factor
> it out into a helper so that it is clear and easy to modify
> separately.
>

A straight forward abstraction of existing code into a new helper.

Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>

> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> Reviewed-by: Brian Foster <bfoster@redhat.com>
> ---
>  fs/xfs/xfs_log_cil.c | 61 ++++++++++++++++++++++++++++----------------
>  1 file changed, 39 insertions(+), 22 deletions(-)
>
> diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
> index 6c93c8ada6f3..28f8104fbef1 100644
> --- a/fs/xfs/xfs_log_cil.c
> +++ b/fs/xfs/xfs_log_cil.c
> @@ -834,6 +834,41 @@ xlog_cil_write_commit_record(
>  	return error;
>  }
>  
> +struct xlog_cil_trans_hdr {
> +	struct xfs_trans_header	thdr;
> +	struct xfs_log_iovec	lhdr;
> +};
> +
> +/*
> + * Build a checkpoint transaction header to begin the journal transaction.  We
> + * need to account for the space used by the transaction header here as it is
> + * not accounted for in xlog_write().
> + */
> +static void
> +xlog_cil_build_trans_hdr(
> +	struct xfs_cil_ctx	*ctx,
> +	struct xlog_cil_trans_hdr *hdr,
> +	struct xfs_log_vec	*lvhdr,
> +	int			num_iovecs)
> +{
> +	struct xlog_ticket	*tic = ctx->ticket;
> +
> +	memset(hdr, 0, sizeof(*hdr));
> +
> +	hdr->thdr.th_magic = XFS_TRANS_HEADER_MAGIC;
> +	hdr->thdr.th_type = XFS_TRANS_CHECKPOINT;
> +	hdr->thdr.th_tid = tic->t_tid;
> +	hdr->thdr.th_num_items = num_iovecs;
> +	hdr->lhdr.i_addr = &hdr->thdr;
> +	hdr->lhdr.i_len = sizeof(xfs_trans_header_t);
> +	hdr->lhdr.i_type = XLOG_REG_TYPE_TRANSHDR;
> +	tic->t_curr_res -= hdr->lhdr.i_len + sizeof(struct xlog_op_header);
> +
> +	lvhdr->lv_niovecs = 1;
> +	lvhdr->lv_iovecp = &hdr->lhdr;
> +	lvhdr->lv_next = ctx->lv_chain;
> +}
> +
>  /*
>   * Push the Committed Item List to the log.
>   *
> @@ -858,11 +893,9 @@ xlog_cil_push_work(
>  	struct xlog		*log = cil->xc_log;
>  	struct xfs_log_vec	*lv;
>  	struct xfs_cil_ctx	*new_ctx;
> -	struct xlog_ticket	*tic;
>  	int			num_iovecs;
>  	int			error = 0;
> -	struct xfs_trans_header thdr;
> -	struct xfs_log_iovec	lhdr;
> +	struct xlog_cil_trans_hdr thdr;
>  	struct xfs_log_vec	lvhdr = { NULL };
>  	xfs_lsn_t		preflush_tail_lsn;
>  	xfs_csn_t		push_seq;
> @@ -1011,24 +1044,8 @@ xlog_cil_push_work(
>  	 * Build a checkpoint transaction header and write it to the log to
>  	 * begin the transaction. We need to account for the space used by the
>  	 * transaction header here as it is not accounted for in xlog_write().
> -	 *
> -	 * The LSN we need to pass to the log items on transaction commit is
> -	 * the LSN reported by the first log vector write. If we use the commit
> -	 * record lsn then we can move the tail beyond the grant write head.
>  	 */
> -	tic = ctx->ticket;
> -	thdr.th_magic = XFS_TRANS_HEADER_MAGIC;
> -	thdr.th_type = XFS_TRANS_CHECKPOINT;
> -	thdr.th_tid = tic->t_tid;
> -	thdr.th_num_items = num_iovecs;
> -	lhdr.i_addr = &thdr;
> -	lhdr.i_len = sizeof(xfs_trans_header_t);
> -	lhdr.i_type = XLOG_REG_TYPE_TRANSHDR;
> -	tic->t_curr_res -= lhdr.i_len + sizeof(xlog_op_header_t);
> -
> -	lvhdr.lv_niovecs = 1;
> -	lvhdr.lv_iovecp = &lhdr;
> -	lvhdr.lv_next = ctx->lv_chain;
> +	xlog_cil_build_trans_hdr(ctx, &thdr, &lvhdr, num_iovecs);
>  
>  	/*
>  	 * Before we format and submit the first iclog, we have to ensure that
> @@ -1044,7 +1061,7 @@ xlog_cil_push_work(
>  	if (error)
>  		goto out_abort_free_ticket;
>  
> -	xfs_log_ticket_ungrant(log, tic);
> +	xfs_log_ticket_ungrant(log, ctx->ticket);
>  
>  	/*
>  	 * If the checkpoint spans multiple iclogs, wait for all previous iclogs
> @@ -1108,7 +1125,7 @@ xlog_cil_push_work(
>  	return;
>  
>  out_abort_free_ticket:
> -	xfs_log_ticket_ungrant(log, tic);
> +	xfs_log_ticket_ungrant(log, ctx->ticket);
>  	ASSERT(xlog_is_shutdown(log));
>  	if (!ctx->commit_iclog) {
>  		xlog_cil_committed(ctx);


-- 
chandan