[PATCH 19/45] xfs: factor out the CIL transaction header building

[Dave Chinner <david@fromorbit.com>]

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.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_log_cil.c | 71 +++++++++++++++++++++++++++++---------------
 1 file changed, 47 insertions(+), 24 deletions(-)

diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index dfc9ef692a80..b515002e7959 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -651,6 +651,41 @@ xlog_cil_process_committed(
 	}
 }
 
+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(xlog_op_header_t);
+
+	lvhdr->lv_niovecs = 1;
+	lvhdr->lv_iovecp = &hdr->lhdr;
+	lvhdr->lv_next = ctx->lv_chain;
+}
+
 /*
  * Push the Committed Item List to the log.
  *
@@ -676,11 +711,9 @@ xlog_cil_push_work(
 	struct xfs_log_vec	*lv;
 	struct xfs_cil_ctx	*new_ctx;
 	struct xlog_in_core	*commit_iclog;
-	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		commit_lsn;
 	xfs_lsn_t		push_seq;
@@ -827,24 +860,8 @@ 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
@@ -852,7 +869,13 @@ xlog_cil_push_work(
 	 */
 	wait_for_completion(&bdev_flush);
 
-	error = xlog_write(log, &lvhdr, tic, &ctx->start_lsn, NULL,
+	/*
+	 * The LSN we need to pass to the log items on transaction commit is the
+	 * LSN reported by the first log vector write, not the commit lsn. If we
+	 * use the commit record lsn then we can move the tail beyond the grant
+	 * write head.
+	 */
+	error = xlog_write(log, &lvhdr, ctx->ticket, &ctx->start_lsn, NULL,
 				XLOG_START_TRANS);
 	if (error)
 		goto out_abort_free_ticket;
@@ -891,11 +914,11 @@ xlog_cil_push_work(
 	}
 	spin_unlock(&cil->xc_push_lock);
 
-	error = xlog_commit_record(log, tic, &commit_iclog, &commit_lsn);
+	error = xlog_commit_record(log, ctx->ticket, &commit_iclog, &commit_lsn);
 	if (error)
 		goto out_abort_free_ticket;
 
-	xfs_log_ticket_ungrant(log, tic);
+	xfs_log_ticket_ungrant(log, ctx->ticket);
 
 	spin_lock(&commit_iclog->ic_callback_lock);
 	if (commit_iclog->ic_state == XLOG_STATE_IOERROR) {
@@ -946,7 +969,7 @@ xlog_cil_push_work(
 	return;
 
 out_abort_free_ticket:
-	xfs_log_ticket_ungrant(log, tic);
+	xfs_log_ticket_ungrant(log, ctx->ticket);
 out_abort:
 	ASSERT(XLOG_FORCED_SHUTDOWN(log));
 	xlog_cil_committed(ctx);
-- 
2.28.0