xfs: pass a CIL context to xlog_write()

Pass the CIL context to xlog_write() rather than a pointer to a LSN
variable. Only the CIL checkpoint calls to xlog_write() need to know
about the start LSN of the writes, so rework xlog_write to directly
write the LSNs into the CIL context structure.

This removes the commit_lsn variable from xlog_cil_push_work(), so
now we only have to issue the commit record ordering wakeup from
there.

Signed-off-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/xfs_log.c

@@ -871,7 +871,7 @@ xlog_write_unmount_record(
 	 */
 	if (log->l_targ != log->l_mp->m_ddev_targp)
 		blkdev_issue_flush(log->l_targ->bt_bdev);
-	return xlog_write(log, &lv_chain, ticket, NULL, NULL, reg.i_len);
+	return xlog_write(log, NULL, &lv_chain, ticket, NULL, reg.i_len);
 }
 
 /*
@@ -2383,9 +2383,9 @@ xlog_write_partial(
 int
 xlog_write(
 	struct xlog		*log,
+	struct xfs_cil_ctx	*ctx,
 	struct list_head	*lv_chain,
 	struct xlog_ticket	*ticket,
-	xfs_lsn_t		*start_lsn,
 	struct xlog_in_core	**commit_iclog,
 	uint32_t		len)
 {
@@ -2408,9 +2408,21 @@ xlog_write(
 	if (error)
 		return error;
 
-	/* start_lsn is the LSN of the first iclog written to. */
-	if (start_lsn)
-		*start_lsn = be64_to_cpu(iclog->ic_header.h_lsn);
+	/*
+	 * If we have a CIL context, record the LSN of the iclog we were just
+	 * granted space to start writing into. If the context doesn't have
+	 * a start_lsn recorded, then this iclog will contain the start record
+	 * for the checkpoint. Otherwise this write contains the commit record
+	 * for the checkpoint.
+	 */
+	if (ctx) {
+		spin_lock(&ctx->cil->xc_push_lock);
+		if (!ctx->start_lsn)
+			ctx->start_lsn = be64_to_cpu(iclog->ic_header.h_lsn);
+		else
+			ctx->commit_lsn = be64_to_cpu(iclog->ic_header.h_lsn);
+		spin_unlock(&ctx->cil->xc_push_lock);
+	}
 
 	lv = list_first_entry_or_null(lv_chain, struct xfs_log_vec, lv_list);
 	while (lv) {

fs/xfs/xfs_log_cil.c

@@ -790,14 +790,13 @@ xlog_cil_build_trans_hdr(
  */
 int
 xlog_cil_write_commit_record(
-	struct xlog		*log,
-	struct xlog_ticket	*ticket,
-	struct xlog_in_core	**iclog,
-	xfs_lsn_t		*lsn)
+	struct xfs_cil_ctx	*ctx,
+	struct xlog_in_core	**iclog)
 {
+	struct xlog		*log = ctx->cil->xc_log;
 	struct xlog_op_header	ophdr = {
 		.oh_clientid = XFS_TRANSACTION,
-		.oh_tid = cpu_to_be32(ticket->t_tid),
+		.oh_tid = cpu_to_be32(ctx->ticket->t_tid),
 		.oh_flags = XLOG_COMMIT_TRANS,
 	};
 	struct xfs_log_iovec reg = {
@@ -818,8 +817,8 @@ xlog_cil_write_commit_record(
 		return -EIO;
 
 	/* account for space used by record data */
-	ticket->t_curr_res -= reg.i_len;
-	error = xlog_write(log, &lv_chain, ticket, lsn, iclog, reg.i_len);
+	ctx->ticket->t_curr_res -= reg.i_len;
+	error = xlog_write(log, ctx, &lv_chain, ctx->ticket, iclog, reg.i_len);
 	if (error)
 		xfs_force_shutdown(log->l_mp, SHUTDOWN_LOG_IO_ERROR);
 	return error;
@@ -1038,7 +1037,7 @@ xlog_cil_push_work(
 	 * use the commit record lsn then we can move the tail beyond the grant
 	 * write head.
 	 */
-	error = xlog_write(log, &ctx->lv_chain, ctx->ticket, &ctx->start_lsn,
+	error = xlog_write(log, ctx, &ctx->lv_chain, ctx->ticket,
 				NULL, num_bytes);
 
 	/*
@@ -1083,8 +1082,7 @@ xlog_cil_push_work(
 	}
 	spin_unlock(&cil->xc_push_lock);
 
-	error = xlog_cil_write_commit_record(log, ctx->ticket, &commit_iclog,
-			&commit_lsn);
+	error = xlog_cil_write_commit_record(ctx, &commit_iclog);
 	if (error)
 		goto out_abort_free_ticket;
 
@@ -1104,7 +1102,6 @@ xlog_cil_push_work(
 	 * and wake up anyone who is waiting for the commit to complete.
 	 */
 	spin_lock(&cil->xc_push_lock);
-	ctx->commit_lsn = commit_lsn;
 	wake_up_all(&cil->xc_commit_wait);
 	spin_unlock(&cil->xc_push_lock);
 

fs/xfs/xfs_log_priv.h

@@ -487,8 +487,8 @@ xlog_write_adv_cnt(void **ptr, int *len, int *off, size_t bytes)
 
 void	xlog_print_tic_res(struct xfs_mount *mp, struct xlog_ticket *ticket);
 void	xlog_print_trans(struct xfs_trans *);
-int	xlog_write(struct xlog *log, struct list_head *lv_chain,
-		struct xlog_ticket *tic, xfs_lsn_t *start_lsn,
+int	xlog_write(struct xlog *log, struct xfs_cil_ctx *ctx,
+		struct list_head *lv_chain, struct xlog_ticket *tic,
 		struct xlog_in_core **commit_iclog, uint32_t len);
 
 void	xfs_log_ticket_ungrant(struct xlog *log, struct xlog_ticket *ticket);