[PATCH 38/45] xfs: convert CIL busy extents to per-cpu

[Dave Chinner <david@fromorbit.com>]

From: Dave Chinner <dchinner@redhat.com>

To get them out from under the CIL lock.

This is an unordered list, so we can simply punt it to per-cpu lists
during transaction commits and reaggregate it back into a single
list during the CIL push work.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_log_cil.c | 26 ++++++++++++++++++--------
 1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index a2f93bd7644b..7428b98c8279 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -501,6 +501,9 @@ xlog_cil_insert_items(
 		atomic_add(cilpcp->space_used, &ctx->space_used);
 		cilpcp->space_used = 0;
 	}
+	/* attach the transaction to the CIL if it has any busy extents */
+	if (!list_empty(&tp->t_busy))
+		list_splice_init(&tp->t_busy, &cilpcp->busy_extents);
 	put_cpu_ptr(cilpcp);
 
 	/*
@@ -540,9 +543,6 @@ xlog_cil_insert_items(
 			list_move_tail(&lip->li_cil, &cil->xc_cil);
 	}
 
-	/* attach the transaction to the CIL if it has any busy extents */
-	if (!list_empty(&tp->t_busy))
-		list_splice_init(&tp->t_busy, &ctx->busy_extents);
 	spin_unlock(&cil->xc_cil_lock);
 
 	if (tp->t_ticket->t_curr_res < 0)
@@ -802,7 +802,10 @@ xlog_cil_push_work(
 		ctx->ticket->t_curr_res += cilpcp->space_reserved;
 		cilpcp->space_used = 0;
 		cilpcp->space_reserved = 0;
-
+		if (!list_empty(&cilpcp->busy_extents)) {
+			list_splice_init(&cilpcp->busy_extents,
+					&ctx->busy_extents);
+		}
 	}
 
 	spin_lock(&cil->xc_push_lock);
@@ -1459,17 +1462,24 @@ static void __percpu *
 xlog_cil_pcp_alloc(
 	struct xfs_cil		*cil)
 {
+	void __percpu		*pcptr;
 	struct xlog_cil_pcp	*cilpcp;
+	int			cpu;
 
-	cilpcp = alloc_percpu(struct xlog_cil_pcp);
-	if (!cilpcp)
+	pcptr = alloc_percpu(struct xlog_cil_pcp);
+	if (!pcptr)
 		return NULL;
 
+	for_each_possible_cpu(cpu) {
+		cilpcp = per_cpu_ptr(pcptr, cpu);
+		INIT_LIST_HEAD(&cilpcp->busy_extents);
+	}
+
 	if (xlog_cil_pcp_hpadd(cil) < 0) {
-		free_percpu(cilpcp);
+		free_percpu(pcptr);
 		return NULL;
 	}
-	return cilpcp;
+	return pcptr;
 }
 
 static void
-- 
2.28.0