From 5dccefd3ea0b33cf3e5a45cbccc7e0bf22791655 Mon Sep 17 00:00:00 2001
From: Coly Li <colyli@suse.de>
Date: Wed, 13 Nov 2019 16:03:22 +0800
Subject: [PATCH] bcache: add code comments in bch_btree_leaf_dirty()
Git-commit: 5dccefd3ea0b33cf3e5a45cbccc7e0bf22791655
Patch-mainline: v5.5-rc1
References: bsc#1163762

This patch adds code comments in bch_btree_leaf_dirty() to explain
why w->journal should always reference the eldest journal pin of
all the writing bkeys in the btree node. To make the bcache journal
code to be easier to be understood.

Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

---
 drivers/md/bcache/btree.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 39d7fc1ef1ee..48e33ee0d876 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -569,6 +569,11 @@ static void bch_btree_leaf_dirty(struct btree *b, atomic_t *journal_ref)
 
 	set_btree_node_dirty(b);
 
+	/*
+	 * w->journal is always the oldest journal pin of all bkeys
+	 * in the leaf node, to make sure the oldest jset seq won't
+	 * be increased before this btree node is flushed.
+	 */
 	if (journal_ref) {
 		if (w->journal &&
 		    journal_pin_cmp(b->c, w->journal, journal_ref)) {
-- 
2.16.4