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@xxxxxxx>
---
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
