bcache: add code comments in bch_btree_leaf_dirty()

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>
This commit is contained in:
Coly Li 2019-11-13 16:03:22 +08:00 committed by Jens Axboe
parent 84c529aea1
commit 5dccefd3ea

View File

@ -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)) {