mainline inclusion from mainline-5.5-rc1 commit 5dccefd3ea0b33cf3e5a45cbccc7e0bf22791655 category: backport 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 c39a67c65620..15e71177d8e4 100644 --- a/drivers/md/bcache/btree.c +++ b/drivers/md/bcache/btree.c @@ -542,6 +542,11 @@ 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