bcache: Improve lazy sorting

The old lazy sorting code was kind of hacky - rewrite in a way that
mathematically makes more sense; the idea is that the size of the sets
of keys in a btree node should increase by a more or less fixed ratio
from smallest to biggest.

Signed-off-by: Kent Overstreet <koverstreet@google.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index f24c2e0cbb1c..3c8474161e8e 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1375,6 +1375,8 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
 		c->btree_pages = max_t(int, c->btree_pages / 4,
 				       BTREE_MAX_PAGES);
 
+	c->sort_crit_factor = int_sqrt(c->btree_pages);
+
 	mutex_init(&c->bucket_lock);
 	mutex_init(&c->sort_lock);
 	spin_lock_init(&c->sort_time_lock);