From e3de04469a49ee09c89e80bf821508df458ccee6 Mon Sep 17 00:00:00 2001 From: Coly Li Date: Fri, 24 Jan 2020 01:01:42 +0800 Subject: [PATCH] bcache: reap from tail of c->btree_cache in bch_mca_scan() When shrink btree node cache from c->btree_cache in bch_mca_scan(), no matter the selected node is reaped or not, it will be rotated from the head to the tail of c->btree_cache list. But in bcache journal code, when flushing the btree nodes with oldest journal entry, btree nodes are iterated and slected from the tail of c->btree_cache list in btree_flush_write(). The list_rotate_left() in bch_mca_scan() will make btree_flush_write() iterate more nodes in c->btree_list in reverse order. This patch just reaps the selected btree node cache, and not move it from the head to the tail of c->btree_cache list. Then bch_mca_scan() will not mess up c->btree_cache list to btree_flush_write(). Signed-off-by: Coly Li Signed-off-by: Jens Axboe --- drivers/md/bcache/btree.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c index c3a314deb09d..fa872df4e770 100644 --- a/drivers/md/bcache/btree.c +++ b/drivers/md/bcache/btree.c @@ -747,19 +747,19 @@ static unsigned long bch_mca_scan(struct shrinker *shrink, i++; } - for (; (nr--) && i < btree_cache_used; i++) { - if (list_empty(&c->btree_cache)) + list_for_each_entry_safe_reverse(b, t, &c->btree_cache, list) { + if (nr <= 0 || i >= btree_cache_used) goto out; - b = list_first_entry(&c->btree_cache, struct btree, list); - list_rotate_left(&c->btree_cache); - if (!mca_reap(b, 0, false)) { mca_bucket_free(b); mca_data_free(b); rw_unlock(true, b); freed++; } + + nr--; + i++; } out: mutex_unlock(&c->bucket_lock);