From 447e92274af6c7e8dcdc7921a6af238afcc87a0a Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Fri, 25 Nov 2022 16:04:42 -0500 Subject: [PATCH] bcachefs: Don't set accessed bit on btree node fill Btree nodes shouldn't have their accessed bit set when entering the btree cache by being read in from disk - this fixes linear scans thrashing the cache. Signed-off-by: Kent Overstreet --- fs/bcachefs/btree_cache.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/fs/bcachefs/btree_cache.c b/fs/bcachefs/btree_cache.c index 91ddbc7b84897..90be4c7325f7f 100644 --- a/fs/bcachefs/btree_cache.c +++ b/fs/bcachefs/btree_cache.c @@ -707,6 +707,12 @@ static noinline struct btree *bch2_btree_node_fill(struct bch_fs *c, if (IS_ERR(b)) return b; + /* + * Btree nodes read in from disk should not have the accessed bit set + * initially, so that linear scans don't thrash the cache: + */ + clear_btree_node_accessed(b); + bkey_copy(&b->key, k); if (bch2_btree_node_hash_insert(bc, b, level, btree_id)) { /* raced with another fill: */ @@ -843,6 +849,10 @@ retry: trace_and_count(c, trans_restart_btree_node_reused, trans, trace_ip, path); return ERR_PTR(btree_trans_restart(trans, BCH_ERR_transaction_restart_lock_node_reused)); } + + /* avoid atomic set bit if it's not needed: */ + if (!btree_node_accessed(b)) + set_btree_node_accessed(b); } if (unlikely(btree_node_read_in_flight(b))) { @@ -880,10 +890,6 @@ retry: prefetch(p + L1_CACHE_BYTES * 2); } - /* avoid atomic set bit if it's not needed: */ - if (!btree_node_accessed(b)) - set_btree_node_accessed(b); - if (unlikely(btree_node_read_error(b))) { six_unlock_type(&b->c.lock, lock_type); return ERR_PTR(-EIO); -- 2.30.2