[PATCH 03/10] bcache: avoid unncessary cache prefetch bch_btree_node_get()
From: Coly Li <hidden>
Date: 2018-08-09 07:48:44
Subsystem:
bcache (block layer cache), the rest · Maintainers:
Coly Li, Kent Overstreet, Linus Torvalds
In bch_btree_node_get() the read-in btree node will be partially prefetched into L1 cache for following bset iteration (if there is). But if the btree node read is failed, the perfetch operations will waste L1 cache space. This patch checkes whether read operation and only does cache prefetch when read I/O succeeded. Signed-off-by: Coly Li <redacted> --- drivers/md/bcache/btree.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 475008fbbaab..c19f7716df88 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c@@ -1011,6 +1011,13 @@ struct btree *bch_btree_node_get(struct cache_set *c, struct btree_op *op, BUG_ON(b->level != level); } + if (btree_node_io_error(b)) { + rw_unlock(write, b); + return ERR_PTR(-EIO); + } + + BUG_ON(!b->written); + b->parent = parent; b->accessed = 1;
@@ -1022,13 +1029,6 @@ struct btree *bch_btree_node_get(struct cache_set *c, struct btree_op *op, for (; i <= b->keys.nsets; i++) prefetch(b->keys.set[i].data); - if (btree_node_io_error(b)) { - rw_unlock(write, b); - return ERR_PTR(-EIO); - } - - BUG_ON(!b->written); - return b; }
--
2.18.0