From e5ec5f4765ada9c75fb3eee93a6e72f0e50599d5 Mon Sep 17 00:00:00 2001
From: Coly Li <colyli@suse.de>
Date: Fri, 28 Jun 2019 19:59:55 +0800
Subject: [PATCH] bcache: only clear BTREE_NODE_dirty bit when it is set
Git-commit: e5ec5f4765ada9c75fb3eee93a6e72f0e50599d5
References: bsc#1140652
Patch-mainline: v5.3-rc1
In bch_btree_cache_free() and btree_node_free(), BTREE_NODE_dirty is
always set no matter btree node is dirty or not. The code looks like
this,
if (btree_node_dirty(b))
btree_complete_write(b, btree_current_write(b));
clear_bit(BTREE_NODE_dirty, &b->flags);
Indeed if btree_node_dirty(b) returns false, it means BTREE_NODE_dirty
bit is cleared, then it is unnecessary to clear the bit again.
This patch only clears BTREE_NODE_dirty when btree_node_dirty(b) is
true (the bit is set), to save a few CPU cycles.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
drivers/md/bcache/btree.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index cf38a1b031fa..88e5aa3fbb07 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -782,10 +782,10 @@ void bch_btree_cache_free(struct cache_set *c)
while (!list_empty(&c->btree_cache)) {
b = list_first_entry(&c->btree_cache, struct btree, list);
- if (btree_node_dirty(b))
+ if (btree_node_dirty(b)) {
btree_complete_write(b, btree_current_write(b));
- clear_bit(BTREE_NODE_dirty, &b->flags);
-
+ clear_bit(BTREE_NODE_dirty, &b->flags);
+ }
mca_data_free(b);
}
@@ -1073,9 +1073,10 @@ static void btree_node_free(struct btree *b)
mutex_lock(&b->write_lock);
- if (btree_node_dirty(b))
+ if (btree_node_dirty(b)) {
btree_complete_write(b, btree_current_write(b));
- clear_bit(BTREE_NODE_dirty, &b->flags);
+ clear_bit(BTREE_NODE_dirty, &b->flags);
+ }
mutex_unlock(&b->write_lock);
--
2.16.4