[PATCH] bcache: insert bkeys without overlap when placeholder missed

[Liu Hua <liusdu@126.com>]

Btree spliting and garbage collection process will drop
placeholders, which may cause cache miss collision. We can
insert nonoverlapping bkeys with write lock. It is helpful
for performance.

Signed-off-by: Liu Hua <liusdu@126.com>
---
 drivers/md/bcache/extents.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/md/bcache/extents.c b/drivers/md/bcache/extents.c
index c809724e6571..cc8af08aee8d 100644
--- a/drivers/md/bcache/extents.c
+++ b/drivers/md/bcache/extents.c
@@ -329,6 +329,7 @@ static bool bch_extent_insert_fixup(struct btree_keys *b,
 
 	uint64_t old_offset;
 	unsigned int old_size, sectors_found = 0;
+	bool overlay = false;
 
 	BUG_ON(!KEY_OFFSET(insert));
 	BUG_ON(!KEY_SIZE(insert));
@@ -340,15 +341,18 @@ static bool bch_extent_insert_fixup(struct btree_keys *b,
 			break;
 
 		if (bkey_cmp(&START_KEY(k), insert) >= 0) {
-			if (KEY_SIZE(k))
-				break;
-			else
+			if (!KEY_SIZE(k))
 				continue;
+			if (replace_key && overlay == false)
+				goto out;
+			break;
 		}
 
 		if (bkey_cmp(k, &START_KEY(insert)) <= 0)
 			continue;
 
+		overlay = true;
+
 		old_offset = KEY_START(k);
 		old_size = KEY_SIZE(k);
 
-- 
2.17.1