[PATCH 5/6] btrfs: simplify btrfs_select_ref_head and cleanup some local variables

[Lu Fengqi <lufq.fnst@cn.fujitsu.com>]

If the return value of find_ref_head() is NULL, the only possibility is
that delayed_refs' head ref rbtree is empty. Hence, the second
find_ref_head() is pointless.

Besides, the local variables loop and start are unnecessary, just remove
them.

Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
---
 fs/btrfs/delayed-ref.c | 17 +++--------------
 1 file changed, 3 insertions(+), 14 deletions(-)

diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c
index 885581852bea..2726d2fb4bbe 100644
--- a/fs/btrfs/delayed-ref.c
+++ b/fs/btrfs/delayed-ref.c
@@ -354,20 +354,11 @@ struct btrfs_delayed_ref_head *
 btrfs_select_ref_head(struct btrfs_delayed_ref_root *delayed_refs)
 {
 	struct btrfs_delayed_ref_head *head;
-	u64 start;
-	bool loop = false;
 
 again:
-	start = delayed_refs->run_delayed_start;
-	head = find_ref_head(delayed_refs, start, 1);
-	if (!head && !loop) {
+	head = find_ref_head(delayed_refs, delayed_refs->run_delayed_start, 1);
+	if (!head) {
 		delayed_refs->run_delayed_start = 0;
-		start = 0;
-		loop = true;
-		head = find_ref_head(delayed_refs, start, 1);
-		if (!head)
-			return NULL;
-	} else if (!head && loop) {
 		return NULL;
 	}
 
@@ -376,11 +367,9 @@ btrfs_select_ref_head(struct btrfs_delayed_ref_root *delayed_refs)
 
 		node = rb_next(&head->href_node);
 		if (!node) {
-			if (loop)
+			if (delayed_refs->run_delayed_start == 0)
 				return NULL;
 			delayed_refs->run_delayed_start = 0;
-			start = 0;
-			loop = true;
 			goto again;
 		}
 		head = rb_entry(node, struct btrfs_delayed_ref_head,
-- 
2.19.1