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

[Lu Fengqi]

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.f...@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