[RFC PATCH 07/17] btrfs: priority alloc: add functions to remove block group from priority tree

[Su Yue]

Introduce btrfs_remove_block_group_priority() to remove block group
from priority tree.

Signed-off-by: Su Yue <suy.f...@cn.fujitsu.com>
---
 fs/btrfs/extent-tree.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 5bae757786dc..b559c9a9afc6 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -11429,3 +11429,40 @@ static void add_block_group_priority(struct 
btrfs_block_group_cache *cache)
        up_write(&pt->groups_sem);
        BUG_ON(ret);
 }
+
+static void unlink_block_group_priority(struct btrfs_priority_tree *pt,
+                                       struct btrfs_block_group_cache *cache)
+{
+       rb_erase(&cache->node, &pt->block_groups);
+       RB_CLEAR_NODE(&cache->node);
+}
+
+void btrfs_remove_block_group_priority(struct btrfs_block_group_cache *cache)
+{
+       struct btrfs_priority_tree *pt;
+
+       if (!is_priority_alloc_enabled(cache->fs_info))
+               return;
+
+       spin_lock(&cache->lock);
+       if (cache->priority_tree == NULL) {
+               spin_unlock(&cache->lock);
+               return;
+       }
+
+       pt = cache->priority_tree;
+       cache->priority = PRIORITY_BG_DELETED;
+       spin_unlock(&cache->lock);
+
+       down_write(&pt->groups_sem);
+       spin_lock(&cache->lock);
+
+       if (cache->priority_tree == NULL)
+               goto out;
+
+       unlink_block_group_priority(pt, cache);
+       cache->priority_tree = NULL;
+out:
+       spin_unlock(&cache->lock);
+       up_write(&pt->groups_sem);
+}
-- 
2.19.1