btrfs-progs: extent-tree: Introduce free_block_group_item function

This function is used to free a block group item.  It must be called
with all the space in the block group pinned.  Or there is a possibility
that tree blocks be allocated into the range.

The function is used for later block group/chunk free function.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/extent-tree.c b/extent-tree.c
index c24af6a..d002a4f 100644 (file)
--- a/extent-tree.c
+++ b/extent-tree.c
@@ -3448,6 +3448,42 @@ int btrfs_update_block_group(struct btrfs_trans_handle *trans,
 }
 
 /*
+ * Just remove a block group item in extent tree
+ * Caller should ensure the block group is empty and all space is pinned.
+ * Or new tree block/data may be allocated into it.
+ */
+static int free_block_group_item(struct btrfs_trans_handle *trans,
+                                struct btrfs_fs_info *fs_info,
+                                u64 bytenr, u64 len)
+{
+       struct btrfs_path *path;
+       struct btrfs_key key;
+       struct btrfs_root *root = fs_info->extent_root;
+       int ret = 0;
+
+       key.objectid = bytenr;
+       key.offset = len;
+       key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
+       if (ret > 0) {
+               ret = -ENOENT;
+               goto out;
+       }
+       if (ret < 0)
+               goto out;
+
+       ret = btrfs_del_item(trans, root, path);
+out:
+       btrfs_free_path(path);
+       return ret;
+}
+
+/*
  * Fixup block accounting. The initial block accounting created by
  * make_block_groups isn't accuracy in this case.
  */