From 80fc1e0fc61f0929fee545917127a0585dfdacf9 Mon Sep 17 00:00:00 2001
From: Qu Wenruo <quwenruo@cn.fujitsu.com>
Date: Tue, 7 Jul 2015 16:15:27 +0800
Subject: btrfs-progs: extent-tree: Introduce btrfs_free_block_group function

This function will be used to free a empty chunk.

This provides the basis for later temp chunk cleanup.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 ctree.h       |  2 ++
 extent-tree.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)

diff --git a/ctree.h b/ctree.h
index f14a7959..5550d453 100644
--- a/ctree.h
+++ b/ctree.h
@@ -2275,6 +2275,8 @@ int btrfs_record_file_extent(struct btrfs_trans_handle *trans,
 			      struct btrfs_inode_item *inode,
 			      u64 file_pos, u64 disk_bytenr,
 			      u64 num_bytes);
+int btrfs_free_block_group(struct btrfs_trans_handle *trans,
+			   struct btrfs_fs_info *fs_info, u64 bytenr, u64 len);
 /* ctree.c */
 int btrfs_comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2);
 int btrfs_del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
diff --git a/extent-tree.c b/extent-tree.c
index 07aee9e4..ac582e05 100644
--- a/extent-tree.c
+++ b/extent-tree.c
@@ -3743,6 +3743,86 @@ out:
 	return ret;
 }
 
+int btrfs_free_block_group(struct btrfs_trans_handle *trans,
+			   struct btrfs_fs_info *fs_info, u64 bytenr, u64 len)
+{
+	struct btrfs_root *extent_root = fs_info->extent_root;
+	struct btrfs_path *path;
+	struct btrfs_block_group_item *bgi;
+	struct btrfs_key key;
+	int ret = 0;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	key.objectid = bytenr;
+	key.type = BTRFS_BLOCK_GROUP_ITEM_KEY;
+	key.offset = len;
+
+	/* Double check the block group to ensure it's empty */
+	ret = btrfs_search_slot(trans, extent_root, &key, path, 0, 0);
+	if (ret > 0) {
+		ret = -ENONET;
+		goto out;
+	}
+	if (ret < 0)
+		goto out;
+
+	bgi = btrfs_item_ptr(path->nodes[0], path->slots[0],
+			     struct btrfs_block_group_item);
+	if (btrfs_disk_block_group_used(path->nodes[0], bgi)) {
+		fprintf(stderr,
+			"WARNING: block group [%llu,%llu) is not empty\n",
+			bytenr, bytenr + len);
+		ret = -EINVAL;
+		goto out;
+	}
+	btrfs_release_path(path);
+
+	/*
+	 * Now pin all space in the block group, to prevent further transaction
+	 * allocate space from it.
+	 * Every operation needs a transaction must be in the range.
+	 */
+	btrfs_pin_extent(fs_info, bytenr, len);
+
+	/* delete block group item and chunk item */
+	ret = free_block_group_item(trans, fs_info, bytenr, len);
+	if (ret < 0) {
+		fprintf(stderr,
+			"failed to free block group item for [%llu,%llu)\n",
+			bytenr, bytenr + len);
+		btrfs_unpin_extent(fs_info, bytenr, len);
+		goto out;
+	}
+
+	ret = free_chunk_dev_extent_items(trans, fs_info, bytenr);
+	if (ret < 0) {
+		fprintf(stderr,
+			"failed to dev extents belongs to [%llu,%llu)\n",
+			bytenr, bytenr + len);
+		btrfs_unpin_extent(fs_info, bytenr, len);
+		goto out;
+	}
+	ret = free_chunk_item(trans, fs_info, bytenr, len);
+	if (ret < 0) {
+		fprintf(stderr,
+			"failed to free chunk for [%llu,%llu)\n",
+			bytenr, bytenr + len);
+		btrfs_unpin_extent(fs_info, bytenr, len);
+		goto out;
+	}
+
+	/* Now release the block_group_cache */
+	ret = free_block_group_cache(trans, fs_info, bytenr, len);
+	btrfs_unpin_extent(fs_info, bytenr, len);
+
+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.
-- 
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