btrfs: add a alloc_reserved_extent helper

We duplicate this logic for both data and metadata, at this point we've
already done our type specific extent root operations, this is just
doing the accounting and removing the space from the free space tree.
Extract this common logic out into a helper.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent-tree.c

@@ -4604,6 +4604,28 @@ int btrfs_pin_reserved_extent(struct btrfs_trans_handle *trans, u64 start,
 	return ret;
 }
 
+static int alloc_reserved_extent(struct btrfs_trans_handle *trans, u64 bytenr,
+				 u64 num_bytes)
+{
+	struct btrfs_fs_info *fs_info = trans->fs_info;
+	int ret;
+
+	ret = remove_from_free_space_tree(trans, bytenr, num_bytes);
+	if (ret)
+		return ret;
+
+	ret = btrfs_update_block_group(trans, bytenr, num_bytes, true);
+	if (ret) {
+		ASSERT(!ret);
+		btrfs_err(fs_info, "update block group failed for %llu %llu",
+			  bytenr, num_bytes);
+		return ret;
+	}
+
+	trace_btrfs_reserved_extent_alloc(fs_info, bytenr, num_bytes);
+	return 0;
+}
+
 static int alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
 				      u64 parent, u64 root_objectid,
 				      u64 flags, u64 owner, u64 offset,
@@ -4664,18 +4686,7 @@ static int alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
 	btrfs_mark_buffer_dirty(path->nodes[0]);
 	btrfs_free_path(path);
 
-	ret = remove_from_free_space_tree(trans, ins->objectid, ins->offset);
-	if (ret)
-		return ret;
-
-	ret = btrfs_update_block_group(trans, ins->objectid, ins->offset, true);
-	if (ret) { /* -ENOENT, logic error */
-		btrfs_err(fs_info, "update block group failed for %llu %llu",
-			ins->objectid, ins->offset);
-		BUG();
-	}
-	trace_btrfs_reserved_extent_alloc(fs_info, ins->objectid, ins->offset);
-	return ret;
+	return alloc_reserved_extent(trans, ins->objectid, ins->offset);
 }
 
 static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
@@ -4693,7 +4704,6 @@ static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
 	struct extent_buffer *leaf;
 	struct btrfs_delayed_tree_ref *ref;
 	u32 size = sizeof(*extent_item) + sizeof(*iref);
-	u64 num_bytes;
 	u64 flags = extent_op->flags_to_set;
 	bool skinny_metadata = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
 
@@ -4703,12 +4713,10 @@ static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
 	if (skinny_metadata) {
 		extent_key.offset = ref->level;
 		extent_key.type = BTRFS_METADATA_ITEM_KEY;
-		num_bytes = fs_info->nodesize;
 	} else {
 		extent_key.offset = node->num_bytes;
 		extent_key.type = BTRFS_EXTENT_ITEM_KEY;
 		size += sizeof(*block_info);
-		num_bytes = node->num_bytes;
 	}
 
 	path = btrfs_alloc_path();
@@ -4753,23 +4761,7 @@ static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
 	btrfs_mark_buffer_dirty(leaf);
 	btrfs_free_path(path);
 
-	ret = remove_from_free_space_tree(trans, extent_key.objectid,
-					  num_bytes);
-	if (ret)
-		return ret;
-
-	ret = btrfs_update_block_group(trans, extent_key.objectid,
-				       fs_info->nodesize, true);
-	if (ret) { /* -ENOENT, logic error */
-		ASSERT(!ret);
-		btrfs_err(fs_info, "update block group failed for %llu %llu",
-			extent_key.objectid, extent_key.offset);
-		return ret;
-	}
-
-	trace_btrfs_reserved_extent_alloc(fs_info, extent_key.objectid,
-					  fs_info->nodesize);
-	return ret;
+	return alloc_reserved_extent(trans, node->bytenr, fs_info->nodesize);
 }
 
 int btrfs_alloc_reserved_file_extent(struct btrfs_trans_handle *trans,