v4.19.13 snapshot.
diff --git a/fs/btrfs/tests/qgroup-tests.c b/fs/btrfs/tests/qgroup-tests.c
new file mode 100644
index 0000000..412b910
--- /dev/null
+++ b/fs/btrfs/tests/qgroup-tests.c
@@ -0,0 +1,534 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2013 Facebook.  All rights reserved.
+ */
+
+#include <linux/types.h>
+#include "btrfs-tests.h"
+#include "../ctree.h"
+#include "../transaction.h"
+#include "../disk-io.h"
+#include "../qgroup.h"
+#include "../backref.h"
+
+static int insert_normal_tree_ref(struct btrfs_root *root, u64 bytenr,
+				  u64 num_bytes, u64 parent, u64 root_objectid)
+{
+	struct btrfs_trans_handle trans;
+	struct btrfs_extent_item *item;
+	struct btrfs_extent_inline_ref *iref;
+	struct btrfs_tree_block_info *block_info;
+	struct btrfs_path *path;
+	struct extent_buffer *leaf;
+	struct btrfs_key ins;
+	u32 size = sizeof(*item) + sizeof(*iref) + sizeof(*block_info);
+	int ret;
+
+	btrfs_init_dummy_trans(&trans, NULL);
+
+	ins.objectid = bytenr;
+	ins.type = BTRFS_EXTENT_ITEM_KEY;
+	ins.offset = num_bytes;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		test_err("couldn't allocate path");
+		return -ENOMEM;
+	}
+
+	path->leave_spinning = 1;
+	ret = btrfs_insert_empty_item(&trans, root, path, &ins, size);
+	if (ret) {
+		test_err("couldn't insert ref %d", ret);
+		btrfs_free_path(path);
+		return ret;
+	}
+
+	leaf = path->nodes[0];
+	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
+	btrfs_set_extent_refs(leaf, item, 1);
+	btrfs_set_extent_generation(leaf, item, 1);
+	btrfs_set_extent_flags(leaf, item, BTRFS_EXTENT_FLAG_TREE_BLOCK);
+	block_info = (struct btrfs_tree_block_info *)(item + 1);
+	btrfs_set_tree_block_level(leaf, block_info, 0);
+	iref = (struct btrfs_extent_inline_ref *)(block_info + 1);
+	if (parent > 0) {
+		btrfs_set_extent_inline_ref_type(leaf, iref,
+						 BTRFS_SHARED_BLOCK_REF_KEY);
+		btrfs_set_extent_inline_ref_offset(leaf, iref, parent);
+	} else {
+		btrfs_set_extent_inline_ref_type(leaf, iref, BTRFS_TREE_BLOCK_REF_KEY);
+		btrfs_set_extent_inline_ref_offset(leaf, iref, root_objectid);
+	}
+	btrfs_free_path(path);
+	return 0;
+}
+
+static int add_tree_ref(struct btrfs_root *root, u64 bytenr, u64 num_bytes,
+			u64 parent, u64 root_objectid)
+{
+	struct btrfs_trans_handle trans;
+	struct btrfs_extent_item *item;
+	struct btrfs_path *path;
+	struct btrfs_key key;
+	u64 refs;
+	int ret;
+
+	btrfs_init_dummy_trans(&trans, NULL);
+
+	key.objectid = bytenr;
+	key.type = BTRFS_EXTENT_ITEM_KEY;
+	key.offset = num_bytes;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		test_err("couldn't allocate path");
+		return -ENOMEM;
+	}
+
+	path->leave_spinning = 1;
+	ret = btrfs_search_slot(&trans, root, &key, path, 0, 1);
+	if (ret) {
+		test_err("couldn't find extent ref");
+		btrfs_free_path(path);
+		return ret;
+	}
+
+	item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+			      struct btrfs_extent_item);
+	refs = btrfs_extent_refs(path->nodes[0], item);
+	btrfs_set_extent_refs(path->nodes[0], item, refs + 1);
+	btrfs_release_path(path);
+
+	key.objectid = bytenr;
+	if (parent) {
+		key.type = BTRFS_SHARED_BLOCK_REF_KEY;
+		key.offset = parent;
+	} else {
+		key.type = BTRFS_TREE_BLOCK_REF_KEY;
+		key.offset = root_objectid;
+	}
+
+	ret = btrfs_insert_empty_item(&trans, root, path, &key, 0);
+	if (ret)
+		test_err("failed to insert backref");
+	btrfs_free_path(path);
+	return ret;
+}
+
+static int remove_extent_item(struct btrfs_root *root, u64 bytenr,
+			      u64 num_bytes)
+{
+	struct btrfs_trans_handle trans;
+	struct btrfs_key key;
+	struct btrfs_path *path;
+	int ret;
+
+	btrfs_init_dummy_trans(&trans, NULL);
+
+	key.objectid = bytenr;
+	key.type = BTRFS_EXTENT_ITEM_KEY;
+	key.offset = num_bytes;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		test_err("couldn't allocate path");
+		return -ENOMEM;
+	}
+	path->leave_spinning = 1;
+
+	ret = btrfs_search_slot(&trans, root, &key, path, -1, 1);
+	if (ret) {
+		test_err("didn't find our key %d", ret);
+		btrfs_free_path(path);
+		return ret;
+	}
+	btrfs_del_item(&trans, root, path);
+	btrfs_free_path(path);
+	return 0;
+}
+
+static int remove_extent_ref(struct btrfs_root *root, u64 bytenr,
+			     u64 num_bytes, u64 parent, u64 root_objectid)
+{
+	struct btrfs_trans_handle trans;
+	struct btrfs_extent_item *item;
+	struct btrfs_path *path;
+	struct btrfs_key key;
+	u64 refs;
+	int ret;
+
+	btrfs_init_dummy_trans(&trans, NULL);
+
+	key.objectid = bytenr;
+	key.type = BTRFS_EXTENT_ITEM_KEY;
+	key.offset = num_bytes;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		test_err("couldn't allocate path");
+		return -ENOMEM;
+	}
+
+	path->leave_spinning = 1;
+	ret = btrfs_search_slot(&trans, root, &key, path, 0, 1);
+	if (ret) {
+		test_err("couldn't find extent ref");
+		btrfs_free_path(path);
+		return ret;
+	}
+
+	item = btrfs_item_ptr(path->nodes[0], path->slots[0],
+			      struct btrfs_extent_item);
+	refs = btrfs_extent_refs(path->nodes[0], item);
+	btrfs_set_extent_refs(path->nodes[0], item, refs - 1);
+	btrfs_release_path(path);
+
+	key.objectid = bytenr;
+	if (parent) {
+		key.type = BTRFS_SHARED_BLOCK_REF_KEY;
+		key.offset = parent;
+	} else {
+		key.type = BTRFS_TREE_BLOCK_REF_KEY;
+		key.offset = root_objectid;
+	}
+
+	ret = btrfs_search_slot(&trans, root, &key, path, -1, 1);
+	if (ret) {
+		test_err("couldn't find backref %d", ret);
+		btrfs_free_path(path);
+		return ret;
+	}
+	btrfs_del_item(&trans, root, path);
+	btrfs_free_path(path);
+	return ret;
+}
+
+static int test_no_shared_qgroup(struct btrfs_root *root,
+		u32 sectorsize, u32 nodesize)
+{
+	struct btrfs_trans_handle trans;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct ulist *old_roots = NULL;
+	struct ulist *new_roots = NULL;
+	int ret;
+
+	btrfs_init_dummy_trans(&trans, fs_info);
+
+	test_msg("qgroup basic add");
+	ret = btrfs_create_qgroup(&trans, BTRFS_FS_TREE_OBJECTID);
+	if (ret) {
+		test_err("couldn't create a qgroup %d", ret);
+		return ret;
+	}
+
+	/*
+	 * Since the test trans doesn't have the complicated delayed refs,
+	 * we can only call btrfs_qgroup_account_extent() directly to test
+	 * quota.
+	 */
+	ret = btrfs_find_all_roots(&trans, fs_info, nodesize, 0, &old_roots,
+			false);
+	if (ret) {
+		ulist_free(old_roots);
+		test_err("couldn't find old roots: %d", ret);
+		return ret;
+	}
+
+	ret = insert_normal_tree_ref(root, nodesize, nodesize, 0,
+				BTRFS_FS_TREE_OBJECTID);
+	if (ret)
+		return ret;
+
+	ret = btrfs_find_all_roots(&trans, fs_info, nodesize, 0, &new_roots,
+			false);
+	if (ret) {
+		ulist_free(old_roots);
+		ulist_free(new_roots);
+		test_err("couldn't find old roots: %d", ret);
+		return ret;
+	}
+
+	ret = btrfs_qgroup_account_extent(&trans, nodesize, nodesize, old_roots,
+					  new_roots);
+	if (ret) {
+		test_err("couldn't account space for a qgroup %d", ret);
+		return ret;
+	}
+
+	if (btrfs_verify_qgroup_counts(fs_info, BTRFS_FS_TREE_OBJECTID,
+				nodesize, nodesize)) {
+		test_err("qgroup counts didn't match expected values");
+		return -EINVAL;
+	}
+	old_roots = NULL;
+	new_roots = NULL;
+
+	ret = btrfs_find_all_roots(&trans, fs_info, nodesize, 0, &old_roots,
+			false);
+	if (ret) {
+		ulist_free(old_roots);
+		test_err("couldn't find old roots: %d", ret);
+		return ret;
+	}
+
+	ret = remove_extent_item(root, nodesize, nodesize);
+	if (ret)
+		return -EINVAL;
+
+	ret = btrfs_find_all_roots(&trans, fs_info, nodesize, 0, &new_roots,
+			false);
+	if (ret) {
+		ulist_free(old_roots);
+		ulist_free(new_roots);
+		test_err("couldn't find old roots: %d", ret);
+		return ret;
+	}
+
+	ret = btrfs_qgroup_account_extent(&trans, nodesize, nodesize, old_roots,
+					  new_roots);
+	if (ret) {
+		test_err("couldn't account space for a qgroup %d", ret);
+		return -EINVAL;
+	}
+
+	if (btrfs_verify_qgroup_counts(fs_info, BTRFS_FS_TREE_OBJECTID, 0, 0)) {
+		test_err("qgroup counts didn't match expected values");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * Add a ref for two different roots to make sure the shared value comes out
+ * right, also remove one of the roots and make sure the exclusive count is
+ * adjusted properly.
+ */
+static int test_multiple_refs(struct btrfs_root *root,
+		u32 sectorsize, u32 nodesize)
+{
+	struct btrfs_trans_handle trans;
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct ulist *old_roots = NULL;
+	struct ulist *new_roots = NULL;
+	int ret;
+
+	btrfs_init_dummy_trans(&trans, fs_info);
+
+	test_msg("qgroup multiple refs test");
+
+	/*
+	 * We have BTRFS_FS_TREE_OBJECTID created already from the
+	 * previous test.
+	 */
+	ret = btrfs_create_qgroup(&trans, BTRFS_FIRST_FREE_OBJECTID);
+	if (ret) {
+		test_err("couldn't create a qgroup %d", ret);
+		return ret;
+	}
+
+	ret = btrfs_find_all_roots(&trans, fs_info, nodesize, 0, &old_roots,
+			false);
+	if (ret) {
+		ulist_free(old_roots);
+		test_err("couldn't find old roots: %d", ret);
+		return ret;
+	}
+
+	ret = insert_normal_tree_ref(root, nodesize, nodesize, 0,
+				BTRFS_FS_TREE_OBJECTID);
+	if (ret)
+		return ret;
+
+	ret = btrfs_find_all_roots(&trans, fs_info, nodesize, 0, &new_roots,
+			false);
+	if (ret) {
+		ulist_free(old_roots);
+		ulist_free(new_roots);
+		test_err("couldn't find old roots: %d", ret);
+		return ret;
+	}
+
+	ret = btrfs_qgroup_account_extent(&trans, nodesize, nodesize, old_roots,
+					  new_roots);
+	if (ret) {
+		test_err("couldn't account space for a qgroup %d", ret);
+		return ret;
+	}
+
+	if (btrfs_verify_qgroup_counts(fs_info, BTRFS_FS_TREE_OBJECTID,
+				       nodesize, nodesize)) {
+		test_err("qgroup counts didn't match expected values");
+		return -EINVAL;
+	}
+
+	ret = btrfs_find_all_roots(&trans, fs_info, nodesize, 0, &old_roots,
+			false);
+	if (ret) {
+		ulist_free(old_roots);
+		test_err("couldn't find old roots: %d", ret);
+		return ret;
+	}
+
+	ret = add_tree_ref(root, nodesize, nodesize, 0,
+			BTRFS_FIRST_FREE_OBJECTID);
+	if (ret)
+		return ret;
+
+	ret = btrfs_find_all_roots(&trans, fs_info, nodesize, 0, &new_roots,
+			false);
+	if (ret) {
+		ulist_free(old_roots);
+		ulist_free(new_roots);
+		test_err("couldn't find old roots: %d", ret);
+		return ret;
+	}
+
+	ret = btrfs_qgroup_account_extent(&trans, nodesize, nodesize, old_roots,
+					  new_roots);
+	if (ret) {
+		test_err("couldn't account space for a qgroup %d", ret);
+		return ret;
+	}
+
+	if (btrfs_verify_qgroup_counts(fs_info, BTRFS_FS_TREE_OBJECTID,
+					nodesize, 0)) {
+		test_err("qgroup counts didn't match expected values");
+		return -EINVAL;
+	}
+
+	if (btrfs_verify_qgroup_counts(fs_info, BTRFS_FIRST_FREE_OBJECTID,
+					nodesize, 0)) {
+		test_err("qgroup counts didn't match expected values");
+		return -EINVAL;
+	}
+
+	ret = btrfs_find_all_roots(&trans, fs_info, nodesize, 0, &old_roots,
+			false);
+	if (ret) {
+		ulist_free(old_roots);
+		test_err("couldn't find old roots: %d", ret);
+		return ret;
+	}
+
+	ret = remove_extent_ref(root, nodesize, nodesize, 0,
+				BTRFS_FIRST_FREE_OBJECTID);
+	if (ret)
+		return ret;
+
+	ret = btrfs_find_all_roots(&trans, fs_info, nodesize, 0, &new_roots,
+			false);
+	if (ret) {
+		ulist_free(old_roots);
+		ulist_free(new_roots);
+		test_err("couldn't find old roots: %d", ret);
+		return ret;
+	}
+
+	ret = btrfs_qgroup_account_extent(&trans, nodesize, nodesize, old_roots,
+					  new_roots);
+	if (ret) {
+		test_err("couldn't account space for a qgroup %d", ret);
+		return ret;
+	}
+
+	if (btrfs_verify_qgroup_counts(fs_info, BTRFS_FIRST_FREE_OBJECTID,
+					0, 0)) {
+		test_err("qgroup counts didn't match expected values");
+		return -EINVAL;
+	}
+
+	if (btrfs_verify_qgroup_counts(fs_info, BTRFS_FS_TREE_OBJECTID,
+					nodesize, nodesize)) {
+		test_err("qgroup counts didn't match expected values");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int btrfs_test_qgroups(u32 sectorsize, u32 nodesize)
+{
+	struct btrfs_fs_info *fs_info = NULL;
+	struct btrfs_root *root;
+	struct btrfs_root *tmp_root;
+	int ret = 0;
+
+	fs_info = btrfs_alloc_dummy_fs_info(nodesize, sectorsize);
+	if (!fs_info) {
+		test_err("couldn't allocate dummy fs info");
+		return -ENOMEM;
+	}
+
+	root = btrfs_alloc_dummy_root(fs_info);
+	if (IS_ERR(root)) {
+		test_err("couldn't allocate root");
+		ret = PTR_ERR(root);
+		goto out;
+	}
+
+	/* We are using this root as our extent root */
+	root->fs_info->extent_root = root;
+
+	/*
+	 * Some of the paths we test assume we have a filled out fs_info, so we
+	 * just need to add the root in there so we don't panic.
+	 */
+	root->fs_info->tree_root = root;
+	root->fs_info->quota_root = root;
+	set_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);
+
+	/*
+	 * Can't use bytenr 0, some things freak out
+	 * *cough*backref walking code*cough*
+	 */
+	root->node = alloc_test_extent_buffer(root->fs_info, nodesize);
+	if (!root->node) {
+		test_err("couldn't allocate dummy buffer");
+		ret = -ENOMEM;
+		goto out;
+	}
+	btrfs_set_header_level(root->node, 0);
+	btrfs_set_header_nritems(root->node, 0);
+	root->alloc_bytenr += 2 * nodesize;
+
+	tmp_root = btrfs_alloc_dummy_root(fs_info);
+	if (IS_ERR(tmp_root)) {
+		test_err("couldn't allocate a fs root");
+		ret = PTR_ERR(tmp_root);
+		goto out;
+	}
+
+	tmp_root->root_key.objectid = BTRFS_FS_TREE_OBJECTID;
+	root->fs_info->fs_root = tmp_root;
+	ret = btrfs_insert_fs_root(root->fs_info, tmp_root);
+	if (ret) {
+		test_err("couldn't insert fs root %d", ret);
+		goto out;
+	}
+
+	tmp_root = btrfs_alloc_dummy_root(fs_info);
+	if (IS_ERR(tmp_root)) {
+		test_err("couldn't allocate a fs root");
+		ret = PTR_ERR(tmp_root);
+		goto out;
+	}
+
+	tmp_root->root_key.objectid = BTRFS_FIRST_FREE_OBJECTID;
+	ret = btrfs_insert_fs_root(root->fs_info, tmp_root);
+	if (ret) {
+		test_err("couldn't insert fs root %d", ret);
+		goto out;
+	}
+
+	test_msg("running qgroup tests");
+	ret = test_no_shared_qgroup(root, sectorsize, nodesize);
+	if (ret)
+		goto out;
+	ret = test_multiple_refs(root, sectorsize, nodesize);
+out:
+	btrfs_free_dummy_root(root);
+	btrfs_free_dummy_fs_info(fs_info);
+	return ret;
+}