Revert "btrfs: add ASSERTs on prealloc in qgroup functions"

This reverts commit 252877a.

Commit 252877a ("btrfs: add ASSERTs on prealloc in qgroup
functions") tries to remove the kfree() on preallocated qgroup during
several call sites, but this cannot work as intended:

- btrfs_quota_enable()
- btrfs_create_qgroup()
  If add_qgroup_item() failed, we go out_free_path() and at that time
  prealloc is not yet utilized and will trigger the new ASSERT().

- btrfs_qgroup_inherit()
  If qgroup_auto_inherit() failed, prealloc is not yet utilized and
  will trigger the new ASSERT()

Reported-by: syzbot+b44d4a4885bc82af2a06@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-btrfs/69369331.a70a0220.38f243.009e.GAE@google.com/
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: adam900710

fs/btrfs/qgroup.c

@@ -1243,14 +1243,7 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info,
 		btrfs_end_transaction(trans);
 	else if (trans)
 		ret = btrfs_end_transaction(trans);
-
-	/*
-	 * At this point we either failed at allocating prealloc, or we
-	 * succeeded and passed the ownership to it to add_qgroup_rb(). In any
-	 * case, this needs to be NULL or there is something wrong.
-	 */
-	ASSERT(prealloc == NULL);
-
+	kfree(prealloc);
 	return ret;
 }
 
@@ -1682,12 +1675,7 @@ int btrfs_create_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid)
 	ret = btrfs_sysfs_add_one_qgroup(fs_info, qgroup);
 out:
 	mutex_unlock(&fs_info->qgroup_ioctl_lock);
-	/*
-	 * At this point we either failed at allocating prealloc, or we
-	 * succeeded and passed the ownership to it to add_qgroup_rb(). In any
-	 * case, this needs to be NULL or there is something wrong.
-	 */
-	ASSERT(prealloc == NULL);
+	kfree(prealloc);
 	return ret;
 }
 
@@ -3279,7 +3267,7 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
 	struct btrfs_root *quota_root;
 	struct btrfs_qgroup *srcgroup;
 	struct btrfs_qgroup *dstgroup;
-	struct btrfs_qgroup *prealloc = NULL;
+	struct btrfs_qgroup *prealloc;
 	struct btrfs_qgroup_list **qlist_prealloc = NULL;
 	bool free_inherit = false;
 	bool need_rescan = false;
@@ -3520,14 +3508,7 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
 	}
 	if (free_inherit)
 		kfree(inherit);
-
-	/*
-	 * At this point we either failed at allocating prealloc, or we
-	 * succeeded and passed the ownership to it to add_qgroup_rb(). In any
-	 * case, this needs to be NULL or there is something wrong.
-	 */
-	ASSERT(prealloc == NULL);
-
+	kfree(prealloc);
 	return ret;
 }