Re: [PATCH AUTOSEL 5.11 26/44] btrfs: track qgroup released data in own variable in insert_prealloc_file_extent

Sasha Levin
2021-03-30T21:15:54Z

On Thu, Mar 25, 2021 at 01:08:02PM +0100, David Sterba wrote:
>On Thu, Mar 25, 2021 at 07:24:41AM -0400, Sasha Levin wrote:
>> From: Qu Wenruo <wqu@suse.com>
>>
>> [ Upstream commit fbf48bb0b197e6894a04c714728c952af7153bf3 ]
>>
>> There is a piece of weird code in insert_prealloc_file_extent(), which
>> looks like:
>>
>> ret = btrfs_qgroup_release_data(inode, file_offset, len);
>> if (ret < 0)
>> return ERR_PTR(ret);
>> if (trans) {
>> ret = insert_reserved_file_extent(trans, inode,
>> file_offset, &stack_fi,
>> true, ret);
>> ...
>> }
>> extent_info.is_new_extent = true;
>> extent_info.qgroup_reserved = ret;
>> ...
>>
>> Note how the variable @ret is abused here, and if anyone is adding code
>> just after btrfs_qgroup_release_data() call, it's super easy to
>> overwrite the @ret and cause tons of qgroup related bugs.
>>
>> Fix such abuse by introducing new variable @qgroup_released, so that we
>> won't reuse the existing variable @ret.
>>
>> Signed-off-by: Qu Wenruo <wqu@suse.com>
>> Reviewed-by: David Sterba <dsterba@suse.com>
>> Signed-off-by: David Sterba <dsterba@suse.com>
>> Signed-off-by: Sasha Levin <sashal@kernel.org>
>
>This patch is a preparatory work and does not make sense for backport
>standalone. Either this one plus
>https://lore.kernel.org/linux-btrfs/20210303104152.105877-2-wqu@suse.com/
>or neither. And IIRC it does not apply directly and needs some
>additional review before it can be backported to older code base, so it
>has no CC: stable tags.

I'll drop it, thanks!

--
Thanks,
Sasha