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 <w...@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 <w...@suse.com>
Reviewed-by: David Sterba <dste...@suse.com>
Signed-off-by: David Sterba <dste...@suse.com>
Signed-off-by: Sasha Levin <sas...@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-...@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

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