btrfs: qgroup: use qgroup_iterator to replace tmp ulist in qgroup_update_refcnt()

For function qgroup_update_refcnt(), we use @tmp list to iterate all the
involved qgroups of a subvolume.

It's a perfect match for qgroup_iterator facility, as that @tmp ulist
has a very limited lifespan (just inside the while() loop).

By migrating to qgroup_iterator, we can get rid of the GFP_ATOMIC memory
allocation and no error handling is needed.

Reviewed-by: Boris Burkov <[email protected]>
Signed-off-by: Qu Wenruo <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

0 files changed, 0 insertions, 0 deletions