btrfs: stripe_alloc: relocate a queued stripe group even while it has reserved or pinned bytes
The reclaim worker defers any group that has bytes reserved or pinned,
on the theory that it was queued for falling below the used threshold
and may be about to go empty on its own. A stripe_alloc or stripe_meta
group is queued for the opposite reason -- free space trapped in
partially used stripes, which no amount of waiting frees -- and under
COW churn a metadata group has blocks reserved or pinned at every
moment, so the worker skipped every one of seven queued metadata
groups for the whole of a fill-to-the-edge test and relocated none.
Relocation already waits for in-flight allocations and writers on its
own; take the group.
projects / linux / commit