Merge tag 'reserve-rt-metadata-space_2024-12-23' of https://git.kernel.org/pub/scm...

xfs: enable in-core block reservation for rt metadata [v6.2 03/14]

In preparation for adding reverse mapping and refcounting to the
realtime device, enhance the metadir code to reserve free space for
btree shape changes as delayed allocation blocks.

This enables us to pre-allocate space for the rmap and refcount btrees
in the same manner as we do for the data device counterparts, which is
how we avoid ENOSPC failures when space is low but we've already
committed to a COW operation.

This has been running on the djcloud for months with no problems.  Enjoy!

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>