bcachefs: Fix insufficient disk reservation with compression + snapshots

When overwriting and splitting existing extents, we weren't correctly
accounting for a 3 way split of a compressed extent.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-12-21 21:05:07 -05:00
commit 01db5e5f2f