bcachefs: Fix bkey format calculation

For extents, we increase the number of bits of the size field to allow
extents to get bigger due to merging - but this code didn't check for
overflow.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-08-13 19:34:02 -04:00
commit 029b85fe41