bcachefs: bkey_ops.min_val_size

This adds a new field to bkey_ops for the minimum size of the value,
which standardizes that check and also enforces the new rule (previously
done somewhat ad-hoc) that we can extend value types by adding new
fields on to the end.

To make that work we do _not_ initialize min_val_size with sizeof,
instead we initialize it to the size of the first version of those
values.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/bcachefs/bkey_methods.h b/fs/bcachefs/bkey_methods.h
index ec4638150eae..a65756e306b0 100644
--- a/fs/bcachefs/bkey_methods.h
+++ b/fs/bcachefs/bkey_methods.h
@@ -34,6 +34,9 @@ struct bkey_ops {
 	void		(*compat)(enum btree_id id, unsigned version,
 				  unsigned big_endian, int write,
 				  struct bkey_s);
+
+	/* Size of value type when first created: */
+	unsigned	min_val_size;
 };
 
 extern const struct bkey_ops bch2_bkey_ops[];