bcachefs: Fix maximum btree node size

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

fs/bcachefs/opts.h

@@ -83,7 +83,7 @@ enum opt_type {
 	  "size",	NULL)						\
 	x(btree_node_size,		u16,				\
 	  OPT_FORMAT,							\
-	  OPT_SECTORS(1, 128),						\
+	  OPT_SECTORS(1, 512),						\
 	  BCH_SB_BTREE_NODE_SIZE,	512,				\
 	  "size",	"Btree node size, default 256k")		\
 	x(errors,			u8,				\