On Wed, Aug 06, 2025 at 04:56:21PM +0200, Christoph Hellwig wrote:

quoted

index 0a29b20939d17..d0ed28d40fe02 100644

--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h

@@ -264,6 +264,8 @@ struct bio {
 
 	unsigned short		bi_max_vecs;	/* max bvl_vecs we can hold */
 
+	unsigned int		page_gaps;	/* a mask of all the vector gaps */

Bloating the bio for the gaps, especially as the bio is otherwise not
built to hardware limits at all seems like an odd tradeoff.

Maybe, but I don't have anywhere else to put this. We split the bio to
its hardware limits at some point, which is where this field gets
initially set.

It doesn't need to be a mask (though that conceptually is the most
intuitive). It really just needs to indicate the lowest set bit of any
page gap between segments. There is a one byte hole in the bio that can
fit it without changing the bio size.