About sbitmap_bitmap_show() and cleared bits (was Re: [PATCH RFC v7 07/12] blk-mq: Add support in hctx_tags_bitmap_show() for a shared sbitmap)

John Garry
2020-06-29T19:21:14Z

Hi all,

I noticed that sbitmap_bitmap_show() only shows set bits and does not
consider cleared bits. Is that the proper thing to do?

I ask, as from trying to support sbitmap_bitmap_show() for hostwide
shared tags feature, we currently use blk_mq_queue_tag_busy_iter() to
find active requests (and associated tags/bits) for a particular hctx.
So, AFAICT, would give a change in behavior for sbitmap_bitmap_show(),
in that it would effectively show set and not cleared bits.

Any thoughts on this?

Thanks!