block: store bdev->bd_disk->fops->submit_bio state in bdev
We have a long chain of memory dereferencing just to whether or not
this disk has a special submit_bio helper. As that's not necessarily
the common case, add a bd_has_submit_bio state in the bdev to avoid
traversing this memory dependency chain if we don't need to.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/genhd.c b/block/genhd.c
index 02d9cfb..cadcb47 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -420,6 +420,9 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
*/
elevator_init_mq(disk->queue);
+ /* Mark bdev as having a submit_bio, if needed */
+ disk->part0->bd_has_submit_bio = disk->fops->submit_bio != NULL;
+
/*
* If the driver provides an explicit major number it also must provide
* the number of minors numbers supported, and those will be used to
