On 4/26/21 9:12 PM, Changheun Lee wrote: > Actually I checked "bio->bi_disk" at first as below. It works well. Agreed that the bi_disk pointer needs to be checked. > I think "bi_bdev->bd_disk" checking might be needed too. bio_max_size() occurs in the hot path. Since if-tests have a runtime cost I'd like to keep the number of if-tests inside bio_max_size() to a minimum. I only found one bd_disk assignment in the kernel tree, namely inside bdev_alloc(). The two bdev_alloc() calls I found inside the kernel tree pass a valid disk pointer to bdev_alloc(). So I think it is not necessary to check the disk pointer inside bio_max_size(). Thanks, Bart.
