On 4/14/23 22:48, Jens Axboe wrote: > 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_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@xxxxxxxxx> > --- > block/bdev.c | 1 + > block/blk-core.c | 8 ++++---- > block/genhd.c | 4 ++++ > include/linux/blk_types.h | 1 + > 4 files changed, 10 insertions(+), 4 deletions(-) > > diff --git a/block/bdev.c b/block/bdev.c > index 1795c7d4b99e..31a5d25b2b44 100644 > --- a/block/bdev.c > +++ b/block/bdev.c > @@ -419,6 +419,7 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno) > bdev->bd_inode = inode; > bdev->bd_queue = disk->queue; > bdev->bd_stats = alloc_percpu(struct disk_stats); > + bdev->bd_submit_bio = 0; "= false;" would be better to match bd_submit_bio type. [...] > diff --git a/block/genhd.c b/block/genhd.c > index 02d9cfb9e077..07736c5db988 100644 > --- a/block/genhd.c > +++ b/block/genhd.c > @@ -420,6 +420,10 @@ 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 */ > + if (disk->fops->submit_bio) > + disk->part0->bd_submit_bio = 1; "= true;" would be better to match the type. Note that this could also be: disk->part0->bd_submit_bio = disk->fops->submit_bio; thus removing the if.
