On 4/14/23 8:43?PM, Damien Le Moal wrote: > 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. Done >> 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. I made it: disk->part0->bd_submit_bio = disk->fops->submit_bio != NULL; instead to make it explicit, I don't think that assignment would be happy otherwise. -- Jens Axboe
