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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>
This commit is contained in:
Jens Axboe 2023-04-14 07:32:02 -06:00
parent 3838c406a5
commit 9f4107b07b
4 changed files with 9 additions and 4 deletions
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1
block/bdev.c
View File

@ -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_has_submit_bio = false;
if (!bdev->bd_stats) {
iput(inode);
return NULL;

8
block/blk-core.c
View File

@ -587,14 +587,14 @@ static inline blk_status_t blk_check_zone_append(struct request_queue *q,
static void __submit_bio(struct bio *bio)
{
struct gendisk *disk = bio->bi_bdev->bd_disk;
if (unlikely(!blk_crypto_bio_prep(&bio)))
return;
if (!disk->fops->submit_bio) {
if (!bio->bi_bdev->bd_has_submit_bio) {
blk_mq_submit_bio(bio);
} else if (likely(bio_queue_enter(bio) == 0)) {
struct gendisk *disk = bio->bi_bdev->bd_disk;
disk->fops->submit_bio(bio);
blk_queue_exit(disk->queue);
}
@ -698,7 +698,7 @@ void submit_bio_noacct_nocheck(struct bio *bio)
*/
if (current->bio_list)
bio_list_add(&current->bio_list[0], bio);
else if (!bio->bi_bdev->bd_disk->fops->submit_bio)
else if (!bio->bi_bdev->bd_has_submit_bio)
__submit_bio_noacct_mq(bio);
else
__submit_bio_noacct(bio);

3
block/genhd.c
View File

@ -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

1
include/linux/blk_types.h
View File

@ -47,6 +47,7 @@ struct block_device {
bool bd_read_only; /* read-only policy */
u8 bd_partno;
bool bd_write_holder;
bool bd_has_submit_bio;
dev_t bd_dev;
atomic_t bd_openers;
spinlock_t bd_size_lock; /* for bd_inode->i_size updates */