[RFC 1/3] nvme: skip block cgroups for passthrough commands

[Keith Busch]

From: Keith Busch <kbusch at kernel.org>

Passthrough requests don't go through the submit_bio() path, so all the
overhead of setting up the bio's cgroup is wasted cycles. Provide a path
to skip this setup.

Signed-off-by: Keith Busch <kbusch at kernel.org>
---
 drivers/nvme/host/ioctl.c | 2 +-
 include/linux/bio.h       | 7 ++++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index d24ea2e051564..3804e5205b42b 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -192,7 +192,7 @@ static int nvme_map_user_request(struct request *req, u64 ubuffer,
 		goto out;
 	bio = req->bio;
 	if (bdev)
-		bio_set_dev(bio, bdev);
+		__bio_set_dev(bio, bdev);
 
 	if (bdev && meta_buffer && meta_len) {
 		meta = nvme_add_user_metadata(req, meta_buffer, meta_len,
diff --git a/include/linux/bio.h b/include/linux/bio.h
index d766be7152e15..bf003412653dc 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -509,12 +509,17 @@ static inline void bio_clone_blkg_association(struct bio *dst,
 					      struct bio *src) { }
 #endif	/* CONFIG_BLK_CGROUP */
 
-static inline void bio_set_dev(struct bio *bio, struct block_device *bdev)
+static inline void __bio_set_dev(struct bio *bio, struct block_device *bdev)
 {
 	bio_clear_flag(bio, BIO_REMAPPED);
 	if (bio->bi_bdev != bdev)
 		bio_clear_flag(bio, BIO_BPS_THROTTLED);
 	bio->bi_bdev = bdev;
+}
+
+static inline void bio_set_dev(struct bio *bio, struct block_device *bdev)
+{
+	__bio_set_dev(bio, bdev);
 	bio_associate_blkg(bio);
 }
 
-- 
2.34.1