linux-kernel - [PATCH 06/17] ublk: don't dereference ublk_queue in ublk_check_and_get

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Message-ID: <20250918014953.297897-7-csander@purestorage.com>
Date: Wed, 17 Sep 2025 19:49:42 -0600
From: Caleb Sander Mateos <csander@...estorage.com>
To: Ming Lei <ming.lei@...hat.com>,
	Jens Axboe <axboe@...nel.dk>
Cc: linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Caleb Sander Mateos <csander@...estorage.com>
Subject: [PATCH 06/17] ublk: don't dereference ublk_queue in ublk_check_and_get_req()

For ublk servers with many ublk queues, accessing the ublk_queue in
ublk_ch_{read,write}_iter() is a frequent cache miss. Get the flags and
queue depth from the ublk_device instead, which is accessed just before.

Signed-off-by: Caleb Sander Mateos <csander@...estorage.com>
---
 drivers/block/ublk_drv.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 58f688eac742..d6d8dcb72e4b 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -2525,14 +2525,14 @@ static struct request *ublk_check_and_get_req(struct kiocb *iocb,
 
 	if (q_id >= ub->dev_info.nr_hw_queues)
 		return ERR_PTR(-EINVAL);
 
 	ubq = ublk_get_queue(ub, q_id);
-	if (!ublk_support_user_copy(ubq))
+	if (!ublk_dev_support_user_copy(ub))
 		return ERR_PTR(-EACCES);
 
-	if (tag >= ubq->q_depth)
+	if (tag >= ub->dev_info.queue_depth)
 		return ERR_PTR(-EINVAL);
 
 	*io = &ubq->ios[tag];
 	req = __ublk_check_and_get_req(ub, ubq, *io, buf_off);
 	if (!req)
-- 
2.45.2