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Mon, 01 Dec 2025 13:41:47 -0800 (PST) X-Relaying-Domain: purestorage.com Received: from dev-csander.dev.purestorage.com (unknown [IPv6:2620:125:9007:640:ffff::1199]) by c7-smtp-2023.dev.purestorage.com (Postfix) with ESMTP id 5C177340185; Mon, 1 Dec 2025 14:41:46 -0700 (MST) Received: by dev-csander.dev.purestorage.com (Postfix, from userid 1557716354) id 50CCEE41ABA; Mon, 1 Dec 2025 14:41:46 -0700 (MST) From: Caleb Sander Mateos To: Ming Lei , Jens Axboe Cc: Caleb Sander Mateos , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] ublk: allow non-blocking ctrl cmds in IO_URING_F_NONBLOCK issue Date: Mon, 1 Dec 2025 14:41:44 -0700 Message-ID: <20251201214145.3183381-1-csander@purestorage.com> X-Mailer: git-send-email 2.45.2 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Handling most of the ublksrv_ctrl_cmd opcodes require locking a mutex, so ublk_ctrl_uring_cmd() bails out with EAGAIN when called with the IO_URING_F_NONBLOCK issue flag. However, several opcodes can be handled without blocking: - UBLK_CMD_GET_QUEUE_AFFINITY - UBLK_CMD_GET_DEV_INFO - UBLK_CMD_GET_DEV_INFO2 - UBLK_U_CMD_GET_FEATURES Handle these opcodes synchronously instead of returning EAGAIN so io_uring doesn't need to issue the command via the worker thread pool. Signed-off-by: Caleb Sander Mateos Reviewed-by: Ming Lei --- drivers/block/ublk_drv.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index c2250172de4c..3d6d5f568779 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -3671,19 +3671,33 @@ static int ublk_ctrl_uring_cmd_permission(struct ub= lk_device *ub, exit: kfree(dev_path); return ret; } =20 +static bool ublk_ctrl_uring_cmd_may_sleep(u32 cmd_op) +{ + switch (_IOC_NR(cmd_op)) { + case UBLK_CMD_GET_QUEUE_AFFINITY: + case UBLK_CMD_GET_DEV_INFO: + case UBLK_CMD_GET_DEV_INFO2: + case _IOC_NR(UBLK_U_CMD_GET_FEATURES): + return false; + default: + return true; + } +} + static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) { const struct ublksrv_ctrl_cmd *header =3D io_uring_sqe_cmd(cmd->sqe); struct ublk_device *ub =3D NULL; u32 cmd_op =3D cmd->cmd_op; int ret =3D -EINVAL; =20 - if (issue_flags & IO_URING_F_NONBLOCK) + if (ublk_ctrl_uring_cmd_may_sleep(cmd_op) && + issue_flags & IO_URING_F_NONBLOCK) return -EAGAIN; =20 ublk_ctrl_cmd_dump(cmd); =20 if (!(issue_flags & IO_URING_F_SQE128)) --=20 2.45.2