From patchwork Thu Apr 20 15:40:31 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 13218931 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0E3D7C77B73 for ; Thu, 20 Apr 2023 15:42:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231302AbjDTPmf (ORCPT ); Thu, 20 Apr 2023 11:42:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40824 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232222AbjDTPmb (ORCPT ); Thu, 20 Apr 2023 11:42:31 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 892004C37 for ; Thu, 20 Apr 2023 08:41:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1682005298; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=N/Cgwu57JF97/LTaZdPvxnDm2iXnBsaYC73PgWZo1ek=; b=VLpmuqBb5IodiMLy+T7jRrfl0Nx7CLXRjMedvGHrlgb8O2XtGW111oC4TRj/1j3WFiI0LW kNff6lumrJLlL0gCnF2ebUjDQtHWCT6KbKORVIn1OX8EzPzZ2ai9p5IUCTkzzDt76ykwzl pwle5S2MYLbLtZL0gU90n49T56xd58I= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-483-vPy_447PNEW3jyQDi0_xUQ-1; Thu, 20 Apr 2023 11:41:34 -0400 X-MC-Unique: vPy_447PNEW3jyQDi0_xUQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 087F01C09064; Thu, 20 Apr 2023 15:41:34 +0000 (UTC) Received: from localhost (ovpn-8-16.pek2.redhat.com [10.72.8.16]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1B2C640C2064; Thu, 20 Apr 2023 15:41:32 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, ZiyangZhang , Ming Lei Subject: [PATCH 6/7] ublk: add read()/write() support for ublk char device Date: Thu, 20 Apr 2023 23:40:31 +0800 Message-Id: <20230420154032.1272836-7-ming.lei@redhat.com> In-Reply-To: <20230420154032.1272836-1-ming.lei@redhat.com> References: <20230420154032.1272836-1-ming.lei@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Support pread()/pwrite() on ublk char device for reading/writing request io buffer, so data copy between io request buffer and userspace buffer can be moved to ublk server from ublk driver. Then UBLK_F_NEED_GET_DATA becomes not necessary, so ublk server can allocate buffer without one extra round uring command communication for userspace to provide buffer. todo: implement .mmap() for mapping io request pages into userspace, so that big chunk IO zero copy can be supported Signed-off-by: Ming Lei --- drivers/block/ublk_drv.c | 151 ++++++++++++++++++++++++++++++++++ include/uapi/linux/ublk_cmd.h | 22 ++++- 2 files changed, 172 insertions(+), 1 deletion(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 7d21ee22e503..979b460464bc 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -206,6 +206,23 @@ static unsigned int ublks_added; /* protected by ublk_ctl_mutex */ static struct miscdevice ublk_misc; +static inline unsigned ublk_pos_to_hwq(loff_t pos) +{ + return ((pos - UBLKSRV_IO_BUF_OFFSET) >> UBLK_QID_OFF) & + UBLK_QID_BITS_MASK; +} + +static inline unsigned ublk_pos_to_buf_off(loff_t pos) +{ + return (pos - UBLKSRV_IO_BUF_OFFSET) & UBLK_IO_BUF_BITS_MASK; +} + +static inline unsigned ublk_pos_to_tag(loff_t pos) +{ + return ((pos - UBLKSRV_IO_BUF_OFFSET) >> UBLK_TAG_OFF) & + UBLK_TAG_BITS_MASK; +} + static void ublk_dev_param_basic_apply(struct ublk_device *ub) { struct request_queue *q = ub->ub_disk->queue; @@ -1306,6 +1323,36 @@ static inline void ublk_fill_io(struct ublk_io *io, struct io_uring_cmd *cmd, io->addr = buf_addr; } +static inline struct request *__ublk_check_and_get_req(struct ublk_device *ub, + struct ublk_queue *ubq, int tag, size_t offset) +{ + struct request *req; + + if (!ublk_need_req_ref(ubq)) + return NULL; + + req = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], tag); + if (!req) + return NULL; + + if (!ublk_get_req_ref(ubq, req)) + return NULL; + + if (unlikely(!blk_mq_request_started(req) || req->tag != tag)) + goto fail_put; + + if (!ublk_rq_has_data(req)) + goto fail_put; + + if (offset > blk_rq_bytes(req)) + goto fail_put; + + return req; +fail_put: + ublk_put_req_ref(ubq, req); + return NULL; +} + static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) { struct ublksrv_io_cmd *ub_cmd = (struct ublksrv_io_cmd *)cmd->cmd; @@ -1406,11 +1453,112 @@ static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) return -EIOCBQUEUED; } +static inline bool ublk_check_ubuf_dir(const struct request *req, + int ubuf_dir) +{ + /* copy ubuf to request pages */ + if (req_op(req) == REQ_OP_READ && ubuf_dir == ITER_SOURCE) + return true; + + /* copy request pages to ubuf */ + if (req_op(req) == REQ_OP_WRITE && ubuf_dir == ITER_DEST) + return true; + + return false; +} + +static struct request *ublk_check_and_get_req(struct kiocb *iocb, + struct iov_iter *iter, size_t *off, int dir) +{ + struct ublk_device *ub = iocb->ki_filp->private_data; + struct ublk_queue *ubq; + struct request *req; + size_t buf_off; + u16 tag, q_id; + + if (!ub) + return ERR_PTR(-EACCES); + + if (!user_backed_iter(iter)) + return ERR_PTR(-EACCES); + + if (ub->dev_info.state == UBLK_S_DEV_DEAD) + return ERR_PTR(-EACCES); + + tag = ublk_pos_to_tag(iocb->ki_pos); + q_id = ublk_pos_to_hwq(iocb->ki_pos); + buf_off = ublk_pos_to_buf_off(iocb->ki_pos); + + if (q_id >= ub->dev_info.nr_hw_queues) + return ERR_PTR(-EINVAL); + + ubq = ublk_get_queue(ub, q_id); + if (!ubq) + return ERR_PTR(-EINVAL); + + if (tag >= ubq->q_depth) + return ERR_PTR(-EINVAL); + + req = __ublk_check_and_get_req(ub, ubq, tag, buf_off); + if (!req) + return ERR_PTR(-EINVAL); + + if (!req->mq_hctx || !req->mq_hctx->driver_data) + goto fail; + + if (!ublk_check_ubuf_dir(req, dir)) + goto fail; + + *off = buf_off; + return req; +fail: + ublk_put_req_ref(ubq, req); + return ERR_PTR(-EACCES); +} + +static ssize_t ublk_ch_read_iter(struct kiocb *iocb, struct iov_iter *to) +{ + struct ublk_queue *ubq; + struct request *req; + size_t buf_off; + size_t ret; + + req = ublk_check_and_get_req(iocb, to, &buf_off, ITER_DEST); + if (IS_ERR(req)) + return PTR_ERR(req); + + ret = ublk_copy_user_pages(req, buf_off, to, ITER_DEST); + ubq = req->mq_hctx->driver_data; + ublk_put_req_ref(ubq, req); + + return ret; +} + +static ssize_t ublk_ch_write_iter(struct kiocb *iocb, struct iov_iter *from) +{ + struct ublk_queue *ubq; + struct request *req; + size_t buf_off; + size_t ret; + + req = ublk_check_and_get_req(iocb, from, &buf_off, ITER_SOURCE); + if (IS_ERR(req)) + return PTR_ERR(req); + + ret = ublk_copy_user_pages(req, buf_off, from, ITER_SOURCE); + ubq = req->mq_hctx->driver_data; + ublk_put_req_ref(ubq, req); + + return ret; +} + static const struct file_operations ublk_ch_fops = { .owner = THIS_MODULE, .open = ublk_ch_open, .release = ublk_ch_release, .llseek = no_llseek, + .read_iter = ublk_ch_read_iter, + .write_iter = ublk_ch_write_iter, .uring_cmd = ublk_ch_uring_cmd, .mmap = ublk_ch_mmap, }; @@ -2307,6 +2455,9 @@ static int __init ublk_init(void) { int ret; + BUILD_BUG_ON((unsigned long long)UBLKSRV_IO_BUF_OFFSET + + UBLKSRV_IO_BUF_BITS_SIZE < UBLKSRV_IO_BUF_OFFSET); + init_waitqueue_head(&ublk_idr_wq); ret = misc_register(&ublk_misc); diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h index 640bf687b94a..a20ea079ca9b 100644 --- a/include/uapi/linux/ublk_cmd.h +++ b/include/uapi/linux/ublk_cmd.h @@ -93,9 +93,29 @@ #define UBLKSRV_CMD_BUF_OFFSET 0 #define UBLKSRV_IO_BUF_OFFSET 0x80000000 -/* tag bit is 12bit, so at most 4096 IOs for each queue */ +/* tag bit is 15bit, so far limit at most 4096 IOs for each queue */ #define UBLK_MAX_QUEUE_DEPTH 4096 +/* single IO buffer max size is 32MB */ +#define UBLK_IO_BUF_OFF 0 +#define UBLK_IO_BUF_BITS 25 +#define UBLK_IO_BUF_BITS_MASK ((1ULL << UBLK_IO_BUF_BITS) - 1) + +/* so at most 32K IOs for each queue */ +#define UBLK_TAG_OFF UBLK_IO_BUF_BITS +#define UBLK_TAG_BITS 15 +#define UBLK_TAG_BITS_MASK ((1ULL << UBLK_TAG_BITS) - 1) + +/* max 4096 queues */ +#define UBLK_QID_OFF (UBLK_TAG_OFF + UBLK_TAG_BITS) +#define UBLK_QID_BITS 12 +#define UBLK_QID_BITS_MASK ((1ULL << UBLK_QID_BITS) - 1) + +#define UBLK_MAX_NR_QUEUES (1U << UBLK_QID_BITS) + +#define UBLKSRV_IO_BUF_BITS (UBLK_QID_OFF + UBLK_QID_BITS) +#define UBLKSRV_IO_BUF_BITS_SIZE (1ULL << UBLKSRV_IO_BUF_BITS) + /* * zero copy requires 4k block size, and can remap ublk driver's io * request into ublksrv's vm space