From patchwork Tue Mar 7 14:15:16 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 13163677 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 59868C678D5 for ; Tue, 7 Mar 2023 14:23:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231279AbjCGOXg (ORCPT ); Tue, 7 Mar 2023 09:23:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41694 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231254AbjCGOXE (ORCPT ); Tue, 7 Mar 2023 09:23:04 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B6C6E532B0 for ; Tue, 7 Mar 2023 06:17:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1678198583; 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=Zhr1gEfDQ1b53XRiU/ym+oJgS4bMS4YfYGHBvHz+PY4=; b=HzSO2E0Lj0KnHIgBYimaTTxnLP5LrkZ+0/4BjBnUIlWbFUrOj5f2GJsjXhZUu8ZdwgTFgS Tuws8ELOowJ7dR+5hH+mU8Rn1YhDvvRSgphK1ifl5W8q7011X3act53/wkcehQAYOWWqqJ ho3L13D/4v3gL3NpW75a0/8BI22ZbPs= 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-632-KzsMQm_lPHizF4TvFWGmSw-1; Tue, 07 Mar 2023 09:16:22 -0500 X-MC-Unique: KzsMQm_lPHizF4TvFWGmSw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 130C62807D62; Tue, 7 Mar 2023 14:16:22 +0000 (UTC) Received: from localhost (ovpn-8-16.pek2.redhat.com [10.72.8.16]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2FDE01121314; Tue, 7 Mar 2023 14:16:20 +0000 (UTC) From: Ming Lei To: Jens Axboe , io-uring@vger.kernel.org Cc: linux-block@vger.kernel.org, Miklos Szeredi , ZiyangZhang , Xiaoguang Wang , Bernd Schubert , Ming Lei Subject: [PATCH V2 13/17] block: ublk_drv: grab request reference when the request is handled by userspace Date: Tue, 7 Mar 2023 22:15:16 +0800 Message-Id: <20230307141520.793891-14-ming.lei@redhat.com> In-Reply-To: <20230307141520.793891-1-ming.lei@redhat.com> References: <20230307141520.793891-1-ming.lei@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Add one reference counter into request pdu data, and hold this reference in the request's lifetime. This way is always safe. In theory, the ublk request won't be completed until fused commands are done. However, it is userspace, and application can submit fused command at will. Prepare for supporting zero copy, which needs to retrieve request buffer by fused command, so we have to guarantee: - the fused command can't succeed unless the request isn't queued - when any fused command is successful, this request can't be freed until all fused commands on this request are done. Signed-off-by: Ming Lei --- drivers/block/ublk_drv.c | 67 ++++++++++++++++++++++++++++++++++++++-- 1 file changed, 64 insertions(+), 3 deletions(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index f07eb8a54357..ba252932951c 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -43,6 +43,7 @@ #include #include #include +#include #include #define UBLK_MINORS (1U << MINORBITS) @@ -62,6 +63,17 @@ struct ublk_rq_data { struct llist_node node; struct callback_head work; + + /* + * Only for applying fused command to support zero copy: + * + * - if there is any fused command aiming at this request, not complete + * request until all fused commands are done + * + * - fused command has to fail unless this reference is grabbed + * successfully + */ + struct kref ref; }; struct ublk_uring_cmd_pdu { @@ -180,6 +192,9 @@ struct ublk_params_header { __u32 types; }; +static inline void __ublk_complete_rq(struct request *req); +static void ublk_complete_rq(struct kref *ref); + static dev_t ublk_chr_devt; static struct class *ublk_chr_class; @@ -288,6 +303,35 @@ static int ublk_apply_params(struct ublk_device *ub) return 0; } +static inline bool ublk_support_zc(const struct ublk_queue *ubq) +{ + return ubq->flags & UBLK_F_SUPPORT_ZERO_COPY; +} + +static inline bool ublk_get_req_ref(const struct ublk_queue *ubq, + struct request *req) +{ + if (ublk_support_zc(ubq)) { + struct ublk_rq_data *data = blk_mq_rq_to_pdu(req); + + return kref_get_unless_zero(&data->ref); + } + + return true; +} + +static inline void ublk_put_req_ref(const struct ublk_queue *ubq, + struct request *req) +{ + if (ublk_support_zc(ubq)) { + struct ublk_rq_data *data = blk_mq_rq_to_pdu(req); + + kref_put(&data->ref, ublk_complete_rq); + } else { + __ublk_complete_rq(req); + } +} + static inline bool ublk_can_use_task_work(const struct ublk_queue *ubq) { if (IS_BUILTIN(CONFIG_BLK_DEV_UBLK) && @@ -632,13 +676,19 @@ static inline bool ubq_daemon_is_dying(struct ublk_queue *ubq) } /* todo: handle partial completion */ -static void ublk_complete_rq(struct request *req) +static inline void __ublk_complete_rq(struct request *req) { struct ublk_queue *ubq = req->mq_hctx->driver_data; struct ublk_io *io = &ubq->ios[req->tag]; unsigned int unmapped_bytes; int res = BLK_STS_OK; + /* called from ublk_abort_queue() code path */ + if (io->flags & UBLK_IO_FLAG_ABORTED) { + res = BLK_STS_IOERR; + goto exit; + } + /* failed read IO if nothing is read */ if (!io->res && req_op(req) == REQ_OP_READ) io->res = -EIO; @@ -678,6 +728,15 @@ static void ublk_complete_rq(struct request *req) blk_mq_end_request(req, res); } +static void ublk_complete_rq(struct kref *ref) +{ + struct ublk_rq_data *data = container_of(ref, struct ublk_rq_data, + ref); + struct request *req = blk_mq_rq_from_pdu(data); + + __ublk_complete_rq(req); +} + /* * Since __ublk_rq_task_work always fails requests immediately during * exiting, __ublk_fail_req() is only called from abort context during @@ -696,7 +755,7 @@ static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io, if (ublk_queue_can_use_recovery_reissue(ubq)) blk_mq_requeue_request(req, false); else - blk_mq_end_request(req, BLK_STS_IOERR); + ublk_put_req_ref(ubq, req); } } @@ -732,6 +791,7 @@ static inline void __ublk_abort_rq(struct ublk_queue *ubq, static inline void __ublk_rq_task_work(struct request *req) { struct ublk_queue *ubq = req->mq_hctx->driver_data; + struct ublk_rq_data *data = blk_mq_rq_to_pdu(req); int tag = req->tag; struct ublk_io *io = &ubq->ios[tag]; unsigned int mapped_bytes; @@ -803,6 +863,7 @@ static inline void __ublk_rq_task_work(struct request *req) mapped_bytes >> 9; } + kref_init(&data->ref); ubq_complete_io_cmd(io, UBLK_IO_RES_OK); } @@ -1013,7 +1074,7 @@ static void ublk_commit_completion(struct ublk_device *ub, req = blk_mq_tag_to_rq(ub->tag_set.tags[qid], tag); if (req && likely(!blk_should_fake_timeout(req->q))) - ublk_complete_rq(req); + ublk_put_req_ref(ubq, req); } /*