From patchwork Thu Jul 20 18:13:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Axboe X-Patchwork-Id: 13320958 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 830FDC00528 for ; Thu, 20 Jul 2023 18:13:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231296AbjGTSNZ (ORCPT ); Thu, 20 Jul 2023 14:13:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53118 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231248AbjGTSNY (ORCPT ); Thu, 20 Jul 2023 14:13:24 -0400 Received: from mail-il1-x12b.google.com (mail-il1-x12b.google.com [IPv6:2607:f8b0:4864:20::12b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6DB45FC for ; Thu, 20 Jul 2023 11:13:23 -0700 (PDT) Received: by mail-il1-x12b.google.com with SMTP id e9e14a558f8ab-345d2b936c2so1189935ab.0 for ; Thu, 20 Jul 2023 11:13:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20221208.gappssmtp.com; s=20221208; t=1689876802; x=1690481602; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=HmtTYMUzX/gcmI/rcwUW5tKXEH+MB6XY0myuWWxnltA=; b=TtTnh3nOJsWhUQESiS/FdDhWMNHmejaFgXrPFWlYvd6yTCAia2mamY37n36yDYp3j+ IeV5CSyHNb6G7GRmuPgRn+mj/NElj3ufZYICp8wLgErFN5wEpXv94F4Xv2RqT12/3k6A Ps6WuR84Yki74moAFBoJYdiS7aJFQzWBgAyouYP72gRA1uzaPLhnb9SuSWuSizi6U40F xdXSJRE6o/dlrwmzFWkMB/tk52ZhumqRg3v3g6wGI6YyOkutH5gqEEl3SCcnYvahPcLL cBV2a/V0OzTjOyusEYhuH3iFyZ7osj9/KL5y2+7FXqivBqsbEXS9MxFnUzYiqAVorrs1 LRzQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689876802; x=1690481602; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=HmtTYMUzX/gcmI/rcwUW5tKXEH+MB6XY0myuWWxnltA=; b=Hlo/sx7FLtIdVZmeO2u8gOL0sJQCfm+cBY1NAZnsb6yJ6Bu5oPMt9B7DfnIz80crCV u2aoScqqGQT735lqTlofEd+t1Z71PwLZKSHzhz3zHSgUScVptq+X5RX8mIwKOhF96N/n VFKqB8LNpfpJfLnGSz3ZLqKDCmXPDyBAm64bvHYTmZ3NsfoUSqacKHCj6JDaqwFWM/vR dljYtnVvu42CmwKLisy+L4uzZeNTCWm1+rn1pqufAc5xnmxEyNPlzZJrjjUBrcTfbD00 rkp2bYWspL5UDuEsUkUi4S6BvnrX1RQqL05Bk3sqtt1NJqT99xubhGYXa2BBqBY0Unc6 eBhA== X-Gm-Message-State: ABy/qLY06H1AceG5bOEh2dqC5U0VENthv9FIraNLPVbM7zObE9iXpmvf Z7ZARbQ2/MXLjb6D2MXFVpva1IhQVcNB4vKTR64= X-Google-Smtp-Source: APBJJlFouanhb4sgzuIro+mo0I/bEw0edbEnho2DR1D4kosEOE48J+ytS48l5Qf9uyCbXX2iGR+/VA== X-Received: by 2002:a05:6e02:17c8:b0:346:4eb9:9081 with SMTP id z8-20020a056e0217c800b003464eb99081mr12451833ilu.3.1689876802463; Thu, 20 Jul 2023 11:13:22 -0700 (PDT) Received: from localhost.localdomain ([96.43.243.2]) by smtp.gmail.com with ESMTPSA id v6-20020a92c6c6000000b003457e1daba8sm419171ilm.8.2023.07.20.11.13.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Jul 2023 11:13:21 -0700 (PDT) From: Jens Axboe To: io-uring@vger.kernel.org, linux-xfs@vger.kernel.org Cc: hch@lst.de, andres@anarazel.de, david@fromorbit.com, Jens Axboe Subject: [PATCH 6/8] fs: add IOCB flags related to passing back dio completions Date: Thu, 20 Jul 2023 12:13:08 -0600 Message-Id: <20230720181310.71589-7-axboe@kernel.dk> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230720181310.71589-1-axboe@kernel.dk> References: <20230720181310.71589-1-axboe@kernel.dk> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Async dio completions generally happen from hard/soft IRQ context, which means that users like iomap may need to defer some of the completion handling to a workqueue. This is less efficient than having the original issuer handle it, like we do for sync IO, and it adds latency to the completions. Add IOCB_DIO_DEFER, which the issuer can set if it is able to safely punt these completions to a safe context. If the dio handler is aware of this flag, assign a callback handler in kiocb->dio_complete and associated data io kiocb->private. The issuer will then call this handler with that data from task context. No functional changes in this patch. Signed-off-by: Jens Axboe Reviewed-by: Christoph Hellwig --- include/linux/fs.h | 34 ++++++++++++++++++++++++++++++++-- 1 file changed, 32 insertions(+), 2 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 6867512907d6..2c589418a078 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -338,6 +338,20 @@ enum rw_hint { #define IOCB_NOIO (1 << 20) /* can use bio alloc cache */ #define IOCB_ALLOC_CACHE (1 << 21) +/* + * IOCB_DIO_DEFER can be set by the iocb owner, to indicate that the + * iocb completion can be passed back to the owner for execution from a safe + * context rather than needing to be punted through a workqueue. If this + * flag is set, the completion handling may set iocb->dio_complete to a + * handler, which the issuer will then call from task context to complete + * the processing of the iocb. iocb->private should then also be set to + * the argument being passed to this handler. Note that while this provides + * a task context for the dio_complete() callback, it should only be used + * on the completion side for non-IO generating completions. It's fine to + * call blocking functions from this callback, but they should not wait for + * unrelated IO (like cache flushing, new IO generation, etc). + */ +#define IOCB_DIO_DEFER (1 << 22) /* for use in trace events */ #define TRACE_IOCB_STRINGS \ @@ -351,7 +365,8 @@ enum rw_hint { { IOCB_WRITE, "WRITE" }, \ { IOCB_WAITQ, "WAITQ" }, \ { IOCB_NOIO, "NOIO" }, \ - { IOCB_ALLOC_CACHE, "ALLOC_CACHE" } + { IOCB_ALLOC_CACHE, "ALLOC_CACHE" }, \ + { IOCB_DIO_DEFER, "DIO_DEFER" } struct kiocb { struct file *ki_filp; @@ -360,7 +375,22 @@ struct kiocb { void *private; int ki_flags; u16 ki_ioprio; /* See linux/ioprio.h */ - struct wait_page_queue *ki_waitq; /* for async buffered IO */ + union { + /* + * Only used for async buffered reads, where it denotes the + * page waitqueue associated with completing the read. Valid + * IFF IOCB_WAITQ is set. + */ + struct wait_page_queue *ki_waitq; + /* + * Can be used for O_DIRECT IO, where the completion handling + * is punted back to the issuer of the IO. May only be set + * if IOCB_DIO_DEFER is set by the issuer, and the issuer must + * then check for presence of this handler when ki_complete is + * invoked. + */ + ssize_t (*dio_complete)(void *data); + }; }; static inline bool is_sync_kiocb(struct kiocb *kiocb)