From patchwork Mon Jul 24 22:55:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Axboe X-Patchwork-Id: 13325425 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 8B1F6C001E0 for ; Mon, 24 Jul 2023 22:55:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230207AbjGXWzY (ORCPT ); Mon, 24 Jul 2023 18:55:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33504 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230073AbjGXWzX (ORCPT ); Mon, 24 Jul 2023 18:55:23 -0400 Received: from mail-pl1-x634.google.com (mail-pl1-x634.google.com [IPv6:2607:f8b0:4864:20::634]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 28ED3E49 for ; Mon, 24 Jul 2023 15:55:22 -0700 (PDT) Received: by mail-pl1-x634.google.com with SMTP id d9443c01a7336-1bbadf9ed37so1478795ad.0 for ; Mon, 24 Jul 2023 15:55:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20221208.gappssmtp.com; s=20221208; t=1690239321; x=1690844121; 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=4m73hDbmfHkB6vBAc3X7AmWd4GXS2D47NYfUBsYjTeE=; b=VG7ninWMl0JZlPdtIdNJcgkEXQh8MU+lBObbQkV5neVUmOxeTsurIAurlrNjadlfEk DbgsRETI6qP4mK3+D6R6o7o+SsqRLBHSuqTmTKPD18i6b/MNyPETV3U+eenLXgF7ot9d bviEE8LIdTNW+55BzbCtmr4SdSJmLpeCtdWBuA7RKR+K6glPgb7W5iE1csdiKxcQVqON O1Aelyg5+JUb5Yz3qcWbAqMoHKehauwOhIamUhoUOFI09lapOejJkVANZvSOrL60CYlj mOs713G+KiVtz022nbct3jHESv7OWvwynKBqfPuzycunxnsQdS2mFLpirHxtZKCx+SNn dVqA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690239321; x=1690844121; 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=4m73hDbmfHkB6vBAc3X7AmWd4GXS2D47NYfUBsYjTeE=; b=I7XNqnraYdlUqP2N080ggz1dOLkJr1D9hylrUKBgqgB2trAx+6t2HEYOEP9B75/oSJ lzqxlYjKH9fXYAKkNIHVeCQRG7E96pKB58B6UCrVVpn5Qo1E2QRJYtFgbVElDT9Yyddx 0EgjUNYAXTs/Wiuk22po8WLaix2A9/kRHvXX4hvAu+0owdLYXq75JX520PGmWbYsc81+ IQhVZwSCPr3aCF5q6CRA513BMqmlC0TBfHQvfais/SvGoHvhZ+meR3WwajngweCw6GRP crELCHZJxYycoddsy4bYayxM3InVtG+wLram1batC6XEghGuRj4qwSaHoLGOXWdPz/Za EBxQ== X-Gm-Message-State: ABy/qLaeechGR5OVRvUzR/5y/sb1sEtZONY+bi/RvYGmURv47ooEU+6i PxSu4mjxfPv9fThO8HO7VltJqh/xZppSeFKiisk= X-Google-Smtp-Source: APBJJlGVStg2IqBph0zTI/BetjM8/WiT7C7LPmmDKrWD9iKfcw4MKCaPlznHf9Vaj0ssvFl3I+fUsg== X-Received: by 2002:a17:902:d4c6:b0:1b8:85c4:48f5 with SMTP id o6-20020a170902d4c600b001b885c448f5mr15164004plg.2.1690239321659; Mon, 24 Jul 2023 15:55:21 -0700 (PDT) Received: from localhost.localdomain ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id p7-20020a1709026b8700b001acae9734c0sm9424733plk.266.2023.07.24.15.55.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Jul 2023 15:55:21 -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, djwong@kernel.org, Jens Axboe Subject: [PATCH 6/8] fs: add IOCB flags related to passing back dio completions Date: Mon, 24 Jul 2023 16:55:09 -0600 Message-Id: <20230724225511.599870-7-axboe@kernel.dk> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230724225511.599870-1-axboe@kernel.dk> References: <20230724225511.599870-1-axboe@kernel.dk> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@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_CALLER_COMP, 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. Reviewed-by: Darrick J. Wong Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe --- include/linux/fs.h | 35 +++++++++++++++++++++++++++++++++-- 1 file changed, 33 insertions(+), 2 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 6867512907d6..1e6dbe309d52 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_CALLER_COMP 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 bio completion handling may set iocb->dio_complete to a + * handler function and iocb->private to context information for that handler. + * The issuer should call the handler with that context information from task + * context to complete the processing of the iocb. 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_CALLER_COMP (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_CALLER_COMP, "CALLER_COMP" } struct kiocb { struct file *ki_filp; @@ -360,7 +375,23 @@ 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_CALLER_COMP is set by the issuer, and the issuer + * must then check for presence of this handler when ki_complete + * is invoked. The data passed in to this handler must be + * assigned to ->private when dio_complete is assigned. + */ + ssize_t (*dio_complete)(void *data); + }; }; static inline bool is_sync_kiocb(struct kiocb *kiocb)