From patchwork Tue Jul 11 20:33:22 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Axboe X-Patchwork-Id: 13309365 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 B06D2C00528 for ; Tue, 11 Jul 2023 20:33:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230289AbjGKUdi (ORCPT ); Tue, 11 Jul 2023 16:33:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44824 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230257AbjGKUde (ORCPT ); Tue, 11 Jul 2023 16:33:34 -0400 Received: from mail-pf1-x42a.google.com (mail-pf1-x42a.google.com [IPv6:2607:f8b0:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 11AB11AE for ; Tue, 11 Jul 2023 13:33:34 -0700 (PDT) Received: by mail-pf1-x42a.google.com with SMTP id d2e1a72fcca58-682a5465e9eso980077b3a.1 for ; Tue, 11 Jul 2023 13:33:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20221208.gappssmtp.com; s=20221208; t=1689107613; x=1691699613; 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=8G1ATQFuI41fkL8nxWaXO/6T7p7QjpNqJTfODI4BURk=; b=ruLMvlGVd99hIimX09o4jOpO7XRLli4f19K5s0UL/kg8kU/nXFBG5TEdysN/kw2pxK L4yLcMmsezywupoQo+SWOuZCBlKvHlZwCxZOMWQiRWGZpl7qGfD06s7KXFBJXrquzx2+ 3cno7S1zlf63a6WwoyH8p/bSYzt2/Ksw2ZHyF/D7pZyw8sPTpO+5iOTYSsfbEQtEzdF/ ojN/5s5mAlbA8+DaMbIg71FzV1AiL5HnVyP5eNjCpBnXO5g0y9FqU2pzTZuxFkT60uJ9 a2Nb3VcYgOqxaTFSaZWdh4Ki154Nipci5q740nlVZTKt6PCC0BGcp5xg9oT3eOG0U2lb eV3A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689107613; x=1691699613; 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=8G1ATQFuI41fkL8nxWaXO/6T7p7QjpNqJTfODI4BURk=; b=VUDjoc9oI1QC9xJmJnS7MQszVkNwKRP1IYZokIWVq4boWl6VJKa0FLWT6wcXzCXmEY Y2o4R5X/AzOVZggw7cJrRy+gIV7hagKVDNegc6ZE3XoeXzzjmIoYn0vziScqAZzekow7 dTRfL1ozAxmedhDVlOy6lhqvyniv/UhWvmmgGbncf0jWjzYQcwrnBva2QZts8HI0oG8G BZReVDNBFCOmBz2moXzIvE0BVZGdOl39Qj14jXqOqQgqMGOjYL2GA2DyB1nWERhck0qt 7B1tfJy3HVHh4m+jpI+Cois/7uenQYgI2Cw6oZAnMAj2cQbVMDY/cMyX1leAmuoEn9eb zfcQ== X-Gm-Message-State: ABy/qLaTmQAWtv0bgXvlvXxqF0PkhyB+kyImpAo5Cb4ifYZvvvZ44ws2 BX1yVSRLR2bIYb0rPn1wmoTyJg== X-Google-Smtp-Source: APBJJlHzKXTNBJSugfp1HnJcJwK1C7ev1+Bvxj1jMKRytCnxsp6FqaxILGesdp1hHtLzGsNtRuKcPw== X-Received: by 2002:a05:6a20:3ca7:b0:11a:efaa:eb88 with SMTP id b39-20020a056a203ca700b0011aefaaeb88mr21693558pzj.3.1689107613516; Tue, 11 Jul 2023 13:33:33 -0700 (PDT) Received: from localhost.localdomain ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id fk13-20020a056a003a8d00b0067903510abbsm2108081pfb.163.2023.07.11.13.33.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 11 Jul 2023 13:33:32 -0700 (PDT) From: Jens Axboe To: io-uring@vger.kernel.org, linux-xfs@vger.kernel.org Cc: hch@lst.de, andres@anarazel.de, Jens Axboe Subject: [PATCH 2/5] fs: add IOCB flags related to passing back dio completions Date: Tue, 11 Jul 2023 14:33:22 -0600 Message-Id: <20230711203325.208957-3-axboe@kernel.dk> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230711203325.208957-1-axboe@kernel.dk> References: <20230711203325.208957-1-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_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 --- include/linux/fs.h | 30 ++++++++++++++++++++++++++++-- 1 file changed, 28 insertions(+), 2 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 6867512907d6..115382f66d79 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -338,6 +338,16 @@ 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. + */ +#define IOCB_DIO_DEFER (1 << 22) /* for use in trace events */ #define TRACE_IOCB_STRINGS \ @@ -351,7 +361,8 @@ 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 +371,22 @@ 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)