From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: [PATCH 03/19] block: add bio_set_polled() helper Date: Fri, 8 Feb 2019 10:34:07 -0700 Message-ID: <20190208173423.27014-4-axboe@kernel.dk> References: <20190208173423.27014-1-axboe@kernel.dk> Return-path: In-Reply-To: <20190208173423.27014-1-axboe@kernel.dk> Sender: owner-linux-aio@kvack.org To: linux-aio@kvack.org, linux-block@vger.kernel.org, linux-api@vger.kernel.org Cc: hch@lst.de, jmoyer@redhat.com, avi@scylladb.com, jannh@google.com, viro@ZenIV.linux.org.uk, Jens Axboe List-Id: linux-api@vger.kernel.org For the upcoming async polled IO, we can't sleep allocating requests. If we do, then we introduce a deadlock where the submitter already has async polled IO in-flight, but can't wait for them to complete since polled requests must be active found and reaped. Utilize the helper in the blockdev DIRECT_IO code. Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe --- fs/block_dev.c | 4 ++-- include/linux/bio.h | 14 ++++++++++++++ 2 files changed, 16 insertions(+), 2 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index f18d076a2596..392e2bfb636f 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -247,7 +247,7 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, task_io_account_write(ret); } if (iocb->ki_flags & IOCB_HIPRI) - bio.bi_opf |= REQ_HIPRI; + bio_set_polled(&bio, iocb); qc = submit_bio(&bio); for (;;) { @@ -415,7 +415,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES); if (!nr_pages) { if (iocb->ki_flags & IOCB_HIPRI) - bio->bi_opf |= REQ_HIPRI; + bio_set_polled(bio, iocb); qc = submit_bio(bio); WRITE_ONCE(iocb->ki_cookie, qc); diff --git a/include/linux/bio.h b/include/linux/bio.h index 7380b094dcca..f6f0a2b3cbc8 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -823,5 +823,19 @@ static inline int bio_integrity_add_page(struct bio *bio, struct page *page, #endif /* CONFIG_BLK_DEV_INTEGRITY */ +/* + * Mark a bio as polled. Note that for async polled IO, the caller must + * expect -EWOULDBLOCK if we cannot allocate a request (or other resources). + * We cannot block waiting for requests on polled IO, as those completions + * must be found by the caller. This is different than IRQ driven IO, where + * it's safe to wait for IO to complete. + */ +static inline void bio_set_polled(struct bio *bio, struct kiocb *kiocb) +{ + bio->bi_opf |= REQ_HIPRI; + if (!is_sync_kiocb(kiocb)) + bio->bi_opf |= REQ_NOWAIT; +} + #endif /* CONFIG_BLOCK */ #endif /* __LINUX_BIO_H */ -- 2.17.1 -- To unsubscribe, send a message with 'unsubscribe linux-aio' in the body to majordomo@kvack.org. For more info on Linux AIO, see: http://www.kvack.org/aio/ Don't email: aart@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 774AEC169C4 for ; Fri, 8 Feb 2019 17:34:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 49F072146E for ; Fri, 8 Feb 2019 17:34:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="T/2Vfyze" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727469AbfBHRel (ORCPT ); Fri, 8 Feb 2019 12:34:41 -0500 Received: from mail-it1-f195.google.com ([209.85.166.195]:36557 "EHLO mail-it1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727084AbfBHRel (ORCPT ); Fri, 8 Feb 2019 12:34:41 -0500 Received: by mail-it1-f195.google.com with SMTP id c9so10857054itj.1 for ; Fri, 08 Feb 2019 09:34:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=FBZUThjVgqlafR/VslkU6xBWVbQBqldD6jr0wVQhMXM=; b=T/2VfyzezUkUT1XKLMk3FA8NicLQsSQcupgK9kATOpDKbLaExL8NqjfmrHVKTEULa6 9SNoMI1oBtOuLzCYjmK1ZWJJ678W7zJx/NHzLanV8X/Ex/L9CPxylkls9nm8BTGI3UW/ AWIfKOcuSneFteo6wNvVWb4P669ekaKtHvu2Ayn7O2TcVvsxqpsrfhU5q/XVK1JdwWtD R1PLwYWPxgxgEwS317Khf2+MCeFHiyK7tk5eYLOVZI3+YuqzMcU8jcWCaqof/96C5/E4 lZuLYKQNo/4kytA36PdWitk1vDPmgCdOTpeO2qCVaf8ZAPig9ZypT2iVrShdxWJihyRz q1mg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=FBZUThjVgqlafR/VslkU6xBWVbQBqldD6jr0wVQhMXM=; b=fxtITzJttqLRydYT3ZmIhLHJLlIn5AgDOu4L2SO8UWOwYrcrLTU5GTYpgyL4nLfVqO rGyvyckF0L8+uzd3K7aXoyZTns1il6rHi7czA5ALj26nmjGxyE0Z8GNpzmIUJUjvSQJf V+4xUTcErdnwq5SkmDdLqSKoYruwkkGm+0xznwHGz6CjXS6oqBvOk9+BZvczbOTaponb A80HYCbTqNdjhsDH0mrcz78fuizmSTWLljKtTiD/AoSEzI+7Ew2LexDMrhcAFzwTu1YN 4KuvVlqvZF1ZcNe/Y6iWNX4PxFXKKWAD4aA+XXvLk4s6CQLz0mNvbZVBF8ZUhWyDs50p WuuQ== X-Gm-Message-State: AHQUAuYXsDr0cmGWG4c/S9yMQpgRWzbbvW5kEoOU+SaYm6ymk3kE8lqk WnwDOSVuqR2yFEHqMEWjuSxNzg== X-Google-Smtp-Source: AHgI3IYXR147umZZ5eD2vVfTVLCaGiOaEPwCGtRT3PId75Wwv8i2/JsjKLwR6exjeN6Ehmva5QDiuQ== X-Received: by 2002:a24:bd48:: with SMTP id x69mr8357291ite.81.1549647280519; Fri, 08 Feb 2019 09:34:40 -0800 (PST) Received: from localhost.localdomain ([216.160.245.98]) by smtp.gmail.com with ESMTPSA id f142sm1522627itc.15.2019.02.08.09.34.38 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 08 Feb 2019 09:34:39 -0800 (PST) From: Jens Axboe To: linux-aio@kvack.org, linux-block@vger.kernel.org, linux-api@vger.kernel.org Cc: hch@lst.de, jmoyer@redhat.com, avi@scylladb.com, jannh@google.com, viro@ZenIV.linux.org.uk, Jens Axboe Subject: [PATCH 03/19] block: add bio_set_polled() helper Date: Fri, 8 Feb 2019 10:34:07 -0700 Message-Id: <20190208173423.27014-4-axboe@kernel.dk> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190208173423.27014-1-axboe@kernel.dk> References: <20190208173423.27014-1-axboe@kernel.dk> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org For the upcoming async polled IO, we can't sleep allocating requests. If we do, then we introduce a deadlock where the submitter already has async polled IO in-flight, but can't wait for them to complete since polled requests must be active found and reaped. Utilize the helper in the blockdev DIRECT_IO code. Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe --- fs/block_dev.c | 4 ++-- include/linux/bio.h | 14 ++++++++++++++ 2 files changed, 16 insertions(+), 2 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index f18d076a2596..392e2bfb636f 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -247,7 +247,7 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, task_io_account_write(ret); } if (iocb->ki_flags & IOCB_HIPRI) - bio.bi_opf |= REQ_HIPRI; + bio_set_polled(&bio, iocb); qc = submit_bio(&bio); for (;;) { @@ -415,7 +415,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES); if (!nr_pages) { if (iocb->ki_flags & IOCB_HIPRI) - bio->bi_opf |= REQ_HIPRI; + bio_set_polled(bio, iocb); qc = submit_bio(bio); WRITE_ONCE(iocb->ki_cookie, qc); diff --git a/include/linux/bio.h b/include/linux/bio.h index 7380b094dcca..f6f0a2b3cbc8 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -823,5 +823,19 @@ static inline int bio_integrity_add_page(struct bio *bio, struct page *page, #endif /* CONFIG_BLK_DEV_INTEGRITY */ +/* + * Mark a bio as polled. Note that for async polled IO, the caller must + * expect -EWOULDBLOCK if we cannot allocate a request (or other resources). + * We cannot block waiting for requests on polled IO, as those completions + * must be found by the caller. This is different than IRQ driven IO, where + * it's safe to wait for IO to complete. + */ +static inline void bio_set_polled(struct bio *bio, struct kiocb *kiocb) +{ + bio->bi_opf |= REQ_HIPRI; + if (!is_sync_kiocb(kiocb)) + bio->bi_opf |= REQ_NOWAIT; +} + #endif /* CONFIG_BLOCK */ #endif /* __LINUX_BIO_H */ -- 2.17.1