From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: [PATCH 03/18] block: add bio_set_polled() helper Date: Mon, 28 Jan 2019 14:35:23 -0700 Message-ID: <20190128213538.13486-4-axboe@kernel.dk> References: <20190128213538.13486-1-axboe@kernel.dk> Return-path: In-Reply-To: <20190128213538.13486-1-axboe@kernel.dk> Sender: owner-linux-aio@kvack.org To: linux-aio@kvack.org, linux-block@vger.kernel.org, linux-man@vger.kernel.org, linux-api@vger.kernel.org Cc: hch@lst.de, jmoyer@redhat.com, avi@scylladb.com, 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 0F47DC282D0 for ; Mon, 28 Jan 2019 21:35:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D1DBC2177E for ; Mon, 28 Jan 2019 21:35:52 +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="1go5eIlZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728031AbfA1Vfv (ORCPT ); Mon, 28 Jan 2019 16:35:51 -0500 Received: from mail-io1-f67.google.com ([209.85.166.67]:42645 "EHLO mail-io1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726953AbfA1Vfu (ORCPT ); Mon, 28 Jan 2019 16:35:50 -0500 Received: by mail-io1-f67.google.com with SMTP id x6so14797241ioa.9 for ; Mon, 28 Jan 2019 13:35:50 -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=1go5eIlZTAt/LYcZZJlKDhBMvmSbVy6XT/R57jDUucbluf/eCRMZBGdK+j1R8iCnBG p2aoCyx2f3JT7KmccKmjUPc+ViYvLmbZCKpFUrgfngIkQYITy1RbKQXlHY7ZXUBo5yhv 8UHmrEnxgww7xPbuWVpsZOijjzlHBnI8vWX4qqcRIx9WdqtcJkp/5y2MolcSX4SjvKGj ki5xM62NHVRhVeyeCSVAxbrsR2t6nYQJqui18NrcBLXPyTWGBXjXlSKarCu9z/9gvAzP V3yW26ZPZBcWRYwiN2DDDTqjKkh/PDg8Qqj1x9efGycSVFe3AjBBi8uCiNNyZ1q+rAvx 1RVA== 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=tRu7NrJ5V7akFUiXF07RCOZ3Fw4BKVrTd0sYEbZBc+1E6+fVuLQVO0s4+aOfzSpLPe Tx+Plr0ulbb47eNOD6b1v+irapmBwHVOM7Ri931tUPiHK+nlIq4y+ImNS+KyNMAuhgvh TKDKfXfavoP4cWjj0F/gP4bNHFovvgkXbeqPs/K7z+IcggOCicjcJ//2W54zqmt2LAj2 TbagohjMjnng9ay8TxLomlxii/AhmDe6WCDb7fHtriOi8GooGczaiYO2ht8QitlWdW5m THwP8LQH1fiPpWtQDThrKp83CsRvTkzSadjRQRtje5Bc575gKSwr36jS+6sGRictMP9e hSCg== X-Gm-Message-State: AHQUAua9OwfTf+9Of/ao+rf3pXKx/+yVmel7dxAzfDULvAzdIkhrvcbp NyoAQagjABKCBeVTkyXbxMarjA== X-Google-Smtp-Source: ALg8bN5Q+XwNIP+FyNdS+6WVb0QThcIrX3Zc5SzYXChvG7+F02t7kwEFyZo3bOcTTW8WrZLpMbA9oA== X-Received: by 2002:a6b:c815:: with SMTP id y21mr12735283iof.98.1548711349997; Mon, 28 Jan 2019 13:35:49 -0800 (PST) Received: from localhost.localdomain ([216.160.245.98]) by smtp.gmail.com with ESMTPSA id u25sm13782077iob.23.2019.01.28.13.35.48 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 28 Jan 2019 13:35:49 -0800 (PST) From: Jens Axboe To: linux-aio@kvack.org, linux-block@vger.kernel.org, linux-man@vger.kernel.org, linux-api@vger.kernel.org Cc: hch@lst.de, jmoyer@redhat.com, avi@scylladb.com, Jens Axboe Subject: [PATCH 03/18] block: add bio_set_polled() helper Date: Mon, 28 Jan 2019 14:35:23 -0700 Message-Id: <20190128213538.13486-4-axboe@kernel.dk> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190128213538.13486-1-axboe@kernel.dk> References: <20190128213538.13486-1-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