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=-9.1 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 1C39BC43387 for ; Tue, 8 Jan 2019 16:57:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DFA74214C6 for ; Tue, 8 Jan 2019 16:57:03 +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="m4N8NbAR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729110AbfAHQ5A (ORCPT ); Tue, 8 Jan 2019 11:57:00 -0500 Received: from mail-it1-f195.google.com ([209.85.166.195]:33132 "EHLO mail-it1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729061AbfAHQ47 (ORCPT ); Tue, 8 Jan 2019 11:56:59 -0500 Received: by mail-it1-f195.google.com with SMTP id m8so10453560itk.0 for ; Tue, 08 Jan 2019 08:56:58 -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=27Lm/JhUsJpkymG55uhLhyMpM6M6IdPOsWlq/569Gqs=; b=m4N8NbARBmEwjUvDpzAXBUWrau2jEhutC5ECDj8VGmEbtQpJvzj35KpKuVpYHFQ2Rl dsY3c3D1wr2PT5wYDpdF/Gw7YVXxn0Jj7/325gbgSzsXNH6KpcGHKPYUXMeYazv8fecc dQTCTWAS/zK9AMa032Li31lC2wzb/pADJz5Xzw13r9PKEHuCSkm//p06YPi2A6j5PMNW Jba7LXfjj0oZEnJDfhyT/ZRWJqVlcZvAUL5aK4UEewbWsaF/RLCDZgUJ5d5600VQtjMk wd2LeWfP5BhMsGbztssjp8CE1ZBuMSIybpNrpUxWe7Vhljd8JTQJ5AcAzFFdgvzHH2xX amOw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=27Lm/JhUsJpkymG55uhLhyMpM6M6IdPOsWlq/569Gqs=; b=E/QSUgf0JidtixFW0sdMoIvtfp+OOnPwh13fDriA6NKEbjOFBMLb5a0owsPw9LmAzz a0hQJphIiNM+XQSNPjWKBInzgv4Y5f6GDWNLRHpvmXsjG/4d1NPqhg2tducgKwlotNkb phP2jyUgpf1UnGaVeIGy9T3nyQQG4xgdQBJc8ksfS4FkP2dJ07GLc5gtDslZUKd+Z76C nDQfZKMaQcXoobTOThBRginoAxMj5trnTbk5cNj+NGAZuYKcwdnsC89O52JSvtNUHTgW xs0Jtfjs3ymI3j5Fg348u4gMXPmP/qcFPq1oj/QkygCRh8khloGe5AzTAFqn8MX4DsoG nhsA== X-Gm-Message-State: AJcUukeV7xg32dRCyz4yf9amupGYI+j9HsbR8rDAMgoEqMEmcv93bngY tx1dbUwB2jK5TQ0D63yho/xHDw== X-Google-Smtp-Source: ALg8bN6TPENNxihDWK16Dxc8BFhdm+oMKGCX3xZYLJa6OFE2je4LJDm652HDumCWUla6DzRFA/vpPQ== X-Received: by 2002:a24:411d:: with SMTP id x29mr1443879ita.0.1546966618374; Tue, 08 Jan 2019 08:56:58 -0800 (PST) Received: from localhost.localdomain ([216.160.245.98]) by smtp.gmail.com with ESMTPSA id m10sm17563442ioq.25.2019.01.08.08.56.56 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 08 Jan 2019 08:56:57 -0800 (PST) From: Jens Axboe To: linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-block@vger.kernel.org, linux-arch@vger.kernel.org Cc: hch@lst.de, jmoyer@redhat.com, avi@scylladb.com, Jens Axboe Subject: [PATCH 03/16] block: add bio_set_polled() helper Date: Tue, 8 Jan 2019 09:56:32 -0700 Message-Id: <20190108165645.19311-4-axboe@kernel.dk> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190108165645.19311-1-axboe@kernel.dk> References: <20190108165645.19311-1-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. 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 5415579f3e14..2ebd2a0d7789 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -233,7 +233,7 @@ __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 (;;) { @@ -401,7 +401,7 @@ __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