From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: [PATCH 03/15] block: add bio_set_polled() helper Date: Wed, 16 Jan 2019 10:49:51 -0700 Message-ID: <20190116175003.17880-4-axboe@kernel.dk> References: <20190116175003.17880-1-axboe@kernel.dk> Cc: hch@lst.de, jmoyer@redhat.com, avi@scylladb.com, Jens Axboe To: linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-block@vger.kernel.org, linux-arch@vger.kernel.org Return-path: In-Reply-To: <20190116175003.17880-1-axboe@kernel.dk> Sender: owner-linux-aio@kvack.org List-Id: linux-fsdevel.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 -- 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=unavailable 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 6C39CC43387 for ; Wed, 16 Jan 2019 17:50:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3FBE22082F for ; Wed, 16 Jan 2019 17:50:21 +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="NCYS4jeQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727681AbfAPRuU (ORCPT ); Wed, 16 Jan 2019 12:50:20 -0500 Received: from mail-io1-f67.google.com ([209.85.166.67]:32831 "EHLO mail-io1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727676AbfAPRuS (ORCPT ); Wed, 16 Jan 2019 12:50:18 -0500 Received: by mail-io1-f67.google.com with SMTP id t24so5614076ioi.0 for ; Wed, 16 Jan 2019 09:50:18 -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=NCYS4jeQEpuNkVMkTVOVaeVrUft0DzOSAiC6fPj+l7Elh+qbwuW4SG0d829ZrFl2T8 tUGsystAt42gHhf6WMpSBh/N1Gq0QmmUWyEghWDh5H6iSw+BVFaAJltGjaCCwkjNslAl terDh5WemhixHnHHKFZxgRYDvGKXesLk/EK0XIKSm+1/636ACikDRNQUgf7trT7m3Rnl s0Ukp1dhfGdLA77UzN7p/qxHMYc3E1cwAmnBFO0O7k38E9/YBIPAczybK3RkiFsPcC5h 5lU9+yQKCbUlUoWK5DivUPdUw6HYSrVHtMSbcLsAVMdQCdMeNOikjcGNhEHqFcuKD8Un pAmg== 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=27Lm/JhUsJpkymG55uhLhyMpM6M6IdPOsWlq/569Gqs=; b=cgQJ+LPYgiXOdyh3aMBOeCVzlsOynLFG8hk3JJDs4DaAUASi3fwubZ4rvoCCMYiFvY NhjppKE2FCg4ac3DhPjwO2XYpD3kbnOVmx19KxYH7Biz9w+n4vtXSwH8ebM4tOnYBMfJ EA4Fa5I21D1nYmhk/ViA6S2GKnnmaA2Q16y3tLna8EwNN1VFXpM5/Pv0slAlkaPxUMie BAtcgVDhJLnKO7vrXnRcQnuAN4QepL3XudwQNv/2hNncfbNhfRSyl1iSf+7A9PPsU/qN 7ESI6xMbIhggDNa9w29Dz61sGj/LVE50j2ip/OfQ6Ll5Xowa/KCJ3aW24jcj/1DF0u+y 9Q9A== X-Gm-Message-State: AJcUuke4MedWSaZzDoSNXnLz7G2JUUWdD4e1TCh8YszCcqwOEA0tdZkb QiOansPKLIBDKhhNk4Q4HVRw1OqTwkuEmg== X-Google-Smtp-Source: ALg8bN5vowT5uuVRibpFdGHGtZ0ybEJbMXfPfCjYsoBDuffH9XZ3bguhHKkuOReyOU3rrQPrxEvtZQ== X-Received: by 2002:a6b:cc07:: with SMTP id c7mr5153023iog.136.1547661017041; Wed, 16 Jan 2019 09:50:17 -0800 (PST) Received: from x1.localdomain ([216.160.245.98]) by smtp.gmail.com with ESMTPSA id x128sm3705690itb.8.2019.01.16.09.50.15 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 16 Jan 2019 09:50:15 -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 03/15] block: add bio_set_polled() helper Date: Wed, 16 Jan 2019 10:49:51 -0700 Message-Id: <20190116175003.17880-4-axboe@kernel.dk> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190116175003.17880-1-axboe@kernel.dk> References: <20190116175003.17880-1-axboe@kernel.dk> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Message-ID: <20190116174951.kluv-WGQL90NhcMH1t-FFP0DUXfxq31lXwkRpfdFVfc@z> 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