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,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 C2317C282CE for ; Mon, 11 Feb 2019 19:01:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 90B10222A1 for ; Mon, 11 Feb 2019 19:01:02 +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="H4oMk2n9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733256AbfBKTBC (ORCPT ); Mon, 11 Feb 2019 14:01:02 -0500 Received: from mail-it1-f193.google.com ([209.85.166.193]:36777 "EHLO mail-it1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733034AbfBKTBB (ORCPT ); Mon, 11 Feb 2019 14:01:01 -0500 Received: by mail-it1-f193.google.com with SMTP id c9so935300itj.1 for ; Mon, 11 Feb 2019 11:01:01 -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=TZRgsZ4kd01/5hUxi2xP0/0l+SjG1tCpnsE1G+JLPfI=; b=H4oMk2n9Y3uwrP4JUnAI8ilC+iYkaG2D04CHxWxz5qtCzTUcHjYeufonFTjx/RKZXL Ww/xPSE/3bSzD0vqIYFl58ULiMQAIEvTW8mZh35LffczPc9vjaIJ+JUhxeAeiC0es19s kS7neX7MO+mWHwyc1URLLhH6zcyQPcRRfWcqKwqj2tW0Z3MIjnUoTBZjycauZyCwDeIF E3wF/FogVrprGArf/6TbbXH5KP2r1z9KZwUUxGQmArDnDH4Z7GaxmZhgPABFGCun+2Lv PS5q7eE41m6qCnr+y/707/g/uDnGS17aleu/izTQvO0/VERO9FWgGLc2eQ8Lk+1fIWd2 vd4A== 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=TZRgsZ4kd01/5hUxi2xP0/0l+SjG1tCpnsE1G+JLPfI=; b=LPw6bvFidTiNgNrwOuaDeYXDx6wjaGMdMg9Hhu6Gzmg4QXpBebIpYySMDBePVpV3eU sW+YrU7lOj9dVd1GnZaCJ6aImnSWQRZAyE3Bhs3j+e2hP+ekN80EcG4CAQTSRka6WeB5 rUuPzTXi/b7Yx5wzgMcHXEfl0AoPFCm74ZePLHYNKRZgdedlI44BjdZROM1Cu4NwxL6b SvYwCcbN4jvKHXOIv2A3cPbO5pTqeh/ocpU3dNgopDR3fsN624yXdFgEnIymKBKwHA7+ OrF6AWb5A34X88swALnCOhy61nPKNsLfNAa92ECsXr5d7XYvljfiyk3IF1pm/XZVJA3M OY3Q== X-Gm-Message-State: AHQUAubPJyzRnnFXGCpbfjDQq52x8JXtFF4239AQfKB0l9rbLbkLZplM aXqOYoTCUcHVXtAmmHkA6pArDQ== X-Google-Smtp-Source: AHgI3Ib6FVnZ96ZPjhFAWG2engWWFkXxsH/pHQLUJpyk+xd9yFJFpJrB0crn/p4wv1HhQojuoFctXg== X-Received: by 2002:a5e:c90d:: with SMTP id z13mr14041088iol.117.1549911660814; Mon, 11 Feb 2019 11:01:00 -0800 (PST) Received: from x1.localdomain ([216.160.245.98]) by smtp.gmail.com with ESMTPSA id h184sm62446ith.41.2019.02.11.11.00.59 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 11 Feb 2019 11:00:59 -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: Mon, 11 Feb 2019 12:00:33 -0700 Message-Id: <20190211190049.7888-5-axboe@kernel.dk> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190211190049.7888-1-axboe@kernel.dk> References: <20190211190049.7888-1-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: Hannes Reinecke 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