From patchwork Thu May 11 19:17:07 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Goldwyn Rodrigues X-Patchwork-Id: 9722843 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id B7A4B60236 for ; Thu, 11 May 2017 19:18:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A72CD28700 for ; Thu, 11 May 2017 19:18:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9BA5428708; Thu, 11 May 2017 19:18:22 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F2C0A28700 for ; Thu, 11 May 2017 19:18:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934542AbdEKTRn (ORCPT ); Thu, 11 May 2017 15:17:43 -0400 Received: from mx2.suse.de ([195.135.220.15]:41835 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S934528AbdEKTRk (ORCPT ); Thu, 11 May 2017 15:17:40 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 20B38AC41; Thu, 11 May 2017 19:17:38 +0000 (UTC) From: Goldwyn Rodrigues To: linux-fsdevel@vger.kernel.org Cc: jack@suse.com, hch@infradead.org, linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, sagi@grimberg.me, avi@scylladb.com, axboe@kernel.dk, linux-api@vger.kernel.org, Goldwyn Rodrigues Subject: [PATCH 07/10] fs: return on congested block device Date: Thu, 11 May 2017 14:17:07 -0500 Message-Id: <20170511191710.31959-8-rgoldwyn@suse.de> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170511191710.31959-1-rgoldwyn@suse.de> References: <20170511191710.31959-1-rgoldwyn@suse.de> Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Goldwyn Rodrigues A new bio operation flag REQ_NOWAIT is introduced to identify bio's orignating from iocb with IOCB_NOWAIT. This flag indicates to return immediately if a request cannot be made instead of retrying. Stacked devices such as md (the ones with make_request_fn hooks) currently are not supported because it may block for housekeeping. For example, an md can have a part of the device suspended. For this reason, only request based devices are supported. In the future, this feature will be expanded to stacked devices by teaching them how to handle the REQ_NOWAIT flags. Signed-off-by: Goldwyn Rodrigues Reviewed-by: Christoph Hellwig --- block/blk-core.c | 24 ++++++++++++++++++++++-- block/blk-mq-sched.c | 3 +++ block/blk-mq.c | 4 ++++ fs/direct-io.c | 10 ++++++++-- include/linux/bio.h | 6 ++++++ include/linux/blk_types.h | 2 ++ 6 files changed, 45 insertions(+), 4 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index d772c221cc17..effe934b806b 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1232,6 +1232,11 @@ static struct request *get_request(struct request_queue *q, unsigned int op, if (!IS_ERR(rq)) return rq; + if (op & REQ_NOWAIT) { + blk_put_rl(rl); + return ERR_PTR(-EAGAIN); + } + if (!gfpflags_allow_blocking(gfp_mask) || unlikely(blk_queue_dying(q))) { blk_put_rl(rl); return rq; @@ -1870,6 +1875,17 @@ generic_make_request_checks(struct bio *bio) goto end_io; } + /* + * For a REQ_NOWAIT based request, return -EOPNOTSUPP + * if queue does not have QUEUE_FLAG_NOWAIT_SUPPORT set + * and if it is not a request based queue. + */ + + if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_rq_based(q)) { + err = -EOPNOTSUPP; + goto end_io; + } + part = bio->bi_bdev->bd_part; if (should_fail_request(part, bio->bi_iter.bi_size) || should_fail_request(&part_to_disk(part)->part0, @@ -2021,7 +2037,7 @@ blk_qc_t generic_make_request(struct bio *bio) do { struct request_queue *q = bdev_get_queue(bio->bi_bdev); - if (likely(blk_queue_enter(q, false) == 0)) { + if (likely(blk_queue_enter(q, bio->bi_opf & REQ_NOWAIT) == 0)) { struct bio_list lower, same; /* Create a fresh bio_list for all subordinate requests */ @@ -2046,7 +2062,11 @@ blk_qc_t generic_make_request(struct bio *bio) bio_list_merge(&bio_list_on_stack[0], &same); bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); } else { - bio_io_error(bio); + if (unlikely(!blk_queue_dying(q) && + (bio->bi_opf & REQ_NOWAIT))) + bio_wouldblock_error(bio); + else + bio_io_error(bio); } bio = bio_list_pop(&bio_list_on_stack[0]); } while (bio); diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index c974a1bbf4cb..019d881d62b7 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -119,6 +119,9 @@ struct request *blk_mq_sched_get_request(struct request_queue *q, if (likely(!data->hctx)) data->hctx = blk_mq_map_queue(q, data->ctx->cpu); + if (op & REQ_NOWAIT) + data->flags |= BLK_MQ_REQ_NOWAIT; + if (e) { data->flags |= BLK_MQ_REQ_INTERNAL; diff --git a/block/blk-mq.c b/block/blk-mq.c index c7836a1ded97..d7613ae6a269 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1538,6 +1538,8 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data); if (unlikely(!rq)) { __wbt_done(q->rq_wb, wb_acct); + if (bio->bi_opf & REQ_NOWAIT) + bio_wouldblock_error(bio); return BLK_QC_T_NONE; } @@ -1662,6 +1664,8 @@ static blk_qc_t blk_sq_make_request(struct request_queue *q, struct bio *bio) rq = blk_mq_sched_get_request(q, bio, bio->bi_opf, &data); if (unlikely(!rq)) { __wbt_done(q->rq_wb, wb_acct); + if (bio->bi_opf & REQ_NOWAIT) + bio_wouldblock_error(bio); return BLK_QC_T_NONE; } diff --git a/fs/direct-io.c b/fs/direct-io.c index a04ebea77de8..139ebd5ae1c7 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -480,8 +480,12 @@ static int dio_bio_complete(struct dio *dio, struct bio *bio) unsigned i; int err; - if (bio->bi_error) - dio->io_error = -EIO; + if (bio->bi_error) { + if (bio->bi_error == -EAGAIN && (bio->bi_opf & REQ_NOWAIT)) + dio->io_error = -EAGAIN; + else + dio->io_error = -EIO; + } if (dio->is_async && dio->op == REQ_OP_READ && dio->should_dirty) { err = bio->bi_error; @@ -1197,6 +1201,8 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, if (iov_iter_rw(iter) == WRITE) { dio->op = REQ_OP_WRITE; dio->op_flags = REQ_SYNC | REQ_IDLE; + if (iocb->ki_flags & IOCB_NOWAIT) + dio->op_flags |= REQ_NOWAIT; } else { dio->op = REQ_OP_READ; } diff --git a/include/linux/bio.h b/include/linux/bio.h index 8e521194f6fc..1a9270744b1e 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -425,6 +425,12 @@ static inline void bio_io_error(struct bio *bio) bio_endio(bio); } +static inline void bio_wouldblock_error(struct bio *bio) +{ + bio->bi_error = -EAGAIN; + bio_endio(bio); +} + struct request_queue; extern int bio_phys_segments(struct request_queue *, struct bio *); diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index d703acb55d0f..5ce4da30ba43 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -187,6 +187,7 @@ enum req_flag_bits { __REQ_PREFLUSH, /* request for cache flush */ __REQ_RAHEAD, /* read ahead, can fail anytime */ __REQ_BACKGROUND, /* background IO */ + __REQ_NOWAIT, /* Don't wait if request will block */ __REQ_NR_BITS, /* stops here */ }; @@ -203,6 +204,7 @@ enum req_flag_bits { #define REQ_PREFLUSH (1ULL << __REQ_PREFLUSH) #define REQ_RAHEAD (1ULL << __REQ_RAHEAD) #define REQ_BACKGROUND (1ULL << __REQ_BACKGROUND) +#define REQ_NOWAIT (1ULL << __REQ_NOWAIT) #define REQ_FAILFAST_MASK \ (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)