From patchwork Thu Jun 15 15:59:59 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Goldwyn Rodrigues X-Patchwork-Id: 9789049 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 026B260384 for ; Thu, 15 Jun 2017 16:00:27 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E83562654B for ; Thu, 15 Jun 2017 16:00:26 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DD17727FA6; Thu, 15 Jun 2017 16:00:26 +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=ham 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 634DC2654B for ; Thu, 15 Jun 2017 16:00:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751959AbdFOQAZ (ORCPT ); Thu, 15 Jun 2017 12:00:25 -0400 Received: from mx2.suse.de ([195.135.220.15]:53292 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750803AbdFOQAY (ORCPT ); Thu, 15 Jun 2017 12:00:24 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 1C309AD06; Thu, 15 Jun 2017 16:00:22 +0000 (UTC) From: Goldwyn Rodrigues To: linux-fsdevel@vger.kernel.org Cc: jack@suse.com, hch@infradead.org, linux-block@vger.kernel.org, axboe@kernel.dk, linux-api@vger.kernel.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, Goldwyn Rodrigues Subject: [PATCH 07/10] block: return on congested block device Date: Thu, 15 Jun 2017 10:59:59 -0500 Message-Id: <20170615160002.17233-8-rgoldwyn@suse.de> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170615160002.17233-1-rgoldwyn@suse.de> References: <20170615160002.17233-1-rgoldwyn@suse.de> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@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. Reviewed-by: Christoph Hellwig Signed-off-by: Goldwyn Rodrigues Reviewed-by: Jens Axboe --- block/blk-core.c | 23 +++++++++++++++++++++-- block/blk-mq-sched.c | 3 +++ block/blk-mq.c | 2 ++ fs/direct-io.c | 10 ++++++++-- include/linux/bio.h | 6 ++++++ include/linux/blk_types.h | 2 ++ 6 files changed, 42 insertions(+), 4 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index a7421b772d0e..972d6fdb1432 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1256,6 +1256,11 @@ 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; @@ -1900,6 +1905,16 @@ generic_make_request_checks(struct bio *bio) goto end_io; } + /* + * For a REQ_NOWAIT based request, return -EOPNOTSUPP + * if queue 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, @@ -2057,7 +2072,7 @@ 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 */ @@ -2082,7 +2097,11 @@ 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 1f5b692526ae..9a1dea8b964e 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -83,6 +83,9 @@ 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 bb66c96850b1..86d86626ef00 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1562,6 +1562,8 @@ 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; } 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 d1b04b0e99cf..cc0aa4315383 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -418,6 +418,12 @@ 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 61339bc44400..c87990aec66e 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -205,6 +205,7 @@ enum req_flag_bits { /* command specific flags for REQ_OP_WRITE_ZEROES: */ __REQ_NOUNMAP, /* do not free blocks when zeroing */ + __REQ_NOWAIT, /* Don't wait if request will block */ __REQ_NR_BITS, /* stops here */ }; @@ -223,6 +224,7 @@ enum req_flag_bits { #define REQ_BACKGROUND (1ULL << __REQ_BACKGROUND) #define REQ_NOUNMAP (1ULL << __REQ_NOUNMAP) +#define REQ_NOWAIT (1ULL << __REQ_NOWAIT) #define REQ_FAILFAST_MASK \ (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)