From patchwork Tue Jun 20 12:05:46 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Goldwyn Rodrigues X-Patchwork-Id: 9799337 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 21ED3601BC for ; Tue, 20 Jun 2017 12:06:12 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 12C40205A8 for ; Tue, 20 Jun 2017 12:06:12 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0772A2847B; Tue, 20 Jun 2017 12:06:12 +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 6CCB7205A8 for ; Tue, 20 Jun 2017 12:06:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751056AbdFTMGL (ORCPT ); Tue, 20 Jun 2017 08:06:11 -0400 Received: from mx2.suse.de ([195.135.220.15]:57412 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751082AbdFTMGK (ORCPT ); Tue, 20 Jun 2017 08:06:10 -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 B3354ABCA; Tue, 20 Jun 2017 12:06:08 +0000 (UTC) From: Goldwyn Rodrigues To: axboe@kernel.dk Cc: viro@ZenIV.linux.org.uk, hch@lst.de, jack@suse.cz, akpm@linux-foundation.org, linux-block@vger.kernel.org, Goldwyn Rodrigues Subject: [PATCH 07/10] block: return on congested block device Date: Tue, 20 Jun 2017 07:05:46 -0500 Message-Id: <20170620120549.23147-8-rgoldwyn@suse.de> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170620120549.23147-1-rgoldwyn@suse.de> References: <20170620120549.23147-1-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 Reviewed-by: Jens Axboe Signed-off-by: Goldwyn Rodrigues --- block/blk-core.c | 22 ++++++++++++++++++++-- block/blk-mq.c | 4 ++++ fs/direct-io.c | 10 ++++++++-- include/linux/bio.h | 6 ++++++ include/linux/blk_types.h | 4 ++++ 5 files changed, 42 insertions(+), 4 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 62cf92550512..279e3c432d7b 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -143,6 +143,7 @@ static const struct { [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" }, [BLK_STS_PROTECTION] = { -EILSEQ, "protection" }, [BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" }, + [BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" }, /* device mapper special case, should not leak out: */ [BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" }, @@ -1314,6 +1315,11 @@ 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; @@ -1961,6 +1967,14 @@ 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)) + goto not_supported; + part = bio->bi_bdev->bd_part; if (should_fail_request(part, bio->bi_iter.bi_size) || should_fail_request(&part_to_disk(part)->part0, @@ -2118,7 +2132,7 @@ 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 */ @@ -2143,7 +2157,11 @@ 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.c b/block/blk-mq.c index dd276a9e138e..ca03cd4b263f 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -293,6 +293,8 @@ static struct request *blk_mq_get_request(struct request_queue *q, data->ctx = blk_mq_get_ctx(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; @@ -1544,6 +1546,8 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) rq = blk_mq_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 e8baaabebf13..c87077d1dc33 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -479,8 +479,12 @@ static blk_status_t dio_bio_complete(struct dio *dio, struct bio *bio) unsigned i; blk_status_t err = bio->bi_status; - if (err) - dio->io_error = -EIO; + if (err) { + if (err == BLK_STS_AGAIN && (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) { bio_check_pages_dirty(bio); /* transfers ownership */ @@ -1194,6 +1198,8 @@ 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 40d054185277..36aa641cde28 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -416,6 +416,12 @@ static inline void bio_io_error(struct bio *bio) bio_endio(bio); } +static inline void bio_wouldblock_error(struct bio *bio) +{ + bio->bi_status = BLK_STS_AGAIN; + 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 dcd45b15a3a5..e210da6d14b8 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -36,6 +36,8 @@ typedef u8 __bitwise blk_status_t; /* hack for device mapper, don't use elsewhere: */ #define BLK_STS_DM_REQUEUE ((__force blk_status_t)11) +#define BLK_STS_AGAIN ((__force blk_status_t)12) + struct blk_issue_stat { u64 stat; }; @@ -224,6 +226,7 @@ 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 */ }; @@ -242,6 +245,7 @@ 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)