From: Goldwyn Rodrigues Subject: [PATCH 5/8] nowait aio: return on congested block device Date: Wed, 15 Mar 2017 16:51:04 -0500 Message-ID: <20170315215107.5628-6-rgoldwyn@suse.de> References: <20170315215107.5628-1-rgoldwyn@suse.de> 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, willy@infradead.org, Goldwyn Rodrigues To: linux-fsdevel@vger.kernel.org Return-path: In-Reply-To: <20170315215107.5628-1-rgoldwyn@suse.de> Sender: linux-btrfs-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org From: Goldwyn Rodrigues A new flag BIO_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. Signed-off-by: Goldwyn Rodrigues --- block/blk-core.c | 12 ++++++++++-- block/blk-mq-sched.c | 3 +++ block/blk-mq.c | 4 ++++ fs/direct-io.c | 11 +++++++++-- include/linux/bio.h | 6 ++++++ include/linux/blk_types.h | 1 + 6 files changed, 33 insertions(+), 4 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 0eeb99e..2e5cba2 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 (bio && bio_flagged(bio, BIO_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; @@ -2014,7 +2019,7 @@ 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_flagged(bio, BIO_NOWAIT)) == 0)) { struct bio_list hold; struct bio_list lower, same; @@ -2040,7 +2045,10 @@ blk_qc_t generic_make_request(struct bio *bio) bio_list_merge(&bio_list_on_stack, &same); bio_list_merge(&bio_list_on_stack, &hold); } else { - bio_io_error(bio); + if (unlikely(bio_flagged(bio, BIO_NOWAIT))) + bio_wouldblock_error(bio); + else + bio_io_error(bio); } bio = bio_list_pop(current->bio_list); } while (bio); diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index 09af8ff..40e78b5 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 (likely(bio) && bio_flagged(bio, BIO_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 159187a..942ce8c 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1518,6 +1518,8 @@ 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 && bio_flagged(bio, BIO_NOWAIT)) + bio_wouldblock_error(bio); return BLK_QC_T_NONE; } @@ -1642,6 +1644,8 @@ 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 && bio_flagged(bio, BIO_NOWAIT)) + bio_wouldblock_error(bio); return BLK_QC_T_NONE; } diff --git a/fs/direct-io.c b/fs/direct-io.c index a04ebea..f6835d3 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -386,6 +386,9 @@ dio_bio_alloc(struct dio *dio, struct dio_submit *sdio, else bio->bi_end_io = dio_bio_end_io; + if (dio->iocb->ki_flags & IOCB_NOWAIT) + bio_set_flag(bio, BIO_NOWAIT); + sdio->bio = bio; sdio->logical_offset_in_bio = sdio->cur_page_fs_offset; } @@ -480,8 +483,12 @@ 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_flagged(bio, BIO_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; diff --git a/include/linux/bio.h b/include/linux/bio.h index 8e52119..1a92707 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 d703acb..514c08e 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -102,6 +102,7 @@ struct bio { #define BIO_REFFED 8 /* bio has elevated ->bi_cnt */ #define BIO_THROTTLED 9 /* This bio has already been subjected to * throttling rules. Don't do it again. */ +#define BIO_NOWAIT 10 /* don't block over blk device congestion */ /* * Flags starting here get preserved by bio_reset() - this includes -- 2.10.2