From: Goldwyn Rodrigues Subject: [PATCH 5/8] nowait aio: return on congested block device Date: Tue, 28 Feb 2017 17:36:07 -0600 Message-ID: <20170228233610.25456-6-rgoldwyn@suse.de> References: <20170228233610.25456-1-rgoldwyn@suse.de> Cc: hch@infradead.org, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, Goldwyn Rodrigues To: jack@suse.com Return-path: In-Reply-To: <20170228233610.25456-1-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 | 13 +++++++++++-- fs/direct-io.c | 11 +++++++++-- include/linux/blk_types.h | 1 + 3 files changed, 21 insertions(+), 4 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 61ba08c..e5cfc50 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1258,6 +1258,11 @@ static struct request *get_request(struct request_queue *q, unsigned int op, if (!IS_ERR(rq)) return rq; + if (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; @@ -2018,7 +2023,7 @@ 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)) { ret = q->make_request_fn(q, bio); blk_queue_exit(q); @@ -2027,7 +2032,11 @@ blk_qc_t generic_make_request(struct bio *bio) } else { struct bio *bio_next = bio_list_pop(current->bio_list); - bio_io_error(bio); + if (unlikely(bio_flagged(bio, BIO_NOWAIT))) { + bio->bi_error = -EAGAIN; + bio_endio(bio); + } else + bio_io_error(bio); bio = bio_next; } } while (bio); diff --git a/fs/direct-io.c b/fs/direct-io.c index c87bae4..2973df0 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 = bio->bi_error; + 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/blk_types.h b/include/linux/blk_types.h index 519ea2c..1d77e9b 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