From patchwork Wed Jul 26 23:58:00 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Goldwyn Rodrigues X-Patchwork-Id: 9866045 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 D32B860225 for ; Wed, 26 Jul 2017 23:59:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C46E3287C9 for ; Wed, 26 Jul 2017 23:59:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B94A7287D8; Wed, 26 Jul 2017 23:59:20 +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 1B7E5287C9 for ; Wed, 26 Jul 2017 23:59:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751465AbdGZX6d (ORCPT ); Wed, 26 Jul 2017 19:58:33 -0400 Received: from mx2.suse.de ([195.135.220.15]:46025 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751078AbdGZX6d (ORCPT ); Wed, 26 Jul 2017 19:58:33 -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 8BADEAE65; Wed, 26 Jul 2017 23:58:31 +0000 (UTC) From: Goldwyn Rodrigues To: linux-block@vger.kernel.org Cc: hch@infradead.org, jack@suse.cz, linux-raid@vger.kernel.org, dm-devel@redhat.com, Goldwyn Rodrigues Subject: [PATCH 3/9] md: raid1 nowait support Date: Wed, 26 Jul 2017 18:58:00 -0500 Message-Id: <20170726235806.12148-4-rgoldwyn@suse.de> X-Mailer: git-send-email 2.12.3 In-Reply-To: <20170726235806.12148-1-rgoldwyn@suse.de> References: <20170726235806.12148-1-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 The RAID1 driver would bail with EAGAIN in case of: + I/O has to wait for a barrier + array is frozen + Area is suspended + There are too many pending I/O that it will be queued. To facilitate error for wait barriers, wait_barrier() is returning bool. True in case if there was a wait (or is not required). False in case a wait was required, but was not performed. Signed-off-by: Goldwyn Rodrigues --- drivers/md/raid1.c | 74 +++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 57 insertions(+), 17 deletions(-) diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 3febfc8391fb..66ca4288e3e8 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -903,8 +903,9 @@ static void lower_barrier(struct r1conf *conf, sector_t sector_nr) wake_up(&conf->wait_barrier); } -static void _wait_barrier(struct r1conf *conf, int idx) +static bool _wait_barrier(struct r1conf *conf, int idx, bool nowait) { + bool ret = true; /* * We need to increase conf->nr_pending[idx] very early here, * then raise_barrier() can be blocked when it waits for @@ -935,7 +936,7 @@ static void _wait_barrier(struct r1conf *conf, int idx) */ if (!READ_ONCE(conf->array_frozen) && !atomic_read(&conf->barrier[idx])) - return; + return ret; /* * After holding conf->resync_lock, conf->nr_pending[idx] @@ -953,18 +954,26 @@ static void _wait_barrier(struct r1conf *conf, int idx) */ wake_up(&conf->wait_barrier); /* Wait for the barrier in same barrier unit bucket to drop. */ - wait_event_lock_irq(conf->wait_barrier, - !conf->array_frozen && - !atomic_read(&conf->barrier[idx]), - conf->resync_lock); + if (conf->array_frozen || atomic_read(&conf->barrier[idx])) { + if (nowait) + ret = false; + else + wait_event_lock_irq(conf->wait_barrier, + !conf->array_frozen && + !atomic_read(&conf->barrier[idx]), + conf->resync_lock); + } atomic_inc(&conf->nr_pending[idx]); atomic_dec(&conf->nr_waiting[idx]); spin_unlock_irq(&conf->resync_lock); + return ret; } -static void wait_read_barrier(struct r1conf *conf, sector_t sector_nr) +static bool wait_read_barrier(struct r1conf *conf, sector_t sector_nr, + bool nowait) { int idx = sector_to_idx(sector_nr); + bool ret = true; /* * Very similar to _wait_barrier(). The difference is, for read @@ -976,7 +985,7 @@ static void wait_read_barrier(struct r1conf *conf, sector_t sector_nr) atomic_inc(&conf->nr_pending[idx]); if (!READ_ONCE(conf->array_frozen)) - return; + return ret; spin_lock_irq(&conf->resync_lock); atomic_inc(&conf->nr_waiting[idx]); @@ -987,19 +996,28 @@ static void wait_read_barrier(struct r1conf *conf, sector_t sector_nr) */ wake_up(&conf->wait_barrier); /* Wait for array to be unfrozen */ - wait_event_lock_irq(conf->wait_barrier, - !conf->array_frozen, - conf->resync_lock); + if (conf->array_frozen) { + /* If nowait flag is set, return false to + * show we did not wait + */ + if (nowait) + ret = false; + else + wait_event_lock_irq(conf->wait_barrier, + !conf->array_frozen, + conf->resync_lock); + } atomic_inc(&conf->nr_pending[idx]); atomic_dec(&conf->nr_waiting[idx]); spin_unlock_irq(&conf->resync_lock); + return ret; } -static void wait_barrier(struct r1conf *conf, sector_t sector_nr) +static bool wait_barrier(struct r1conf *conf, sector_t sector_nr, bool nowait) { int idx = sector_to_idx(sector_nr); - _wait_barrier(conf, idx); + return _wait_barrier(conf, idx, nowait); } static void wait_all_barriers(struct r1conf *conf) @@ -1007,7 +1025,7 @@ static void wait_all_barriers(struct r1conf *conf) int idx; for (idx = 0; idx < BARRIER_BUCKETS_NR; idx++) - _wait_barrier(conf, idx); + _wait_barrier(conf, idx, false); } static void _allow_barrier(struct r1conf *conf, int idx) @@ -1223,7 +1241,11 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio, * Still need barrier for READ in case that whole * array is frozen. */ - wait_read_barrier(conf, bio->bi_iter.bi_sector); + if (!wait_read_barrier(conf, bio->bi_iter.bi_sector, + bio->bi_opf & REQ_NOWAIT)) { + bio_wouldblock_error(bio); + return; + } if (!r1_bio) r1_bio = alloc_r1bio(mddev, bio); @@ -1333,6 +1355,11 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, * an interruptible wait. */ DEFINE_WAIT(w); + if (bio->bi_opf & REQ_NOWAIT) { + bio_wouldblock_error(bio); + return; + } + for (;;) { sigset_t full, old; prepare_to_wait(&conf->wait_barrier, @@ -1351,7 +1378,11 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, } finish_wait(&conf->wait_barrier, &w); } - wait_barrier(conf, bio->bi_iter.bi_sector); + if (!wait_barrier(conf, bio->bi_iter.bi_sector, + bio->bi_opf & REQ_NOWAIT)) { + bio_wouldblock_error(bio); + return; + } r1_bio = alloc_r1bio(mddev, bio); r1_bio->sectors = max_write_sectors; @@ -1359,6 +1390,10 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, if (conf->pending_count >= max_queued_requests) { md_wakeup_thread(mddev->thread); raid1_log(mddev, "wait queued"); + if (bio->bi_opf & REQ_NOWAIT) { + bio_wouldblock_error(bio); + return; + } wait_event(conf->wait_barrier, conf->pending_count < max_queued_requests); } @@ -1442,6 +1477,11 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, /* Wait for this device to become unblocked */ int j; + if (bio->bi_opf & REQ_NOWAIT) { + bio_wouldblock_error(bio); + return; + } + for (j = 0; j < i; j++) if (r1_bio->bios[j]) rdev_dec_pending(conf->mirrors[j].rdev, mddev); @@ -1449,7 +1489,7 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio, allow_barrier(conf, bio->bi_iter.bi_sector); raid1_log(mddev, "wait rdev %d blocked", blocked_rdev->raid_disk); md_wait_for_blocked_rdev(blocked_rdev, mddev); - wait_barrier(conf, bio->bi_iter.bi_sector); + wait_barrier(conf, bio->bi_iter.bi_sector, false); goto retry_write; }