Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753162AbbKYLC2 (ORCPT ); Wed, 25 Nov 2015 06:02:28 -0500 Received: from zimbra13.linbit.com ([212.69.166.240]:37028 "EHLO zimbra13.linbit.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752748AbbKYLAR (ORCPT ); Wed, 25 Nov 2015 06:00:17 -0500 From: Philipp Reisner To: Jens Axboe , linux-kernel@vger.kernel.org Cc: drbd-dev@lists.linbit.com Subject: [PATCH 35/38] drbd: make suspend_io() / resume_io() must be thread and recursion safe Date: Wed, 25 Nov 2015 11:54:08 +0100 Message-Id: <1448448851-10343-36-git-send-email-philipp.reisner@linbit.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1448448851-10343-1-git-send-email-philipp.reisner@linbit.com> References: <1448448851-10343-1-git-send-email-philipp.reisner@linbit.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3294 Lines: 89 Avoid to prematurely resume application IO: don't set/clear a single bit, but inc/dec an atomic counter. Signed-off-by: Philipp Reisner Signed-off-by: Lars Ellenberg --- drivers/block/drbd/drbd_int.h | 4 ++-- drivers/block/drbd/drbd_nl.c | 8 +++++--- drivers/block/drbd/drbd_state.c | 2 +- 3 files changed, 8 insertions(+), 6 deletions(-) diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h index a262653..df3d89d 100644 --- a/drivers/block/drbd/drbd_int.h +++ b/drivers/block/drbd/drbd_int.h @@ -500,7 +500,6 @@ enum { MD_NO_FUA, /* Users wants us to not use FUA/FLUSH on meta data dev */ - SUSPEND_IO, /* suspend application io */ BITMAP_IO, /* suspend application io; once no more io in flight, start bitmap io */ BITMAP_IO_QUEUED, /* Started bitmap IO */ @@ -880,6 +879,7 @@ struct drbd_device { atomic_t rs_pending_cnt; /* RS request/data packets on the wire */ atomic_t unacked_cnt; /* Need to send replies for */ atomic_t local_cnt; /* Waiting for local completion */ + atomic_t suspend_cnt; /* Interval tree of pending local requests */ struct rb_root read_requests; @@ -2263,7 +2263,7 @@ static inline bool may_inc_ap_bio(struct drbd_device *device) if (drbd_suspended(device)) return false; - if (test_bit(SUSPEND_IO, &device->flags)) + if (atomic_read(&device->suspend_cnt)) return false; /* to avoid potential deadlock or bitmap corruption, diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c index 6137789..c7cd3df 100644 --- a/drivers/block/drbd/drbd_nl.c +++ b/drivers/block/drbd/drbd_nl.c @@ -865,9 +865,11 @@ char *ppsize(char *buf, unsigned long long size) * and can be long lived. * This changes an device->flag, is triggered by drbd internals, * and should be short-lived. */ +/* It needs to be a counter, since multiple threads might + independently suspend and resume IO. */ void drbd_suspend_io(struct drbd_device *device) { - set_bit(SUSPEND_IO, &device->flags); + atomic_inc(&device->suspend_cnt); if (drbd_suspended(device)) return; wait_event(device->misc_wait, !atomic_read(&device->ap_bio_cnt)); @@ -875,8 +877,8 @@ void drbd_suspend_io(struct drbd_device *device) void drbd_resume_io(struct drbd_device *device) { - clear_bit(SUSPEND_IO, &device->flags); - wake_up(&device->misc_wait); + if (atomic_dec_and_test(&device->suspend_cnt)) + wake_up(&device->misc_wait); } /** diff --git a/drivers/block/drbd/drbd_state.c b/drivers/block/drbd/drbd_state.c index f022e99..5a7ef78 100644 --- a/drivers/block/drbd/drbd_state.c +++ b/drivers/block/drbd/drbd_state.c @@ -1484,7 +1484,7 @@ int drbd_bitmap_io_from_worker(struct drbd_device *device, D_ASSERT(device, current == first_peer_device(device)->connection->worker.task); /* open coded non-blocking drbd_suspend_io(device); */ - set_bit(SUSPEND_IO, &device->flags); + atomic_inc(&device->suspend_cnt); drbd_bm_lock(device, why, flags); rv = io_fn(device); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/