Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753062AbbKYLCU (ORCPT ); Wed, 25 Nov 2015 06:02:20 -0500 Received: from zimbra13.linbit.com ([212.69.166.240]:37018 "EHLO zimbra13.linbit.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752756AbbKYLAT (ORCPT ); Wed, 25 Nov 2015 06:00:19 -0500 From: Philipp Reisner To: Jens Axboe , linux-kernel@vger.kernel.org Cc: drbd-dev@lists.linbit.com Subject: [PATCH 20/38] drbd: fix refcount error during detach of an already failed disk Date: Wed, 25 Nov 2015 11:53:53 +0100 Message-Id: <1448448851-10343-21-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: 2185 Lines: 55 From: Lars Ellenberg A D_FAILED disk transitions as quickly as possible to D_DISKLESS. But in the "unresponsive local disk" case, there remains a time window where a administrative detach command could find the disk already failed, but some internal meta data IO against the unresponsive local disk still pending. In that case, drbd_md_get_buffer() will return NULL. Don't unconditionally call drbd_md_put_buffer(), or it will cause refcount imbalance, and prevent any further re-attach on this volume (until it is deleted and re-created). Signed-off-by: Philipp Reisner Signed-off-by: Lars Ellenberg --- drivers/block/drbd/drbd_nl.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c index 331b378..79dc3d4 100644 --- a/drivers/block/drbd/drbd_nl.c +++ b/drivers/block/drbd/drbd_nl.c @@ -1915,6 +1915,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info) static int adm_detach(struct drbd_device *device, int force) { enum drbd_state_rv retcode; + void *buffer; int ret; if (force) { @@ -1925,9 +1926,12 @@ static int adm_detach(struct drbd_device *device, int force) } drbd_suspend_io(device); /* so no-one is stuck in drbd_al_begin_io */ - drbd_md_get_buffer(device, __func__); /* make sure there is no in-flight meta-data IO */ - retcode = drbd_request_state(device, NS(disk, D_FAILED)); - drbd_md_put_buffer(device); + buffer = drbd_md_get_buffer(device, __func__); /* make sure there is no in-flight meta-data IO */ + if (buffer) { + retcode = drbd_request_state(device, NS(disk, D_FAILED)); + drbd_md_put_buffer(device); + } else /* already <= D_FAILED */ + retcode = SS_NOTHING_TO_DO; /* D_FAILED will transition to DISKLESS. */ drbd_resume_io(device); ret = wait_event_interruptible(device->misc_wait, -- 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/