From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alex Elder , Josh Durgin Subject: [PATCH 3.10 096/129] rbd: protect against concurrent unmaps Date: Mon, 6 Jan 2014 14:38:45 -0800 Message-Id: <20140106223902.349996992@linuxfoundation.org> In-Reply-To: <20140106223859.589799655@linuxfoundation.org> References: <20140106223859.589799655@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alex Elder commit 82a442d239695a242c4d584464c9606322cd02aa upstream. Make sure two concurrent unmap operations on the same rbd device won't collide, by only proceeding with the removal and cleanup of a device if is not already underway. Signed-off-by: Alex Elder Reviewed-by: Josh Durgin Signed-off-by: Greg Kroah-Hartman --- drivers/block/rbd.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -5108,6 +5108,7 @@ static ssize_t rbd_remove(struct bus_typ struct list_head *tmp; int dev_id; unsigned long ul; + bool already = false; int ret; ret = strict_strtoul(buf, 10, &ul); @@ -5135,11 +5136,12 @@ static ssize_t rbd_remove(struct bus_typ if (rbd_dev->open_count) ret = -EBUSY; else - set_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags); + already = test_and_set_bit(RBD_DEV_FLAG_REMOVING, + &rbd_dev->flags); spin_unlock_irq(&rbd_dev->lock); } spin_unlock(&rbd_dev_list_lock); - if (ret < 0) + if (ret < 0 || already) goto done; rbd_bus_del_dev(rbd_dev);