From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Durgin Subject: Re: [PATCH] rbd: do not allow remove of mounted-on image Date: Fri, 16 Nov 2012 14:27:03 -0800 Message-ID: <50A6BDB7.8080001@inktank.com> References: <50A65F15.6080807@inktank.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pb0-f46.google.com ([209.85.160.46]:54066 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752824Ab2KPW1h (ORCPT ); Fri, 16 Nov 2012 17:27:37 -0500 Received: by mail-pb0-f46.google.com with SMTP id wy7so2225691pbc.19 for ; Fri, 16 Nov 2012 14:27:37 -0800 (PST) In-Reply-To: <50A65F15.6080807@inktank.com> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Alex Elder Cc: ceph-devel@vger.kernel.org On 11/16/2012 07:43 AM, Alex Elder wrote: > There is no check in rbd_remove() to see if anybody holds ope the > image being removed. That's not cool. > > Add a simple open count that goes up and down with opens and closes > (releases) of the device, and don't allow an rbd image to be removed > if the count is non-zero. Both functions are protected by the > bd_mutex so there's no need for any other concurrency protection. > > Signed-off-by: Alex Elder > --- > drivers/block/rbd.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c > index fba0822..9d9a2f3 100644 > --- a/drivers/block/rbd.c > +++ b/drivers/block/rbd.c > @@ -255,6 +255,7 @@ struct rbd_device { > > /* sysfs related */ > struct device dev; > + unsigned long open_count; > }; > > static DEFINE_MUTEX(ctl_mutex); /* Serialize open/close/setup/teardown */ > @@ -358,6 +359,7 @@ static int rbd_open(struct block_device *bdev, > fmode_t mode) > > rbd_get_dev(rbd_dev); > set_device_ro(bdev, rbd_dev->mapping.read_only); > + rbd_dev->open_count++; > > return 0; > } > @@ -366,6 +368,8 @@ static int rbd_release(struct gendisk *disk, fmode_t > mode) > { > struct rbd_device *rbd_dev = disk->private_data; > > + rbd_assert(rbd_dev->open_count > 0); > + rbd_dev->open_count--; > rbd_put_dev(rbd_dev); > > return 0; > @@ -3764,6 +3768,11 @@ static ssize_t rbd_remove(struct bus_type *bus, > goto done; > } > > + if (rbd_dev->open_count) { > + ret = -EBUSY; > + goto done; > + } > + Is this protected by bd_mutex? > rbd_remove_all_snaps(rbd_dev); > rbd_bus_del_dev(rbd_dev); >