On 11/16/2012 04:27 PM, Josh Durgin wrote:
> 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 <[email protected]>
>> ---
>> 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?
No it's not, and that's a very good point.
I'll have to look at that over the weekend.
Thanks.
-Alex
>> rbd_remove_all_snaps(rbd_dev);
>> rbd_bus_del_dev(rbd_dev);
>>
>
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