There is no check in rbd_remove() to see if anybody holds open 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.
Protect the updates of the open count value with ctl_mutex to ensure
the underlying rbd device doesn't get removed while concurrently
being opened.
Signed-off-by: Alex Elder <el...@inktank.com>
---
v2: added ctl_mutex locking for rbd_open() and rbd_release()
drivers/block/rbd.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
Index: b/drivers/block/rbd.c
===================================================================
--- 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 */
@@ -356,8 +357,11 @@ static int rbd_open(struct block_device
if ((mode & FMODE_WRITE) && rbd_dev->mapping.read_only)
return -EROFS;
+ mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
rbd_get_dev(rbd_dev);
set_device_ro(bdev, rbd_dev->mapping.read_only);
+ rbd_dev->open_count++;
+ mutex_unlock(&ctl_mutex);
return 0;
}
@@ -366,7 +370,11 @@ static int rbd_release(struct gendisk *d
{
struct rbd_device *rbd_dev = disk->private_data;
+ mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+ rbd_assert(rbd_dev->open_count > 0);
+ rbd_dev->open_count--;
rbd_put_dev(rbd_dev);
+ mutex_unlock(&ctl_mutex);
return 0;
}
@@ -3764,6 +3772,11 @@ static ssize_t rbd_remove(struct bus_typ
goto done;
}
+ if (rbd_dev->open_count) {
+ ret = -EBUSY;
+ goto done;
+ }
+
rbd_remove_all_snaps(rbd_dev);
rbd_bus_del_dev(rbd_dev);
--
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