rbd: set removing flag while holding list lock
When unmapping a device, its id is supplied, and that is used to
look up which rbd device should be unmapped. Looking up the
device involves searching the rbd device list while holding
a spinlock that protects access to that list.
Currently all of this is done under protection of the control lock,
but that protection is going away soon. To ensure the rbd_dev is
still valid (still on the list) while setting its REMOVING flag, do
so while still holding the list lock. To do so, get rid of
__rbd_get_dev(), and open code what it did in the one place it
was used.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index fd2795d..9eead487 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -5090,23 +5090,6 @@
return (ssize_t)rc;
}
-static struct rbd_device *__rbd_get_dev(unsigned long dev_id)
-{
- struct list_head *tmp;
- struct rbd_device *rbd_dev;
-
- spin_lock(&rbd_dev_list_lock);
- list_for_each(tmp, &rbd_dev_list) {
- rbd_dev = list_entry(tmp, struct rbd_device, node);
- if (rbd_dev->dev_id == dev_id) {
- spin_unlock(&rbd_dev_list_lock);
- return rbd_dev;
- }
- }
- spin_unlock(&rbd_dev_list_lock);
- return NULL;
-}
-
static void rbd_dev_device_release(struct device *dev)
{
struct rbd_device *rbd_dev = dev_to_rbd_dev(dev);
@@ -5151,7 +5134,8 @@
size_t count)
{
struct rbd_device *rbd_dev = NULL;
- int target_id;
+ struct list_head *tmp;
+ int dev_id;
unsigned long ul;
int ret;
@@ -5160,26 +5144,33 @@
return ret;
/* convert to int; abort if we lost anything in the conversion */
- target_id = (int) ul;
- if (target_id != ul)
+ dev_id = (int)ul;
+ if (dev_id != ul)
return -EINVAL;
mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
- rbd_dev = __rbd_get_dev(target_id);
- if (!rbd_dev) {
- ret = -ENOENT;
- goto done;
+ ret = -ENOENT;
+ spin_lock(&rbd_dev_list_lock);
+ list_for_each(tmp, &rbd_dev_list) {
+ rbd_dev = list_entry(tmp, struct rbd_device, node);
+ if (rbd_dev->dev_id == dev_id) {
+ ret = 0;
+ break;
+ }
}
-
- spin_lock_irq(&rbd_dev->lock);
- if (rbd_dev->open_count)
- ret = -EBUSY;
- else
- set_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags);
- spin_unlock_irq(&rbd_dev->lock);
+ if (!ret) {
+ spin_lock_irq(&rbd_dev->lock);
+ if (rbd_dev->open_count)
+ ret = -EBUSY;
+ else
+ set_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags);
+ spin_unlock_irq(&rbd_dev->lock);
+ }
+ spin_unlock(&rbd_dev_list_lock);
if (ret < 0)
goto done;
+
rbd_bus_del_dev(rbd_dev);
ret = rbd_dev_header_watch_sync(rbd_dev, false);
if (ret)