5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ilya Dryomov <idryomov@xxxxxxxxx>
commit ded080c86b3f99683774af0441a58fc2e3d60cae upstream.
The running list is supposed to contain requests that are pinning the
exclusive lock, i.e. those that must be flushed before exclusive lock
is released. When wake_lock_waiters() is called to handle an error,
requests on the acquiring list are failed with that error and no
flushing takes place. Briefly moving them to the running list is not
only pointless but also harmful: if exclusive lock gets acquired
before all of their state machines are scheduled and go through
rbd_lock_del_request(), we trigger
rbd_assert(list_empty(&rbd_dev->running_list));
in rbd_try_acquire_lock().
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 637cd060537d ("rbd: new exclusive lock wait/wake code")
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Reviewed-by: Dongsheng Yang <dongsheng.yang@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/block/rbd.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -3603,14 +3603,15 @@ static bool rbd_lock_add_request(struct
static void rbd_lock_del_request(struct rbd_img_request *img_req)
{
struct rbd_device *rbd_dev = img_req->rbd_dev;
- bool need_wakeup;
+ bool need_wakeup = false;
lockdep_assert_held(&rbd_dev->lock_rwsem);
spin_lock(&rbd_dev->lock_lists_lock);
- rbd_assert(!list_empty(&img_req->lock_item));
- list_del_init(&img_req->lock_item);
- need_wakeup = (rbd_dev->lock_state == RBD_LOCK_STATE_RELEASING &&
- list_empty(&rbd_dev->running_list));
+ if (!list_empty(&img_req->lock_item)) {
+ list_del_init(&img_req->lock_item);
+ need_wakeup = (rbd_dev->lock_state == RBD_LOCK_STATE_RELEASING &&
+ list_empty(&rbd_dev->running_list));
+ }
spin_unlock(&rbd_dev->lock_lists_lock);
if (need_wakeup)
complete(&rbd_dev->releasing_wait);
@@ -3997,14 +3998,19 @@ static void wake_lock_waiters(struct rbd
return;
}
- list_for_each_entry(img_req, &rbd_dev->acquiring_list, lock_item) {
+ while (!list_empty(&rbd_dev->acquiring_list)) {
+ img_req = list_first_entry(&rbd_dev->acquiring_list,
+ struct rbd_img_request, lock_item);
mutex_lock(&img_req->state_mutex);
rbd_assert(img_req->state == RBD_IMG_EXCLUSIVE_LOCK);
+ if (!result)
+ list_move_tail(&img_req->lock_item,
+ &rbd_dev->running_list);
+ else
+ list_del_init(&img_req->lock_item);
rbd_img_schedule(img_req, result);
mutex_unlock(&img_req->state_mutex);
}
-
- list_splice_tail_init(&rbd_dev->acquiring_list, &rbd_dev->running_list);
}
static int get_lock_owner_info(struct rbd_device *rbd_dev,
