Every time a watch is reestablished after getting lost, we need to
update the cookie which involves quiescing exclusive lock. For this,
we transition from RBD_LOCK_STATE_LOCKED to RBD_LOCK_STATE_QUIESCING
roughly for the duration of rbd_reacquire_lock() call. If the mapping
is exclusive and I/O happens to arrive in this time window, it's failed
with EROFS (later translated to EIO) based on the wrong assumption in
rbd_img_exclusive_lock() -- "lock got released?" check there stopped
making sense with commit a2b1da09793d ("rbd: lock should be quiesced on
reacquire").
To make it worse, any such I/O is added to the acquiring list before
EROFS is returned and this sets up for violating rbd_lock_del_request()
precondition that the request is either on the running list or not on
any list at all -- see commit ded080c86b3f ("rbd: don't move requests
to the running list on errors"). rbd_lock_del_request() ends up
processing these requests as if they were on the running list which
screws up quiescing_wait completion counter and ultimately leads to
rbd_assert(!completion_done(&rbd_dev->quiescing_wait));
being triggered on the next watch error.
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
---
drivers/block/rbd.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 77a9f19a0035..dc4ddae4f7eb 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -3457,6 +3457,7 @@ static void rbd_lock_del_request(struct rbd_img_request *img_req)
lockdep_assert_held(&rbd_dev->lock_rwsem);
spin_lock(&rbd_dev->lock_lists_lock);
if (!list_empty(&img_req->lock_item)) {
+ rbd_assert(!list_empty(&rbd_dev->running_list));
list_del_init(&img_req->lock_item);
need_wakeup = (rbd_dev->lock_state == RBD_LOCK_STATE_QUIESCING &&
list_empty(&rbd_dev->running_list));
@@ -3476,11 +3477,6 @@ static int rbd_img_exclusive_lock(struct rbd_img_request *img_req)
if (rbd_lock_add_request(img_req))
return 1;
- if (rbd_dev->opts->exclusive) {
- WARN_ON(1); /* lock got released? */
- return -EROFS;
- }
-
/*
* Note the use of mod_delayed_work() in rbd_acquire_lock()
* and cancel_delayed_work() in wake_lock_waiters().
@@ -4601,6 +4597,10 @@ static void rbd_reacquire_lock(struct rbd_device *rbd_dev)
rbd_warn(rbd_dev, "failed to update lock cookie: %d",
ret);
+ if (rbd_dev->opts->exclusive)
+ rbd_warn(rbd_dev,
+ "temporarily releasing lock on exclusive mapping");
+
/*
* Lock cookie cannot be updated on older OSDs, so do
* a manual release and queue an acquire.
--
2.45.1
