Syncing OSD requests doesn't really work. A single image request may
be comprised of multiple object requests, each of which can go through
a series of OSD requests (original, copyups, etc). On top of that, the
OSD cliest may be shared with other rbd devices.
What we want is to ensure that all in-flight image requests complete.
Introduce rbd_dev->running_list and block in RBD_LOCK_STATE_RELEASING
until that happens. New OSD requests may be started during this time.
Note that __rbd_img_handle_request() acquires rbd_dev->lock_rwsem only
if need_exclusive_lock() returns true. This avoids a deadlock similar
to the one outlined in the previous commit between unlock and I/O that
doesn't require lock, such as a read with object-map feature disabled.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
e1fddc8fdd