rbd: prevent busy loop when requesting exclusive lock

rbd: prevent busy loop when requesting exclusive lock

commit 9d01e07fd1bfb4daae156ab528aa196f5ac2b2bc upstream.

Due to rbd_try_acquire_lock() effectively swallowing all but
EBLOCKLISTED error from rbd_try_lock() ("request lock anyway") and
rbd_request_lock() returning ETIMEDOUT error not only for an actual
notify timeout but also when the lock owner doesn't respond, a busy
loop inside of rbd_acquire_lock() between rbd_try_acquire_lock() and
rbd_request_lock() is possible.

Requesting the lock on EBUSY error (returned by get_lock_owner_info()
if an incompatible lock or invalid lock owner is detected) makes very
little sense.  The same goes for ETIMEDOUT error (might pop up pretty
much anywhere if osd_request_timeout option is set) and many others.

Just fail I/O requests on rbd_dev->acquiring_list immediately on any
error from rbd_try_lock().

Cc: stable@vger.kernel.org # 588159009d5b: rbd: retrieve and check lock owner twice before blocklisting
Cc: stable@vger.kernel.org
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>