rbd: do a safe list traversal in rbd_img_request_submit()

It's possible that the reference to the object request dropped
inside the loop in rbd_img_request_submit() will be the last
one, in which case the content of the object pointer can't be

Use a safe form of the object request list traversal to avoid

This resolves:

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
1 file changed