ceph: revoke osd request message on request completion

If an osd has failed or returned and a request has been sent twice, it's
possible to get a reply and unregister the request while the request
message is queued for delivery.  Since the message references the caller's
page vector, we need to revoke it before completing.

Signed-off-by: Sage Weil <sage@newdream.net>

diff --cc fs/ceph/osd_client.c
Simple merge