From 62575e270f661aba64778cbc5f354511cf9abb21 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Mon, 12 Oct 2020 09:39:06 -0400 Subject: ceph: check session state after bumping session->s_seq Some messages sent by the MDS entail a session sequence number increment, and the MDS will drop certain types of requests on the floor when the sequence numbers don't match. In particular, a REQUEST_CLOSE message can cross with one of the sequence morphing messages from the MDS which can cause the client to stall, waiting for a response that will never come. Originally, this meant an up to 5s delay before the recurring workqueue job kicked in and resent the request, but a recent change made it so that the client would never resend, causing a 60s stall unmounting and sometimes a blockisting event. Add a new helper for incrementing the session sequence and then testing to see whether a REQUEST_CLOSE needs to be resent, and move the handling of CEPH_MDS_SESSION_CLOSING into that function. Change all of the bare sequence counter increments to use the new helper. Reorganize check_session_state with a switch statement. It should no longer be called when the session is CLOSING, so throw a warning if it ever is (but still handle that case sanely). [ idryomov: whitespace, pr_err() call fixup ] URL: https://tracker.ceph.com/issues/47563 Fixes: fa9967734227 ("ceph: fix potential mdsc use-after-free crash") Reported-by: Patrick Donnelly Signed-off-by: Jeff Layton Reviewed-by: Ilya Dryomov Reviewed-by: Xiubo Li Signed-off-by: Ilya Dryomov --- fs/ceph/snap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/ceph/snap.c') diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index 0da39c16dab4..b611f829cb61 100644 --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -873,7 +873,7 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc, ceph_snap_op_name(op), split, trace_len); mutex_lock(&session->s_mutex); - session->s_seq++; + inc_session_sequence(session); mutex_unlock(&session->s_mutex); down_write(&mdsc->snap_rwsem); -- cgit v1.2.3-70-g09d2