diff options
author | Jeff Layton <jlayton@kernel.org> | 2020-10-12 09:39:06 -0400 |
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committer | Ilya Dryomov <idryomov@gmail.com> | 2020-11-04 20:55:49 +0100 |
commit | 62575e270f661aba64778cbc5f354511cf9abb21 (patch) | |
tree | e6b08d0080e376cc6757fe1a360d45cfc987ba1d /fs/ceph/snap.c | |
parent | 3cea11cd5e3b00d91caf0b4730194039b45c5891 (diff) |
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 <pdonnell@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Diffstat (limited to 'fs/ceph/snap.c')
-rw-r--r-- | fs/ceph/snap.c | 2 |
1 files changed, 1 insertions, 1 deletions
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); |