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authorJeff Layton <jlayton@kernel.org>2020-10-12 09:39:06 -0400
committerIlya Dryomov <idryomov@gmail.com>2020-11-04 20:55:49 +0100
commit62575e270f661aba64778cbc5f354511cf9abb21 (patch)
treee6b08d0080e376cc6757fe1a360d45cfc987ba1d /fs/ceph/snap.c
parent3cea11cd5e3b00d91caf0b4730194039b45c5891 (diff)
downloadlinux-62575e270f661aba64778cbc5f354511cf9abb21.tar.bz2
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.c2
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);