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. Change all of the bare sequence counter increments to use the new helper. URL: https://tracker.ceph.com/issues/47563 Fixes: fa9967734227 ("ceph: fix potential mdsc use-after-free crash") Reported-by: Patrick Donnelly <pdonnell@xxxxxxxxxx> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> --- fs/ceph/caps.c | 2 +- fs/ceph/mds_client.c | 35 +++++++++++++++++++++++++++++------ fs/ceph/mds_client.h | 1 + fs/ceph/quota.c | 2 +- fs/ceph/snap.c | 2 +- 5 files changed, 33 insertions(+), 9 deletions(-) v2: move seq increment and check for closed session into new helper diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index c00abd7eefc1..ba0e4f44862c 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -4071,7 +4071,7 @@ void ceph_handle_caps(struct ceph_mds_session *session, vino.snap, inode); mutex_lock(&session->s_mutex); - session->s_seq++; + inc_session_sequence(session); dout(" mds%d seq %lld cap seq %u\n", session->s_mds, session->s_seq, (unsigned)seq); diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 0190555b1f9e..17b94f06826a 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -4237,7 +4237,7 @@ static void handle_lease(struct ceph_mds_client *mdsc, dname.len, dname.name); mutex_lock(&session->s_mutex); - session->s_seq++; + inc_session_sequence(session); if (!inode) { dout("handle_lease no inode %llx\n", vino.ino); @@ -4384,14 +4384,25 @@ static void maybe_recover_session(struct ceph_mds_client *mdsc) ceph_force_reconnect(fsc->sb); } +static bool check_session_closing(struct ceph_mds_session *s) +{ + int ret; + + if (s->s_state != CEPH_MDS_SESSION_CLOSING) + return true; + + dout("resending session close request for mds%d\n", s->s_mds); + ret = request_close_session(s); + if (ret < 0) + pr_err("ceph: Unable to close session to mds %d: %d\n", s->s_mds, ret); + return false; +} + bool check_session_state(struct ceph_mds_session *s) { - if (s->s_state == CEPH_MDS_SESSION_CLOSING) { - dout("resending session close request for mds%d\n", - s->s_mds); - request_close_session(s); + if (!check_session_closing(s)) return false; - } + if (s->s_ttl && time_after(jiffies, s->s_ttl)) { if (s->s_state == CEPH_MDS_SESSION_OPEN) { s->s_state = CEPH_MDS_SESSION_HUNG; @@ -4408,6 +4419,18 @@ bool check_session_state(struct ceph_mds_session *s) return true; } +/* + * If the sequence is incremented while we're waiting on a REQUEST_CLOSE reply, + * then we need to retransmit that request. + */ +void inc_session_sequence(struct ceph_mds_session *s) +{ + lockdep_assert_held(&s->s_mutex); + + s->s_seq++; + check_session_closing(s); +} + /* * delayed work -- periodically trim expired leases, renew caps with mds */ diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h index cbf8af437140..f5adbebcb38e 100644 --- a/fs/ceph/mds_client.h +++ b/fs/ceph/mds_client.h @@ -480,6 +480,7 @@ struct ceph_mds_client { extern const char *ceph_mds_op_name(int op); extern bool check_session_state(struct ceph_mds_session *s); +void inc_session_sequence(struct ceph_mds_session *s); extern struct ceph_mds_session * __ceph_lookup_mds_session(struct ceph_mds_client *, int mds); diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c index 83cb4f26b689..9b785f11e95a 100644 --- a/fs/ceph/quota.c +++ b/fs/ceph/quota.c @@ -53,7 +53,7 @@ void ceph_handle_quota(struct ceph_mds_client *mdsc, /* increment msg sequence number */ mutex_lock(&session->s_mutex); - session->s_seq++; + inc_session_sequence(session); mutex_unlock(&session->s_mutex); /* lookup inode */ 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); -- 2.26.2
