From ea8412b284c09742d5b11721e225b4ff011aa397 Mon Sep 17 00:00:00 2001 From: Xiubo Li Date: Wed, 20 May 2020 03:51:19 -0400 Subject: [PATCH] ceph: make sure mdsc->mutex is nested in s->s_mutex to fix dead lock send_mds_reconnect takes the s_mutex while the mdsc->mutex is already held. That inverts the locking order documented in mds_client.h. Drop the mdsc->mutex, acquire the s_mutex and then reacquire the mdsc->mutex to prevent a deadlock. URL: https://tracker.ceph.com/issues/45609 Signed-off-by: Xiubo Li Reviewed-by: Jeff Layton Signed-off-by: Ilya Dryomov --- fs/ceph/mds_client.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c index 6c283c5..0e0ab01 100644 --- a/fs/ceph/mds_client.c +++ b/fs/ceph/mds_client.c @@ -3769,8 +3769,6 @@ fail: * recovering MDS might have. * * This is a relatively heavyweight operation, but it's rare. - * - * called with mdsc->mutex held. */ static void send_mds_reconnect(struct ceph_mds_client *mdsc, struct ceph_mds_session *session) @@ -4024,7 +4022,9 @@ static void check_new_map(struct ceph_mds_client *mdsc, oldstate != CEPH_MDS_STATE_STARTING) pr_info("mds%d recovery completed\n", s->s_mds); kick_requests(mdsc, i); + mutex_unlock(&mdsc->mutex); mutex_lock(&s->s_mutex); + mutex_lock(&mdsc->mutex); ceph_kick_flushing_caps(mdsc, s); mutex_unlock(&s->s_mutex); wake_up_session_caps(s, RECONNECT); -- 2.7.4