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authorAlex Elder <elder@dreamhost.com>2012-01-12 17:48:10 -0800
committerSage Weil <sage@newdream.net>2012-02-02 12:49:19 -0800
commitd8fb02abdc39f92a1066313e2b17047876afa8f9 (patch)
tree32f8126683dd185411b701b79d23900cf6c02035 /fs/ceph/mds_client.c
parent32852a81bccd9e3d1953b894966393d1b546576d (diff)
ceph: create a new session lock to avoid lock inversion
Lockdep was reporting a possible circular lock dependency in dentry_lease_is_valid(). That function needs to sample the session's s_cap_gen and and s_cap_ttl fields coherently, but needs to do so while holding a dentry lock. The s_cap_lock field was being used to protect the two fields, but that can't be taken while holding a lock on a dentry within the session. In most cases, the s_cap_gen and s_cap_ttl fields only get operated on separately. But in three cases they need to be updated together. Implement a new lock to protect the spots updating both fields atomically is required. Signed-off-by: Alex Elder <elder@dreamhost.com> Reviewed-by: Sage Weil <sage@newdream.net>
Diffstat (limited to 'fs/ceph/mds_client.c')
-rw-r--r--fs/ceph/mds_client.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index be1415fcaac8..a4fdf9397a90 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -400,9 +400,11 @@ static struct ceph_mds_session *register_session(struct ceph_mds_client *mdsc,
s->s_con.peer_name.type = CEPH_ENTITY_TYPE_MDS;
s->s_con.peer_name.num = cpu_to_le64(mds);
- spin_lock_init(&s->s_cap_lock);
+ spin_lock_init(&s->s_gen_ttl_lock);
s->s_cap_gen = 0;
s->s_cap_ttl = 0;
+
+ spin_lock_init(&s->s_cap_lock);
s->s_renew_requested = 0;
s->s_renew_seq = 0;
INIT_LIST_HEAD(&s->s_caps);
@@ -2328,10 +2330,10 @@ static void handle_session(struct ceph_mds_session *session,
case CEPH_SESSION_STALE:
pr_info("mds%d caps went stale, renewing\n",
session->s_mds);
- spin_lock(&session->s_cap_lock);
+ spin_lock(&session->s_gen_ttl_lock);
session->s_cap_gen++;
session->s_cap_ttl = 0;
- spin_unlock(&session->s_cap_lock);
+ spin_unlock(&session->s_gen_ttl_lock);
send_renew_caps(mdsc, session);
break;