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author | Alex Elder <elder@dreamhost.com> | 2012-01-12 17:48:10 -0800 |
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committer | Sage Weil <sage@newdream.net> | 2012-02-02 12:49:19 -0800 |
commit | d8fb02abdc39f92a1066313e2b17047876afa8f9 (patch) | |
tree | 32f8126683dd185411b701b79d23900cf6c02035 /fs/ceph/mds_client.c | |
parent | 32852a81bccd9e3d1953b894966393d1b546576d (diff) | |
download | linux-stable-d8fb02abdc39f92a1066313e2b17047876afa8f9.tar.gz linux-stable-d8fb02abdc39f92a1066313e2b17047876afa8f9.tar.bz2 linux-stable-d8fb02abdc39f92a1066313e2b17047876afa8f9.zip |
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.c | 8 |
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; |