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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.h
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.h')
-rw-r--r--fs/ceph/mds_client.h7
1 files changed, 5 insertions, 2 deletions
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index a50ca0e39475..8c7c04ebb595 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -117,10 +117,13 @@ struct ceph_mds_session {
void *s_authorizer_buf, *s_authorizer_reply_buf;
size_t s_authorizer_buf_len, s_authorizer_reply_buf_len;
- /* protected by s_cap_lock */
- spinlock_t s_cap_lock;
+ /* protected by s_gen_ttl_lock */
+ spinlock_t s_gen_ttl_lock;
u32 s_cap_gen; /* inc each time we get mds stale msg */
unsigned long s_cap_ttl; /* when session caps expire */
+
+ /* protected by s_cap_lock */
+ spinlock_t s_cap_lock;
struct list_head s_caps; /* all caps issued by this session */
int s_nr_caps, s_trim_caps;
int s_num_cap_releases;