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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.h | |
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.h')
-rw-r--r-- | fs/ceph/mds_client.h | 7 |
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; |