ceph: fix potential race in ceph_check_caps
[ Upstream commit dc3da0461c
]
Nothing ensures that session will still be valid by the time we
dereference the pointer. Take and put a reference.
In principle, we should always be able to get a reference here, but
throw a warning if that's ever not the case.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
dac34dd4ef
commit
3e4ca8bf58
|
@ -2013,12 +2013,24 @@ ack:
|
|||
if (mutex_trylock(&session->s_mutex) == 0) {
|
||||
dout("inverting session/ino locks on %p\n",
|
||||
session);
|
||||
session = ceph_get_mds_session(session);
|
||||
spin_unlock(&ci->i_ceph_lock);
|
||||
if (took_snap_rwsem) {
|
||||
up_read(&mdsc->snap_rwsem);
|
||||
took_snap_rwsem = 0;
|
||||
}
|
||||
mutex_lock(&session->s_mutex);
|
||||
if (session) {
|
||||
mutex_lock(&session->s_mutex);
|
||||
ceph_put_mds_session(session);
|
||||
} else {
|
||||
/*
|
||||
* Because we take the reference while
|
||||
* holding the i_ceph_lock, it should
|
||||
* never be NULL. Throw a warning if it
|
||||
* ever is.
|
||||
*/
|
||||
WARN_ON_ONCE(true);
|
||||
}
|
||||
goto retry;
|
||||
}
|
||||
}
|
||||
|
|
Loading…
Reference in New Issue