Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[sfrench/cifs-2.6.git] / fs / ceph / caps.c

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index aa2239fa9a3b7852feaba95830b0d78f6ec32701..d9400534b2790158e072a547d652876f35079f9c 100644 (file)
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -858,6 +858,8 @@ static int __ceph_is_any_caps(struct ceph_inode_info *ci)
 }
 
 /*
+ * Remove a cap.  Take steps to deal with a racing iterate_session_caps.
+ *
  * caller should hold i_lock.
  * caller will not hold session s_mutex if called from destroy_inode.
  */
@@ -866,15 +868,10 @@ void __ceph_remove_cap(struct ceph_cap *cap)
        struct ceph_mds_session *session = cap->session;
        struct ceph_inode_info *ci = cap->ci;
        struct ceph_mds_client *mdsc = &ceph_client(ci->vfs_inode.i_sb)->mdsc;
+       int removed = 0;
 
        dout("__ceph_remove_cap %p from %p\n", cap, &ci->vfs_inode);
 
-       /* remove from inode list */
-       rb_erase(&cap->ci_node, &ci->i_caps);
-       cap->ci = NULL;
-       if (ci->i_auth_cap == cap)
-               ci->i_auth_cap = NULL;
-
        /* remove from session list */
        spin_lock(&session->s_cap_lock);
        if (session->s_cap_iterator == cap) {
@@ -885,10 +882,18 @@ void __ceph_remove_cap(struct ceph_cap *cap)
                list_del_init(&cap->session_caps);
                session->s_nr_caps--;
                cap->session = NULL;
+               removed = 1;
        }
+       /* protect backpointer with s_cap_lock: see iterate_session_caps */
+       cap->ci = NULL;
        spin_unlock(&session->s_cap_lock);
 
-       if (cap->session == NULL)
+       /* remove from inode list */
+       rb_erase(&cap->ci_node, &ci->i_caps);
+       if (ci->i_auth_cap == cap)
+               ci->i_auth_cap = NULL;
+
+       if (removed)
                ceph_put_cap(cap);
 
        if (!__ceph_is_any_caps(ci) && ci->i_snap_realm) {
@@ -1861,8 +1866,8 @@ static void kick_flushing_capsnaps(struct ceph_mds_client *mdsc,
                } else {
                        pr_err("%p auth cap %p not mds%d ???\n", inode,
                               cap, session->s_mds);
-                       spin_unlock(&inode->i_lock);
                }
+               spin_unlock(&inode->i_lock);
        }
 }