ceph: hold i_ceph_lock when removing caps for freeing inode

commit d6e47819721ae2d9d090058ad5570a66f3c42e39 upstream.

ceph_d_revalidate(, LOOKUP_RCU) may call __ceph_caps_issued_mask()
on a freeing inode.

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index f916cd7..82df349 100644 (file)
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -1081,20 +1081,23 @@ static int send_cap_msg(struct ceph_mds_session *session,
 }
 
 /*
- * Queue cap releases when an inode is dropped from our cache.  Since
- * inode is about to be destroyed, there is no need for i_ceph_lock.
+ * Queue cap releases when an inode is dropped from our cache.
  */
 void ceph_queue_caps_release(struct inode *inode)
 {
        struct ceph_inode_info *ci = ceph_inode(inode);
        struct rb_node *p;
 
+       /* lock i_ceph_lock, because ceph_d_revalidate(..., LOOKUP_RCU)
+        * may call __ceph_caps_issued_mask() on a freeing inode. */
+       spin_lock(&ci->i_ceph_lock);
        p = rb_first(&ci->i_caps);
        while (p) {
                struct ceph_cap *cap = rb_entry(p, struct ceph_cap, ci_node);
                p = rb_next(p);
                __ceph_remove_cap(cap, true);
        }
+       spin_unlock(&ci->i_ceph_lock);
 }
 
 /*