[PATCH 6/8] ceph: use READ_ONCE to access d_parent in RCU critical section

[Yan, Zheng]

Signed-off-by: "Yan, Zheng" <z...@redhat.com>
---
 fs/ceph/mds_client.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 60e8ddbdfdc5..870754e9d572 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -913,7 +913,7 @@ static int __choose_mds(struct ceph_mds_client *mdsc,
                struct inode *dir;
 
                rcu_read_lock();
-               parent = req->r_dentry->d_parent;
+               parent = READ_ONCE(req->r_dentry->d_parent);
                dir = req->r_parent ? : d_inode_rcu(parent);
 
                if (!dir || dir->i_sb != mdsc->fsc->sb) {
@@ -2131,8 +2131,8 @@ char *ceph_mdsc_build_path(struct dentry *dentry, int 
*plen, u64 *pbase,
                if (inode && ceph_snap(inode) == CEPH_SNAPDIR) {
                        dout("build_path path+%d: %p SNAPDIR\n",
                             pos, temp);
-               } else if (stop_on_nosnap && inode && dentry != temp &&
-                          ceph_snap(inode) == CEPH_NOSNAP) {
+               } else if (stop_on_nosnap && dentry != temp &&
+                          inode && ceph_snap(inode) == CEPH_NOSNAP) {
                        spin_unlock(&temp->d_lock);
                        pos++; /* get rid of any prepended '/' */
                        break;
@@ -2145,7 +2145,7 @@ char *ceph_mdsc_build_path(struct dentry *dentry, int 
*plen, u64 *pbase,
                        memcpy(path + pos, temp->d_name.name, temp->d_name.len);
                }
                spin_unlock(&temp->d_lock);
-               temp = temp->d_parent;
+               temp = READ_ONCE(temp->d_parent);
 
                /* Are we at the root? */
                if (IS_ROOT(temp))
-- 
2.17.2