ceph: initialize root dentry

Set up d_fsdata on the root dentry.  This fixes a NULL pointer dereference
in ceph_d_prune on umount.  It also means we can eventually strip out all
of the conditional checks on d_fsdata because it is now set unconditionally
(prior to setting up the d_ops).

Fix the ceph_d_prune debug print while we're here.

Signed-off-by: Sage Weil <sage@newdream.net>

2 files changed, 5 insertions, 3 deletions

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index 2abd0dfad7f8..bca3948e9dbf 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1143,7 +1143,7 @@ static void ceph_d_prune(struct dentry *dentry)
 {
         struct ceph_dentry_info *di;
 
-        dout("d_release %p\n", dentry);
+        dout("ceph_d_prune %p\n", dentry);
 
         /* do we have a valid parent? */
         if (!dentry->d_parent || IS_ROOT(dentry))
diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index a90846fac759..8dc73a594a90 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -638,10 +638,12 @@ static struct dentry *open_root_dentry(struct ceph_fs_client *fsc,
         if (err == 0) {
                 dout("open_root_inode success\n");
                 if (ceph_ino(req->r_target_inode) == CEPH_INO_ROOT &&
-                    fsc->sb->s_root == NULL)
+                    fsc->sb->s_root == NULL) {
                         root = d_alloc_root(req->r_target_inode);
-                else
+                        ceph_init_dentry(root);
+                } else {
                         root = d_obtain_alias(req->r_target_inode);
+                }
                 req->r_target_inode = NULL;
                 dout("open_root_inode success, root dentry is %p\n", root);
         } else {