Revert "ceph: keep reference to parent inode on ceph_dentry"

This reverts commit 97d79b40.

This fails to account for d_parent changes due to rename or disconnected
dentries due to submounts or NFS reexports.
Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/dir.c

@@ -60,7 +60,6 @@ int ceph_init_dentry(struct dentry *dentry)
 	}
 	di->dentry = dentry;
 	di->lease_session = NULL;
-	di->parent_inode = igrab(dentry->d_parent->d_inode);
 	dentry->d_fsdata = di;
 	dentry->d_time = jiffies;
 	ceph_dentry_lru_add(dentry);
@@ -1034,7 +1033,7 @@ static void ceph_dentry_release(struct dentry *dentry)
 	u64 snapid = CEPH_NOSNAP;
 
 	if (!IS_ROOT(dentry)) {
-		parent_inode = di->parent_inode;
+		parent_inode = dentry->d_parent->d_inode;
 		if (parent_inode)
 			snapid = ceph_snap(parent_inode);
 	}
@@ -1059,8 +1058,6 @@ static void ceph_dentry_release(struct dentry *dentry)
 		kmem_cache_free(ceph_dentry_cachep, di);
 		dentry->d_fsdata = NULL;
 	}
-	if (parent_inode)
-		iput(parent_inode);
 }
 
 static int ceph_snapdir_d_revalidate(struct dentry *dentry,

fs/ceph/super.h

@@ -207,7 +207,6 @@ struct ceph_dentry_info {
 	struct dentry *dentry;
 	u64 time;
 	u64 offset;
-	struct inode *parent_inode;
 };
 
 struct ceph_inode_xattrs_info {