fs/9p: Workaround vfs rename rehash bug

This is similar to what ceph, ocfs2 and nfs does
http://kerneltrap.org/mailarchive/linux-fsdevel/2008/4/18/1498534

May be we should get vfs fixed
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NVenkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: NEric Van Hensbergen <ericvh@gmail.com>

fs/9p/vfs_inode.c

@@ -884,6 +884,11 @@ v9fs_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 				clear_nlink(new_inode);
 			else
 				drop_nlink(new_inode);
+			/*
+			 * Work around vfs rename rehash bug with
+			 * FS_RENAME_DOES_D_MOVE
+			 */
+			v9fs_invalidate_inode_attr(new_inode);
 		}
 		if (S_ISDIR(old_inode->i_mode)) {
 			if (!new_inode)