NTFS: Fix a potential bug in fs/ntfs/mft.c::map_extent_mft_record() that

      could occur in the future for when we start closing/freeing extent
      inodes if we don't set base_ni->ext.extent_ntfs_inos to NULL after
      we free it.
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

fs/ntfs/mft.c

@@ -418,7 +418,8 @@ MFT_RECORD *map_extent_mft_record(ntfs_inode *base_ni, MFT_REF mref,
 			m = ERR_PTR(-ENOMEM);
 			goto unm_err_out;
 		}
-		if (base_ni->ext.extent_ntfs_inos) {
+		if (base_ni->nr_extents) {
+			BUG_ON(!base_ni->ext.extent_ntfs_inos);
 			memcpy(tmp, base_ni->ext.extent_ntfs_inos, new_size -
 					4 * sizeof(ntfs_inode *));
 			kfree(base_ni->ext.extent_ntfs_inos);