xfs: fix efi/efd error handling to avoid fs shutdown hangs

[Dan Carpenter]

Hello Brian Foster,

The patch 8d99fe92fed0: "xfs: fix efi/efd error handling to avoid fs
shutdown hangs" from Aug 19, 2015, leads to the following static
checker warning:

	fs/xfs/xfs_bmap_util.c:134 xfs_bmap_finish()
	warn: error is never (-117)

fs/xfs/xfs_bmap_util.c
   120          error = __xfs_trans_roll(tp, ip, &committed);

It used to be that error was set by xfs_free_extent() which does return
-EFSCORRUPTED.  But I don't think __xfs_trans_roll() can.

   121          if (error) {
   122                  /*
   123                   * If the transaction was committed, drop the EFD reference
   124                   * since we're bailing out of here. The other reference is
   125                   * dropped when the EFI hits the AIL.
   126                   *
   127                   * If the transaction was not committed, the EFI is freed by the
   128                   * EFI item unlock handler on abort. Also, we have a new
   129                   * transaction so we should return committed=1 even though we're
   130                   * returning an error.
   131                   */
   132                  if (committed) {
   133                          xfs_efi_release(efi);
   134                          xfs_force_shutdown((*tp)->t_mountp,
   135                                  (error == -EFSCORRUPTED) ?
   136                                          SHUTDOWN_CORRUPT_INCORE :
   137                                          SHUTDOWN_META_IO_ERROR);
   138                  }
   139                  return error;
   140          }

regards,
dan carpenter