zfs/lib/libzpool/vdev_missing.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 /*
  27  * The 'missing' vdev is a special vdev type used only during import.  It
  28  * signifies a placeholder in the root vdev for some vdev that we know is
  29  * missing.  We pass it down to the kernel to allow the rest of the
  30  * configuration to parsed and an attempt made to open all available devices.
  31  * Because its GUID is always 0, we know that the guid sum will mismatch and we
  32  * won't be able to open the pool anyway.
  33  */
  34
  35 #include <sys/zfs_context.h>
  36 #include <sys/spa.h>
  37 #include <sys/vdev_impl.h>
  38 #include <sys/fs/zfs.h>
  39 #include <sys/zio.h>
  40
  41 /* ARGSUSED */
  42 static int
  43 vdev_missing_open(vdev_t *vd, uint64_t *psize, uint64_t *ashift)
  44 {
  45         /*
  46          * Really this should just fail.  But then the root vdev will be in the
  47          * faulted state with VDEV_AUX_NO_REPLICAS, when what we really want is
  48          * VDEV_AUX_BAD_GUID_SUM.  So we pretend to succeed, knowing that we
  49          * will fail the GUID sum check before ever trying to open the pool.
  50          */
  51         *psize = SPA_MINDEVSIZE;
  52         *ashift = SPA_MINBLOCKSHIFT;
  53         return (0);
  54 }
  55
  56 /* ARGSUSED */
  57 static void
  58 vdev_missing_close(vdev_t *vd)
  59 {
  60 }
  61
  62 /* ARGSUSED */
  63 static int
  64 vdev_missing_io_start(zio_t *zio)
  65 {
  66         zio->io_error = ENOTSUP;
  67         return (ZIO_PIPELINE_CONTINUE);
  68 }
  69
  70 /* ARGSUSED */
  71 static void
  72 vdev_missing_io_done(zio_t *zio)
  73 {
  74 }
  75
  76 vdev_ops_t vdev_missing_ops = {
  77         vdev_missing_open,
  78         vdev_missing_close,
  79         vdev_default_asize,
  80         vdev_missing_io_start,
  81         vdev_missing_io_done,
  82         NULL,
  83         VDEV_TYPE_MISSING,      /* name of this vdev type */
  84         B_TRUE                  /* leaf vdev */
  85 };