module/zfs/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 2010 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 /*
  27  * Copyright (c) 2012, 2016 by Delphix. All rights reserved.
  28  */
  29
  30 /*
  31  * The 'missing' vdev is a special vdev type used only during import.  It
  32  * signifies a placeholder in the root vdev for some vdev that we know is
  33  * missing.  We pass it down to the kernel to allow the rest of the
  34  * configuration to parsed and an attempt made to open all available devices.
  35  * Because its GUID is always 0, we know that the guid sum will mismatch and we
  36  * won't be able to open the pool anyway.
  37  */
  38
  39 #include <sys/zfs_context.h>
  40 #include <sys/spa.h>
  41 #include <sys/vdev_impl.h>
  42 #include <sys/fs/zfs.h>
  43 #include <sys/zio.h>
  44
  45 /* ARGSUSED */
  46 static int
  47 vdev_missing_open(vdev_t *vd, uint64_t *psize, uint64_t *max_psize,
  48     uint64_t *ashift)
  49 {
  50         /*
  51          * Really this should just fail.  But then the root vdev will be in the
  52          * faulted state with VDEV_AUX_NO_REPLICAS, when what we really want is
  53          * VDEV_AUX_BAD_GUID_SUM.  So we pretend to succeed, knowing that we
  54          * will fail the GUID sum check before ever trying to open the pool.
  55          */
  56         *psize = 0;
  57         *max_psize = 0;
  58         *ashift = 0;
  59         return (0);
  60 }
  61
  62 /* ARGSUSED */
  63 static void
  64 vdev_missing_close(vdev_t *vd)
  65 {
  66 }
  67
  68 /* ARGSUSED */
  69 static void
  70 vdev_missing_io_start(zio_t *zio)
  71 {
  72         zio->io_error = SET_ERROR(ENOTSUP);
  73         zio_execute(zio);
  74 }
  75
  76 /* ARGSUSED */
  77 static void
  78 vdev_missing_io_done(zio_t *zio)
  79 {
  80 }
  81
  82 vdev_ops_t vdev_missing_ops = {
  83         vdev_missing_open,
  84         vdev_missing_close,
  85         vdev_default_asize,
  86         vdev_missing_io_start,
  87         vdev_missing_io_done,
  88         NULL,
  89         NULL,
  90         NULL,
  91         NULL,
  92         NULL,
  93         NULL,
  94         VDEV_TYPE_MISSING,      /* name of this vdev type */
  95         B_TRUE                  /* leaf vdev */
  96 };
  97
  98 vdev_ops_t vdev_hole_ops = {
  99         vdev_missing_open,
 100         vdev_missing_close,
 101         vdev_default_asize,
 102         vdev_missing_io_start,
 103         vdev_missing_io_done,
 104         NULL,
 105         NULL,
 106         NULL,
 107         NULL,
 108         NULL,
 109         NULL,
 110         VDEV_TYPE_HOLE,         /* name of this vdev type */
 111         B_TRUE                  /* leaf vdev */
 112 };