module/zfs/vdev_root.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) 2013 by Delphix. All rights reserved.
  28  */
  29
  30 #include <sys/zfs_context.h>
  31 #include <sys/spa.h>
  32 #include <sys/vdev_impl.h>
  33 #include <sys/zio.h>
  34 #include <sys/fs/zfs.h>
  35
  36 /*
  37  * Virtual device vector for the pool's root vdev.
  38  */
  39
  40 /*
  41  * We should be able to tolerate one failure with absolutely no damage
  42  * to our metadata.  Two failures will take out space maps, a bunch of
  43  * indirect block trees, meta dnodes, dnodes, etc.  Probably not a happy
  44  * place to live.  When we get smarter, we can liberalize this policy.
  45  * e.g. If we haven't lost two consecutive top-level vdevs, then we are
  46  * probably fine.  Adding bean counters during alloc/free can make this
  47  * future guesswork more accurate.
  48  */
  49 static int
  50 too_many_errors(vdev_t *vd, int numerrors)
  51 {
  52         ASSERT3U(numerrors, <=, vd->vdev_children);
  53         return (numerrors > 0);
  54 }
  55
  56 static int
  57 vdev_root_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
  58     uint64_t *ashift)
  59 {
  60         int lasterror = 0;
  61         int numerrors = 0;
  62
  63         if (vd->vdev_children == 0) {
  64                 vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
  65                 return (SET_ERROR(EINVAL));
  66         }
  67
  68         vdev_open_children(vd);
  69
  70         for (int c = 0; c < vd->vdev_children; c++) {
  71                 vdev_t *cvd = vd->vdev_child[c];
  72
  73                 if (cvd->vdev_open_error && !cvd->vdev_islog) {
  74                         lasterror = cvd->vdev_open_error;
  75                         numerrors++;
  76                 }
  77         }
  78
  79         if (too_many_errors(vd, numerrors)) {
  80                 vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
  81                 return (lasterror);
  82         }
  83
  84         *asize = 0;
  85         *max_asize = 0;
  86         *ashift = 0;
  87
  88         return (0);
  89 }
  90
  91 static void
  92 vdev_root_close(vdev_t *vd)
  93 {
  94         for (int c = 0; c < vd->vdev_children; c++)
  95                 vdev_close(vd->vdev_child[c]);
  96 }
  97
  98 static void
  99 vdev_root_state_change(vdev_t *vd, int faulted, int degraded)
 100 {
 101         if (too_many_errors(vd, faulted)) {
 102                 vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
 103                     VDEV_AUX_NO_REPLICAS);
 104         } else if (degraded) {
 105                 vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
 106         } else {
 107                 vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
 108         }
 109 }
 110
 111 vdev_ops_t vdev_root_ops = {
 112         vdev_root_open,
 113         vdev_root_close,
 114         vdev_default_asize,
 115         NULL,                   /* io_start - not applicable to the root */
 116         NULL,                   /* io_done - not applicable to the root */
 117         vdev_root_state_change,
 118         NULL,
 119         NULL,
 120         NULL,
 121         VDEV_TYPE_ROOT,         /* name of this vdev type */
 122         B_FALSE                 /* not a leaf vdev */
 123 };