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      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 #pragma ident	"%Z%%M%	%I%	%E% SMI"
     27 
     28 #include <sys/zfs_context.h>
     29 #include <sys/spa.h>
     30 #include <sys/vdev_impl.h>
     31 #include <sys/zio.h>
     32 #include <sys/fs/zfs.h>
     33 
     34 /*
     35  * Virtual device vector for the pool's root vdev.
     36  */
     37 
     38 /*
     39  * We should be able to tolerate one failure with absolutely no damage
     40  * to our metadata.  Two failures will take out space maps, a bunch of
     41  * indirect block trees, meta dnodes, dnodes, etc.  Probably not a happy
     42  * place to live.  When we get smarter, we can liberalize this policy.
     43  * e.g. If we haven't lost two consecutive top-level vdevs, then we are
     44  * probably fine.  Adding bean counters during alloc/free can make this
     45  * future guesswork more accurate.
     46  */
     47 static int
     48 too_many_errors(vdev_t *vd, int numerrors)
     49 {
     50 	ASSERT3U(numerrors, <=, vd->vdev_children);
     51 	return (numerrors > 0);
     52 }
     53 
     54 static int
     55 vdev_root_open(vdev_t *vd, uint64_t *asize, uint64_t *ashift)
     56 {
     57 	int c;
     58 	int lasterror = 0;
     59 	int numerrors = 0;
     60 
     61 	if (vd->vdev_children == 0) {
     62 		vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
     63 		return (EINVAL);
     64 	}
     65 
     66 	for (c = 0; c < vd->vdev_children; c++) {
     67 		vdev_t *cvd = vd->vdev_child[c];
     68 		int error;
     69 
     70 		if ((error = vdev_open(cvd)) != 0 &&
     71 		    !cvd->vdev_islog) {
     72 			lasterror = error;
     73 			numerrors++;
     74 			continue;
     75 		}
     76 	}
     77 
     78 	if (too_many_errors(vd, numerrors)) {
     79 		vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
     80 		return (lasterror);
     81 	}
     82 
     83 	*asize = 0;
     84 	*ashift = 0;
     85 
     86 	return (0);
     87 }
     88 
     89 static void
     90 vdev_root_close(vdev_t *vd)
     91 {
     92 	int c;
     93 
     94 	for (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 	NULL,
    115 	vdev_default_asize,
    116 	NULL,			/* io_start - not applicable to the root */
    117 	NULL,			/* io_done - not applicable to the root */
    118 	vdev_root_state_change,
    119 	VDEV_TYPE_ROOT,		/* name of this vdev type */
    120 	B_FALSE			/* not a leaf vdev */
    121 };
    122