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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 2009 Sun Microsystems, Inc.  All rights reserved.
     23  * Use is subject to license terms.
     24  */
     25 
     26 #include <sys/zfs_context.h>
     27 #include <sys/spa.h>
     28 #include <sys/vdev_impl.h>
     29 #include <sys/zio.h>
     30 #include <sys/fs/zfs.h>
     31 
     32 /*
     33  * Virtual device vector for the pool's root vdev.
     34  */
     35 
     36 /*
     37  * We should be able to tolerate one failure with absolutely no damage
     38  * to our metadata.  Two failures will take out space maps, a bunch of
     39  * indirect block trees, meta dnodes, dnodes, etc.  Probably not a happy
     40  * place to live.  When we get smarter, we can liberalize this policy.
     41  * e.g. If we haven't lost two consecutive top-level vdevs, then we are
     42  * probably fine.  Adding bean counters during alloc/free can make this
     43  * future guesswork more accurate.
     44  */
     45 static int
     46 too_many_errors(vdev_t *vd, int numerrors)
     47 {
     48 	ASSERT3U(numerrors, <=, vd->vdev_children);
     49 	return (numerrors > 0);
     50 }
     51 
     52 static int
     53 vdev_root_open(vdev_t *vd, uint64_t *asize, uint64_t *ashift)
     54 {
     55 	int lasterror = 0;
     56 	int numerrors = 0;
     57 
     58 	if (vd->vdev_children == 0) {
     59 		vd->vdev_stat.vs_aux = VDEV_AUX_BAD_LABEL;
     60 		return (EINVAL);
     61 	}
     62 
     63 	vdev_open_children(vd);
     64 
     65 	for (int c = 0; c < vd->vdev_children; c++) {
     66 		vdev_t *cvd = vd->vdev_child[c];
     67 
     68 		if (cvd->vdev_open_error && !cvd->vdev_islog) {
     69 			lasterror = cvd->vdev_open_error;
     70 			numerrors++;
     71 		}
     72 	}
     73 
     74 	if (too_many_errors(vd, numerrors)) {
     75 		vd->vdev_stat.vs_aux = VDEV_AUX_NO_REPLICAS;
     76 		return (lasterror);
     77 	}
     78 
     79 	*asize = 0;
     80 	*ashift = 0;
     81 
     82 	return (0);
     83 }
     84 
     85 static void
     86 vdev_root_close(vdev_t *vd)
     87 {
     88 	for (int c = 0; c < vd->vdev_children; c++)
     89 		vdev_close(vd->vdev_child[c]);
     90 }
     91 
     92 static void
     93 vdev_root_state_change(vdev_t *vd, int faulted, int degraded)
     94 {
     95 	if (too_many_errors(vd, faulted)) {
     96 		vdev_set_state(vd, B_FALSE, VDEV_STATE_CANT_OPEN,
     97 		    VDEV_AUX_NO_REPLICAS);
     98 	} else if (degraded) {
     99 		vdev_set_state(vd, B_FALSE, VDEV_STATE_DEGRADED, VDEV_AUX_NONE);
    100 	} else {
    101 		vdev_set_state(vd, B_FALSE, VDEV_STATE_HEALTHY, VDEV_AUX_NONE);
    102 	}
    103 }
    104 
    105 vdev_ops_t vdev_root_ops = {
    106 	vdev_root_open,
    107 	vdev_root_close,
    108 	vdev_default_asize,
    109 	NULL,			/* io_start - not applicable to the root */
    110 	NULL,			/* io_done - not applicable to the root */
    111 	vdev_root_state_change,
    112 	VDEV_TYPE_ROOT,		/* name of this vdev type */
    113 	B_FALSE			/* not a leaf vdev */
    114 };
    115