xref: /titanic_41/usr/src/uts/common/fs/zfs/vdev_missing.c (revision fcf3ce441efd61da9bb2884968af01cb7c1452cc)
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 };
86