c7996ddf80
The gunion(8) utility is used to track changes to a read-only disk on a writable disk. Logically, a writable disk is placed over a read-only disk. Write requests are intercepted and stored on the writable disk. Read requests are first checked to see if they have been written on the top (writable disk) and if found are returned. If they have not been written on the top disk, then they are read from the lower disk. The gunion(8) utility can be especially useful if you have a large disk with a corrupted filesystem that you are unsure of how to repair. You can use gunion(8) to place another disk over the corrupted disk and then attempt to repair the filesystem. If the repair fails, you can revert all the changes in the upper disk and be back to the unchanged state of the lower disk thus allowing you to try another approach to repairing it. If the repair is successful you can commit all the writes recorded on the top disk to the lower disk. Another use of the gunion(8) utility is to try out upgrades to your system. Place the upper disk over the disk holding your filesystem that is to be upgraded and then run the upgrade on it. If it works, commit it; if it fails, revert the upgrade. Further details can be found in the gunion(8) manual page. Reviewed by: Chuck Silvers, kib (earlier version) tested by: Peter Holm Differential Revision: https://reviews.freebsd.org/D32697
84 lines
2.6 KiB
C
84 lines
2.6 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2022 Marshall Kirk McKusick <mckusick@mckusick.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include <libgeom.h>
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#include <geom/union/g_union.h>
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#include "core/geom.h"
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uint32_t lib_version = G_LIB_VERSION;
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uint32_t version = G_UNION_VERSION;
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struct g_command class_commands[] = {
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{ "create", G_FLAG_LOADKLD, NULL,
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{
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{ 'o', "offset", "0", G_TYPE_NUMBER },
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{ 's', "size", "0", G_TYPE_NUMBER },
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{ 'S', "secsize", "0", G_TYPE_NUMBER },
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{ 'v', "verbose", NULL, G_TYPE_BOOL },
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{ 'Z', "gunionname", G_VAL_OPTIONAL, G_TYPE_STRING },
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G_OPT_SENTINEL
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},
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"[-v] [-o offset] [-s size] [-S secsize] [-Z gunionname] "
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"upperdev lowerdev"
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},
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{ "destroy", 0, NULL,
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{
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{ 'f', "force", NULL, G_TYPE_BOOL },
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{ 'v', "verbose", NULL, G_TYPE_BOOL },
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G_OPT_SENTINEL
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},
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"[-fv] prov ..."
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},
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{ "reset", 0, NULL,
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{
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{ 'v', "verbose", NULL, G_TYPE_BOOL },
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G_OPT_SENTINEL
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},
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"[-v] prov ..."
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},
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{ "commit", 0, NULL,
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{
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{ 'f', "force", NULL, G_TYPE_BOOL },
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{ 'r', "reboot", NULL, G_TYPE_BOOL },
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{ 'v', "verbose", NULL, G_TYPE_BOOL },
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G_OPT_SENTINEL
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},
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"[-frv] prov ..."
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},
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{ "revert", 0, NULL,
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{
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{ 'v', "verbose", NULL, G_TYPE_BOOL },
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G_OPT_SENTINEL
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},
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"[-v] prov ..."
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},
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G_CMD_SENTINEL
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};
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