1 /* $NetBSD: dm_target_zero.c,v 1.32 2020/01/21 16:27:53 tkusumi Exp $ */
2
3 /*
4 * Copyright (c) 2008 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Adam Hamsik.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31 #include <sys/cdefs.h>
32 __KERNEL_RCSID(0, "$NetBSD: dm_target_zero.c,v 1.32 2020/01/21 16:27:53 tkusumi Exp $");
33
34 /*
35 * This file implements initial version of device-mapper zero target.
36 */
37 #include <sys/types.h>
38 #include <sys/param.h>
39 #include <sys/buf.h>
40
41 #include "dm.h"
42
43 #ifdef DM_TARGET_MODULE
44 /*
45 * Every target can be compiled directly to dm driver or as a
46 * separate module this part of target is used for loading targets
47 * to dm driver.
48 * Target can be unloaded from kernel only if there are no users of
49 * it e.g. there are no devices which uses that target.
50 */
51 #include <sys/kernel.h>
52 #include <sys/module.h>
53
54 MODULE(MODULE_CLASS_MISC, dm_target_zero, "dm");
55
56 static int
dm_target_zero_modcmd(modcmd_t cmd,void * arg)57 dm_target_zero_modcmd(modcmd_t cmd, void *arg)
58 {
59 dm_target_t *dmt;
60 int r;
61
62 switch (cmd) {
63 case MODULE_CMD_INIT:
64 if ((dmt = dm_target_lookup("zero")) != NULL) {
65 dm_target_unbusy(dmt);
66 return EEXIST;
67 }
68 dmt = dm_target_alloc("zero");
69
70 dmt->version[0] = 1;
71 dmt->version[1] = 0;
72 dmt->version[2] = 0;
73 dmt->init = &dm_target_zero_init;
74 dmt->strategy = &dm_target_zero_strategy;
75 dmt->destroy = &dm_target_zero_destroy;
76 //dmt->upcall = &dm_target_zero_upcall;
77
78 r = dm_target_insert(dmt);
79 break;
80
81 case MODULE_CMD_FINI:
82 r = dm_target_rem("zero");
83
84 break;
85
86 case MODULE_CMD_STAT:
87 return ENOTTY;
88
89 default:
90 return ENOTTY;
91 }
92
93 return r;
94 }
95 #endif
96
97 /*
98 * Zero target init function. This target doesn't need
99 * target specific config area.
100 */
101 int
dm_target_zero_init(dm_table_entry_t * table_en,int argc,char ** argv)102 dm_target_zero_init(dm_table_entry_t *table_en, int argc, char **argv)
103 {
104
105 if (argc != 0) {
106 printf("Zero target takes 0 args, %d given\n", argc);
107 return EINVAL;
108 }
109
110 printf("Zero target init function called!!\n");
111
112 table_en->target_config = NULL;
113
114 return 0;
115 }
116
117 /*
118 * This routine does IO operations.
119 */
120 int
dm_target_zero_strategy(dm_table_entry_t * table_en,struct buf * bp)121 dm_target_zero_strategy(dm_table_entry_t *table_en, struct buf *bp)
122 {
123
124 memset(bp->b_data, 0, bp->b_bcount);
125 bp->b_resid = 0; /* nestiobuf_done wants b_resid = 0 to be sure
126 * that there is no other io to done */
127 biodone(bp);
128
129 return 0;
130 }
131
132 /* Does not need to do anything here. */
133 int
dm_target_zero_destroy(dm_table_entry_t * table_en)134 dm_target_zero_destroy(dm_table_entry_t *table_en)
135 {
136
137 /* Unbusy target so we can unload it */
138 dm_target_unbusy(table_en->target);
139
140 return 0;
141 }
142
143 #if 0
144 /* Unsupported for this target. */
145 int
146 dm_target_zero_upcall(dm_table_entry_t *table_en, struct buf *bp)
147 {
148
149 return 0;
150 }
151 #endif
152