sys/dev/dm/dm_target_zero.c

   1 /*        $NetBSD: dm_target_zero.c,v 1.9 2009/12/01 23:12:10 haad 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
  32
  33 /*
  34  * This file implements initial version of device-mapper zero target.
  35  */
  36 #include <sys/types.h>
  37 #include <sys/param.h>
  38
  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
  57 dm_target_zero_modcmd(modcmd_t cmd, void *arg)
  58 {
  59         dm_target_t *dmt;
  60         int r;
  61         dmt = NULL;
  62
  63         switch (cmd) {
  64         case MODULE_CMD_INIT:
  65                 if ((dmt = dm_target_lookup("zero")) != NULL) {
  66                         dm_target_unbusy(dmt);
  67                         return EEXIST;
  68                 }
  69                 dmt = dm_target_alloc("zero");
  70
  71                 dmt->version[0] = 1;
  72                 dmt->version[1] = 0;
  73                 dmt->version[2] = 0;
  74                 strlcpy(dmt->name, "zero", DM_MAX_TYPE_NAME);
  75                 dmt->init = &dm_target_zero_init;
  76                 dmt->status = &dm_target_zero_status;
  77                 dmt->strategy = &dm_target_zero_strategy;
  78                 dmt->deps = &dm_target_zero_deps;
  79                 dmt->destroy = &dm_target_zero_destroy;
  80                 dmt->upcall = &dm_target_zero_upcall;
  81
  82                 r = dm_target_insert(dmt);
  83                 break;
  84
  85         case MODULE_CMD_FINI:
  86                 r = dm_target_rem("zero");
  87
  88                 break;
  89
  90         case MODULE_CMD_STAT:
  91                 return ENOTTY;
  92
  93         default:
  94                 return ENOTTY;
  95         }
  96
  97         return r;
  98 }
  99 #endif
 100
 101 /*
 102  * Zero target init function. This target doesn't need
 103  * target specific config area.
 104  */
 105 int
 106 dm_target_zero_init(dm_dev_t * dmv, void **target_config, char *argv)
 107 {
 108
 109         printf("Zero target init function called!!\n");
 110
 111         dmv->dev_type = DM_ZERO_DEV;
 112
 113         *target_config = NULL;
 114
 115         return 0;
 116 }
 117 /* Status routine called to get params string. */
 118 char *
 119 dm_target_zero_status(void *target_config)
 120 {
 121         return NULL;
 122 }
 123
 124
 125 /*
 126  * This routine does IO operations.
 127  */
 128 int
 129 dm_target_zero_strategy(dm_table_entry_t * table_en, struct buf * bp)
 130 {
 131
 132         /* printf("Zero target read function called %d!!\n", bp->b_bcount); */
 133
 134         memset(bp->b_data, 0, bp->b_bcount);
 135         bp->b_resid = 0;        /* nestiobuf_done wants b_resid = 0 to be sure
 136                                  * that there is no other io to done  */
 137
 138         biodone(bp);
 139
 140         return 0;
 141 }
 142 /* Doesn't not need to do anything here. */
 143 int
 144 dm_target_zero_destroy(dm_table_entry_t * table_en)
 145 {
 146         table_en->target_config = NULL;
 147
 148         /* Unbusy target so we can unload it */
 149         dm_target_unbusy(table_en->target);
 150
 151         return 0;
 152 }
 153 /* Doesn't not need to do anything here. */
 154 int
 155 dm_target_zero_deps(dm_table_entry_t * table_en, prop_array_t prop_array)
 156 {
 157         return 0;
 158 }
 159 /* Unsuported for this target. */
 160 int
 161 dm_target_zero_upcall(dm_table_entry_t * table_en, struct buf * bp)
 162 {
 163         return 0;
 164 }