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dm_target_zero.c revision 1.4 
      1 /*        $NetBSD: dm_target_zero.c,v 1.4 2008/12/21 00:59:39 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, NULL);
     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 			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 		strlcpy(dmt->name, "zero", DM_MAX_TYPE_NAME);
     74 		dmt->init = &dm_target_zero_init;
     75 		dmt->status = &dm_target_zero_status;
     76 		dmt->strategy = &dm_target_zero_strategy;
     77 		dmt->deps = &dm_target_zero_deps;
     78 		dmt->destroy = &dm_target_zero_destroy;
     79 		dmt->upcall = &dm_target_zero_upcall;
     80 
     81 		r = dm_target_insert(dmt);
     82 		break;
     83 
     84 	case MODULE_CMD_FINI:
     85 		r = dm_target_rem("zero");
     86 		break;
     87 
     88 	case MODULE_CMD_STAT:
     89 		return ENOTTY;
     90 
     91 	default:
     92 		return ENOTTY;
     93 	}
     94 
     95 	return r;
     96 }
     97 
     98 #endif
     99 
    100 /*
    101  * Zero target init function. This target doesn't need
    102  * target specific config area.
    103  */
    104 int
    105 dm_target_zero_init(dm_dev_t *dmv, void **target_config, char *argv)
    106 {
    107 
    108 	printf("Zero target init function called!!\n");
    109 
    110 	dmv->dev_type = DM_ZERO_DEV;
    111 
    112 	*target_config = NULL;
    113 
    114 	return 0;
    115 }
    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 
    143 /* Doesn't not need to do anything here. */
    144 int
    145 dm_target_zero_destroy(dm_table_entry_t *table_en)
    146 {
    147 	table_en->target_config = NULL;
    148 
    149 	/* Unbusy target so we can unload it */
    150 	dm_target_unbusy(table_en->target);
    151 
    152 	return 0;
    153 }
    154 
    155 /* Doesn't not need to do anything here. */
    156 int
    157 dm_target_zero_deps(dm_table_entry_t *table_en, prop_array_t prop_array)
    158 {
    159 	return 0;
    160 }
    161 
    162 /* Unsuported for this target. */
    163 int
    164 dm_target_zero_upcall(dm_table_entry_t *table_en, struct buf *bp)
    165 {
    166 	return 0;
    167 }
    168 
    169