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dm_target_zero.c revision 1.10.4.1 
      1 /*        $NetBSD: dm_target_zero.c,v 1.10.4.1 2010/05/30 05:17:20 rmind 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 /* dm_target_zero.c */
     44 int dm_target_zero_init(dm_dev_t *, void**,  char *);
     45 char * dm_target_zero_status(void *);
     46 int dm_target_zero_strategy(dm_table_entry_t *, struct buf *);
     47 int dm_target_zero_sync(dm_table_entry_t *);
     48 int dm_target_zero_destroy(dm_table_entry_t *);
     49 int dm_target_zero_deps(dm_table_entry_t *, prop_array_t);
     50 int dm_target_zero_upcall(dm_table_entry_t *, struct buf *);
     51 
     52 #ifdef DM_TARGET_MODULE
     53 /*
     54  * Every target can be compiled directly to dm driver or as a
     55  * separate module this part of target is used for loading targets
     56  * to dm driver.
     57  * Target can be unloaded from kernel only if there are no users of
     58  * it e.g. there are no devices which uses that target.
     59  */
     60 #include <sys/kernel.h>
     61 #include <sys/module.h>
     62 
     63 MODULE(MODULE_CLASS_MISC, dm_target_zero, "dm");
     64 
     65 static int
     66 dm_target_zero_modcmd(modcmd_t cmd, void *arg)
     67 {
     68 	dm_target_t *dmt;
     69 	int r;
     70 	dmt = NULL;
     71 
     72 	switch (cmd) {
     73 	case MODULE_CMD_INIT:
     74 		if ((dmt = dm_target_lookup("zero")) != NULL) {
     75 			dm_target_unbusy(dmt);
     76 			return EEXIST;
     77 		}
     78 		dmt = dm_target_alloc("zero");
     79 
     80 		dmt->version[0] = 1;
     81 		dmt->version[1] = 0;
     82 		dmt->version[2] = 0;
     83 		strlcpy(dmt->name, "zero", DM_MAX_TYPE_NAME);
     84 		dmt->init = &dm_target_zero_init;
     85 		dmt->status = &dm_target_zero_status;
     86 		dmt->strategy = &dm_target_zero_strategy;
     87 		dmt->sync = &dm_target_zero_sync;
     88 		dmt->deps = &dm_target_zero_deps;
     89 		dmt->destroy = &dm_target_zero_destroy;
     90 		dmt->upcall = &dm_target_zero_upcall;
     91 
     92 		r = dm_target_insert(dmt);
     93 		break;
     94 
     95 	case MODULE_CMD_FINI:
     96 		r = dm_target_rem("zero");
     97 
     98 		break;
     99 
    100 	case MODULE_CMD_STAT:
    101 		return ENOTTY;
    102 
    103 	default:
    104 		return ENOTTY;
    105 	}
    106 
    107 	return r;
    108 }
    109 #endif
    110 
    111 /*
    112  * Zero target init function. This target doesn't need
    113  * target specific config area.
    114  */
    115 int
    116 dm_target_zero_init(dm_dev_t * dmv, void **target_config, char *argv)
    117 {
    118 
    119 	printf("Zero target init function called!!\n");
    120 
    121 	dmv->dev_type = DM_ZERO_DEV;
    122 
    123 	*target_config = NULL;
    124 
    125 	return 0;
    126 }
    127 /* Status routine called to get params string. */
    128 char *
    129 dm_target_zero_status(void *target_config)
    130 {
    131 	return NULL;
    132 }
    133 
    134 
    135 /*
    136  * This routine does IO operations.
    137  */
    138 int
    139 dm_target_zero_strategy(dm_table_entry_t * table_en, struct buf * bp)
    140 {
    141 
    142 	/* printf("Zero target read function called %d!!\n", bp->b_bcount); */
    143 
    144 	memset(bp->b_data, 0, bp->b_bcount);
    145 	bp->b_resid = 0;	/* nestiobuf_done wants b_resid = 0 to be sure
    146 				 * that there is no other io to done  */
    147 
    148 	biodone(bp);
    149 
    150 	return 0;
    151 }
    152 /* Sync underlying disk caches. */
    153 int
    154 dm_target_zero_sync(dm_table_entry_t * table_en)
    155 {
    156 
    157 	return 0;
    158 }
    159 /* Doesn't not need to do anything here. */
    160 int
    161 dm_target_zero_destroy(dm_table_entry_t * table_en)
    162 {
    163 	table_en->target_config = NULL;
    164 
    165 	/* Unbusy target so we can unload it */
    166 	dm_target_unbusy(table_en->target);
    167 
    168 	return 0;
    169 }
    170 /* Doesn't not need to do anything here. */
    171 int
    172 dm_target_zero_deps(dm_table_entry_t * table_en, prop_array_t prop_array)
    173 {
    174 	return 0;
    175 }
    176 /* Unsuported for this target. */
    177 int
    178 dm_target_zero_upcall(dm_table_entry_t * table_en, struct buf * bp)
    179 {
    180 	return 0;
    181 }
    182