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dm_target_zero.c revision 1.25 
      1 /*        $NetBSD: dm_target_zero.c,v 1.25 2019/12/15 10:12:45 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 1.25 2019/12/15 10:12:45 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 
     40 #include <sys/buf.h>
     41 
     42 #include "dm.h"
     43 
     44 /* dm_target_zero.c */
     45 int dm_target_zero_init(dm_table_entry_t *, int, char **);
     46 char *dm_target_zero_table(void *);
     47 int dm_target_zero_strategy(dm_table_entry_t *, struct buf *);
     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 		dmt->init = &dm_target_zero_init;
     84 		dmt->table = &dm_target_zero_table;
     85 		dmt->strategy = &dm_target_zero_strategy;
     86 		dmt->deps = &dm_target_zero_deps;
     87 		dmt->destroy = &dm_target_zero_destroy;
     88 		dmt->upcall = &dm_target_zero_upcall;
     89 
     90 		r = dm_target_insert(dmt);
     91 		break;
     92 
     93 	case MODULE_CMD_FINI:
     94 		r = dm_target_rem("zero");
     95 
     96 		break;
     97 
     98 	case MODULE_CMD_STAT:
     99 		return ENOTTY;
    100 
    101 	default:
    102 		return ENOTTY;
    103 	}
    104 
    105 	return r;
    106 }
    107 #endif
    108 
    109 /*
    110  * Zero target init function. This target doesn't need
    111  * target specific config area.
    112  */
    113 int
    114 dm_target_zero_init(dm_table_entry_t *table_en, int argc, char **argv)
    115 {
    116 
    117 	printf("Zero target init function called!!\n");
    118 
    119 	table_en->target_config = NULL;
    120 
    121 	return 0;
    122 }
    123 
    124 /* Table routine called to get params string. */
    125 char *
    126 dm_target_zero_table(void *target_config)
    127 {
    128 	return NULL;
    129 }
    130 
    131 
    132 /*
    133  * This routine does IO operations.
    134  */
    135 int
    136 dm_target_zero_strategy(dm_table_entry_t *table_en, struct buf *bp)
    137 {
    138 
    139 	memset(bp->b_data, 0, bp->b_bcount);
    140 	bp->b_resid = 0;	/* nestiobuf_done wants b_resid = 0 to be sure
    141 				 * that there is no other io to done  */
    142 
    143 	biodone(bp);
    144 
    145 	return 0;
    146 }
    147 
    148 /* Does not need to do anything here. */
    149 int
    150 dm_target_zero_destroy(dm_table_entry_t *table_en)
    151 {
    152 	/* Unbusy target so we can unload it */
    153 	dm_target_unbusy(table_en->target);
    154 
    155 	return 0;
    156 }
    157 
    158 /* Does not need to do anything here. */
    159 int
    160 dm_target_zero_deps(dm_table_entry_t *table_en, prop_array_t prop_array)
    161 {
    162 	return 0;
    163 }
    164 
    165 /* Unsuported for this target. */
    166 int
    167 dm_target_zero_upcall(dm_table_entry_t *table_en, struct buf *bp)
    168 {
    169 	return 0;
    170 }
    171