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dm_target_zero.c revision 1.21 
      1 /*        $NetBSD: dm_target_zero.c,v 1.21 2019/12/12 16:28:24 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 1.21 2019/12/12 16:28:24 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_status(void *);
     47 int dm_target_zero_strategy(dm_table_entry_t *, struct buf *);
     48 int dm_target_zero_sync(dm_table_entry_t *);
     49 int dm_target_zero_destroy(dm_table_entry_t *);
     50 int dm_target_zero_deps(dm_table_entry_t *, prop_array_t);
     51 int dm_target_zero_upcall(dm_table_entry_t *, struct buf *);
     52 
     53 #ifdef DM_TARGET_MODULE
     54 /*
     55  * Every target can be compiled directly to dm driver or as a
     56  * separate module this part of target is used for loading targets
     57  * to dm driver.
     58  * Target can be unloaded from kernel only if there are no users of
     59  * it e.g. there are no devices which uses that target.
     60  */
     61 #include <sys/kernel.h>
     62 #include <sys/module.h>
     63 
     64 MODULE(MODULE_CLASS_MISC, dm_target_zero, "dm");
     65 
     66 static int
     67 dm_target_zero_modcmd(modcmd_t cmd, void *arg)
     68 {
     69 	dm_target_t *dmt;
     70 	int r;
     71 	dmt = NULL;
     72 
     73 	switch (cmd) {
     74 	case MODULE_CMD_INIT:
     75 		if ((dmt = dm_target_lookup("zero")) != NULL) {
     76 			dm_target_unbusy(dmt);
     77 			return EEXIST;
     78 		}
     79 		dmt = dm_target_alloc("zero");
     80 
     81 		dmt->version[0] = 1;
     82 		dmt->version[1] = 0;
     83 		dmt->version[2] = 0;
     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 		dmt->secsize = dm_target_dummy_secsize;
     92 
     93 		r = dm_target_insert(dmt);
     94 		break;
     95 
     96 	case MODULE_CMD_FINI:
     97 		r = dm_target_rem("zero");
     98 
     99 		break;
    100 
    101 	case MODULE_CMD_STAT:
    102 		return ENOTTY;
    103 
    104 	default:
    105 		return ENOTTY;
    106 	}
    107 
    108 	return r;
    109 }
    110 #endif
    111 
    112 /*
    113  * Zero target init function. This target doesn't need
    114  * target specific config area.
    115  */
    116 int
    117 dm_target_zero_init(dm_table_entry_t *table_en, int argc, char **argv)
    118 {
    119 
    120 	printf("Zero target init function called!!\n");
    121 
    122 	table_en->target_config = NULL;
    123 
    124 	return 0;
    125 }
    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 
    153 /* Sync underlying disk caches. */
    154 int
    155 dm_target_zero_sync(dm_table_entry_t *table_en)
    156 {
    157 
    158 	return 0;
    159 }
    160 
    161 /* Does not need to do anything here. */
    162 int
    163 dm_target_zero_destroy(dm_table_entry_t *table_en)
    164 {
    165 	/* Unbusy target so we can unload it */
    166 	dm_target_unbusy(table_en->target);
    167 
    168 	return 0;
    169 }
    170 
    171 /* Does not need to do anything here. */
    172 int
    173 dm_target_zero_deps(dm_table_entry_t *table_en, prop_array_t prop_array)
    174 {
    175 	return 0;
    176 }
    177 
    178 /* Unsuported for this target. */
    179 int
    180 dm_target_zero_upcall(dm_table_entry_t *table_en, struct buf *bp)
    181 {
    182 	return 0;
    183 }
    184