Home | History | Annotate | Line # | Download | only in dm 
      1 /*        $NetBSD: dm_target_zero.c,v 1.32 2020/01/21 16:27:53 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 1.32 2020/01/21 16:27:53 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 #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 
     62 	switch (cmd) {
     63 	case MODULE_CMD_INIT:
     64 		if ((dmt = dm_target_lookup("zero")) != NULL) {
     65 			dm_target_unbusy(dmt);
     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 		dmt->init = &dm_target_zero_init;
     74 		dmt->strategy = &dm_target_zero_strategy;
     75 		dmt->destroy = &dm_target_zero_destroy;
     76 		//dmt->upcall = &dm_target_zero_upcall;
     77 
     78 		r = dm_target_insert(dmt);
     79 		break;
     80 
     81 	case MODULE_CMD_FINI:
     82 		r = dm_target_rem("zero");
     83 
     84 		break;
     85 
     86 	case MODULE_CMD_STAT:
     87 		return ENOTTY;
     88 
     89 	default:
     90 		return ENOTTY;
     91 	}
     92 
     93 	return r;
     94 }
     95 #endif
     96 
     97 /*
     98  * Zero target init function. This target doesn't need
     99  * target specific config area.
    100  */
    101 int
    102 dm_target_zero_init(dm_table_entry_t *table_en, int argc, char **argv)
    103 {
    104 
    105 	if (argc != 0) {
    106 		printf("Zero target takes 0 args, %d given\n", argc);
    107 		return EINVAL;
    108 	}
    109 
    110 	printf("Zero target init function called!!\n");
    111 
    112 	table_en->target_config = NULL;
    113 
    114 	return 0;
    115 }
    116 
    117 /*
    118  * This routine does IO operations.
    119  */
    120 int
    121 dm_target_zero_strategy(dm_table_entry_t *table_en, struct buf *bp)
    122 {
    123 
    124 	memset(bp->b_data, 0, bp->b_bcount);
    125 	bp->b_resid = 0;	/* nestiobuf_done wants b_resid = 0 to be sure
    126 				 * that there is no other io to done  */
    127 	biodone(bp);
    128 
    129 	return 0;
    130 }
    131 
    132 /* Does not need to do anything here. */
    133 int
    134 dm_target_zero_destroy(dm_table_entry_t *table_en)
    135 {
    136 
    137 	/* Unbusy target so we can unload it */
    138 	dm_target_unbusy(table_en->target);
    139 
    140 	return 0;
    141 }
    142 
    143 #if 0
    144 /* Unsupported for this target. */
    145 int
    146 dm_target_zero_upcall(dm_table_entry_t *table_en, struct buf *bp)
    147 {
    148 
    149 	return 0;
    150 }
    151 #endif
    152