1 /* $NetBSD: dm_target_zero.c,v 1.10 2010/01/04 00:12:22 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 * This file implements initial version of device-mapper zero target. 34 */ 35 #include <dev/disk/dm/dm.h> 36 37 /* 38 * This routine does IO operations. 39 */ 40 static int 41 dm_target_zero_strategy(dm_table_entry_t *table_en, struct buf *bp) 42 { 43 memset(bp->b_data, 0, bp->b_bcount); 44 bp->b_resid = 0; 45 biodone(&bp->b_bio1); 46 47 return 0; 48 } 49 50 static int 51 dmtz_mod_handler(module_t mod, int type, void *unused) 52 { 53 dm_target_t *dmt = NULL; 54 int err = 0; 55 56 switch(type) { 57 case MOD_LOAD: 58 if ((dmt = dm_target_lookup("zero")) != NULL) { 59 dm_target_unbusy(dmt); 60 return EEXIST; 61 } 62 dmt = dm_target_alloc("zero"); 63 dmt->version[0] = 1; 64 dmt->version[1] = 0; 65 dmt->version[2] = 0; 66 dmt->strategy = &dm_target_zero_strategy; 67 68 err = dm_target_insert(dmt); 69 if (err == 0) 70 kprintf("dm_target_zero: Successfully initialized\n"); 71 break; 72 73 case MOD_UNLOAD: 74 err = dm_target_remove("zero"); 75 if (err == 0) 76 kprintf("dm_target_zero: unloaded\n"); 77 break; 78 } 79 80 return err; 81 } 82 83 DM_TARGET_BUILTIN(dm_target_zero, dmtz_mod_handler); 84