1 /* $NetBSD: dm_table.c,v 1.5 2010/01/04 00:19:08 haad Exp $ */ 2 3 /* 4 * Copyright (c) 2010-2011 Alex Hornung <alex@alexhornung.com> 5 * Copyright (c) 2008 The NetBSD Foundation, Inc. 6 * All rights reserved. 7 * 8 * This code is derived from software contributed to The NetBSD Foundation 9 * by Adam Hamsik. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 * POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 #include <sys/types.h> 34 #include <sys/param.h> 35 36 #include <sys/malloc.h> 37 38 #include <dev/disk/dm/dm.h> 39 40 /* 41 * There are two types of users of this interface: 42 * 43 * a) Readers such as 44 * dmstrategy, dmgetdisklabel, dmsize, dm_dev_status_ioctl, 45 * dm_table_deps_ioctl, dm_table_status_ioctl, dm_table_reload_ioctl 46 * 47 * b) Writers such as 48 * dm_dev_remove_ioctl, dm_dev_resume_ioctl, dm_table_clear_ioctl 49 * 50 * Writers can work with table_head only when there are no readers. We 51 * simply use shared/exclusive locking to ensure this. 52 */ 53 54 static int dm_table_busy(dm_table_head_t *, uint8_t); 55 static void dm_table_unbusy(dm_table_head_t *); 56 57 /* 58 * Function to increment table user reference counter. Return id 59 * of table_id table. 60 * DM_TABLE_ACTIVE will return active table id. 61 * DM_TABLE_INACTIVE will return inactive table id. 62 */ 63 static int 64 dm_table_busy(dm_table_head_t * head, uint8_t table_id) 65 { 66 uint8_t id; 67 68 id = 0; 69 70 lockmgr(&head->table_mtx, LK_SHARED); 71 72 if (table_id == DM_TABLE_ACTIVE) 73 id = head->cur_active_table; 74 else 75 id = 1 - head->cur_active_table; 76 77 atomic_add_int(&head->io_cnt, 1); 78 79 return id; 80 } 81 /* 82 * Function release table lock and eventually wakeup all waiters. 83 */ 84 static void 85 dm_table_unbusy(dm_table_head_t * head) 86 { 87 KKASSERT(head->io_cnt != 0); 88 89 atomic_subtract_int(&head->io_cnt, 1); 90 91 lockmgr(&head->table_mtx, LK_RELEASE); 92 } 93 /* 94 * Return current active table to caller, increment io_cnt reference counter. 95 */ 96 dm_table_t * 97 dm_table_get_entry(dm_table_head_t * head, uint8_t table_id) 98 { 99 uint8_t id; 100 101 id = dm_table_busy(head, table_id); 102 103 return &head->tables[id]; 104 } 105 /* 106 * Decrement io reference counter and release shared lock. 107 */ 108 void 109 dm_table_release(dm_table_head_t * head, uint8_t table_id) 110 { 111 dm_table_unbusy(head); 112 } 113 /* 114 * Switch table from inactive to active mode. Have to wait until io_cnt is 0. 115 */ 116 void 117 dm_table_switch_tables(dm_table_head_t * head) 118 { 119 lockmgr(&head->table_mtx, LK_EXCLUSIVE); 120 121 head->cur_active_table = 1 - head->cur_active_table; 122 123 lockmgr(&head->table_mtx, LK_RELEASE); 124 } 125 /* 126 * Destroy all table data. This function can run when there are no 127 * readers on table lists. 128 */ 129 int 130 dm_table_destroy(dm_table_head_t * head, uint8_t table_id) 131 { 132 dm_table_t *tbl; 133 dm_table_entry_t *table_en; 134 uint8_t id; 135 136 lockmgr(&head->table_mtx, LK_EXCLUSIVE); 137 138 aprint_debug("dm_Table_destroy called with %d--%d\n", table_id, head->io_cnt); 139 140 if (table_id == DM_TABLE_ACTIVE) 141 id = head->cur_active_table; 142 else 143 id = 1 - head->cur_active_table; 144 145 tbl = &head->tables[id]; 146 147 while (!SLIST_EMPTY(tbl)) { /* List Deletion. */ 148 table_en = SLIST_FIRST(tbl); 149 /* 150 * Remove target specific config data. After successfull 151 * call table_en->target_config must be set to NULL. 152 */ 153 table_en->target->destroy(table_en); 154 155 SLIST_REMOVE_HEAD(tbl, next); 156 157 kfree(table_en, M_DM); 158 } 159 160 lockmgr(&head->table_mtx, LK_RELEASE); 161 162 return 0; 163 } 164 /* 165 * Return length of active table in device. 166 */ 167 uint64_t 168 dm_table_size(dm_table_head_t * head) 169 { 170 dm_table_t *tbl; 171 dm_table_entry_t *table_en; 172 uint64_t length; 173 uint8_t id; 174 175 length = 0; 176 177 id = dm_table_busy(head, DM_TABLE_ACTIVE); 178 179 /* Select active table */ 180 tbl = &head->tables[id]; 181 182 /* 183 * Find out what tables I want to select. 184 * if length => rawblkno then we should used that table. 185 */ 186 SLIST_FOREACH(table_en, tbl, next) { 187 length += table_en->length; 188 } 189 190 dm_table_unbusy(head); 191 192 return length; 193 } 194 /* 195 * Return > 0 if table is at least one table entry (returns number of entries) 196 * and return 0 if there is not. Target count returned from this function 197 * doesn't need to be true when userspace user receive it (after return 198 * there can be dm_dev_resume_ioctl), therfore this isonly informative. 199 */ 200 int 201 dm_table_get_target_count(dm_table_head_t * head, uint8_t table_id) 202 { 203 dm_table_entry_t *table_en; 204 dm_table_t *tbl; 205 uint32_t target_count; 206 uint8_t id; 207 208 target_count = 0; 209 210 id = dm_table_busy(head, table_id); 211 212 tbl = &head->tables[id]; 213 214 SLIST_FOREACH(table_en, tbl, next) 215 target_count++; 216 217 dm_table_unbusy(head); 218 219 return target_count; 220 } 221 222 223 /* 224 * Initialize table_head structures, I'm trying to keep this structure as 225 * opaque as possible. 226 */ 227 void 228 dm_table_head_init(dm_table_head_t * head) 229 { 230 head->cur_active_table = 0; 231 head->io_cnt = 0; 232 233 /* Initialize tables. */ 234 SLIST_INIT(&head->tables[0]); 235 SLIST_INIT(&head->tables[1]); 236 237 lockinit(&head->table_mtx, "dmtbl", 0, LK_CANRECURSE); 238 } 239 /* 240 * Destroy all variables in table_head 241 */ 242 void 243 dm_table_head_destroy(dm_table_head_t * head) 244 { 245 KKASSERT(lockcount(&head->table_mtx) == 0); 246 247 /* tables doens't exists when I call this routine, therefore it 248 * doesn't make sense to have io_cnt != 0 */ 249 KKASSERT(head->io_cnt == 0); 250 251 lockuninit(&head->table_mtx); 252 } 253