1 /* $NetBSD: dm_table.c,v 1.5 2010/01/04 00:19:08 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 #include <sys/types.h> 33 #include <sys/param.h> 34 35 #include <sys/malloc.h> 36 37 #include "dm.h" 38 39 MALLOC_DECLARE(M_DM); 40 41 /* 42 * There are two types of users of this interface: 43 * 44 * a) Readers such as 45 * dmstrategy, dmgetdisklabel, dmsize, dm_dev_status_ioctl, 46 * dm_table_deps_ioctl, dm_table_status_ioctl, dm_table_reload_ioctl 47 * 48 * b) Writers such as 49 * dm_dev_remove_ioctl, dm_dev_resume_ioctl, dm_table_clear_ioctl 50 * 51 * Writers can work with table_head only when there are no readers. I 52 * use reference counting on io_cnt. 53 * 54 */ 55 56 static int dm_table_busy(dm_table_head_t *, uint8_t); 57 static void dm_table_unbusy(dm_table_head_t *); 58 59 /* 60 * Function to increment table user reference counter. Return id 61 * of table_id table. 62 * DM_TABLE_ACTIVE will return active table id. 63 * DM_TABLE_INACTIVE will return inactive table id. 64 */ 65 static int 66 dm_table_busy(dm_table_head_t * head, uint8_t table_id) 67 { 68 uint8_t id; 69 70 id = 0; 71 72 lockmgr(&head->table_mtx, LK_EXCLUSIVE); 73 74 if (table_id == DM_TABLE_ACTIVE) 75 id = head->cur_active_table; 76 else 77 id = 1 - head->cur_active_table; 78 79 head->io_cnt++; 80 81 lockmgr(&head->table_mtx, LK_RELEASE); 82 return id; 83 } 84 /* 85 * Function release table lock and eventually wakeup all waiters. 86 */ 87 static void 88 dm_table_unbusy(dm_table_head_t * head) 89 { 90 KKASSERT(head->io_cnt != 0); 91 92 lockmgr(&head->table_mtx, LK_EXCLUSIVE); 93 94 if (--head->io_cnt == 0) 95 cv_broadcast(&head->table_cv); 96 97 lockmgr(&head->table_mtx, LK_RELEASE); 98 } 99 /* 100 * Return current active table to caller, increment io_cnt reference counter. 101 */ 102 dm_table_t * 103 dm_table_get_entry(dm_table_head_t * head, uint8_t table_id) 104 { 105 uint8_t id; 106 107 id = dm_table_busy(head, table_id); 108 109 return &head->tables[id]; 110 } 111 /* 112 * Decrement io reference counter and wake up all callers, with table_head cv. 113 */ 114 void 115 dm_table_release(dm_table_head_t * head, uint8_t table_id) 116 { 117 dm_table_unbusy(head); 118 } 119 /* 120 * Switch table from inactive to active mode. Have to wait until io_cnt is 0. 121 */ 122 void 123 dm_table_switch_tables(dm_table_head_t * head) 124 { 125 lockmgr(&head->table_mtx, LK_EXCLUSIVE); 126 127 while (head->io_cnt != 0) 128 cv_wait(&head->table_cv, &head->table_mtx); 129 130 head->cur_active_table = 1 - head->cur_active_table; 131 132 lockmgr(&head->table_mtx, LK_RELEASE); 133 } 134 /* 135 * Destroy all table data. This function can run when there are no 136 * readers on table lists. 137 * 138 * XXX Is it ok to call kmem_free and potentialy VOP_CLOSE with held mutex ?xs 139 */ 140 int 141 dm_table_destroy(dm_table_head_t * head, uint8_t table_id) 142 { 143 dm_table_t *tbl; 144 dm_table_entry_t *table_en; 145 uint8_t id; 146 147 lockmgr(&head->table_mtx, LK_EXCLUSIVE); 148 149 aprint_debug("dm_Table_destroy called with %d--%d\n", table_id, head->io_cnt); 150 151 while (head->io_cnt != 0) 152 cv_wait(&head->table_cv, &head->table_mtx); 153 154 if (table_id == DM_TABLE_ACTIVE) 155 id = head->cur_active_table; 156 else 157 id = 1 - head->cur_active_table; 158 159 tbl = &head->tables[id]; 160 161 while (!SLIST_EMPTY(tbl)) { /* List Deletion. */ 162 table_en = SLIST_FIRST(tbl); 163 /* 164 * Remove target specific config data. After successfull 165 * call table_en->target_config must be set to NULL. 166 */ 167 table_en->target->destroy(table_en); 168 169 SLIST_REMOVE_HEAD(tbl, next); 170 171 kfree(table_en, M_DM); 172 } 173 174 lockmgr(&head->table_mtx, LK_RELEASE); 175 176 return 0; 177 } 178 /* 179 * Return length of active table in device. 180 */ 181 uint64_t 182 dm_table_size(dm_table_head_t * head) 183 { 184 dm_table_t *tbl; 185 dm_table_entry_t *table_en; 186 uint64_t length; 187 uint8_t id; 188 189 length = 0; 190 191 id = dm_table_busy(head, DM_TABLE_ACTIVE); 192 193 /* Select active table */ 194 tbl = &head->tables[id]; 195 196 /* 197 * Find out what tables I want to select. 198 * if length => rawblkno then we should used that table. 199 */ 200 SLIST_FOREACH(table_en, tbl, next) { 201 length += table_en->length; 202 } 203 204 dm_table_unbusy(head); 205 206 return length; 207 } 208 /* 209 * Return > 0 if table is at least one table entry (returns number of entries) 210 * and return 0 if there is not. Target count returned from this function 211 * doesn't need to be true when userspace user receive it (after return 212 * there can be dm_dev_resume_ioctl), therfore this isonly informative. 213 */ 214 int 215 dm_table_get_target_count(dm_table_head_t * head, uint8_t table_id) 216 { 217 dm_table_entry_t *table_en; 218 dm_table_t *tbl; 219 uint32_t target_count; 220 uint8_t id; 221 222 target_count = 0; 223 224 id = dm_table_busy(head, table_id); 225 226 tbl = &head->tables[id]; 227 228 SLIST_FOREACH(table_en, tbl, next) 229 target_count++; 230 231 dm_table_unbusy(head); 232 233 return target_count; 234 } 235 236 237 /* 238 * Initialize table_head structures, I'm trying to keep this structure as 239 * opaque as possible. 240 */ 241 void 242 dm_table_head_init(dm_table_head_t * head) 243 { 244 head->cur_active_table = 0; 245 head->io_cnt = 0; 246 247 /* Initialize tables. */ 248 SLIST_INIT(&head->tables[0]); 249 SLIST_INIT(&head->tables[1]); 250 251 lockinit(&head->table_mtx, "dmtbl", 0, LK_CANRECURSE); 252 cv_init(&head->table_cv, "dm_io"); 253 } 254 /* 255 * Destroy all variables in table_head 256 */ 257 void 258 dm_table_head_destroy(dm_table_head_t * head) 259 { 260 KKASSERT(lockcount(&head->table_mtx) == 0); 261 #if 0 262 KKASSERT(!cv_has_waiters(&head->table_cv)); 263 #endif 264 /* tables doens't exists when I call this routine, therefore it 265 * doesn't make sense to have io_cnt != 0 */ 266 KKASSERT(head->io_cnt == 0); 267 268 cv_destroy(&head->table_cv); 269 lockuninit(&head->table_mtx); 270 } 271