sys/dev/disk/dm/dm_table.c

   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/malloc.h>
  34 #include <cpu/atomic.h>
  35 #include <dev/disk/dm/dm.h>
  36
  37 /*
  38  * There are two types of users of this interface:
  39  *
  40  * a) Readers such as
  41  *    dmstrategy, dmgetdisklabel, dmsize, dm_dev_status_ioctl,
  42  *    dm_table_deps_ioctl, dm_table_status_ioctl, dm_table_reload_ioctl
  43  *
  44  * b) Writers such as
  45  *    dm_dev_remove_ioctl, dm_dev_resume_ioctl, dm_table_clear_ioctl
  46  *
  47  * Writers can work with table_head only when there are no readers. We
  48  * simply use shared/exclusive locking to ensure this.
  49  */
  50
  51 /*
  52  * Function to increment table user reference counter. Return id
  53  * of table_id table.
  54  * DM_TABLE_ACTIVE will return active table id.
  55  * DM_TABLE_INACTIVE will return inactive table id.
  56  */
  57 static int
  58 dm_table_busy(dm_table_head_t *head, uint8_t table_id)
  59 {
  60         uint8_t id;
  61
  62         id = 0;
  63
  64         lockmgr(&head->table_mtx, LK_SHARED);
  65
  66         if (table_id == DM_TABLE_ACTIVE)
  67                 id = head->cur_active_table;
  68         else
  69                 id = 1 - head->cur_active_table;
  70
  71         atomic_add_int(&head->io_cnt, 1);
  72
  73         return id;
  74 }
  75
  76 /*
  77  * Function release table lock and eventually wakeup all waiters.
  78  */
  79 static void
  80 dm_table_unbusy(dm_table_head_t *head)
  81 {
  82         KKASSERT(head->io_cnt != 0);
  83
  84         atomic_subtract_int(&head->io_cnt, 1);
  85
  86         lockmgr(&head->table_mtx, LK_RELEASE);
  87 }
  88
  89 /*
  90  * Return current active table to caller, increment io_cnt reference counter.
  91  */
  92 dm_table_t *
  93 dm_table_get_entry(dm_table_head_t *head, uint8_t table_id)
  94 {
  95         uint8_t id;
  96
  97         id = dm_table_busy(head, table_id);
  98
  99         return &head->tables[id];
 100 }
 101
 102 /*
 103  * Decrement io reference counter and release shared lock.
 104  */
 105 void
 106 dm_table_release(dm_table_head_t *head, uint8_t table_id)
 107 {
 108         dm_table_unbusy(head);
 109 }
 110
 111 /*
 112  * Switch table from inactive to active mode. Have to wait until io_cnt is 0.
 113  */
 114 void
 115 dm_table_switch_tables(dm_table_head_t *head)
 116 {
 117         lockmgr(&head->table_mtx, LK_EXCLUSIVE);
 118
 119         head->cur_active_table = 1 - head->cur_active_table;
 120
 121         lockmgr(&head->table_mtx, LK_RELEASE);
 122 }
 123
 124 /*
 125  * Destroy all table data. This function can run when there are no
 126  * readers on table lists.
 127  */
 128 int
 129 dm_table_destroy(dm_table_head_t *head, uint8_t table_id)
 130 {
 131         dm_table_t *tbl;
 132         dm_table_entry_t *table_en;
 133         uint8_t id;
 134
 135         lockmgr(&head->table_mtx, LK_EXCLUSIVE);
 136
 137         dmdebug("table_id=%d io_cnt=%d\n", table_id, head->io_cnt);
 138
 139         if (table_id == DM_TABLE_ACTIVE)
 140                 id = head->cur_active_table;
 141         else
 142                 id = 1 - head->cur_active_table;
 143
 144         tbl = &head->tables[id];
 145
 146         while ((table_en = TAILQ_FIRST(tbl)) != NULL) {
 147                 TAILQ_REMOVE(tbl, table_en, next);
 148
 149                 if (table_en->target->destroy(table_en) == 0)
 150                         table_en->target_config = NULL;
 151
 152                 dm_table_free_deps(table_en);
 153
 154                 /* decrement the refcount for the target */
 155                 dm_target_unbusy(table_en->target);
 156
 157                 kfree(table_en, M_DM);
 158         }
 159         KKASSERT(TAILQ_EMPTY(tbl));
 160
 161         lockmgr(&head->table_mtx, LK_RELEASE);
 162
 163         return 0;
 164 }
 165
 166 /*
 167  * Return length of active or inactive table in device.
 168  */
 169 static uint64_t
 170 _dm_table_size(dm_table_head_t *head, int table)
 171 {
 172         dm_table_t *tbl;
 173         dm_table_entry_t *table_en;
 174         uint64_t length;
 175
 176         length = 0;
 177
 178         /* Select active table */
 179         tbl = dm_table_get_entry(head, table);
 180
 181         /*
 182          * Find out what tables I want to select.
 183          * if length => rawblkno then we should used that table.
 184          */
 185         TAILQ_FOREACH(table_en, tbl, next) {
 186                 length += table_en->length;
 187         }
 188
 189         dm_table_unbusy(head);
 190
 191         return length;
 192 }
 193
 194 uint64_t
 195 dm_table_size(dm_table_head_t *head)
 196 {
 197         return _dm_table_size(head, DM_TABLE_ACTIVE);
 198 }
 199
 200 uint64_t
 201 dm_inactive_table_size(dm_table_head_t *head)
 202 {
 203         return _dm_table_size(head, DM_TABLE_INACTIVE);
 204 }
 205
 206 /*
 207  * Return > 0 if table is at least one table entry (returns number of entries)
 208  * and return 0 if there is not. Target count returned from this function
 209  * doesn't need to be true when userspace user receive it (after return
 210  * there can be dm_dev_resume_ioctl), therefore this is only informative.
 211  */
 212 int
 213 dm_table_get_target_count(dm_table_head_t *head, uint8_t table_id)
 214 {
 215         dm_table_entry_t *table_en;
 216         dm_table_t *tbl;
 217         uint32_t target_count;
 218
 219         target_count = 0;
 220
 221         tbl = dm_table_get_entry(head, table_id);
 222
 223         TAILQ_FOREACH(table_en, tbl, next)
 224             target_count++;
 225
 226         dm_table_unbusy(head);
 227
 228         return target_count;
 229 }
 230
 231 /*
 232  * Initialize dm_table_head_t structures, I'm trying to keep this structure as
 233  * opaque as possible.
 234  */
 235 void
 236 dm_table_head_init(dm_table_head_t *head)
 237 {
 238         head->cur_active_table = 0;
 239         head->io_cnt = 0;
 240
 241         /* Initialize tables. */
 242         TAILQ_INIT(&head->tables[0]);
 243         TAILQ_INIT(&head->tables[1]);
 244
 245         lockinit(&head->table_mtx, "dmtbl", 0, LK_CANRECURSE);
 246 }
 247
 248 /*
 249  * Destroy all variables in table_head
 250  */
 251 void
 252 dm_table_head_destroy(dm_table_head_t *head)
 253 {
 254         KKASSERT(lockcount(&head->table_mtx) == 0);
 255
 256         /* tables don't exist when I call this routine, therefore it
 257          * doesn't make sense to have io_cnt != 0 */
 258         KKASSERT(head->io_cnt == 0);
 259
 260         lockuninit(&head->table_mtx);
 261 }
 262
 263 void
 264 dm_table_init_target(dm_table_entry_t *table_en, void *cfg)
 265 {
 266         table_en->target_config = cfg;
 267 }
 268
 269 int
 270 dm_table_add_deps(dm_table_entry_t *table_en, dm_pdev_t *pdev)
 271 {
 272         dm_table_head_t *head;
 273         dm_mapping_t *map;
 274
 275         KKASSERT(pdev);
 276
 277         head = &table_en->dev->table_head;
 278         lockmgr(&head->table_mtx, LK_SHARED);
 279
 280         TAILQ_FOREACH(map, &table_en->pdev_maps, next) {
 281                 if (map->data.pdev->udev == pdev->udev) {
 282                         lockmgr(&head->table_mtx, LK_RELEASE);
 283                         return -1;
 284                 }
 285         }
 286
 287         map = kmalloc(sizeof(*map), M_DM, M_WAITOK | M_ZERO);
 288         map->data.pdev = pdev;
 289         TAILQ_INSERT_TAIL(&table_en->pdev_maps, map, next);
 290
 291         lockmgr(&head->table_mtx, LK_RELEASE);
 292
 293         return 0;
 294 }
 295
 296 void
 297 dm_table_free_deps(dm_table_entry_t *table_en)
 298 {
 299         dm_table_head_t *head;
 300         dm_mapping_t *map;
 301
 302         head = &table_en->dev->table_head;
 303         lockmgr(&head->table_mtx, LK_SHARED);
 304
 305         while ((map = TAILQ_FIRST(&table_en->pdev_maps)) != NULL) {
 306                 TAILQ_REMOVE(&table_en->pdev_maps, map, next);
 307                 kfree(map, M_DM);
 308         }
 309         KKASSERT(TAILQ_EMPTY(&table_en->pdev_maps));
 310
 311         lockmgr(&head->table_mtx, LK_RELEASE);
 312 }