1/* $NetBSD: dm_table.c,v 1.7 2011/08/27 17:10:05 ahoka 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/kmem.h>
36
37#include "dm.h"
38
39/*
40 * There are two types of users of this interface:
41 *
42 * a) Readers such as
43 * dmstrategy, dmgetdisklabel, dmsize, dm_dev_status_ioctl,
44 * dm_table_deps_ioctl, dm_table_status_ioctl, dm_table_reload_ioctl
45 *
46 * b) Writers such as
47 * dm_dev_remove_ioctl, dm_dev_resume_ioctl, dm_table_clear_ioctl
48 *
49 * Writers can work with table_head only when there are no readers. I
50 * use reference counting on io_cnt.
51 *
52 */
53
54static int dm_table_busy(dm_table_head_t *, uint8_t);
55static 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 */
63static int
64dm_table_busy(dm_table_head_t * head, uint8_t table_id)
65{
66 uint8_t id;
67
68 id = 0;
69
70 mutex_enter(&head->table_mtx);
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 head->io_cnt++;
78
79 mutex_exit(&head->table_mtx);
80 return id;
81}
82/*
83 * Function release table lock and eventually wakeup all waiters.
84 */
85static void
86dm_table_unbusy(dm_table_head_t * head)
87{
88 KASSERT(head->io_cnt != 0);
89
90 mutex_enter(&head->table_mtx);
91
92 if (--head->io_cnt == 0)
93 cv_broadcast(&head->table_cv);
94
95 mutex_exit(&head->table_mtx);
96}
97/*
98 * Return current active table to caller, increment io_cnt reference counter.
99 */
100dm_table_t *
101dm_table_get_entry(dm_table_head_t * head, uint8_t table_id)
102{
103 uint8_t id;
104
105 id = dm_table_busy(head, table_id);
106
107 return &head->tables[id];
108}
109/*
110 * Decrement io reference counter and wake up all callers, with table_head cv.
111 */
112void
113dm_table_release(dm_table_head_t * head, uint8_t table_id)
114{
115 dm_table_unbusy(head);
116}
117/*
118 * Switch table from inactive to active mode. Have to wait until io_cnt is 0.
119 */
120void
121dm_table_switch_tables(dm_table_head_t * head)
122{
123 mutex_enter(&head->table_mtx);
124
125 while (head->io_cnt != 0)
126 cv_wait(&head->table_cv, &head->table_mtx);
127
128 head->cur_active_table = 1 - head->cur_active_table;
129
130 mutex_exit(&head->table_mtx);
131}
132/*
133 * Destroy all table data. This function can run when there are no
134 * readers on table lists.
135 *
136 * XXX Is it ok to call kmem_free and potentialy VOP_CLOSE with held mutex ?xs
137 */
138int
139dm_table_destroy(dm_table_head_t * head, uint8_t table_id)
140{
141 dm_table_t *tbl;
142 dm_table_entry_t *table_en;
143 uint8_t id;
144
145 mutex_enter(&head->table_mtx);
146
147 aprint_debug("dm_Table_destroy called with %d--%d\n", table_id, head->io_cnt);
148
149 while (head->io_cnt != 0)
150 cv_wait(&head->table_cv, &head->table_mtx);
151
152 if (table_id == DM_TABLE_ACTIVE)
153 id = head->cur_active_table;
154 else
155 id = 1 - head->cur_active_table;
156
157 tbl = &head->tables[id];
158
159 while (!SLIST_EMPTY(tbl)) { /* List Deletion. */
160 table_en = SLIST_FIRST(tbl);
161 /*
162 * Remove target specific config data. After successfull
163 * call table_en->target_config must be set to NULL.
164 */
165 table_en->target->destroy(table_en);
166
167 SLIST_REMOVE_HEAD(tbl, next);
168
169 kmem_free(table_en, sizeof(*table_en));
170 }
171
172 mutex_exit(&head->table_mtx);
173
174 return 0;
175}
176/*
177 * Return length of active table in device.
178 */
179static inline uint64_t
180dm_table_size_impl(dm_table_head_t * head, int table)
181{
182 dm_table_t *tbl;
183 dm_table_entry_t *table_en;
184 uint64_t length;
185 uint8_t id;
186
187 length = 0;
188
189 id = dm_table_busy(head, table);
190
191 /* Select active table */
192 tbl = &head->tables[id];
193
194 /*
195 * Find out what tables I want to select.
196 * if length => rawblkno then we should used that table.
197 */
198 SLIST_FOREACH(table_en, tbl, next)
199 length += table_en->length;
200
201 dm_table_unbusy(head);
202
203 return length;
204}
205
206/*
207 * Return length of active table in device.
208 */
209uint64_t
210dm_table_size(dm_table_head_t * head)
211{
212 return dm_table_size_impl(head, DM_TABLE_ACTIVE);
213}
214
215/*
216 * Return length of active table in device.
217 */
218uint64_t
219dm_inactive_table_size(dm_table_head_t * head)
220{
221 return dm_table_size_impl(head, DM_TABLE_INACTIVE);
222}
223
224/*
225 * Return combined disk geometry
226 */
227void
228dm_table_disksize(dm_table_head_t * head, uint64_t *numsecp, unsigned *secsizep)
229{
230 dm_table_t *tbl;
231 dm_table_entry_t *table_en;
232 uint64_t length;
233 unsigned secsize, tsecsize;
234 uint8_t id;
235
236 length = 0;
237
238 id = dm_table_busy(head, DM_TABLE_ACTIVE);
239
240 /* Select active table */
241 tbl = &head->tables[id];
242
243 /*
244 * Find out what tables I want to select.
245 * if length => rawblkno then we should used that table.
246 */
247 secsize = 0;
248 SLIST_FOREACH(table_en, tbl, next) {
249 length += table_en->length;
250 (void)table_en->target->secsize(table_en, &tsecsize);
251 if (secsize < tsecsize)
252 secsize = tsecsize;
253 }
254 *numsecp = secsize > 0 ? dbtob(length) / secsize : 0;
255 *secsizep = secsize;
256
257 dm_table_unbusy(head);
258}
259/*
260 * Return > 0 if table is at least one table entry (returns number of entries)
261 * and return 0 if there is not. Target count returned from this function
262 * doesn't need to be true when userspace user receive it (after return
263 * there can be dm_dev_resume_ioctl), therfore this isonly informative.
264 */
265int
266dm_table_get_target_count(dm_table_head_t * head, uint8_t table_id)
267{
268 dm_table_entry_t *table_en;
269 dm_table_t *tbl;
270 uint32_t target_count;
271 uint8_t id;
272
273 target_count = 0;
274
275 id = dm_table_busy(head, table_id);
276
277 tbl = &head->tables[id];
278
279 SLIST_FOREACH(table_en, tbl, next)
280 target_count++;
281
282 dm_table_unbusy(head);
283
284 return target_count;
285}
286
287
288/*
289 * Initialize table_head structures, I'm trying to keep this structure as
290 * opaque as possible.
291 */
292void
293dm_table_head_init(dm_table_head_t * head)
294{
295 head->cur_active_table = 0;
296 head->io_cnt = 0;
297
298 /* Initialize tables. */
299 SLIST_INIT(&head->tables[0]);
300 SLIST_INIT(&head->tables[1]);
301
302 mutex_init(&head->table_mtx, MUTEX_DEFAULT, IPL_NONE);
303 cv_init(&head->table_cv, "dm_io");
304}
305/*
306 * Destroy all variables in table_head
307 */
308void
309dm_table_head_destroy(dm_table_head_t * head)
310{
311 KASSERT(!mutex_owned(&head->table_mtx));
312 KASSERT(!cv_has_waiters(&head->table_cv));
313 /* tables doens't exists when I call this routine, therefore it
314 * doesn't make sense to have io_cnt != 0 */
315 KASSERT(head->io_cnt == 0);
316
317 cv_destroy(&head->table_cv);
318 mutex_destroy(&head->table_mtx);
319}
320