Merge commit 'v2.6.27-rc8' into genirq
[linux-2.6] / drivers / md / dm-delay.c
1 /*
2  * Copyright (C) 2005-2007 Red Hat GmbH
3  *
4  * A target that delays reads and/or writes and can send
5  * them to different devices.
6  *
7  * This file is released under the GPL.
8  */
9
10 #include <linux/module.h>
11 #include <linux/init.h>
12 #include <linux/blkdev.h>
13 #include <linux/bio.h>
14 #include <linux/slab.h>
15
16 #include "dm.h"
17 #include "dm-bio-list.h"
18
19 #define DM_MSG_PREFIX "delay"
20
21 struct delay_c {
22         struct timer_list delay_timer;
23         struct mutex timer_lock;
24         struct work_struct flush_expired_bios;
25         struct list_head delayed_bios;
26         atomic_t may_delay;
27         mempool_t *delayed_pool;
28
29         struct dm_dev *dev_read;
30         sector_t start_read;
31         unsigned read_delay;
32         unsigned reads;
33
34         struct dm_dev *dev_write;
35         sector_t start_write;
36         unsigned write_delay;
37         unsigned writes;
38 };
39
40 struct dm_delay_info {
41         struct delay_c *context;
42         struct list_head list;
43         struct bio *bio;
44         unsigned long expires;
45 };
46
47 static DEFINE_MUTEX(delayed_bios_lock);
48
49 static struct workqueue_struct *kdelayd_wq;
50 static struct kmem_cache *delayed_cache;
51
52 static void handle_delayed_timer(unsigned long data)
53 {
54         struct delay_c *dc = (struct delay_c *)data;
55
56         queue_work(kdelayd_wq, &dc->flush_expired_bios);
57 }
58
59 static void queue_timeout(struct delay_c *dc, unsigned long expires)
60 {
61         mutex_lock(&dc->timer_lock);
62
63         if (!timer_pending(&dc->delay_timer) || expires < dc->delay_timer.expires)
64                 mod_timer(&dc->delay_timer, expires);
65
66         mutex_unlock(&dc->timer_lock);
67 }
68
69 static void flush_bios(struct bio *bio)
70 {
71         struct bio *n;
72
73         while (bio) {
74                 n = bio->bi_next;
75                 bio->bi_next = NULL;
76                 generic_make_request(bio);
77                 bio = n;
78         }
79 }
80
81 static struct bio *flush_delayed_bios(struct delay_c *dc, int flush_all)
82 {
83         struct dm_delay_info *delayed, *next;
84         unsigned long next_expires = 0;
85         int start_timer = 0;
86         struct bio_list flush_bios = { };
87
88         mutex_lock(&delayed_bios_lock);
89         list_for_each_entry_safe(delayed, next, &dc->delayed_bios, list) {
90                 if (flush_all || time_after_eq(jiffies, delayed->expires)) {
91                         list_del(&delayed->list);
92                         bio_list_add(&flush_bios, delayed->bio);
93                         if ((bio_data_dir(delayed->bio) == WRITE))
94                                 delayed->context->writes--;
95                         else
96                                 delayed->context->reads--;
97                         mempool_free(delayed, dc->delayed_pool);
98                         continue;
99                 }
100
101                 if (!start_timer) {
102                         start_timer = 1;
103                         next_expires = delayed->expires;
104                 } else
105                         next_expires = min(next_expires, delayed->expires);
106         }
107
108         mutex_unlock(&delayed_bios_lock);
109
110         if (start_timer)
111                 queue_timeout(dc, next_expires);
112
113         return bio_list_get(&flush_bios);
114 }
115
116 static void flush_expired_bios(struct work_struct *work)
117 {
118         struct delay_c *dc;
119
120         dc = container_of(work, struct delay_c, flush_expired_bios);
121         flush_bios(flush_delayed_bios(dc, 0));
122 }
123
124 /*
125  * Mapping parameters:
126  *    <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
127  *
128  * With separate write parameters, the first set is only used for reads.
129  * Delays are specified in milliseconds.
130  */
131 static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv)
132 {
133         struct delay_c *dc;
134         unsigned long long tmpll;
135
136         if (argc != 3 && argc != 6) {
137                 ti->error = "requires exactly 3 or 6 arguments";
138                 return -EINVAL;
139         }
140
141         dc = kmalloc(sizeof(*dc), GFP_KERNEL);
142         if (!dc) {
143                 ti->error = "Cannot allocate context";
144                 return -ENOMEM;
145         }
146
147         dc->reads = dc->writes = 0;
148
149         if (sscanf(argv[1], "%llu", &tmpll) != 1) {
150                 ti->error = "Invalid device sector";
151                 goto bad;
152         }
153         dc->start_read = tmpll;
154
155         if (sscanf(argv[2], "%u", &dc->read_delay) != 1) {
156                 ti->error = "Invalid delay";
157                 goto bad;
158         }
159
160         if (dm_get_device(ti, argv[0], dc->start_read, ti->len,
161                           dm_table_get_mode(ti->table), &dc->dev_read)) {
162                 ti->error = "Device lookup failed";
163                 goto bad;
164         }
165
166         dc->dev_write = NULL;
167         if (argc == 3)
168                 goto out;
169
170         if (sscanf(argv[4], "%llu", &tmpll) != 1) {
171                 ti->error = "Invalid write device sector";
172                 goto bad_dev_read;
173         }
174         dc->start_write = tmpll;
175
176         if (sscanf(argv[5], "%u", &dc->write_delay) != 1) {
177                 ti->error = "Invalid write delay";
178                 goto bad_dev_read;
179         }
180
181         if (dm_get_device(ti, argv[3], dc->start_write, ti->len,
182                           dm_table_get_mode(ti->table), &dc->dev_write)) {
183                 ti->error = "Write device lookup failed";
184                 goto bad_dev_read;
185         }
186
187 out:
188         dc->delayed_pool = mempool_create_slab_pool(128, delayed_cache);
189         if (!dc->delayed_pool) {
190                 DMERR("Couldn't create delayed bio pool.");
191                 goto bad_dev_write;
192         }
193
194         setup_timer(&dc->delay_timer, handle_delayed_timer, (unsigned long)dc);
195
196         INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
197         INIT_LIST_HEAD(&dc->delayed_bios);
198         mutex_init(&dc->timer_lock);
199         atomic_set(&dc->may_delay, 1);
200
201         ti->private = dc;
202         return 0;
203
204 bad_dev_write:
205         if (dc->dev_write)
206                 dm_put_device(ti, dc->dev_write);
207 bad_dev_read:
208         dm_put_device(ti, dc->dev_read);
209 bad:
210         kfree(dc);
211         return -EINVAL;
212 }
213
214 static void delay_dtr(struct dm_target *ti)
215 {
216         struct delay_c *dc = ti->private;
217
218         flush_workqueue(kdelayd_wq);
219
220         dm_put_device(ti, dc->dev_read);
221
222         if (dc->dev_write)
223                 dm_put_device(ti, dc->dev_write);
224
225         mempool_destroy(dc->delayed_pool);
226         kfree(dc);
227 }
228
229 static int delay_bio(struct delay_c *dc, int delay, struct bio *bio)
230 {
231         struct dm_delay_info *delayed;
232         unsigned long expires = 0;
233
234         if (!delay || !atomic_read(&dc->may_delay))
235                 return 1;
236
237         delayed = mempool_alloc(dc->delayed_pool, GFP_NOIO);
238
239         delayed->context = dc;
240         delayed->bio = bio;
241         delayed->expires = expires = jiffies + (delay * HZ / 1000);
242
243         mutex_lock(&delayed_bios_lock);
244
245         if (bio_data_dir(bio) == WRITE)
246                 dc->writes++;
247         else
248                 dc->reads++;
249
250         list_add_tail(&delayed->list, &dc->delayed_bios);
251
252         mutex_unlock(&delayed_bios_lock);
253
254         queue_timeout(dc, expires);
255
256         return 0;
257 }
258
259 static void delay_presuspend(struct dm_target *ti)
260 {
261         struct delay_c *dc = ti->private;
262
263         atomic_set(&dc->may_delay, 0);
264         del_timer_sync(&dc->delay_timer);
265         flush_bios(flush_delayed_bios(dc, 1));
266 }
267
268 static void delay_resume(struct dm_target *ti)
269 {
270         struct delay_c *dc = ti->private;
271
272         atomic_set(&dc->may_delay, 1);
273 }
274
275 static int delay_map(struct dm_target *ti, struct bio *bio,
276                      union map_info *map_context)
277 {
278         struct delay_c *dc = ti->private;
279
280         if ((bio_data_dir(bio) == WRITE) && (dc->dev_write)) {
281                 bio->bi_bdev = dc->dev_write->bdev;
282                 bio->bi_sector = dc->start_write +
283                                  (bio->bi_sector - ti->begin);
284
285                 return delay_bio(dc, dc->write_delay, bio);
286         }
287
288         bio->bi_bdev = dc->dev_read->bdev;
289         bio->bi_sector = dc->start_read +
290                          (bio->bi_sector - ti->begin);
291
292         return delay_bio(dc, dc->read_delay, bio);
293 }
294
295 static int delay_status(struct dm_target *ti, status_type_t type,
296                         char *result, unsigned maxlen)
297 {
298         struct delay_c *dc = ti->private;
299         int sz = 0;
300
301         switch (type) {
302         case STATUSTYPE_INFO:
303                 DMEMIT("%u %u", dc->reads, dc->writes);
304                 break;
305
306         case STATUSTYPE_TABLE:
307                 DMEMIT("%s %llu %u", dc->dev_read->name,
308                        (unsigned long long) dc->start_read,
309                        dc->read_delay);
310                 if (dc->dev_write)
311                         DMEMIT(" %s %llu %u", dc->dev_write->name,
312                                (unsigned long long) dc->start_write,
313                                dc->write_delay);
314                 break;
315         }
316
317         return 0;
318 }
319
320 static struct target_type delay_target = {
321         .name        = "delay",
322         .version     = {1, 0, 2},
323         .module      = THIS_MODULE,
324         .ctr         = delay_ctr,
325         .dtr         = delay_dtr,
326         .map         = delay_map,
327         .presuspend  = delay_presuspend,
328         .resume      = delay_resume,
329         .status      = delay_status,
330 };
331
332 static int __init dm_delay_init(void)
333 {
334         int r = -ENOMEM;
335
336         kdelayd_wq = create_workqueue("kdelayd");
337         if (!kdelayd_wq) {
338                 DMERR("Couldn't start kdelayd");
339                 goto bad_queue;
340         }
341
342         delayed_cache = KMEM_CACHE(dm_delay_info, 0);
343         if (!delayed_cache) {
344                 DMERR("Couldn't create delayed bio cache.");
345                 goto bad_memcache;
346         }
347
348         r = dm_register_target(&delay_target);
349         if (r < 0) {
350                 DMERR("register failed %d", r);
351                 goto bad_register;
352         }
353
354         return 0;
355
356 bad_register:
357         kmem_cache_destroy(delayed_cache);
358 bad_memcache:
359         destroy_workqueue(kdelayd_wq);
360 bad_queue:
361         return r;
362 }
363
364 static void __exit dm_delay_exit(void)
365 {
366         int r = dm_unregister_target(&delay_target);
367
368         if (r < 0)
369                 DMERR("unregister failed %d", r);
370
371         kmem_cache_destroy(delayed_cache);
372         destroy_workqueue(kdelayd_wq);
373 }
374
375 /* Module hooks */
376 module_init(dm_delay_init);
377 module_exit(dm_delay_exit);
378
379 MODULE_DESCRIPTION(DM_NAME " delay target");
380 MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
381 MODULE_LICENSE("GPL");