Pull netlink into release branch
[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         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         if (argc == 3) {
167                 dc->dev_write = NULL;
168                 goto out;
169         }
170
171         if (sscanf(argv[4], "%llu", &tmpll) != 1) {
172                 ti->error = "Invalid write device sector";
173                 goto bad;
174         }
175         dc->start_write = tmpll;
176
177         if (sscanf(argv[5], "%u", &dc->write_delay) != 1) {
178                 ti->error = "Invalid write delay";
179                 goto bad;
180         }
181
182         if (dm_get_device(ti, argv[3], dc->start_write, ti->len,
183                           dm_table_get_mode(ti->table), &dc->dev_write)) {
184                 ti->error = "Write device lookup failed";
185                 dm_put_device(ti, dc->dev_read);
186                 goto bad;
187         }
188
189 out:
190         dc->delayed_pool = mempool_create_slab_pool(128, delayed_cache);
191         if (!dc->delayed_pool) {
192                 DMERR("Couldn't create delayed bio pool.");
193                 goto bad;
194         }
195
196         setup_timer(&dc->delay_timer, handle_delayed_timer, (unsigned long)dc);
197
198         INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
199         INIT_LIST_HEAD(&dc->delayed_bios);
200         mutex_init(&dc->timer_lock);
201         atomic_set(&dc->may_delay, 1);
202
203         ti->private = dc;
204         return 0;
205
206 bad:
207         kfree(dc);
208         return -EINVAL;
209 }
210
211 static void delay_dtr(struct dm_target *ti)
212 {
213         struct delay_c *dc = ti->private;
214
215         flush_workqueue(kdelayd_wq);
216
217         dm_put_device(ti, dc->dev_read);
218
219         if (dc->dev_write)
220                 dm_put_device(ti, dc->dev_write);
221
222         mempool_destroy(dc->delayed_pool);
223         kfree(dc);
224 }
225
226 static int delay_bio(struct delay_c *dc, int delay, struct bio *bio)
227 {
228         struct dm_delay_info *delayed;
229         unsigned long expires = 0;
230
231         if (!delay || !atomic_read(&dc->may_delay))
232                 return 1;
233
234         delayed = mempool_alloc(dc->delayed_pool, GFP_NOIO);
235
236         delayed->context = dc;
237         delayed->bio = bio;
238         delayed->expires = expires = jiffies + (delay * HZ / 1000);
239
240         mutex_lock(&delayed_bios_lock);
241
242         if (bio_data_dir(bio) == WRITE)
243                 dc->writes++;
244         else
245                 dc->reads++;
246
247         list_add_tail(&delayed->list, &dc->delayed_bios);
248
249         mutex_unlock(&delayed_bios_lock);
250
251         queue_timeout(dc, expires);
252
253         return 0;
254 }
255
256 static void delay_presuspend(struct dm_target *ti)
257 {
258         struct delay_c *dc = ti->private;
259
260         atomic_set(&dc->may_delay, 0);
261         del_timer_sync(&dc->delay_timer);
262         flush_bios(flush_delayed_bios(dc, 1));
263 }
264
265 static void delay_resume(struct dm_target *ti)
266 {
267         struct delay_c *dc = ti->private;
268
269         atomic_set(&dc->may_delay, 1);
270 }
271
272 static int delay_map(struct dm_target *ti, struct bio *bio,
273                      union map_info *map_context)
274 {
275         struct delay_c *dc = ti->private;
276
277         if ((bio_data_dir(bio) == WRITE) && (dc->dev_write)) {
278                 bio->bi_bdev = dc->dev_write->bdev;
279                 bio->bi_sector = dc->start_write +
280                                  (bio->bi_sector - ti->begin);
281
282                 return delay_bio(dc, dc->write_delay, bio);
283         }
284
285         bio->bi_bdev = dc->dev_read->bdev;
286         bio->bi_sector = dc->start_read +
287                          (bio->bi_sector - ti->begin);
288
289         return delay_bio(dc, dc->read_delay, bio);
290 }
291
292 static int delay_status(struct dm_target *ti, status_type_t type,
293                         char *result, unsigned maxlen)
294 {
295         struct delay_c *dc = ti->private;
296         int sz = 0;
297
298         switch (type) {
299         case STATUSTYPE_INFO:
300                 DMEMIT("%u %u", dc->reads, dc->writes);
301                 break;
302
303         case STATUSTYPE_TABLE:
304                 DMEMIT("%s %llu %u", dc->dev_read->name,
305                        (unsigned long long) dc->start_read,
306                        dc->read_delay);
307                 if (dc->dev_write)
308                         DMEMIT("%s %llu %u", dc->dev_write->name,
309                                (unsigned long long) dc->start_write,
310                                dc->write_delay);
311                 break;
312         }
313
314         return 0;
315 }
316
317 static struct target_type delay_target = {
318         .name        = "delay",
319         .version     = {1, 0, 2},
320         .module      = THIS_MODULE,
321         .ctr         = delay_ctr,
322         .dtr         = delay_dtr,
323         .map         = delay_map,
324         .presuspend  = delay_presuspend,
325         .resume      = delay_resume,
326         .status      = delay_status,
327 };
328
329 static int __init dm_delay_init(void)
330 {
331         int r = -ENOMEM;
332
333         kdelayd_wq = create_workqueue("kdelayd");
334         if (!kdelayd_wq) {
335                 DMERR("Couldn't start kdelayd");
336                 goto bad_queue;
337         }
338
339         delayed_cache = KMEM_CACHE(dm_delay_info, 0);
340         if (!delayed_cache) {
341                 DMERR("Couldn't create delayed bio cache.");
342                 goto bad_memcache;
343         }
344
345         r = dm_register_target(&delay_target);
346         if (r < 0) {
347                 DMERR("register failed %d", r);
348                 goto bad_register;
349         }
350
351         return 0;
352
353 bad_register:
354         kmem_cache_destroy(delayed_cache);
355 bad_memcache:
356         destroy_workqueue(kdelayd_wq);
357 bad_queue:
358         return r;
359 }
360
361 static void __exit dm_delay_exit(void)
362 {
363         int r = dm_unregister_target(&delay_target);
364
365         if (r < 0)
366                 DMERR("unregister failed %d", r);
367
368         kmem_cache_destroy(delayed_cache);
369         destroy_workqueue(kdelayd_wq);
370 }
371
372 /* Module hooks */
373 module_init(dm_delay_init);
374 module_exit(dm_delay_exit);
375
376 MODULE_DESCRIPTION(DM_NAME " delay target");
377 MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
378 MODULE_LICENSE("GPL");