block: add sysfs knob for turning off disk entropy contributions
[linux-2.6.git] / block / blk-sysfs.c
1 /*
2  * Functions related to sysfs handling
3  */
4 #include <linux/kernel.h>
5 #include <linux/slab.h>
6 #include <linux/module.h>
7 #include <linux/bio.h>
8 #include <linux/blkdev.h>
9 #include <linux/blktrace_api.h>
10
11 #include "blk.h"
12
13 struct queue_sysfs_entry {
14         struct attribute attr;
15         ssize_t (*show)(struct request_queue *, char *);
16         ssize_t (*store)(struct request_queue *, const char *, size_t);
17 };
18
19 static ssize_t
20 queue_var_show(unsigned long var, char *page)
21 {
22         return sprintf(page, "%lu\n", var);
23 }
24
25 static ssize_t
26 queue_var_store(unsigned long *var, const char *page, size_t count)
27 {
28         char *p = (char *) page;
29
30         *var = simple_strtoul(p, &p, 10);
31         return count;
32 }
33
34 static ssize_t queue_requests_show(struct request_queue *q, char *page)
35 {
36         return queue_var_show(q->nr_requests, (page));
37 }
38
39 static ssize_t
40 queue_requests_store(struct request_queue *q, const char *page, size_t count)
41 {
42         struct request_list *rl = &q->rq;
43         unsigned long nr;
44         int ret;
45
46         if (!q->request_fn)
47                 return -EINVAL;
48
49         ret = queue_var_store(&nr, page, count);
50         if (nr < BLKDEV_MIN_RQ)
51                 nr = BLKDEV_MIN_RQ;
52
53         spin_lock_irq(q->queue_lock);
54         q->nr_requests = nr;
55         blk_queue_congestion_threshold(q);
56
57         if (rl->count[BLK_RW_SYNC] >= queue_congestion_on_threshold(q))
58                 blk_set_queue_congested(q, BLK_RW_SYNC);
59         else if (rl->count[BLK_RW_SYNC] < queue_congestion_off_threshold(q))
60                 blk_clear_queue_congested(q, BLK_RW_SYNC);
61
62         if (rl->count[BLK_RW_ASYNC] >= queue_congestion_on_threshold(q))
63                 blk_set_queue_congested(q, BLK_RW_ASYNC);
64         else if (rl->count[BLK_RW_ASYNC] < queue_congestion_off_threshold(q))
65                 blk_clear_queue_congested(q, BLK_RW_ASYNC);
66
67         if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
68                 blk_set_queue_full(q, BLK_RW_SYNC);
69         } else if (rl->count[BLK_RW_SYNC]+1 <= q->nr_requests) {
70                 blk_clear_queue_full(q, BLK_RW_SYNC);
71                 wake_up(&rl->wait[BLK_RW_SYNC]);
72         }
73
74         if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
75                 blk_set_queue_full(q, BLK_RW_ASYNC);
76         } else if (rl->count[BLK_RW_ASYNC]+1 <= q->nr_requests) {
77                 blk_clear_queue_full(q, BLK_RW_ASYNC);
78                 wake_up(&rl->wait[BLK_RW_ASYNC]);
79         }
80         spin_unlock_irq(q->queue_lock);
81         return ret;
82 }
83
84 static ssize_t queue_ra_show(struct request_queue *q, char *page)
85 {
86         unsigned long ra_kb = q->backing_dev_info.ra_pages <<
87                                         (PAGE_CACHE_SHIFT - 10);
88
89         return queue_var_show(ra_kb, (page));
90 }
91
92 static ssize_t
93 queue_ra_store(struct request_queue *q, const char *page, size_t count)
94 {
95         unsigned long ra_kb;
96         ssize_t ret = queue_var_store(&ra_kb, page, count);
97
98         q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);
99
100         return ret;
101 }
102
103 static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
104 {
105         int max_sectors_kb = queue_max_sectors(q) >> 1;
106
107         return queue_var_show(max_sectors_kb, (page));
108 }
109
110 static ssize_t queue_max_segments_show(struct request_queue *q, char *page)
111 {
112         return queue_var_show(queue_max_segments(q), (page));
113 }
114
115 static ssize_t queue_max_segment_size_show(struct request_queue *q, char *page)
116 {
117         if (test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags))
118                 return queue_var_show(queue_max_segment_size(q), (page));
119
120         return queue_var_show(PAGE_CACHE_SIZE, (page));
121 }
122
123 static ssize_t queue_logical_block_size_show(struct request_queue *q, char *page)
124 {
125         return queue_var_show(queue_logical_block_size(q), page);
126 }
127
128 static ssize_t queue_physical_block_size_show(struct request_queue *q, char *page)
129 {
130         return queue_var_show(queue_physical_block_size(q), page);
131 }
132
133 static ssize_t queue_io_min_show(struct request_queue *q, char *page)
134 {
135         return queue_var_show(queue_io_min(q), page);
136 }
137
138 static ssize_t queue_io_opt_show(struct request_queue *q, char *page)
139 {
140         return queue_var_show(queue_io_opt(q), page);
141 }
142
143 static ssize_t queue_discard_granularity_show(struct request_queue *q, char *page)
144 {
145         return queue_var_show(q->limits.discard_granularity, page);
146 }
147
148 static ssize_t queue_discard_max_show(struct request_queue *q, char *page)
149 {
150         return queue_var_show(q->limits.max_discard_sectors << 9, page);
151 }
152
153 static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page)
154 {
155         return queue_var_show(queue_discard_zeroes_data(q), page);
156 }
157
158 static ssize_t
159 queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
160 {
161         unsigned long max_sectors_kb,
162                 max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1,
163                         page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
164         ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
165
166         if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
167                 return -EINVAL;
168
169         spin_lock_irq(q->queue_lock);
170         q->limits.max_sectors = max_sectors_kb << 1;
171         spin_unlock_irq(q->queue_lock);
172
173         return ret;
174 }
175
176 static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
177 {
178         int max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1;
179
180         return queue_var_show(max_hw_sectors_kb, (page));
181 }
182
183 static ssize_t queue_nonrot_show(struct request_queue *q, char *page)
184 {
185         return queue_var_show(!blk_queue_nonrot(q), page);
186 }
187
188 static ssize_t queue_nonrot_store(struct request_queue *q, const char *page,
189                                   size_t count)
190 {
191         unsigned long nm;
192         ssize_t ret = queue_var_store(&nm, page, count);
193
194         spin_lock_irq(q->queue_lock);
195         if (nm)
196                 queue_flag_clear(QUEUE_FLAG_NONROT, q);
197         else
198                 queue_flag_set(QUEUE_FLAG_NONROT, q);
199         spin_unlock_irq(q->queue_lock);
200
201         return ret;
202 }
203
204 static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
205 {
206         return queue_var_show((blk_queue_nomerges(q) << 1) |
207                                blk_queue_noxmerges(q), page);
208 }
209
210 static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
211                                     size_t count)
212 {
213         unsigned long nm;
214         ssize_t ret = queue_var_store(&nm, page, count);
215
216         spin_lock_irq(q->queue_lock);
217         queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
218         queue_flag_clear(QUEUE_FLAG_NOXMERGES, q);
219         if (nm == 2)
220                 queue_flag_set(QUEUE_FLAG_NOMERGES, q);
221         else if (nm)
222                 queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
223         spin_unlock_irq(q->queue_lock);
224
225         return ret;
226 }
227
228 static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page)
229 {
230         bool set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);
231
232         return queue_var_show(set, page);
233 }
234
235 static ssize_t
236 queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
237 {
238         ssize_t ret = -EINVAL;
239 #if defined(CONFIG_USE_GENERIC_SMP_HELPERS)
240         unsigned long val;
241
242         ret = queue_var_store(&val, page, count);
243         spin_lock_irq(q->queue_lock);
244         if (val)
245                 queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
246         else
247                 queue_flag_clear(QUEUE_FLAG_SAME_COMP,  q);
248         spin_unlock_irq(q->queue_lock);
249 #endif
250         return ret;
251 }
252
253 static ssize_t queue_random_show(struct request_queue *q, char *page)
254 {
255         return queue_var_show(blk_queue_add_random(q), page);
256 }
257
258 static ssize_t queue_random_store(struct request_queue *q, const char *page,
259                                   size_t count)
260 {
261         unsigned long val;
262         ssize_t ret = queue_var_store(&val, page, count);
263
264         spin_lock_irq(q->queue_lock);
265         if (val)
266                 queue_flag_set(QUEUE_FLAG_ADD_RANDOM, q);
267         else
268                 queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, q);
269         spin_unlock_irq(q->queue_lock);
270
271         return ret;
272 }
273
274 static ssize_t queue_iostats_show(struct request_queue *q, char *page)
275 {
276         return queue_var_show(blk_queue_io_stat(q), page);
277 }
278
279 static ssize_t queue_iostats_store(struct request_queue *q, const char *page,
280                                    size_t count)
281 {
282         unsigned long stats;
283         ssize_t ret = queue_var_store(&stats, page, count);
284
285         spin_lock_irq(q->queue_lock);
286         if (stats)
287                 queue_flag_set(QUEUE_FLAG_IO_STAT, q);
288         else
289                 queue_flag_clear(QUEUE_FLAG_IO_STAT, q);
290         spin_unlock_irq(q->queue_lock);
291
292         return ret;
293 }
294
295 static struct queue_sysfs_entry queue_requests_entry = {
296         .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
297         .show = queue_requests_show,
298         .store = queue_requests_store,
299 };
300
301 static struct queue_sysfs_entry queue_ra_entry = {
302         .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
303         .show = queue_ra_show,
304         .store = queue_ra_store,
305 };
306
307 static struct queue_sysfs_entry queue_max_sectors_entry = {
308         .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
309         .show = queue_max_sectors_show,
310         .store = queue_max_sectors_store,
311 };
312
313 static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
314         .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
315         .show = queue_max_hw_sectors_show,
316 };
317
318 static struct queue_sysfs_entry queue_max_segments_entry = {
319         .attr = {.name = "max_segments", .mode = S_IRUGO },
320         .show = queue_max_segments_show,
321 };
322
323 static struct queue_sysfs_entry queue_max_segment_size_entry = {
324         .attr = {.name = "max_segment_size", .mode = S_IRUGO },
325         .show = queue_max_segment_size_show,
326 };
327
328 static struct queue_sysfs_entry queue_iosched_entry = {
329         .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
330         .show = elv_iosched_show,
331         .store = elv_iosched_store,
332 };
333
334 static struct queue_sysfs_entry queue_hw_sector_size_entry = {
335         .attr = {.name = "hw_sector_size", .mode = S_IRUGO },
336         .show = queue_logical_block_size_show,
337 };
338
339 static struct queue_sysfs_entry queue_logical_block_size_entry = {
340         .attr = {.name = "logical_block_size", .mode = S_IRUGO },
341         .show = queue_logical_block_size_show,
342 };
343
344 static struct queue_sysfs_entry queue_physical_block_size_entry = {
345         .attr = {.name = "physical_block_size", .mode = S_IRUGO },
346         .show = queue_physical_block_size_show,
347 };
348
349 static struct queue_sysfs_entry queue_io_min_entry = {
350         .attr = {.name = "minimum_io_size", .mode = S_IRUGO },
351         .show = queue_io_min_show,
352 };
353
354 static struct queue_sysfs_entry queue_io_opt_entry = {
355         .attr = {.name = "optimal_io_size", .mode = S_IRUGO },
356         .show = queue_io_opt_show,
357 };
358
359 static struct queue_sysfs_entry queue_discard_granularity_entry = {
360         .attr = {.name = "discard_granularity", .mode = S_IRUGO },
361         .show = queue_discard_granularity_show,
362 };
363
364 static struct queue_sysfs_entry queue_discard_max_entry = {
365         .attr = {.name = "discard_max_bytes", .mode = S_IRUGO },
366         .show = queue_discard_max_show,
367 };
368
369 static struct queue_sysfs_entry queue_discard_zeroes_data_entry = {
370         .attr = {.name = "discard_zeroes_data", .mode = S_IRUGO },
371         .show = queue_discard_zeroes_data_show,
372 };
373
374 static struct queue_sysfs_entry queue_nonrot_entry = {
375         .attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR },
376         .show = queue_nonrot_show,
377         .store = queue_nonrot_store,
378 };
379
380 static struct queue_sysfs_entry queue_nomerges_entry = {
381         .attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
382         .show = queue_nomerges_show,
383         .store = queue_nomerges_store,
384 };
385
386 static struct queue_sysfs_entry queue_rq_affinity_entry = {
387         .attr = {.name = "rq_affinity", .mode = S_IRUGO | S_IWUSR },
388         .show = queue_rq_affinity_show,
389         .store = queue_rq_affinity_store,
390 };
391
392 static struct queue_sysfs_entry queue_iostats_entry = {
393         .attr = {.name = "iostats", .mode = S_IRUGO | S_IWUSR },
394         .show = queue_iostats_show,
395         .store = queue_iostats_store,
396 };
397
398 static struct queue_sysfs_entry queue_random_entry = {
399         .attr = {.name = "add_random", .mode = S_IRUGO | S_IWUSR },
400         .show = queue_random_show,
401         .store = queue_random_store,
402 };
403
404 static struct attribute *default_attrs[] = {
405         &queue_requests_entry.attr,
406         &queue_ra_entry.attr,
407         &queue_max_hw_sectors_entry.attr,
408         &queue_max_sectors_entry.attr,
409         &queue_max_segments_entry.attr,
410         &queue_max_segment_size_entry.attr,
411         &queue_iosched_entry.attr,
412         &queue_hw_sector_size_entry.attr,
413         &queue_logical_block_size_entry.attr,
414         &queue_physical_block_size_entry.attr,
415         &queue_io_min_entry.attr,
416         &queue_io_opt_entry.attr,
417         &queue_discard_granularity_entry.attr,
418         &queue_discard_max_entry.attr,
419         &queue_discard_zeroes_data_entry.attr,
420         &queue_nonrot_entry.attr,
421         &queue_nomerges_entry.attr,
422         &queue_rq_affinity_entry.attr,
423         &queue_iostats_entry.attr,
424         &queue_random_entry.attr,
425         NULL,
426 };
427
428 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
429
430 static ssize_t
431 queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
432 {
433         struct queue_sysfs_entry *entry = to_queue(attr);
434         struct request_queue *q =
435                 container_of(kobj, struct request_queue, kobj);
436         ssize_t res;
437
438         if (!entry->show)
439                 return -EIO;
440         mutex_lock(&q->sysfs_lock);
441         if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
442                 mutex_unlock(&q->sysfs_lock);
443                 return -ENOENT;
444         }
445         res = entry->show(q, page);
446         mutex_unlock(&q->sysfs_lock);
447         return res;
448 }
449
450 static ssize_t
451 queue_attr_store(struct kobject *kobj, struct attribute *attr,
452                     const char *page, size_t length)
453 {
454         struct queue_sysfs_entry *entry = to_queue(attr);
455         struct request_queue *q;
456         ssize_t res;
457
458         if (!entry->store)
459                 return -EIO;
460
461         q = container_of(kobj, struct request_queue, kobj);
462         mutex_lock(&q->sysfs_lock);
463         if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
464                 mutex_unlock(&q->sysfs_lock);
465                 return -ENOENT;
466         }
467         res = entry->store(q, page, length);
468         mutex_unlock(&q->sysfs_lock);
469         return res;
470 }
471
472 /**
473  * blk_cleanup_queue: - release a &struct request_queue when it is no longer needed
474  * @kobj:    the kobj belonging of the request queue to be released
475  *
476  * Description:
477  *     blk_cleanup_queue is the pair to blk_init_queue() or
478  *     blk_queue_make_request().  It should be called when a request queue is
479  *     being released; typically when a block device is being de-registered.
480  *     Currently, its primary task it to free all the &struct request
481  *     structures that were allocated to the queue and the queue itself.
482  *
483  * Caveat:
484  *     Hopefully the low level driver will have finished any
485  *     outstanding requests first...
486  **/
487 static void blk_release_queue(struct kobject *kobj)
488 {
489         struct request_queue *q =
490                 container_of(kobj, struct request_queue, kobj);
491         struct request_list *rl = &q->rq;
492
493         blk_sync_queue(q);
494
495         if (rl->rq_pool)
496                 mempool_destroy(rl->rq_pool);
497
498         if (q->queue_tags)
499                 __blk_queue_free_tags(q);
500
501         blk_trace_shutdown(q);
502
503         bdi_destroy(&q->backing_dev_info);
504         kmem_cache_free(blk_requestq_cachep, q);
505 }
506
507 static const struct sysfs_ops queue_sysfs_ops = {
508         .show   = queue_attr_show,
509         .store  = queue_attr_store,
510 };
511
512 struct kobj_type blk_queue_ktype = {
513         .sysfs_ops      = &queue_sysfs_ops,
514         .default_attrs  = default_attrs,
515         .release        = blk_release_queue,
516 };
517
518 int blk_register_queue(struct gendisk *disk)
519 {
520         int ret;
521         struct device *dev = disk_to_dev(disk);
522
523         struct request_queue *q = disk->queue;
524
525         if (WARN_ON(!q))
526                 return -ENXIO;
527
528         ret = blk_trace_init_sysfs(dev);
529         if (ret)
530                 return ret;
531
532         ret = kobject_add(&q->kobj, kobject_get(&dev->kobj), "%s", "queue");
533         if (ret < 0)
534                 return ret;
535
536         kobject_uevent(&q->kobj, KOBJ_ADD);
537
538         if (!q->request_fn)
539                 return 0;
540
541         ret = elv_register_queue(q);
542         if (ret) {
543                 kobject_uevent(&q->kobj, KOBJ_REMOVE);
544                 kobject_del(&q->kobj);
545                 blk_trace_remove_sysfs(disk_to_dev(disk));
546                 return ret;
547         }
548
549         return 0;
550 }
551
552 void blk_unregister_queue(struct gendisk *disk)
553 {
554         struct request_queue *q = disk->queue;
555
556         if (WARN_ON(!q))
557                 return;
558
559         if (q->request_fn)
560                 elv_unregister_queue(q);
561
562         kobject_uevent(&q->kobj, KOBJ_REMOVE);
563         kobject_del(&q->kobj);
564         blk_trace_remove_sysfs(disk_to_dev(disk));
565         kobject_put(&disk_to_dev(disk)->kobj);
566 }