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