block: simplify I/O stat accounting
[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 int var, char *page)
20 {
21         return sprintf(page, "%d\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 = queue_var_store(&nr, page, count);
44         if (nr < BLKDEV_MIN_RQ)
45                 nr = BLKDEV_MIN_RQ;
46
47         spin_lock_irq(q->queue_lock);
48         q->nr_requests = nr;
49         blk_queue_congestion_threshold(q);
50
51         if (rl->count[BLK_RW_SYNC] >= queue_congestion_on_threshold(q))
52                 blk_set_queue_congested(q, BLK_RW_SYNC);
53         else if (rl->count[BLK_RW_SYNC] < queue_congestion_off_threshold(q))
54                 blk_clear_queue_congested(q, BLK_RW_SYNC);
55
56         if (rl->count[BLK_RW_ASYNC] >= queue_congestion_on_threshold(q))
57                 blk_set_queue_congested(q, BLK_RW_ASYNC);
58         else if (rl->count[BLK_RW_ASYNC] < queue_congestion_off_threshold(q))
59                 blk_clear_queue_congested(q, BLK_RW_ASYNC);
60
61         if (rl->count[BLK_RW_SYNC] >= q->nr_requests) {
62                 blk_set_queue_full(q, BLK_RW_SYNC);
63         } else if (rl->count[BLK_RW_SYNC]+1 <= q->nr_requests) {
64                 blk_clear_queue_full(q, BLK_RW_SYNC);
65                 wake_up(&rl->wait[BLK_RW_SYNC]);
66         }
67
68         if (rl->count[BLK_RW_ASYNC] >= q->nr_requests) {
69                 blk_set_queue_full(q, BLK_RW_ASYNC);
70         } else if (rl->count[BLK_RW_ASYNC]+1 <= q->nr_requests) {
71                 blk_clear_queue_full(q, BLK_RW_ASYNC);
72                 wake_up(&rl->wait[BLK_RW_ASYNC]);
73         }
74         spin_unlock_irq(q->queue_lock);
75         return ret;
76 }
77
78 static ssize_t queue_ra_show(struct request_queue *q, char *page)
79 {
80         int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
81
82         return queue_var_show(ra_kb, (page));
83 }
84
85 static ssize_t
86 queue_ra_store(struct request_queue *q, const char *page, size_t count)
87 {
88         unsigned long ra_kb;
89         ssize_t ret = queue_var_store(&ra_kb, page, count);
90
91         q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);
92
93         return ret;
94 }
95
96 static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
97 {
98         int max_sectors_kb = q->max_sectors >> 1;
99
100         return queue_var_show(max_sectors_kb, (page));
101 }
102
103 static ssize_t queue_hw_sector_size_show(struct request_queue *q, char *page)
104 {
105         return queue_var_show(q->hardsect_size, page);
106 }
107
108 static ssize_t
109 queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
110 {
111         unsigned long max_sectors_kb,
112                         max_hw_sectors_kb = q->max_hw_sectors >> 1,
113                         page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
114         ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
115
116         if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
117                 return -EINVAL;
118
119         spin_lock_irq(q->queue_lock);
120         q->max_sectors = max_sectors_kb << 1;
121         spin_unlock_irq(q->queue_lock);
122
123         return ret;
124 }
125
126 static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
127 {
128         int max_hw_sectors_kb = q->max_hw_sectors >> 1;
129
130         return queue_var_show(max_hw_sectors_kb, (page));
131 }
132
133 static ssize_t queue_nonrot_show(struct request_queue *q, char *page)
134 {
135         return queue_var_show(!blk_queue_nonrot(q), page);
136 }
137
138 static ssize_t queue_nonrot_store(struct request_queue *q, const char *page,
139                                   size_t count)
140 {
141         unsigned long nm;
142         ssize_t ret = queue_var_store(&nm, page, count);
143
144         spin_lock_irq(q->queue_lock);
145         if (nm)
146                 queue_flag_clear(QUEUE_FLAG_NONROT, q);
147         else
148                 queue_flag_set(QUEUE_FLAG_NONROT, q);
149         spin_unlock_irq(q->queue_lock);
150
151         return ret;
152 }
153
154 static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
155 {
156         return queue_var_show(blk_queue_nomerges(q), page);
157 }
158
159 static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
160                                     size_t count)
161 {
162         unsigned long nm;
163         ssize_t ret = queue_var_store(&nm, page, count);
164
165         spin_lock_irq(q->queue_lock);
166         if (nm)
167                 queue_flag_set(QUEUE_FLAG_NOMERGES, q);
168         else
169                 queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
170         spin_unlock_irq(q->queue_lock);
171
172         return ret;
173 }
174
175 static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page)
176 {
177         unsigned int set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);
178
179         return queue_var_show(set != 0, page);
180 }
181
182 static ssize_t
183 queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
184 {
185         ssize_t ret = -EINVAL;
186 #if defined(CONFIG_USE_GENERIC_SMP_HELPERS)
187         unsigned long val;
188
189         ret = queue_var_store(&val, page, count);
190         spin_lock_irq(q->queue_lock);
191         if (val)
192                 queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
193         else
194                 queue_flag_clear(QUEUE_FLAG_SAME_COMP,  q);
195         spin_unlock_irq(q->queue_lock);
196 #endif
197         return ret;
198 }
199
200 static ssize_t queue_iostats_show(struct request_queue *q, char *page)
201 {
202         return queue_var_show(blk_queue_io_stat(q), page);
203 }
204
205 static ssize_t queue_iostats_store(struct request_queue *q, const char *page,
206                                    size_t count)
207 {
208         unsigned long stats;
209         ssize_t ret = queue_var_store(&stats, page, count);
210
211         spin_lock_irq(q->queue_lock);
212         if (stats)
213                 queue_flag_set(QUEUE_FLAG_IO_STAT, q);
214         else
215                 queue_flag_clear(QUEUE_FLAG_IO_STAT, q);
216         spin_unlock_irq(q->queue_lock);
217
218         return ret;
219 }
220
221 static struct queue_sysfs_entry queue_requests_entry = {
222         .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
223         .show = queue_requests_show,
224         .store = queue_requests_store,
225 };
226
227 static struct queue_sysfs_entry queue_ra_entry = {
228         .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
229         .show = queue_ra_show,
230         .store = queue_ra_store,
231 };
232
233 static struct queue_sysfs_entry queue_max_sectors_entry = {
234         .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
235         .show = queue_max_sectors_show,
236         .store = queue_max_sectors_store,
237 };
238
239 static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
240         .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
241         .show = queue_max_hw_sectors_show,
242 };
243
244 static struct queue_sysfs_entry queue_iosched_entry = {
245         .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
246         .show = elv_iosched_show,
247         .store = elv_iosched_store,
248 };
249
250 static struct queue_sysfs_entry queue_hw_sector_size_entry = {
251         .attr = {.name = "hw_sector_size", .mode = S_IRUGO },
252         .show = queue_hw_sector_size_show,
253 };
254
255 static struct queue_sysfs_entry queue_nonrot_entry = {
256         .attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR },
257         .show = queue_nonrot_show,
258         .store = queue_nonrot_store,
259 };
260
261 static struct queue_sysfs_entry queue_nomerges_entry = {
262         .attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
263         .show = queue_nomerges_show,
264         .store = queue_nomerges_store,
265 };
266
267 static struct queue_sysfs_entry queue_rq_affinity_entry = {
268         .attr = {.name = "rq_affinity", .mode = S_IRUGO | S_IWUSR },
269         .show = queue_rq_affinity_show,
270         .store = queue_rq_affinity_store,
271 };
272
273 static struct queue_sysfs_entry queue_iostats_entry = {
274         .attr = {.name = "iostats", .mode = S_IRUGO | S_IWUSR },
275         .show = queue_iostats_show,
276         .store = queue_iostats_store,
277 };
278
279 static struct attribute *default_attrs[] = {
280         &queue_requests_entry.attr,
281         &queue_ra_entry.attr,
282         &queue_max_hw_sectors_entry.attr,
283         &queue_max_sectors_entry.attr,
284         &queue_iosched_entry.attr,
285         &queue_hw_sector_size_entry.attr,
286         &queue_nonrot_entry.attr,
287         &queue_nomerges_entry.attr,
288         &queue_rq_affinity_entry.attr,
289         &queue_iostats_entry.attr,
290         NULL,
291 };
292
293 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
294
295 static ssize_t
296 queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
297 {
298         struct queue_sysfs_entry *entry = to_queue(attr);
299         struct request_queue *q =
300                 container_of(kobj, struct request_queue, kobj);
301         ssize_t res;
302
303         if (!entry->show)
304                 return -EIO;
305         mutex_lock(&q->sysfs_lock);
306         if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
307                 mutex_unlock(&q->sysfs_lock);
308                 return -ENOENT;
309         }
310         res = entry->show(q, page);
311         mutex_unlock(&q->sysfs_lock);
312         return res;
313 }
314
315 static ssize_t
316 queue_attr_store(struct kobject *kobj, struct attribute *attr,
317                     const char *page, size_t length)
318 {
319         struct queue_sysfs_entry *entry = to_queue(attr);
320         struct request_queue *q;
321         ssize_t res;
322
323         if (!entry->store)
324                 return -EIO;
325
326         q = container_of(kobj, struct request_queue, kobj);
327         mutex_lock(&q->sysfs_lock);
328         if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
329                 mutex_unlock(&q->sysfs_lock);
330                 return -ENOENT;
331         }
332         res = entry->store(q, page, length);
333         mutex_unlock(&q->sysfs_lock);
334         return res;
335 }
336
337 /**
338  * blk_cleanup_queue: - release a &struct request_queue when it is no longer needed
339  * @kobj:    the kobj belonging of the request queue to be released
340  *
341  * Description:
342  *     blk_cleanup_queue is the pair to blk_init_queue() or
343  *     blk_queue_make_request().  It should be called when a request queue is
344  *     being released; typically when a block device is being de-registered.
345  *     Currently, its primary task it to free all the &struct request
346  *     structures that were allocated to the queue and the queue itself.
347  *
348  * Caveat:
349  *     Hopefully the low level driver will have finished any
350  *     outstanding requests first...
351  **/
352 static void blk_release_queue(struct kobject *kobj)
353 {
354         struct request_queue *q =
355                 container_of(kobj, struct request_queue, kobj);
356         struct request_list *rl = &q->rq;
357
358         blk_sync_queue(q);
359
360         if (rl->rq_pool)
361                 mempool_destroy(rl->rq_pool);
362
363         if (q->queue_tags)
364                 __blk_queue_free_tags(q);
365
366         blk_trace_shutdown(q);
367
368         bdi_destroy(&q->backing_dev_info);
369         kmem_cache_free(blk_requestq_cachep, q);
370 }
371
372 static struct sysfs_ops queue_sysfs_ops = {
373         .show   = queue_attr_show,
374         .store  = queue_attr_store,
375 };
376
377 struct kobj_type blk_queue_ktype = {
378         .sysfs_ops      = &queue_sysfs_ops,
379         .default_attrs  = default_attrs,
380         .release        = blk_release_queue,
381 };
382
383 int blk_register_queue(struct gendisk *disk)
384 {
385         int ret;
386
387         struct request_queue *q = disk->queue;
388
389         if (WARN_ON(!q))
390                 return -ENXIO;
391
392         if (!q->request_fn)
393                 return 0;
394
395         ret = kobject_add(&q->kobj, kobject_get(&disk_to_dev(disk)->kobj),
396                           "%s", "queue");
397         if (ret < 0)
398                 return ret;
399
400         kobject_uevent(&q->kobj, KOBJ_ADD);
401
402         ret = elv_register_queue(q);
403         if (ret) {
404                 kobject_uevent(&q->kobj, KOBJ_REMOVE);
405                 kobject_del(&q->kobj);
406                 return ret;
407         }
408
409         return 0;
410 }
411
412 void blk_unregister_queue(struct gendisk *disk)
413 {
414         struct request_queue *q = disk->queue;
415
416         if (WARN_ON(!q))
417                 return;
418
419         if (q->request_fn) {
420                 elv_unregister_queue(q);
421
422                 kobject_uevent(&q->kobj, KOBJ_REMOVE);
423                 kobject_del(&q->kobj);
424                 kobject_put(&disk_to_dev(disk)->kobj);
425         }
426 }