block: don't take lock on changing ra_pages
[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[READ] >= queue_congestion_on_threshold(q))
52                 blk_set_queue_congested(q, READ);
53         else if (rl->count[READ] < queue_congestion_off_threshold(q))
54                 blk_clear_queue_congested(q, READ);
55
56         if (rl->count[WRITE] >= queue_congestion_on_threshold(q))
57                 blk_set_queue_congested(q, WRITE);
58         else if (rl->count[WRITE] < queue_congestion_off_threshold(q))
59                 blk_clear_queue_congested(q, WRITE);
60
61         if (rl->count[READ] >= q->nr_requests) {
62                 blk_set_queue_full(q, READ);
63         } else if (rl->count[READ]+1 <= q->nr_requests) {
64                 blk_clear_queue_full(q, READ);
65                 wake_up(&rl->wait[READ]);
66         }
67
68         if (rl->count[WRITE] >= q->nr_requests) {
69                 blk_set_queue_full(q, WRITE);
70         } else if (rl->count[WRITE]+1 <= q->nr_requests) {
71                 blk_clear_queue_full(q, WRITE);
72                 wake_up(&rl->wait[WRITE]);
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_nomerges_show(struct request_queue *q, char *page)
134 {
135         return queue_var_show(blk_queue_nomerges(q), page);
136 }
137
138 static ssize_t queue_nomerges_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_set(QUEUE_FLAG_NOMERGES, q);
147         else
148                 queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
149
150         spin_unlock_irq(q->queue_lock);
151         return ret;
152 }
153
154 static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page)
155 {
156         unsigned int set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);
157
158         return queue_var_show(set != 0, page);
159 }
160
161 static ssize_t
162 queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
163 {
164         ssize_t ret = -EINVAL;
165 #if defined(CONFIG_USE_GENERIC_SMP_HELPERS)
166         unsigned long val;
167
168         ret = queue_var_store(&val, page, count);
169         spin_lock_irq(q->queue_lock);
170         if (val)
171                 queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
172         else
173                 queue_flag_clear(QUEUE_FLAG_SAME_COMP,  q);
174         spin_unlock_irq(q->queue_lock);
175 #endif
176         return ret;
177 }
178
179 static struct queue_sysfs_entry queue_requests_entry = {
180         .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
181         .show = queue_requests_show,
182         .store = queue_requests_store,
183 };
184
185 static struct queue_sysfs_entry queue_ra_entry = {
186         .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
187         .show = queue_ra_show,
188         .store = queue_ra_store,
189 };
190
191 static struct queue_sysfs_entry queue_max_sectors_entry = {
192         .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
193         .show = queue_max_sectors_show,
194         .store = queue_max_sectors_store,
195 };
196
197 static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
198         .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
199         .show = queue_max_hw_sectors_show,
200 };
201
202 static struct queue_sysfs_entry queue_iosched_entry = {
203         .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
204         .show = elv_iosched_show,
205         .store = elv_iosched_store,
206 };
207
208 static struct queue_sysfs_entry queue_hw_sector_size_entry = {
209         .attr = {.name = "hw_sector_size", .mode = S_IRUGO },
210         .show = queue_hw_sector_size_show,
211 };
212
213 static struct queue_sysfs_entry queue_nomerges_entry = {
214         .attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
215         .show = queue_nomerges_show,
216         .store = queue_nomerges_store,
217 };
218
219 static struct queue_sysfs_entry queue_rq_affinity_entry = {
220         .attr = {.name = "rq_affinity", .mode = S_IRUGO | S_IWUSR },
221         .show = queue_rq_affinity_show,
222         .store = queue_rq_affinity_store,
223 };
224
225 static struct attribute *default_attrs[] = {
226         &queue_requests_entry.attr,
227         &queue_ra_entry.attr,
228         &queue_max_hw_sectors_entry.attr,
229         &queue_max_sectors_entry.attr,
230         &queue_iosched_entry.attr,
231         &queue_hw_sector_size_entry.attr,
232         &queue_nomerges_entry.attr,
233         &queue_rq_affinity_entry.attr,
234         NULL,
235 };
236
237 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
238
239 static ssize_t
240 queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
241 {
242         struct queue_sysfs_entry *entry = to_queue(attr);
243         struct request_queue *q =
244                 container_of(kobj, struct request_queue, kobj);
245         ssize_t res;
246
247         if (!entry->show)
248                 return -EIO;
249         mutex_lock(&q->sysfs_lock);
250         if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
251                 mutex_unlock(&q->sysfs_lock);
252                 return -ENOENT;
253         }
254         res = entry->show(q, page);
255         mutex_unlock(&q->sysfs_lock);
256         return res;
257 }
258
259 static ssize_t
260 queue_attr_store(struct kobject *kobj, struct attribute *attr,
261                     const char *page, size_t length)
262 {
263         struct queue_sysfs_entry *entry = to_queue(attr);
264         struct request_queue *q;
265         ssize_t res;
266
267         if (!entry->store)
268                 return -EIO;
269
270         q = container_of(kobj, struct request_queue, kobj);
271         mutex_lock(&q->sysfs_lock);
272         if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
273                 mutex_unlock(&q->sysfs_lock);
274                 return -ENOENT;
275         }
276         res = entry->store(q, page, length);
277         mutex_unlock(&q->sysfs_lock);
278         return res;
279 }
280
281 /**
282  * blk_cleanup_queue: - release a &struct request_queue when it is no longer needed
283  * @kobj:    the kobj belonging of the request queue to be released
284  *
285  * Description:
286  *     blk_cleanup_queue is the pair to blk_init_queue() or
287  *     blk_queue_make_request().  It should be called when a request queue is
288  *     being released; typically when a block device is being de-registered.
289  *     Currently, its primary task it to free all the &struct request
290  *     structures that were allocated to the queue and the queue itself.
291  *
292  * Caveat:
293  *     Hopefully the low level driver will have finished any
294  *     outstanding requests first...
295  **/
296 static void blk_release_queue(struct kobject *kobj)
297 {
298         struct request_queue *q =
299                 container_of(kobj, struct request_queue, kobj);
300         struct request_list *rl = &q->rq;
301
302         blk_sync_queue(q);
303
304         if (rl->rq_pool)
305                 mempool_destroy(rl->rq_pool);
306
307         if (q->queue_tags)
308                 __blk_queue_free_tags(q);
309
310         blk_trace_shutdown(q);
311
312         bdi_destroy(&q->backing_dev_info);
313         kmem_cache_free(blk_requestq_cachep, q);
314 }
315
316 static struct sysfs_ops queue_sysfs_ops = {
317         .show   = queue_attr_show,
318         .store  = queue_attr_store,
319 };
320
321 struct kobj_type blk_queue_ktype = {
322         .sysfs_ops      = &queue_sysfs_ops,
323         .default_attrs  = default_attrs,
324         .release        = blk_release_queue,
325 };
326
327 int blk_register_queue(struct gendisk *disk)
328 {
329         int ret;
330
331         struct request_queue *q = disk->queue;
332
333         if (WARN_ON(!q))
334                 return -ENXIO;
335
336         if (!q->request_fn)
337                 return 0;
338
339         ret = kobject_add(&q->kobj, kobject_get(&disk_to_dev(disk)->kobj),
340                           "%s", "queue");
341         if (ret < 0)
342                 return ret;
343
344         kobject_uevent(&q->kobj, KOBJ_ADD);
345
346         ret = elv_register_queue(q);
347         if (ret) {
348                 kobject_uevent(&q->kobj, KOBJ_REMOVE);
349                 kobject_del(&q->kobj);
350                 return ret;
351         }
352
353         return 0;
354 }
355
356 void blk_unregister_queue(struct gendisk *disk)
357 {
358         struct request_queue *q = disk->queue;
359
360         if (WARN_ON(!q))
361                 return;
362
363         if (q->request_fn) {
364                 elv_unregister_queue(q);
365
366                 kobject_uevent(&q->kobj, KOBJ_REMOVE);
367                 kobject_del(&q->kobj);
368                 kobject_put(&disk_to_dev(disk)->kobj);
369         }
370 }