block: Skip I/O merges when disabled
[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         spin_lock_irq(q->queue_lock);
92         q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);
93         spin_unlock_irq(q->queue_lock);
94
95         return ret;
96 }
97
98 static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
99 {
100         int max_sectors_kb = q->max_sectors >> 1;
101
102         return queue_var_show(max_sectors_kb, (page));
103 }
104
105 static ssize_t queue_hw_sector_size_show(struct request_queue *q, char *page)
106 {
107         return queue_var_show(q->hardsect_size, page);
108 }
109
110 static ssize_t
111 queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
112 {
113         unsigned long max_sectors_kb,
114                         max_hw_sectors_kb = q->max_hw_sectors >> 1,
115                         page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
116         ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
117
118         if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
119                 return -EINVAL;
120         /*
121          * Take the queue lock to update the readahead and max_sectors
122          * values synchronously:
123          */
124         spin_lock_irq(q->queue_lock);
125         q->max_sectors = max_sectors_kb << 1;
126         spin_unlock_irq(q->queue_lock);
127
128         return ret;
129 }
130
131 static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
132 {
133         int max_hw_sectors_kb = q->max_hw_sectors >> 1;
134
135         return queue_var_show(max_hw_sectors_kb, (page));
136 }
137
138 static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
139 {
140         return queue_var_show(blk_queue_nomerges(q), page);
141 }
142
143 static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
144                                     size_t count)
145 {
146         unsigned long nm;
147         ssize_t ret = queue_var_store(&nm, page, count);
148
149         if (nm)
150                set_bit(QUEUE_FLAG_NOMERGES, &q->queue_flags);
151         else
152                clear_bit(QUEUE_FLAG_NOMERGES, &q->queue_flags);
153
154         return ret;
155 }
156
157
158 static struct queue_sysfs_entry queue_requests_entry = {
159         .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
160         .show = queue_requests_show,
161         .store = queue_requests_store,
162 };
163
164 static struct queue_sysfs_entry queue_ra_entry = {
165         .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
166         .show = queue_ra_show,
167         .store = queue_ra_store,
168 };
169
170 static struct queue_sysfs_entry queue_max_sectors_entry = {
171         .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
172         .show = queue_max_sectors_show,
173         .store = queue_max_sectors_store,
174 };
175
176 static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
177         .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
178         .show = queue_max_hw_sectors_show,
179 };
180
181 static struct queue_sysfs_entry queue_iosched_entry = {
182         .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
183         .show = elv_iosched_show,
184         .store = elv_iosched_store,
185 };
186
187 static struct queue_sysfs_entry queue_hw_sector_size_entry = {
188         .attr = {.name = "hw_sector_size", .mode = S_IRUGO },
189         .show = queue_hw_sector_size_show,
190 };
191
192 static struct queue_sysfs_entry queue_nomerges_entry = {
193         .attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
194         .show = queue_nomerges_show,
195         .store = queue_nomerges_store,
196 };
197
198 static struct attribute *default_attrs[] = {
199         &queue_requests_entry.attr,
200         &queue_ra_entry.attr,
201         &queue_max_hw_sectors_entry.attr,
202         &queue_max_sectors_entry.attr,
203         &queue_iosched_entry.attr,
204         &queue_hw_sector_size_entry.attr,
205         &queue_nomerges_entry.attr,
206         NULL,
207 };
208
209 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
210
211 static ssize_t
212 queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
213 {
214         struct queue_sysfs_entry *entry = to_queue(attr);
215         struct request_queue *q =
216                 container_of(kobj, struct request_queue, kobj);
217         ssize_t res;
218
219         if (!entry->show)
220                 return -EIO;
221         mutex_lock(&q->sysfs_lock);
222         if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
223                 mutex_unlock(&q->sysfs_lock);
224                 return -ENOENT;
225         }
226         res = entry->show(q, page);
227         mutex_unlock(&q->sysfs_lock);
228         return res;
229 }
230
231 static ssize_t
232 queue_attr_store(struct kobject *kobj, struct attribute *attr,
233                     const char *page, size_t length)
234 {
235         struct queue_sysfs_entry *entry = to_queue(attr);
236         struct request_queue *q;
237         ssize_t res;
238
239         if (!entry->store)
240                 return -EIO;
241
242         q = container_of(kobj, struct request_queue, kobj);
243         mutex_lock(&q->sysfs_lock);
244         if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
245                 mutex_unlock(&q->sysfs_lock);
246                 return -ENOENT;
247         }
248         res = entry->store(q, page, length);
249         mutex_unlock(&q->sysfs_lock);
250         return res;
251 }
252
253 /**
254  * blk_cleanup_queue: - release a &struct request_queue when it is no longer needed
255  * @kobj:    the kobj belonging of the request queue to be released
256  *
257  * Description:
258  *     blk_cleanup_queue is the pair to blk_init_queue() or
259  *     blk_queue_make_request().  It should be called when a request queue is
260  *     being released; typically when a block device is being de-registered.
261  *     Currently, its primary task it to free all the &struct request
262  *     structures that were allocated to the queue and the queue itself.
263  *
264  * Caveat:
265  *     Hopefully the low level driver will have finished any
266  *     outstanding requests first...
267  **/
268 static void blk_release_queue(struct kobject *kobj)
269 {
270         struct request_queue *q =
271                 container_of(kobj, struct request_queue, kobj);
272         struct request_list *rl = &q->rq;
273
274         blk_sync_queue(q);
275
276         if (rl->rq_pool)
277                 mempool_destroy(rl->rq_pool);
278
279         if (q->queue_tags)
280                 __blk_queue_free_tags(q);
281
282         blk_trace_shutdown(q);
283
284         bdi_destroy(&q->backing_dev_info);
285         kmem_cache_free(blk_requestq_cachep, q);
286 }
287
288 static struct sysfs_ops queue_sysfs_ops = {
289         .show   = queue_attr_show,
290         .store  = queue_attr_store,
291 };
292
293 struct kobj_type blk_queue_ktype = {
294         .sysfs_ops      = &queue_sysfs_ops,
295         .default_attrs  = default_attrs,
296         .release        = blk_release_queue,
297 };
298
299 int blk_register_queue(struct gendisk *disk)
300 {
301         int ret;
302
303         struct request_queue *q = disk->queue;
304
305         if (WARN_ON(!q))
306                 return -ENXIO;
307
308         if (!q->request_fn)
309                 return 0;
310
311         ret = kobject_add(&q->kobj, kobject_get(&disk->dev.kobj),
312                           "%s", "queue");
313         if (ret < 0)
314                 return ret;
315
316         kobject_uevent(&q->kobj, KOBJ_ADD);
317
318         ret = elv_register_queue(q);
319         if (ret) {
320                 kobject_uevent(&q->kobj, KOBJ_REMOVE);
321                 kobject_del(&q->kobj);
322                 return ret;
323         }
324
325         return 0;
326 }
327
328 void blk_unregister_queue(struct gendisk *disk)
329 {
330         struct request_queue *q = disk->queue;
331
332         if (WARN_ON(!q))
333                 return;
334
335         if (q->request_fn) {
336                 elv_unregister_queue(q);
337
338                 kobject_uevent(&q->kobj, KOBJ_REMOVE);
339                 kobject_del(&q->kobj);
340                 kobject_put(&disk->dev.kobj);
341         }
342 }