xref: /openbmc/linux/block/blk-sysfs.c (revision 22246614)
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 	spin_lock_irq(q->queue_lock);
150 	if (nm)
151 		queue_flag_set(QUEUE_FLAG_NOMERGES, q);
152 	else
153 		queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
154 
155 	spin_unlock_irq(q->queue_lock);
156 	return ret;
157 }
158 
159 
160 static struct queue_sysfs_entry queue_requests_entry = {
161 	.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
162 	.show = queue_requests_show,
163 	.store = queue_requests_store,
164 };
165 
166 static struct queue_sysfs_entry queue_ra_entry = {
167 	.attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
168 	.show = queue_ra_show,
169 	.store = queue_ra_store,
170 };
171 
172 static struct queue_sysfs_entry queue_max_sectors_entry = {
173 	.attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
174 	.show = queue_max_sectors_show,
175 	.store = queue_max_sectors_store,
176 };
177 
178 static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
179 	.attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
180 	.show = queue_max_hw_sectors_show,
181 };
182 
183 static struct queue_sysfs_entry queue_iosched_entry = {
184 	.attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
185 	.show = elv_iosched_show,
186 	.store = elv_iosched_store,
187 };
188 
189 static struct queue_sysfs_entry queue_hw_sector_size_entry = {
190 	.attr = {.name = "hw_sector_size", .mode = S_IRUGO },
191 	.show = queue_hw_sector_size_show,
192 };
193 
194 static struct queue_sysfs_entry queue_nomerges_entry = {
195 	.attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
196 	.show = queue_nomerges_show,
197 	.store = queue_nomerges_store,
198 };
199 
200 static struct attribute *default_attrs[] = {
201 	&queue_requests_entry.attr,
202 	&queue_ra_entry.attr,
203 	&queue_max_hw_sectors_entry.attr,
204 	&queue_max_sectors_entry.attr,
205 	&queue_iosched_entry.attr,
206 	&queue_hw_sector_size_entry.attr,
207 	&queue_nomerges_entry.attr,
208 	NULL,
209 };
210 
211 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
212 
213 static ssize_t
214 queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
215 {
216 	struct queue_sysfs_entry *entry = to_queue(attr);
217 	struct request_queue *q =
218 		container_of(kobj, struct request_queue, kobj);
219 	ssize_t res;
220 
221 	if (!entry->show)
222 		return -EIO;
223 	mutex_lock(&q->sysfs_lock);
224 	if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
225 		mutex_unlock(&q->sysfs_lock);
226 		return -ENOENT;
227 	}
228 	res = entry->show(q, page);
229 	mutex_unlock(&q->sysfs_lock);
230 	return res;
231 }
232 
233 static ssize_t
234 queue_attr_store(struct kobject *kobj, struct attribute *attr,
235 		    const char *page, size_t length)
236 {
237 	struct queue_sysfs_entry *entry = to_queue(attr);
238 	struct request_queue *q;
239 	ssize_t res;
240 
241 	if (!entry->store)
242 		return -EIO;
243 
244 	q = container_of(kobj, struct request_queue, kobj);
245 	mutex_lock(&q->sysfs_lock);
246 	if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
247 		mutex_unlock(&q->sysfs_lock);
248 		return -ENOENT;
249 	}
250 	res = entry->store(q, page, length);
251 	mutex_unlock(&q->sysfs_lock);
252 	return res;
253 }
254 
255 /**
256  * blk_cleanup_queue: - release a &struct request_queue when it is no longer needed
257  * @kobj:    the kobj belonging of the request queue to be released
258  *
259  * Description:
260  *     blk_cleanup_queue is the pair to blk_init_queue() or
261  *     blk_queue_make_request().  It should be called when a request queue is
262  *     being released; typically when a block device is being de-registered.
263  *     Currently, its primary task it to free all the &struct request
264  *     structures that were allocated to the queue and the queue itself.
265  *
266  * Caveat:
267  *     Hopefully the low level driver will have finished any
268  *     outstanding requests first...
269  **/
270 static void blk_release_queue(struct kobject *kobj)
271 {
272 	struct request_queue *q =
273 		container_of(kobj, struct request_queue, kobj);
274 	struct request_list *rl = &q->rq;
275 
276 	blk_sync_queue(q);
277 
278 	if (rl->rq_pool)
279 		mempool_destroy(rl->rq_pool);
280 
281 	if (q->queue_tags)
282 		__blk_queue_free_tags(q);
283 
284 	blk_trace_shutdown(q);
285 
286 	bdi_destroy(&q->backing_dev_info);
287 	kmem_cache_free(blk_requestq_cachep, q);
288 }
289 
290 static struct sysfs_ops queue_sysfs_ops = {
291 	.show	= queue_attr_show,
292 	.store	= queue_attr_store,
293 };
294 
295 struct kobj_type blk_queue_ktype = {
296 	.sysfs_ops	= &queue_sysfs_ops,
297 	.default_attrs	= default_attrs,
298 	.release	= blk_release_queue,
299 };
300 
301 int blk_register_queue(struct gendisk *disk)
302 {
303 	int ret;
304 
305 	struct request_queue *q = disk->queue;
306 
307 	if (WARN_ON(!q))
308 		return -ENXIO;
309 
310 	if (!q->request_fn)
311 		return 0;
312 
313 	ret = kobject_add(&q->kobj, kobject_get(&disk->dev.kobj),
314 			  "%s", "queue");
315 	if (ret < 0)
316 		return ret;
317 
318 	kobject_uevent(&q->kobj, KOBJ_ADD);
319 
320 	ret = elv_register_queue(q);
321 	if (ret) {
322 		kobject_uevent(&q->kobj, KOBJ_REMOVE);
323 		kobject_del(&q->kobj);
324 		return ret;
325 	}
326 
327 	return 0;
328 }
329 
330 void blk_unregister_queue(struct gendisk *disk)
331 {
332 	struct request_queue *q = disk->queue;
333 
334 	if (WARN_ON(!q))
335 		return;
336 
337 	if (q->request_fn) {
338 		elv_unregister_queue(q);
339 
340 		kobject_uevent(&q->kobj, KOBJ_REMOVE);
341 		kobject_del(&q->kobj);
342 		kobject_put(&disk->dev.kobj);
343 	}
344 }
345