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 }