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
 139 static struct queue_sysfs_entry queue_requests_entry = {
 140         .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
 141         .show = queue_requests_show,
 142         .store = queue_requests_store,
 143 };
 144
 145 static struct queue_sysfs_entry queue_ra_entry = {
 146         .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
 147         .show = queue_ra_show,
 148         .store = queue_ra_store,
 149 };
 150
 151 static struct queue_sysfs_entry queue_max_sectors_entry = {
 152         .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
 153         .show = queue_max_sectors_show,
 154         .store = queue_max_sectors_store,
 155 };
 156
 157 static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
 158         .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
 159         .show = queue_max_hw_sectors_show,
 160 };
 161
 162 static struct queue_sysfs_entry queue_iosched_entry = {
 163         .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
 164         .show = elv_iosched_show,
 165         .store = elv_iosched_store,
 166 };
 167
 168 static struct queue_sysfs_entry queue_hw_sector_size_entry = {
 169         .attr = {.name = "hw_sector_size", .mode = S_IRUGO },
 170         .show = queue_hw_sector_size_show,
 171 };
 172
 173 static struct attribute *default_attrs[] = {
 174         &queue_requests_entry.attr,
 175         &queue_ra_entry.attr,
 176         &queue_max_hw_sectors_entry.attr,
 177         &queue_max_sectors_entry.attr,
 178         &queue_iosched_entry.attr,
 179         &queue_hw_sector_size_entry.attr,
 180         NULL,
 181 };
 182
 183 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
 184
 185 static ssize_t
 186 queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 187 {
 188         struct queue_sysfs_entry *entry = to_queue(attr);
 189         struct request_queue *q =
 190                 container_of(kobj, struct request_queue, kobj);
 191         ssize_t res;
 192
 193         if (!entry->show)
 194                 return -EIO;
 195         mutex_lock(&q->sysfs_lock);
 196         if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
 197                 mutex_unlock(&q->sysfs_lock);
 198                 return -ENOENT;
 199         }
 200         res = entry->show(q, page);
 201         mutex_unlock(&q->sysfs_lock);
 202         return res;
 203 }
 204
 205 static ssize_t
 206 queue_attr_store(struct kobject *kobj, struct attribute *attr,
 207                     const char *page, size_t length)
 208 {
 209         struct queue_sysfs_entry *entry = to_queue(attr);
 210         struct request_queue *q;
 211         ssize_t res;
 212
 213         if (!entry->store)
 214                 return -EIO;
 215
 216         q = container_of(kobj, struct request_queue, kobj);
 217         mutex_lock(&q->sysfs_lock);
 218         if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
 219                 mutex_unlock(&q->sysfs_lock);
 220                 return -ENOENT;
 221         }
 222         res = entry->store(q, page, length);
 223         mutex_unlock(&q->sysfs_lock);
 224         return res;
 225 }
 226
 227 /**
 228  * blk_cleanup_queue: - release a &struct request_queue when it is no longer needed
 229  * @kobj:    the kobj belonging of the request queue to be released
 230  *
 231  * Description:
 232  *     blk_cleanup_queue is the pair to blk_init_queue() or
 233  *     blk_queue_make_request().  It should be called when a request queue is
 234  *     being released; typically when a block device is being de-registered.
 235  *     Currently, its primary task it to free all the &struct request
 236  *     structures that were allocated to the queue and the queue itself.
 237  *
 238  * Caveat:
 239  *     Hopefully the low level driver will have finished any
 240  *     outstanding requests first...
 241  **/
 242 static void blk_release_queue(struct kobject *kobj)
 243 {
 244         struct request_queue *q =
 245                 container_of(kobj, struct request_queue, kobj);
 246         struct request_list *rl = &q->rq;
 247
 248         blk_sync_queue(q);
 249
 250         if (rl->rq_pool)
 251                 mempool_destroy(rl->rq_pool);
 252
 253         if (q->queue_tags)
 254                 __blk_queue_free_tags(q);
 255
 256         blk_trace_shutdown(q);
 257
 258         bdi_destroy(&q->backing_dev_info);
 259         kmem_cache_free(blk_requestq_cachep, q);
 260 }
 261
 262 static struct sysfs_ops queue_sysfs_ops = {
 263         .show   = queue_attr_show,
 264         .store  = queue_attr_store,
 265 };
 266
 267 struct kobj_type blk_queue_ktype = {
 268         .sysfs_ops      = &queue_sysfs_ops,
 269         .default_attrs  = default_attrs,
 270         .release        = blk_release_queue,
 271 };
 272
 273 int blk_register_queue(struct gendisk *disk)
 274 {
 275         int ret;
 276
 277         struct request_queue *q = disk->queue;
 278
 279         if (!q || !q->request_fn)
 280                 return -ENXIO;
 281
 282         ret = kobject_add(&q->kobj, kobject_get(&disk->dev.kobj),
 283                           "%s", "queue");
 284         if (ret < 0)
 285                 return ret;
 286
 287         kobject_uevent(&q->kobj, KOBJ_ADD);
 288
 289         ret = elv_register_queue(q);
 290         if (ret) {
 291                 kobject_uevent(&q->kobj, KOBJ_REMOVE);
 292                 kobject_del(&q->kobj);
 293                 return ret;
 294         }
 295
 296         return 0;
 297 }
 298
 299 void blk_unregister_queue(struct gendisk *disk)
 300 {
 301         struct request_queue *q = disk->queue;
 302
 303         if (q && q->request_fn) {
 304                 elv_unregister_queue(q);
 305
 306                 kobject_uevent(&q->kobj, KOBJ_REMOVE);
 307                 kobject_del(&q->kobj);
 308                 kobject_put(&disk->dev.kobj);
 309         }
 310 }