linux/block/blk-sysfs.c
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   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
  12struct 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
  18static ssize_t
  19queue_var_show(unsigned int var, char *page)
  20{
  21        return sprintf(page, "%d\n", var);
  22}
  23
  24static ssize_t
  25queue_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
  33static ssize_t queue_requests_show(struct request_queue *q, char *page)
  34{
  35        return queue_var_show(q->nr_requests, (page));
  36}
  37
  38static ssize_t
  39queue_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
  78static 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
  85static ssize_t
  86queue_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
  98static 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
 105static 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
 110static ssize_t
 111queue_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
 131static 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
 138static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
 139{
 140        return queue_var_show(blk_queue_nomerges(q), page);
 141}
 142
 143static 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
 159static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page)
 160{
 161        unsigned int set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);
 162
 163        return queue_var_show(set != 0, page);
 164}
 165
 166static ssize_t
 167queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
 168{
 169        ssize_t ret = -EINVAL;
 170#if defined(CONFIG_USE_GENERIC_SMP_HELPERS)
 171        unsigned long val;
 172
 173        ret = queue_var_store(&val, page, count);
 174        spin_lock_irq(q->queue_lock);
 175        if (val)
 176                queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
 177        else
 178                queue_flag_clear(QUEUE_FLAG_SAME_COMP,  q);
 179        spin_unlock_irq(q->queue_lock);
 180#endif
 181        return ret;
 182}
 183
 184static struct queue_sysfs_entry queue_requests_entry = {
 185        .attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
 186        .show = queue_requests_show,
 187        .store = queue_requests_store,
 188};
 189
 190static struct queue_sysfs_entry queue_ra_entry = {
 191        .attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
 192        .show = queue_ra_show,
 193        .store = queue_ra_store,
 194};
 195
 196static struct queue_sysfs_entry queue_max_sectors_entry = {
 197        .attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
 198        .show = queue_max_sectors_show,
 199        .store = queue_max_sectors_store,
 200};
 201
 202static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
 203        .attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
 204        .show = queue_max_hw_sectors_show,
 205};
 206
 207static struct queue_sysfs_entry queue_iosched_entry = {
 208        .attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
 209        .show = elv_iosched_show,
 210        .store = elv_iosched_store,
 211};
 212
 213static struct queue_sysfs_entry queue_hw_sector_size_entry = {
 214        .attr = {.name = "hw_sector_size", .mode = S_IRUGO },
 215        .show = queue_hw_sector_size_show,
 216};
 217
 218static struct queue_sysfs_entry queue_nomerges_entry = {
 219        .attr = {.name = "nomerges", .mode = S_IRUGO | S_IWUSR },
 220        .show = queue_nomerges_show,
 221        .store = queue_nomerges_store,
 222};
 223
 224static struct queue_sysfs_entry queue_rq_affinity_entry = {
 225        .attr = {.name = "rq_affinity", .mode = S_IRUGO | S_IWUSR },
 226        .show = queue_rq_affinity_show,
 227        .store = queue_rq_affinity_store,
 228};
 229
 230static struct attribute *default_attrs[] = {
 231        &queue_requests_entry.attr,
 232        &queue_ra_entry.attr,
 233        &queue_max_hw_sectors_entry.attr,
 234        &queue_max_sectors_entry.attr,
 235        &queue_iosched_entry.attr,
 236        &queue_hw_sector_size_entry.attr,
 237        &queue_nomerges_entry.attr,
 238        &queue_rq_affinity_entry.attr,
 239        NULL,
 240};
 241
 242#define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
 243
 244static ssize_t
 245queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
 246{
 247        struct queue_sysfs_entry *entry = to_queue(attr);
 248        struct request_queue *q =
 249                container_of(kobj, struct request_queue, kobj);
 250        ssize_t res;
 251
 252        if (!entry->show)
 253                return -EIO;
 254        mutex_lock(&q->sysfs_lock);
 255        if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
 256                mutex_unlock(&q->sysfs_lock);
 257                return -ENOENT;
 258        }
 259        res = entry->show(q, page);
 260        mutex_unlock(&q->sysfs_lock);
 261        return res;
 262}
 263
 264static ssize_t
 265queue_attr_store(struct kobject *kobj, struct attribute *attr,
 266                    const char *page, size_t length)
 267{
 268        struct queue_sysfs_entry *entry = to_queue(attr);
 269        struct request_queue *q;
 270        ssize_t res;
 271
 272        if (!entry->store)
 273                return -EIO;
 274
 275        q = container_of(kobj, struct request_queue, kobj);
 276        mutex_lock(&q->sysfs_lock);
 277        if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
 278                mutex_unlock(&q->sysfs_lock);
 279                return -ENOENT;
 280        }
 281        res = entry->store(q, page, length);
 282        mutex_unlock(&q->sysfs_lock);
 283        return res;
 284}
 285
 286/**
 287 * blk_cleanup_queue: - release a &struct request_queue when it is no longer needed
 288 * @kobj:    the kobj belonging of the request queue to be released
 289 *
 290 * Description:
 291 *     blk_cleanup_queue is the pair to blk_init_queue() or
 292 *     blk_queue_make_request().  It should be called when a request queue is
 293 *     being released; typically when a block device is being de-registered.
 294 *     Currently, its primary task it to free all the &struct request
 295 *     structures that were allocated to the queue and the queue itself.
 296 *
 297 * Caveat:
 298 *     Hopefully the low level driver will have finished any
 299 *     outstanding requests first...
 300 **/
 301static void blk_release_queue(struct kobject *kobj)
 302{
 303        struct request_queue *q =
 304                container_of(kobj, struct request_queue, kobj);
 305        struct request_list *rl = &q->rq;
 306
 307        blk_sync_queue(q);
 308
 309        if (rl->rq_pool)
 310                mempool_destroy(rl->rq_pool);
 311
 312        if (q->queue_tags)
 313                __blk_queue_free_tags(q);
 314
 315        blk_trace_shutdown(q);
 316
 317        bdi_destroy(&q->backing_dev_info);
 318        kmem_cache_free(blk_requestq_cachep, q);
 319}
 320
 321static struct sysfs_ops queue_sysfs_ops = {
 322        .show   = queue_attr_show,
 323        .store  = queue_attr_store,
 324};
 325
 326struct kobj_type blk_queue_ktype = {
 327        .sysfs_ops      = &queue_sysfs_ops,
 328        .default_attrs  = default_attrs,
 329        .release        = blk_release_queue,
 330};
 331
 332int blk_register_queue(struct gendisk *disk)
 333{
 334        int ret;
 335
 336        struct request_queue *q = disk->queue;
 337
 338        if (WARN_ON(!q))
 339                return -ENXIO;
 340
 341        if (!q->request_fn)
 342                return 0;
 343
 344        ret = kobject_add(&q->kobj, kobject_get(&disk_to_dev(disk)->kobj),
 345                          "%s", "queue");
 346        if (ret < 0)
 347                return ret;
 348
 349        kobject_uevent(&q->kobj, KOBJ_ADD);
 350
 351        ret = elv_register_queue(q);
 352        if (ret) {
 353                kobject_uevent(&q->kobj, KOBJ_REMOVE);
 354                kobject_del(&q->kobj);
 355                return ret;
 356        }
 357
 358        return 0;
 359}
 360
 361void blk_unregister_queue(struct gendisk *disk)
 362{
 363        struct request_queue *q = disk->queue;
 364
 365        if (WARN_ON(!q))
 366                return;
 367
 368        if (q->request_fn) {
 369                elv_unregister_queue(q);
 370
 371                kobject_uevent(&q->kobj, KOBJ_REMOVE);
 372                kobject_del(&q->kobj);
 373                kobject_put(&disk_to_dev(disk)->kobj);
 374        }
 375}
 376
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