linux/block/blk-sysfs.c
Akinobu Mita fb19974630 block: fix blk_register_queue() return value
blk_register_queue() returns -ENXIO when queue->request_fn is NULL.  But there
are some block drivers that call blk_register_queue() via add_disk() with
queue->request_fn == NULL.  (For example, brd, loop)

Although no one checks return value of blk_register_queue(), this patch makes
it return 0 instead of -ENXIO when queue->request_fn is NULL,

Also this patch adds warning when blk_register_queue() and
blk_unregister_queue() are called with queue == NULL rather than ignore
invalid usage silently.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-04-21 09:51:06 +02:00

316 lines
7.7 KiB
C

/*
* Functions related to sysfs handling
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/blktrace_api.h>
#include "blk.h"
struct queue_sysfs_entry {
struct attribute attr;
ssize_t (*show)(struct request_queue *, char *);
ssize_t (*store)(struct request_queue *, const char *, size_t);
};
static ssize_t
queue_var_show(unsigned int var, char *page)
{
return sprintf(page, "%d\n", var);
}
static ssize_t
queue_var_store(unsigned long *var, const char *page, size_t count)
{
char *p = (char *) page;
*var = simple_strtoul(p, &p, 10);
return count;
}
static ssize_t queue_requests_show(struct request_queue *q, char *page)
{
return queue_var_show(q->nr_requests, (page));
}
static ssize_t
queue_requests_store(struct request_queue *q, const char *page, size_t count)
{
struct request_list *rl = &q->rq;
unsigned long nr;
int ret = queue_var_store(&nr, page, count);
if (nr < BLKDEV_MIN_RQ)
nr = BLKDEV_MIN_RQ;
spin_lock_irq(q->queue_lock);
q->nr_requests = nr;
blk_queue_congestion_threshold(q);
if (rl->count[READ] >= queue_congestion_on_threshold(q))
blk_set_queue_congested(q, READ);
else if (rl->count[READ] < queue_congestion_off_threshold(q))
blk_clear_queue_congested(q, READ);
if (rl->count[WRITE] >= queue_congestion_on_threshold(q))
blk_set_queue_congested(q, WRITE);
else if (rl->count[WRITE] < queue_congestion_off_threshold(q))
blk_clear_queue_congested(q, WRITE);
if (rl->count[READ] >= q->nr_requests) {
blk_set_queue_full(q, READ);
} else if (rl->count[READ]+1 <= q->nr_requests) {
blk_clear_queue_full(q, READ);
wake_up(&rl->wait[READ]);
}
if (rl->count[WRITE] >= q->nr_requests) {
blk_set_queue_full(q, WRITE);
} else if (rl->count[WRITE]+1 <= q->nr_requests) {
blk_clear_queue_full(q, WRITE);
wake_up(&rl->wait[WRITE]);
}
spin_unlock_irq(q->queue_lock);
return ret;
}
static ssize_t queue_ra_show(struct request_queue *q, char *page)
{
int ra_kb = q->backing_dev_info.ra_pages << (PAGE_CACHE_SHIFT - 10);
return queue_var_show(ra_kb, (page));
}
static ssize_t
queue_ra_store(struct request_queue *q, const char *page, size_t count)
{
unsigned long ra_kb;
ssize_t ret = queue_var_store(&ra_kb, page, count);
spin_lock_irq(q->queue_lock);
q->backing_dev_info.ra_pages = ra_kb >> (PAGE_CACHE_SHIFT - 10);
spin_unlock_irq(q->queue_lock);
return ret;
}
static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
{
int max_sectors_kb = q->max_sectors >> 1;
return queue_var_show(max_sectors_kb, (page));
}
static ssize_t queue_hw_sector_size_show(struct request_queue *q, char *page)
{
return queue_var_show(q->hardsect_size, page);
}
static ssize_t
queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
{
unsigned long max_sectors_kb,
max_hw_sectors_kb = q->max_hw_sectors >> 1,
page_kb = 1 << (PAGE_CACHE_SHIFT - 10);
ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
return -EINVAL;
/*
* Take the queue lock to update the readahead and max_sectors
* values synchronously:
*/
spin_lock_irq(q->queue_lock);
q->max_sectors = max_sectors_kb << 1;
spin_unlock_irq(q->queue_lock);
return ret;
}
static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
{
int max_hw_sectors_kb = q->max_hw_sectors >> 1;
return queue_var_show(max_hw_sectors_kb, (page));
}
static struct queue_sysfs_entry queue_requests_entry = {
.attr = {.name = "nr_requests", .mode = S_IRUGO | S_IWUSR },
.show = queue_requests_show,
.store = queue_requests_store,
};
static struct queue_sysfs_entry queue_ra_entry = {
.attr = {.name = "read_ahead_kb", .mode = S_IRUGO | S_IWUSR },
.show = queue_ra_show,
.store = queue_ra_store,
};
static struct queue_sysfs_entry queue_max_sectors_entry = {
.attr = {.name = "max_sectors_kb", .mode = S_IRUGO | S_IWUSR },
.show = queue_max_sectors_show,
.store = queue_max_sectors_store,
};
static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
.attr = {.name = "max_hw_sectors_kb", .mode = S_IRUGO },
.show = queue_max_hw_sectors_show,
};
static struct queue_sysfs_entry queue_iosched_entry = {
.attr = {.name = "scheduler", .mode = S_IRUGO | S_IWUSR },
.show = elv_iosched_show,
.store = elv_iosched_store,
};
static struct queue_sysfs_entry queue_hw_sector_size_entry = {
.attr = {.name = "hw_sector_size", .mode = S_IRUGO },
.show = queue_hw_sector_size_show,
};
static struct attribute *default_attrs[] = {
&queue_requests_entry.attr,
&queue_ra_entry.attr,
&queue_max_hw_sectors_entry.attr,
&queue_max_sectors_entry.attr,
&queue_iosched_entry.attr,
&queue_hw_sector_size_entry.attr,
NULL,
};
#define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
static ssize_t
queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
{
struct queue_sysfs_entry *entry = to_queue(attr);
struct request_queue *q =
container_of(kobj, struct request_queue, kobj);
ssize_t res;
if (!entry->show)
return -EIO;
mutex_lock(&q->sysfs_lock);
if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
mutex_unlock(&q->sysfs_lock);
return -ENOENT;
}
res = entry->show(q, page);
mutex_unlock(&q->sysfs_lock);
return res;
}
static ssize_t
queue_attr_store(struct kobject *kobj, struct attribute *attr,
const char *page, size_t length)
{
struct queue_sysfs_entry *entry = to_queue(attr);
struct request_queue *q;
ssize_t res;
if (!entry->store)
return -EIO;
q = container_of(kobj, struct request_queue, kobj);
mutex_lock(&q->sysfs_lock);
if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags)) {
mutex_unlock(&q->sysfs_lock);
return -ENOENT;
}
res = entry->store(q, page, length);
mutex_unlock(&q->sysfs_lock);
return res;
}
/**
* blk_cleanup_queue: - release a &struct request_queue when it is no longer needed
* @kobj: the kobj belonging of the request queue to be released
*
* Description:
* blk_cleanup_queue is the pair to blk_init_queue() or
* blk_queue_make_request(). It should be called when a request queue is
* being released; typically when a block device is being de-registered.
* Currently, its primary task it to free all the &struct request
* structures that were allocated to the queue and the queue itself.
*
* Caveat:
* Hopefully the low level driver will have finished any
* outstanding requests first...
**/
static void blk_release_queue(struct kobject *kobj)
{
struct request_queue *q =
container_of(kobj, struct request_queue, kobj);
struct request_list *rl = &q->rq;
blk_sync_queue(q);
if (rl->rq_pool)
mempool_destroy(rl->rq_pool);
if (q->queue_tags)
__blk_queue_free_tags(q);
blk_trace_shutdown(q);
bdi_destroy(&q->backing_dev_info);
kmem_cache_free(blk_requestq_cachep, q);
}
static struct sysfs_ops queue_sysfs_ops = {
.show = queue_attr_show,
.store = queue_attr_store,
};
struct kobj_type blk_queue_ktype = {
.sysfs_ops = &queue_sysfs_ops,
.default_attrs = default_attrs,
.release = blk_release_queue,
};
int blk_register_queue(struct gendisk *disk)
{
int ret;
struct request_queue *q = disk->queue;
if (WARN_ON(!q))
return -ENXIO;
if (!q->request_fn)
return 0;
ret = kobject_add(&q->kobj, kobject_get(&disk->dev.kobj),
"%s", "queue");
if (ret < 0)
return ret;
kobject_uevent(&q->kobj, KOBJ_ADD);
ret = elv_register_queue(q);
if (ret) {
kobject_uevent(&q->kobj, KOBJ_REMOVE);
kobject_del(&q->kobj);
return ret;
}
return 0;
}
void blk_unregister_queue(struct gendisk *disk)
{
struct request_queue *q = disk->queue;
if (WARN_ON(!q))
return;
if (q->request_fn) {
elv_unregister_queue(q);
kobject_uevent(&q->kobj, KOBJ_REMOVE);
kobject_del(&q->kobj);
kobject_put(&disk->dev.kobj);
}
}