[safe/jmp/linux-2.6] / mm / backing-dev.c

#include <linux/wait.h>
#include <linux/backing-dev.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/writeback.h>
#include <linux/device.h>


static struct class *bdi_class;

static ssize_t read_ahead_kb_store(struct device *dev,
                                  struct device_attribute *attr,
                                  const char *buf, size_t count)
{
        struct backing_dev_info *bdi = dev_get_drvdata(dev);
        char *end;
        unsigned long read_ahead_kb;
        ssize_t ret = -EINVAL;

        read_ahead_kb = simple_strtoul(buf, &end, 10);
        if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
                bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
                ret = count;
        }
        return ret;
}

#define K(pages) ((pages) << (PAGE_SHIFT - 10))

#define BDI_SHOW(name, expr)                                            \
static ssize_t name##_show(struct device *dev,                          \
                           struct device_attribute *attr, char *page)   \
{                                                                       \
        struct backing_dev_info *bdi = dev_get_drvdata(dev);            \
                                                                        \
        return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr);  \
}

BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))

BDI_SHOW(reclaimable_kb, K(bdi_stat(bdi, BDI_RECLAIMABLE)))
BDI_SHOW(writeback_kb, K(bdi_stat(bdi, BDI_WRITEBACK)))

static inline unsigned long get_dirty(struct backing_dev_info *bdi, int i)
{
        unsigned long thresh[3];

        get_dirty_limits(&thresh[0], &thresh[1], &thresh[2], bdi);

        return thresh[i];
}

BDI_SHOW(dirty_kb, K(get_dirty(bdi, 1)))
BDI_SHOW(bdi_dirty_kb, K(get_dirty(bdi, 2)))

#define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store)

static struct device_attribute bdi_dev_attrs[] = {
        __ATTR_RW(read_ahead_kb),
        __ATTR_RO(reclaimable_kb),
        __ATTR_RO(writeback_kb),
        __ATTR_RO(dirty_kb),
        __ATTR_RO(bdi_dirty_kb),
        __ATTR_NULL,
};

static __init int bdi_class_init(void)
{
        bdi_class = class_create(THIS_MODULE, "bdi");
        bdi_class->dev_attrs = bdi_dev_attrs;
        return 0;
}

core_initcall(bdi_class_init);

int bdi_register(struct backing_dev_info *bdi, struct device *parent,
                const char *fmt, ...)
{
        char *name;
        va_list args;
        int ret = 0;
        struct device *dev;

        va_start(args, fmt);
        name = kvasprintf(GFP_KERNEL, fmt, args);
        va_end(args);

        if (!name)
                return -ENOMEM;

        dev = device_create(bdi_class, parent, MKDEV(0, 0), name);
        if (IS_ERR(dev)) {
                ret = PTR_ERR(dev);
                goto exit;
        }

        bdi->dev = dev;
        dev_set_drvdata(bdi->dev, bdi);

exit:
        kfree(name);
        return ret;
}
EXPORT_SYMBOL(bdi_register);

int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
{
        return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
}
EXPORT_SYMBOL(bdi_register_dev);

void bdi_unregister(struct backing_dev_info *bdi)
{
        if (bdi->dev) {
                device_unregister(bdi->dev);
                bdi->dev = NULL;
        }
}
EXPORT_SYMBOL(bdi_unregister);

int bdi_init(struct backing_dev_info *bdi)
{
        int i;
        int err;

        bdi->dev = NULL;

        for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
                err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
                if (err)
                        goto err;
        }

        bdi->dirty_exceeded = 0;
        err = prop_local_init_percpu(&bdi->completions);

        if (err) {
err:
                while (i--)
                        percpu_counter_destroy(&bdi->bdi_stat[i]);
        }

        return err;
}
EXPORT_SYMBOL(bdi_init);

void bdi_destroy(struct backing_dev_info *bdi)
{
        int i;

        bdi_unregister(bdi);

        for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
                percpu_counter_destroy(&bdi->bdi_stat[i]);

        prop_local_destroy_percpu(&bdi->completions);
}
EXPORT_SYMBOL(bdi_destroy);

static wait_queue_head_t congestion_wqh[2] = {
                __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
                __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
        };


void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
{
        enum bdi_state bit;
        wait_queue_head_t *wqh = &congestion_wqh[rw];

        bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
        clear_bit(bit, &bdi->state);
        smp_mb__after_clear_bit();
        if (waitqueue_active(wqh))
                wake_up(wqh);
}
EXPORT_SYMBOL(clear_bdi_congested);

void set_bdi_congested(struct backing_dev_info *bdi, int rw)
{
        enum bdi_state bit;

        bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
        set_bit(bit, &bdi->state);
}
EXPORT_SYMBOL(set_bdi_congested);

/**
 * congestion_wait - wait for a backing_dev to become uncongested
 * @rw: READ or WRITE
 * @timeout: timeout in jiffies
 *
 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
 * write congestion.  If no backing_devs are congested then just wait for the
 * next write to be completed.
 */
long congestion_wait(int rw, long timeout)
{
        long ret;
        DEFINE_WAIT(wait);
        wait_queue_head_t *wqh = &congestion_wqh[rw];

        prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
        ret = io_schedule_timeout(timeout);
        finish_wait(wqh, &wait);
        return ret;
}
EXPORT_SYMBOL(congestion_wait);