93 lines
2.0 KiB
C
93 lines
2.0 KiB
C
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#include <linux/wait.h>
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#include <linux/backing-dev.h>
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#include <linux/fs.h>
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#include <linux/sched.h>
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#include <linux/module.h>
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int bdi_init(struct backing_dev_info *bdi)
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{
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int i;
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int err;
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for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
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err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
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if (err)
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goto err;
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}
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bdi->dirty_exceeded = 0;
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err = prop_local_init_percpu(&bdi->completions);
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if (err) {
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err:
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while (i--)
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percpu_counter_destroy(&bdi->bdi_stat[i]);
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}
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return err;
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}
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EXPORT_SYMBOL(bdi_init);
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void bdi_destroy(struct backing_dev_info *bdi)
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{
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int i;
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for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
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percpu_counter_destroy(&bdi->bdi_stat[i]);
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prop_local_destroy_percpu(&bdi->completions);
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}
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EXPORT_SYMBOL(bdi_destroy);
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static wait_queue_head_t congestion_wqh[2] = {
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__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
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__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
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};
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void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
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{
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enum bdi_state bit;
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wait_queue_head_t *wqh = &congestion_wqh[rw];
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bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
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clear_bit(bit, &bdi->state);
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smp_mb__after_clear_bit();
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if (waitqueue_active(wqh))
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wake_up(wqh);
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}
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EXPORT_SYMBOL(clear_bdi_congested);
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void set_bdi_congested(struct backing_dev_info *bdi, int rw)
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{
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enum bdi_state bit;
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bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
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set_bit(bit, &bdi->state);
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}
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EXPORT_SYMBOL(set_bdi_congested);
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/**
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* congestion_wait - wait for a backing_dev to become uncongested
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* @rw: READ or WRITE
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* @timeout: timeout in jiffies
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*
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* Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
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* write congestion. If no backing_devs are congested then just wait for the
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* next write to be completed.
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*/
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long congestion_wait(int rw, long timeout)
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{
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long ret;
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DEFINE_WAIT(wait);
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wait_queue_head_t *wqh = &congestion_wqh[rw];
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prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
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ret = io_schedule_timeout(timeout);
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finish_wait(wqh, &wait);
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return ret;
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}
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EXPORT_SYMBOL(congestion_wait);
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