This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / mm / backing-dev.c

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
new file mode 100644 (file)
index 0000000..f50a281
--- /dev/null
+++ b/mm/backing-dev.c
@@ -0,0 +1,69 @@
+
+#include <linux/wait.h>
+#include <linux/backing-dev.h>
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/module.h>
+
+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);
+
+/**
+ * congestion_end - wake up sleepers on a congested backing_dev_info
+ * @rw: READ or WRITE
+ */
+void congestion_end(int rw)
+{
+       wait_queue_head_t *wqh = &congestion_wqh[rw];
+
+       if (waitqueue_active(wqh))
+               wake_up(wqh);
+}
+EXPORT_SYMBOL(congestion_end);