block: initial patch for on-stack per-task plugging

[linux-2.6-block.git] / kernel / sched.c

diff --git a/kernel/sched.c b/kernel/sched.c
index 18d38e4ec7ba249ba46079beab5a773700a7eb3b..ca098bf4cc65b78791a296d2c9400cf919f2a502 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3978,6 +3978,16 @@ need_resched_nonpreemptible:
                switch_count = &prev->nvcsw;
        }
 
+       /*
+        * If we are going to sleep and we have plugged IO queued, make
+        * sure to submit it to avoid deadlocks.
+        */
+       if (prev->state != TASK_RUNNING && blk_needs_flush_plug(prev)) {
+               raw_spin_unlock(&rq->lock);
+               blk_flush_plug(prev);
+               raw_spin_lock(&rq->lock);
+       }
+
        pre_schedule(rq, prev);
 
        if (unlikely(!rq->nr_running))
@@ -5333,6 +5343,7 @@ void __sched io_schedule(void)
 
        delayacct_blkio_start();
        atomic_inc(&rq->nr_iowait);
+       blk_flush_plug(current);
        current->in_iowait = 1;
        schedule();
        current->in_iowait = 0;
@@ -5348,6 +5359,7 @@ long __sched io_schedule_timeout(long timeout)
 
        delayacct_blkio_start();
        atomic_inc(&rq->nr_iowait);
+       blk_flush_plug(current);
        current->in_iowait = 1;
        ret = schedule_timeout(timeout);
        current->in_iowait = 0;