Merge branch 'blk-end-request' of git://git.kernel.dk/linux-2.6-block

[safe/jmp/linux-2.6] / block / ll_rw_blk.c

diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
index 4bf95b6..c16fdfe 100644 (file)
--- a/block/ll_rw_blk.c
+++ b/block/ll_rw_blk.c
@@ -3981,55 +3981,100 @@ int __init blk_dev_init(void)
        return 0;
 }
 
+static void cfq_dtor(struct io_context *ioc)
+{
+       struct cfq_io_context *cic[1];
+       int r;
+
+       /*
+        * We don't have a specific key to lookup with, so use the gang
+        * lookup to just retrieve the first item stored. The cfq exit
+        * function will iterate the full tree, so any member will do.
+        */
+       r = radix_tree_gang_lookup(&ioc->radix_root, (void **) cic, 0, 1);
+       if (r > 0)
+               cic[0]->dtor(ioc);
+}
+
 /*
- * IO Context helper functions
+ * IO Context helper functions. put_io_context() returns 1 if there are no
+ * more users of this io context, 0 otherwise.
  */
-void put_io_context(struct io_context *ioc)
+int put_io_context(struct io_context *ioc)
 {
        if (ioc == NULL)
-               return;
+               return 1;
 
        BUG_ON(atomic_read(&ioc->refcount) == 0);
 
        if (atomic_dec_and_test(&ioc->refcount)) {
-               struct cfq_io_context *cic;
-
                rcu_read_lock();
                if (ioc->aic && ioc->aic->dtor)
                        ioc->aic->dtor(ioc->aic);
-               if (ioc->cic_root.rb_node != NULL) {
-                       struct rb_node *n = rb_first(&ioc->cic_root);
-
-                       cic = rb_entry(n, struct cfq_io_context, rb_node);
-                       cic->dtor(ioc);
-               }
                rcu_read_unlock();
+               cfq_dtor(ioc);
 
                kmem_cache_free(iocontext_cachep, ioc);
+               return 1;
        }
+       return 0;
 }
 EXPORT_SYMBOL(put_io_context);
 
+static void cfq_exit(struct io_context *ioc)
+{
+       struct cfq_io_context *cic[1];
+       int r;
+
+       rcu_read_lock();
+       /*
+        * See comment for cfq_dtor()
+        */
+       r = radix_tree_gang_lookup(&ioc->radix_root, (void **) cic, 0, 1);
+       rcu_read_unlock();
+
+       if (r > 0)
+               cic[0]->exit(ioc);
+}
+
 /* Called by the exitting task */
 void exit_io_context(void)
 {
        struct io_context *ioc;
-       struct cfq_io_context *cic;
 
        task_lock(current);
        ioc = current->io_context;
        current->io_context = NULL;
        task_unlock(current);
 
-       ioc->task = NULL;
-       if (ioc->aic && ioc->aic->exit)
-               ioc->aic->exit(ioc->aic);
-       if (ioc->cic_root.rb_node != NULL) {
-               cic = rb_entry(rb_first(&ioc->cic_root), struct cfq_io_context, rb_node);
-               cic->exit(ioc);
+       if (atomic_dec_and_test(&ioc->nr_tasks)) {
+               if (ioc->aic && ioc->aic->exit)
+                       ioc->aic->exit(ioc->aic);
+               cfq_exit(ioc);
+
+               put_io_context(ioc);
        }
+}
+
+struct io_context *alloc_io_context(gfp_t gfp_flags, int node)
+{
+       struct io_context *ret;
 
-       put_io_context(ioc);
+       ret = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node);
+       if (ret) {
+               atomic_set(&ret->refcount, 1);
+               atomic_set(&ret->nr_tasks, 1);
+               spin_lock_init(&ret->lock);
+               ret->ioprio_changed = 0;
+               ret->ioprio = 0;
+               ret->last_waited = jiffies; /* doesn't matter... */
+               ret->nr_batch_requests = 0; /* because this is 0 */
+               ret->aic = NULL;
+               INIT_RADIX_TREE(&ret->radix_root, GFP_ATOMIC | __GFP_HIGH);
+               ret->ioc_data = NULL;
+       }
+
+       return ret;
 }
 
 /*
@@ -4049,16 +4094,8 @@ static struct io_context *current_io_context(gfp_t gfp_flags, int node)
        if (likely(ret))
                return ret;
 
-       ret = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node);
+       ret = alloc_io_context(gfp_flags, node);
        if (ret) {
-               atomic_set(&ret->refcount, 1);
-               ret->task = current;
-               ret->ioprio_changed = 0;
-               ret->last_waited = jiffies; /* doesn't matter... */
-               ret->nr_batch_requests = 0; /* because this is 0 */
-               ret->aic = NULL;
-               ret->cic_root.rb_node = NULL;
-               ret->ioc_data = NULL;
                /* make sure set_task_ioprio() sees the settings above */
                smp_wmb();
                tsk->io_context = ret;
@@ -4075,10 +4112,18 @@ static struct io_context *current_io_context(gfp_t gfp_flags, int node)
  */
 struct io_context *get_io_context(gfp_t gfp_flags, int node)
 {
-       struct io_context *ret;
-       ret = current_io_context(gfp_flags, node);
-       if (likely(ret))
-               atomic_inc(&ret->refcount);
+       struct io_context *ret = NULL;
+
+       /*
+        * Check for unlikely race with exiting task. ioc ref count is
+        * zero when ioc is being detached.
+        */
+       do {
+               ret = current_io_context(gfp_flags, node);
+               if (unlikely(!ret))
+                       break;
+       } while (!atomic_inc_not_zero(&ret->refcount));
+
        return ret;
 }
 EXPORT_SYMBOL(get_io_context);