cfq-iosched: add hlist for browsing parallel to the radix tree
It's cumbersome to browse a radix tree from start to finish, especially
since we modify keys when a process exits. So add a hlist for the single
purpose of browsing over all known cfq_io_contexts, used for exit,
io prio change, etc.
This fixes http://bugzilla.kernel.org/show_bug.cgi?id=9948
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index 4ae0929..e34df7c 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -17,17 +17,13 @@
static void cfq_dtor(struct io_context *ioc)
{
- struct cfq_io_context *cic[1];
- int r;
+ if (!hlist_empty(&ioc->cic_list)) {
+ struct cfq_io_context *cic;
- /*
- * 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);
+ cic = list_entry(ioc->cic_list.first, struct cfq_io_context,
+ cic_list);
+ cic->dtor(ioc);
+ }
}
/*
@@ -57,18 +53,16 @@
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);
+ if (!hlist_empty(&ioc->cic_list)) {
+ struct cfq_io_context *cic;
+
+ cic = list_entry(ioc->cic_list.first, struct cfq_io_context,
+ cic_list);
+ cic->exit(ioc);
+ }
+ rcu_read_unlock();
}
/* Called by the exitting task */
@@ -105,6 +99,7 @@
ret->nr_batch_requests = 0; /* because this is 0 */
ret->aic = NULL;
INIT_RADIX_TREE(&ret->radix_root, GFP_ATOMIC | __GFP_HIGH);
+ INIT_HLIST_HEAD(&ret->cic_list);
ret->ioc_data = NULL;
}