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>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
index 593b222d9dcc..1b4ccf25b4d2 100644
--- a/include/linux/iocontext.h
+++ b/include/linux/iocontext.h
@@ -50,6 +50,7 @@ struct cfq_io_context {
 	sector_t seek_mean;
 
 	struct list_head queue_list;
+	struct hlist_node cic_list;
 
 	void (*dtor)(struct io_context *); /* destructor */
 	void (*exit)(struct io_context *); /* called on task exit */
@@ -77,6 +78,7 @@ struct io_context {
 
 	struct as_io_context *aic;
 	struct radix_tree_root radix_root;
+	struct hlist_head cic_list;
 	void *ioc_data;
 };