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authorTejun Heo <tj@kernel.org>2011-12-14 00:33:42 +0100
committerJens Axboe <axboe@kernel.dk>2011-12-14 00:33:42 +0100
commit7e5a8794492e43e9eebb68a98a23be055888ccd0 (patch)
treecc049a23b2c994f910d3101860bc1c2ecb7aa35f /include
parent3d3c2379feb177a5fd55bb0ed76776dc9d4f3243 (diff)
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block, cfq: move io_cq exit/release to blk-ioc.c
With kmem_cache managed by blk-ioc, io_cq exit/release can be moved to blk-ioc too. The odd ->io_cq->exit/release() callbacks are replaced with elevator_ops->elevator_exit_icq_fn() with unlinking from both ioc and q, and freeing automatically handled by blk-ioc. The elevator operation only need to perform exit operation specific to the elevator - in cfq's case, exiting the cfqq's. Also, clearing of io_cq's on q detach is moved to block core and automatically performed on elevator switch and q release. Because the q io_cq points to might be freed before RCU callback for the io_cq runs, blk-ioc code should remember to which cache the io_cq needs to be freed when the io_cq is released. New field io_cq->__rcu_icq_cache is added for this purpose. As both the new field and rcu_head are used only after io_cq is released and the q/ioc_node fields aren't, they are put into unions. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include')
-rw-r--r--include/linux/elevator.h5
-rw-r--r--include/linux/iocontext.h20
2 files changed, 19 insertions, 6 deletions
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index d3d3e28cbfd4..06e4dd568717 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -5,6 +5,8 @@
#ifdef CONFIG_BLOCK
+struct io_cq;
+
typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
struct bio *);
@@ -24,6 +26,7 @@ typedef struct request *(elevator_request_list_fn) (struct request_queue *, stru
typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
typedef int (elevator_may_queue_fn) (struct request_queue *, int);
+typedef void (elevator_exit_icq_fn) (struct io_cq *);
typedef int (elevator_set_req_fn) (struct request_queue *, struct request *, gfp_t);
typedef void (elevator_put_req_fn) (struct request *);
typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
@@ -56,6 +59,8 @@ struct elevator_ops
elevator_request_list_fn *elevator_former_req_fn;
elevator_request_list_fn *elevator_latter_req_fn;
+ elevator_exit_icq_fn *elevator_exit_icq_fn;
+
elevator_set_req_fn *elevator_set_req_fn;
elevator_put_req_fn *elevator_put_req_fn;
diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h
index d15ca6591f96..ac390a34c0e7 100644
--- a/include/linux/iocontext.h
+++ b/include/linux/iocontext.h
@@ -14,14 +14,22 @@ struct io_cq {
struct request_queue *q;
struct io_context *ioc;
- struct list_head q_node;
- struct hlist_node ioc_node;
+ /*
+ * q_node and ioc_node link io_cq through icq_list of q and ioc
+ * respectively. Both fields are unused once ioc_exit_icq() is
+ * called and shared with __rcu_icq_cache and __rcu_head which are
+ * used for RCU free of io_cq.
+ */
+ union {
+ struct list_head q_node;
+ struct kmem_cache *__rcu_icq_cache;
+ };
+ union {
+ struct hlist_node ioc_node;
+ struct rcu_head __rcu_head;
+ };
unsigned long changed;
- struct rcu_head rcu_head;
-
- void (*exit)(struct io_cq *);
- void (*release)(struct io_cq *);
};
/*