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authorTejun Heo <tj@kernel.org>2011-12-14 03:33:42 +0400
committerJens Axboe <axboe@kernel.dk>2011-12-14 03:33:42 +0400
commit7e5a8794492e43e9eebb68a98a23be055888ccd0 (patch)
treecc049a23b2c994f910d3101860bc1c2ecb7aa35f /include/linux/iocontext.h
parent3d3c2379feb177a5fd55bb0ed76776dc9d4f3243 (diff)
downloadlinux-7e5a8794492e43e9eebb68a98a23be055888ccd0.tar.xz
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/linux/iocontext.h')
-rw-r--r--include/linux/iocontext.h20
1 files changed, 14 insertions, 6 deletions
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 *);
};
/*