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block: RCU free request_queue

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RCU free request_queue so that blkcg_gq->q can be dereferenced under
RCU lock.  This will be used to implement hierarchical stats.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
This commit is contained in:
Tejun Heo 2013-01-09 08:05:13 -08:00
parent 16b3de6652
commit 548bc8e1b3
2 changed files with 10 additions and 1 deletions
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9
block/blk-sysfs.c
View File

@ -497,6 +497,13 @@ queue_attr_store(struct kobject *kobj, struct attribute *attr,
return res; return res;
} }
static void blk_free_queue_rcu(struct rcu_head *rcu_head)
{
struct request_queue *q = container_of(rcu_head, struct request_queue,
rcu_head);
kmem_cache_free(blk_requestq_cachep, q);
}
/** /**
* blk_release_queue: - release a &struct request_queue when it is no longer needed * blk_release_queue: - release a &struct request_queue when it is no longer needed
* @kobj: the kobj belonging to the request queue to be released * @kobj: the kobj belonging to the request queue to be released
@ -538,7 +545,7 @@ static void blk_release_queue(struct kobject *kobj)
bdi_destroy(&q->backing_dev_info); bdi_destroy(&q->backing_dev_info);
ida_simple_remove(&blk_queue_ida, q->id); ida_simple_remove(&blk_queue_ida, q->id);
kmem_cache_free(blk_requestq_cachep, q); call_rcu(&q->rcu_head, blk_free_queue_rcu);
} }
static const struct sysfs_ops queue_sysfs_ops = { static const struct sysfs_ops queue_sysfs_ops = {

2
include/linux/blkdev.h
View File

@ -19,6 +19,7 @@
#include <linux/gfp.h> #include <linux/gfp.h>
#include <linux/bsg.h> #include <linux/bsg.h>
#include <linux/smp.h> #include <linux/smp.h>
#include <linux/rcupdate.h>
#include <asm/scatterlist.h> #include <asm/scatterlist.h>
@ -437,6 +438,7 @@ struct request_queue {
/* Throttle data */ /* Throttle data */
struct throtl_data *td; struct throtl_data *td;
#endif #endif
struct rcu_head rcu_head;
}; };
#define QUEUE_FLAG_QUEUED 1 /* uses generic tag queueing */ #define QUEUE_FLAG_QUEUED 1 /* uses generic tag queueing */