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Commit 3d3c2379 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
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block, cfq: move icq cache management to block core 



Let elevators set ->icq_size and ->icq_align in elevator_type and
elv_register() and elv_unregister() respectively create and destroy
kmem_cache for icq.

* elv_register() now can return failure.  All callers updated.

* icq caches are automatically named "ELVNAME_io_cq".

* cfq_slab_setup/kill() are collapsed into cfq_init/exit().

* While at it, minor indentation change for iosched_cfq.elevator_name
  for consistency.

This will help moving icq management to block core.  This doesn't
introduce any functional change.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 47fdd4ca

block/cfq-iosched.c

+15 −33
Original line number Diff line number Diff line
@@ -3914,34 +3914,6 @@ static void *cfq_init_queue(struct request_queue *q) 
	return cfqd;

}



static void cfq_slab_kill(void)

{

	/*

	 * Caller already ensured that pending RCU callbacks are completed,

	 * so we should have no busy allocations at this point.

	 */

	if (cfq_pool)

		kmem_cache_destroy(cfq_pool);

	if (cfq_icq_pool)

		kmem_cache_destroy(cfq_icq_pool);

}



static int __init cfq_slab_setup(void)

{

	cfq_pool = KMEM_CACHE(cfq_queue, 0);

	if (!cfq_pool)

		goto fail;



	cfq_icq_pool = KMEM_CACHE(cfq_io_cq, 0);

	if (!cfq_icq_pool)

		goto fail;



	return 0;

fail:

	cfq_slab_kill();

	return -ENOMEM;

}



/*

 * sysfs parts below -->

 */
@@ -4053,6 +4025,8 @@ static struct elevator_type iosched_cfq = { 
		.elevator_init_fn =		cfq_init_queue,

		.elevator_exit_fn =		cfq_exit_queue,

	},

	.icq_size	=	sizeof(struct cfq_io_cq),

	.icq_align	=	__alignof__(struct cfq_io_cq),

	.elevator_attrs =	cfq_attrs,

	.elevator_name	=	"cfq",

	.elevator_owner =	THIS_MODULE,
@@ -4072,6 +4046,8 @@ static struct blkio_policy_type blkio_policy_cfq; 


static int __init cfq_init(void)

{

	int ret;



	/*

	 * could be 0 on HZ < 1000 setups

	 */
@@ -4086,10 +4062,17 @@ static int __init cfq_init(void) 
#else

		cfq_group_idle = 0;

#endif

	if (cfq_slab_setup())

	cfq_pool = KMEM_CACHE(cfq_queue, 0);

	if (!cfq_pool)

		return -ENOMEM;



	elv_register(&iosched_cfq);

	ret = elv_register(&iosched_cfq);

	if (ret) {

		kmem_cache_destroy(cfq_pool);

		return ret;

	}

	cfq_icq_pool = iosched_cfq.icq_cache;



	blkio_policy_register(&blkio_policy_cfq);



	return 0;
@@ -4099,8 +4082,7 @@ static void __exit cfq_exit(void) 
{

	blkio_policy_unregister(&blkio_policy_cfq);

	elv_unregister(&iosched_cfq);

	rcu_barrier();	/* make sure all cic RCU frees are complete */

	cfq_slab_kill();

	kmem_cache_destroy(cfq_pool);

}



module_init(cfq_init);

block/deadline-iosched.c

+1 −3
Original line number Diff line number Diff line
@@ -448,9 +448,7 @@ static struct elevator_type iosched_deadline = { 


static int __init deadline_init(void)

{

	elv_register(&iosched_deadline);



	return 0;

	return elv_register(&iosched_deadline);

}



static void __exit deadline_exit(void)

block/elevator.c

+35 −2
Original line number Diff line number Diff line
@@ -886,15 +886,36 @@ void elv_unregister_queue(struct request_queue *q) 
}

EXPORT_SYMBOL(elv_unregister_queue);



void elv_register(struct elevator_type *e)

int elv_register(struct elevator_type *e)

{

	char *def = "";



	/* create icq_cache if requested */

	if (e->icq_size) {

		if (WARN_ON(e->icq_size < sizeof(struct io_cq)) ||

		    WARN_ON(e->icq_align < __alignof__(struct io_cq)))

			return -EINVAL;



		snprintf(e->icq_cache_name, sizeof(e->icq_cache_name),

			 "%s_io_cq", e->elevator_name);

		e->icq_cache = kmem_cache_create(e->icq_cache_name, e->icq_size,

						 e->icq_align, 0, NULL);

		if (!e->icq_cache)

			return -ENOMEM;

	}



	/* register, don't allow duplicate names */

	spin_lock(&elv_list_lock);

	BUG_ON(elevator_find(e->elevator_name));

	if (elevator_find(e->elevator_name)) {

		spin_unlock(&elv_list_lock);

		if (e->icq_cache)

			kmem_cache_destroy(e->icq_cache);

		return -EBUSY;

	}

	list_add_tail(&e->list, &elv_list);

	spin_unlock(&elv_list_lock);



	/* print pretty message */

	if (!strcmp(e->elevator_name, chosen_elevator) ||

			(!*chosen_elevator &&

			 !strcmp(e->elevator_name, CONFIG_DEFAULT_IOSCHED)))
@@ -902,14 +923,26 @@ void elv_register(struct elevator_type *e) 


	printk(KERN_INFO "io scheduler %s registered%s\n", e->elevator_name,

								def);

	return 0;

}

EXPORT_SYMBOL_GPL(elv_register);



void elv_unregister(struct elevator_type *e)

{

	/* unregister */

	spin_lock(&elv_list_lock);

	list_del_init(&e->list);

	spin_unlock(&elv_list_lock);



	/*

	 * Destroy icq_cache if it exists.  icq's are RCU managed.  Make

	 * sure all RCU operations are complete before proceeding.

	 */

	if (e->icq_cache) {

		rcu_barrier();

		kmem_cache_destroy(e->icq_cache);

		e->icq_cache = NULL;

	}

}

EXPORT_SYMBOL_GPL(elv_unregister);

block/noop-iosched.c

+1 −3
Original line number Diff line number Diff line
@@ -94,9 +94,7 @@ static struct elevator_type elevator_noop = { 


static int __init noop_init(void)

{

	elv_register(&elevator_noop);



	return 0;

	return elv_register(&elevator_noop);

}



static void __exit noop_exit(void)

include/linux/elevator.h

+10 −1
Original line number Diff line number Diff line
@@ -78,10 +78,19 @@ struct elv_fs_entry { 
 */

struct elevator_type

{

	/* managed by elevator core */

	struct kmem_cache *icq_cache;



	/* fields provided by elevator implementation */

	struct elevator_ops ops;

	size_t icq_size;

	size_t icq_align;

	struct elv_fs_entry *elevator_attrs;

	char elevator_name[ELV_NAME_MAX];

	struct module *elevator_owner;



	/* managed by elevator core */

	char icq_cache_name[ELV_NAME_MAX + 5];	/* elvname + "_io_cq" */

	struct list_head list;

};
@@ -127,7 +136,7 @@ extern void elv_drain_elevator(struct request_queue *); 
/*

 * io scheduler registration

 */

extern void elv_register(struct elevator_type *);

extern int elv_register(struct elevator_type *);

extern void elv_unregister(struct elevator_type *);



/*