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Date: Sat, 29 Oct 2011 16:49:44 -0700
From: Tejun Heo <tj@...nel.org>
To: axboe@...nel.dk, vgoyal@...hat.com
Cc: ctalbott@...gle.com, rni@...gle.com, linux-kernel@...r.kernel.org,
Tejun Heo <tj@...nel.org>
Subject: [PATCH 07/10] 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: Tejun Heo <tj@...nel.org>
Cc: Jens Axboe <axboe@...nel.dk>
---
block/cfq-iosched.c | 48 ++++++++++++++-------------------------------
block/deadline-iosched.c | 4 +--
block/elevator.c | 37 +++++++++++++++++++++++++++++++++-
block/noop-iosched.c | 4 +--
include/linux/elevator.h | 11 +++++++++-
5 files changed, 62 insertions(+), 42 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 048fa69..06e59ab 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -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 -->
*/
@@ -4053,8 +4025,10 @@ 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_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);
diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index c644137..7bf12d7 100644
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -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)
diff --git a/block/elevator.c b/block/elevator.c
index c5c6214..cca049f 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -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);
diff --git a/block/noop-iosched.c b/block/noop-iosched.c
index 06389e9..413a0b1 100644
--- a/block/noop-iosched.c
+++ b/block/noop-iosched.c
@@ -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)
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 04958ef..d3d3e28 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -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 *);
/*
--
1.7.3.1
--
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