Commit 6c71013e authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe

block: partition: convert percpu ref

Percpu refcount is the perfect match for partition's case,
and the conversion is quite straight.

With the convertion, one pair of atomic inc/dec can be saved
for accounting block I/O, which is run in hot path of block I/O.
Signed-off-by: default avatarMing Lei <tom.leiming@gmail.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent b54e5ed8
......@@ -1284,7 +1284,11 @@ struct gendisk *alloc_disk_node(int minors, int node_id)
* converted to make use of bd_mutex and sequence counters.
*/
seqcount_init(&disk->part0.nr_sects_seq);
hd_ref_init(&disk->part0);
if (hd_ref_init(&disk->part0)) {
hd_free_part(&disk->part0);
kfree(disk);
return NULL;
}
disk->minors = minors;
rand_initialize_disk(disk);
......
......@@ -232,8 +232,9 @@ static void delete_partition_rcu_cb(struct rcu_head *head)
put_device(part_to_dev(part));
}
void __delete_partition(struct hd_struct *part)
void __delete_partition(struct percpu_ref *ref)
{
struct hd_struct *part = container_of(ref, struct hd_struct, ref);
call_rcu(&part->rcu_head, delete_partition_rcu_cb);
}
......@@ -254,7 +255,7 @@ void delete_partition(struct gendisk *disk, int partno)
kobject_put(part->holder_dir);
device_del(part_to_dev(part));
hd_struct_put(part);
hd_struct_kill(part);
}
static ssize_t whole_disk_show(struct device *dev,
......@@ -355,8 +356,8 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno,
if (!dev_get_uevent_suppress(ddev))
kobject_uevent(&pdev->kobj, KOBJ_ADD);
hd_ref_init(p);
return p;
if (!hd_ref_init(p))
return p;
out_free_info:
free_part_info(p);
......
......@@ -13,6 +13,7 @@
#include <linux/kdev_t.h>
#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/percpu-refcount.h>
#ifdef CONFIG_BLOCK
......@@ -124,7 +125,7 @@ struct hd_struct {
#else
struct disk_stats dkstats;
#endif
atomic_t ref;
struct percpu_ref ref;
struct rcu_head rcu_head;
};
......@@ -611,7 +612,7 @@ extern struct hd_struct * __must_check add_partition(struct gendisk *disk,
sector_t len, int flags,
struct partition_meta_info
*info);
extern void __delete_partition(struct hd_struct *);
extern void __delete_partition(struct percpu_ref *);
extern void delete_partition(struct gendisk *, int);
extern void printk_all_partitions(void);
......@@ -640,33 +641,39 @@ extern ssize_t part_fail_store(struct device *dev,
const char *buf, size_t count);
#endif /* CONFIG_FAIL_MAKE_REQUEST */
static inline void hd_ref_init(struct hd_struct *part)
static inline int hd_ref_init(struct hd_struct *part)
{
atomic_set(&part->ref, 1);
smp_mb();
if (percpu_ref_init(&part->ref, __delete_partition, 0,
GFP_KERNEL))
return -ENOMEM;
return 0;
}
static inline void hd_struct_get(struct hd_struct *part)
{
atomic_inc(&part->ref);
smp_mb__after_atomic();
percpu_ref_get(&part->ref);
}
static inline int hd_struct_try_get(struct hd_struct *part)
{
return atomic_inc_not_zero(&part->ref);
return percpu_ref_tryget_live(&part->ref);
}
static inline void hd_struct_put(struct hd_struct *part)
{
if (atomic_dec_and_test(&part->ref))
__delete_partition(part);
percpu_ref_put(&part->ref);
}
static inline void hd_struct_kill(struct hd_struct *part)
{
percpu_ref_kill(&part->ref);
}
static inline void hd_free_part(struct hd_struct *part)
{
free_part_stats(part);
free_part_info(part);
percpu_ref_exit(&part->ref);
}
/*
......
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