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linux-sg2042
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block: always use a percpu variable for disk stats 

percpu variables have a perfectly fine working stub implementation
for UP kernels, so use that.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2020-05-27 07:24:14 +02:00 committed by Jens Axboe
parent 9123bf6f21
commit 58d4f14fc3
5 changed files with 18 additions and 69 deletions
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2
block/blk.h
View File

@ -378,7 +378,7 @@ static inline void hd_struct_put(struct hd_struct *part)
static inline void hd_free_part(struct hd_struct *part)
{
free_part_stats(part);
free_percpu(part->dkstats);
kfree(part->info);
percpu_ref_exit(&part->ref);
}

12
block/genhd.c
View File

@ -92,7 +92,6 @@ const char *bdevname(struct block_device *bdev, char *buf)
}
EXPORT_SYMBOL(bdevname);
#ifdef CONFIG_SMP
static void part_stat_read_all(struct hd_struct *part, struct disk_stats *stat)
{
int cpu;
@ -112,12 +111,6 @@ static void part_stat_read_all(struct hd_struct *part, struct disk_stats *stat)
stat->io_ticks += ptr->io_ticks;
}
}
#else /* CONFIG_SMP */
static void part_stat_read_all(struct hd_struct *part, struct disk_stats *stat)
{
memcpy(stat, &part->dkstats, sizeof(struct disk_stats));
}
#endif /* CONFIG_SMP */
static unsigned int part_in_flight(struct request_queue *q,
struct hd_struct *part)
@ -1688,14 +1681,15 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
disk = kzalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id);
if (disk) {
if (!init_part_stats(&disk->part0)) {
disk->part0.dkstats = alloc_percpu(struct disk_stats);
if (!disk->part0.dkstats) {
kfree(disk);
return NULL;
}
init_rwsem(&disk->lookup_sem);
disk->node_id = node_id;
if (disk_expand_part_tbl(disk, 0)) {
free_part_stats(&disk->part0);
free_percpu(disk->part0.dkstats);
kfree(disk);
return NULL;
}

5
block/partitions/core.c
View File

@ -387,7 +387,8 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno,
if (!p)
return ERR_PTR(-EBUSY);
if (!init_part_stats(p)) {
p->dkstats = alloc_percpu(struct disk_stats);
if (!p->dkstats) {
err = -ENOMEM;
goto out_free;
}
@ -468,7 +469,7 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno,
out_free_info:
kfree(p->info);
out_free_stats:
free_part_stats(p);
free_percpu(p->dkstats);
out_free:
kfree(p);
return ERR_PTR(err);

13
include/linux/genhd.h
View File

@ -39,15 +39,6 @@ extern struct class block_class;
#include <linux/fs.h>
#include <linux/workqueue.h>
struct disk_stats {
u64 nsecs[NR_STAT_GROUPS];
unsigned long sectors[NR_STAT_GROUPS];
unsigned long ios[NR_STAT_GROUPS];
unsigned long merges[NR_STAT_GROUPS];
unsigned long io_ticks;
local_t in_flight[2];
};
#define PARTITION_META_INFO_VOLNAMELTH 64
/*
* Enough for the string representation of any kind of UUID plus NULL.
@ -72,11 +63,7 @@ struct hd_struct {
seqcount_t nr_sects_seq;
#endif
unsigned long stamp;
#ifdef CONFIG_SMP
struct disk_stats __percpu *dkstats;
#else
struct disk_stats dkstats;
#endif
struct percpu_ref ref;
sector_t alignment_offset;

55
include/linux/part_stat.h
View File

@ -4,19 +4,23 @@
#include <linux/genhd.h>
struct disk_stats {
u64 nsecs[NR_STAT_GROUPS];
unsigned long sectors[NR_STAT_GROUPS];
unsigned long ios[NR_STAT_GROUPS];
unsigned long merges[NR_STAT_GROUPS];
unsigned long io_ticks;
local_t in_flight[2];
};
/*
* Macros to operate on percpu disk statistics:
*
* {disk|part|all}_stat_{add|sub|inc|dec}() modify the stat counters
* and should be called between disk_stat_lock() and
* disk_stat_unlock().
* {disk|part|all}_stat_{add|sub|inc|dec}() modify the stat counters and should
* be called between disk_stat_lock() and disk_stat_unlock().
*
* part_stat_read() can be called at any time.
*
* part_stat_{add|set_all}() and {init|free}_part_stats are for
* internal use only.
*/
#ifdef CONFIG_SMP
#define part_stat_lock() ({ rcu_read_lock(); get_cpu(); })
#define part_stat_unlock() do { put_cpu(); rcu_read_unlock(); } while (0)
@ -44,43 +48,6 @@ static inline void part_stat_set_all(struct hd_struct *part, int value)
sizeof(struct disk_stats));
}
static inline int init_part_stats(struct hd_struct *part)
{
part->dkstats = alloc_percpu(struct disk_stats);
if (!part->dkstats)
return 0;
return 1;
}
static inline void free_part_stats(struct hd_struct *part)
{
free_percpu(part->dkstats);
}
#else /* !CONFIG_SMP */
#define part_stat_lock() ({ rcu_read_lock(); 0; })
#define part_stat_unlock() rcu_read_unlock()
#define part_stat_get(part, field) ((part)->dkstats.field)
#define part_stat_get_cpu(part, field, cpu) part_stat_get(part, field)
#define part_stat_read(part, field) part_stat_get(part, field)
static inline void part_stat_set_all(struct hd_struct *part, int value)
{
memset(&part->dkstats, value, sizeof(struct disk_stats));
}
static inline int init_part_stats(struct hd_struct *part)
{
return 1;
}
static inline void free_part_stats(struct hd_struct *part)
{
}
#endif /* CONFIG_SMP */
#define part_stat_read_accum(part, field) \
(part_stat_read(part, field[STAT_READ]) + \
part_stat_read(part, field[STAT_WRITE]) + \