Re: [dm-devel] [PATCH 30/44] block: move disk stat accounting to struct block_device

[Jan Kara <jack@suse.cz>]

On Thu 26-11-20 14:04:08, Christoph Hellwig wrote:
> Move the dkstats and stamp field to struct block_device in preparation
> of killing struct hd_struct.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks good. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  block/blk-cgroup.c        |  2 +-
>  block/blk-core.c          |  4 ++--
>  block/blk.h               |  1 -
>  block/genhd.c             | 14 ++++----------
>  block/partitions/core.c   |  9 +--------
>  fs/block_dev.c            | 10 ++++++++++
>  include/linux/blk_types.h |  2 ++
>  include/linux/genhd.h     |  2 --
>  include/linux/part_stat.h | 38 +++++++++++++++++++-------------------
>  9 files changed, 39 insertions(+), 43 deletions(-)
> 
> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
> index 19650eb42b9f00..5c0a9d588e6312 100644
> --- a/block/blk-cgroup.c
> +++ b/block/blk-cgroup.c
> @@ -830,7 +830,7 @@ static void blkcg_fill_root_iostats(void)
>  		for_each_possible_cpu(cpu) {
>  			struct disk_stats *cpu_dkstats;
>  
> -			cpu_dkstats = per_cpu_ptr(part->dkstats, cpu);
> +			cpu_dkstats = per_cpu_ptr(part->bdev->bd_stats, cpu);
>  			tmp.ios[BLKG_IOSTAT_READ] +=
>  				cpu_dkstats->ios[STAT_READ];
>  			tmp.ios[BLKG_IOSTAT_WRITE] +=
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 988f45094a387b..d2c9cb24e087f3 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -1264,9 +1264,9 @@ static void update_io_ticks(struct hd_struct *part, unsigned long now, bool end)
>  {
>  	unsigned long stamp;
>  again:
> -	stamp = READ_ONCE(part->stamp);
> +	stamp = READ_ONCE(part->bdev->bd_stamp);
>  	if (unlikely(stamp != now)) {
> -		if (likely(cmpxchg(&part->stamp, stamp, now) == stamp))
> +		if (likely(cmpxchg(&part->bdev->bd_stamp, stamp, now) == stamp))
>  			__part_stat_add(part, io_ticks, end ? now - stamp : 1);
>  	}
>  	if (part->partno) {
> diff --git a/block/blk.h b/block/blk.h
> index 09cee7024fb43e..3f801f6e86f8a1 100644
> --- a/block/blk.h
> +++ b/block/blk.h
> @@ -381,7 +381,6 @@ static inline void hd_struct_put(struct hd_struct *part)
>  
>  static inline void hd_free_part(struct hd_struct *part)
>  {
> -	free_percpu(part->dkstats);
>  	kfree(part->info);
>  	bdput(part->bdev);
>  	percpu_ref_exit(&part->ref);
> diff --git a/block/genhd.c b/block/genhd.c
> index c6016fde4725b0..9eead2970cb3d4 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -104,7 +104,7 @@ static void part_stat_read_all(struct hd_struct *part, struct disk_stats *stat)
>  
>  	memset(stat, 0, sizeof(struct disk_stats));
>  	for_each_possible_cpu(cpu) {
> -		struct disk_stats *ptr = per_cpu_ptr(part->dkstats, cpu);
> +		struct disk_stats *ptr = per_cpu_ptr(part->bdev->bd_stats, cpu);
>  		int group;
>  
>  		for (group = 0; group < NR_STAT_GROUPS; group++) {
> @@ -883,7 +883,7 @@ void del_gendisk(struct gendisk *disk)
>  	kobject_put(disk->slave_dir);
>  
>  	part_stat_set_all(&disk->part0, 0);
> -	disk->part0.stamp = 0;
> +	disk->part0.bdev->bd_stamp = 0;
>  	if (!sysfs_deprecated)
>  		sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
>  	pm_runtime_set_memalloc_noio(disk_to_dev(disk), false);
> @@ -1620,19 +1620,15 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
>  	if (!disk->part0.bdev)
>  		goto out_free_disk;
>  
> -	disk->part0.dkstats = alloc_percpu(struct disk_stats);
> -	if (!disk->part0.dkstats)
> -		goto out_bdput;
> -
>  	disk->node_id = node_id;
>  	if (disk_expand_part_tbl(disk, 0))
> -		goto out_free_bdstats;
> +		goto out_bdput;
>  
>  	ptbl = rcu_dereference_protected(disk->part_tbl, 1);
>  	rcu_assign_pointer(ptbl->part[0], &disk->part0);
>  
>  	if (hd_ref_init(&disk->part0))
> -		goto out_free_bdstats;
> +		goto out_bdput;
>  
>  	disk->minors = minors;
>  	rand_initialize_disk(disk);
> @@ -1641,8 +1637,6 @@ struct gendisk *__alloc_disk_node(int minors, int node_id)
>  	device_initialize(disk_to_dev(disk));
>  	return disk;
>  
> -out_free_bdstats:
> -	free_percpu(disk->part0.dkstats);
>  out_bdput:
>  	bdput(disk->part0.bdev);
>  out_free_disk:
> diff --git a/block/partitions/core.c b/block/partitions/core.c
> index bcfa8215bd5ef3..8924e1ea8b2ad6 100644
> --- a/block/partitions/core.c
> +++ b/block/partitions/core.c
> @@ -409,14 +409,9 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno,
>  	if (!p)
>  		return ERR_PTR(-EBUSY);
>  
> -	err = -ENOMEM;
> -	p->dkstats = alloc_percpu(struct disk_stats);
> -	if (!p->dkstats)
> -		goto out_free;
> -
>  	bdev = bdev_alloc(disk, partno);
>  	if (!bdev)
> -		goto out_free_stats;
> +		goto out_free;
>  	p->bdev = bdev;
>  
>  	pdev = part_to_dev(p);
> @@ -490,8 +485,6 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno,
>  	kfree(p->info);
>  out_bdput:
>  	bdput(bdev);
> -out_free_stats:
> -	free_percpu(p->dkstats);
>  out_free:
>  	kfree(p);
>  	return ERR_PTR(err);
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index b6ebfb7754d3b7..11e6a9a255845d 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -32,6 +32,7 @@
>  #include <linux/cleancache.h>
>  #include <linux/task_io_accounting_ops.h>
>  #include <linux/falloc.h>
> +#include <linux/part_stat.h>
>  #include <linux/uaccess.h>
>  #include <linux/suspend.h>
>  #include "internal.h"
> @@ -781,6 +782,10 @@ static struct inode *bdev_alloc_inode(struct super_block *sb)
>  
>  static void bdev_free_inode(struct inode *inode)
>  {
> +	struct block_device *bdev = I_BDEV(inode);
> +
> +	free_percpu(bdev->bd_stats);
> +
>  	kmem_cache_free(bdev_cachep, BDEV_I(inode));
>  }
>  
> @@ -875,6 +880,11 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
>  #ifdef CONFIG_SYSFS
>  	INIT_LIST_HEAD(&bdev->bd_holder_disks);
>  #endif
> +	bdev->bd_stats = alloc_percpu(struct disk_stats);
> +	if (!bdev->bd_stats) {
> +		iput(inode);
> +		return NULL;
> +	}
>  	return bdev;
>  }
>  
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index 2e0a9bd9688d28..520011b95276fb 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -20,6 +20,8 @@ typedef void (bio_end_io_t) (struct bio *);
>  struct bio_crypt_ctx;
>  
>  struct block_device {
> +	struct disk_stats __percpu *bd_stats;
> +	unsigned long		bd_stamp;
>  	dev_t			bd_dev;
>  	int			bd_openers;
>  	struct inode *		bd_inode;	/* will die */
> diff --git a/include/linux/genhd.h b/include/linux/genhd.h
> index 30d4785b7df8bb..804ac45fbfbc53 100644
> --- a/include/linux/genhd.h
> +++ b/include/linux/genhd.h
> @@ -52,8 +52,6 @@ struct partition_meta_info {
>  
>  struct hd_struct {
>  	sector_t start_sect;
> -	unsigned long stamp;
> -	struct disk_stats __percpu *dkstats;
>  	struct percpu_ref ref;
>  
>  	struct block_device *bdev;
> diff --git a/include/linux/part_stat.h b/include/linux/part_stat.h
> index 24125778ef3ec7..87ad60106e1db0 100644
> --- a/include/linux/part_stat.h
> +++ b/include/linux/part_stat.h
> @@ -25,17 +25,17 @@ struct disk_stats {
>  #define part_stat_unlock()	preempt_enable()
>  
>  #define part_stat_get_cpu(part, field, cpu)				\
> -	(per_cpu_ptr((part)->dkstats, (cpu))->field)
> +	(per_cpu_ptr((part)->bdev->bd_stats, (cpu))->field)
>  
>  #define part_stat_get(part, field)					\
>  	part_stat_get_cpu(part, field, smp_processor_id())
>  
>  #define part_stat_read(part, field)					\
>  ({									\
> -	typeof((part)->dkstats->field) res = 0;				\
> +	typeof((part)->bdev->bd_stats->field) res = 0;			\
>  	unsigned int _cpu;						\
>  	for_each_possible_cpu(_cpu)					\
> -		res += per_cpu_ptr((part)->dkstats, _cpu)->field;	\
> +		res += per_cpu_ptr((part)->bdev->bd_stats, _cpu)->field; \
>  	res;								\
>  })
>  
> @@ -44,7 +44,7 @@ static inline void part_stat_set_all(struct hd_struct *part, int value)
>  	int i;
>  
>  	for_each_possible_cpu(i)
> -		memset(per_cpu_ptr(part->dkstats, i), value,
> +		memset(per_cpu_ptr(part->bdev->bd_stats, i), value,
>  				sizeof(struct disk_stats));
>  }
>  
> @@ -54,7 +54,7 @@ static inline void part_stat_set_all(struct hd_struct *part, int value)
>  	 part_stat_read(part, field[STAT_DISCARD]))
>  
>  #define __part_stat_add(part, field, addnd)				\
> -	__this_cpu_add((part)->dkstats->field, addnd)
> +	__this_cpu_add((part)->bdev->bd_stats->field, addnd)
>  
>  #define part_stat_add(part, field, addnd)	do {			\
>  	__part_stat_add((part), field, addnd);				\
> @@ -63,20 +63,20 @@ static inline void part_stat_set_all(struct hd_struct *part, int value)
>  				field, addnd);				\
>  } while (0)
>  
> -#define part_stat_dec(gendiskp, field)					\
> -	part_stat_add(gendiskp, field, -1)
> -#define part_stat_inc(gendiskp, field)					\
> -	part_stat_add(gendiskp, field, 1)
> -#define part_stat_sub(gendiskp, field, subnd)				\
> -	part_stat_add(gendiskp, field, -subnd)
> +#define part_stat_dec(part, field)					\
> +	part_stat_add(part, field, -1)
> +#define part_stat_inc(part, field)					\
> +	part_stat_add(part, field, 1)
> +#define part_stat_sub(part, field, subnd)				\
> +	part_stat_add(part, field, -subnd)
>  
> -#define part_stat_local_dec(gendiskp, field)				\
> -	local_dec(&(part_stat_get(gendiskp, field)))
> -#define part_stat_local_inc(gendiskp, field)				\
> -	local_inc(&(part_stat_get(gendiskp, field)))
> -#define part_stat_local_read(gendiskp, field)				\
> -	local_read(&(part_stat_get(gendiskp, field)))
> -#define part_stat_local_read_cpu(gendiskp, field, cpu)			\
> -	local_read(&(part_stat_get_cpu(gendiskp, field, cpu)))
> +#define part_stat_local_dec(part, field)				\
> +	local_dec(&(part_stat_get(part, field)))
> +#define part_stat_local_inc(part, field)				\
> +	local_inc(&(part_stat_get(part, field)))
> +#define part_stat_local_read(part, field)				\
> +	local_read(&(part_stat_get(part, field)))
> +#define part_stat_local_read_cpu(part, field, cpu)			\
> +	local_read(&(part_stat_get_cpu(part, field, cpu)))
>  
>  #endif /* _LINUX_PART_STAT_H */
> -- 
> 2.29.2
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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