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block: remove rcu_read_lock() from part_stat_lock()

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The RCU lock is required only in disk_map_sector_rcu() to lookup the
partition.  After that request holds reference to related hd_struct.

Replace get_cpu() with preempt_disable() - returned cpu index is unused.

[hch: rebased]

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Konstantin Khlebnikov 2020-05-27 07:24:17 +02:00 • committed by Jens Axboe
parent b5af37ab3a
commit 8ab1d40a64
2 changed files with 10 additions and 5 deletions
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4
include/linux/part_stat.h
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@ -21,8 +21,8 @@ struct disk_stats {
*
* part_stat_read() can be called at any time.
*/
#define part_stat_lock() ({ rcu_read_lock(); get_cpu(); })
#define part_stat_unlock() do { put_cpu(); rcu_read_unlock(); } while (0)
#define part_stat_lock() preempt_disable()
#define part_stat_unlock() preempt_enable()
#define part_stat_get_cpu(part, field, cpu) \
(per_cpu_ptr((part)->dkstats, (cpu))->field)