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bcache: optimize barrier usage for Rmw atomic bitops 

We can avoid the unnecessary barrier on non LL/SC architectures,
such as x86. Instead, use the smp_mb__after_atomic().

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Davidlohr Bueso 2020-03-22 14:03:04 +08:00 committed by Jens Axboe
parent 9876e38609
commit b004aa867c
1 changed files with 3 additions and 3 deletions
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6
drivers/md/bcache/writeback.c
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@ -183,7 +183,7 @@ static void update_writeback_rate(struct work_struct *work)
*/
set_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags);
/* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */
smp_mb();
smp_mb__after_atomic();
/*
* CACHE_SET_IO_DISABLE might be set via sysfs interface,
@ -193,7 +193,7 @@ static void update_writeback_rate(struct work_struct *work)
test_bit(CACHE_SET_IO_DISABLE, &c->flags)) {
clear_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags);
/* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */
smp_mb();
smp_mb__after_atomic();
return;
}
@ -229,7 +229,7 @@ static void update_writeback_rate(struct work_struct *work)
*/
clear_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags);
/* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */
smp_mb();
smp_mb__after_atomic();
}
static unsigned int writeback_delay(struct cached_dev *dc,