From b004aa867c48b3232835b61ed9d44b572e29498e Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Sun, 22 Mar 2020 14:03:04 +0800 Subject: [PATCH] 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 Signed-off-by: Coly Li Signed-off-by: Jens Axboe --- drivers/md/bcache/writeback.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c index 6673a37..72ba6d0 100644 --- a/drivers/md/bcache/writeback.c +++ b/drivers/md/bcache/writeback.c @@ -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, -- 2.7.4