From: Wang Shilong Date: Wed, 19 Feb 2014 11:24:19 +0000 (+0800) Subject: Btrfs: wake up @scrub_pause_wait as much as we can X-Git-Tag: firefly_0821_release~176^2~3883^2~92 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=32a447896c7b4c5cf5502a3ca7f5ef57d498fb03;p=firefly-linux-kernel-4.4.55.git Btrfs: wake up @scrub_pause_wait as much as we can check if @scrubs_running=@scrubs_paused condition inside wait_event() is not an atomic operation which means we may inc/dec @scrub_running/ paused at any time. Let's wake up @scrub_pause_wait as much as we can to let commit transaction blocked less. An example below: Thread1 Thread2 |->scrub_blocked_if_needed() |->scrub_pending_trans_workers_inc |->increase @scrub_paused |->increase @scrub_running |->wake up scrub_pause_wait list |->scrub blocked |->increase @scrub_paused Thread3 is commiting transaction which is blocked at btrfs_scrub_pause(). So after Thread2 increase @scrub_paused, we meet the condition @scrub_paused=@scrub_running, but transaction will be still blocked until another calling to wake up @scrub_pause_wait. Signed-off-by: Wang Shilong Signed-off-by: Miao Xie Signed-off-by: Josef Bacik --- diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index f2f8803ea79c..682ec3fca4a1 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -315,6 +315,16 @@ static void scrub_pending_trans_workers_inc(struct scrub_ctx *sctx) atomic_inc(&fs_info->scrubs_running); atomic_inc(&fs_info->scrubs_paused); mutex_unlock(&fs_info->scrub_lock); + + /* + * check if @scrubs_running=@scrubs_paused condition + * inside wait_event() is not an atomic operation. + * which means we may inc/dec @scrub_running/paused + * at any time. Let's wake up @scrub_pause_wait as + * much as we can to let commit transaction blocked less. + */ + wake_up(&fs_info->scrub_pause_wait); + atomic_inc(&sctx->workers_pending); }