From 779adf0f647651f5a45eeee3442c881300ce989e Mon Sep 17 00:00:00 2001 From: David Sterba Date: Mon, 16 Feb 2015 19:39:00 +0100 Subject: [PATCH] btrfs: remove extra barrier before waitqueue_active Removing barriers is scary, but a call to atomic_dec_and_test implies a barrier, so we don't need to issue another one. Signed-off-by: David Sterba --- fs/btrfs/tree-log.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index d0deb4643502..63275594debd 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -229,7 +229,9 @@ int btrfs_pin_log_trans(struct btrfs_root *root) void btrfs_end_log_trans(struct btrfs_root *root) { if (atomic_dec_and_test(&root->log_writers)) { - smp_mb(); + /* + * Implicit memory barrier after atomic_dec_and_test + */ if (waitqueue_active(&root->log_writer_wait)) wake_up(&root->log_writer_wait); } @@ -2820,7 +2822,9 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans, mutex_lock(&log_root_tree->log_mutex); if (atomic_dec_and_test(&log_root_tree->log_writers)) { - smp_mb(); + /* + * Implicit memory barrier after atomic_dec_and_test + */ if (waitqueue_active(&log_root_tree->log_writer_wait)) wake_up(&log_root_tree->log_writer_wait); } -- 2.20.1