From 7483e1a4464999c72b231af0efe39cb31fd73f14 Mon Sep 17 00:00:00 2001 From: Miao Xie Date: Thu, 20 Feb 2014 18:08:55 +0800 Subject: [PATCH] Btrfs: remove unnecessary memory barrier in btrfs_sync_log() Mutex unlock implies certain memory barriers to make sure all the memory operation completes before the unlock, and the next mutex lock implies memory barriers to make sure the all the memory happens after the lock. So it is a full memory barrier(smp_mb), we needn't add memory barriers. Remove them. Signed-off-by: Miao Xie Signed-off-by: Josef Bacik --- fs/btrfs/tree-log.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index ca960ad271fe..285c168391f3 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -2496,7 +2496,6 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans, root->log_transid++; log->log_transid = root->log_transid; root->log_start_pid = 0; - smp_mb(); /* * IO has been started, blocks of the log tree have WRITTEN flag set * in their headers. new modifications of the log will be written to @@ -2589,8 +2588,6 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans, btrfs_header_level(log_root_tree->node)); log_root_tree->log_transid++; - smp_mb(); - mutex_unlock(&log_root_tree->log_mutex); /*