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[5/9] Btrfs: remove unnecessary memory barrier in btrfs_sync_log()

Message ID 1392890939-19044-5-git-send-email-miaox@cn.fujitsu.com (mailing list archive)
State Accepted, archived
Headers show

Commit Message

Miao Xie Feb. 20, 2014, 10:08 a.m. UTC 
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 <miaox@cn.fujitsu.com>
---
 fs/btrfs/tree-log.c | 3 ---
 1 file changed, 3 deletions(-)
diff mbox

Patch

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 51d1bd9..c9f2479 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2497,7 +2497,6 @@  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
@@ -2590,8 +2589,6 @@  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);
 
 	/*