From: Miao Xie <miaox@cn.fujitsu.com>
To: linux-btrfs@vger.kernel.org
Subject: [PATCH 5/9] Btrfs: remove unnecessary memory barrier in btrfs_sync_log()
Date: Thu, 20 Feb 2014 18:08:55 +0800 [thread overview]
Message-ID: <1392890939-19044-5-git-send-email-miaox@cn.fujitsu.com> (raw)
In-Reply-To: <1392890939-19044-1-git-send-email-miaox@cn.fujitsu.com>
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 --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);
/*
--
1.8.1.4
next prev parent reply other threads:[~2014-02-20 10:07 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-20 10:08 [PATCH 1/9] Btrfs: use ACCESS_ONCE to prevent the optimize accesses to ->last_trans_log_full_commit Miao Xie
2014-02-20 10:08 ` [PATCH 2/9] Btrfs: fix the skipped transaction commit during the file sync Miao Xie
2014-02-20 10:08 ` [PATCH 3/9] Btrfs: don't start the log transaction if the log tree init fails Miao Xie
2014-02-20 10:08 ` [PATCH 4/9] Btrfs: use bitfield instead of integer data type for the some variants in btrfs_root Miao Xie
2014-02-22 0:23 ` David Sterba
2014-02-26 9:10 ` Miao Xie
2014-02-27 17:02 ` David Sterba
2014-03-07 23:54 ` Josef Bacik
2014-03-08 0:00 ` Josef Bacik
2014-03-10 1:16 ` Miao Xie
2014-02-20 10:08 ` Miao Xie [this message]
2014-02-20 10:08 ` [PATCH 6/9] Btrfs: use signed integer instead of unsigned long integer for log transid Miao Xie
2014-02-20 10:08 ` [PATCH 7/9] Btrfs: stop joining the log transaction if sync log fails Miao Xie
2014-02-22 0:27 ` David Sterba
2014-02-26 8:51 ` Miao Xie
2014-02-20 10:08 ` [PATCH 8/9] Btrfs: fix skipped error handle when log sync failed Miao Xie
2014-02-20 10:08 ` [PATCH 9/9] Btrfs: just wait or commit our own log sub-transaction Miao Xie
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