From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([222.73.24.84]:41967 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753834Ab3AOG0n (ORCPT ); Tue, 15 Jan 2013 01:26:43 -0500 Message-ID: <50F4F6CD.8070402@cn.fujitsu.com> Date: Tue, 15 Jan 2013 14:27:25 +0800 From: Miao Xie Reply-To: miaox@cn.fujitsu.com MIME-Version: 1.0 To: Linux Btrfs CC: dsterba@suse.cz Subject: [PATCH V2 11/11] Btrfs: Add ACCESS_ONCE() to transaction->abort accesses References: <50EEB9AF.2010301@cn.fujitsu.com> <20130110173800.GH20089@twin.jikos.cz> In-Reply-To: <20130110173800.GH20089@twin.jikos.cz> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-btrfs-owner@vger.kernel.org List-ID: We may access and update transaction->aborted on the different CPUs without lock, so we need ACCESS_ONCE() wrapper to prevent the compiler from creating unsolicited accesses and make sure we can get the right value. Signed-off-by: Miao Xie --- Changelog v1 -> v2: - modify the changelog - split the old patch into two patches, this is the first one - just add ACCESS_ONCE() wrapper. --- fs/btrfs/super.c | 2 +- fs/btrfs/transaction.c | 3 ++- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index f714379..0d88513 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -267,7 +267,7 @@ void __btrfs_abort_transaction(struct btrfs_trans_handle *trans, function, line, errstr); return; } - trans->transaction->aborted = errno; + ACCESS_ONCE(trans->transaction->aborted) = errno; __btrfs_std_error(root->fs_info, function, line, errno, NULL); } /* diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index a950d48..7dbfe2c 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -1468,7 +1468,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, goto cleanup_transaction; } - if (cur_trans->aborted) { + /* Stop the commit early if ->aborted is set */ + if (unlikely(ACCESS_ONCE(cur_trans->aborted))) { ret = cur_trans->aborted; goto cleanup_transaction; } -- 1.7.11.7