Btrfs: Add ACCESS_ONCE() to transaction->abort accesses

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 <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

2 files changed, 3 insertions, 2 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 99545df1b86c..d8982e9601d3 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 87fac9a21ea5..0ef29611fade 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;
         }