This problem is uncovered by a test case: http://patchwork.ozlabs.org/patch/244297.
Fsync() can report success when it actually doesn't. When we have several threads running fsync() at the same tiem and in one fsync() we get a transaction abortion due to some problems(in the test case it's disk failures), and other fsync()s may return successfully which makes userspace programs think that data is now safely flushed into disk. It's because that after fsyncs() fail btrfs_sync_log() due to disk failures, they get to try btrfs_commit_transaction() where it finds that there is already a transaction being committed, and they'll just call wait_for_commit() and return. Note that we actually check "trans->aborted" in btrfs_end_transaction, but it's likely that the error message is still not yet throwed out and only after wait_for_commit() we're sure whether the transaction is committed successfully. This add the necessary check and it now passes the test. Signed-off-by: Liu Bo <bo.li....@oracle.com> --- v3: Remove the unnecessary macro ACCESS_ONCE() v2: Use a more generic title since it's not only for fsync, but for others. fs/btrfs/transaction.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 7e80f32..d28670c 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -1814,6 +1814,9 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, wait_for_commit(root, cur_trans); + if (unlikely(cur_trans->aborted)) + ret = cur_trans->aborted; + btrfs_put_transaction(cur_trans); return ret; -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html