From b4924a0fa18d7f69bde3a84521258e7a55828186 Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Fri, 6 Mar 2015 20:23:44 +0800 Subject: [PATCH] Btrfs: catch transaction abortion after waiting for it 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 Signed-off-by: Chris Mason --- fs/btrfs/transaction.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 323c654..07b985f2 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -1811,6 +1811,9 @@ 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; -- 2.7.4