Return-Path: Received: from szxga05-in.huawei.com ([45.249.212.191]:2242 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1733118AbfAPNey (ORCPT ); Wed, 16 Jan 2019 08:34:54 -0500 From: "zhangyi (F)" To: CC: , , , , Subject: [PATCH v2] jbd2: make sure dirty flag is cleared while revorking a buffer which belongs to older transaction Date: Wed, 16 Jan 2019 21:38:23 +0800 Message-ID: <1547645903-57295-1-git-send-email-yi.zhang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-ext4-owner@vger.kernel.org List-ID: Now, we capture a data corruption problem on ext4 while we're truncating an extent index block. Imaging that if we are revoking a buffer which has been journaled by the committing transaction, the buffer's jbddirty flag will not be cleared in jbd2_journal_forget(), so the commit code will set the buffer dirty flag again after refile the buffer. fsx kjournald2 jbd2_journal_commit_transaction jbd2_journal_revoke commit phase 1~5... jbd2_journal_forget belongs to older transaction commit phase 6 jbddirty not clear __jbd2_journal_refile_buffer __jbd2_journal_unfile_buffer test_clear_buffer_jbddirty mark_buffer_dirty Finally, if the freed extent index block was allocated again as data block by some other files, it may corrupt the file data when writing cached pages later, such as during umount time. This patch mark buffer as freed and set j_next_transaction to the new transaction when it already belongs to the committing transaction in jbd2_journal_forget(), so that commit code knows it should clear dirty bits when it is done with the buffer. This problem can be reproduced by xfstests generic/455 easily with seeds (3246 3247 3248 3249). Signed-off-by: zhangyi (F) Cc: stable@vger.kernel.org --- fs/jbd2/transaction.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index f07f006..f7f9647 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -1609,14 +1609,19 @@ int jbd2_journal_forget (handle_t *handle, struct buffer_head *bh) /* However, if the buffer is still owned by a prior * (committing) transaction, we can't drop it yet... */ JBUFFER_TRACE(jh, "belongs to older transaction"); - /* ... but we CAN drop it from the new transaction if we - * have also modified it since the original commit. */ + /* ... but we CAN drop it from the new transaction, mark + * buffer as freed and set j_next_transaction to the new + * transaction so that commit code knows it should clear + * dirty bits when it is done with the buffer. */ - if (jh->b_next_transaction) { - J_ASSERT(jh->b_next_transaction == transaction); + set_buffer_freed(bh); + + if (!jh->b_next_transaction) { spin_lock(&journal->j_list_lock); - jh->b_next_transaction = NULL; + jh->b_next_transaction = transaction; spin_unlock(&journal->j_list_lock); + } else { + J_ASSERT(jh->b_next_transaction == transaction); /* * only drop a reference if this transaction modified -- 2.7.4