From patchwork Thu Mar 11 15:40:30 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: ext4: fix io-barrier logic for external journal case Date: Thu, 11 Mar 2010 05:40:30 -0000 From: Dmitri Monakho X-Patchwork-Id: 47343 Message-Id: <87wrxij28h.fsf@openvz.org> To: linux-ext4@vger.kernel.org Cc: Theodore Ts'o , Jan Kara We have to submit barrier before we start journal commit process. otherwise transaction may be committed before data flushed to disk. There is no difference from performance of view, but definitely fsync becomes more correct. If jbd2_log_start_commit return 0 then it means that transaction was already committed. So we don't have to issue barrier for ordered mode, because it was already done during commit. By unknown reason we ignored ret val from jbd2_log_wait_commit() so even in case of EIO fsync will succeed. Signed-off-by: Dmitry Monakhov --- fs/ext4/fsync.c | 28 +++++++++++++--------------- 1 files changed, 13 insertions(+), 15 deletions(-) diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c index 0d0c323..621a8ed 100644 --- a/fs/ext4/fsync.c +++ b/fs/ext4/fsync.c @@ -88,21 +88,19 @@ int ext4_sync_file(struct file *file, struct dentry *dentry, int datasync) return ext4_force_commit(inode->i_sb); commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid; - if (jbd2_log_start_commit(journal, commit_tid)) { - /* - * When the journal is on a different device than the - * fs data disk, we need to issue the barrier in - * writeback mode. (In ordered mode, the jbd2 layer - * will take care of issuing the barrier. In - * data=journal, all of the data blocks are written to - * the journal device.) - */ - if (ext4_should_writeback_data(inode) && - (journal->j_fs_dev != journal->j_dev) && - (journal->j_flags & JBD2_BARRIER)) - blkdev_issue_flush(inode->i_sb->s_bdev, NULL); - jbd2_log_wait_commit(journal, commit_tid); - } else if (journal->j_flags & JBD2_BARRIER) + /* + * When the journal is on a different device than the + * fs data disk, we need to issue the barrier in + * writeback mode. (In ordered mode, the jbd2 layer + * will take care of issuing the barrier. In + * data=journal, all of the data blocks are written to + * the journal device.) + */ + if (ext4_should_writeback_data(inode) && + (journal->j_fs_dev != journal->j_dev) && + (journal->j_flags & JBD2_BARRIER)) blkdev_issue_flush(inode->i_sb->s_bdev, NULL); + if (jbd2_log_start_commit(journal, commit_tid)) + ret = jbd2_log_wait_commit(journal, commit_tid); return ret; }