On Sat, Dec 25, 2010 at 09:15:28PM +0800, Yongqiang Yang wrote: > > I found that if a block'allocation is delayed, and is not allocated > when journal flushes it, then journal just redirties it and return in > journal_submit_data_buffers. > > If I understand right, how to guarantee that the journal mode is ordered? The primary goal of ordered mode is to make sure that stale data is not exposed after a crash. To the extent that delayed allocation also achieves this goal, it's fine. The fact that ext3 forced data blocks out as part of its jbd commit function was always an implementation detail. In the long run we'll be getting rid of ordered mode even more so, by writing the data block first, and only then updating the file system metadata. At that point there will be no ordered flushing at all, and in fact ordered mode will go away as a journal mode supported by ext4. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
