On Mon, Dec 11, 2017 at 12:03 PM, Chengguang Xu <cgxu519@xxxxxxxxxx> wrote: >> >> 在 2017年12月7日，下午4:17，Amir Goldstein <amir73il@xxxxxxxxx> 写道： [...] > > I did more detail tests for three different data modes of ext4 and found > the overlayfs syncfs bug is reproducible on data=ordered and data=writeback, > but on data=journal mode, data is flushed and correct. That is expected, because overlayfs does call upper's sync_fs() method and for journal=data that will flush all dirty pages as well. > I only wrote only a few words > to a single file and the bug is always reproducible on my test environment. > > For writeback interferences, AFAIK, from dirty ratio and period. > If we drop all dirty caches & sync before the test, I think we can > avoid interference from it. > Why? does either drop_caches or sync() reset the flusher thread periodic flush dirty pages? > So if we don’t have anything else to interference test result, > I just want to modify to write a small single file as test target. > > Am I missing anything? I think the chance of flusher thread interfering the test and flushing the dirty page you wrote before _scratch_shutdown exists, but is small enough so we can neglect it and keep the test as simple as possible. Amir. -- To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
