> > 在 2017年12月11日，下午6:46，Amir Goldstein <amir73il@xxxxxxxxx> 写道： > > 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? Sorry，We have to finish test in 30 seconds after we write test file, otherwise may be affected by background flusher. > >> 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. As I know, in normal case flusher thread check dirty inode expiring every 5 seconds(default) and flush dirty inode when expires 30 seconds(default). If we can finish test in 30s after running test, it would be OK. What do you think? > > 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
