On Thu, Oct 28, 2010 at 08:57:49PM +0300, Pekka Enberg wrote: > Don't we need to call ext4_should_writeback_data() before we drop the > lock? It pokes at ->i_mode which needs ->i_mutex AFAICT. No, it should be fine. It's not like a file is going to change from being a regular file to a directory or vice versa. :-) >From a quick inspection it looks OK, but I haven't had the time to look more closely to be 100% sure, and of course I haven't run it through a battery of regression tests. For normal usage it should be fine though. Aidar, if you'd be willing to try it with this patch applied, and with the file system mounted data=writeback, and then let me know what the latencytop reports, that would be useful. I'm fairly sure that fixing llseek() probably won't make that much difference, since it will probably spread things out to other places, but it would be good to make the experiment. We will probably also need to use the uninitialized bit for protecting data from showing up after a crash for extent-based files, and turning on data=writeback is a good way to simulate that. (Sorry, no way we're going to make a change like that this merge cycle, but that might be something we could do for 2.6.38.) But I am curious to see what are the next things that come up as being problematic after that. Thanks, - Ted -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>