On Thu, Jan 07, 2016 at 12:47:36PM +0100, Jan Kara wrote: > > The problem is in all kernels starting with 3.8. Attached is a patch which > should fix the issue. Can you test whether it fixes the problem for you? Sorry, I missed this patch because it was attached to an discussion thread. > The problem is that although for delayed allocated blocks we write their > contents immediately after allocating them, there is no guarantee that > the IO scheduler or device doesn't reorder things I don't think that's the problem. In the commit thread when we call blkdev_issue_flush() that acts as a barrier so the I/O scheduler won't reorder writes after that point, which is before we write the commit block. Instead, I believe the problem is in ext4_writepages: ext4_journal_stop(handle); /* Submit prepared bio */ ext4_io_submit(&mpd.io_submit); Once we release the handle, the commit can start --- *before* we have a chance to submit the I/O. Oops. I believe if we swap these two calls, it should fix the problem Huang was seeing. Jan, do you agree? - 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
