On Sat, Nov 23, 2013 at 12:41:06AM -0800, Christoph Hellwig wrote: > On Sat, Nov 23, 2013 at 09:40:38AM +1100, Dave Chinner wrote: > > > geometry, and we already have it wired to to large sector size > > > testing in xfstests. > > > > We don't need to screw around with the sector size - that is > > irrelevant to the problem, and we have an allocation alignment > > test that is supposed to catch these issues: generic/223. > > It didn't imply we need large sector sizes, but the same mechanism > to expodse a large sector size can also be used to present large > stripe units/width. > > > As I said, I have seen occasional failures of that test (once a > > month, on average) as a result of this bug. It was simply not often > > enough - running in a hard loop didn't increase the frequency of > > failures - to be able debug it or to reach my "there's a regression > > I need to look at" threshold. Perhaps we need to revisit that test > > and see if we can make it more likely to trigger failures... > > Seems like 233 should have cought it regularly with the explicit > alignment options on mkfs time. Maybe we also need a test mirroring > the plain dd more closely? Preallocation showed the problem, too, so we probably don't even need dd to check whether allocation alignment is working properly. We should probably write a test that spefically checks all the different anlignment/extent size combinations we can use. Preallocation should behave very similarly to direct IO, but I'm pretty sure that it won't do things like round up allocations to stripe unit/widths like direct IO does. The fact that we do allocation sunit/swidth size alignment for direct Io outside the allocator and sunit/swidth offset alignment inside the allocation is kinda funky.... > I've not seen 233 fail for a long time.. Not surprising, it is a one in several hundred test runs occurrence here... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
