Hey, > Taking a quick look at something I have laying around that you sent > previously (I assume the test hasn't changed much), I see we basically > create an overprovisioned dm-thin vol, mount it and dio write to it > until we start to see async write failures. So is the purpose of the > wait that we need the AIL to push and ultimately fail the associated > buffers before we attempt an unmount? If so, I'm wondering if you could > xfs_freeze the fs rather than wait (it looks like freeze sync pushes the > AIL)..? > As we discussed off-list, yes, I'd done some testing, and I believe we can use freezing to test it. > > > > > > > > I think we all agree that generic error injection (which Darrick has > > > > started playing with, but I haven't looked at yet) doesn't need to be > > > > bundled with this series (I hope we didn't scare you there ;). What I > > > > was asking for is a single patch that adds error injection in one spot > > > > with a configurable frequency. I'll refer to commit 609adfc2ed ("xfs: > > > > debug mode log record crc error injection") again because it is a simple > > > > example of a small DEBUG only hunk of code and boilerplate code to add a > > > > sysfs knob. > > > > > > > > I'll keep this in mind, and try to work on something like that :) > > > > I think error injection would make this test more straightforward > because you can explicitly control when I/Os fail and there's no need to > play around with dm-thin. That of course doesn't mean there isn't value > in having a test for fs' in dm-thin out of space conditions in general. > :) Well, this is doable, although it has a caveat. To do this, we'd need to inject the error in the buffer during IO completion, for example in xfs_buf_ioend(). The problem though, is that we start to have IOs before the 'mp->m_errotag' is actually initialized, so, xfs_buf_ioend() would need to check for m_errortag initialization before calling XFS_TEST_ERROR(). Something like this: bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD); + if (bp->b_target->bt_mount->m_errortag) { + if (XFS_TEST_ERROR(false, bp->b_target->bt_mount, + XFS_ERRTAG_BUF_WB)) { + bp->b_io_error = -ENOSPC; + } + } This check could also be done in xfs_errortag_test(), although I'm not sure if it's worth, giving that there are very few places where error injection can be useful and m_errortag can be uninitialized. Thoughts? -- Carlos -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html