Messages in this thread | | | Date | Mon, 23 Jan 2006 17:01:47 +0000 | From | Alasdair G Kergon <> | Subject | Re: [PATCH 6/9] device-mapper snapshot: barriers not supported |
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On Sun, Jan 22, 2006 at 09:41:11PM -0800, Andrew Morton wrote: > Alasdair G Kergon <agk@redhat.com> wrote: > > The snapshot and origin targets are incapable of handling barriers and > > need to indicate this.
> And what was happening if people _were_ sending such BIOs down? Did it all > appear to work correctly?
The snapshot target ignores the barrier and in some circumstances I/O can be reordered in ways that are meant to be prevented by the barrier.
> If so, will this change cause > currently-apparently-working setups to stop working?
As Lars pointed out, filesystems should already cope with -EOPNOTSUPP transparently, and it would be sensible for any out-of-tree users to do likewise.
Alasdair -- agk@redhat.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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