Messages in this thread | | | Date | Thu, 22 Jun 2006 14:21:44 +0100 | From | Alasdair G Kergon <> | Subject | Re: [PATCH 01/15] dm: support ioctls on mapped devices |
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On Wed, Jun 21, 2006 at 08:52:06PM -0700, Andrew Morton wrote: > I don't understand that. We're taking an ioctl against a dm device and > we're passing it through to an underlying device? Or something else?
Indeed. The motivation behind this came from multipath: people want to issue certain types of ioctls directly against a dm multipath device and have them pass through one of the paths to the underlying device. (Otherwise they'd need a knowledge of dm internals to poke around the tree of dm devices and probe path statuses to determine the correct path(s) to use - effectively implementing 'multipath' ioctls themselves from userspace with unavoidable races.)
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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