as-iosched deals with aliased requests differently from other ioscheds.
It links together aliased requests using rq->queuelist instead of
spilling alises to dispatch queue like other ioscheds do. Requests
linked in this way cannot be merged.
Unfortunately, generic q->last_merge handling patch didn't take this
into account and q->last_merge could be set to an aliased request
resulting in Badness, corrupt list and eventually panic.
This explicitly marks aliased requests to be unmergeable.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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